The exclusive photoproduction of $Upsilon (nS)$ states were calculated in ultra-peripheral collisions for coherent and incoherent process in PbPb at $sqrt{s_{NN}}$= 5.5 TeV. Different dipole models were compared in the theoretical framework of light-cone color dipole formalism. Moreover, it was calculated the differential cross section for the Upsilon states and their total cross section for two intervals of rapidity: $|y|leq 4$ 4 and $ 2 le$ y $le 4.5$. A systematic study is done on the theoretical uncertainties associated to the production and predictions are presented for the first time for the incoherent cross section of the radially excited states.
تحميل البحث