What makes Duncan overrated

[KobeOwnsDuncan]

Here is the most overrated legend of our times, Mr Fundamentals; or should I say Mr Opportunity. Duncan is a solid all around player there is no denying that, but for anyone who remembers the NBA beyond 2000 you know that Duncan is not as good as everyone says he is. For starters he is a center who was converted to power forward because the Spurs had David Robinson. Duncan stand at about seven feet, the modern power forward today averages about six foot eight inches, which means Duncan has a good four inches on them.

The rules of today’s game have also helped Duncan a lot. In a game were defense is all but abolished, a player with little offensive skills can look really good because they can’t be touched. If Duncan played in the early 90s, he would be nothing more than a sixth man defensive plug.

[Halberto]

6DYJKoCjWrQ

you see a lot of centers do this?

LOL what a fail troll. So players like Duncan are benefiting from the game more today, and not players such as Kobe, Wade and Durant?


Fail.

[Dex]

:lobt::lobt::lobt::lobt:

[BlackSwordsMan]

He got to play with the best coach ever in NBA, the best bench player ever and top 10 PG of all time and only got 4 rings. He's highly over rated

[Tinystarz]

http://i53.tinypic.com/21ci689.gif

[spurs_fan_in_exile]

This is what passes for trolling these days? Damn kids with their baggy shorts and their snorting bath salts and their hip hopping music.

[Dunc n Dave]

lol this guy saying Duncan benefited from rule changes when he has a pic of KoMe in his sig. :lol

Last time I checked the "rule changes" helped the perimeter players out by not allowing hand checking. In the meantime, they let the post players get away with murder in the paint on a regular basis.

obvious troll is obvious:nope

[Tree of Woe]

how will spurfan recover from this sick burn?

[KobeOwnsDuncan]

lol this guy saying Duncan benefited from rule changes when he has a pic of KoMe in his sig. :lol

Last time I checked the "rule changes" helped the perimeter players out by not allowing hand checking. In the meantime, they let the post players get away with murder in the paint on a regular basis.

obvious troll is obvious:nope
:lol Phantom call champ

[ambchang]

TBH, if Duncan actually got his wish and played PG, he would have averaged 75 ppg, 22 apg, 28 rpg, 11 bpg and 8 spg on 74 FG% shooting because he would have a 9 inch advantage against his average competition.

[Leetonidas]

Quantum chromodynamics
From Wikipedia, the free encyclopedia
Standard model of particle physics
Feynmann Diagram Gluon Radiation.svg
Standard Model
[show]Background
[show]Constituents
[show]Limitations
[show]Theorists
v · d · e

In theoretical physics, quantum chromodynamics (QCD) is a theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons making up hadrons (such as the proton, neutron or pion). It is the study of the SU(3) Yang–Mills theory of color-charged fermions (the quarks). QCD is a quantum field theory of a special kind called a non-abelian gauge theory. It is an important part of the Standard Model of particle physics. A huge body of experimental evidence for QCD has been gathered over the years.

QCD enjoys two peculiar properties:

Confinement, which means that the force between quarks does not diminish as they are separated. Because of this, it would take an infinite amount of energy to separate two quarks; they are forever bound into hadrons such as the proton and the neutron. Although analytically unproven, confinement is widely believed to be true because it explains the consistent failure of free quark searches, and it is easy to demonstrate in lattice QCD.
Asymptotic freedom, which means that in very high-energy reactions, quarks and gluons interact very weakly. This prediction of QCD was first discovered in the early 1970s by David Politzer and by Frank Wilczek and David Gross. For this work they were awarded the 2004 Nobel Prize in Physics.

There is no known phase-transition line separating these two properties; confinement is dominant in low-energy scales but, as energy increases, asymptotic freedom becomes dominant.
Contents
[hide]

1 Terminology
2 History
3 Theory
3.1 Some definitions
3.2 Additional remarks: duality
3.3 Symmetry groups
3.4 Lagrangian
3.5 Fields
3.6 Dynamics
3.7 Area law and confinement
4 Methods
4.1 Perturbative QCD
4.2 Lattice QCD
4.3 1/N expansion
4.4 Effective theories
4.5 QCD Sum Rules
4.6 Nambu-Jona-Lasinio model
5 Experimental tests
6 Cross-relations to Solid State Physics
7 See also
8 References
9 Further reading
10 External links

[edit] Terminology

The word quark was coined by American physicist Murray Gell-Mann (b. 1929) in its present sense. It originally comes from the phrase "Three quarks for Muster Mark" in Finnegans Wake by James Joyce. On June 27, 1978, Gell-Mann wrote a private letter to the editor of the Oxford English Dictionary, in which he related that he had been influenced by Joyce's words: "The allusion to three quarks seemed perfect." (Originally, only three quarks had been discovered.) Gell-Mann, however, wanted to pronounce the word with (ô) not (ä), as Joyce seemed to indicate by rhyming words in the vicinity such as Mark. Gell-Mann got around that "by supposing that one ingredient of the line 'Three quarks for Muster Mark' was a cry of 'Three quarts for Mister . . . ' heard in H.C. Earwicker's pub," a plausible suggestion given the complex punning in Joyce's novel.[1]

The three kinds of charge in QCD (as opposed to one in quantum electrodynamics or QED) are usually referred to as "color charge" by loose analogy to the three kinds of color (red, green and blue) perceived by humans. Other than this nomenclature, the quantum parameter "color" is completely unrelated to the everyday, familiar phenomenon of color.

Since the theory of electric charge is dubbed "electrodynamics", the Greek word "chroma" Χρώμα (meaning color) is applied to the theory of color charge, "chromodynamics".
[edit] History

With the invention of bubble chambers and spark chambers in the 1950s, experimental particle physics discovered a large and ever-growing number of particles called hadrons. It seemed that such a large number of particles could not all be fundamental. First, the particles were classified by charge and isospin by Eugene Wigner and Werner Heisenberg; then, in 1953, according to strangeness by Murray Gell-Mann and Kazuhiko Nishijima. To gain greater insight, the hadrons were sorted into groups having similar properties and masses using the eightfold way, invented in 1961 by Gell-Mann and Yuval Ne'eman. Gell-Mann and George Zweig, correcting an earlier approach of Shoichi Sakata, went on to propose in 1963 that the structure of the groups could be explained by the existence of three flavours of smaller particles inside the hadrons: the quarks.

Perhaps the first remark that quarks should possess an additional quantum number was made[2] as a short footnote in the preprint of Boris Struminsky[3] in connection with Ω − hyperon composed of three strange quarks with parallel spins (this situation was peculiar, because since quarks are fermions, such combination is forbidden by the Pauli exclusion principle):

Three identical quarks cannot form an antisymmetric S-state. In order to realize an antisymmetric orbital S-state, it is necessary for the quark to have an additional quantum number.

— B. V. Struminsky, Magnetic moments of barions in the quark model, JINR-Preprint P-1939, Dubna, Submitted on January 7, 1965

Boris Struminsky was a PhD student of Nikolay Bogolyubov. The problem considered in this preprint was suggested by Nikolay Bogolyubov, who advised Boris Struminsky in this research.[3] In the beginning of 1965, Nikolay Bogolyubov, Boris Struminsky and Albert Tavchelidze wrote a preprint with a more detailed discussion of the additional quark quantum degree of freedom.[4] This work was also presented by Albert Tavchelidze without obtaining consent of his collaborators for doing so at an international conference in Trieste (Italy), in May 1965.[5][6]

A similar mysterious situation was with the Δ++ baryon; in the quark model, it is composed of three up quarks with parallel spins. In 1965, Moo-Young Han with Yoichiro Nambu and Oscar W. Greenberg independently resolved the problem by proposing that quarks possess an additional SU(3) gauge degree of freedom, later called color charge. Han and Nambu noted that quarks might interact via an octet of vector gauge bosons: the gluons.

Since free quark searches consistently failed to turn up any evidence for the new particles, and because an elementary particle back then was defined as a particle which could be separated and isolated, Gell-Mann often said that quarks were merely convenient mathematical constructs, not real particles. The meaning of this statement was usually clear in context: He meant quarks are confined, but he also was implying that the strong interactions could probably not be fully described by quantum field theory.

Richard Feynman argued that high energy experiments showed quarks are real particles: he called them partons (since they were parts of hadrons). By particles, Feynman meant objects which travel along paths, elementary particles in a field theory.

The difference between Feynman's and Gell-Mann's approaches reflected a deep split in the theoretical physics community. Feynman thought the quarks have a distribution of position or momentum, like any other particle, and he (correctly) believed that the diffusion of parton momentum explained diffractive scattering. Although Gell-Mann believed that certain quark charges could be localized, he was open to the possibility that the quarks themselves could not be localized because space and time break down. This was the more radical approach of S-matrix theory.

James Bjorken proposed that pointlike partons would imply certain relations should hold in deep inelastic scattering of electrons and protons, which were spectacularly verified in experiments at SLAC in 1969. This led physicists to abandon the S-matrix approach for the strong interactions.

The discovery of asymptotic freedom in the strong interactions by David Gross, David Politzer and Frank Wilczek allowed physicists to make precise predictions of the results of many high energy experiments using the quantum field theory technique of perturbation theory. Evidence of gluons was discovered in three jet events at PETRA in 1979. These experiments became more and more precise, culminating in the verification of perturbative QCD at the level of a few percent at the LEP in CERN.

The other side of asymptotic freedom is confinement. Since the force between color charges does not decrease with distance, it is believed that quarks and gluons can never be liberated from hadrons. This aspect of the theory is verified within lattice QCD computations, but is not mathematically proven. One of the Millennium Prize Problems announced by the Clay Mathematics Institute requires a claimant to produce such a proof. Other aspects of non-perturbative QCD are the exploration of phases of quark matter, including the quark-gluon plasma.

The relation between the short-distance particle limit and the confining long-distance limit is one of the topics recently explored using string theory, the modern form of S-matrix theory.[7][8]
[edit] Theory
Unsolved problems in physics QCD in the non-perturbative regime:

Confinement: the equations of QCD remain unsolved at energy scales relevant for describing atomic nuclei. How does QCD give rise to the physics of nuclei and nuclear constituents?
Quark matter: the equations of QCD predict that a sea of quarks and gluons should be formed at high temperature and density. What are the properties of this phase of matter?

