Exploring phase diagram of $N_f=3$ QCD at $\mu=0$ with HISQ fermions

We studied the QCD phase transition as a function of quark mass in the $N_f=3$ QCD at vanishing baryon density. Lattice simulations have been performed using Highly Improved Staggered Quarks on $N_{\tau}=6$ lattices with quark masses that correspond to pion masses in the region $80 \lesssim m_{\pi} \lesssim 230 $MeV. We found no evidence of the first order phase transition in the current pion mass window. The pion mass at the critical point where the first order phase transition starts is estimated to be $m^c_{\pi}\lesssim 45$ MeV.