Laser-induced selection of longitudinal $Z$ bosons in resonant $e^{+}{e}^{-}$ annihilation

Fengye Chen, Qingzheng Lv, Libin Fu

Longitudinal \(Z\)-boson production is strongly suppressed in collinear \(e^+e^-\) annihilation in vacuum due to current conservation and helicity selection. We show that this supp…