Search for an Axion-Like Particle in B Meson Decays

TL;DR

This paper reports a search for axion-like particles in B meson decays, setting new upper limits on their couplings and significantly improving constraints within a specific mass range, using data from the BABAR experiment.

Contribution

First search for ALPs in B meson decays with improved constraints on couplings, using BABAR data and analyzing the decay channel to photon pairs.

Findings

No significant ALP signal observed.

Established upper limits on ALP-electroweak couplings.

Constraints improved by several orders of magnitude.

Abstract

Axion-like particles (ALPs) are predicted in many extensions of the Standard Model, and their masses can naturally be well below the electroweak scale. In the presence of couplings to electroweak bosons, these particles could be emitted in flavor-changing $B$ meson decays. We report herein a search for an ALP, $a$, in the reaction $B^\pm\rightarrow K^\pm a$, $a\rightarrow\gamma\gamma$ using data collected by the BABAR experiment at SLAC. No significant signal is observed, and 90% confidence level upper limits on the ALP coupling to electroweak bosons are derived as a function of ALP mass, improving current constraints by several orders of magnitude in the range $0.175\,\,\mathrm{GeV} < m_a < 4.78\,\,\mathrm{GeV}$.