Measurement of the Λ_b cross section and the Λ_b to Λ_b ratio with J/ψΛ decays in pp collisions at √s = 7 TeV

Creators: Chatrchyan, S.; Apresyan, A.; Bornheim, A.; Chen, Y.; Di Marco, E.; Duarte, J.; Gataullin, M.; Ma, Y.; Mott, A.; Newman, H. B.; Rogan, C.; Timciuc, V.; Traczyk, P.; Veverka, J.; Wilkinson, R.; Yang, Y.; Zhu, R. Y.; Spiropulu, M.; Dubinin, M.; CMS Collaboration

Abstract

The Λ_b differential production cross section and the cross section ratio σ(Λ_b)/σ(Λ_b) are measured as functions of transverse momentum p^(Λb)_T and rapidity |y^(Λb)| in pp collisions at √ s = 7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Λ_b decays reconstructed in the exclusive final state J/ψΛ, with the subsequent decays J/ψ →μ^+μ^− and Λ→pπ, using a data sample corresponding to an integrated luminosity of 1.9 fb^(−1). The product σ(Λ_b) × B(Λ_b→J/ψΛ) versus p^(Λb) _T falls faster than that of b mesons. The measured value of σ(Λ_b) × B(Λ_b→J/ψΛ) for p^(Λb)_T > 10 GeV and |y^(Λb)| < 2.0 is 1.16±0.06±0.12 nb, and the integrated σ(Λ_b)/σ(Λ_b) ratio is 1.02±0.07±0.09, where the uncertainties are statistical and systematic, respectively.

Additional Information

© 2012 CERN for the benefit of the CMS Collaboration. Published by Elsevier B.V. This article is published Open Access at sciencedirect.com. It is distributed under the terms of the Creative Commons Attribution License 3.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited. Received 4 May 2012. Received in revised form 25 May 2012. Accepted 29 May 2012 Available online 1 June 2012. Editor: M. Doser. We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council (European Union); the Leventis Foundation; the A.P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Council of Science and Industrial Research, India; and the HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund.

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