Question mark2.svg
[edit] Some definitions

Every field theory of particle physics is based on certain symmetries of nature whose existence is deduced from observations. These can be

local symmetries, that is the symmetry acts independently at each point in space-time. Each such symmetry is the basis of a gauge theory and requires the introduction of its own gauge bosons.
global symmetries, which are symmetries whose operations must be simultaneously applied to all points of space-time.

QCD is a gauge theory of the SU(3) gauge group obtained by taking the color charge to define a local symmetry.

Since the strong interaction does not discriminate between different flavors of quark, QCD has approximate flavor symmetry, which is broken by the differing masses of the quarks.

There are additional global symmetries whose definitions require the notion of chirality, discrimination between left and right-handed. If the spin of a particle has a positive projection on its direction of motion then it is called left-handed; otherwise, it is right-handed. Chirality and handedness are not the same, but become approximately equivalent at high energies.

Chiral symmetries involve independent transformations of these two types of particle.
Vector symmetries (also called diagonal symmetries) mean the same transformation is applied on the two chiralities.
Axial symmetries are those in which one transformation is applied on left-handed particles and the inverse on the right-handed particles.

[edit] Additional remarks: duality

As mentioned, asymptotic freedom means that at large energy - this corresponds also to short distances - there is practically no interaction between the particles. This is in contrast - more precisely one would say dual - to what one is used to, since usually one connects the absence of interactions with large distances. However, as already mentioned in the original paper of Franz Wegner,[9] a solid state theorist who introduced 1971 simple gauge invariant lattice models, the high-temperature behaviour of the original model, e.g. the strong decay of correlations at large distances, corresponds to the low-temperature behaviour of the (usually ordered!) dual model, namely the asymptotic decay of non-trivial correlations, e.g. short-range deviations from almost perfect arrangements, for short distances. Here, in contrast to Wegner, we have only the dual model, which is that one described in this article.[10]
[edit] Symmetry groups

The color group SU(3) corresponds to the local symmetry whose gauging gives rise to QCD. The electric charge labels a representation of the local symmetry group U(1) which is gauged to give QED: this is an abelian group. If one considers a version of QCD with Nf flavors of massless quarks, then there is a global (chiral) flavor symmetry group SU_L(N_f)\times SU_R(N_f)\times U_B(1)\times U_A(1). The chiral symmetry is spontaneously broken by the QCD vacuum to the vector (L+R) SUV(Nf) with the formation of a chiral condensate. The vector symmetry, UB(1) corresponds to the baryon number of quarks and is an exact symmetry. The axial symmetry UA(1) is exact in the classical theory, but broken in the quantum theory, an occurrence called an anomaly. Gluon field configurations called instantons are closely related to this anomaly.

There are two different types of SU(3) symmetry: there is the symmetry that acts on the different colors of quarks, and this is an exact gauge symmetry mediated by the gluons, and there is also a flavor symmetry which rotates different flavors of quarks to each other, or flavor SU(3). Flavor SU(3) is an approximate symmetry of the vacuum of QCD, and is not a fundamental symmetry at all. It is an accidental consequence of the small mass of the three lightest quarks.

In the QCD vacuum there are vacuum condensates of all the quarks whose mass is less than the QCD scale. This includes the up and down quarks, and to a lesser extent the strange quark, but not any of the others. The vacuum is symmetric under SU(2) isospin rotations of up and down, and to a lesser extent under rotations of up, down and strange, or full flavor group SU(3), and the observed particles make isospin and SU(3) multiplets.

The approximate flavor symmetries do have associated gauge bosons, observed particles like the rho and the omega, but these particles are nothing like the gluons and they are not massless. They are emergent gauge bosons in an approximate string description of QCD.
[edit] Lagrangian

The dynamics of the quarks and gluons are controlled by the quantum chromodynamics Lagrangian. The gauge invariant QCD Lagrangian is

\begin{align} \mathcal{L}_\mathrm{QCD} & = \bar{\psi}_i\left(i \gamma^\mu (D_\mu)_{ij} - m\, \delta_{ij}\right) \psi_j - \frac{1}{4}G^a_{\mu \nu} G^{\mu \nu}_a \\ & = \bar{\psi}_i (i \gamma^\mu \partial_\mu - m )\psi_i - g G^a_\mu \bar{\psi}_i \gamma^\mu T^a_{ij} \psi_j - \frac{1}{4}G^a_{\mu \nu} G^{\mu \nu}_a \,,\\ \end{align}

where \psi_i(x) \, is the quark field, a dynamical function of space-time, in the fundamental representation of the SU(3) gauge group, indexed by i,\,j,\,\ldots; G^a_\mu(x) \, are the gluon fields, also a dynamical function of space-time, in the adjoint representation of the SU(3) gauge group, indexed by a,\,b,\,\ldots . The \gamma^\mu \, are Dirac matrices connecting the spinor representation to the vector representation of the Lorentz group; and T^a_{ij} \, are the generators connecting the fundamental, antifundamental and adjoint representations of the SU(3) gauge group. The Gell-Mann matrices provide one such representation for the generators.

The symbol G^a_{\mu \nu} \, represents the gauge invariant gluonic field strength tensor, analogous to the electromagnetic field strength tensor, F^{\mu \nu} \,, in Electrodynamics. It is given by

G^a_{\mu \nu} = \partial_\mu G^a_{\nu} - \partial_\nu G^a_\mu - g f^{abc} G^b_\mu G^c_\nu \,,

where f_{abc} \, are the structure constants of SU(3). Note that the rules to move-up or pull-down the a, b, or c indexes are trivial, (+......+), so that f^{abc}=f_{abc}=f^a_{bc}\,, whereas for the μ or ν indexes one has the non-trivial relativistic rules, corresponding e.g. to the signature (+---). Furthermore, for mathematicians, according to this formula the gluon colour field can be represented by a SU(3)-Lie algebra-valued "curvature"-2-form \mathbf G=\mathrm d\mathbf {\tilde G}-g\,\mathbf {\tilde G}\wedge \mathbf {\tilde G}\,, where \mathbf {\tilde G} is a "vector potential"-1-form corresponding to \mathbf G and \wedge is the (antisymmetric) "wedge product" of this algebra, producing the "structure constants" fabc. The Cartan-derivative of the field form (i.e. essentially the divergence of the field) would be zero in the absence of the "gluon terms", i.e. those ~ g, which represent the non-abelian character of the SU(3).

The constants m and g control the quark mass and coupling constants of the theory, subject to renormalization in the full quantum theory.

An important theoretical notion concerning the final term of the above Lagrangian is the Wilson loop variable. This loop variable plays a most-important role in discretized forms of the QCD (see lattice QCD), and more generally, it distinguishes confined and deconfined states of a gauge theory. It was introduced by the Nobel prize winner Kenneth G. Wilson and is treated in a separate article.
[edit] Fields

Quarks are massive spin-1/2 fermions which carry a color charge whose gauging is the content of QCD. Quarks are represented by Dirac fields in the fundamental representation 3 of the gauge group SU(3). They also carry electric charge (either -1/3 or 2/3) and participate in weak interactions as part of weak isospin doublets. They carry global quantum numbers including the baryon number, which is 1/3 for each quark, hypercharge and one of the flavor quantum numbers.

Gluons are spin-1 bosons which also carry color charges, since they lie in the adjoint representation 8 of SU(3). They have no electric charge, do not participate in the weak interactions, and have no flavor. They lie in the singlet representation 1 of all these symmetry groups.

Every quark has its own antiquark. The charge of each antiquark is exactly the opposite of the corresponding quark.
[edit] Dynamics

According to the rules of quantum field theory, and the associated Feynman diagrams, the above theory gives rise to three basic interactions: a quark may emit (or absorb) a gluon, a gluon may emit (or absorb) a gluon, and two gluons may directly interact. This contrasts with QED, in which only the first kind of interaction occurs, since photons have no charge. Diagrams involving Faddeev–Popov ghosts must be considered too.
[edit] Area law and confinement

Detailed computations with the above-mentioned Lagrangian[11] show that the effective potential between a quark and its anti-quark in a meson contains a term \propto r, which represents some kind of "stiffness" of the interaction between the particle and its anti-particle at large distances, similar to the entropic elasticity of a rubber band (see below). This leads to confinement [12] of the quarks to the interior of hadrons, i.e. mesons and nucleons, with typical radii Rc, corresponding to former "Bag models" of the hadrons[13] . The order of magnitude of the "bag radius" is 1 fm (=10−15 m). Moreover, the above-mentioned stiffness is quantitatively related to the so-called "area law" behaviour of the expectation value of the Wilson loop product \,P_W of the ordered coupling constants around a closed loop W; i.e. \,\langle P_W\rangle is proportional to the area enclosed by the loop. For this behaviour the non-abelian behaviour of the gauge group is essential.
[edit] Methods

Further analysis of the content of the theory is complicated. Various techniques have been developed to work with QCD. Some of them are discussed briefly below.
[edit] Perturbative QCD

This approach is based on asymptotic freedom, which allows perturbation theory to be used accurately in experiments performed at very high energies. Although limited in scope, this approach has resulted in the most precise tests of QCD to date.
[edit] Lattice QCD
Main article: Lattice QCD

Among non-perturbative approaches to QCD, the most well established one is lattice QCD. This approach uses a discrete set of space-time points (called the lattice) to reduce the analytically intractable path integrals of the continuum theory to a very difficult numerical computation which is then carried out on supercomputers like the QCDOC which was constructed for precisely this purpose. While it is a slow and resource-intensive approach, it has wide applicability, giving insight into parts of the theory inaccessible by other means. However, the numerical sign problem makes it difficult to use lattice methods to study QCD at high density and low temperature (e.g. nuclear matter or the interior of neutron stars).
[edit] 1/N expansion
Main article: 1/N expansion

A well-known approximation scheme, the 1/N expansion, starts from the premise that the number of colors is infinite, and makes a series of corrections to account for the fact that it is not. Until now it has been the source of qualitative insight rather than a method for quantitative predictions. Modern variants include the AdS/CFT approach.
[edit] Effective theories

For specific problems effective theories may be written down which give qualitatively correct results in certain limits. In the best of cases, these may then be obtained as systematic expansions in some parameter of the QCD Lagrangian. One such effective field theory is chiral perturbation theory or ChiPT, which is the QCD effective theory at low energies. More precisely, it is a low energy expansion based on the spontaneous chiral symmetry breaking of QCD, which is an exact symmetry when quark masses are equal to zero, but for the u,d and s quark, which have small mass, it is still a good approximate symmetry. Depending on the number of quarks which are treated as light, one uses either SU(2) ChiPT or SU(3) ChiPT . Other effective theories are heavy quark effective theory (which expands around heavy quark mass near infinity), and soft-collinear effective theory (which expands around large ratios of energy scales). In addition to effective theories, models like the Nambu-Jona-Lasinio model and the chiral model are often used when discussing general features.
[edit] QCD Sum Rules
Main article: QCD sum rules

Based on an Operator product expansion one can derive sets of relations that connect different observables with each other.
[edit] Nambu-Jona-Lasinio model

A recent work by Kei-Ichi Kondo shows that the proper low-energy limit for QCD is a Nambu-Jona-Lasinio model extended to a Polyakov-Nambu-Jona-Lasinio model at finite temperature[14].
[edit] Experimental tests

The notion of quark flavours was prompted by the necessity of explaining the properties of hadrons during the development of the quark model. The notion of colour was necessitated by the puzzle of the Δ++
. This has been dealt with in the section on the history of QCD.

