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Singlet charge 2/3 quark hiding the top quark: Fermilab Tevatron and CERN LEP implications

1995; American Physical Society; Volume: 51; Issue: 9 Linguagem: Inglês

10.1103/physrevd.51.5285

1538-4500

Wei Shu Hou, Hsuan‐Cheng Huang,

Particle Detector Development and Performance

If c and t quarks are strongly mixed with a weak singlet charge 2/3 quark, B(t\ensuremath{\rightarrow}l\ensuremath{\nu}+X) could be suppressed via the t\ensuremath{\rightarrow}${\mathit{cH}}^{0}$ mode; thereby, the top quark could still hide below ${\mathit{M}}_{\mathit{W}}$, whereas the heavy quark signal observed at the Fermilab Tevatron is due to the dominantly singlet quark Q. This may occur without affecting the small ${\mathit{m}}_{\mathit{c}}$ value. Demanding ${\mathit{m}}_{\mathit{Q}}$\ensuremath{\simeq}175 GeV and ${\mathit{m}}_{\mathit{t}}$\ensuremath{\lesssim}${\mathit{M}}_{\mathit{W}}$, we find that B(t\ensuremath{\rightarrow}l\ensuremath{\nu}+X) cannot be too suppressed. The heavy quark Q decays via W, H, and Z bosons. The latter can lead to b-tagged Z+4 jet events, while the strong c-Q mixing is reflected in a sizable Q\ensuremath{\rightarrow}sW fraction. Z\ensuremath{\rightarrow}tc\ifmmode\bar\else\textasciimacron\fi{} decay occurs at the tree level and may be at the ${10}^{\mathrm{\ensuremath{-}}3}$ order, leading to the signature of Z\ensuremath{\rightarrow}l\ensuremath{\nu}bc\ifmmode\bar\else\textasciimacron\fi{}, all isolated and with large ${\mathit{p}}_{\mathit{T}}$, at ${10}^{\mathrm{\ensuremath{-}}5}$ order.