On the hidden charm pentaquark-s in ${\Lambda }_b\to J/\psi K^{-}p$ decay

Abstract

In a previous work we presented a theoretical analysis of the ${\Lambda }_b\to J/\psi K^{-}p$ reaction from where a recent experiment by the LHCb collaboration at CERN claimed the existence of two hidden charm pentaquarks, $P_c(4380{)}^{+}$ and $P_c(4450{)}^{+}$. In that work we focused only on the $\Lambda (1405)$ and $P_c(4450{)}^{+}$ signals and discussed the possible explanation of this pentaquark state within the picture of a dynamical meson-baryon molecule made up mostly from ${\bar{D}}^{\ast }{\Sigma }_c$ and ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$ components. In the present work we improve upon the previous one by considering the total $K^{-}p$ and $J/\psi p$ data including all the relevant resonances contributing to the spectra, and discuss the possible nature of both $P_c(4380{)}^{+}$ and $P_c(4450{)}^{+}$. We also discuss several important topics, like the effect of the contact term in the reaction, the viability of reproducing the data without the $P_c(4380{)}^{+}$ and the possible quantum numbers assignment to these pentaquarks.

Comments: 12 pages, 10 figures