Evidence of a J/ψΛ structure and observation of excited Ξ- states in the Ξb -→J/ψΛK- decay

LHCb Collaboration

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

First evidence of a structure in the J/ψΛ invariant mass distribution is obtained from an amplitude analysis of Ξb -→J/ψΛK- decays. The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1σ including systematic uncertainties and look-elsewhere effect. Its mass and width are determined to be 4458.8±2.9-1.1 +4.7MeV and 17.3±6.5-5.7 +8.0MeV, respectively, where the quoted uncertainties are statistical and systematic. The structure is also consistent with being due to two resonances. In addition, the narrow excited Ξ- states, Ξ1690- and Ξ1820-, are seen for the first time in a Ξb - decay, and their masses and widths are measured with improved precision. The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb-1, collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV.

Original languageEnglish
Pages (from-to)1278-1287
Number of pages10
JournalScience Bulletin
Volume66
Issue number13
Early online date9 Mar 2021
DOIs
Publication statusPublished - 15 Jul 2021

Bibliographical note

Publisher Copyright:
© 2021 Science China Press

Funding

The numerical calculations for this paper have been supported by the Supercomputing Center of Wuhan University. 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); MOST and NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MSHE (Russia); MICINN (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (USA). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (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); A*MIDEX, ANR, Labex P2IO and OCEVU, and Région Auvergne-Rhône-Alpes (France); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP, Fundamental Research Funds for the Central Universities, and Sci. & Tech. Program of Guangzhou (China); RFBR, RSF and Yandex LLC (Russia); GVA, XuntaGal and GENCAT (Spain); the Royal Society and the Leverhulme Trust (United Kingdom).

FundersFunder number
Agence Nationale de la Recherche
National Academy of Sciences of Ukraine
Narodowe Centrum Nauki
OCEVU
National Science Foundation
Institut national de physique nucléaire et de physique des particules
H2020 Marie Skłodowska-Curie Actions
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Ministerio de Ciencia e Innovación
Ministry of Science and Technology, Taiwan
Program of Guangzhou
Leverhulme Trust
PL-GRID
MSHE
SURF
Instituto Nazionale di Fisica Nucleare
Financiadora de Estudos e Projetos
Centre National de la Recherche Scientifique
Bundesministerium für Bildung und Forschung
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Karlsruhe Institute of Technology
Deutsche Forschungsgemeinschaft
Région Auvergne-Rhône-Alpes
Russian Foundation for Basic Research
U.S. Department of Energy
Yandex LLC
CAS CCEPP
GridPP
RRCKI
Russian Science Foundation
Deutsches Elektronen-Synchrotron
Chinese Academy of Sciences
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
XuntaGal
Key Research Program of Frontier Sciences of CAS
Royal Society
Sociedad Española de Reumatología
European Research Council
EPLANET
Ministerstwo Edukacji i Nauki
Generalitat Valenciana
CERN
Fundamental Research Funds for the Central Universities
Alexander von Humboldt-Stiftung
National Natural Science Foundation of China
Science and Technology Facilities CouncilST/V003399/1

    Keywords

    • Exotics
    • Particle and resonance production
    • Pentaquark
    • QCD
    • Quarkonium
    • Spectroscopy

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