Statistical production of Bc mesons in heavy-ion collisions at the LHC energy

Abstract

The recombination production of $B_c$ mesons in heavy-ion collisions at the LHC energy is facilitated by the abundant and highly thermalized charm (c) quarks transported in the deconfined medium created. We study the production of $B_c$ mesons via c and bottom (b) quark recombination in a statistical fashion by placing $B_c$ in the position of a member of the family of open b hadrons, which allows us to make quantitative predictions for the modifications of the production fraction ($f_c$) of $B_c$ mesons and its relative production to B mesons in $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV Pb-Pb collisions with respect to proton-proton (pp) collisions at the same energy. The statistical production yield of $B_c$ mesons is converted into the transverse momentum ($p_T$) distribution with the shape computed from resonance recombination using the c- and b-quark phase space distributions that have been simulated via Langevin diffusion and constrained by open c- and b-hadron observables. Supplemented with the component fragmented from b-quark spectrum that dominates at high $p_T$, the total $p_T$ spectrum of $B_c$ mesons is obtained and converted into the $p_T$ dependent nuclear modification factor ($R_{\mathrm{AA}}$). Both $f_c$ and the integrated $R_{\mathrm{AA}}$ exhibit a ∼5-fold enhancement in central Pb-Pb collisions relative to the pp reference. Comparison with data measured by the CMS experiment shows decent agreement within theoretical and experimental uncertainties.