Laser-assisted XUV few-photon double ionization of helium atoms: joint angular distributions

We have studied the multi-(XUV+IR)-photon double ionization of helium by solving the fully dimensional time-dependent Schr{\"o}dinger equation within a finite-element discrete-variable-representation scheme. We analyze the joint angular distributions for both equal and unequal energy sharing of the two emitted electrons for XUV-photon double ionization in the presence of a short IR pulse. For equal energy sharing, we find that the assisting IR pulse temporary promotes side-by-side emission and enables back-to-back emission. For unequal energy sharing case, we find enhanced back-to-back emission.