Which symmetries and restrictions does the Pauli-Villars regularisation scheme break/violate and which ones does it preserve? Consider: - Unitarity - Abelian gauge symmetry - Non-Abelian gauge symmetry - Supersymmetry I'm asking because I got confused after reading about it. Especially after reading/hearing statements that it breaks gauge symmetry for certain Non-abelian theories, that it violates unitarity in some cases, and that it breaks supersymmetry. etc. But I'm totally lost and I couldn't find one source that talks about the PV regularisation scheme describing all those situations. Can someone talk about the PV regularisation or refer me to a good reference that describes when and where the PV scheme is good or bad, and why and how!?