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Furui, Eisuke; Hanzawa, Kazuhiko; Nakajima, Takashi; Fukuhara, Nobuyoshi; Komai, Koichiro; Yamada, Masahito

doi:10.2301/neurosonology.13.100

Cited by 32 publications

(66 citation statements)

References 41 publications

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“…This discrepancy could be accounted for by power corrections in 1 q 2 , due to a positive A 2 µ OPE gluon condensate. The presence of such power corrections has also been discussed in [59]. We do not know if there is a direct connection between the condensate A 2 µ that we determine, and A 2 µ OPE…”

Section: Introductionmentioning

confidence: 77%

Gribov parameter and the dimension two gluon condensate in Euclidean Yang-Mills theories in the Landau gauge

et al. 2005

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The local composite operator A 2 µ is added to the Zwanziger action, which implements the restriction to the Gribov region Ω in Euclidean Yang-Mills theories in the Landau gauge. We prove that Zwanziger's action with the inclusion of the operator A 2 µ is renormalizable to all orders of perturbation theory, obeying the renormalization group equations. This allows to study the dimension two gluon condensate A 2 µ by the local composite operator formalism when the restriction to the Gribov region Ω is taken into account. The resulting effective action is evaluated at one-loop order in the MS scheme. We obtain explicit values for the Gribov parameter and for the mass parameter due to A 2 µ , but the expansion parameter turns out to be rather large. Furthermore, an optimization of the perturbative expansion in order to reduce the dependence on the renormalization scheme is performed. The properties of the vacuum energy, with or without the inclusion of the condensate A 2 µ , are investigated. In particular, it is shown that in the original Gribov-Zwanziger formulation, i.e. without the inclusion of the operator A 2 µ , the resulting vacuum energy is always positive at oneloop order, independently from the choice of the renormalization scheme and scale. In the presence of A 2 µ , we are unable to come to a definite conclusion at the order considered. In the MS scheme, we still find a positive vacuum energy, again with a relatively large expansion parameter, but there are renormalization schemes in which the vacuum energy is negative, albeit the dependence on the scheme itself appears to be strong. Concerning the behaviour of the gluon and ghost propagators, we recover the well known consequences of the restriction to the Gribov region, and this in the presence of A 2 µ , i.e. an infrared suppression of the gluon propagator and an enhancement of the ghost propagator. Such a behaviour is in qualitative agreement with the results obtained from the studies of the Schwinger-Dyson equations and from lattice simulations.

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Section: Introductionmentioning

confidence: 77%

Gribov parameter and the dimension two gluon condensate in Euclidean Yang-Mills theories in the Landau gauge

et al. 2005

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“…For each lattice volume V = N 4 = 4 4 , 8 4 , 16 4 we have performed simulations for three lattice couplings (β = 2.2, 2.3, 2.4 ). We consider lattice momenta with componentŝ p 1 =p 2 =p 3 =p 4 =p and p = 2πn/N, where n gets values 1, .…”

Section: Numerical Simulations and Resultsmentioning

confidence: 99%

Numerical Study of the Ghost-Ghost-Gluon Vertex on the Lattice

Mihara¹

2004

AIP Conference Proceedings

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Abstract.It is well known that, in Landau gauge, the renormalization function of the ghost-ghostgluon vertex Z 1 (p 2 ) is finite and constant, at least to all orders of perturbation theory. On the other hand, a direct non-perturbative verification of this result using numerical simulations of lattice QCD is still missing. Here we present a preliminary numerical study of the ghost-ghost-gluon vertex and of its corresponding renormalization function using Monte Carlo simulations in SU(2) lattice Landau gauge. Data were obtained in 4 dimensions for lattice couplings β = 2.2, 2.3, 2.4 and lattice sides N = 4, 8, 16.

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“…Theoretical [55,56,57,58,59] and phenomenological [60,53,61] evidence is now accumulating that the QCD coupling becomes constant at small virtuality; i.e., α s (Q 2 ) develops an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. If QCD running couplings are bounded, the integration over the running coupling is finite and renormalon resummations are not required.…”

Section: Ads/cft and Its Consequences For Near-conformal Field Theorymentioning

confidence: 99%

New Results in Light-Front Phenomenology

Brodsky¹

2004

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The light-front quantization of gauge theories in light-cone gauge provides a frameindependent wavefunction representation of relativistic bound states, simple forms for current matrix elements, explicit unitarity, and a trivial vacuum. In this talk I review the theoretical methods and constraints which can be used to determine these central elements of QCD phenomenology. The freedom to choose the light-like quantization four-vector provides an explicitly covariant formulation of light-front quantization and can be used to determine the analytic structure of light-front wave functions and define a kinematical definition of angular momentum. The AdS/CFT correspondence of large N C supergravity theory in higher-dimensional anti-de Sitter space with supersymmetric QCD in 4-dimensional space-time has interesting implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for exclusive processes. String/gauge duality also predicts the QCD power-law behavior of light-front Fock-state hadronic wavefunctions with arbitrary orbital angular momentum at high momentum transfer. The form of these nearconformal wavefunctions can be used as an initial ansatz for a variational treatment of the light-front QCD Hamiltonian. The light-front Fock-state wavefunctions encode the bound state properties of hadrons in terms of their quark and gluon degrees of freedom at the amplitude level. The nonperturbative Fock state wavefunctions contain intrinsic gluons, and sea quarks at any scale Q with asymmetries such as s(x) =s(x),ū(x) =d(x). Intrinsic charm and bottom quarks appear at large x in the light-front wavefunctions since this minimizes the invariant mass and off-shellness of the higher Fock state. In the case of nuclei, the Fock state expansion contains "hidden color" states which cannot be classified in terms of nucleonic degrees of freedom. I also briefly review recent analyses which shows that some leading-twist phenomena such as the diffractive component of deep inelastic scattering, single-spin asymmetries, nuclear shadowing and antishadowing cannot be computed from the LFWFs of hadrons in isolation.2

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Untitled

Cited by 32 publications

References 41 publications

Gribov parameter and the dimension two gluon condensate in Euclidean Yang-Mills theories in the Landau gauge

Gribov parameter and the dimension two gluon condensate in Euclidean Yang-Mills theories in the Landau gauge

Numerical Study of the Ghost-Ghost-Gluon Vertex on the Lattice

New Results in Light-Front Phenomenology

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