Pion Distribution Amplitudes from Functional QCD

Abstract:

We present the first functional QCD calculation of the pion distribution amplitude (DA) using the large-momentum effective theory within the functional renormalisation group (fRG) approach. With only the strong coupling and current quark masses as inputs, we compute the quasi-DA from first-principles QCD correlation functions. By pushing the pion momentum up to Pz=4.5 GeV, the quasi-DA becomes fully saturated, rendering the extrapolation errors to the light-cone limit negligible. The resulting second-order moment ⟨ξ2⟩π=0.267 is significantly smaller than existing lattice-LaMET determinations and lies in a range consistent with other nonperturbative approaches.

L. Chang, W.-j. Fu, C. Huang, J. M. Pawlowski, Y.-y. Tan, „Pion Distribution Amplitudes from
Functional QCD“, 6. Juli 2026, arXiv:2607.04871 (2026).

https://arxiv.org/abs/2607.04871

Related to Project B03