The first evidence for quarks as real constituent elements of hadrons was obtained in deep inelastic scattering experiments at SLAC. The first evidence for gluons came in three jet events at PETRA.

Good quantitative tests of perturbative QCD are

the running of the QCD coupling as deduced from many observations
scaling violation in polarized and unpolarized deep inelastic scattering
vector boson production at colliders (this includes the Drell-Yan process)
jet cross sections in colliders
event shape observables at the LEP
heavy-quark production in colliders

Quantitative tests of non-perturbative QCD are fewer, because the predictions are harder to make. The best is probably the running of the QCD coupling as probed through lattice computations of heavy-quarkonium spectra. There is a recent claim about the mass of the heavy meson Bc [4]. Other non-perturbative tests are currently at the level of 5% at best. Continuing work on masses and form factors of hadrons and their weak matrix elements are promising candidates for future quantitative tests. The whole subject of quark matter and the quark-gluon plasma is a non-perturbative test bed for QCD which still remains to be properly exploited.
[edit] Cross-relations to Solid State Physics

There are unexpected cross-relations to solid state physics. For example, the notion of gauge invariance forms the basis of the well-known Mattis spin glasses,[15] which are systems with the usual spin degrees of freedom s_i=\pm 1\, for i =1,...,N, with the special fixed "random" couplings J_{i,k}=\epsilon_i \,J_0\,\epsilon_k\,. Here the εi and εk quantities can independently and "randomly" take the values \pm 1, which corresponds to a most-simple gauge transformation (\,s_i\to s_i\cdot\epsilon_i\quad\,J_{i,k}\to \epsilon_i J_{i,k}\epsilon_k\,\quad s_k\to s_k\cdot\epsilon_k \,)\,. This means that thermodynamic expectation values of measurable quantities, e.g. of the energy {\mathcal H}:=-\sum s_i\,J_{i,k}\,s_k\,, are invariant.

However, here the coupling degrees of freedom Ji,k, which in the QCD correspond to the gluons, are "frozen" to fixed values (quenching). In contrast, in the QCD they "fluctuate" (annealing), and through the large number of gauge degrees of freedom the entropy plays an important role (see below).

For positive J0 the thermodynamics of the Mattis spin glass corresponds in fact simply to a ferromagnet, just because these systems have no "frustration“ at all. This term is a basic measure in spin glass theory.[16] Quantitatively it is identical with the loop-product P_W:\,=\,J_{i,k}J_{k,l}...J_{n,m}J_{m,i} along a closed loop W. However, for a Mattis spin glass - in contrast to "genuine" spin glasses - the quantity PW never becomes negative.

The basic notion "frustration" of the spin-glass is actually similar to the Wilson loop quantity of the QCD. The only difference is again that in the QCD one is dealing with SU(3) matrices, and that one is dealing with a "fluctuating" quantity. Energetically, perfect absence of frustration should be non-favorable and atypical for a spin glass, which means that one should add the loop-product to the Hamiltonian, by some kind of term representing a "punishment". - In the QCD the Wilson loop is essential for the Lagrangian rightaway.

The relation between the QCD and "disordered magnetic systems" (the spin glasses belong to them) were additionally stressed in a paper by Fradkin, Huberman und Shenker,[17] which also stresses the notion of duality.

A further analogy consists in the already mentioned similarity to polymer physics, where, analogously to Wilson Loops, so-called "entangled nets" appear, which are important for the formation of the entropy-elasticity (force proportional to the length) of a rubber band. The non-abelian character of the SU(3) corresponds thereby to the non-trivial "chemical links“, which glue different loop segments together, and "asymptotic freedom" means in the polymer analogy simply the fact that in the short-wave limit, i.e. for 0\leftarrow\lambda_w\ll R_c (where Rc is a characteristic correlation-length for the glued loops, corresponding to the above-mentioned "bag radius", while λw is the wavelength of an excitation) any non-trivial correlation vanishes totally, as if the system had crystallized.[18]

There is also a correspondence between confinement in QCD - the fact that the colour-field is only different from zero in the interior of hadrons - and the behaviour of the usual magnetic field in the theory of type-II superconductors: there the magnetism is confined to the interiour of the Abrikosov flux-line lattice,[19] i.e., the London penetration depth λ of that theory is analogous to the confinement radius Rc of quantum chromodynamics. Mathematically, this correspondendence is supported by the second term, \propto g G^a_\mu \bar{\psi}_i \gamma^\mu T^a_{ij} \psi_j\,, on the r.h.s. of the Lagrangian.
[edit] See also

For overviews, see Standard Model, its field theoretical formulation, strong interactions, quarks and gluons, hadrons, confinement, QCD matter, or quark-gluon plasma.
For details, see gauge theory, quantization procedure including BRST quantization and Faddeev–Popov ghosts. A more general category is quantum field theory.
For techniques, see Lattice QCD, 1/N expansion, perturbative QCD, Soft-collinear effective theory, heavy quark effective theory, chiral models, and the Nambu and Jona-Lasinio model.
For experiments, see quark search experiments, deep inelastic scattering, jet physics, quark-gluon plasma.

[edit] References

^ Gell-Mann, Murray (1995). The Quark and the Jaguar. Owl Books. ISBN 978-0805072532.
^ Fyodor Tkachov (2009). "A contribution to the history of quarks: Boris Struminsky's 1965 JINR publication". arXiv:0904.0343 [physics.hist-ph].
^ a b B. V. Struminsky, Magnetic moments of barions in the quark model. JINR-Preprint P-1939, Dubna, Russia. Submitted on January 7, 1965.
^ N. Bogolubov, B. Struminsky, A. Tavkhelidze. On composite models in the theory of elementary particles. JINR Preprint D-1968, Dubna 1965.
^ A. Tavkhelidze. Proc. Seminar on High Energy Physics and Elementary Particles, Trieste, 1965, Vienna IAEA, 1965, p. 763.
^ V. A. Matveev and A. N. Tavkhelidze (INR, RAS, Moscow) The quantum number color, colored quarks and QCD (Dedicated to the 40th Anniversary of the Discovery of the Quantum Number Color). Report presented at the 99th Session of the JINR Scientific Council, Dubna, 19–20 January 2006.
^ J. Polchinski, M. Strassler (2002). "Hard Scattering and Gauge/String duality". Physical Review Letters 88 (3): 31601. arXiv:hep-th/0109174. Bibcode 2002PhRvL..88c1601P. doi:10.1103/PhysRevLett.88.031601. PMID 11801052.
^ Brower, Richard C.; Mathur, Samir D.; Chung-I Tan (2000). "Glueball Spectrum for QCD from AdS Supergravity Duality". arXiv:hep-th/0003115 [hep-th].
^ F. Wegner, Duality in Generalized Ising Models and Phase Transitions without Local Order Parameter, J. Math. Phys. 12 (1971) 2259-2272.

Reprinted in Claudio Rebbi (ed.), Lattice Gauge Theories and Monte Carlo Simulations, World Scientific, Singapore (1983), p. 60-73. Abstract: [1]

^ Perhaps one can guess that in the "original" model mainly the quarks would fluctuate, whereas in the present one, the "dual" model, mainly the gluons do.
^ See all standard textbooks on the QCD, e.g., those noted above
^ Only at extremely large pressures and or temperatures, e.g. for T\cong 5\cdot 10^{12} K or larger, confinement gives way to a quark-gluon plasma.
^ Kenneth A. Johnson, The bag model of quark confinement, Scientific American, July 1979
^ Kei-Ichi Kondo (2010). "Toward a first-principle derivation of confinement and chiral-symmetry-breaking crossover transitions in QCD". Physical Review D 82: 065024. arXiv:1005.0314v2. doi:10.1103/PhysRevD.82.065024.
^ D.C. Mattis, Phys. Lett. 56a (1976) 421
^ J. Vanninemus and G. Toulouse, J. Phys. C 10 (1977) 537
^ E. Fradkin, B.A. Huberman, S. Shenker, Gauge Symmetries in random magnetic systems, Phys. Rev. B 18 (1978) 4783-4794, [2]
^ A. Bergmann, A. Owen , Dielectric relaxation spectroscopy of poly[(R)-3-Hydroxybutyrate] (PHD) during crystallization, Polymer International 53 (7) (2004) 863-868, [3]
^ Mathematically, the flux-line lattices are described by Emil Artin's braid group, which is nonabelian, since one braid can wind around another one.

[edit] Further reading

Greiner, Walter;Schäfer, Andreas (1994). Quantum Chromodynamics. Springer. ISBN 0-387-57103-5.
Halzen, Francis; Martin, Alan (1984). Quarks & Leptons: An Introductory Course in Modern Particle Physics. John Wiley & Sons. ISBN 0-471-88741-2.
Creutz, Michael (1985). Quarks, Gluons and Lattices. Cambridge University Press. ISBN 978-0521315357.

[edit] External links

Particle data group
The millennium prize for proving confinement
Ab Initio Determination of Light Hadron Masses
Andreas S Kronfeld The Weight of the World Is Quantum Chromodynamics
Andreas S Kronfeld Quantum chromodynamics with advanced computing
Standard model gets right answer
Quantum Chromodynamics

[Leetonidas]

Quantum chromodynamics
From Wikipedia, the free encyclopedia
Standard model of particle physics
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Standard Model
[show]Background
[show]Constituents
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In theoretical physics, quantum chromodynamics (QCD) is a theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons making up hadrons (such as the proton, neutron or pion). It is the study of the SU(3) Yang–Mills theory of color-charged fermions (the quarks). QCD is a quantum field theory of a special kind called a non-abelian gauge theory. It is an important part of the Standard Model of particle physics. A huge body of experimental evidence for QCD has been gathered over the years.

