Generation of isospin sum rules in heavy hadron weak decays

TL;DR

This paper introduces a systematic method to generate isospin sum rules for heavy hadron weak decays, enhancing understanding of isospin symmetry in charm and bottom hadron processes.

Contribution

It presents a new approach to derive isospin sum rules without Wigner-Eckhart invariants, applicable to $c$- and $b$-hadron weak decays.

Findings

Systematic generation of isospin sum rules for heavy hadron decays.

Application to $D$ and $B$ meson nonleptonic decays.

Extension to $V$- and $U$-spin sum rules.

Abstract

Isospin symmetry is the most precise flavor symmetry. In this work, we propose an approach to generate isospin sum rules for heavy hadron decays without the Wigner-Eckhart invariants. The effective Hamiltonian of heavy quark weak decay is fully invariant under a series of isospin lowering operators $I_-^n$ and then the isospin sum rules can be generated through several master formulas. It provides a systematic way to study the isospin symmetry of $c$- and $b$-hadron weak decays. The theoretical framework of this approach is presented in detail with the nonleptonic decays of $D$ and $B$ mesons as examples. In addition, the $V$-/$U$-spin sum rules are derived in a similar algorithm by replacing $I_-^n$ with $V_-^n$/$U_-^n$.