A model for the longitudinal structure function FL at low x and low Q2 is presented, which includes the kinematical constraint FL∼Q4 as Q2 → 0. It is based on the photon-gluon fusion mechanism suitably extrapolated to the region of low Q2. The contribution of quarks having limited transverse momentum is treated phenomenologically assuming that it is described by the soft pomeron exchange mechanism. The ratio R = FL/(F2 - FL), with the F2 appropriately extrapolated to the region of low Q2, is also discussed.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)