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Observation of the rare B_s^0 →µ+µ− decay from the combined analysis of CMS and LHCb data

Khachatryan, V. and Apresyan, A. and Bornheim, A. and Bunn, J. and Chen, Y. and Duarte, J. and Mott, A. and Newman, H. B. and Pena, C. and Pierini, M. and Spiropulu, M. and Vlimant, J. R. and Wilkinson, R. and Xie, S. and Zhu, R. Y. and Dubinin, M. (2015) Observation of the rare B_s^0 →µ+µ− decay from the combined analysis of CMS and LHCb data. Nature, 522 (7554). pp. 68-72. ISSN 0028-0836. http://resolver.caltech.edu/CaltechAUTHORS:20150626-152058579

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Abstract

The standard model of particle physics describes the fundamental particles and their interactions via the strong, electromagnetic and weak forces. It provides precise predictions for measurable quantities that can be tested experimentally. The probabilities, or branching fractions, of the strange B meson ( B_s^0) and the B^0 meson decaying into two oppositely charged muons (μ+ and μ−) are especially interesting because of their sensitivity to theories that extend the standard model. The standard model predicts that the B_s^0 →µ+µ− and B^0 →µ+µ− decays are very rare, with about four of the former occurring for every billion B_s^0 mesons produced, and one of the latter occurring for every ten billion B^0 mesons. A difference in the observed branching fractions with respect to the predictions of the standard model would provide a direction in which the standard model should be extended. Before the Large Hadron Collider (LHC) at CERN started operating, no evidence for either decay mode had been found. Upper limits on the branching fractions were an order of magnitude above the standard model predictions. The CMS (Compact Muon Solenoid) and LHCb (Large Hadron Collider beauty) collaborations have performed a joint analysis of the data from proton–proton collisions that they collected in 2011 at a centre-of-mass energy of seven teraelectronvolts and in 2012 at eight teraelectronvolts. Here we report the first observation of the µ+µ− decay, with a statistical significance exceeding six standard deviations, and the best measurement so far of its branching fraction. Furthermore, we obtained evidence for the B_s^0 →µ+µ− decay with a statistical significance of three standard deviations. Both measurements are statistically compatible with standard model predictions and allow stringent constraints to be placed on theories beyond the standard model. The LHC experiments will resume taking data in 2015, recording proton–proton collisions at a centre-of-mass energy of 13 teraelectronvolts, which will approximately double the production rates of B_s^0 and B^0 mesons and lead to further improvements in the precision of these crucial tests of the standard model.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1038/nature14474DOIArticle
http://www.nature.com/nature/journal/v522/n7554/full/nature14474.htmlPublisherArticle
http://arxiv.org/abs/1411.4413arXivDiscussion Paper
http://rdcu.be/dfUrPublisherFree Readcube access
ORCID:
AuthorORCID
Apresyan, A.0000-0002-6186-0130
Bornheim, A.0000-0002-0128-0871
Bunn, J.0000-0002-3798-298X
Chen, Y.0000-0003-2582-6469
Newman, H. B.0000-0003-0964-1480
Pierini, M.0000-0003-1939-4268
Spiropulu, M.0000-0001-8172-7081
Xie, S.0000-0003-2509-5731
Zhu, R. Y.0000-0003-3091-7461
Additional Information:© 2015 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution- NonCommercial-ShareAlike 3.0 Unported licence. The images or other third partymaterial in this article are included in the article’s Creative Commons licence, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons licence, users will need to obtain permission fromthe licence holder to reproduce thematerial. To view a copy of this licence, visit http://creativecommons. org/licenses/by-nc-sa/3.0 Received 12 November 2014; Accepted 31 March 2015; Published online 13 May 2015. We express our gratitude to colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at CERN, at the CMS institutes and at the LHCb institutes. 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 provided by CERN and by many funding agencies. The following agencies provide support for both CMS and LHCb: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and HGF (Germany); SFI (Ireland); INFN (Italy); NASU (Ukraine); STFC (UK); and NSF (USA). Agencies that provide support for CMS only are BMWFW and FWF (Austria); FNRS and FWO (Belgium); FAPESP (Brazil); MES (Bulgaria); CAS and MoST (China); COLCIENCIAS (Colombia); MSES and CSF(Croatia); RPF (Cyprus); MoER, ERC IUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA (France); GSRT (Greece); OTKA and NIH(Hungary); DAE and DST (India); IPM (Iran); NRF and WCU (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI(Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); SFFR (Ukraine); and DOE (USA). Agencies that provide support for only LHCb are: FINEP (Brazil); MPG (Germany); FOM and NWO (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FANO(Russia); MinECo (Spain); SNSF and SER (Switzerland). Individuals