Exploring Background Contributions in $H \to Z \gamma$ Decay
Pre-published on:
January 14, 2026
Published on:
—
Abstract
The rare decay $H \to Z\gamma$ has been investigated by both the ATLAS and CMS Collaborations, with each reporting an excess in Run~2 in 2023 characterized by $\mu = 2.2 \pm 0.7$. This anomaly was initially attributed to possible modifications of the $HZ\gamma$ vertex. However, because the $H \to Z\gamma$ signal is reconstructed via the $H \to \ell\ell\gamma$ channel, background effects -particularly those from processes that mimic the same final state - may have been underestimated. In this work, we re-examine these backgrounds in detail and propose that the observed excess could be explained by an additional BSM-induced contribution. We present both an effective field theory framework and a UV-complete model that provide the necessary rates and a consistent interpretation of the data. The proposed model reproduces the newest ATLAS result, $\mu = 1.3^{+0.6}_{-0.5}$, obtained using a narrower dilepton invariant-mass window.
DOI: https://doi.org/10.22323/1.485.0379
How to cite
Metadata are provided both in
article format (very
similar to INSPIRE)
as this helps creating very compact bibliographies which
can be beneficial to authors and readers, and in
proceeding format which
is more detailed and complete.