Measurement of the $χ_b(3P)$ mass and of the relative rate of $χ_{b1}(1P)$ and $χ_{b2}(1P)$ production
hep-ex
/ Authors
LHCb collaboration, R. Aaij, B. Adeva, M. Adinolfi, A. Affolder, Z. Ajaltouni, S. Akar, J. Albrecht, F. Alessio, M. Alexander
and 690 more authors
S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, S. Amerio, Y. Amhis, L. An, L. Anderlini, J. Anderson, R. Andreassen, M. Andreotti, J. E. Andrews, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, M. Baalouch, S. Bachmann, J. J. Back, A. Badalov
/ Abstract
The production of $χ_b$ mesons in proton-proton collisions is studied using a data sample collected by the LHCb detector, at centre-of-mass energies of $\sqrt{s}=7$ and $8$ TeV and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $χ_b$ mesons are identified through their decays to $Υ(1S)γ$ and $Υ(2S)γ$ using photons that converted to $e^+e^-$ pairs in the detector. The relative prompt production rate of $χ_{b1}(1P)$ and $χ_{b2}(1P)$ mesons is measured as a function of the $Υ(1S)$ transverse momentum in the $χ_b$ rapidity range $2.0<y<4.5$. A precise measurement of the $χ_b(3P)$ mass is also performed. Assuming a mass splitting between the $χ_{b1}(3P)$ and the $χ_{b2}(3P)$ states of 10.5 MeV/$c^2$, the measured mass of the $χ_{b1}(3P)$ meson is $ m(χ_{b1}(3P))= 10515.7^{+2.2}_{-3.9}(stat) ^{+1.5}_{-2.1}(syst) MeV/c^2.$