##### Search for a fourth generation b'-quark at LEP-II at $\sqrt{s}$ = 200 - 209 GeV

Authors: S Andringa, N. Castro, M. Espirito-Santo, P Gonçalves, O. Oliveira, A. Onofre, M. Pimenta, B. Tomé, F. Veloso

Ref.: DELPHI 2002-063 CONF 597 (2002)

Abstract: A search for the double production of a fourth generation b'-quark was performed using data taken by the DELPHI detector at LEP-II. The analysed data were collected at centre-of-mass energies ranging from 200 to 209 GeV, with an integrated luminosity of about 344 pb$^{-1}$. No evidence for a signal was found. A preliminary upper limit on $\sigma_{e^{+}e^{-} \rightarrow b'b'} \times ( BR_{b' \rigtharrow b Z^0} )^2$ of 0.2 pb was obtained at 95 \% confidence level of $m_{b'}$ = 100 GeV.