Owing to recent advances in laser technology, it has become important to investigate fundamental laser-assisted processes in very powerful laser fields. In the present work and within the framework of laser-assisted quantum electrodynamics, electron-proton scattering was considered in the presence of a strong electromagnetic field of circular polarization. First, we present a study of the process where we only take into account the relativistic dressing of the electron without the proton. Then, in order to explore the effect of the proton dressing, we fully consider the relativistic dressing of the electron and the proton together and describe them by using Dirac–Volkov functions. The analytical expression for the differential cross section (DCS) in both cases is derived at lowest-order of perturbation theory. As a result, the DCS is notably reduced by the laser field. It is found that the effect of proton dressing begins to appear at laser field strengths greater than or equal to 1010 V cm−1 and it therefore must be taken into account. The influence of the laser field strength and frequency on the DCS is reported. A comparison with the Mott scattering and the laser-free results is also included.

In this study, we have investigated the two-body hadronic decay of the charged kaon, $ K^{+}\rightarrow\pi^{+}+\pi^{0} $, in the presence of a laser field with circular polarization. We have derived, by analytical techniques, the laser-assisted decay width and the branching ratio of the charged kaon decay via the two-body hadronic channel. We have also taken into consideration the impressive results obtained for the laser-assisted charged kaon decay via the leptonic mode in order to understand more clearly the effect of the laser field on the quantities related to the charged kaon decay such as the decay width, the branching ratio and lifetime. A precise comparison of the ratios of hadronic to muonic decay in the presence of the laser field is made to show that the hadronic mode becomes slightly more important by increasing the laser field intensity.

The majority of studies and experiments performed at electron-positron colliders over the last two decades have focused on studying $W$ and $Z$ weak force-carrying bosons and accurately measuring all their properties, not only because they play an important role in establishing Standard Model theory and providing an accurate test of its predictions of particle interactions, but also because they are a unique tool for probing manifestations of the new physics beyond the standard model. Therefore, it would be particularly important to discuss some of the new phenomena and changes that can arise in these bosons when their decay occurs under an external electromagnetic field. In a recent paper, we investigated the laser effect on the final products of $Z$ boson decay and found that laser had an unprecedented effect on branching ratios. In this work 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. This work will pave the way for an upcoming one to study the hadronic decay of the $W^{-}$-boson and then explore the laser effect on its lifetime and branching ratios.

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In the absence and presence of a circularly polarized monochromatic electromagnetic pulse, we have analyzed the electron–nucleon scattering process, where the nucleon is assumed to be spinless with a spherical shape. We have provided the theoretical calculation of the differential cross section (DCS) by using the Dirac–Volkov formalism. This research paper aims to provide two comparisons: We first compare the DCS in the absence of the laser field with its corresponding laser-assisted DCS. A second comparison is made between the electron–proton and electron–neutron scattering processes to study the effect of the laser on both processes. The results obtained about the effect of the laser field on the DCS and the electric form factor have been discussed for both scattering processes. We have found that the DCS is reduced when the laser field is applied for both processes. In addition, the form factor is also decreased by raising the incident electron energy in electron–proton scattering, but it increases in electron–neutron scattering. Moreover, the form factors for both scattering situations are unchanged by raising the laser field strength up to [Formula: see text].