6533b7d7fe1ef96bd1268142

RESEARCH PRODUCT

LHCb pentaquark as a D^* Sigma_c-D^* Sigma_c^* molecular state

subject

description

We perform a theoretical analysis of the Λb→J/ψK−p reaction from where a recent LHCb experiment extracts a Λ(1405) contribution in the K−p spectrum close to threshold and two baryon states of hidden charm in the J/ψp spectrum. We recall that baryon states of this type have been theoretically predicted matching the mass, width and JP of the experiment; concretely some states built up from the J/ψN, D¯∗Λc, D¯∗Σc, D¯Σ∗c and D¯∗Σ∗c coupled channels. We assume that the observed narrow state around 4450 MeV has this nature and we are able to describe simultaneously the shapes and relative strength of the the K−p mass distribution close to threshold and the peak of the J/ψp distribution, with values of the J/ψp coupling to the resonance in line with the theoretical ones. The nontrivial matching of many properties gives support to a JP=3/2− assignment to this state and to its nature as a molecular state mostly made of D¯∗Σc and D¯∗Σ∗c.