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Observation of the Doubly Charmed Baryon Ξcc+ with the LHCb Run 3 Detector

  • LHCb Collaboration

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The first observation of the doubly charmed baryon Ξcc+ is reported through its decay to the Λc+K-π+ final state, with a statistical significance exceeding seven standard deviations. The observation is made using proton-proton collision data collected in 2024 with the LHCb Run 3 detector at a center-of-mass energy of 13.6 TeV, corresponding to a total integrated luminosity of 6.9 fb-1. The Ξcc+ mass is measured to be 3619.97±0.83±0.26-1.30+1.90 MeV/c2, where the first uncertainty is statistical, the second is systematic, and the third is due to the unknown Ξcc+ lifetime, which is assumed to lie in the range 15-160 fs with a baseline value of 45 fs. The difference between the masses of the Ξcc+ and Ξcc++ baryons is determined to be -1.77±0.84±0.15-1.30+1.90 MeV/c2. This is the first observation of a new particle made with the LHCb Run 3 detector.

Original languageEnglish
Article number021902
Pages (from-to)1-14
Number of pages14
JournalPhysical review letters
Volume137
Issue number2
Early online date8 Jul 2026
DOIs
Publication statusPublished - 10 Jul 2026

Bibliographical note

Publisher Copyright:
© 2026 CERN, for the LHCb Collaboration.

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: ARC (Australia); CAPES, CNPq, FAPERJ, and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 and CEA (France); BMFTR, DFG, and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEC/IFA (Romania); MICIU and AEI (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (USA). We acknowledge the computing resources that are provided by ARDC (Australia), CBPF (Brazil), CERN, IHEP, and LZU (China), IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), Polish WLCG (Poland), IFIN-HH (Romania), PIC (Spain), CSCS (Switzerland), GridPP (United Kingdom), and NSF (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 RTP (Australia); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP (China); Minciencias (Colombia); EPLANET, Marie Skłodowska-Curie Actions, ERC, and NextGenerationEU (European Union); A*MIDEX, ANR, IPhU, Labex P2IO, and Région Auvergne-Rhône-Alpes (France); Alexander-von-Humboldt Foundation (Germany); ICSC (Italy); Severo Ochoa and María de Maeztu Units of Excellence, GVA, XuntaGal, GENCAT, InTalent-Inditex and Prog. Atracción Talento CM (Spain); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom). 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: ARC (Australia); CAPES, CNPq, FAPERJ, and FINEP (Brazil); MOST and NSFC (China); CNRS/IN2P3 and CEA (France); BMFTR, DFG, and MPG (Germany); INFN (Italy); NWO (Netherlands); MNiSW and NCN (Poland); MEC/IFA (Romania); MICIU and AEI (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); DOE NP and NSF (USA). We acknowledge the computing resources that are provided by ARDC (Australia), CBPF (Brazil), CERN, IHEP, and LZU (China), IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (Netherlands), Polish WLCG (Poland), IFIN-HH (Romania), PIC (Spain), CSCS (Switzerland), GridPP (United Kingdom), and NSF (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 RTP (Australia); Key Research Program of Frontier Sciences of CAS, CAS PIFI, CAS CCEPP (China); Minciencias (Colombia); EPLANET, Marie Sklodowska-Curie Actions, ERC, and NextGenerationEU (European Union); A∗MIDEX, ANR, IPhU, Labex P2IO, and Région Auvergne-Rhône-Alpes (France); Alexander-von-Humboldt Foundation (Germany); ICSC (Italy); Severo Ochoa and María de Maeztu Units of Excellence, GVA, XuntaGal, GENCAT, InTalent-Inditex and Prog. Atracción Talento CM (Spain); the Leverhulme Trust, the Royal Society, and UKRI (United Kingdom).

Funders
Ministerio de Ciencia, Innovación y Universidades
Institutul National de Cercetare-Dezvoltare pentru Fizica si Inginerie Nucleara 'Horia Hulubei'
Agence Nationale de la Recherche
Australian Research Council
RTP (Australia)
Australian Research Data Commons
National Academy of Sciences of Ukraine
Ministerul Educaţiei şi Cercetării
Narodowe Centrum Nauki
National Science Foundation
IPhU (France)
Institut national de physique nucléaire et de physique des particules
Science and Technology Facilities Council
H2020 Marie Skłodowska-Curie Actions
CEA (France)
NASU (Ukraine)
Key Research Program of Frontier Sciences of CAS (China)
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Prog. Atracción Talento CM (Spain)
DOE NP (USA)
Leverhulme Trust
Labex P2IO (France)
RTP
CAS PIFI (China)
DFG (Germany)
SURF
ICSC (Italy)
Financiadora de Estudos e Projetos
Centre National de la Recherche Scientifique
Max-Planck-Gesellschaft
InTalent-Inditex (Spain)
NSF
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Karlsruhe Institute of Technology
Deutsche Forschungsgemeinschaft
European Commission
Région Auvergne-Rhône-Alpes
International Council of Shopping Centers
Lanzhou University
Agencia Estatal de Investigación
CAS Center for Excellence in Particle Physics
Institutul de Fizică Atomică
Ministry of Science and Technology of the People's Republic of China
GridPP
Institute of High Energy Physics, Chinese Academy of Sciences
GENCAT (Spain)
Ministerio de Ciencia, Tecnología e Innovación
BMFTR (Germany)
BMFTR
Deutsches Elektronen-Synchrotron
CNRS/IN2P3 (France)
Narodowym Centrum Nauki
Chinese Academy of Sciences
SER (Switzerland)
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
Key Research Program of Frontier Science, Chinese Academy of Sciences
NextGenerationEU
Royal Society
Sociedad Española de Reumatología
European Research Council
EPLANET
XuntaGal (Spain)
Ministerstwo Edukacji i Nauki
the Royal Society (United Kingdom)
Severo Ochoa and María de Maeztu Units of Excellence (Spain)
A*MIDEX (France)
Generalitat Valenciana
CERN
Nuclear Physics
WLCG
Alexander von Humboldt-Stiftung
CBPF
Istituto Nazionale di Fisica Nucleare
UK Research and Innovation
National Natural Science Foundation of China

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