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

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 Ns=4, 6, 8 and Nt=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 apply pion condensate or gauge action density fixing. We find that the density of states method performs similarly to reweighting. At T≈100 MeV, we find an indication of the onset of the quark number density at around μ/mN∼0.16-0.18 on 64 lattices at β=2.9.