Measurement of Bc(2S)+ and Bc*(2S)+ cross section ratios in proton-proton collisions at s=13 TeV

The ratios of the B_c(2S)⁺ to B⁺_c, B∗_c(2S)⁺ to B⁺_c, and B∗_c(2S)⁺ to B_c(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 B⁺_c meson phase space region defined by the transverse momentum p_T > 15  GeV and absolute rapidity |y| < 2.4, with the excited B^((*))_c(2S)⁺ states reconstructed through the B^((*))_c⁺π⁺π⁻, followed by the B⁺_c → J/ψπ⁺ and J/ψ → μ⁺μ⁻ decays. The B_c(2S)⁺ to B⁺c, B∗_c(2S)⁺ to B⁺_c, and B∗_c(2S)⁺ to B_c(2S)⁺ cross section ratios, including the unknown B^((*))_c(2S)⁺ → B^((*))_c⁺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 p_T or |y| of the B⁺_c meson. The normalized dipion invariant mass distributions from the decays B^((*))_c(2S)⁺ → B^((*))_c⁺π⁺π⁻ are also reported.