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Free keywords:
Bottom baryons, Charm quark, Heavy baryons, Parity, Spin
MPINP:
LHCb - Abteilung Hinton
Abstract:
The Ξb0(−) → Ξc(3055)+(0)(→D+(0)Λ)π− decay chains are observed, and the spin-parity of Ξc(3055)+(0) baryons is determined for the first time. The measurement is performed using proton-proton collision data at a center-of-mass energy of √s =13 TeV, corresponding to an integrated luminosity of 5.4 fb−1, recorded by the LHCb experiment between 2016 and 2018. The spin-parity of the Ξc(3055)+(0) baryons is determined to be 3/2+ with a significance of more than 6.5σ (3.5σ) compared to all other tested hypotheses. The up-down asymmetries of the Ξb0(−) → Ξc(3055)+(0)π− transitions are measured to be −0.92±0.10±0.05 (−0.92±0.16±0.22), consistent with maximal parity violation, where the first uncertainty is statistical and the second is systematic. These results support the hypothesis that the Ξc(3055)+(0) baryons correspond to the first D-wave λ-mode excitation of the Ξc flavor triplet.