The prompt production of charmonium χ c and J/ψ states is studied in proton-proton collisions at a centre-of-mass energy of s=7 TeV at the Large Hadron Collider. The χ c and J/ψ mesons are identified through their decays χ c→J/ψγ and 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 χ c and J/ψ, σ(χ c→J/ψγ)/σ(J/ψ), is determined as a function of the J/ψ transverse momentum in the range 2<pTJ/ψ<15 GeV/c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low pTJ/ψ region.
|Number of pages||10|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 5 Dec 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 .
Copyright 2012 Elsevier B.V., All rights reserved.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics