A new look at the theory uncertainty of ϵ K
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 shortdistance 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 ϵ _{K} .
 Authors:

^{[1]};
^{[2]}
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Centre National de la Recherche Scientifique (CNRS), AnnecyleVieux (France). Lab. D' AnnecyleVieux de Physique Theorique (LAPth)
 Publication Date:
 Grant/Contract Number:
 AC0205CH11231
 Type:
 Accepted Manuscript
 Journal Name:
 Journal of High Energy Physics (Online)
 Additional Journal Information:
 Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2016; Journal Issue: 9; Journal ID: ISSN 10298479
 Publisher:
 Springer Berlin
 Research Org:
 Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
 Sponsoring Org:
 USDOE Office of Science (SC), High Energy Physics (HEP) (SC25)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CP violation; kaon physics
 OSTI Identifier:
 1377439
Ligeti, Z., and Sala, F.. A new look at the theory uncertainty of ϵ K. United States: N. p.,
Web. doi:10.1007/JHEP09(2016)083.
Ligeti, Z., & Sala, F.. A new look at the theory uncertainty of ϵ K. United States. doi:10.1007/JHEP09(2016)083.
Ligeti, Z., and Sala, F.. 2016.
"A new look at the theory uncertainty of ϵ K". United States.
doi:10.1007/JHEP09(2016)083. https://www.osti.gov/servlets/purl/1377439.
@article{osti_1377439,
title = {A new look at the theory uncertainty of ϵ K},
author = {Ligeti, Z. and Sala, F.},
abstractNote = {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 shortdistance 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 ϵ K .},
doi = {10.1007/JHEP09(2016)083},
journal = {Journal of High Energy Physics (Online)},
number = 9,
volume = 2016,
place = {United States},
year = {2016},
month = {9}
}