Identification of b-quark jets with the CMS experiment

Chatrchyan, S. and Khachatryan, V. and Sirunyan, A. M. and Tumasyan, A. and Adam, W. and Aguilo, E. and Bergauer, T. and Dragicevic, M. and Ero, J. and Fabjan, C. and Friedl, M. and Fruhwirth, R. and Ghete, V. M. and Hammer, J. and Hormann, N. and Hrubec, J. and Jeitler, M. and Kiesenhofer, W. and Knunz, V. and Krammer, M. and Kratschmer, I. and Liko, D. and Mikulec, I. and Pernicka, M. and Rahbaran, B. and Rohringer, C. and Rohringer, H. and Schofbeck, R. and Strauss, J. and Taurok, A. and Bencze, György and Hajdu, Csaba and Hidas, Pál and Horváth, Dezső and Siklér, Ferenc and Veszprémi, Viktor and Vesztergombi, György and Molnár, József and Pálinkás, József and Karancsi, János and Raics, Péter and Trócsányi, Zoltán and Ujvári, Balázs and Veres, Gábor and Krajczár, Krisztián (2013) Identification of b-quark jets with the CMS experiment. JOURNAL OF INSTRUMENTATION, 8 (4). ISSN 1748-0221

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Abstract

At the Large Hadron Collider, the identification of jets originating from b quarks is important for searches for new physics and for measurements of standard model processes. A variety of algorithms has been developed by CMS to select b-quark jets based on variables such as the impact parameters of charged-particle tracks, the properties of reconstructed decay vertices, and the presence or absence of a lepton, or combinations thereof. The performance of these algorithms has been measured using data from proton-proton collisions at the LHC and compared with expectations based on simulation. The data used in this study were recorded in 2011 at √s = 7 TeV for a total integrated luminosity of 5.0 fb−1. The efficiency for tagging b-quark jets has been measured in events from multijet and t-quark pair production. CMS has achieved a b- jet tagging efficiency of 85% for a light-parton misidentification probability of 10% in multijet events. For analyses requiring higher purity, a misidentification probability of only 1.5% has been achieved, for a 70% b-jet tagging efficiency.

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