The way I understand scattering in classical physics is: it is underlying electromagnetic interaction plus the exclusive principle. So I had thought it would have no scattering nor interaction between dark matter particles, but it seems not a good guess, as people are all calculating dark matter particles' cross sections.
So what is under the hook for the scattering between electrically neutral particles? What exactly happening between fundamental particles scattering ? Are scattering consider some interaction? Or scattering is just some aftermath of the Exclusive principle?