The LHCb Trigger and its Performance in 2011

• Published in: arXiv.org 2013-04
• Main Authors: Aaij, R, Albrecht, J, Alessio, F, Amato, S, Aslanides, E, Belyaev, I, vanBeuzekom, M, Bonaccorsi, E, Bonnefoy, R, Brarda, L, Callot, O, Cattaneo, M, Chanal, H, Chebbi, M, CidVidal, X, Clemencic, M, Closier, J, Coco, V, Cogan, J, Deschamps, O, Dijkstra, H, Drancourt, C, Dzhelyadin, R, Frank, M, Gandelman, M, Gaspar, C, Gligorov, V V, Göbel, C, GranadoCardoso, L A, Yu Guz, Haen, C, J He, vanHerwijnen, E, Hulsbergen, W, Jacobsson, R, Jost, B, Karbach, T M, Kerzel, U, Koppenburg, P, Krocker, G, Langenbruch, C, Lax, I, LeGac, R, Lefèvre, R, Lefrançois, J, Leroy, O, LiGioi, L, Liu, G, Machefert, F, Machikhiliyan, I V, Magne, M, Mancinelli, G, Marconi, U, MartínSánchez, A, M -N Minard, Monteil, S, Neufeld, N, Niess, V, Oggero, S, Pérez-CaleroYzquierdo, A, Perret, P, Perrin-Terrin, M, Pietrzyk, B, PuigNavarro, A, Raven, G, Robbe, P, Ruiz, H, M -H Schune, Schwemmer, R, Serrano, J, Shapoval, I, Skwarnicki, T, SouzaDePaula, B, Spradlin, P, Stahl, S, Subbiah, V K, T'Jampens, S, Teubert, F, Thomas, C, Vesterinen, M, Williams, M, Witek, M, Zvyagin, A
• Format: Article
• Language: English
• Subjects: Charm (particle physics); Decay; Hadrons; Leptons; Performance evaluation
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1211.3055

This paper presents the design of the LHCb trigger and its performance on data taken at the LHC in 2011. A principal goal of LHCb is to perform flavour physics measurements, and the trigger is designed to distinguish charm and beauty decays from the light quark background. Using a combination of lepton identification and measurements of the particles' transverse momenta the trigger selects particles originating from charm and beauty hadrons, which typically fly a finite distance before decaying. The trigger reduces the roughly 11\,MHz of bunch-bunch crossings that contain at least one inelastic \(pp\) interaction to 3\,kHz. This reduction takes place in two stages; the first stage is implemented in hardware and the second stage is a software application that runs on a large computer farm. A data-driven method is used to evaluate the performance of the trigger on several charm and beauty decay modes.