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

TL;DR

This paper analyzes how identical lepton particles and their masses influence the decay processes of the Higgs boson into off-shell Z bosons decaying into tau pairs, highlighting effects near decay thresholds.

Contribution

It provides detailed calculations of decay rates and angular distributions considering lepton mass effects and particle identity, especially near off-shell decay thresholds.

Findings

Lepton mass effects are significant near decay thresholds.

Identical particle effects alter decay distributions compared to nonidentical cases.

Quantitative comparisons show measurable differences in decay rates and distributions.

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.