Pion gravitational form factors in the QCD instanton vacuum. II
Wei-Yang Liu, Edward Shuryak, Ismaïl Zahed
Abstract
We revisit the hard QCD contributions to the pion gravitational form factors, in terms of the twist-2,3 pion distribution amplitudes (DAs), including novel semihard contributions from the instantons. The pion DAs are evaluated in the QCD instanton vacuum and then properly evolved to higher resolution. The results are compared to our recent results from the QCD instanton vacuum, as well as Bethe-Salpeter calculations and recent lattice data. The interpolated hard and soft contributions to the pion <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>D</a:mi> </a:math> form factor are used to derive the (gravitational) pressure and shear within the pion, with a clear delineation of their range. Published by the American Physical Society 2024