QCD enjoys two peculiar properties:

Confinement, which means that the force between quarks does not diminish as they are separated. Because of this, it would take an infinite amount of energy to separate two quarks; they are forever bound into hadrons such as the proton and the neutron. Although analytically unproven, confinement is widely believed to be true because it explains the consistent failure of free quark searches, and it is easy to demonstrate in lattice QCD.
Asymptotic freedom, which means that in very high-energy reactions, quarks and gluons interact very weakly. This prediction of QCD was first discovered in the early 1970s by David Politzer and by Frank Wilczek and David Gross. For this work they were awarded the 2004 Nobel Prize in Physics.

There is no known phase-transition line separating these two properties; confinement is dominant in low-energy scales but, as energy increases, asymptotic freedom becomes dominant.
Contents
[hide]

1 Terminology
2 History
3 Theory
3.1 Some definitions
3.2 Additional remarks: duality
3.3 Symmetry groups
3.4 Lagrangian
3.5 Fields
3.6 Dynamics
3.7 Area law and confinement
4 Methods
4.1 Perturbative QCD
4.2 Lattice QCD
4.3 1/N expansion
4.4 Effective theories
4.5 QCD Sum Rules
4.6 Nambu-Jona-Lasinio model
5 Experimental tests
6 Cross-relations to Solid State Physics
7 See also
8 References
9 Further reading
10 External links

[edit] Terminology

The word quark was coined by American physicist Murray Gell-Mann (b. 1929) in its present sense. It originally comes from the phrase "Three quarks for Muster Mark" in Finnegans Wake by James Joyce. On June 27, 1978, Gell-Mann wrote a private letter to the editor of the Oxford English Dictionary, in which he related that he had been influenced by Joyce's words: "The allusion to three quarks seemed perfect." (Originally, only three quarks had been discovered.) Gell-Mann, however, wanted to pronounce the word with (ô) not (ä), as Joyce seemed to indicate by rhyming words in the vicinity such as Mark. Gell-Mann got around that "by supposing that one ingredient of the line 'Three quarks for Muster Mark' was a cry of 'Three quarts for Mister . . . ' heard in H.C. Earwicker's pub," a plausible suggestion given the complex punning in Joyce's novel.[1]

The three kinds of charge in QCD (as opposed to one in quantum electrodynamics or QED) are usually referred to as "color charge" by loose analogy to the three kinds of color (red, green and blue) perceived by humans. Other than this nomenclature, the quantum parameter "color" is completely unrelated to the everyday, familiar phenomenon of color.

Since the theory of electric charge is dubbed "electrodynamics", the Greek word "chroma" Χρώμα (meaning color) is applied to the theory of color charge, "chromodynamics".
[edit] History

With the invention of bubble chambers and spark chambers in the 1950s, experimental particle physics discovered a large and ever-growing number of particles called hadrons. It seemed that such a large number of particles could not all be fundamental. First, the particles were classified by charge and isospin by Eugene Wigner and Werner Heisenberg; then, in 1953, according to strangeness by Murray Gell-Mann and Kazuhiko Nishijima. To gain greater insight, the hadrons were sorted into groups having similar properties and masses using the eightfold way, invented in 1961 by Gell-Mann and Yuval Ne'eman. Gell-Mann and George Zweig, correcting an earlier approach of Shoichi Sakata, went on to propose in 1963 that the structure of the groups could be explained by the existence of three flavours of smaller particles inside the hadrons: the quarks.

Perhaps the first remark that quarks should possess an additional quantum number was made[2] as a short footnote in the preprint of Boris Struminsky[3] in connection with Ω − hyperon composed of three strange quarks with parallel spins (this situation was peculiar, because since quarks are fermions, such combination is forbidden by the Pauli exclusion principle):

Three identical quarks cannot form an antisymmetric S-state. In order to realize an antisymmetric orbital S-state, it is necessary for the quark to have an additional quantum number.

— B. V. Struminsky, Magnetic moments of barions in the quark model, JINR-Preprint P-1939, Dubna, Submitted on January 7, 1965

Boris Struminsky was a PhD student of Nikolay Bogolyubov. The problem considered in this preprint was suggested by Nikolay Bogolyubov, who advised Boris Struminsky in this research.[3] In the beginning of 1965, Nikolay Bogolyubov, Boris Struminsky and Albert Tavchelidze wrote a preprint with a more detailed discussion of the additional quark quantum degree of freedom.[4] This work was also presented by Albert Tavchelidze without obtaining consent of his collaborators for doing so at an international conference in Trieste (Italy), in May 1965.[5][6]

A similar mysterious situation was with the Δ++ baryon; in the quark model, it is composed of three up quarks with parallel spins. In 1965, Moo-Young Han with Yoichiro Nambu and Oscar W. Greenberg independently resolved the problem by proposing that quarks possess an additional SU(3) gauge degree of freedom, later called color charge. Han and Nambu noted that quarks might interact via an octet of vector gauge bosons: the gluons.

Since free quark searches consistently failed to turn up any evidence for the new particles, and because an elementary particle back then was defined as a particle which could be separated and isolated, Gell-Mann often said that quarks were merely convenient mathematical constructs, not real particles. The meaning of this statement was usually clear in context: He meant quarks are confined, but he also was implying that the strong interactions could probably not be fully described by quantum field theory.

Richard Feynman argued that high energy experiments showed quarks are real particles: he called them partons (since they were parts of hadrons). By particles, Feynman meant objects which travel along paths, elementary particles in a field theory.

The difference between Feynman's and Gell-Mann's approaches reflected a deep split in the theoretical physics community. Feynman thought the quarks have a distribution of position or momentum, like any other particle, and he (correctly) believed that the diffusion of parton momentum explained diffractive scattering. Although Gell-Mann believed that certain quark charges could be localized, he was open to the possibility that the quarks themselves could not be localized because space and time break down. This was the more radical approach of S-matrix theory.

James Bjorken proposed that pointlike partons would imply certain relations should hold in deep inelastic scattering of electrons and protons, which were spectacularly verified in experiments at SLAC in 1969. This led physicists to abandon the S-matrix approach for the strong interactions.

The discovery of asymptotic freedom in the strong interactions by David Gross, David Politzer and Frank Wilczek allowed physicists to make precise predictions of the results of many high energy experiments using the quantum field theory technique of perturbation theory. Evidence of gluons was discovered in three jet events at PETRA in 1979. These experiments became more and more precise, culminating in the verification of perturbative QCD at the level of a few percent at the LEP in CERN.

The other side of asymptotic freedom is confinement. Since the force between color charges does not decrease with distance, it is believed that quarks and gluons can never be liberated from hadrons. This aspect of the theory is verified within lattice QCD computations, but is not mathematically proven. One of the Millennium Prize Problems announced by the Clay Mathematics Institute requires a claimant to produce such a proof. Other aspects of non-perturbative QCD are the exploration of phases of quark matter, including the quark-gluon plasma.

The relation between the short-distance particle limit and the confining long-distance limit is one of the topics recently explored using string theory, the modern form of S-matrix theory.[7][8]
[edit] Theory
Unsolved problems in physics QCD in the non-perturbative regime:

Confinement: the equations of QCD remain unsolved at energy scales relevant for describing atomic nuclei. How does QCD give rise to the physics of nuclei and nuclear constituents?
Quark matter: the equations of QCD predict that a sea of quarks and gluons should be formed at high temperature and density. What are the properties of this phase of matter?

Question mark2.svg
[edit] Some definitions

Every field theory of particle physics is based on certain symmetries of nature whose existence is deduced from observations. These can be

local symmetries, that is the symmetry acts independently at each point in space-time. Each such symmetry is the basis of a gauge theory and requires the introduction of its own gauge bosons.
global symmetries, which are symmetries whose operations must be simultaneously applied to all points of space-time.

QCD is a gauge theory of the SU(3) gauge group obtained by taking the color charge to define a local symmetry.

Since the strong interaction does not discriminate between different flavors of quark, QCD has approximate flavor symmetry, which is broken by the differing masses of the quarks.

There are additional global symmetries whose definitions require the notion of chirality, discrimination between left and right-handed. If the spin of a particle has a positive projection on its direction of motion then it is called left-handed; otherwise, it is right-handed. Chirality and handedness are not the same, but become approximately equivalent at high energies.

Chiral symmetries involve independent transformations of these two types of particle.
Vector symmetries (also called diagonal symmetries) mean the same transformation is applied on the two chiralities.
Axial symmetries are those in which one transformation is applied on left-handed particles and the inverse on the right-handed particles.

[edit] Additional remarks: duality

As mentioned, asymptotic freedom means that at large energy - this corresponds also to short distances - there is practically no interaction between the particles. This is in contrast - more precisely one would say dual - to what one is used to, since usually one connects the absence of interactions with large distances. However, as already mentioned in the original paper of Franz Wegner,[9] a solid state theorist who introduced 1971 simple gauge invariant lattice models, the high-temperature behaviour of the original model, e.g. the strong decay of correlations at large distances, corresponds to the low-temperature behaviour of the (usually ordered!) dual model, namely the asymptotic decay of non-trivial correlations, e.g. short-range deviations from almost perfect arrangements, for short distances. Here, in contrast to Wegner, we have only the dual model, which is that one described in this article.[10]
[edit] Symmetry groups

The color group SU(3) corresponds to the local symmetry whose gauging gives rise to QCD. The electric charge labels a representation of the local symmetry group U(1) which is gauged to give QED: this is an abelian group. If one considers a version of QCD with Nf flavors of massless quarks, then there is a global (chiral) flavor symmetry group SU_L(N_f)\times SU_R(N_f)\times U_B(1)\times U_A(1). The chiral symmetry is spontaneously broken by the QCD vacuum to the vector (L+R) SUV(Nf) with the formation of a chiral condensate. The vector symmetry, UB(1) corresponds to the baryon number of quarks and is an exact symmetry. The axial symmetry UA(1) is exact in the classical theory, but broken in the quantum theory, an occurrence called an anomaly. Gluon field configurations called instantons are closely related to this anomaly.

There are two different types of SU(3) symmetry: there is the symmetry that acts on the different colors of quarks, and this is an exact gauge symmetry mediated by the gluons, and there is also a flavor symmetry which rotates different flavors of quarks to each other, or flavor SU(3). Flavor SU(3) is an approximate symmetry of the vacuum of QCD, and is not a fundamental symmetry at all. It is an accidental consequence of the small mass of the three lightest quarks.

