B meson B-parameters and the decay constant in two-flavor dynamical QCD

TL;DR

This study calculates B meson B-parameters and decay constant in two-flavor dynamical QCD, revealing sea quark effects on decay constants but not on B parameters, using lattice QCD techniques.

Contribution

It provides the first dynamical QCD calculation of B meson parameters with nonperturbative O(a) improvement and compares chiral extrapolation methods with ChPT predictions.

Findings

Sea quark effects increase the decay constant.

No significant sea quark effect on B parameters.

Chiral extrapolation with logarithmic terms aligns with ChPT.

Abstract

We present a two-flavor dynamical QCD calculation of the B meson B parameters and decay constant. We use NRQCD for heavy quark and the nonperturbatively O(a)-improved Wilson action for light quark at $\beta$=5.2 on a $20^3\times 48$ lattice. We confirm that the sea quark effect increases the heavy-light decay constant, while estimate of its magnitude depends significantly on the fitting form in the chiral extrapolation. For the B parameters, on the other hand, we do not find a significant sea quark effect. The chiral extrapolation with logarithmic term is examined for both quantities and compared with the prediction of ChPT.