2-loop Quarkonium Hamiltonian (Non-annihilation Channel)

Heavy quarkonium system provides an ideal laboratory to investigate QCD deeply. We report on our calculation of the two-loop quarkonium Hamiltonian (in the non-annihilation channel). This is the first non-trivial calculation of the $\rm N^4LO$ corrections to the quarkonium Hamiltonian, defined in the potential-NRQCD effective field theory. We explain the procedure of this computation as well as theoretically interesting points, and then we present the result.