Ultrasoft effects in heavy-quarkonium physics

Bernd A. Kniehl, Alexander A. Penin
1999 Nuclear Physics B  
In the framework of nonrelativistic QCD, we consider a new class of radiative corrections, which are generated at next-to-next-to-next-to-leading order through the chromoelectric dipole interaction of heavy quarkonium with ultrasoft virtual gluons. We provide analytical formulae from which the resulting shifts in the quarkonium energy levels and the wave functions at the origin may be calculated. We discuss the phenomenological implications for the top-antitop and Upsilon systems and point out
more » ... tems and point out some limitations of describing charmonium using a Coulomb potential.
doi:10.1016/s0550-3213(99)00564-7 fatcat:7gk3vxbyevcmhdjg3dfelkgpfa