Evolution of the CPT Invariance into a Basic Postulate in Physics

TL;DR

This paper explores how CPT invariance evolved into a fundamental postulate in physics, linking space-time inversion with particle-antiparticle transformation across quantum theories, supported by historical and theoretical analysis.

Contribution

It proposes that CPT invariance naturally leads to space-time inversion being equivalent to particle-antiparticle transformation, tracing this idea from nonrelativistic quantum mechanics to quantum field theory.

Findings

CPT invariance implies space-time inversion relates particles and antiparticles.

Historical analysis connects EPR experiments with particle-antiparticle distinctions.

Discussion of Klein paradox in context of relativistic quantum equations.

Abstract

Einstein-Podolsky-Rosen's paper in 1935 is discussed in parallel with an EPR experiment on $K^0\bar{K}^0$ system in 1998, yielding a strong hint of distinction in both wave-function and operators between particle and antiparticle at the level of quantum mechanics (QM). Then it is proposed that the CPT invariance in particle physics leads naturally to a basic postulate that the (newly defined) space-time inversion (${\bf x}\to -{\bf x},t\to -t$) is equivalent to the transformation between particle and its antiparticle. The evolution of this postulate from nonrelativistic QM via relativistic QM till the quantum field theory is discussed in some detail. The Klein paradox for both Klein-Gordon equation and Dirac equation is also discussed. Keywords: CPT invariance, Antiparticle, Quantum mechanics, Quantum field theory