Measurement of the chib2/chib1 production cross section ratio in pp collisions at sqrt(s)= 8 TeV

Collaboration
2013
12 pages
Report number:
  • CMS-PAS-BPH-13-005
Experiments:

Citations per year

2013201420152016201702468
Abstract:
The ratio of cross sections of χb2(1P)\chi_{\mathrm{b}2}(1\mathrm{P}) and χb1(1P)\chi_{\mathrm{b}1}(1\mathrm{P}) bottomonium states promptly produced in pp collisions at s=8\sqrt{s}= 8\,TeV is measured by detecting their radiative decays χb1,2(1P)Υ(1S)+γ\chi_{\mathrm{b}1,2}(1\mathrm{P}) \rightarrow \Upsilon(1\mathrm{S}) + \gamma with the CMS experiment. The emitted photons are detected through their conversion to e+ee^+e^- pairs, with the electron trajectories accurately reconstructed in the silicon tracker, so that the two states can be resolved with a good mass resolution. The measurement is based on an event sample corresponding to an integrated luminosity of 20.7\,fb1^{-1} and is performed in a phase space region defined by selection cuts on the photon pseudorapidity and on the Υ\Upsilon transverse momentum and rapidity: ηγ<1.0| \eta^\gamma | < 1.0, 7<pTΥ<407 < p_{\rm T}^\Upsilon < 40\,GeV, and yΥ<1.5|y^\Upsilon | < 1.5. The measured cross-section ratio is around 0.9, with no significant dependence on p_{\rm T}^\Y.
Note:
  • Preliminary results
  • Data
  • p p: scattering
  • cross section: ratio: measured
  • bottomonium: direct production
  • chi/b1(9890): radiative decay
  • chi/b2(9915): radiative decay
  • photon: particle identification
  • Upsilon(9460): transverse momentum
  • mass resolution
  • phase space