(1) CPPM, IN2P3, CNRS, Universite Mediteranee, Marseilles, France;(2) Institute for Theoretical and Experimental Physics, Bol'shaya Cheremushkinskaya ul. 25, Moscow, 117259, Russia;(3) ITEP, Moscow, Russia
Abstract:
The dependence of the Z-resonance shape on the location of the threshold of the N(bar N) production (N is the fourth-generation neutrino) is analyzed. The bounds on the existence of the fourth generation are derived from the comparison of the theoretical expression for the Z lineshape with the experimental data. The fourth generation is excluded at 95% C.L. for mN<46.7±0.2 GeV.