Evaluation of QCD sum rules for light vector mesons at finite density and temperature

Zschocke, Sven; Pavlenko, O. P.; Kämpfer, B.

doi:10.1140/epja/i2002-10062-4

Cited by 78 publications

(118 citation statements)

References 23 publications

(50 reference statements)

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“…[16]), causing the small ρ − ω mass splitting in vacuum [17]. Keeping in mind the important role of the 4-quark condensate [27,28] for the in-medium modifications of the vector mesons, we employ the following parameterization (qγ µ γ 5 λ a q) 2 n = 16 9 qq 2 0κ 0 1 +κ…”

Section: Qcd Sum Rulementioning

confidence: 99%

“…Therefore, we use in the present work one parameter κ N , keeping in mind that it may slightly differ for different light vector mesons.) Using the above condensates and usual Wilson coefficients one gets as relevant terms for mass dimension ≤ 6 and twist ≤ 2 [27,28] …”

Section: Qcd Sum Rulementioning

confidence: 99%

“…The case of finite baryon density and temperature has been considered in [27]. Here we focus on density effects with the reasoning that temperature effects below 100 MeV are negligible.…”

Section: Qcd Sum Rulementioning

confidence: 99%

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Finite-width QCD sum rules for ρ and ω mesons

Kämpfer

Zschocke

2004

Progress in Particle and Nuclear Physics

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We present a combined analysis of the in-medium behavior of ρ and ω mesons within the Borel QCD sum rule taking into account finite widths. IntroductionThe experiments at the High-Acceptance Di-Electron Spectrometer HADES [1] are aimed at verifying predictions of the behavior of light vector mesons in nuclear matter. Due to the decay channel V → e + e − a measurement of the escaping di-electrons can reveal directly the properties of the parent mesons, V = ρ, ω, · · ·, since the interaction probability of the e ± with the ambient strongly interacting medium is small.In relativistic heavy-ion collisions temperature effects play an important role, which also cause a change of the properties of vector mesons. Indeed, the experiments of the CERES collaboration at the CERN-SPS [2] can only be explained by assuming strong medium effects, in particular for the ρ meson (cf. [3,4] and further references therein). This seems to be confirmed at higher beam energies, as delivered by the Relativistic Heavy Ion Collider, since the ρ meson, as measured via the π + π − decay channel, suffers some modification [5]. In contrast, in heavy-ion collisions at typical SIS18 energies, i.e., at beam energies around 1 AGeV, the in-medium behavior of vector mesons in compressed nuclear matter can be studied, where temperature effects are small and may be neglected. Complementary to heavy-ion collisions one can seek for in-medium modifications in reactions of hadronic projectiles [6] or real and virtual photons [7] at nuclei, as already at nuclear saturation density sizeable modifications of vector mesons are predicted.There exists a vastly extended literature on the in-medium modification of hadrons. We mention here only the Brown-Rho scaling hypothesis, according to which a mass shift of a vector meson is directly interrelated to a change of the chiral condensate [8], and the vector manifestation [9], the effective Lagrangian approach [10], purely hadronic approaches [11,12], and QCD sum rules [13,14,15,16]. QCD sum rules [17] follow the idea of duality (cf. [18]) by relating quantities expressed by partonic (quark and gluon) degrees of freedom with hadronic observables. We take here the attitude to assume that the partonic quantities are given and examine the QCD sum rule to elucidate the in-medium change of the ρ and ω meson on a common footing. The corresponding current operators, expressed by the interpolating quark field operators u and d have the form J ρ µ = 1 2 (ūγ µ u−dγ µ d) and J ω µ = 1 2 (ūγ µ u+dγ µ d), * Dedicated to the memory of O.P. Pavlenko

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Section: Qcd Sum Rulementioning

confidence: 99%

Section: Qcd Sum Rulementioning

confidence: 99%

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Finite-width QCD sum rules for ρ and ω mesons

Kämpfer

Zschocke

2004

Progress in Particle and Nuclear Physics

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“…As is well known for the ρ meson [15,16,17], the QCDSR cannot uniquely predict the in-medium properties of the spectral function, but it can provide constraints on model calculations. Weinberg sum rules (WSRs) relate chiral order parameters to energy moments of the difference between the vector and axialvector spectral functions [18],…”

Section: Qcd and Weinberg Sum Rulesmentioning

confidence: 99%

Dileptons and Chiral Symmetry Restoration

Hohler

Rapp

2016

Nuclear and Particle Physics Proceedings

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We report on recent work relating the medium effects observed in dilepton spectra in heavy-ion collisions to potential signals of chiral symmetry restoration. The key connection remains the approach to spectral function degeneracy between the vector-isovector channel with its chiral partner, the axialvector-isovector channel. Several approaches are discussed to elaborate this connection, namely QCD and Weinberg sum rules with input for chiral order parameters from lattice QCD, and chiral hadronic theory to directly evaluate the medium effects of the axialvector channel and the pertinent pion decay constant as function of temperature. A pattern emerges where the chiral mass splitting between ρ and a 1 burns off and is accompanied by a strong broadening of the spectral distributions.

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“…All these quantities have been intensively studied in the context of heavy ion collisions. The spectral function has therefore naturally been investigated within many approaches, such as perturbative QCD [2], the AdS/CFT correspondence [3], model calculations [4], low-energy effective theory based on hadronic degrees of freedom [5,6], sum rules [7][8][9][10], and lattice QCD [11][12][13][14][15][16][17][18][19], which have led to a large number of diverse results. Under such circumstances, it is useful to have exact constraints on the spectral function that all approaches should satisfy.…”

Section: Introductionmentioning

confidence: 99%

Exact sum rules for vector channel at finite temperature and their application to lattice QCD analysis

Satow

Gubler

2017

EPJ Web Conf.

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Abstract. We derive three exact sum rules for the spectral function of the electromagnetic current with zero spatial momentum at finite temperature. Possible applications of the three sum rules to lattice computations of the spectral function and transport coefficients are also discussed: We propose an ansatz for the spectral function that can be applied to all three sum rules and fit it to available lattice data of the Euclidean vector correlator above the critical temperature. As a result, we obtain estimates for both the electrical conductivity σ and the second order transport coefficient τ J .

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Evaluation of QCD sum rules for light vector mesons at finite density and temperature

Cited by 78 publications

References 23 publications

Finite-width QCD sum rules for ρ and ω mesons

Finite-width QCD sum rules for ρ and ω mesons

Dileptons and Chiral Symmetry Restoration

Exact sum rules for vector channel at finite temperature and their application to lattice QCD analysis

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