Some Predictions of Diquark Model for Hidden Charm Pentaquark Discovered at the LHCb

TL;DR

This paper discusses predictions of the diquark model for hidden charm pentaquarks observed at LHCb, proposing specific flavor multiplet structures and decay rate relations as tests for the model.

Contribution

It provides new predictions for pentaquark multiplet structures and decay relations based on the diquark model, offering experimental tests for this theoretical framework.

Findings

Predicted flavor octet and decuplet multiplets for pentaquarks.

Derived decay rate ratios for b-baryon decays into pentaquarks.

Proposed experimental tests for the diquark model.

Abstract

The LHCb has discovered two new states with preferred $J^P$ quantum numbers $3/2^-$ and $5/2^+$ from $\Lambda_b$ decays. These new states can be interpreted as hidden charm pentaquarks. It has been argued that the main features of these pentaquarks can be described by diquark model. The diquark model predicts that the $3/2^-$ and $5/2^+$ are in two separate octet multiplets of flavor $SU(3)$ and there is also an additional decuplet pentaquark multiplet. Finding the states in these multiplets can provide crucial evidence for this model. The weak decays of b-baryon to a light meson and a pentaquark can have Cabibbo allowed and suppressed decay channels. We find that in the $SU(3)$ limit, for $U$-spin related decay modes the ratio of the decay rates of Cabibbo suppressed to Cabibbo allowed decay channels is given by $|V_{cd}|^2/|V_{cs}|^2$. There are also other testable relations for b-baryon weak decays into a pentaquark and a light pseudoscalar. These relations can be used as tests for the diquark model for pentaquark.