Search for excited Bc + states

Abstract

: A search is performed in the invariant mass spectrum of the B+ c π +π − system for the excited B+ c states Bc(21S0) + and Bc(23S1) + using a data sample of pp collisions collected by the LHCb experiment at the centre-of-mass energy of √ s = 8 TeV, corresponding to an integrated luminosity of 2 fb−1 . No evidence is seen for either state. Upper limits on the ratios of the production cross-sections of the Bc(21S0) + and Bc(23S1) + states times the branching fractions of Bc(21S0) + → B+ c π +π − and Bc(23S1) + → B∗+ c π +π − over the production cross-section of the B+ c state are given as a function of their masses. They are found to be between 0.02 and 0.14 at 95% confidence level for Bc(21S0) + and Bc(23S1) + in the mass ranges [6830, 6890] MeV/c2 and [6795, 6890] MeV/c2 , respectively.