A full amplitude analysis of Λ_b^0→J/ψpπ^- decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb^-1. A significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations N→pπ^-, either the P_c(4380)^+ and P_c(4450)^+→J/ψp states, previously observed in Λ_b^0→J/ψpK^- decays, or the Z_c(4200)^-→J/ψπ^- state, previously reported in B^0→J/ψK^+π^- decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the P_c(4380)^+ and P_c(4450)^+ production rates expected from their previous observation taking account of Cabibbo suppression.
Evidence for Exotic Hadron Contributions to Λ_b^0→J/ψpπ^- Decays
VELTRI, MICHELE;
2016
Abstract
A full amplitude analysis of Λ_b^0→J/ψpπ^- decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb^-1. A significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations N→pπ^-, either the P_c(4380)^+ and P_c(4450)^+→J/ψp states, previously observed in Λ_b^0→J/ψpK^- decays, or the Z_c(4200)^-→J/ψπ^- state, previously reported in B^0→J/ψK^+π^- decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the P_c(4380)^+ and P_c(4450)^+ production rates expected from their previous observation taking account of Cabibbo suppression.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
