Branching ratio measurements and isospin violation in B-meson decays

TL;DR

This paper examines the impact of isospin symmetry assumptions on B-meson decay measurements, providing a bias-free method to improve the accuracy of branching ratio and isospin violation analyses.

Contribution

It introduces a bias-free approach to determine B-meson production asymmetry, enhancing the precision of isospin violation studies in B-meson decays.

Findings

A new method to extract production asymmetry between charged and neutral B mesons.

Implications for more accurate branching ratio and isospin violation measurements.

Potential reduction of biases in current B-meson decay analyses.

Abstract

The approximate symmetry of the strong interactions under isospin transformations is among the most precise tools available to control hadronic matrix elements. It is crucial in extracting fundamental parameters, but also provides avenues for the search of phenomena beyond the Standard Model. The precision of the resulting predictions requires special care when determining the quantities they are to be tested with. Specifically, in the extraction of branching ratios often isospin symmetry is assumed at one point or another implicitly, implying a significant bias for precision analyses. We extract a bias-free value for the production asymmetry between charged and neutral $B$ meson pairs at $B$ factories and discuss its consequences for the determination of branching fractions generally, and isospin-violating observables like the rate asymmetries in B -> J/psi K or B -> K* gamma decays specifically.