CP violation with an unbroken CP transformation
Published Web Locationhttps://doi.org/10.1007/jhep02(2017)103
A CP conserving SU(3) gauge theory is spontaneously broken to T7 by the vacuum expectation value (VEV) of a 15-plet. Even though the SU(3)-CP transformation is not broken by the VEV, the theory exhibits physical CP violation in the broken phase. This is because the SU(3)-CP transformation corresponds to the unique order-two outer automorphism of T7, which is not a physical CP transformation for the T7 states, and there is no other possible CP transformation. We explicitly demonstrate that CP is violated by calculating a CP odd decay asymmetry in the broken phase. This scenario provides us with a natural protection for topological vacuum terms, ensuring that θGμνG˜ μν is absent even though CP is violated for the physical states of the model.