Speaker
Description
We show how the $Z$ boson polarization can be used to study the $ZH$ production at future $e^+e^-$ colliders and at the LHC. We calculate the 8 independent polarization parameters of the spin-1 $Z$ boson which are sensitive to anomalous gauge-Higgs couplings, using $Z$ spin density matrix. By constructing angular asymmetries from the $Z$ boson decay leptons, which are related to the polarization observables, we constrain the anomalous $ZZH$ couplings. Taking into account possible longitudinal beam polarizations at two different center of mass energies, we find that oppositely polarized beams at 500 GeV c.m. energy provides tighter bounds on the couplings than the same sign polarized and unpolarized beams. We find that most of the $1\sigma$ limits are of the order of a few times
$10^{-3}$ for 14 TeV LHC with integrated luminosity of
1000 $\text{fb}^{-1}$ and for 500 GeV $e^+e^-$ colliders with oppositely polarized beams.