from the CMS collaboration have received support from the Marie Curie programme and the European Research Council and EPLANET (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 a` la Recherche dans l’Industrie et dans l’Agriculture (FRIABelgium); 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 programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund; the Compagnia di San Paolo(Torino); the Consorzio per la Fisica (Trieste); MIUR project 20108T4XTM (Italy); the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF; and the National Priorities Research Program by Qatar National Research Fund. Individual groups or members of the LHCb collaboration have received support from EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union), Conseil général de Haute-Savoie, Labex ENIGMASS and OCEVU, Région Auvergne(France), RFBR (Russia), XuntaGal and GENCAT (Spain), Royal Society and Royal Commission for the Exhibition of 1851 (UK). LHCb is also thankful for the computing resources and the access to software R&D tools provided by Yandex LLC (Russia). The CMS and LHCb collaborations are indebted to the communities behind the multiple open source software packages on which they depend. Author Contributions: All authors have contributed to the publication, being variously involved in the design and the construction of the detectors, in writing software, calibrating sub-systems, operating the detectors and acquiring data and finally analysing the processed data.
Group:CMS@Caltech
Funders:
Funding AgencyGrant Number
CERNUNSPECIFIED
CAPES, CNPq, FAPERJ and FINEP (Brazil)UNSPECIFIED
NSFC (China)UNSPECIFIED
CNRS/IN2P3 (France)UNSPECIFIED
BMBF, DFG and HGF (Germany)UNSPECIFIED
Science Foundation, IrelandUNSPECIFIED
Istituto Nazionale di Fisica Nucleare (INFN)UNSPECIFIED
NASU (Ukraine)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
NSFUNSPECIFIED
BMWFW and FWF (Austria)UNSPECIFIED
FNRS and FWO (Belgium) UNSPECIFIED
FAPESP (Brazil)UNSPECIFIED
MES (Bulgaria)UNSPECIFIED
CAS and MoST (China)UNSPECIFIED
COLCIENCIAS (Colombia)UNSPECIFIED
MSES and CSF (Croatia)UNSPECIFIED
RPF (Cyprus) UNSPECIFIED
MoER, ERC IUT and ERDF (Estonia)UNSPECIFIED
Academy of Finland,MEC, and HIP (Finland)UNSPECIFIED
Commissariat à l’Energie Atomique (CEA)UNSPECIFIED
GSRT (Greece)UNSPECIFIED
OTKA and NIH (Hungary) UNSPECIFIED
DAE and DST (India) UNSPECIFIED
IPM (Iran)UNSPECIFIED
NRF and WCU (Republic of Korea)UNSPECIFIED
LAS (Lithuania)UNSPECIFIED
MOE and UM (Malaysia)UNSPECIFIED
CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico)UNSPECIFIED
MBIE (New Zealand)UNSPECIFIED
PAEC (Pakistan)UNSPECIFIED
MSHE and NSC (Poland)UNSPECIFIED
Fundação para a Ciência e a Tecnologia (FCT)UNSPECIFIED
JINR (Dubna)UNSPECIFIED
MON, RosAtom, RAS and RFBR (Russia)UNSPECIFIED
MESTD (Serbia)UNSPECIFIED
SEIDI and CPAN (Spain)UNSPECIFIED
Swiss Funding Agencies (Switzerland)UNSPECIFIED
MST (Tapei)UNSPECIFIED
ThEPCenter, IPST, STAR and NSTDA (Thailand)UNSPECIFIED
TUBITAK and TAEK (Turkey) UNSPECIFIED
SFFR (Ukraine)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
FINEP (Brazil)UNSPECIFIED
MPG (Germany)UNSPECIFIED
FOM and NWO (The Netherlands)UNSPECIFIED
MNiSW and NCN (Poland)UNSPECIFIED
MEN/IFA (Romania)UNSPECIFIED
MinES and FANO (Russia)UNSPECIFIED
MINECO (Spain)UNSPECIFIED
SNSFand SER (Switzerland)UNSPECIFIED
Marie Curie programme and the European Research Council and EPLANET (European Union)UNSPECIFIED
Leventis Foundation UNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Belgian Federal Science Policy OfficeUNSPECIFIED
Fonds pour la Formation à la Recherche dans l’índustrie et dans l’Ágriculture (FRIA-Belgium)UNSPECIFIED
Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)UNSPECIFIED
Ministry of Education, Youth and Sports (MEYS) of Czech RepublicUNSPECIFIED
Council of Science and Industrial Research, IndiaUNSPECIFIED
HOMING PLUS programme of Foundation for Polish Science cofinanced from European UnionUNSPECIFIED
Compagnia di San Paolo (Torino)UNSPECIFIED
Consorzio per la Fisica (Trieste)UNSPECIFIED
MIUR project 20108T4XTM (Italy)UNSPECIFIED
Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRFUNSPECIFIED
National Priorities Research Program by Qatar National Research FundUNSPECIFIED
EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union)UNSPECIFIED
Conseil général de Haute-Savoie, Labex ENIGMASS and OCEVU, Région Auvergne (France)UNSPECIFIED
RFBR (Russia)UNSPECIFIED
XuntaGal and GENCAT (Spain)UNSPECIFIED
Royal Society and Royal Commission for the Exhibition of 1851 (United Kingdom)UNSPECIFIED
Issue or Number:7554
Record Number:CaltechAUTHORS:20150626-152058579
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150626-152058579
Official Citation:Collaboration, C. M. S., & Collaboration, L. H. (2015). Observation of the rare Bs0 →µ+µ− decay from the combined analysis of CMS and LHCb data. [Letter]. Nature, 522(7554), 68-72. doi: 10.1038/nature14474
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58646
Collection:CaltechAUTHORS
Deposited By: Joanne McCole
Deposited On:29 Jun 2015 20:44
Last Modified:20 Sep 2019 23:59

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