A Soft-Limit Theorem for the On-Shell Scattering Amplitudes Describing Processes Involving Massive Nambu-Goldstone Bosons

Abstract

In this thesis we consider systems where both Lorentz invariance and a continuous symmetry group G is explicitly broken by coupling a chemical potential µ to one of the generators Q of G. In such systems it is well known that there exist two different types of massive Goldstone bosons, denoted here as mNGBs and pNGBs. In this thesis we managed to prove that a scattering amplitude describing processes involving mNGBs vanish in the soft limit of the mNGB.