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Published June 2018 | Submitted + Published + Erratum
Journal Article Open

Measurement of b hadron lifetimes in pp collisions at √s = 8 TeV


Measurements are presented of the lifetimes of the B^0, B^0_ s, Λ^0_b, and B+_c hadrons using the decay channels B^0→J/ψK∗(892)^0, B^0→J/ψK^0_S, B^0_s→J/ψπ^+π^−, B^0_s→J/ψϕ(1020), Λ^0_b→J/ψΛ^0, and B+_c→J/ψπ^+. The data sample, corresponding to an integrated luminosity of 19.7fb^(-1), was collected by the CMS detector at the LHC in proton–proton collisions at √s = 8 TeV. The B^0 lifetime is measured to be 453.0 ± 1.6(stat) ± 1.8(syst) μ m in J/ψK∗(892)^0 and 457.8 ± 2.7(stat) ± 2.8(syst) μ m in J/ψK^0_S, which results in a combined measurement of cτ_(B^0) = 454.1 ± 1.4(stat) ± 1.7(syst) μ m. The effective lifetime of the B^0_s meson is measured in two decay modes, with contributions from different amounts of the heavy and light eigenstates. This results in two different measured lifetimes: cτ_(B^0_s) → J/ψπ^+π^− = 502.7 ± 10.2(stat) ± 3.4(syst) μ m and cτ_(B^0_s) → J/ψϕ(1020) = 443.9 ± 2.0(stat) ± 1.5(syst) μ m. The Λ^0_b lifetime is found to be 442.9 ± 8.2(stat) ± 2.8(syst) μ m. The precision from each of these channels is as good as or better than previous measurements. The B+_c lifetime, measured with respect to the B+B+ to reduce the systematic uncertainty, is 162.3 ± 7.8(stat) ± 4.2(syst) ± 0.1(τ_(B+)) μ m. All results are in agreement with current world-average values.

Additional Information

© 2018 CERN for the benefit of the CMS collaboration. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Funded by SCOAP3. Received: 24 October 2017; Accepted: 25 May 2018. First Online: 07 June 2018. We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS, RFBR and RAEP (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI and FEDER (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract no. 675440 (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 Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS program of the Foundation for Polish Science, cofinanced from European Union, Regional Development Fund, the Mobility Plus program of the Ministry of Science and Higher Education, the National Science Center (Poland), contracts Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, and 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406; the National Priorities Research Program by Qatar National Research Fund; the Programa Severo Ochoa del Principado de Asturias; the Thalis and Aristeia programs cofinanced by EU-ESF and the Greek NSRF; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); the Welch Foundation, contract C-1845; and the Weston Havens Foundation (USA).

Attached Files

Published - Sirunyan2018_Article_MeasurementOfBHadronLifetimesI.pdf

Submitted - 1710.08949.pdf

Erratum - Sirunyan2018_Article_ErratumToMeasurementOfBHadronL.pdf


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