Identical particle and lepton mass effects in the decay $H\to Z^\ast(\to\tau^+\tau^-)+Z^\ast(\to\tau^+\tau^-)$

Abstract

We consider identical particle and lepton mass effects in the cascade decay $H\to Z^\ast(\to\tau^+\tau^-)+Z^\ast(\to\tau^+\tau^-)$. Since the scale of the problem is set by the off-shellness $p_a^2$ and $p_b^2$ of the respective gauge bosons in the limits ($4m_\tau^2\le p_a^2,p_b^2\le (m_H-2m_\tau)^2$) and not by $m_H^2$, lepton mass effects are nonnegligible in particular close to the threshold of the off-shell decays. We calculate the rates and single angle decay distributions and compare them with the corresponding rates and single angle decay distributions for the nonidentical particle decays $H\to Z^\ast(\to e^+e^-)+Z^\ast(\to\mu^+\mu^-)$ involving negligible lepton masses.