Alpha-nucleus optical potentials from chiral EFT $NN$ interactions.

We present a determination of optical potentials for $^4$He-target collisions using the double-folding method based on chiral effective field theory nucleon-nucleon interactions at next-to-next-to-leading order combined with state-of-the-art nucleonic densities. The imaginary part of the optical potentials is obtained applying dispersion relations. With these potentials, we compute the elastic scattering of $^4$He off various targets, from $^4$He to $^{120}$Sn. We study the sensitivity of our predicted cross sections to the choice of nucleon-nucleon interactions and nuclear densities. Very good agreement is obtained with existing elastic-scattering data for $^4$He energies between 100 and 400 MeV without any fitting parameter.