Measurement of the relative prompt production rate of χ c2 and χ c1 in pp collisions at $\sqrt{s} = 7\ \mathrm{TeV}

• Published in: The European physical journal. C, Particles and fields Vol. 72; no. 12
• Main Authors: Chatrchyan, S., Khachatryan, V., Sirunyan, A. M., Tumasyan, A., Adam, W., Aguilo, E., Bergauer, T., Dragicevic, M., Erö, J., Fabjan, C., Friedl, M., Frühwirth, R., Ghete, V. M., Hammer, J., Hörmann, N., Hrubec, J., Jeitler, M., Kiesenhofer, W., Knünz, V., Krammer, M., Krätschmer, I., Liko, D., Mikulec, I., Pernicka, M., Rahbaran, B., Rohringer, C., Rohringer, H., Schöfbeck, R., Strauss, J., Taurok, A., Waltenberger, W., Walzel, G., Widl, E., Wulz, C.-E., Mossolov, V., Shumeiko, N., Suarez Gonzalez, J., Bansal, M., Bansal, S., Cornelis, T., De Wolf, E. A., Janssen, X., Luyckx, S., Mucibello, L., Ochesanu, S., Roland, B., Rougny, R., Selvaggi, M., Staykova, Z., Van Haevermaet, H., Van Mechelen, P., Van Remortel, N., Van Spilbeeck, A., Blekman, F., Blyweert, S., D’Hondt, J., Gonzalez Suarez, R., Kalogeropoulos, A., Maes, M., Olbrechts, A., Van Doninck, W., Van Mulders, P., Van Onsem, G. P., Villella, I., Clerbaux, B., De Lentdecker, G., Dero, V., Gay, A. P. R., Hreus, T., Léonard, A., Marage, P. E., Mohammadi, A., Reis, T., Thomas, L., Vander Marcken, G., Vander Velde, C., Vanlaer, P., Wang, J., Adler, V., Beernaert, K., Cimmino, A., Costantini, S., Garcia, G., Grunewald, M., Klein, B., Lellouch, J., Marinov, A., Mccartin, J., Ocampo Rios, A. A., Ryckbosch, D., Strobbe, N., Thyssen, F., Tytgat, M., Verwilligen, P., Walsh, S., Yazgan, E., Zaganidis, N., Basegmez, S., Bruno, G., Castello, R.
• Format: Journal Article
• Language: English
• Published: United States Springer 01.12.2012
• Subjects: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-012-2251-3

A measurement is presented of the relative prompt production rate of chi(c2) and chi(c1) with 4.6 inverse femtobarns of data collected by the CMS experiment at the LHC in pp collisions at sqrt(s) = 7 TeV. The two states are measured via their radiative decays chi(c) to J/psi + gamma, with the photon converting into a dielectron pair for J/psi rapidity abs(y(J/psi)) < 1.0 and photon transverse momentum pt(gamma) > 0.5 GeV. The measurement is given for six intervals of pt(J/psi) between 7 and 25 GeV. The results are compared to theoretical predictions.