Computation of the Heavy-Light Decay Constant using Non-relativistic Lattice QCD

TL;DR

This paper presents a lattice QCD calculation of the heavy-light meson decay constant using non-relativistic methods for heavy quarks, improving signal quality and providing results for B mesons and static limits.

Contribution

It introduces a non-relativistic lattice QCD approach for calculating heavy-light decay constants with enhanced signal extraction and compares results across different heavy quark masses.

Findings

Calculated f_B = 171±22^{+19}_{-45} MeV

Estimated deviation from heavy mass scaling law

Extrapolated static limit f_B^{static} = 297±36^{+15}_{-30} MeV

Abstract

We report results on a lattice calculation of the heavy-light meson decay constant employing the non-relativistic QCD approach for heavy quark and Wilson action for light quark. Simulations are carried out at $\beta=6.0$ on a $16^3\times 48$ lattice. Signal to noise ratio for the ground state is significantly improved compared to simulations in the static approximation, enabling us to extract the decay constant reliably. We compute the heavy-light decay constant for several values of heavy quark mass and estimate the magnitude of the deviation from the heavy mass scaling law $f_{P} \sqrt{m_{P}} = const$. For the $B$ meson we find $f_{B} = 171\pm 22^{+19}_{-45}$ MeV, while an extrapolation to the static limit yields $f_{B}^{static}$ = $297\pm 36^{+15}_{-30}$ MeV.