Evidence for the singly Cabibbo suppressed decay Λc+→pη and search for Λc+→pπ0

Le résumé fourni par la source

We study the singly Cabibbo suppressed decays ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p\ensuremath{\eta}$ and ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{0}$ using ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}^{\ensuremath{-}}$ pairs produced by ${e}^{+}{e}^{\ensuremath{-}}$ collisions at a center-of-mass energy of $\sqrt{s}=4.6\text{ }\text{ }\mathrm{GeV}$. The data sample was collected by the BESIII detector at the BEPCII collider and corresponds to an integrated luminosity of $567\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. We find the first evidence for the decay ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p\ensuremath{\eta}$ with a statistical significance of $4.2\ensuremath{\sigma}$ and measure its branching fraction to be $\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p\ensuremath{\eta})=(1.24\ifmmode\pm\else\textpm\fi{}0.28(\text{stat})\ifmmode\pm\else\textpm\fi{}0.10(\mathrm{syst}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. No significant ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{0}$ signal is observed. We set an upper limit on its branching fraction $\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{0})<2.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ at the 90% confidence level.

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