Proton gravitational form factors in a light-front quark-diquark model

Abstract

We present a recent calculation of the gravitational form factors (GFFs) of proton using the light-front quark-diquark model constructed by the soft-wall AdS/QCD[1]. The four GFFs ~A(Q^2)A(Q2) , B(Q^2)B(Q2) , C(Q^2)C(Q2) and \bar{C}(Q^2)C‾(Q2) are calculated in this model. We also show the pressure and shear distributions of quarks inside the proton. The GFFs, A(Q^2)A(Q2) and B(Q^2)B(Q2) are found to be consistent with the lattice QCD, while the qualitative behavior of the DD-term form factor is in agreement with the extracted data from the deeply virtual Compton scattering (DVCS) experiments at JLab, the lattice QCD, and the predictions of different phenomenological models.

Gravitational Form Factors and Mechanical Properties of the Proton : Connection Between Distributions in 2D and 3D

“…We have used the higher-order perturbative parton evolution toolkit (HOPPET) [44] to perform the scale evolution numerically. We find that the QCD evolution of the GFFs A u+d (Q 2 ), B u+d (Q 2 ) are consistent with the lattice QCD results [28,40]. Also the qualitative behavior of our D-term is comparable with the lattice QCD [45] and the experimental data from JLab [13] as well as other theoretical predictions from the KM15 global fit [46], dispersion relation [47], χQSM [22], Skyrme model [24], and bag model [48].…”

“…(( 24), ( 25) and ( 26)) is found to be very lengthy and not so intuitive. It turns out that the form factor D(Q 2 ) ≡ D u+d (Q 2 ) can be described by the multipole function as [40], GFFs are discussed in the reference [28]. In Table I fitted model parameters in the first row are extracted at the initial scale µ 2 0 = 0.32 GeV 2 , whereas the fitted parameters in the second row correspond to the scale evolution from initial scale µ 2 = 0.32 GeV 2 to the final scale µ 2 = 4 GeV 2 .…”