The prompt production of the charmonium χ c1 and χ c2 mesons has been studied in proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of s=7 TeV. The χ c mesons are identified through their decays χ c→J/ψγ with J/ψ→μ +μ - using 36 pb -1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for the two χ c spin states, σ(χ c2)/σ(χ c1), has been determined as a function of the J/ψ transverse momentum, pTJ/ψ, in the range from 2 to 15 GeV/c. The results are in agreement with the next-to-leading order non-relativistic QCD model at high pTJ/ψ and lie consistently above the pure leading-order colour-singlet prediction.
|Number of pages||9|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 14 Aug 2012|
Bibliographical noteFunding Information:
We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at CERN and at the LHCb institutes, and acknowledge support from the National Agencies: CAPES , CNPq , FAPERJ and FINEP (Brazil); CERN ; NSFC (China); CNRS/IN2P3 (France); BMBF , DFG , HGF and MPG (Germany); SFI (Ireland); INFN (Italy); FOM and NWO (The Netherlands); SCSR (Poland); ANCS (Romania); MinES of Russia and Rosatom (Russia); MICINN , XuntaGal and GENCAT (Spain); SNSF and SER (Switzerland); NAS Ukraine (Ukraine); STFC (United Kingdom); NSF (USA). We also acknowledge the support received from the ERC under FP7 and the Region Auvergne .
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All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics