$\varepsilon'/\varepsilon$ in and beyond the Standard Model

TL;DR

This paper reviews the Standard Model prediction and potential New Physics contributions to the CP violation measure $oldsymbol{rac{oldsymbol{ ext{CP violation observable}}}{ ext{Standard Model}}}$, highlighting recent computations and theoretical frameworks.

Contribution

It introduces a master formula for BSM effects in $oldsymbol{rac{oldsymbol{ ext{CP violation observable}}}{ ext{Standard Model}}}$ and discusses a comprehensive approach including Dual QCD and SMEFT.

Findings

Deviations up to 2.9σ from experimental values depending on long-distance treatment.

New computations of hadronic matrix elements for NP operators.

A unified master formula for BSM contributions to $oldsymbol{rac{oldsymbol{ ext{CP violation observable}}}{ ext{Standard Model}}}$.

Abstract

Estimates of the CP violating observable $\varepsilon'/\varepsilon$ have gained some attention in the past few years. Depending on the long-distance treatment used, they exhibit up to $2.9\sigma$ deviation from the experimentally measured value. Such a deviation motivates the investigation of New Physics (NP) effects in the process $K\to\pi\pi$. In my talk I will review the Standard Model (SM) prediction for $\varepsilon'/\varepsilon$, with a special focus on the Dual QCD approach. On the NP side, I will discuss a recent computation of the hadronic matrix elements of NP operators. Furthermore a master formula for BSM effects in $\varepsilon'/\varepsilon$ is presented. Finally, a treatment of $\varepsilon'/\varepsilon$ using the SM effective theory (SMEFT) will be discussed together with possible correlations to other observables.