Quark and gluon GPDs at finite skewness from strings in holographic QCD: evolved and compared to experiment

Abstract

We present a framework for constructing Generalized Parton Distributions (GPDs) using holographic QCD in the large $N_c$ limit, with a focus on low-x and finite skewness. Our approach utilizes holographic amplitudes for exclusive electroproduction processes to extract the spin-j conformal (Gegenbauer) moments of GPDs, which are then evolved to higher resolution scales using QCD evolution equations. Our evolved GPDs (reconstructed from their evolved conformal moments) are applied to analyze the electroproduction of ${\rho }^{0,+}$ and $\varphi$ mesons, and we account for non-perturbative contributions in the $s+u$ - channel using holographic QCD. The results compare well with the existing experimental data. Our GPDs provide detailed information about partonic distributions and are useful for future experimental studies and global data analyses.

Comments: v3: 79 pages (including 43 pages of appendix), reorganized for clarity, updated 1 table, updated 15 figures