= Discrete symmetry in quantum field theory
A discrete symmetry maps fields and states to new configurations through transformations not continuously connected to the identity within the stated symmetry group. Important examples are <charge conjugation>, <parity symmetry in quantum field theory> and <time-reversal symmetry>.
Testing such a symmetry requires transforming the fields, their arguments and all relevant interaction terms. A free kinetic term may be invariant even when an interaction is not. A <weak charged current>, for example, distinguishes left- and right-chiral matter and violates parity. Products such as <CP symmetry> can behave differently from their factors. The <CPT theorem> supplies a combined symmetry under its relativistic locality and quantum-theory hypotheses; it does not assert separate conservation of each factor.
Back to article page
