Measurement of matter-antimatter differences in beauty baryon decays

R. Aaij, B. Adeva, M. Adinolfi, Z. Ajaltouni, S. Akar, J. Albrecht, F. Alessio, M. Alexander, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, S. Amerio, Y. Amhis, LA Everse, L. Anderlini, G. Andreassi, M. Andreotti, J.E. AndrewsR. B. Appleby, F. Archilli, P. d'Argent, J. Arnau Romeu, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, M. Baalouch, I. Babuschkin, K. Carvalho Akiba, V. Coco, P. N.Y. David, K. De Bruyn, M. Ferro-Luzzi, T. Ketel, R. F. Koopman, J. Van Leerdam, M. Merk, C. J.G. Onderwater, G. Raven, M. Schiller, N. Serra, H. Snoek, B. Storaci, V. Syropoulos, J. Van Tilburg, S. Tolk, P. Tsopelas, N. Tuning, The LHCb collaboration

Research output: Contribution to JournalArticleAcademicpeer-review

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 languageEnglish
Pages (from-to)391-396
Number of pages6
JournalNature Physics
Volume13
Issue number4
DOIs
Publication statusPublished - 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).

FundersFunder number
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 Forschung166208
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

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