Bargmann Invariants and Correlated Geometric CP-Violating Structures in Neutral Meson Systems

TL;DR

This paper explores how Bargmann invariants offer a geometric, rephasing-invariant framework to analyze CP violation in neutral meson systems, linking interference effects to fundamental weak phases.

Contribution

It introduces explicit expressions for higher-order invariants in meson systems and a new ratio that isolates correlated CP-violating structures, enhancing sensitivity to CP violation.

Findings

Derived explicit third- and fourth-order invariants in terms of mixing parameters and decay amplitudes.

Showed that geometric phases encode CP-sensitive interference effects and become trivial in CP-conserving limits.

Proposed a rephasing-invariant ratio to detect correlated CP-violating structures beyond independent decay channels.

Abstract

Bargmann invariants provide a rephasing-invariant description of phase relations among quantum states and offer a geometric perspective on interference phenomena. In this work, we investigate their role in neutral meson systems by constructing cyclic products involving the heavy and light mass eigenstates together with decay-projected states arising from correlated meson decays. Explicit expressions for third-order and fourth-order invariants are obtained in terms of mixing parameters and decay amplitudes. The analysis shows that the associated geometric phases encode CP-sensitive interference effects between meson-antimeson mixing and decay amplitudes and become trivial in the CP-conserving limit. Expressing the decay amplitudes in terms of CKM matrix elements reveals quartic combinations with analogous rephasing-invariant weak-phase structure to that of the Jarlskog invariant. We further introduce a rephasing-invariant ratio constructed from third- and fourth-order Bargmann invariants, which isolates correlated CP-violating structures that cannot, in general, be factorized into independent decay-channel contributions and can enhance sensitivity to small deviations from CP symmetry. The invariants can also be related to parameters governing time-dependent CP asymmetries in neutral meson decays, thereby providing a geometric interpretation of observable CP-violating interference effects.