Undergrad How Does CP Violation Relate to Matter-Antimatter Asymmetry in the Universe?

[Malamala]

Hello! I don't know much about this topic so I apologize if my question is not very clear. I understand that one of the conditions required to explain the matter-antimatter asymmetry in the universe is to have CP (charge-parity) violation. We have CP violation in the standard model (SM), in the CKM matrix observed in Kaon (or B, D mesons) system, but the CP violation induced there is not enough to explain the observed matter-antimatter asymmetry. So now there are BSM (beyond SM) theories which are assumed to induce much higher CP violation effects, that would explain the asymmetry. For example, the electron electric dipole moment (EDM) induced by CKM is too small to be observed experimentally, but the EDM that could be induced by BSM theories might be orders of magnitudes higher and hence observable. I am not sure I understand, how come we haven't observed this much higher effects, given that we already observed the ones from the CKM matrix? If we can have an observable enhanced so much (the EDM) how come we don't see that effect in the kaon oscillation? Basically, if we have much higher CP violating effects BSM than in the SM, how come we didn't see these first? Thank you!

 

[mfb]

The relative strength of CP violation in a specific observable depends on that observable. If you look at kaon mixing you see SM CP violation - BSM effects are small. If you look at the electron EDM then the SM contribution is really tiny. BSM effects don't have to be larger - but they can be, so we look for them.
This is a general pattern: If you want to search for BSM look in places where SM processes are very rare, or at least really well-understood: Rare decays like $B_{(s)} \to \mu \mu$, searches for lepton flavor violation in decays where electrons and muons should be equally likely (with tiny theoretical uncertainties), and so on.