Measurement of B$_\mathrm{c}$(2S)$^+$ and B$_\mathrm{c}^*$(2S)$^+$ cross section ratios in proton-proton collisions at $\sqrt{s} =$ 13 TeV
The ratios of the Bc(2S)+ to Bc+, Bc*(2S)+ to Bc+, and Bc*(2S)+ to Bc(2S)+ production cross sections are measured in proton-proton collisions at s=13 TeV, using a data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 143 fb-1. The three measurements are made in the Bc+ meson phase space region defined by the transverse momentum pT>15 GeV and absolute rapidity |y|<2.4, with the excited Bc(*)(2S)+ states reconstructed through the Bc(*)+π+π−, followed by the Bc+→J/ψπ+ and J/ψ→μ+μ− decays. The Bc(2S)+ to Bc+, Bc*(2S)+ to Bc+, and Bc*(2S)+ to Bc(2S)+ cross section ratios, including the unknown Bc(*)(2S)+→Bc(*)+π+π− branching fractions, are (3.47±0.63(stat)±0.33(syst))%, (4.69±0.71(stat)±0.56(syst))%, and 1.35±0.32(stat)±0.09(syst), respectively. None of these ratios shows a significant dependence on the pT or |y| of the Bc+ meson. The normalized dipion invariant mass distributions from the decays Bc(*)(2S)+→Bc(*)+π+π− are also reported.