CP violation induced by neutral meson mixing interference

TL;DR

This paper introduces a new type of CP violation effect called double-mixing CP asymmetry, arising from interference in cascade decays involving two neutral meson mixings, with implications for precise CKM phase measurements.

Contribution

It proposes and analyzes the double-mixing CP asymmetry effect in cascade decays, enabling cleaner determination of CKM phases without strong interaction uncertainties.

Findings

Double-mixing CP asymmetry can be significant without strong phases.

The method allows direct extraction of weak and strong phases from experimental data.

Phenomenological examples demonstrate the practical applicability of the proposed effect.

Abstract

We propose a new kind of CP violation effect -- the double-mixing CP asymmetry -- in a type of cascade decays that involves at least two mixing neutral mesons in the decay chain. It is induced by the interference between different oscillation paths of the neutral mesons in the decay process. The double-mixing CP asymmetry is of critical importance for phenomenology, providing opportunities for clean determination of CKM phase angles free of uncertainties induced by the strong dynamics. To illustrate this point, we perform a phenomenological analysis on two examples: $B^0_s \to \rho^0 K \to \rho^0 (\pi^-\ell^+{\nu}_\ell)$ and $B^0 \to D^0 {K} \to D^0 (\pi^+\ell^-\bar{\nu}_\ell)$. Our results demonstrate that the double-mixing CP asymmetry can be numerically significant in the absence of strong phases, as shown by the former example. Additionally, the latter example showcases the direct extraction of weak and strong phases from data, without the need for theoretical inputs.