Quark masses and strong coupling constant in 2+1 flavor QCD
  We present a determination of the strange, charm and bottom quark masses as well as the strong coupling constant in 2+1 flavor lattice QCD simulations using highly improved staggered quark action. The ratios of the charm quark mass to the strange quark mass and the bottom quark mass to the charm quark mass are obtained from the meson masses calculated on the lattice and found to be $m_c/m_s=11.871(91)$ and $m_b/m_c=4.528(57)$ in the continuum limit. We also determine the strong coupling constant and the charm quark mass using the moments of pseudoscalar charmonium correlators: $\alpha_s(\mu=m_c)=0.3697(85)$ and $m_c(\mu=m_c)=1.267(12)$ GeV. Our result for $\alpha_s$ corresponds to the determination of the strong coupling constant at the lowest energy scale so far and is translated to the value $\alpha_s(\mu=M_Z,n_f=5)=0.11622(84)$. 
Y. Maezawa and P. Petreczky
hep-lat hep-ph