# EPS HEP 2015

22-29 July 2015
Europe/Vienna timezone

## Pentaquarks and Tetraquarks at LHCb

Jul 23, 2015, 10:15 AM
15m

### 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 $\psi$'$\pi^+$

### Primary author

Sheldon Stone (Syracuse University (US))