Determination of the gluon condensate and the four quark condensate via FESR

Bertlmann, Reinhold A.; Domínguez, C. A.; Loewe, M.; Perrottet, M.; Rafael, Eduardo de

doi:10.1007/bf01550999

Cited by 163 publications

(91 citation statements)

References 49 publications

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“…This simple parametrization of the lattice data can be improved using a smooth function without changing the conclusions to be reached with Eq.(17). At T=0 the gluon condensate has been extracted from data on e + e − annihilation, and τ -lepton hadronic decays [13]: αs π G 2 = (0.05 ± 0.02)GeV 4 . We do not consider a gluonic twist-two term in the OPE [14] as it is negligible, as in the case of vector (J/ψ) charmonium [7].…”

Section: Qcd Sum Rulesmentioning

confidence: 99%

(Pseudo)scalar charmonium in finite temperature QCD

et al. 2011

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The hadronic parameters of pseudoscalar (η c ) and scalar (χ c ) charmonium are determined at finite temperature from Hilbert moment QCD sum rules. These parameters are the hadron mass, leptonic decay constant, total width, and continuum threshold (s 0 ). Results for s 0 (T ) in both channels indicate that s 0 (T ) starts approximately constant, and then it decreases monotonically with increasing T until it reaches the QCD threshold, s th = 4m 2 Q , at a critical temperature T = T c ≃ 180 MeV interpreted as the deconfinement temperature. The other hadronic parameters behave qualitatively similarly to those of the J/ψ, as determined in this same framework. The hadron mass is essentially constant, the total width is initially independent of T, and after T /T c ≃ 0.80 it begins to increase with increasing T up to T /T c ≃ 0.90 (0.95) for χ c (η c ), and subsequently it decreases sharply up to T ≃ 0.94 (0.99) T c , for χ c (η c ), beyond which the sum rules are no longer valid. The decay constant of χ c at first remains basically flat up to T ≃ 0.80 T c , then it starts to decrease up to T ≃ 0.90 T c , and finally it increases sharply with increasing T . In the case of η c the decay constant does not change up to T ≃ 0.80 T c where it begins a gentle increase up to T ≃ 0.95 T c beyond which it increases dramatically with increasing T . This behaviour contrasts with that of light-light and heavy-light quark systems, and it suggests the survival of the η c and the χ c states beyond the critical temperature, as already found for the J/ψ from similar QCD sum rules. These conclusions are very stable against changes in the critical temperature in the wide range T c = 180 − 260 MeV.

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Section: Qcd Sum Rulesmentioning

confidence: 99%

(Pseudo)scalar charmonium in finite temperature QCD

et al. 2011

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“…For instance, the R τ -ratio provides the cleanest determination of the running strong coupling at the scale of the τ -mass. In addition, these data have been used in the past to extract the values of some of the QCD vacuum condensates entering the operator product expansion (OPE) of current correlators at short distances beyond perturbation theory [6][7][8][9][10][11][12][13][14][15][16][17]. This OPE is one of the two fundamental pillars of the method of QCD sum rules, the other being the assumption of quark-hadron duality [18].…”

Section: Introductionmentioning

confidence: 99%

Chiral sum rules and vacuum condensates from tau-lepton decay data

Domínguez¹,

Hernández²,

Schilcher³

et al. 2015

J. High Energ. Phys.

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QCD finite energy sum rules, together with the latest updated ALEPH data on hadronic decays of the tau-lepton are used in order to determine the vacuum condensates of dimension d = 2 and d = 4. These data are also used to check the validity of the Weinberg sum rules, and to determine the chiral condensates of dimension d = 6 and d = 8, as well as the chiral correlator at zero momentum, proportional to the counter term of the O(p 4 ) Lagrangian of chiral perturbation theory,L 10 . Suitable (pinched) integration kernels are introduced in the sum rules in order to suppress potential quark-hadron duality violations. We find no compelling indications of duality violations in the kinematic region above s ≃ 2.2 GeV 2 after using pinched integration kernels.

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“…One still seems to have at least a connection between chiral restoration -drop of two-and fourquark condensates -and in-medium changes, no matter whether it is a mass shift or a broadening or a more complicated in-medium modification [13,34]. However, also point 2 and as its consequence point 4 are questionable: Whether the four-quark condensates factorize at least in vacuum is discussed since the invention of QCD sum rules, see, e.g., [23,24,[35][36][37][38][39][40][41] and for in-medium situations also [27,[42][43][44][45][46]. Raising doubts on point 2 immediately questions point 4 and in that way the seemingly clear connection between chiral restoration and in-medium changes gets lost.…”

Section: Introductionmentioning

confidence: 99%

The impact of chirally odd condensates on the rho meson

et al. 2012

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Based on QCD sum rules we explore the consequences of a pure chiral restoration scenario for the ρ meson, where all chiral symmetry breaking condensates are dropped whereas the chirally symmetric condensates remain at their vacuum values. This pure chiral restoration scenario causes the drop of the ρ spectral moment by about 120 MeV. The complementarity of mass shift and broadening is discussed. A simple parametrization of the ρ spectral function leads to a width of about 600 MeV if no shift of the peak position is assumed.

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Determination of the gluon condensate and the four quark condensate via FESR

Cited by 163 publications

References 49 publications

(Pseudo)scalar charmonium in finite temperature QCD

(Pseudo)scalar charmonium in finite temperature QCD

Chiral sum rules and vacuum condensates from tau-lepton decay data

The impact of chirally odd condensates on the rho meson

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