Doubly CKM-suppressed corrections to CP asymmetries in $B^0 \to J/\psi K^0$

TL;DR

This paper calculates an upper bound of about 0.1% on rescattering corrections to CP asymmetries in B0 decays, refining previous estimates of potential long-distance effects.

Contribution

The study provides a new, more precise upper bound on rescattering corrections to CP asymmetries in B0 to J/psi K0 decays, using measured branching ratios.

Findings

Rescattering corrections are bounded at around 10^-3.

Long-distance effects are smaller than several percent.

The results constrain theoretical uncertainties in CP asymmetry measurements.

Abstract

A doubly CKM-suppressed amplitude in $B^0\to J/\psi K_S$ leads to corrections in CP asymmetries $S = \sin 2\beta, C=0$, which may be enhanced by long-distance rescattering. It has been suggested that this enhancement may lead to several percent corrections. We calculate an upper bound of order $10^{-3}$ on rescattering corrections using measured branching ratios for charmless $|\Delta S|=1$ $B^0$ decays.