Measurement of B c ( 2 S ) + and B ∗ c ( 2 S ) + cross section ratios in proton-proton collisions at √ s = 13 TeV

Abstract

The ratios of the B c ( 2 S ) + to B + c , B ∗ c ( 2 S ) + to B + c , and B ∗ c ( 2 S ) + to B c ( 2 S ) + 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 ( 2 S ) + states reconstructed through the B ( * ) + c π + π − , followed by the B + c → J / ψ π + and J / ψ → μ + μ − decays. The B c ( 2 S ) + to B + c , B ∗ c ( 2 S ) + to B + c , and B ∗ c ( 2 S ) + to B c ( 2 S ) + cross section ratios, including the unknown B ( * ) c ( 2 S ) + → 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 ( 2 S ) + → B ( * ) + c π + π − are also reported.