Probing <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi><mml:mi>t</mml:mi><mml:mover accent="true"><mml:mi>t</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover></mml:math> couplings using <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi></mml:math> boson polarization in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi><mml:mi>Z</mml:mi></mml:math> production at hadron colliders
Qing-Hong Cao, Bin Yan, C.–P. Yuan, Ya Zhang
Abstract
We propose to utilize the polarization information of the $Z$ bosons in $ZZ$ production, via the gluon-gluon fusion process $gg\ensuremath{\rightarrow}ZZ$, to probe the $Zt\overline{t}$ gauge coupling. The contribution of longitudinally polarized $Z$ bosons is sensitive to the axial-vector component (${a}_{t}$) of the $Zt\overline{t}$ coupling. We demonstrate that the angular distribution of the charged lepton from $Z$ boson decays serves well for measuring the polarization of $Z$ bosons and the determination of ${a}_{t}$. We show that $ZZ$ production via the $gg\ensuremath{\rightarrow}ZZ$ process complement to $Zt\overline{t}$ and $tZj$ productions in measuring the $Zt\overline{t}$ coupling at hadron colliders.