In the QCD vacuum there are vacuum condensates of all the quarks whose mass is less than the QCD scale. This includes the up and down quarks, and to a lesser extent the strange quark, but not any of the others. The vacuum is symmetric under SU(2) isospin rotations of up and down, and to a lesser extent under rotations of up, down and strange, or full flavor group SU(3), and the observed particles make isospin and SU(3) multiplets.

The approximate flavor symmetries do have associated gauge bosons, observed particles like the rho and the omega, but these particles are nothing like the gluons and they are not massless. They are emergent gauge bosons in an approximate string description of QCD.
[edit] Lagrangian

The dynamics of the quarks and gluons are controlled by the quantum chromodynamics Lagrangian. The gauge invariant QCD Lagrangian is

\begin{align} \mathcal{L}_\mathrm{QCD} & = \bar{\psi}_i\left(i \gamma^\mu (D_\mu)_{ij} - m\, \delta_{ij}\right) \psi_j - \frac{1}{4}G^a_{\mu \nu} G^{\mu \nu}_a \\ & = \bar{\psi}_i (i \gamma^\mu \partial_\mu - m )\psi_i - g G^a_\mu \bar{\psi}_i \gamma^\mu T^a_{ij} \psi_j - \frac{1}{4}G^a_{\mu \nu} G^{\mu \nu}_a \,,\\ \end{align}

where \psi_i(x) \, is the quark field, a dynamical function of space-time, in the fundamental representation of the SU(3) gauge group, indexed by i,\,j,\,\ldots; G^a_\mu(x) \, are the gluon fields, also a dynamical function of space-time, in the adjoint representation of the SU(3) gauge group, indexed by a,\,b,\,\ldots . The \gamma^\mu \, are Dirac matrices connecting the spinor representation to the vector representation of the Lorentz group; and T^a_{ij} \, are the generators connecting the fundamental, antifundamental and adjoint representations of the SU(3) gauge group. The Gell-Mann matrices provide one such representation for the generators.

The symbol G^a_{\mu \nu} \, represents the gauge invariant gluonic field strength tensor, analogous to the electromagnetic field strength tensor, F^{\mu \nu} \,, in Electrodynamics. It is given by

G^a_{\mu \nu} = \partial_\mu G^a_{\nu} - \partial_\nu G^a_\mu - g f^{abc} G^b_\mu G^c_\nu \,,

where f_{abc} \, are the structure constants of SU(3). Note that the rules to move-up or pull-down the a, b, or c indexes are trivial, (+......+), so that f^{abc}=f_{abc}=f^a_{bc}\,, whereas for the μ or ν indexes one has the non-trivial relativistic rules, corresponding e.g. to the signature (+---). Furthermore, for mathematicians, according to this formula the gluon colour field can be represented by a SU(3)-Lie algebra-valued "curvature"-2-form \mathbf G=\mathrm d\mathbf {\tilde G}-g\,\mathbf {\tilde G}\wedge \mathbf {\tilde G}\,, where \mathbf {\tilde G} is a "vector potential"-1-form corresponding to \mathbf G and \wedge is the (antisymmetric) "wedge product" of this algebra, producing the "structure constants" fabc. The Cartan-derivative of the field form (i.e. essentially the divergence of the field) would be zero in the absence of the "gluon terms", i.e. those ~ g, which represent the non-abelian character of the SU(3).

The constants m and g control the quark mass and coupling constants of the theory, subject to renormalization in the full quantum theory.

An important theoretical notion concerning the final term of the above Lagrangian is the Wilson loop variable. This loop variable plays a most-important role in discretized forms of the QCD (see lattice QCD), and more generally, it distinguishes confined and deconfined states of a gauge theory. It was introduced by the Nobel prize winner Kenneth G. Wilson and is treated in a separate article.
[edit] Fields

Quarks are massive spin-1/2 fermions which carry a color charge whose gauging is the content of QCD. Quarks are represented by Dirac fields in the fundamental representation 3 of the gauge group SU(3). They also carry electric charge (either -1/3 or 2/3) and participate in weak interactions as part of weak isospin doublets. They carry global quantum numbers including the baryon number, which is 1/3 for each quark, hypercharge and one of the flavor quantum numbers.

Gluons are spin-1 bosons which also carry color charges, since they lie in the adjoint representation 8 of SU(3). They have no electric charge, do not participate in the weak interactions, and have no flavor. They lie in the singlet representation 1 of all these symmetry groups.

Every quark has its own antiquark. The charge of each antiquark is exactly the opposite of the corresponding quark.
[edit] Dynamics

According to the rules of quantum field theory, and the associated Feynman diagrams, the above theory gives rise to three basic interactions: a quark may emit (or absorb) a gluon, a gluon may emit (or absorb) a gluon, and two gluons may directly interact. This contrasts with QED, in which only the first kind of interaction occurs, since photons have no charge. Diagrams involving Faddeev–Popov ghosts must be considered too.
[edit] Area law and confinement

Detailed computations with the above-mentioned Lagrangian[11] show that the effective potential between a quark and its anti-quark in a meson contains a term \propto r, which represents some kind of "stiffness" of the interaction between the particle and its anti-particle at large distances, similar to the entropic elasticity of a rubber band (see below). This leads to confinement [12] of the quarks to the interior of hadrons, i.e. mesons and nucleons, with typical radii Rc, corresponding to former "Bag models" of the hadrons[13] . The order of magnitude of the "bag radius" is 1 fm (=10−15 m). Moreover, the above-mentioned stiffness is quantitatively related to the so-called "area law" behaviour of the expectation value of the Wilson loop product \,P_W of the ordered coupling constants around a closed loop W; i.e. \,\langle P_W\rangle is proportional to the area enclosed by the loop. For this behaviour the non-abelian behaviour of the gauge group is essential.
[edit] Methods

Further analysis of the content of the theory is complicated. Various techniques have been developed to work with QCD. Some of them are discussed briefly below.
[edit] Perturbative QCD

This approach is based on asymptotic freedom, which allows perturbation theory to be used accurately in experiments performed at very high energies. Although limited in scope, this approach has resulted in the most precise tests of QCD to date.
[edit] Lattice QCD
Main article: Lattice QCD

Among non-perturbative approaches to QCD, the most well established one is lattice QCD. This approach uses a discrete set of space-time points (called the lattice) to reduce the analytically intractable path integrals of the continuum theory to a very difficult numerical computation which is then carried out on supercomputers like the QCDOC which was constructed for precisely this purpose. While it is a slow and resource-intensive approach, it has wide applicability, giving insight into parts of the theory inaccessible by other means. However, the numerical sign problem makes it difficult to use lattice methods to study QCD at high density and low temperature (e.g. nuclear matter or the interior of neutron stars).
[edit] 1/N expansion
Main article: 1/N expansion

A well-known approximation scheme, the 1/N expansion, starts from the premise that the number of colors is infinite, and makes a series of corrections to account for the fact that it is not. Until now it has been the source of qualitative insight rather than a method for quantitative predictions. Modern variants include the AdS/CFT approach.
[edit] Effective theories

For specific problems effective theories may be written down which give qualitatively correct results in certain limits. In the best of cases, these may then be obtained as systematic expansions in some parameter of the QCD Lagrangian. One such effective field theory is chiral perturbation theory or ChiPT, which is the QCD effective theory at low energies. More precisely, it is a low energy expansion based on the spontaneous chiral symmetry breaking of QCD, which is an exact symmetry when quark masses are equal to zero, but for the u,d and s quark, which have small mass, it is still a good approximate symmetry. Depending on the number of quarks which are treated as light, one uses either SU(2) ChiPT or SU(3) ChiPT . Other effective theories are heavy quark effective theory (which expands around heavy quark mass near infinity), and soft-collinear effective theory (which expands around large ratios of energy scales). In addition to effective theories, models like the Nambu-Jona-Lasinio model and the chiral model are often used when discussing general features.
[edit] QCD Sum Rules
Main article: QCD sum rules

Based on an Operator product expansion one can derive sets of relations that connect different observables with each other.
[edit] Nambu-Jona-Lasinio model

A recent work by Kei-Ichi Kondo shows that the proper low-energy limit for QCD is a Nambu-Jona-Lasinio model extended to a Polyakov-Nambu-Jona-Lasinio model at finite temperature[14].
[edit] Experimental tests

The notion of quark flavours was prompted by the necessity of explaining the properties of hadrons during the development of the quark model. The notion of colour was necessitated by the puzzle of the Δ++
. This has been dealt with in the section on the history of QCD.

The first evidence for quarks as real constituent elements of hadrons was obtained in deep inelastic scattering experiments at SLAC. The first evidence for gluons came in three jet events at PETRA.

Good quantitative tests of perturbative QCD are

the running of the QCD coupling as deduced from many observations
scaling violation in polarized and unpolarized deep inelastic scattering
vector boson production at colliders (this includes the Drell-Yan process)
jet cross sections in colliders
event shape observables at the LEP
heavy-quark production in colliders

Quantitative tests of non-perturbative QCD are fewer, because the predictions are harder to make. The best is probably the running of the QCD coupling as probed through lattice computations of heavy-quarkonium spectra. There is a recent claim about the mass of the heavy meson Bc [4]. Other non-perturbative tests are currently at the level of 5% at best. Continuing work on masses and form factors of hadrons and their weak matrix elements are promising candidates for future quantitative tests. The whole subject of quark matter and the quark-gluon plasma is a non-perturbative test bed for QCD which still remains to be properly exploited.
[edit] Cross-relations to Solid State Physics

There are unexpected cross-relations to solid state physics. For example, the notion of gauge invariance forms the basis of the well-known Mattis spin glasses,[15] which are systems with the usual spin degrees of freedom s_i=\pm 1\, for i =1,...,N, with the special fixed "random" couplings J_{i,k}=\epsilon_i \,J_0\,\epsilon_k\,. Here the εi and εk quantities can independently and "randomly" take the values \pm 1, which corresponds to a most-simple gauge transformation (\,s_i\to s_i\cdot\epsilon_i\quad\,J_{i,k}\to \epsilon_i J_{i,k}\epsilon_k\,\quad s_k\to s_k\cdot\epsilon_k \,)\,. This means that thermodynamic expectation values of measurable quantities, e.g. of the energy {\mathcal H}:=-\sum s_i\,J_{i,k}\,s_k\,, are invariant.

