Study on ${\nu }_{\mu }$, ${\nu }_{\tau }$ Decays and CP-Non Invariance at Early Epoch of the Universe

Abstract

We study the ${\nu }_{\mu }$ and ${\nu }_{\tau }$ decays in the early epoch of the universe. If $m_{{\nu }_{\tau }}>2m_e$, there would be a CP asymmetry between ${\nu }_{\tau }\to e^{+}+e^{-}+{\nu }_e$ and ${\bar{\nu }}_{\tau }\to e^{+}+e^{-}+{\bar{\nu }}_e$. The resultant CP non-invariance is a function of temperature and density and can reach $10^{-7}$ for a reasonable temperature range, but it is noticed that if $m_{{\nu }_{\tau }}>2m_{\mu }\sim 200$ MeV, the CP non-invariance can be much larger.

14 pages(LaTeX), uuencode, 2 figures(1 PS file)