Precision tests ofCPTsymmetry and quantum mechanics in the neutral kaon system

We present a systematic phenomenological analysis of the tests of CPT symmetry that are possible within an open quantum-mechanical description of the neutral kaon system that is motivated by arguments based on quantum gravity and string theory. We develop a perturbative expansion in terms of the three small CPT-violating parameters admitted in this description, and provide expressions for a complete set of K→2π, 3π, and πlν decay observables to second order in these small parameters, and contrast this formalism with CPT violation within conventional quantum mechanics. We also illustrate the new tests of CPT symmetry and quantum mechanics that are possible in the open quantum-mechanical formalism using a regenerator. Indications are that experimental data from the CPLEAR and previous experiments could be used to establish upper bounds on the CPT-violating parameters that are of order ${10}^{\mathrm{-}19}$ GeV, approaching the order of magnitude that may be attainable in quantum theories of gravity. © 1996 The American Physical Society.