LHCb CollaborationAaij, R.Abellan Beteta, C.Adeva, B.Adinolfi, M.Adrover, C.Affolder, A.Ajaltouni, Z.Albrecht, J.Alessio, F.Alexander, M.Ali, S.Alkhazov, G.Alvarez Cartelle, P.Amato, S.Amhis, Y.Anderson, J.Appleby, R. B.Gutierrez, O. AquinesArchilli, F.Arrabito, L.Artamonov, A.Artuso, M.Aslanides, E.Auriemma, G.Bachmann, S.Back, J. J.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.Bifani, S.Bird, T.Bizzeti, A.Bjornstad, P. M.Blake, T.Blanc, F.Blanks, C.Blouw, J.Blusk, S.Bobrov, A.Bocci, V.Bondar, A.Bondar, N.Bonivento, W.Borghi, S.Borgia, A.Bowcock, T. J. V.Bozzi, C.Brambach, T.Van Den Brand, J.Bressieux, J.Brett, D.Britsch, M.Britton, T.Brook, N. H.Brown, H.De Bruyn, K.Buechler-Germann, A.Burducea, I.Bursche, A.Buytaert, J.Cadeddu, S.Callot, O.Calvi, M.Calvo Gomez, M.Camboni, A.Campana, P.Carbone, A.Carboni, G.Cardinale, R.Cardini, A.Carson, L.Carvalho Akiba, K.Casse, G.Cattaneo, M.Cauet, Ch.Charles, M.Charpentier, Ph.Chiapolini, N.Ciba, K.Cid Vidal, X.Ciezarek, G.Clarke, P. E. L.Clemencic, M.Cliff, H. V.Closier, J.Coca, C.Coco, V.Cogan, J.Collins, P.Comerma-Montells, A.Contu, A.Cook, A.Coombes, M.Corti, G.Couturier, B.Cowan, G. A.Currie, R.D'Ambrosio, C.David, P.David, P. N. Y.De Bonis, I.De Capua, S.De Cian, M.De Lorenzi, F.De Miranda, J. M.De Paula, L.De Simone, P.Decamp, D.Deckenhoff, M.Degaudenzi, H.Del Buono, L.Deplano, C.Derkach, D.Deschamps, O.Dettori, F.Dickens, J.Dijkstra, H.Diniz Batista, R.Domingo Bonal, F.Donleavy, S.Dordei, F.Dosil Suarez, A.Dossett, D.Dovbnya, A.Dupertuis, F.Dzhelyadin, R.Dziurda, A.Easo, S.Egede, U.Egorychev, V.Eidelman, S.Van Eijk, D.Eisele, F.Eisenhardt, S.Ekelhof, R.Eklund, L.Elsasser, Ch.Elsby, D.Esperante Pereira, D.Falabella, A.Faerber, C.Fardell, G.Farinelli, C.Farry, S.Fave, V.Fernandez Albor, V.Ferro-Luzzi, M.Filippov, S.Fitzpatrick, C.Fontana, M.Fontanelli, F.Forty, R.Francisco, O.Frank, M.Frei, C.Frosini, M.Furcas, S.Gallas Torreira, A.Galli, D.Gandelman, M.Gandini, P.Gao, Y.Garnier, J. -C.Garofoli, J.Tico, J. GarraGarrido, L.Gascon, D.Gaspar, C.Gauld, R.Gauvin, N.Gersabeck, M.Gershon, T.Ghez, Ph.Gibson, V.Gligorov, V. V.Goebel, C.Golubkov, D.Golutvin, A.Gomes, A.Gordon, H.Grabalosa Gandara, M.Graciani Diaz, R.Cardoso, L. A. 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C.Zhang, Y.Zhelezov, A.Zhong, L.Zvyagin, A.2013-03-282013-03-282013-03-28201210.1016/j.physletb.2012.10.068https://infoscience.epfl.ch/handle/20.500.14299/91130WOS:000312687700017The prompt production of charmonium chi(c) and J/psi states is studied in proton-proton collisions at a centre-of-mass energy of root s = 7 TeV at the Large Hadron Collider. The chi(c) and J/psi mesons are identified through their decays chi(c) -> J/psi gamma and J/psi -> mu(+)mu(-) using 36 pb(-1) of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for chi(c) and J/psi, sigma(chi(c) -> J/psi gamma)/sigma(J/psi). is determined as a function of the J/psi, transverse momentum in the range 2 < P-T(J/psi) < 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 P-T(J/psi) region. (C) 2012 CERN. 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