论文信息 - Observation of J/p resonances consistent with pentaquark states in 0b J/K-p decays

Observation of J/p resonances consistent with pentaquark states in 0b J/K-p decays

Observations of exotic structures in the J= ψ p channel, which we refer to as charmonium-pentaquark states, in Λ 0 b → J= ψ K − p decays are presented. The data sample corresponds to an integrated luminosity of 3 fb − 1 acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis of the three-body final state reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J= ψ p mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380 (cid:1) 8 (cid:1) 29 MeV and a width of 205 (cid:1) 18 (cid:1) 86 MeV, while the second is narrower, with a mass of 4449 . 8 (cid:1) 1 . 7 (cid:1) 2 . 5 MeV and a width of 39 (cid:1) 5 (cid:1) 19 MeV. The preferred J P assignments are of opposite parity, with one state having spin 3 = 2 and the other 5 = 2 .

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