However, here the coupling degrees of freedom Ji,k, which in the QCD correspond to the gluons, are "frozen" to fixed values (quenching). In contrast, in the QCD they "fluctuate" (annealing), and through the large number of gauge degrees of freedom the entropy plays an important role (see below).

For positive J0 the thermodynamics of the Mattis spin glass corresponds in fact simply to a ferromagnet, just because these systems have no "frustration“ at all. This term is a basic measure in spin glass theory.[16] Quantitatively it is identical with the loop-product P_W:\,=\,J_{i,k}J_{k,l}...J_{n,m}J_{m,i} along a closed loop W. However, for a Mattis spin glass - in contrast to "genuine" spin glasses - the quantity PW never becomes negative.

The basic notion "frustration" of the spin-glass is actually similar to the Wilson loop quantity of the QCD. The only difference is again that in the QCD one is dealing with SU(3) matrices, and that one is dealing with a "fluctuating" quantity. Energetically, perfect absence of frustration should be non-favorable and atypical for a spin glass, which means that one should add the loop-product to the Hamiltonian, by some kind of term representing a "punishment". - In the QCD the Wilson loop is essential for the Lagrangian rightaway.

The relation between the QCD and "disordered magnetic systems" (the spin glasses belong to them) were additionally stressed in a paper by Fradkin, Huberman und Shenker,[17] which also stresses the notion of duality.

A further analogy consists in the already mentioned similarity to polymer physics, where, analogously to Wilson Loops, so-called "entangled nets" appear, which are important for the formation of the entropy-elasticity (force proportional to the length) of a rubber band. The non-abelian character of the SU(3) corresponds thereby to the non-trivial "chemical links“, which glue different loop segments together, and "asymptotic freedom" means in the polymer analogy simply the fact that in the short-wave limit, i.e. for 0\leftarrow\lambda_w\ll R_c (where Rc is a characteristic correlation-length for the glued loops, corresponding to the above-mentioned "bag radius", while λw is the wavelength of an excitation) any non-trivial correlation vanishes totally, as if the system had crystallized.[18]

There is also a correspondence between confinement in QCD - the fact that the colour-field is only different from zero in the interior of hadrons - and the behaviour of the usual magnetic field in the theory of type-II superconductors: there the magnetism is confined to the interiour of the Abrikosov flux-line lattice,[19] i.e., the London penetration depth λ of that theory is analogous to the confinement radius Rc of quantum chromodynamics. Mathematically, this correspondendence is supported by the second term, \propto g G^a_\mu \bar{\psi}_i \gamma^\mu T^a_{ij} \psi_j\,, on the r.h.s. of the Lagrangian.
[edit] See also

For overviews, see Standard Model, its field theoretical formulation, strong interactions, quarks and gluons, hadrons, confinement, QCD matter, or quark-gluon plasma.
For details, see gauge theory, quantization procedure including BRST quantization and Faddeev–Popov ghosts. A more general category is quantum field theory.
For techniques, see Lattice QCD, 1/N expansion, perturbative QCD, Soft-collinear effective theory, heavy quark effective theory, chiral models, and the Nambu and Jona-Lasinio model.
For experiments, see quark search experiments, deep inelastic scattering, jet physics, quark-gluon plasma.

[edit] References

^ Gell-Mann, Murray (1995). The Quark and the Jaguar. Owl Books. ISBN 978-0805072532.
^ Fyodor Tkachov (2009). "A contribution to the history of quarks: Boris Struminsky's 1965 JINR publication". arXiv:0904.0343 [physics.hist-ph].
^ a b B. V. Struminsky, Magnetic moments of barions in the quark model. JINR-Preprint P-1939, Dubna, Russia. Submitted on January 7, 1965.
^ N. Bogolubov, B. Struminsky, A. Tavkhelidze. On composite models in the theory of elementary particles. JINR Preprint D-1968, Dubna 1965.
^ A. Tavkhelidze. Proc. Seminar on High Energy Physics and Elementary Particles, Trieste, 1965, Vienna IAEA, 1965, p. 763.
^ V. A. Matveev and A. N. Tavkhelidze (INR, RAS, Moscow) The quantum number color, colored quarks and QCD (Dedicated to the 40th Anniversary of the Discovery of the Quantum Number Color). Report presented at the 99th Session of the JINR Scientific Council, Dubna, 19–20 January 2006.
^ J. Polchinski, M. Strassler (2002). "Hard Scattering and Gauge/String duality". Physical Review Letters 88 (3): 31601. arXiv:hep-th/0109174. Bibcode 2002PhRvL..88c1601P. doi:10.1103/PhysRevLett.88.031601. PMID 11801052.
^ Brower, Richard C.; Mathur, Samir D.; Chung-I Tan (2000). "Glueball Spectrum for QCD from AdS Supergravity Duality". arXiv:hep-th/0003115 [hep-th].
^ F. Wegner, Duality in Generalized Ising Models and Phase Transitions without Local Order Parameter, J. Math. Phys. 12 (1971) 2259-2272.

Reprinted in Claudio Rebbi (ed.), Lattice Gauge Theories and Monte Carlo Simulations, World Scientific, Singapore (1983), p. 60-73. Abstract: [1]

^ Perhaps one can guess that in the "original" model mainly the quarks would fluctuate, whereas in the present one, the "dual" model, mainly the gluons do.
^ See all standard textbooks on the QCD, e.g., those noted above
^ Only at extremely large pressures and or temperatures, e.g. for T\cong 5\cdot 10^{12} K or larger, confinement gives way to a quark-gluon plasma.
^ Kenneth A. Johnson, The bag model of quark confinement, Scientific American, July 1979
^ Kei-Ichi Kondo (2010). "Toward a first-principle derivation of confinement and chiral-symmetry-breaking crossover transitions in QCD". Physical Review D 82: 065024. arXiv:1005.0314v2. doi:10.1103/PhysRevD.82.065024.
^ D.C. Mattis, Phys. Lett. 56a (1976) 421
^ J. Vanninemus and G. Toulouse, J. Phys. C 10 (1977) 537
^ E. Fradkin, B.A. Huberman, S. Shenker, Gauge Symmetries in random magnetic systems, Phys. Rev. B 18 (1978) 4783-4794, [2]
^ A. Bergmann, A. Owen , Dielectric relaxation spectroscopy of poly[(R)-3-Hydroxybutyrate] (PHD) during crystallization, Polymer International 53 (7) (2004) 863-868, [3]
^ Mathematically, the flux-line lattices are described by Emil Artin's braid group, which is nonabelian, since one braid can wind around another one.

[edit] Further reading

Greiner, Walter;Schäfer, Andreas (1994). Quantum Chromodynamics. Springer. ISBN 0-387-57103-5.
Halzen, Francis; Martin, Alan (1984). Quarks & Leptons: An Introductory Course in Modern Particle Physics. John Wiley & Sons. ISBN 0-471-88741-2.
Creutz, Michael (1985). Quarks, Gluons and Lattices. Cambridge University Press. ISBN 978-0521315357.

[edit] External links

Particle data group
The millennium prize for proving confinement
Ab Initio Determination of Light Hadron Masses
Andreas S Kronfeld The Weight of the World Is Quantum Chromodynamics
Andreas S Kronfeld Quantum chromodynamics with advanced computing
Standard model gets right answer
Quantum Chromodynamics

[SpursFanInAustin]

Wow, Duncan's overrated because he's a 7 ft power forward and has height advantage? I guess Magic Johnson was an overrated PG cause he was 6'9.

[cd98]

Here is the most overrated legend of our times, Mr Fundamentals; or should I say Mr Opportunity. Duncan is a solid all around player there is no denying that, but for anyone who remembers the NBA beyond 2000 you know that Duncan is not as good as everyone says he is. For starters he is a center who was converted to power forward because the Spurs had David Robinson. Duncan stand at about seven feet, the modern power forward today averages about six foot eight inches, which means Duncan has a good four inches on them.

The rules of today’s game have also helped Duncan a lot. In a game were defense is all but abolished, a player with little offensive skills can look really good because they can’t be touched. If Duncan played in the early 90s, he would be nothing more than a sixth man defensive plug.

Sorry, but this is bad analysis.

First, during the Duncan era of domination, the best players in the league were all power forwards and they were all tall. Look at the players he competed against: Chris Webber, Rasheed Wallace, Kevin Garnett, Elton Brand, Karl Malone (won an MVP the year before Tim's first), Amare Stoudemire, Carolos Boozer, Antonio McDyess, Jermaine O'Neal (his best years), Paul Gasol, Dirk Nowitzki, Dennis Rodman. He didn't have any significant height advantage over most of these players and he was double teamed when going up against them. True, the modern power forwards are smaller (by today's standards), but that wasn't true during Duncan's era of domination.

Plus you are dead wrong on the rule change. The rule change helps speedy guards, not post players. If anything, it enhances the likelihood that big post players will get in foul trouble, something that a great defensive player like Duncan rarely had happen.

If anything, Duncan is underrated.

[lefty]

TBH, if Duncan actually got his wish and played PG, he would have averaged 75 ppg, 22 apg, 28 rpg, 11 bpg and 8 spg on 74 FG% shooting because he would have a 9 inch advantage against his average competition.
Ouch Magic Johnson :lol

Inch for inch, Isiah shits on Earvin

And much more, not that there is anything wrong with that

[Dunc n Dave]

Ouch Magic Johnson :lol

Inch for inch, Isiah shits on Earvin

And much more, not that there is anything wrong with that

Agreed... Magic was overrated as a rebounder at PG especially. It's easy to grab alot of rebounds when you have a 6 to 8" height advantage over other point guards in the league. Hell, he shoulda grabbed 40 rebounds every game when matched up against guys like Muggsy Bogues, Spudd Webb, and Michael Adams. He was nearly a foot taller than most of those guys....

Damn, this is GREAT logic!

[lefty]

Agreed... Magic was overrated as a rebounder at PG especially. It's easy to grab alot of rebounds when you have a 6 to 8" height advantage over other point guards in the league. Hell, he shoulda grabbed 40 rebounds every game when matched up against guys like Muggsy Bogues, Spudd Webb, and Michael Adams. He was nearly a foot taller than most of those guys....

