Speaker
Summary
Recently, significant excesses of J/$\psi$ yield at very low transverse momentum ($p_{T} < 0.3$ GeV/c) were observed by the ALICE and STAR experiment, which points to evidence of coherent photon products in hadronic heavy-ion collisions (HHICs). Besides, the previous study [PRC 89(2014)025201] shows that the photon-nucleus contribution is increasingly important for heavy quarkonia as the $\Upsilon$ states. Assuming coherent photoproduction is the underlying mechanism for the J/$\psi$ excess, the coherently produced upsilon from photoproduction in HHICs cannot be neglected either.
In this talk, I will present the model calculations for $\Upsilon$(1S) yields in Pb+Pb collisions at the LHC energies considering the coherent, incoherent and hadronic production, and compare the theoretical results with recent measurements from the CMS Collaboration on $\Upsilon$(1S) production at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV and 5.02 TeV. Besides, predictions for the next LHC run at 5.5 TeV will also be shown.
