Lattice QCD calculation of the pion distribution amplitude with domain wall fermions at physical pion mass
Ethan Baker, Dennis Bollweg, Peter Boyle, Ian C. Cloët, Xiang Gao, Swagato Mukherjee, Péter Petreczky, Rui Zhang, Yong Zhao
Abstract
A bstract We present a direct lattice QCD calculation of the x -dependence of the pion distribution amplitude (DA), which is performed using the quasi-DA in large momentum effective theory on a domain-wall fermion ensemble at physical quark masses and spacing a ≈ 0.084 fm. The bare quais-DA matrix elements are renormalized in the hybrid scheme and matched to $$ \overline{\textrm{MS}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>MS</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> with a subtraction of the leading renormalon in the Wilson-line mass. For the first time, we include threshold resummation in the perturbative matching onto the light-cone DA, which resums the large logarithms in the soft gluon limit at next-to-next-to-leading log. The resummed results show controlled scale-variation uncertainty within the range of momentum fraction x ∈ [0.25, 0.75] at the largest pion momentum P z ≈ 1 . 85 GeV. In addition, we apply the same analysis to quasi-DAs from a highly-improved-staggered-quark ensemble at physical pion mass and a = 0 . 076 fm. By comparison we find with 2 σ confidence level that the DA obtained from chiral fermions is flatter and lower near x = 0 . 5.