Journal of High Energy Physics

, 2016:83 | Cite as

A new look at the theory uncertainty of ϵ K

Open Access
Regular Article - Theoretical Physics

Abstract

The observable ϵ K is sensitive to flavor violation at some of the highest scales. While its experimental uncertainty is at the half percent level, the theoretical one is in the ballpark of 15%. We explore the nontrivial dependence of the theory prediction and uncertainty on various conventions, like the phase of the kaon fields. In particular, we show how such a rephasing allows to make the short-distance contribution of the box diagram with two charm quarks, η cc , purely real. Our results allow to slightly reduce the total theoretical uncertainty of ϵ K , while increasing the relative impact of the imaginary part of the long distance contribution, underlining the need to compute it reliably. We also give updated bounds on the new physics operators that contribute to ϵK.

Keywords

CP violation Kaon Physics 

Notes

Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

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Copyright information

© The Author(s) 2016

Authors and Affiliations

  1. 1.Ernest Orlando Lawrence Berkeley National LaboratoryUniversity of CaliforniaBerkeleyU.S.A.
  2. 2.LPTHE, CNRS, UMR 7589ParisFrance

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