$Z$-boson production via the weak process $e^+e^- \to \mu^+\mu^-$ in the presence of a circularly polarized laser field

TL;DR

This paper theoretically investigates the production of Z-bosons in electron-positron collisions within a circularly polarized laser field, revealing significant effects on cross sections and validating the Breit-Wigner approach under intense laser conditions.

Contribution

It demonstrates how a strong circularly polarized laser field influences Z-boson production cross sections and confirms the validity of the Breit-Wigner formula in laser-assisted processes.

Findings

Laser field decreases Z-boson cross section by orders of magnitude.

Breit-Wigner formula remains valid with laser dressing.

Laser field significantly affects total cross section at high intensities.

Abstract

In the centre of mass frame, we have studied theoretically the $Z$-boson resonant production in the presence of an intense laser field via the weak process $e^+e^- \to \mu^+\mu^-$. Dressing the incident particles by a Circularly Polarized laser field (CP-laser field), at the first step, shows that for a given laser field's parameters, the $Z$- boson cross section decreases by several orders of magnitude. We have compared the the Total Cross Section (TCS) obtained by using the scattering matrix method with that given by the Breit-Wigner approach in the presence of a CP-laser field and the results are found to be very consistent. This result indicates that Breit-Wigner formula is valid not only for the laser-free process but also in the presence of a CP-laser field. The dependence of the laser-assisted differential cross section on the Centre of Mass Energy (CME) for different scattering angles proves that it reaches its maximum for small and high scattering angles. At the next step and by dressing both incident and scattered particles, we have shown that the CP-laser field largely affects the TCS, especially when its strength reaches $10^{9}\,V.cm^{-1}$. This result confirms that obtained for the elastic electron-proton scattering in the presence of a CP-laser field [I. Dahiri et al., arXiv:2102.00722v1]. It is interpreted by the fact that heavy interacting particles require high laser field's intensity to affect the collision's cross section.