The polarized photon distribution function

Abstract: We employ the LuxQED approach to compute the polarized photon PDF (photon pPDF). This approach expresses the pPDF in terms of the structure functions $g_1$ and $g_2$. Different models for the structure functions are employed according to the parameter space region. The resulting pPDF is approximately of the order of $x$ times the unpolarized PDF. The relative uncertainty in the photon pPDF reaches up to $50\%$ for $x \sim 10^{-3}$, decreasing to approximately $10\%$ for higher values of $x$. The computation of the photon pPDF will be essential for improving the precision of polarized calculations and will have fundamental implications for studies at the future Electron-Ion Collider (EIC).