Axial couplings in heavy hadron chiral perturbation theory at the next-to-leading order

TL;DR

This paper calculates axial-current matrix elements in heavy hadron chiral perturbation theory at next-to-leading order, providing a framework to interpret lattice and experimental data for determining axial couplings.

Contribution

It extends heavy hadron chiral perturbation theory to next-to-leading order, including finite-size effects and partially-quenched scenarios, to aid lattice QCD data analysis.

Findings

Provides detailed formulas for axial-current matrix elements

Analyzes impact on lattice QCD results for SU(2) full QCD

Studies one-loop contributions to heavy hadron decay amplitudes

Abstract

We present calculations of axial-current matrix elements between various heavy-meson and heavy-baryon states to the next-to-leading order in heavy hadron chiral perturbation theory in the p-regime. When compared with data from lattice computations or experiments, these results can be used to determine the axial couplings in the chiral Lagrangian. Our calculation is performed in partially-quenched chiral perturbation theory for both SU(4|2) and SU(6|3). We incorporate finite-size effects arising from a single Goldstone meson wrapping around the spatial volume. Results for full QCD with two and three flavours can be obtained straightforwardly by taking the sea-quark masses to be equal to the valence-quark masses. To illustrate the impact of our chiral perturbation theory calculation on lattice computations, we analyse the SU(2) full QCD results in detail. We also study one-loop contributions relevant to the heavy hadron strong-decay amplitudes involving final-state Goldstone bosons, and demonstrate that the quark-mass dependence of these amplitudes can be significantly different from that of the axial current matrix elements containing only single hadron external states.