Photon Leading Twist Transverse Momentum Dependent Parton Distributions

TL;DR

This paper calculates the leading-twist transverse momentum dependent parton distribution functions (TMDs) for photons, considering both real and virtual cases, and compares results with existing models to understand photon structure.

Contribution

It provides explicit calculations of photon TMDs as helicity amplitudes, including mass effects, and compares polarized TMDs for different photon masses, advancing photon structure knowledge.

Findings

Unpolarized photon PDFs agree with existing models.

Presented explicit helicity amplitude forms of photon TMDs.

Analyzed spin-spin correlations between quarks and photons.

Abstract

In this work, we have calculated the photon leading-twist T-even transverse momentum dependent parton distribution functions (TMDs). For these calculations, we have treated photon as a state of quark anti-quark pair and represent the TMDs in explicit form of helicity amplitudes. We have presented all the T-even TMDs for the photon being massless (real) and massive (virtual). We have also compared our longitudinally and transversely polarized TMDs results for different photon masses. The collinear parton distribution functions (PDFs) have been predicted for both the real and virtual photon cases. The results for the unpolarized PDF of our calculations are in good agreement with other model predictions. In addition to this, we have also discussed the spin-spin correlations between the quark and photon.