Observation of the doubly Cabibbo-suppressed decay $\Xi_{c}^{+}\to p\phi$

The doubly Cabibbo-suppressed decay Ξ$_{c}^{+}$ → pϕ with ϕ → K$^{+}$K$^{−}$ is observed for the first time, with a statistical significance of more than fifteen standard deviations. The data sample used in this analysis corresponds to an integrated luminosity of 2 fb$^{−1}$ recorded with the LHCb detector in pp collisions at a centre-of-mass energy of 8 TeV. The ratio of branching fractions between the decay Ξ$_{c}^{+}$ → pϕ and the singly Cabibbo-suppressed decay Ξ$_{c}^{+}$ → pK$^{−}$π$^{+}$ is measured to be $ \frac{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p\phi \right)}{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p{K}^{-}{\pi}^{+}\right)}=\left(19.8\pm 0.7\pm 0.9\pm 0.2\right)\times {10}^{-3}, $