The LHCb trigger and its performance in 2011

R. Aaij, J. Albrecht, F. Alessio, S. Amato, E. Aslanides, I. Belyaev, M. Van Beuzekom, E. Bonaccorsi, R. Bonnefoy, L. Brarda, O. Callot, M. Cattaneo, H. Chanal, M. Chebbi, X. Cid Vidal, M. Clemencic, J. Closier, V. Coco, J. Cogan, O. DeschampsH. Dijkstra, C. Drancourt, R. Dzhelyadin, M. Frank, M. Gandelman, C. Gaspar, V. V. Gligorov, C. Göbel, L. A. Granado Cardoso, Yu Guz, C. Haen, J. He, E. Van Herwijnen, W. Hulsbergen, R. Jacobsson, B. Jost, T. M. Karbach, U. Kerzel, P. Koppenburg, G. Krocker, C. Langenbruch, I. Lax, R. Le Gac, R. Lefèvre, J. Lefrançois, O. Leroy, L. Li Gioi, G. Liu, F. Machefert, I. V. Machikhiliyan, M. Magne, G. Mancinelli, U. Marconi, A. Martín Sánchez, M. -N Minard, S. Monteil, N. Neufeld, V. Niess, S. Oggero, A. Pérez-Calero Yzquierdo, P. Perret, M. Perrin-Terrin, B. Pietrzyk, A. Puig Navarro, G. Raven, P. Robbe, H. Ruiz, M. H. Schune, R. Schwemmer, J. Serrano, I. Shapoval, T. Skwarnicki, B. Souza De Paula, P. Spradlin, S. Stahl, V. K. Subbiah, S. T'Jampens, F. Teubert, C. Thomas, M. Vesterinen, M. Williams, M. Witek, A. Zvyagin

Research output: Contribution to journalArticlepeer-review

426 Scopus citations


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.

Original languageEnglish (US)
Article numberP04022
JournalJournal of Instrumentation
Issue number4
StatePublished - Apr 1 2013


  • Trigger algorithms
  • Trigger concepts and systems (hardware and software)

ASJC Scopus subject areas

  • Instrumentation
  • Mathematical Physics


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