Search for a Fourth Generation Charge −1/3 Quark via Flavor Changing Neutral Current Decay

Le résumé fourni par la source

We report on a search for pair production of a fourth generation charge $\ensuremath{-}1/3$ quark ( ${b}^{\ensuremath{'}}$) in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8$ TeV by the D\O{} experiment at the Fermilab Tevatron using an integrated luminosity of 93 ${\mathrm{pb}}^{\ensuremath{-}1}$. Both ${b}^{\ensuremath{'}}$ quarks are assumed to decay via flavor changing neutral currents (FCNC). The search uses the signatures $\ensuremath{\gamma}+3$ jets $+\ensuremath{\mu}$-tag and $2\ensuremath{\gamma}+2$ jets. We see no significant excess of events over the expected background. We place an upper limit on the production cross section times branching fraction that is well below theoretical expectations for a ${b}^{\ensuremath{'}}$ decaying exclusively via FCNC for ${b}^{\ensuremath{'}}$ masses up to ${m}_{Z}{+m}_{b}$.

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