Sign of the nucleon gravitational D-term form factor at zero momentum transfer

Determine whether the total QCD energy–momentum-tensor gravitational form factor satisfies $D(0)<0$, thereby establishing the conjectured negative sign motivated by stability arguments.

Background

The paper discusses the gravitational form factor $D(t)$ appearing in the parametrization of the nucleon energy–momentum tensor. Unlike the normalization constraints on $A(0)$ and $J(0)$, Poincaré symmetry does not constrain the value of $D(0)$.

A negative value has been conjectured on the basis of stability arguments, but the sentence does not present a proof or derivation of this sign within QCD. Establishing whether $D(0)$ is indeed negative is therefore an explicitly identified unresolved conjecture relevant to the mechanical stability of hadrons.