Charmonium potential from full lattice QCD

We present both spin-independent and spin-dependent parts of a central interquark potential for charmonium states, which is calculated in 2+1 flavor dynamical lattice QCD using the PACS-CS gauge configurations with a lattice cutoff of a ^-1 2.2GeV. Our simulations are performed with a relativistic heavy-quark action for the charm quark at the lightest pion mass, M _π=156(7)MeV, in a spatial volume of ^(3fm)3. We observe that the spin-independent charmonium potential obtained from lattice QCD with almost physical quark masses is quite similar to the Cornell potential used in nonrelativistic potential models. The spin-spin potential, which is calculated in full lattice QCD for the first time, properly exhibits a finite-range repulsive interaction. Its r-dependence is different from the Fermi-Breit type potential, which is widely adopted in quark potential models.