A realistic method to access heavy meson light-cone distribution amplitudes from first-principle

Abstract

Lightcone distribution amplitudes (LCDAs) of heavy meson within heavy quark effective theory (HQET) are crucial for predicting physical observables in $B$ decays, but unfortunately there is no first-principle result due to severe challenges. After analyzing these challenges, we propose a realistic method to determine heavy meson LCDA. We utilize equal-time correlations and incorporate a dynamic quark field for a fast moving heavy quark. To verify this method, we make use of lattice QCD simulation on a lattice ensemble with spacing $a = 0.05187$\,fm. The preliminary findings for HQET LCDAs qualitatively align with phenomenological models, and the fitted result for the first inverse moment $\lambda_B^{-1}$ is consistent with the experimentally constrain from $B \to \gamma \ell\nu_\ell$. We explore how our findings can reduce model uncertainties in predictions of heavy-to-light form factors at large recoil. These results demonstrate the promise of our method in providing first-principle predictions for heavy meson LCDAs.