Leptophobic dark photon interpretation of the $\eta^{\left(\prime\right)}\rightarrow\pi^0\left(\eta\right)\gamma\gamma$ puzzle

TL;DR

This paper investigates the decay processes of eta mesons to identify signs of a leptophobic dark photon, proposing a novel method to constrain its properties through decay mismatches rather than traditional bump searches.

Contribution

It introduces a leptophobic dark photon model to resolve decay discrepancies and suggests a new approach for constraining dark photon parameters using decay mismatches.

Findings

A leptophobic dark photon can explain decay discrepancies.

Proposed decay mismatch analysis as a new constraint method.

Consistent decay descriptions achieved with specific dark photon parameters.

Abstract

The decays of $\eta$ and $\eta^\prime$ mesons provide unique opportunities for testing the properties of low energy Quantum Chromodynamics and for the search of new physics beyond the Standard Model. However, recent experimental results on the rare decays of $\eta^{\left(\prime\right)}\rightarrow\pi^0\left(\eta\right)\gamma\gamma$ cannot be self-consistently described by the combination of the Vector Meson Dominance and Linear Sigma Model employing the same set of parameters. We show that this tension can be attributed to the presence of a leptophobic dark photon $\mathcal{B}$, and find representative values of the parameters which provide consistent description of these three decays, simultaneously. Unlike existing strategies of Dalitz analysis searching for the bump at $m_\mathcal{B}$, we propose the usage of mismatch between these decays to constrain the parameters of the hypothetical dark photon.