CPTtétel

CPT-tétel is a fundamental result in quantum field theory stating that any local, Lorentz-invariant quantum field theory with a stable vacuum and a Hermitian Hamiltonian is invariant under the combined CPT transformation, where C denotes charge conjugation, P parity transformation, and T time reversal. The theorem implies the existence of a CPT operator that is antiunitary, and it asserts that the theory’s S-matrix is unchanged under the application of CPT.

The precise statement is that, under the stated assumptions, the laws of physics do not distinguish a process from its CPT-reversed counterpart. Practically, this means that each particle has a CPT partner with identical mass and lifetime, and that certain quantum numbers change sign between particles and antiparticles (for example electric charge, baryon number, and lepton number). The relations imposed by CPT also constrain relations between decay amplitudes and cross sections for corresponding processes.

Historically, the CPT theorem was established in the 1950s within the framework of axiomatic or Wightman quantum field theory. Early contributions and rigorous proofs are associated with foundational work by researchers such as Lüders, Pauli, and later Jost, among others, who formalized the theorem under locality, Lorentz invariance, and the spectrum condition.

Experimentally, CPT invariance has been tested extensively. Comparisons of masses, lifetimes, and other properties of particles and antiparticles (such as protons vs antiprotons, kaons, and B mesons) show no violations within current precision. Searches for CPT violation remain an area of active study, particularly in contexts involving gravity, quantum gravity, or nonlocal theories, where deviations could signal new physics beyond standard quantum field theory.