Pentaquarks and resonances in the $pJ/\psi$ spectrum

TL;DR

This paper models exotic baryons with hidden charm as antiquark-diquark-diquark systems, estimating their masses, analyzing production data, and proposing interpretations for observed pentaquark peaks in the $pJ/$ spectrum.

Contribution

It introduces a new composite model for hidden charm pentaquarks and provides mass estimates and interpretations for experimental spectral features.

Findings

Narrow peak at 4450 MeV identified as negative parity pentaquark.

Broad bump at 4380 MeV attributed to rescattering effects.

Predictions made for positions of other negative parity pentaquarks.

Abstract

We consider exotic baryons with hidden charm as antiquark-diquark-diquark composite systems. Spin and isospin structure of such exotic states is given and masses are estimated. The data for production of pentaquarks in the reaction $\Lambda_b\to K^-p J/\psi$ are discussed. We suggest that the narrow peak in $pJ/\psi$ spectra at 4450 MeV is antiquark-diquark-diquark state with negative parity, $5/2^{-}(4450)$, while the broad bump $3/2^{+}(4380)$ is the result of rescatterings in the ($pJ/\psi$)-channel. Positions of other pentaquarks with negative parity are estimated.