Observation of the doubly Cabibbo-suppressed decay ${\mathrm{\Xi }}_c^{+}\to p\varphi$

The doubly Cabibbo-suppressed decay ${\mathrm{\Xi }}_c^{+}\to p\varphi$ with $\phi\to K^{+}K^{-}$ 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 ${\mathrm{\Xi }}_c^{+}\to p\varphi$ and the singly Cabibbo-suppressed decay ${\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+}$ is measured to be \begin{equation*} \frac{$\mathcal{B}$(\Xi_{c}^{+}\to p\phi)}{$\mathcal{B}$(\Xi_{c}^{+}\to pK^{-}\pi^{+})} = (19.8 \pm 0.7 \pm 0.9 \pm 0.2) \times 10^{-3}, \end{equation*} where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the $\varphi \to K^{+}{K}^{-}$ branching fraction.