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Published June 22, 2012 | Published
Journal Article Open

Observation of a New Ξ_b Baryon


The observation of a new b baryon via its strong decay into Ξ_b^-π^+ (plus charge conjugates) is reported. The measurement uses a data sample of pp collisions at √s=7  TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 5.3  fb^(-1). The known Ξb- baryon is reconstructed via the decay chain Ξ_b^-→J/ψΞ^-→μ^+μ^-Λ^0π^-, with Λ^0→pπ^-. A peak is observed in the distribution of the difference between the mass of the Ξ^b^-π^+ system and the sum of the masses of the Ξ_b^- and π^+, with a significance exceeding 5 standard deviations. The mass difference of the peak is 14.84±0.74(stat)±0.28(syst)  MeV. The new state most likely corresponds to the J^P=3/2^+ companion of the Ξ_b.

Additional Information

© 2012 CERN, for the CMS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Received 26 April 2012; published 21 June 2012. We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA).

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Published - PhysRevLett.108.252002.pdf


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August 19, 2023
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