QCD effective charges from lattice data

Aguilar, A. C.; Binosi, Daniele; Papavassiliou, Joannis

doi:10.1007/jhep07(2010)002

Cited by 81 publications

(40 citation statements)

References 84 publications

(142 reference statements)

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“…The gluon model generates DCSB, which is an important feature of low energy QCD. And it is infrared finite, which is consistent with lattice QCD's results [49,68,69]. The parameters of this model, i.e., m u , m d , D, and ω are determined by fitting the masses and decay constants of pion and kaon.…”

Section: Discussion and Summarysupporting

confidence: 84%

2+1 flavors QCD equation of state at zero temperature within Dyson–Schwinger equations

Yan

Cui

et al. 2015

Int. J. Mod. Phys. A

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Within the framework of Dyson-Schwinger equations (DSEs), we discuss the equation of state (EOS) and quark number densities of 2+1 flavors, that is to say, u, d, and s quarks. The chemical equilibrium and electric charge neutrality conditions are used to constrain the chemical potential of different quarks. The EOS in the cases of 2 flavors and 2+1 flavors are discussed, and the quark number densities, the pressure, and energy density per baryon are also studied. The results show that there is a critical chemical potential for each flavor of quark, at which the quark number density turns to nonzero from 0; and furthermore, the system with 2+1 flavors of quarks is more stable than that with 2 flavors in the system. These discussion may provide some useful information to some research fields, such as the studies related to the QCD phase transitions or compact stars.

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Section: Discussion and Summarysupporting

confidence: 84%

2+1 flavors QCD equation of state at zero temperature within Dyson–Schwinger equations

Yan

Cui

et al. 2015

Int. J. Mod. Phys. A

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“…[329] have been used by Aguilar, Binosi and Papavassiliou [330] to form α gh s from Eq. (4.25), and α gse using the pinch technique.…”

Section: Lattice Results For α S In the Irmentioning

confidence: 99%

“…For example, studies using linear covariant gauges indicate that the gauge-dependence is weak for gauges chosen close to the Landau gauge [231,318,319]. In contrast, Aguilar and collaborators [235,330] have argued that the differences between gauge-dependent and phenomenological (gauge-independent) calculations of α s can be attributed to the choice of gauge. For example, in calculations yielding α s (0) 3 (see Section 5.4), the gluon propagator is typically computed in Landau gauge.…”

Section: Difference In Gauge Choicesmentioning

confidence: 99%

The QCD running coupling

Deur

Brodsky

Téramond

2016

Progress in Particle and Nuclear Physics

273

236

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We review the present theoretical and empirical knowledge for α s , the fundamental coupling underlying the interactions of quarks and gluons in Quantum Chromodynamics (QCD). The dependence of α s (Q 2 ) on momentum transfer Q encodes the underlying dynamics of hadron physics -from color confinement in the infrared domain to asymptotic freedom at short distances. We review constraints on α s (Q 2 ) at high Q 2 , as predicted by perturbative QCD, and its analytic behavior at small Q 2 , based on models of nonperturbative dynamics. In the introductory part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain.In the second, more technical, part of the review, we discuss the behavior of α s (Q 2 ) in the high momentum transfer domain of QCD. We review how α s is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as "Commensurate Scale Relations" which connect the various definitions of the QCD coupling without renormalization-scale ambiguity. We also report recent significant measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the "Principle of Maximum Conformality", which enhances QCD's predictive power by removing the dependence of the predictions for physical observables on the choice of theoretical conventions such as the renormalization scheme. In the last part of the review, we discuss the challenge of understanding the analytic behavior α s (Q 2 ) in the low momentum transfer domain. We survey various theoretical models for the nonperturbative strongly coupled regime, such as the light-front holographic approach to QCD. This new framework predicts the form of the quark-confinement potential underlying hadron spectroscopy and dynamics, and it gives a remarkable connection between the perturbative QCD scale Λ and hadron masses. One can also identify a specific scale Q 0 which demarcates the division between perturbative and nonperturbative QCD. We also review other important methods for computing the QCD coupling, including lattice QCD, the Schwinger-Dyson equations and the GribovZwanziger analysis. After describing these approaches and enumerating their conflicting predictions, we discuss the origin of these discrepancies and how to remedy them. Our aim is not only to review the advances in this difficult area, but also to suggest what could be an optimal definition of α s (Q 2 ) in order to bring better unity to the subject.2

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“…[26] and the corresponding physically motivated fits we use [55]. In the case of the gluon propagator the dashed curve shows a fit featuring an inflection point the origin of which is linked to the presence of ghost loops [17].…”

Section: Numerical Resultsmentioning

confidence: 99%

“…To this end, we use physically motivated fits to the lattice data of [56], whose explicit functional form can be found in [55]. The agreement of these fits with the corresponding lattice data at the renormalization scale µ = 4.3 GeV is shown in figure 4.…”

Section: Jhep09(2014)059mentioning

confidence: 99%

Nonperturbative study of the four gluon vertex

Binosi

Ibañez

Papavassiliou

2014

J. High Energ. Phys.

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In this paper we study the nonperturbative structure of the SU(3) four-gluon vertex in the Landau gauge, concentrating on contributions quadratic in the metric. We employ an approximation scheme where "one-loop" diagrams are computed using fully dressed gluon and ghost propagators, and tree-level vertices. When a suitable kinematical configuration depending on a single momentum scale p is chosen, only two structures emerge: the tree-level four-gluon vertex, and a tensor orthogonal to it. A detailed numerical analysis reveals that the form factor associated with this latter tensor displays a change of sign (zero-crossing) in the deep infrared, and finally diverges logarithmically. The origin of this characteristic behavior is proven to be entirely due to the masslessness of the ghost propagators forming the corresponding ghost-loop diagram, in close analogy to a similar effect established for the three-gluon vertex. However, in the case at hand, and under the approximations employed, this particular divergence does not affect the form factor proportional to the tree-level tensor, which remains finite in the entire range of momenta, and deviates moderately from its naive tree-level value. It turns out that the kinematic configuration chosen is ideal for carrying out lattice simulations, because it eliminates from the connected Green's function all one-particle reducible contributions, projecting out the genuine one-particle irreducible vertex. Motivated by this possibility, we discuss in detail how a hypothetical lattice measurement of this quantity would compare to the results presented here, and the potential interference from an additional tensorial structure, allowed by Bose symmetry, but not encountered within our scheme.

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QCD effective charges from lattice data

Cited by 81 publications

References 84 publications

2+1 flavors QCD equation of state at zero temperature within Dyson–Schwinger equations

2+1 flavors QCD equation of state at zero temperature within Dyson–Schwinger equations

The QCD running coupling

Nonperturbative study of the four gluon vertex

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