Update on $varepsilon_K$ with lattice QCD inputs


Abstract in English

We report updated results for $varepsilon_K$, the indirect CP violation parameter in neutral kaons, which is evaluated directly from the standard model with lattice QCD inputs. We use lattice QCD inputs to fix $bar{B}_K$, $|V_{cb}|$, $xi_0$, $xi_2$, $|V_{us}|$, and $m_c(m_c)$. Since Lattice 2016, the UTfit group has updated the Wolfenstein parameters in the angle-only-fit method, and the HFLAV group has also updated $|V_{cb}|$. Our results show that the evaluation of $varepsilon_K$ with exclusive $|V_{cb}|$ (lattice QCD inputs) has $4.0sigma$ tension with the experimental value, while that with inclusive $|V_{cb}|$ (heavy quark expansion based on OPE and QCD sum rules) shows no tension.

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