Branching fraction measurements of $\eta$ and $\eta^\prime(958)$ anomalous decays
Roel Aaij, Ahmed Sameh Wagih Abdelmotteleb, Carlos Abellan Beteta, Fernando Jesus Abudinén et autres
Branching fractions of $\eta$ and $\eta'(958)$ anomalous decays are measured using $pp$ collision data at a center-of-mass energy of $\sqrt{s}=13\,\text{TeV}$ collected by the LHCb experiment and corresponding to an integrated luminosity of $5.4\,\text{fb}^{-1}$. The measured values and upper limits are \begin{align*} \mathcal{B}(\eta\to\mu^+\mu^-) …