Gravitational Form Factors of Vector Mesons in an AdS/QCD Model
  We calculate gravitational form factors of vector mesons using a holographic model of QCD. These provide restrictions on the generalized parton distributions of vector mesons, via the sum rules connecting stress tensor form factors to GPDs. We concentrate on the traceless part of the stress tensor, which suffices to fix the momentum and angular momentum sum rules. The vector mesons appear noticeably more compact measured by the gravitational form factors than by the charge form factor. 
Zainul Abidin and Carl E. Carlson (William and Mary)