Update on ɛ_K with lattice QCD inputs

¹ Lattice Gauge Theory Research Center, CTP, Department of Physics and Astronomy, Seoul National University, Seoul 08826, South Korea
² Los Alamos National Laboratory, Theoretical Division T-2, Los Alamos, New Mexico 87545, USA
³ Brookhaven National Laboratory, Department of Physics, Upton, New York 11973, USA

^* Speaker, e-mail: wlee@snu.ac.kr

Published online: 26 March 2018

Abstract

We report updated results for ɛ_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 ${\stackrel{⌢}{B}}_K,\left|V_{cb}\right|,{\xi }_0,{\xi }_2,\left|V_{us}\right|$, 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 ɛ_K with exclusive |V_cb| (lattice QCD inputs) has 4.0σ tension with the experimental value, while that with inclusive |V_cb| (heavy quark expansion based on OPE and QCD sum rules) shows no tension.