Coupled-channels analysis of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>α</mml:mi></mml:math> decay in strong electromagnetic fields

We investigate the influence of a monochromatic strong laser electromagnetic field on $\ensuremath{\alpha}$ clustering and emission, by analyzing the Fourier components of the time-dependent $\ensuremath{\alpha}$-core realistic potential in the Henneberger representation. It turns out that the resulting potential becomes deformed and the static component is by far dominant beyond the nuclear surface where the $\ensuremath{\alpha}$ cluster is formed, while higher Fourier terms are important in the internal region, where the $\ensuremath{\alpha}$-particle probability is hindered by the Pauli principle. This fact, combined with the observation that an $\ensuremath{\alpha}$ cluster lives much longer before its emission than the laser period, allows us the use of the stationary coupled channels approach in the system of coordinates given by the laser beam direction. We predict that the angular distribution of emitted $\ensuremath{\alpha}$ particles becomes anisotropic due to the deformation of the $\ensuremath{\alpha}$-core potential induced by the laser field, even for the spherical emitter $^{212}\mathrm{Po}$.