Observations of exotic structures in the J/ψp channel, which we refer to as charmonium-pentaquark states, in Λb0→J/ψK-p decays are presented. The data sample corresponds to an integrated luminosity of 3fb-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/ψp 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±8±29MeV and a width of 205±18±86MeV, while the second is narrower, with a mass of 4449.8±1.7±2.5MeV and a width of 39±5±19MeV. The preferred JP assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.

Observation of J /ψp resonances consistent with pentaquark states in Λb0 →j /ψK-p decays

COGONI, VIOLETTA;Dettori, F.;Lai, A.;MANCA, GIULIA;OLDEMAN, RUDOLF GERHARD CHRISTIAAN;SAITTA, BIAGIO;VACCA, CLAUDIA;
2015

Abstract

Observations of exotic structures in the J/ψp channel, which we refer to as charmonium-pentaquark states, in Λb0→J/ψK-p decays are presented. The data sample corresponds to an integrated luminosity of 3fb-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/ψp 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±8±29MeV and a width of 205±18±86MeV, while the second is narrower, with a mass of 4449.8±1.7±2.5MeV and a width of 39±5±19MeV. The preferred JP assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.
Physics and astronomy; Baryons; Meson; Model; Distributions; Charmonium; Collisions; Hadrons
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/185121
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