  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
$0.175\,\,\mathrm{GeV} < m_a < 4.78\,\,\mathrm{GeV}$.

High Energy Physics - Experiment