Measurement of the χ b (3P) mass and of the relative rate of χ b1(1P) and χ b2(1P) production

Abstract

The production of b mesons in proton-proton collisions is studied using a data sample collected by the LHCb detector, at centre-of-mass energies of p s = 7 and 8TeV and corresponding to an integrated luminosity of 3.0 fb−1. The b mesons are identified through their decays to (1S) and (2S) using photons that converted to e+e− pairs in the detector. The relative prompt production rate of b1(1P) and b2(1P) mesons is measured as a function of the (1S) transverse momentum in the b rapidity range 2.0 < y < 4.5. A precise measurement of the b(3P) mass is also performed. Assuming a mass splitting between the b1(3P) and the b2(3P) states of 10.5 MeV/c2, the measured mass of the b1(3P) meson is m( b1(3P)) = 10515.7+2.2 −3.9(stat)+1.5 −2.1(syst)MeV/c2.