Singlet charge 2\/3 quark hiding the top

Article
Report number	hep-ph/9409227 ; NTUTH-94-18 ; NTUTH-94-18
Title	Singlet charge 2\/3 quark hiding the top : Tevatron and LEP implications
Author(s)	Hou, Wei-Shu (Taiwan, Natl. Taiwan U. ; CERN) ; Huang, Hsuan-Cheng (Taiwan, Natl. Taiwan U.)
Publication	1995
Imprint	5 Sep 1994
Number of pages	13
In:	Phys. Rev. D 51 (1995) 5285-5288
DOI	10.1103/PhysRevD.51.5285
Subject category	Particle Physics - Phenomenology
Abstract	If $c$ and $t$ quarks are strongly mixed with a weak singlet charge $2/3$ quark, $BR(t\to \ell\nu + X)$ could be suppressed via the $t\to cH 0$ mode, thereby the top quark could still hide below $M_W$, whereas the heavy quark signal observed at the Tevatron is due to the dominantly singlet quark $Q$. This may occur without affecting the small $m_c$ value. Demanding $m_Q \simeq 175$ GeV and $m_t \ltap M_W$, we find that $BR(t\to \ell\nu + X)$ 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 sizable $Q\to sW$ fraction. $Z\to t\bar c$ decay occurs at tree level and may be at the $10 {-3}$ order, leading to the signature of $Z\to \ell\nu b\bar c$, all isolated and with large $p_T$, at $10 {-5}$ order.