Brian Dolan (Maynooth University)
Title: Revisiting the CTP Theorem: the Quaternion Group and Discrete
Symmetries of the Lorentz Group
Abstract: Parity and time reversal, P and T, generate a discrete sub-group of the Lorentz group. Depending on the choice of phases in the definitions of P and T there is a family of possible sub-groups when acting on fermions, called di-cyclic groups (generalisations of the dihedral groups familiar from crystallography). When charge conjugation is included one special group is picked out, the eight component quaternion group.
We propose a two-slit experiment to measure the phase P when acting on fermions. In principle the T-parity of a neutral meson is observable and the CTP theorem dictates that T=CP.