Measurement of the production cross section ratio σ(χb2(1P))/σ(χb1(1P)) in pp collisions at √s = 8 TeV

CMS Collaboration

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A measurement of the production cross section ratio σ(χb2(1P))/σ(χb1(1P)) is presented. The χb1(1P) and χb2(1P) bottomonium states, promptly produced in pp collisions at √s = 8 TeV, are detected by the CMS experiment at the CERN LHC through their radiative decays χb1,2(1P) → ϒ(1S) + γ. The emitted photons are measured through their conversion to e+e pairs, whose reconstruction allows the two states to be resolved. The ϒ(1S) is measured through its decay to two muons. An event sample corresponding to an integrated luminosity of 20.7fb−1 is used to measure the cross section ratio in a phase-space region defined by the photon pseudorapidity, |ηγ| < 1.0; the ϒ(1S) rapidity, |yϒ| < 1.5; and the ϒ(1S) transverse momentum, 7 < pϒT < 40 GeV. The cross section ratio shows no significant dependence on the ϒ(1S) transverse momentum, with a measured average value of 0.85 ±0.07 (stat+syst) ±0.08 (BF), where the first uncertainty is the combination of the experimental statistical and systematic uncertainties and the second is from the uncertainty in the ratio of the χb branching fractions.
Original languageEnglish
Pages (from-to)383-402
Number of pages20
JournalPhysics Letters B
Publication statusPublished - 2015
Externally publishedYes


  • CMS
  • Quarkonium production
  • P-wave states
  • Bottomonium

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