Generalized parton distributions and transverse densities in a light-front quark–diquark model for the nucleons

Abstract

We present a study of the generalized parton distributions (GPDs) for the quarks in a proton in both momentum and position spaces using the light-front wave functions (LFWFs) of a quark-diquark model for the nucleon predicted by the soft-wall model of AdS/QCD. The results are compared with the soft-wall AdS/QCD model of proton GPDs for zero skewness. We also calculate the GPDs for nonzero skewness. We observe that the GPDs have a diffraction pattern in longitudinal position space, as seen before in other models. Then we present a comparative study of the nucleon charge and anomalous magnetization densities in the transverse plane. Flavor decompositions of the form factors and transverse densities are also discussed.

Deuteron transverse densities in holographic QCD

“…However, the transverse densities defined at fixed light-front time have a proper density interpretation [99,100,101]. The charge densities in the transverse impact parameter plane for the nucleon have been discussed extensively in various phenomenological models [63,64,74,102,103,104,105,106,107,108,109], whereas the densities in the transverse coordinate plane have been studied in [110,111,112]. In [113], the deuteron transverse charge density has been evaluated using different parameterizations of the charge form factor and it has been shown that the different parameterizations provide different densities in particular at the center of the impact parameter (b = 0).…”

Longitudinal momentum densities in transverse plane for nucleons

“…According to the standard interpretation [33,52,[65][66][67][68], in the light-cone frame with q + = q 1 + q 3 = 0, the charge and anomalous magnetization densities in the transverse plane can be interpreted with the two-dimensional Fourier transform (FT) of the Dirac and Pauli form factors. Similar to the electromagnetic densities, one can identify the gravitomagnetic density in the transverse plane by taking the FT of the gravitational form factor [41,52].…”

The renormalization scale problem and novel perspectives for QCD

“…The moments of the structure function and other distributions can then be evaluated as overlaps of the target hadron's light-front wavefunction (LFWF), the hadronic eigensolution of the LF Hamiltonian, as in the Drell-Yan-West formulae for hadronic form factors. [80][81][82][83] The phases of the resulting DIS amplitude and OPE matrix elements reflect the real phase of the stable target hadron's wavefunction. This approximation defines the "static" contribution 54,84 to the measured parton distribution functions (PDF), transverse momentum distributions, etc.…”