On the critical line of 2+1 flavor QCD

Understand

We determine the curvature of the (pseudo)critical line of QCD with $n_f$=2+1 staggered fermions at nonzero temperature and quark density, by analytic continuation from imaginary chemical potentials.

• Monte Carlo simulations are performed adopting the HISQ/tree action discretization, as implemented in the code by the MILC collaboration, suitably modified to include a nonzero imaginary baryon chemical potential.
• We work on a line of constant physics, as determined in Ref.\cite{Bazavov:2011nk}, adjusting the couplings so as to keep the strange quark mass $m_s$ fixed at its physical value, with a light to strange mass ratio $m_l/m_s=1/20$.
• In the present investigation we set the chemical potential at the same value for the three quark species, $\mu_l=\mu_s\equiv \mu$.