English

Updated evaluation of $\varepsilon_K$ in the Standard Model with lattice QCD inputs

High Energy Physics - Lattice 2018-11-21 v3 High Energy Physics - Phenomenology

Abstract

We report a strong tension in εK\varepsilon_K at the 4σ4\sigma level between the experimental value and the theoretical value calculated directly from the standard model using lattice QCD inputs such as B^K\hat{B}_K, Vcb|V_{cb}|, Vus|V_{us}|, ξ0\xi_0, ξ2\xi_2, ξLD\xi_\text{LD}, FKF_K, and mcm_c. The standard model with lattice QCD inputs describes only 70% of the experimental value of εK\varepsilon_K, and does not explain its remaining 30%. We also find that this tension disappears when we use the inclusive value of Vcb|V_{cb}| (results of the heavy quark expansion based on QCD sum rules) to determine εK\varepsilon_K. This tension is highly correlated with the present discrepancy between the exclusive and inclusive values of Vcb|V_{cb}|. In order to resolve, in part, the issue with Vcb|V_{cb}|, it would be highly desirable to have a comprehensive re-analysis over the entire set of experimental data on the BˉDνˉ\bar{B} \to D^* \ell \bar{\nu} decays using an alternative parametrization of the form factors, such as the BGL parametrization, and a comparison with results of the CLN method.

Keywords

Cite

@article{arxiv.1808.09657,
  title  = {Updated evaluation of $\varepsilon_K$ in the Standard Model with lattice QCD inputs},
  author = {Jon A. Bailey and Sunkyu Lee and Weonjong Lee and Jaehoon Leem and Sungwoo Park},
  journal= {arXiv preprint arXiv:1808.09657},
  year   = {2018}
}

Comments

17 pages, 12 figures, references updated, title changed