Origin of nucleon D-form-factor suppression

Determine whether the suppression of the nucleon gravitational D-form factor is uniquely associated with a nonzero chiral-invariant nucleon mass or can also arise from other mechanisms, including meson mixing and multiquark components.

Background

The paper reviews a previous parity doublet model analysis in which a nonzero chiral-invariant component of the nucleon mass suppresses the magnitude of the nucleon D-form factor and improves agreement with lattice-QCD data. The authors explicitly note that it is unresolved whether this suppression is a distinctive signature of the chiral-invariant mass or whether alternative mechanisms can produce a similar effect. They investigate meson mixing between two-quark and four-quark states in an extended linear sigma model as one such possible mechanism, finding quantitatively similar suppression. Consequently, the nucleon D-form factor alone may not distinguish the origin of the suppression, motivating complementary studies such as the pion D-form factor.