Confirmation of the Existence of the Σc++ and Λc+ Charmed Baryons and Observation of the Decay Λc+→Λπ+ and K¯0p

Abstract

In a broadband neutrino exposure of the Fermilab 15-ft bubble chamber, we observe the production of the ${{\Sigma }_c}^{++}\mathrm{}\left(2426\right)\mathrm{}$ charmed baryon followed by its decay to ${{\Lambda }_c}^{+}\mathrm{}\left(2260\right)\mathrm{}$ and ${\pi }^{+}$. We find the mass of the ${{\Lambda }_c}^{+}$ to be 2257±10 MeV and the $m\left({{\Sigma }_c}^{++}\right)-m\left({{\Lambda }_c}^{+}\right)$ mass difference to be 168±3 MeV. Previously unseen two-body decay modes of the ${{\Lambda }_c}^{+}\mathrm{}\left(2260\right)\mathrm{}$ are observed.