The first observation of the doubly charmed baryon Xicc+ is reported through its decay to the Lambdac+K-pi+ 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 Xicc+ mass is measured to be 3619.97 \pm 0.83 \pm 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 Xicc+ 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 Xicc+ and Xicc++ baryons is determined to be -1.77 \pm0.84 \pm 0.15-1.30+1.90 MeV/c2. This is the first observation of a new particle made with the LHCb Run 3 detector.
Observation of the Doubly Charmed Baryon Xicc+ with the LHCb Run 3 Detector
Celestino I.Membro del Collaboration Group
;Cordova G.Membro del Collaboration Group
;Kleijne N.Membro del Collaboration Group
;Morello M. J.Membro del Collaboration Group
;Passaro D.Membro del Collaboration Group
;Pica L.Membro del Collaboration Group
;Riccardi D.Membro del Collaboration Group
;Xu A.Membro del Collaboration Group
;
2026
Abstract
The first observation of the doubly charmed baryon Xicc+ is reported through its decay to the Lambdac+K-pi+ 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 Xicc+ mass is measured to be 3619.97 \pm 0.83 \pm 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 Xicc+ 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 Xicc+ and Xicc++ baryons is determined to be -1.77 \pm0.84 \pm 0.15-1.30+1.90 MeV/c2. This is the first observation of a new particle made with the LHCb Run 3 detector.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.



