Quarkonium suppression by energy loss in QCD media.
We calculate the energy loss of heavy quarkonia in finite-temperature QCD media and investigate the effects on quarkonium suppression. Based on the effective vertex derived from the Bethe-Salpeter amplitude for quarkonium dissociation, the collisional and radiative energy loss are obtained by quarkonium-gluon elastic scattering and the associated gluon-bremsstrahlung, respectively. In the energy regime $E < m_{\Upsilon}^2 /T$, the collisional energy loss is dominant over the radiative one and increases with the quarkonium energy and medium temperature. Applying our formalism to the transverse momentum spectra of the $\Upsilon$(1S) in a heavy-ion collision, we find that the energy loss effects during evolution are insignificant compared with the previous estimates of quarkonium dissociation in an expanding plasma. On the other hand, the energy loss effects on the $\Upsilon$(1S) $R_{pPb}$ are found to be comparable with the recent CMS data assuming the quarkonium traverses a static medium with an effective temperature $T\sim 300$ MeV, which can be interpreted as an average effect coming from the gluons inside the nucleons.