Chiral phase transition of QCD with $N_f=2+1$ flavors from holography
  Chiral phase transition for three-flavor $N_f=2+1$ QCD with $m_u=m_d\neq m_s$ is investigated in a modified soft-wall holographic QCD model. Solving temperature dependent chiral condensates from equations of motion of the modified soft-wall model, we extract the quark mass dependence of the order of chiral phase transition in the case of $N_f=2+1$, and the result is in agreement with the "Colombia Plot", which is summarized from lattice simulations and other non-perturbative methods. First order phase transition is observed around the three flavor chiral limit $m_{u/d}=0, m_{s}=0$, while at sufficient large quark masses it turns to be a crossover phase transition. The first order and crossover regions are separated by a second order phase transition line. The second order line is divided into two parts by the $m_{u/d}=m_s$ line, and the $m_s$ dependence of the transition temperature in these two parts are totally contrast, which might indicate that the two parts are governed by different universality classes. 
Danning Li and Mei Huang
hep-ph