(Pseudo)scalar charmonium in finite temperature QCD

Abstract

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c ), and subsequently it decreases sharply up to T ≃ 0.94 (0.99) T c , for χ c (η c ), beyond which the sum rules are no longer valid.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.

Quarkonium at finite temperature: towards realistic phenomenology from first principles

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QCD determination of the magnetic field dependence of QCD and hadronic parameters

“…It should be mentioned that recently an intriguing connection has been found between s 0 ðTÞ and the Polyakov loop, the deconfining object of LQCD [6]. For heavy-heavy quark systems it was first found using QCD sum rules that these states survive the critical temperature for deconfinement [7]. This unexpected situation was later confirmed by LQCD determinations [8].…”

Power corrections to the electromagnetic spectral function and the dilepton rate in QCD plasma within operator product expansion in D = 4

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