Electroweak Contributions to Indirect CP Violation in Neutral Kaons

by Zachary Polonsky (U. Zurich)

Monday 7 Oct 2024, 16:00 → 17:00 Europe/Berlin

ENC-D308

The parameter $\epsilon_K$ is an important measure of the imbalance between matter and antimatter in the neutral kaon ($K^0$ and $\bar K^0$) system, playing a critical role in searches for physics beyond the standard model as well as in fits of CKM matrix parameters. In experiments, $\epsilon_K$ has been measured to per-mil precision, but the theoretical calculation has been historically plagued by large uncertainties from the perturbative piece of the computation. In recent years, it was discovered that a simple reparameterization of the effective Hamiltonian dramatically reduces this source of uncertainty, making higher-order computations--particularly those from electroweak effects--worthwhile. In this talk, I will present next-to-leading order electroweak corrections to the perturbative calculation of $\epsilon_K$, including both the top quark and mixed charm-top contributions, and discuss the impact of different renormalization schemes and effective theory normalizations on the calculation.