  In the standard model (SM), the CP violation is introduced through a single
phase in the CKM matrix. The neutral kaon system is one of the most precise
channels to test how the SM theory describes the experiment data such as
$\epsilon_K$ accurately. The indirect CP violation is parametrized into
$\epsilon_{K}$, which can be calculated directly using lattice QCD. In this
calculation, the largest uncertainty comes from two sources: one is $\hat{B}_K$
and the other is $V_{cb}$. We use the lattice results of $\hat{B}_K$ and
exclusive $V_{cb}$ to calculate the theoretical estimate of $\epsilon_K$, which
turns out to be $3.1\sigma$ away from its experimental value. Here, the error
is evaluated using the standard error propagation method.
