Precise $K^*(892) \to K\pi$ branching fractions

Abstract

Although discovered more than sixty years ago, direct measurement of the $K^*(892) \to K\pi$ branching fractions is a formidable challenge that has not been attempted. Typically they are assumed to obey the isospin limit in hundreds of particle data measurements. We show that an abundance of recent amplitude analyses and other data, however, enables recovery of the ratios $\mathcal{B}(K^{*+} \to K^+ \pi^0)/\mathcal{B}(K^{*+} \to K_S^0 \pi^+)$ and $4\mathcal{B}(K^{*0} \to K_S^0 \pi^0)/\mathcal{B}(K^{*0} \to K^+ \pi^-)$ at $\sim5\%$ precision.