CP as a Symmetry of Symmetries

5th Symposium on Prospects in the Physics of Discrete Symmetries

Trautner, Andreas^1

Bethe Center for Theoretical Physics und Physikalisches, Institut der Universität Bonn, Nussallee 12, Bonn

53115, Germany^1

关键词: Automorphisms;    Charge conjugation;    Complex conjugations;    Gauge symmetries;    Physical theory;    Space time symmetry;    The standard model;    Toy models;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/873/1/012037/pdf
DOI  :  10.1088/1742-6596/873/1/012037

来源: IOP

【 摘 要 】

It is explained that the Standard Model combined charge conjugation and parity transformation (CP) is a simultaneous complex conjugation outer automorphism transformation of gauge and space-time symmetries. Simple examples are given for the general concept of outer automorphisms ("symmetries of symmetries"), as well as for their possible actions on physical theories. It is highlighted that complex conjugation outer automorphisms do not, in general, exist for all symmetries. Examples are given for cases in which the physical CP transformation is violated as a consequence of requiring another symmetry. A toy model is illustrated in which CP is spontaneously violated in the broken phase of a continuous gauge symmetry, while an unbroken outer automorphism protects the topological vacuum angle at θ = 0.