Hadronic fluctuations and correlations at nonzero chemical potential

TL;DR

This study uses lattice QCD to analyze fluctuations and correlations of conserved charges at nonzero chemical potential, revealing significant increases below the critical temperature and peaks at nonzero density.

Contribution

It provides the first detailed lattice QCD analysis of baryon number and strangeness fluctuations at nonzero density using a Taylor expansion approach.

Findings

Fluctuations and correlations peak at nonzero density.

Below T_c, fluctuations increase drastically.

Above T_c, fluctuations remain relatively unaffected.

Abstract

We present a lattice study of fluctuations and correlations among the conserved charges baryon number and strangeness in (2+1)-flavor QCD. The lattice calculations are based on a Taylor expansion of the pressure. Results are presented at zero and nonzero density on lattices with four and six time slices, corresponding to a lattice spacing of $a\approx 0.25$ fm and $a\approx 0.16$ fm, respectively. The quark masses are almost physical, i.e. the light quark mass has been chosen to one tenth of the physical strange quark mass while the strange quark mass has been set to its physical value. We find that all analyzed fluctuations and correlations develop a peak at nonzero density, when they are treated in an expansion up to sixth order. Especially below the critical temperature ($T_c$) fluctuations and correlations increase drastically, whereas above $T_c$ they are rather unaffected.