Topic 18 – C,P and CP Pre‐Lecture Reading/Post‐Lecture Summary We will begin with a few residual issues from the Higgs mechanism including a better analogy for how nontrivial backgrounds influence fluctuations, how the Goldstone boson is "eaten" by the gauge field (relevant for the HW) and further discussion on the prevalence of spontaneously broken symmetry. Then... We have spent much of our time focusing on continuous symmetries that are important for the Standard Model. However there are a few discrete symmetries which also play important roles. We will begin an analysis of these discrete symmetries by discussing in detail parity. While this was originally presumed to be a good symmetry of the Standard Model, experimental evidence has shown that in fact it is violated by the weak interactions in particular. We will review the experiments which revealed this. Then you will leave and be somewhat dissapointed.