Measurement of the Underlying Event Activity in Proton-Proton Collisions at 0.9 TeV

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2010, Vol.70, p.555-572
• Main Authors: Khachatryan, V., Sirunyan, A.M., Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Ero, J., Fabjan, C., Friedl, M., Fruhwirth, R., Ghete, V.M., Hammer, J., Hänsel, S., Hoch, M., Hörmann, N., Hrubec, J., Jeitler, M., Kasieczka, G., Kiesenhofer, W., Krammer, M., Liko, D., Mikulec, I., Pernicka, M., Rohringer, H., Schöfbeck, R., Strauss, J., Taurok, A., Teischinger, F., Mossolov, V., Shumeiko, N., Suarez Gonzalez, J., Benucci, L., Ceard, L., Dewolf, E.A., Hashemi, M., Janssen, X., Maes, T., Mucibello, L., Ochesanu, S., Roland, B., Rougny, R., Selvaggi, M., van Haevermaet, H., van Mechelen, P., van Remortel, N., Adler, V., Beauceron, S., Blyweert, S., d'Hondt, J., Devroede, O., Kalogeropoulos, A., Maes, J., Maes, M., Tavernier, S., van Doninck, W., van Mulders, P., Villella, I., Chabert, E.C., Charaf, O., Clerbaux, B., de Lentdecker, G., Dero, V., Gay, A.P.R., Hammad, G.H., Marage, P.E., Vander Velde, C., Vanlaer, P., Costantini, S., Grunewald, M., Klein, B., Marinov, A., Ryckbosch, D., Thyssen, F., Tytgat, M., Vanelderen, L., Verwilligen, P., Zaganidis, N., Basegmez, S., Bruno, G., Caudron, J., de Favereau de Jeneret, J., Delaere, C., Demin, P., Favart, D., Giammanco, A., Grégoire, G., Hollar, J., Lemaitre, V., Militaru, O., Ovyn, S., Pagano, D., Pin, A., Piotrzkowski, K., Quertenmont, L., Schul, N., Beliy, N., Caebergs, T., Daubie, E., Alves, G.A., Carneiro, M.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-010-1453-9

A measurement of the underlying activity in scattering processes with transverse momentum scale in the GeV region is performed in proton-proton collisions at sqrt(s) = 0.9 TeV, using data collected by the CMS experiment at the LHC. Charged hadron production is studied with reference to the direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally predict too little production of charged hadrons with pseudorapidity eta < 2, p_T > 0.5 GeV/c, and azimuthal direction transverse to that of the leading object.