Search for a fourth-generation quark more massive than the Z(0) boson in p(p)over-bar collisions at root s=1.8 TeV

We present the results of a search for pair production of a fourth-generation charge -1/3 quark (b') in root s = 1.8 TeV p (p) over bar collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b' --> bZ(0) and that the b' mass is greater than m(Z) + m(b). We studied the decay mode b'<(b')over bar> --> Z(0)Z(0)b (b) over bar where one Z(0) decays into e(+) e(-) or mu(+) mu(-) and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the sigma(p (p) over bar --> b'<(b')over bar>) x [B(b' --> bZ(0))](2) is established as a function of the b' mass. We exclude at 95% confidence level a b' quark with mass between 100 and 199 GeV/c(2) for B(b' --> bZ(0)) = 100%. RI Lancaster, Mark/C-1693-2008; Vucinic, Dejan/C-2406-2008; Nomerotski, Andrei/A-5169-2010; Prokoshin, Fedor/E-2795-2012; Chiarelli, Giorgio/E-8953-2012; Azzi, Patrizia/H-5404-2012