An amplitude analysis of B-→J/ψΛp¯ decays is performed using 4400 signal candidates selected on a data sample of pp collisions recorded at center-of-mass energies of 7, 8, and 13 TeV with the LHCb detector, corresponding to an integrated luminosity of 9 fb-1. A narrow resonance in the J/ψΛ system, consistent with a pentaquark candidate with strangeness, is observed with high significance. The mass and the width of this new state are measured to be 4338.2±0.7±0.4 MeV and 7.0±1.2±1.3 MeV, where the first uncertainty is statistical and the second systematic. The spin is determined to be 1/2 and negative parity is preferred. Because of the small Q-value of the reaction, the most precise single measurement of the B- mass to date, 5279.44±0.05±0.07 MeV, is obtained.

Observation of a J/ψ Λ Resonance Consistent with a Strange Pentaquark Candidate in B- →j/ψ Λ p ¯ Decays

Bassi G.
Membro del Collaboration Group
;
Kleijne N.
Membro del Collaboration Group
;
Lusiani A.
Membro del Collaboration Group
;
Morello M. J.
Membro del Collaboration Group
;
Pica L.
Membro del Collaboration Group
;
Ribatti R.
Membro del Collaboration Group
;
2023

Abstract

An amplitude analysis of B-→J/ψΛp¯ decays is performed using 4400 signal candidates selected on a data sample of pp collisions recorded at center-of-mass energies of 7, 8, and 13 TeV with the LHCb detector, corresponding to an integrated luminosity of 9 fb-1. A narrow resonance in the J/ψΛ system, consistent with a pentaquark candidate with strangeness, is observed with high significance. The mass and the width of this new state are measured to be 4338.2±0.7±0.4 MeV and 7.0±1.2±1.3 MeV, where the first uncertainty is statistical and the second systematic. The spin is determined to be 1/2 and negative parity is preferred. Because of the small Q-value of the reaction, the most precise single measurement of the B- mass to date, 5279.44±0.05±0.07 MeV, is obtained.
2023
Settore FIS/01 - Fisica Sperimentale
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/139986
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