arXiv subjects
Publications and source records attributed to H. Uibo.
A future e+e- Linear Collider has a large physics potential for the discovery of new physics beyond the Standard Model and precision studies of the Standard Model itself. It is well suited to complement and extend the physics program of the LHC concerning the precise determination of the underlying theory. The use of polarized beams at a LC will be one of the decisive tools.
We consider the equilibration of the 'wrong--helicity' Dirac neutrino states $ν_{+}$ and $\overlineν_{-}$ in the early Universe via weak interactions and calculate carefully the thermally averaged production rate, taking into account all the relevant scattering and decay processes. Requiring that the production rate is less than the Hubble parameter at the onset of QCD phase transition so that the nucleosynthesis predictions are not contradicted, we find for $T_{\rm{QCD}}\simeq 200$ MeV the upper limits $m_{ν_τ}\lsim 740$ keV and $m_{ν_μ}\lsim 480$ keV.