Applying constrained simulations for low temperature lattice QCD at finite baryon chemical potential

TL;DR

This paper investigates the phase diagram of low temperature QCD at finite baryon chemical potential using density of states and reweighting methods, comparing results and analyzing onset of quark density.

Contribution

It applies the density of states method with pion condensate and gauge action density fixing to low temperature lattice QCD at finite chemical potential, comparing with reweighting.

Findings

Density of states performs similarly to reweighting.

Indication of quark density onset at $bc/m_N \u2248 0.16-0.18$ at $T \u2248 100$ MeV.

Results obtained on lattices with varying sizes and parameters.

Abstract

We study the density of states method as well as reweighting to explore the low temperature phase diagram of QCD at finite baryon chemical potential. We use four flavors of staggered quarks, a tree-level Symanzik improved gauge action and four stout smearing steps on lattices with $N_s=4,6,8$ and $N_t=6 - 16$. We compare our results to that of the phase quenched ensemble and also determine the pion and nucleon masses. In the density of states approach we applied pion condensate or gauge action density fixing. We found that the density of states method performs similarly to reweighting. At $T \approx 100$ MeV, we found an indication of the onset of the quark number density at around $\mu/m_N \sim 0.16 - 0.18$ on $6^4$ lattices at $\beta=2.9$.