Energy Spectra and Energy Correlations in the Decay $H o ZZ o \mu^+\mu^-\mu^+\mu^-$

摘要

It is shown that in the sequential decay $H\to ZZ\to (f_1\bar{f_1})+(f_2\bar{f_2})$, the energy distribution of the final state particles providesa simple and powerful test of the $HZZ$ vertex. For a standard Higgs boson, theenergy spectrum of any final fermion, in the rest frame of $H$, is predicted tobe $d\Gamma /dx\sim 1+\beta^4-2(x-1)^2$, with $\beta = \sqrt{1-4m^2_Z/m^2_H}$and $1-\beta \le x=4E/m_H\le 1+\beta $. By contrast, the spectrum for apseudoscalar Higgs is $d\Gamma /dx \sim \beta^2+(x-1)^2$. There arecharacteristic energy correlations between $f_1$ and $f_2$ and between $f_1$and $\bar{f_2}$. These considerations are applied to the ``gold--plated''reaction $H\to ZZ\to \mu^+\mu^-\mu^+\mu^-$, including possible effects ofCP--violation in the $HZZ$ coupling. Our formalism also yields the energyspectra and correlations of leptons in the decay $H\to W^+W^-\to l^+\nu_ll^-\bar{\nu_l}$.