Search for resonance-enhanced $CP$ and angular asymmetries in the ${\mathrm{\Lambda }}_c^{+}\to p{\mu }^{+}{\mu }^{-}$ decay at LHCb

The first measurement of the $CP$ asymmetry of the decay rate ($A_{CP}$) and the $CP$ average ($\mathrm{\Sigma }{A}_{\text{FB}}$) and $CP$ asymmetry ($\mathrm{\Delta }{A}_{\text{FB}}$) of the forward-backward asymmetry in the muon system of ${\Lambda }_c^{+}\to p{\mu }^{+}{\mu }^{-}$ decays is reported. The measurement is performed using a data sample of proton-proton collisions, recorded by the LHCb experiment from 2016 to 2018 at a center-of-mass energy of 13$\text{ TeV}$, which corresponds to an integrated luminosity of 5.4${\text{ fb}}^{-1}$. The asymmetries are measured in two regions of dimuon mass near the $\phi$-meson mass peak. The dimuon-mass integrated results are \begin{align*} A_{CP} &= (-1.1 \pm 4.0 \pm 0.5)%,\ ΣA_{$\text{FB}$} &= (\phantom{-}3.9 \pm 4.0 \pm 0.6)%,\ ΔA_{$\text{FB}$} &= (\phantom{-}3.1 \pm 4.0 \pm 0.4)%, \end{align*} where the first uncertainty is statistical and the second systematic. The results are consistent with the conservation of $CP$ symmetry and the Standard Model expectations.