Abstract
Differences in the behaviour of matter and antimatter have been observed in K and B meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as CP violation. Here, using data from the LHCb experiment at the Large Hadron Collider, we search for CP-violating asymmetries in the decay angle distributions of Λb0 baryons decaying to pπ- π+ π- and pπ-K+K- final states. These four-body hadronic decays are a promising place to search for sources of CP violation both within and beyond the standard model of particle physics. We find evidence for CP violation in Λb 0 to pπ- π+ π- decays with a statistical significance corresponding to 3.3 standard deviations including systematic uncertainties. This represents the first evidence for CP violation in the baryon sector.
Original language | English |
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Pages (from-to) | 391-396 |
Number of pages | 6 |
Journal | Nature Physics |
Volume | 13 |
Issue number | 4 |
DOIs | |
Publication status | Published - Apr 2017 |
Funding
We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative staff at the LHCb institutes. We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); FOM and NWO (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FASO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (The Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and OSC (USA). We are indebted to the communities behind the multiple open source software packages on which we depend. Individual groups or members have received support from AvH Foundation (Germany), EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union), Conseil Général de Haute-Savoie, Labex ENIGMASS and OCEVU, Région Auvergne (France), RFBR and Yandex LLC (Russia), GVA, XuntaGal and GENCAT (Spain), Herchel Smith Fund, The Royal Society, Royal Commission for the Exhibition of 1851 and the Leverhulme Trust (United Kingdom).
Funders | Funder number |
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Conseil Général de Haute-Savoie | |
EPLANET | |
GridPP | |
Herchel Smith Fund | |
Labex ENIGMASS | |
MinES | |
OCEVU | |
PL-GRID | |
RRCKI | |
SURF | |
Yandex LLC | |
National Science Foundation | |
Alexander von Humboldt-Stiftung | |
Karlsruhe Institute of Technology | |
H2020 Marie Skłodowska-Curie Actions | |
CERN | |
Institutul National de Cercetare-Dezvoltare pentru Fizica si Inginerie Nucleara 'Horia Hulubei' | |
Science and Technology Facilities Council | |
Leverhulme Trust | |
Royal Society | |
Royal Commission for the Exhibition of 1851 | |
European Commission | |
European Research Council | |
Deutsches Elektronen-Synchrotron | |
Deutsche Forschungsgemeinschaft | |
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung | 166208 |
Stichting voor Fundamenteel Onderzoek der Materie | |
National Natural Science Foundation of China | |
Russian Foundation for Basic Research | |
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior | |
Bundesministerium für Bildung und Forschung | |
Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
Generalitat Valenciana | |
Conselho Nacional de Desenvolvimento Científico e Tecnológico | |
Instituto Nazionale di Fisica Nucleare | |
Narodowe Centrum Nauki | |
Ministerstwo Edukacji i Nauki | |
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro | |
National Academy of Sciences of Ukraine | |
Centre National de la Recherche Scientifique | |
Financiadora de Estudos e Projetos | |
Région Auvergne-Rhône-Alpes | |
Institut national de physique nucléaire et de physique des particules | |
Federal Agency for Scientific Organizations | |
Sociedad Española de Reumatología |