We study the kaon quasi-distribution amplitude (quasi-DA) and distribution amplitude (DA) within the large-momentum effective theory (LaMET) combined with the first-principles functional QCD. Using quark correlation functions and the kaon Bethe-Salpeter amplitude in the Euclidean space from the 2+1 flavour functional QCD [1] as inputs, we obtain the kaon quasi DA in the large longitudinal momentum region with the contour deformation method [2] in the complex plane of momentum. By performing 1/Pz2 and 1/Pz4 order extrapolations of the kaon quasi-DA for the choices of the maximal longitudinal momentum Pzmax∈[2,2.5] GeV, we obtain a single-peaked and asymmetric kaon DA with the uncertainties arising from the extrapolation interval and ansatz. We find the first and second order moments of the kaon DA, ⟨ξ⟩K=0.020(3) and ⟨ξ2⟩K=0.253(12), respectively.
@article{arxiv.2604.23739,
title = {Kaon Distribution Amplitudes from Euclidean Functional QCD},
author = {Wen Cui and Dao-yu Zhang and Chuang Huang and Wei-jie Fu},
journal= {arXiv preprint arXiv:2604.23739},
year = {2026}
}