A model for $F_L$ structure function at low values of $Q^2$ and $x$ - revisited

Abstract

A reanalysis of the model for the longitudinal structure function F_L (x,Q^2)FL(x,Q2) at low xx and low Q^2Q2 was undertaken, in view of the advent of the EIC. The model includes the kinematic constraint F_L\sim Q^4FL∼Q4 as Q^2\rightarrowQ2→ 0. It is based on the photon-gluon fusion mechanism suitably extrapolated to the region of low Q^2Q2. Revised model was critically updated, extended to the EIC kinematic region, and e.g. contains new parameterisations of the parton distribution functions.