Study of heavy quark conserving weak decays in the quark model

TL;DR

This paper uses a constituent quark model to analyze heavy quark conserving weak decays of $\\Xi_c$ and $\\Xi_b$ baryons, highlighting the role of heavy quark symmetry and predicting branching ratios consistent with recent experimental data.

Contribution

It provides a detailed theoretical analysis of heavy quark conserving weak decays using the quark model, emphasizing the importance of heavy quark symmetry and predicting decay branching ratios.

Findings

Pole dominance explains large $\\Xi_c^0\to\Lambda_c\pi^-$ branching ratio.

Decays of $\\Xi_b$ are primarily parity-violating due to heavy quark symmetry.

Predicted branching ratios for $\\Xi_c^+\to\Lambda_c\pi^0$ and $\\Xi_b^0\to\Lambda_b\pi^0$.

Abstract

Within the framework of a constituent quark model, we investigate the heavy quark conserving weak decays of $\Xi_c$ and $\Xi_b$. This process involves elementary transitions of $us\to du$ or $s\to ud \bar u$ with the heavy quark as a spectator, while for the charmed baryon in the initial state it can also occur via $cs\to dc$ to conserve the heavy quark flavor in the weak decays. It shows that the heavy quark symmetry (HQS) plays an essential role in the processes where the heavy quark acts as a spectator. For the $\Xi_c$ decays, the dominance of the pole terms in the parity-conserving transitions is evident. This can naturally explain the sizeable branching ratio for $\Xi_c^0\to\Lambda_c\pi^-$ as recently reported by LHCb. The same mechanism predicts a large branching ratio for $\Xi_c^+\to\Lambda_c\pi^0$. In contrast, the decays of $\Xi_b$ will only go through the parity-violating processes because of the HQS. In addition, the branching ratios of the $\Xi_c^+\to \Lambda_c \pi^0$ and $\Xi_b^0\to \Lambda_b \pi^0$ processes are also predicted for the further experimental measurement.