New phenomena in laser-assisted leptonic decays of the negatively charged boson $W^{-}$

TL;DR

This paper theoretically investigates how a circularly polarized laser field influences the leptonic decay of the W- boson within the Standard Model, revealing significant effects on decay rates and potential new decay channels.

Contribution

It introduces a detailed theoretical analysis of laser effects on W- boson leptonic decay using exact relativistic wave functions, highlighting the conditions under which decay rates are altered.

Findings

Laser significantly reduces W- boson decay probability.

Decay rate equals laser-free rate only when Kroll-Watson sum rule holds.

Laser effects can be interpreted via quantum Zeno effect or new decay channels.

Abstract

In this paper and within the standard Glashow-Weinberg-Salam model of electroweak interactions, we study theoretically the leptonic decay of the $W^{-}$-boson $(W^{-}\rightarrow \ell^{-}\bar{\nu}_{\ell})$ in the presence of a circularly polarized electromagnetic field and we examine the laser effect, in terms of its field strength and frequency, on the leptonic decay rate and the phenomenon of multiphoton processes. The calculations are carried out using the exact relativistic wave functions of charged particles in an electromagnetic field. It was found that the laser significantly contributed to reducing the probability of $W^{-}$-boson decay. We show that the laser-assisted decay rate is equal to the laser-free one only when the famous Kroll-Watson sum rule is fulfilled. The notable effect of the laser on the leptonic decay rate was reasonably interpreted by the well-known quantum Zeno effect or by the opening of channels other than leptonic ones to decay. We hope that this article paved the way for an upcoming paper to study the hadronic decay of the $W^{-}$-boson and then explore the laser effect on its lifetime and branching ratios.