Diquark-diquark-antiquark model for pentaquarks with hidden charm: current status and problems

TL;DR

This paper reviews the diquark-diquark-antiquark model for hidden-charm pentaquarks, addressing current challenges in mass estimation, decay modes, unitarity constraints, and hadronic components, in light of LHCb observations.

Contribution

It provides a comprehensive analysis of the diquark-diquark-antiquark model for pentaquarks, highlighting unresolved issues and theoretical constraints.

Findings

Identification of challenges in mass and mass splitting estimations.

Analysis of decay modes within the quark recombination framework.

Discussion of unitarity and analyticity constraints on pentaquark propagators.

Abstract

The $J/\psi p$ signals at 4380 MeV and 4450 MeV which were seen by the LHCb collaboration in the decay $\Lambda^0_b\to K^-J/\psi p$ are discussed following the hypothesis of the existence of diquark-diquark-antiquark composite states. The discussed problems concern: (i) estimation of masses and mass splittings for low-lying states, (ii) determination of decay modes in the quark recombination scheme, (iii) unitarity and analyticity constrains for pentaquark propagators, (iv) hadronic deuteron-like components in the diquark-diquark-antiquark multiplet.