Gauge dependence and matching procedure of a nonrelativistic QCD   boundstate formalism
  We investigate gauge dependence of a nonrelativistic boundstate formalism used in contemporary calculations. It is known that the effective Hamiltonian of the boundstate system depends on the choice of gauge. We obtain the gauge transformation charge of the Hamiltonian, by which gauge independence of the mass spectrum and gauge dependences of the boundstate wave functions are dictated. We raise two questions of practical and physical interest, and provide answers to them. 
Y. Sumino