https://doi.org/10.1140/epja/i2018-12498-1
Regular Article - Theoretical Physics
A meson-baryon molecular interpretation for some 
excited states
Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain
* e-mail: ramos@fqa.ub.edu
Received:
16
January
2018
Accepted:
18
March
2018
Published online:
25
April
2018
We explore the possibility that some of the five narrow resonances recently observed at LHCb could correspond to pentaquark states, structured as meson-baryon bound states or molecules. The interaction of the low-lying pseudoscalar mesons with the ground-state baryons in the charm +1 , strangeness -2 and isospin 0 sector is built from t-channel vector meson exchange, using effective Lagrangians. The resulting s-wave coupled-channel unitarized amplitudes show the presence of two structures with similar masses and widths to those of the observed 
and 
. The identification of these resonances with the meson-baryon bound states found in this work would also imply assigning the values 
for their spin-parity. An experimental determination of the spin-parity of the 
would contribute to a better understanding of its structure, as the quark-based models predict its spin-parity to be either 
or 
. Predictions for the analogue bottom 
resonances are also given.
© SIF, Springer-Verlag GmbH Germany, part of Springer Nature, 2018
