Search for a fourth generation b'-quark at LEP-II at sqrt{s}=196-209 GeV

12 pages, 12 figures.-- ISI Article Identifier: 000245853100001.-- El Pdf del artículo es la versión pre-print: http://arxiv.org/pdf/0704.0594.-- DELPHI Collaboration: et al.A search for the pair production of fourth generation b'-quarks was performed using data taken by the DELPHI detector at LEP-II. The analysed data were collected at centre-of-mass energies ranging from 196 to 209 GeV, corresponding to an integrated luminosity of 420 pb(-1). No evidence for a signal was found. Upper limits on BR(b'-> bZ) and BR(b'-> bZ) were obtained for b' masses ranging from 96 to 103 GeV/c^2 stop. These limits, together with the theoretical branching ratios predicted by a sequential four generations model, were used to constrain the value of R_CKM=vertical bar V_cb' / V_tb' V_tb vertical bar, where V_cb', V_tb' and V_tb are elements of the extended CKM matrix.Peer reviewe

Search for a fourth generation b-prime-quark at LEP-II at s**(1/2) = 196-GeV - 209-GeV.

A search for the pair production of fourth generation b’-quarks was performed using data taken by the DELPHI detector at LEP-II. The analysed data were collected at centre-of-mass energies ranging from 196 to 209 GeV, corresponding to an integrated luminosity of 420 pb-1. No evidence for a signal was found. Upper limits on BR(b’→bZ) and BR(b’→cW) were obtained for b’ masses ranging from 96 to 103 GeV/c 2. These limits, together with the theoretical branching ratios predicted by a sequential four generations model, were used to constrain the value of , where Vcb′, Vtb′ and Vtb are elements of the extended CKM matrix