Observation of the doubly Cabibbo-suppressed decay Ξc+ → pϕ

The doubly Cabibbo-suppressed decay Ξc+ → 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 Ξc+ → pϕ and the singly Cabibbo-suppressed decay Ξc+ → pK−π+ is measured to be ℬΞc+→pϕℬΞc+→pK−π+=19.8±0.7±0.9±0.2×10−3,\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \frac{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p\phi \right)}{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p{K}^{-}{\pi}^{+}\right)}=\left(19.8\pm 0.7\pm 0.9\pm 0.2\right)\times {10}^{-3}, $$\end{document} where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the ϕ → K+K− branching fraction.