Symmetry protection of a small mass
= Symmetry protection of a small mass
A small mass is technically protected when its vanishing restores a symmetry that restricts the corresponding quantum corrections. <Gauge protection of a vector mass>, <chiral protection of a fermion mass>, and <supersymmetry> protection of scalar masses use different symmetry constraints. This is a radiative-stability statement, not a proof that all small numerical parameters require such protection.