Speaker
Sheldon Stone
(Syracuse University (US))
Description
Observations of exotic structures in the $J/\psi p$ channel, that we refer to as pentaquark-charmonium states, in $\Lambda_b^0 \to J/\psi p K^-$ 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 is performed on the three-body final state that reproduces all the angular and two-body mass distributions in the decay chain. To obtain a satisfactory fit of the structures seen in the $J/\psi p$ mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. We also discuss the related amplitude analysis that measured unambiguously the spin-parity of the $Z_c(4430)^+$ state that decays into $\psi$'$\pi^+$
Author
Sheldon Stone
(Syracuse University (US))
