Observation of the Heavy Baryons Σb and Σb*

Le résumé fourni par la source

We report an observation of new bottom baryons produced in $p\overline{p}$ collisions at the Tevatron. Using $1.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected by the CDF II detector, we observe four ${\ensuremath{\Lambda}}_{b}^{0}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ resonances in the fully reconstructed decay mode ${\ensuremath{\Lambda}}_{b}^{0}\ensuremath{\rightarrow}{\ensuremath{\Lambda}}_{c}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, where ${\ensuremath{\Lambda}}_{c}^{+}\ensuremath{\rightarrow}p{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$. We interpret these states as the ${\ensuremath{\Sigma}}_{b}^{(*)\ifmmode\pm\else\textpm\fi{}}$ baryons and measure the following masses: ${m}_{{\ensuremath{\Sigma}}_{b}^{+}}={5807.8}_{\ensuremath{-}2.2}^{+2.0}(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}1.7(\mathrm{syst}.)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, ${m}_{{\ensuremath{\Sigma}}_{b}^{\ensuremath{-}}}=5815.2\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}1.7(\mathrm{syst}.)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, and $m({\ensuremath{\Sigma}}_{b}^{*})\ensuremath{-}m({\ensuremath{\Sigma}}_{b})={21.2}_{\ensuremath{-}1.9}^{+2.0}(\mathrm{stat}.{)}_{\ensuremath{-}0.3}^{+0.4}(\mathrm{syst}.)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.