CPT VIOLATION IN STRING-MODIFIED QUANTUM MECHANICS AND THE NEUTRAL-KAON SYSTEM

Abstract

We argue that CPT is in general violated in a non-quantum-mechanical way in the effective low-energy theory derived from noncritical string theory, in which pure states evolve into mixed states in general. It is known that such a dynamical framework violates the strong form of CPT invariance. We relate CPT violation in the effective low-energy theory in our formalism to apparent world-sheet charge nonconservation induced by stringy monopoles corresponding to target-space black-hole configurations. We prove that energy is conserved on the average in this CPT-violating modification of quantum mechanics. The magnitude of the effective spontaneous violation of CPT may not be far from the present experimental sensitivity in the neutral-kaon system. We demonstrate that previously proposed phenomenological modifications to the quantum-mechanical description of the neutral-kaon system violate CPT, although in a different way from that assumed in analyses within conventional quantum mechanics. We sketch the way to constrain the novel CPT-violating parameters using available data on KL→2π, KS→ 3π0 and semileptonic KL,S decay asymmetries. Could non-quantum-field-theoretical and non-quantum-mechanical CPT violation usher in the long-awaited era of string phenomenology?