Damn, this is GREAT logic!
:lol

But as a passer, his height did help him to look over smaller defenders

[Dunc n Dave]

:lol

But as a passer, his height did help him to look over smaller defenders

You're right! I'm gonna have to look up the games he played against guys under 6 feet. If he didn't avaergae at LEAST 40 boards and 20 assists in those games, they should remove Magic from the HOF, PRONTO!

[Dunc n Dave]

Looked up the games Magic Johnson played against Muggsy Bogues (5'3"), Michael Adams (5'10"), and Spud Webb (5'6").

I used the 89-90 season, Magic's last MVP season. He played a total of 10 games versus those 3 pt guards during the season.

Here's the numbers:
10 games played
23 ppg
7.6 rebs
12.2 asts
4.5 TOS

A 6'9" Magic could only muster 7.6 rebs and 12.2 asts against 3 guys who were 11 to 18 inches shorter than him? And 4.5 TOs? For an MVP? Sounds pretty overrated to me...

[lefty]

Looked up the games Magic Johnson played against Muggsy Bogues (5'3"), Michael Adams (5'10"), and Spud Webb (5'6").

I used the 89-90 season, Magic's last MVP season. He played a total of 10 games versus those 3 pt guards during the season.

Here's the numbers:
10 games played
23 ppg
7.6 rebs
12.2 asts
4.5 TOS

A 6'9" Magic could only muster 7.6 rebs and 12.2 asts against 3 guys who were 11 to 18 inches shorter than him? And 4.5 TOs? For an MVP? Sounds pretty overrated to me...

I agree !!!!!!!!

[JayTheClown]

You have to be a complete idiot if believe Tim Duncan was overrated throughout his career.

[Trill Clinton]

http://i745.photobucket.com/albums/xx100/MABOcho/1282855171617.gif

[BRHornet45]

Quality post and 100% truth in everything stated. 90% of NBA fans outside of Texas know the truth. Duncan is good, but far from great and ridiculously overrated. Mr. Opportunity is exactly right.

[Silver&Black]

Here is the most overrated legend of our times, Mr Fundamentals; or should I say Mr Opportunity. Duncan is a solid all around player there is no denying that, but for anyone who remembers the NBA beyond 2000 you know that Duncan is not as good as everyone says he is. For starters he is a center who was converted to power forward because the Spurs had David Robinson. Duncan stand at about seven feet, the modern power forward today averages about six foot eight inches, which means Duncan has a good four inches on them.

The rules of today’s game have also helped Duncan a lot. In a game were defense is all but abolished, a player with little offensive skills can look really good because they can’t be touched. If Duncan played in the early 90s, he would be nothing more than a sixth man defensive plug.

Same could be said about KoMe.

[Blake]

you see a lot of centers do this?

LOL what a fail troll. So players like Duncan are benefiting from the game more today, and not players such as Kobe, Wade and Durant?


Fail.

excellent rebuttal.

the greyness is strong in you.

[GB20]

Here is the most overrated legend of our times, Mr Fundamentals; or should I say Mr Opportunity. Duncan is a solid all around player there is no denying that, but for anyone who remembers the NBA beyond 2000 you know that Duncan is not as good as everyone says he is. For starters he is a center who was converted to power forward because the Spurs had David Robinson. Duncan stand at about seven feet, the modern power forward today averages about six foot eight inches, which means Duncan has a good four inches on them.

The rules of today’s game have also helped Duncan a lot. In a game were defense is all but abolished, a player with little offensive skills can look really good because they can’t be touched. If Duncan played in the early 90s, he would be nothing more than a sixth man defensive plug.
give me a fucking brake man!! if both tim duncan and kobe were twenty years old, who would you pick to build a team?

[Spurtacus]

4 rings = overrated

:lmao

[Spursfan092120]

http://i745.photobucket.com/albums/xx100/MABOcho/1282855171617.gif

lol...Vince...the ultimate "I don't give a fuck" mofo..

[DMC]

give me a fucking brake man!! if both tim duncan and kobe were twenty years old, who would you pick to build a team?
http://www.atozmotorspares.co.uk/suppliers/mintexpads.jpg

[DMC]

What makes Duncan overrated is people overrating him tbh fwiw imo ftw.

[Frenzy]

What makes Duncan overrated is people overrating him tbh fwiw imo ftw.

This iirc

[007nites]

He's right, Duncan is overrated.

His whole career has been a fluke. The four championships he won were won by Robinson, Parker, and Ginobili. If Duncan wasn't on the team the Spurs would have had 7 Championships already. The only reason he got on the All Defensive team 10+ times was because Parker and Ginobili were letting there opponents fly by them on purpose so that Duncan could pad his blocking stats. Also, the only reason he averaged 20 and 10 throughout his career is because he was a ball hog and took 25 shots per a game to keep his 20 point per average up. Oh did I forget, his rebounding stats are over inflated because Bowen was such a good defender that off his opponents missed shots Duncan took the opportunity to cash in on easy rebounds. Also, during those first 2 championships Robinson was a beast, dude was carrying the team on his back even though he was barely averaging 10 points and 8 rebounds. Robinson was itimidating the hell out of Shaq so much that Duncan was able to go for 20+ points, 14+ rebounds, 4+ assists, and 4+ blocks during the playoffs which proves that he's overrated. The only reason the Spurs won in the 2003 Finals was because Robinson, Parker, and Ginobili were beasting on the Nets. They would have swept the Nets without Duncan. Overall, Duncan is shit and all of the NBA fans overrate the hell out of him by talking about him on a day to day bases. All of these kids I hear talking about how Duncan is the best and how he does all these cool things on the basketball court which makes him stand out from the rest. Also, I'm sick of hearing these comparisons towards Duncan and Lebron. Duncan is a PF for god sakes you can't compare a PF to a SF. Thats two different positions!

[Lincoln]

He's right, Duncan is overrated.

His whole career has been a fluke. The four championships he won were won by Robinson, Parker, and Ginobili. If Duncan wasn't on the team the Spurs would have had 7 Championships already. The only reason he got on the All Defensive team 10+ times was because Parker and Ginobili were letting there opponents fly by them on purpose so that Duncan could pad his blocking stats. Also, the only reason he averaged 20 and 10 throughout his career is because he was a ball hog and took 25 shots per a game to keep his 20 point per average up. Oh did I forget, his rebounding stats are over inflated because Bowen was such a good defender that off his opponents missed shots Duncan took the opportunity to cash in on easy rebounds. Also, during those first 2 championships Robinson was a beast, dude was carrying the team on his back even though he was barely averaging 10 points and 8 rebounds. Robinson was itimidating the hell out of Shaq so much that Duncan was able to go for 20+ points, 14+ rebounds, 4+ assists, and 4+ blocks during the playoffs which proves that he's overrated. The only reason the Spurs won in the 2003 Finals was because Robinson, Parker, and Ginobili were beasting on the Nets. They would have swept the Nets without Duncan.

Cool story brah

[spursfan09]

If anything, when you create a thread like this, you are just really underrating him.

[dbreiden83080]

http://blog.cleveland.com/livingston_impact/2009/05/medium_duncanms.jpg

http://4.bp.blogspot.com/_ORir7eN3-j8/TQcVYZ482WI/AAAAAAAAAPQ/GJr1I1hpPl8/s1600/david-robinson-tim-duncan.jpg

http://nbcprobasketballtalk.files.wordpress.com/2010/09/tx.tim.duncan.mvp.getty-thumb-250x341-20547.jpg?w=250&h=341


http://athletics.williams.edu/images/mbkb/2007-2008/Spurs2.jpg?max_width=450


Over-Rated Indeed...

[Blake]

lol...Vince

lol

[KobeOwnsDuncan]

http://blog.cleveland.com/livingston_impact/2009/05/medium_duncanms.jpg

http://4.bp.blogspot.com/_ORir7eN3-j8/TQcVYZ482WI/AAAAAAAAAPQ/GJr1I1hpPl8/s1600/david-robinson-tim-duncan.jpg

http://nbcprobasketballtalk.files.wordpress.com/2010/09/tx.tim.duncan.mvp.getty-thumb-250x341-20547.jpg?w=250&h=341


http://athletics.williams.edu/images/mbkb/2007-2008/Spurs2.jpg?max_width=450


Over-Rated Indeed...

1999 - http://cdn.bleacherreport.net/images_root/slides/photos/000/342/650/Avery-Johnson-s-championship-winning-shot-vs-Knicks-san-antonio-spurs-8857660-627-450_display_image.jpg?1281728698


http://a.espncdn.com/photo/2007/1222/nba_a_johnson_300.jpg

Mr Robinson

1998-1999 15.8 ppg, 10 rpg, 2.1 apg, 2.4 bpg, 1.4 spg, 50.9 FG%, 31.7 mpg
Playoffs 15.6 ppg, 9.9 rpg, 2.5 apg, 2.4 bpg, 1.7 spg, 48.3 FG%
Finals- 17 ppg, 11.8 rpg, 2.4 apg, 3 bpg, 1 spg, 44.1 FG%

[KobeOwnsDuncan]

Spurfan: "Duncan is NOT overrated but Ginobli should be in the HOF"

:lmao

[Leetonidas]

people are replying so I win!! i troll you lololololol

[lefty]

http://images.cheezburger.com/completestore/2011/6/20/be2c8d9d-a4e4-4b36-a0c0-bd19fa794210.jpg

[pass1st]

People call him the best PF ever, which makes you think it's overrating since you have the likes of Malone and Barkley in the mix. Duncan, however, does have something to show for his effort. You can argue that he never had to deal with the likes of the Jordan-Pippen Bulls.

All in all, what NBA star isn't overrated? Even Jordan is overrated, people think he would average 50 points in this era.

[LkrFan]

If Timmy D played in the '80s, his ceiling is Brad Daughtery. Good skilled, fundamentally sound player, but not great. No shame in that.

To think Timmy D would dominate in the '80s is wishful thinking. That was a rough and tumble era. Not too many stars of today could have played at the same elite level they enjoy in today's NBA. So he's not alone.

[Dunc n Dave]

If Timmy D played in the '80s, his ceiling is Brad Daughtery. Good skilled, fundamentally sound player, but not great. No shame in that.

To think Timmy D would dominate in the '80s is wishful thinking. That was a rough and tumble era. Not too many stars of today could have played at the same elite level they enjoy in today's NBA. So he's not alone.

Sure, as long as you recognize that Kobe's ceiling would've been Ron Harper in the 80s. Gifted athlete, but always injured and dropped off hard at age 30 because of the beatings he would take on his way to the rack. Perhaps he could've even been one of Jordan's role players helping him to a couple championships as a 4th or 5th option, like Harper too.

