Measurement of the cross-section ratio for prompt production at

• Published in: Physics letters. B 2012-08, Vol.714 (2-5), p.215-223
• Main Authors: Aaij, R, Abellan Beteta, C, Adeva, B, Adinolfi, M, Adrover, C, Affolder, A, Ajaltouni, Z, Albrecht, J, Alessio, F, Alexander, M, Alkhazov, G, Alvarez Cartelle, P, Alves, A A, Amato, S, Amhis, Y, Anderson, J, Appleby, R B, Aquines Gutierrez, O, Archilli, F, Arrabito, L, Artamonov, A, Artuso, M, Aslanides, E, Auriemma, G, Bachmann, S, Back, J J, Bailey, D S, Balagura, V, Baldini, W, Barlow, R J, Barschel, C, Barsuk, S, Barter, W, Bates, A, Bauer, C, Bauer, Th, Bay, A, Bediaga, I, Belogurov, S, Belous, K, Belyaev, I, Ben-Haim, E, Benayoun, M, Bencivenni, G, Benson, S, Benton, J, Bernet, R, Bettler, M-O, van Beuzekom, M, Bien, A
• Format: Article
• Language: English
• Subjects: Cross sections; Cross sections (physics); Decay; Elementary particles; Energy (nuclear); Hadrons; Mathematical models; Mesons
• ISSN: 0370-2693
• DOI: 10.1016/j.physletb.2012.06.077

The prompt production of the charmonium I c 1 and I c 2 mesons has been studied in proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of s = 7 TeV . The I c mesons are identified through their decays I c a J / I [gamma] with J / I a mu + mu a using 36 pb a 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for the two I c spin states, I ( I c 2 ) / I ( I c 1 ) , has been determined as a function of the J / I transverse momentum, p T J / I , 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 p T J / I and lie consistently above the pure leading-order colour-singlet prediction.