Gauge-invariant screening masses and static quark free energies in Nf=2+1 QCD at nonzero baryon density

Abstract

We discuss the extension of gauge-invariant electric and magnetic screening masses in the quark-gluon plasma to the case of a finite baryon density, defining them in terms of a matrix of Polyakov loop correlators. We present lattice results for N f ¼ 2 þ 1 QCD with physical quark masses, obtained using the imaginary chemical potential approach, which indicate that the screening masses increase as a function of μ B . A separate analysis is carried out for the theoretically interesting case μ B =T ¼ 3iπ, where charge conjugation is not explicitly broken and the usual definition of the screening masses can be used for temperatures below the Roberge-Weiss transition. Finally, we investigate the dependence of the static quark free energy on the baryon chemical potential, showing that it is a decreasing function of μ B , which displays a peculiar behavior as the pseudocritical transition temperature at μ B ¼ 0 is approached.

Color screening in ( 2+1 )-flavor QCD

“…To validate the pNRQCD framework on a quantitative level we reconstruct the subtracted free energy of a static Q Q pair using the pNRQCD decomposition formula (27) and lattice results for the zero temperature static Q Q energy V S , taken from Refs. [58,68], as a proxy for V s , and for the Polyakov loop expectation value in the fundamental representation, L F ≡ L, taken from Ref.…”

“…[26] results in the continuum limit have been presented. Very recently the Polyakov loop correlators have been calculated at nonzero baryon density [27].…”

Heavy Quarkonium in Extreme Conditions

“…There are efforts ongoing in the lattice community to extend the computation of screening masses to a medium with finite Baryo-chemical potential , via the Taylor expansion method [144] or analytic continuation from imaginary chemical potential [150,151]. In the latter case charge conjugation symmetry is broken explicitly and the standard prescription discussed here to separate color electric and magnetic contributions is inapplicable.…”

Color Screening in Quantum Chromodynamics

“…Hence, mixing between the bound states with even or odd numbers of electric A 0 gluons may eventually become quite strong in the medium at finite density, which implies that the real or imaginary parts of the Polyakov loop cannot fluctuate independently. Yet the mass m(0 + + ) of the lightest scalar state has been found to be still significantly smaller than the masses of all other states in dimensionally-reduced QCD lattice simula- The screening masses m 1 /T and m 2 /T associated with the diagonalized components of the correlation matrix of the real and imaginary parts of the Polyakov loop at imaginary chemical potential [93]. Available results are obtained with N τ = 8. tions [26] with an increase of only about 10% at µ/T = 1 and about 20% at µ/T = 2.…”