Dark matter direct searches place very stringent constraints on the possible DM candidates proposed in extensions of the Standard Model. There are however models where these constraints are avoided. One of the simplest and most striking examples comes from a straightforward Higgs portal pseudoscalar DM model with a softly broken U(1) symmetry. In this model the tree-level DM-nucleon scattering cross section vanishes in the limit of zero momentum-transfer. Furthermore, adding doublets while keeping the pseudoscalar with the softly broken U(1) symmetry leads to the same result. We have calculated the exact cross section at the one-loop level in two of these scenarios, which is several orders of magnitude larger than the tree-level one. I will also compare these results with scalar DM models where the cancellation at tree-level does not occur. Finally I will present results for a simple model with a vector dark matter particle.
With support from FCT through project UIDB/00777/2020