[DMC]

If Timmy D played in the '80s, his ceiling is Brad Daughtery. Good skilled, fundamentally sound player, but not great. No shame in that.

To think Timmy D would dominate in the '80s is wishful thinking. That was a rough and tumble era. Not too many stars of today could have played at the same elite level they enjoy in today's NBA. So he's not alone.
Thank you Bob Costas.

[dbreiden83080]

:lol

1998-1999 15.8 ppg, 10 rpg, 2.1 apg, 2.4 bpg, 1.4 spg, 50.9 FG%, 31.7 mpg
Playoffs 15.6 ppg, 9.9 rpg, 2.5 apg, 2.4 bpg, 1.7 spg, 48.3 FG%
Finals- 17 ppg, 11.8 rpg, 2.4 apg, 3 bpg, 1 spg, 44.1 FG%



Duncan 1999 NBA Finals 27.4 PPG 14.0 RPG 54% FG

And



What's that he's holding there? :lol


http://cdn.bleacherreport.net/images_root/slideshows/510/slideshow_51003/display_image.jpg?x=317917

[LkrFan]

Sure, as long as you recognize that Kobe's ceiling would've been Ron Harper in the 80s. Gifted athlete, but always injured and dropped off hard at age 30 because of the beatings he would take on his way to the rack. Perhaps he could've even been one of Jordan's role players helping him to a couple championships as a 4th or 5th option, like Harper too.

If anything Wade would have been Harper (who was DAMN good BTW before the injuries). Why you ask? Because he doesn't have a consistent jumper and goes to the hole with wreckless abandone. Kobe has a consistent jumper and does not need to do all that. He does not have to make SportsCenter every night dunking every chance he gets to still be effective.

[LkrFan]

Thank you Bob Costas.

Can you honestly say TD and Brad's games aren't similar? Both have a lot of finesse in their games. As a result, Brad got his shit pushed in early and often during the brutal EC playoffs by the likes of the Bulls, Knicks or 6ers. TD would have been no different.

Why would we expect TD to dominate the Bad Boys when Brad couldn't? :downspin:

[dbreiden83080]

Can you honestly say TD and Brad's games aren't similar?:

Yeah one guy was mediocre

the other was great...

[Bill_Brasky]

Duncan has been so great that people have to make up hypothetical situations to try and hate on him. People don't do that with other players.

GOAT?

[LkrFan]

Yeah one guy was mediocre

the other was great...



Would he have been great against these guys in the '80s?

Bill Laimbeer
Rick Mahorn
The Worm
Charles Oakley
Karl Malone (in the 80's when he was allowed to be physical. Remember when he knocked out the Admiral? I know you do! :lol)
Charles Barkley
Ewing
Moses Malone
Artis Gilmore (The A-Train)
Even 50 year old Kareem (just ask Bird :lol)
Bill Cartwright
Any of these guys would have more than put Timid's dick in the dirt with that weak ass finesse shit. The '80s was no punk. Timid would not have been great in the '80s. Brad Daughtery at best like I said. :downspin:


Now Malone doesn't have the hardware, but it is not because he wasn't great. His game was born in the rough and tumble '80s. He kicked ass and took names. He would have rang a couple of times in the '80s if not for "Showtime" standing in his way. You guys call Timmy D the goat? Well he didn't win shit until Malone's 14th year in the league and even then it wasn't a slam dunk.

Rings matter, but you Spur fans need to respect how the Mailman delivered for over 20 years. Especially considering how the wheels fell off for Timmy D after his 15th. We don't call him tired old shit bag for nothing around these parts. :lol

:toast

[DMC]

Can you honestly say TD and Brad's games aren't similar? Both have a lot of finesse in their games. As a result, Brad got his shit pushed in early and often during the brutal EC playoffs by the likes of the Bulls, Knicks or 6ers. TD would have been no different.

Thank you Colter Stevens, knower of parallel universes and other outcomes.



Why would we expect TD to dominate the Bad Boys when Brad couldn't? :downspin:

Ask them. They are the ones calling TD the best PF to ever play the game.

[LkrFan]

Thank you Colter Stevens, knower of parallel universes and other outcomes.


Ask them. They are the ones calling TD the best PF to ever play the game.

DMC with the bads. Way to pick which part of my post you want to :downspin:. In the '80s TD would be considered soft. In the 2000s he's on the endangered big man's list: protected status. :lol

[DMC]

would he have been great against these guys in the '80s?

bill laimbeer
rick mahorn
the worm
charles oakley
karl malone (in the 80's when he was allowed to be physical. Remember when he knocked out the admiral? I know you do! :lol)
charles barkley
ewing
moses malone
artis gilmore (the a-train)
even 50 year old kareem (just ask bird :lol)
bill cartwright

any of these guys would have more than put timid's dick in the dirt with that weak ass finesse shit. The '80s was no punk. Timid would not have been great in the '80s. Brad daughtery at best like i said. :downspin:


Now malone doesn't have the hardware, but it is not because he wasn't great. His game was born in the rough and tumble '80s. He kicked ass and took names. He would have rang a couple of times in the '80s if not for "showtime" standing in his way. You guys call timmy d the goat? Well he didn't win shit until malone's 14th year in the league and even then it wasn't a slam dunk.

Rings matter, but you spur fans need to respect how the mailman delivered for over 20 years. Especially considering how the wheels fell off for timmy d after his 15th. We don't call him tired old shit bag for nothing around these parts. :lol

:toast

0/10

[LkrFan]

0/10

:downspin:

[Sean Cagney]

Quality post and 100% truth in everything stated. 90% of NBA fans outside of Texas know the truth. Duncan is good, but far from great and ridiculously overrated. Mr. Opportunity is exactly right.

Ehhhh NO I live in VA and they see Tim as a legend here too, two of the biggest faggot haters on this board speak! BBALL players call TIM THE GOAT PF and they are not from TEXAS! Critics and writers as well! You guys must have been snuffed for an auto or he fucked your wives! You two are clowns SONSSSSSSSSSSSSSSS.......:lol

[DMC]

I doubt if Jim fucked someones ol lady. In fact, you can barely imagine him wanting to fuck his ol lady. Which begs the question... is Jim Duncan gay? Kool pointed out that he has a tongue ring, which only fags and dikes sport just to put themselves on notice to the world that they like sucking cock. He has tats in girly areas... Ankle, inner thigh, and the small of his back. You be the judge.

He could be gay.

[DMC]

But at least he's not sporting butterflies carrying a ring.

[J_Paco]

:downspin:

You sir are a moron...........................

This troll thread is laughingly stupid and retarded. Comparing one of the 10 greatest big men/players ever to Bill Cartwright and Brad Daugherty????????????

:rollin:rollin:rollin

Tim Duncan is a multiple-time champion, league MVP, Finals MVP and nothing you trolls on this board changes that. When I hear Bill Russell and damn near every young big man in the game heap praise upon Duncan, then I understand his place in history. He's right there with Hakeem, Shaquille and just underneath Kareem, Wilt and Russell.

[TDfan2007]

TBH, if Duncan actually got his wish and played PG, he would have averaged 75 ppg, 22 apg, 28 rpg, 11 bpg and 8 spg on 74 FG% shooting because he would have a 9 inch advantage against his average competition.

:lol /thread

[ambchang]

Would he have been great against these guys in the '80s?

Bill Laimbeer
Rick Mahorn
The Worm
Charles Oakley
Karl Malone (in the 80's when he was allowed to be physical. Remember when he knocked out the Admiral? I know you do! :lol)
Charles Barkley
Ewing
Moses Malone
Artis Gilmore (The A-Train)
Even 50 year old Kareem (just ask Bird :lol)
Bill Cartwright
Any of these guys would have more than put Timid's dick in the dirt with that weak ass finesse shit. The '80s was no punk. Timid would not have been great in the '80s. Brad Daughtery at best like I said. :downspin:


Now Malone doesn't have the hardware, but it is not because he wasn't great. His game was born in the rough and tumble '80s. He kicked ass and took names. He would have rang a couple of times in the '80s if not for "Showtime" standing in his way. You guys call Timmy D the goat? Well he didn't win shit until Malone's 14th year in the league and even then it wasn't a slam dunk.

Rings matter, but you Spur fans need to respect how the Mailman delivered for over 20 years. Especially considering how the wheels fell off for Timmy D after his 15th. We don't call him tired old shit bag for nothing around these parts. :lol

:toast

Would Kobe have been great against these guys in the '80s?

Joe Dumars
Sidney Moncrief
Mitch Richmond
Rolando Blackman
Isiah Thomas (in the 80's when he was allowed to be physical. Remember when he gave Magic HIV? I know you do! :lol)
Clyde Drexler
Michael Jordan
Andrew Toney
Michael Cooper
Even 50 year old Dr. J (just ask Bird :lol)
Dennis Johnson
Any of these guys would have more than put Kobe in the dirt with that weak ballhog crap. The '80s was no punk. Kobe would not have been great in the '80s. Michael Ray Richardson at best like I said. :downspin:


Now Michael Jordan didn't have hardware in the 80's, but it is not because he wasn't great. His game was born in the rough and tumble '80s. He kicked ass and took names. He would have rang a couple of times in the '80s if not for Magic and Bird standing in his way. You guys call Kobe the goat? Well he didn't win crap until Jordan's 14th year in the league and even then it wasn't a slam dunk.

Rings matter, but you Laker fans need to respect how his Airness delivered for over 15 years. Especially considering how the wheels fell off for Kobe after his 15th. We don't call him tired old shit bag for nothing around these parts. :lol

:toast

[Strike]

Here is the most overrated legend of our times, Mr Fundamentals; or should I say Mr Opportunity. Duncan is a solid all around player there is no denying that, but for anyone who remembers the NBA beyond 2000 you know that Duncan is not as good as everyone says he is. For starters he is a center who was converted to power forward because the Spurs had David Robinson. Duncan stand at about seven feet, the modern power forward today averages about six foot eight inches, which means Duncan has a good four inches on them.

The rules of today’s game have also helped Duncan a lot. In a game were defense is all but abolished, a player with little offensive skills can look really good because they can’t be touched. If Duncan played in the early 90s, he would be nothing more than a sixth man defensive plug.

http://files.sharenator.com/back_in_the_days_trolling_meant_something_RE_Draw_ a_Troll-s470x600-95420.jpg

[LkrFan]

ambchang biting my style. :downspin:
:lol