Low Q^2 Structure Functions including the Longitudinal Structure Function
An NLO QCD analysis on the HERA combined cross sections obtained from the measurements using the data up to the year 2000 at both the H1 and ZEUS collaborations provides significantly improved parton distribution functions. In 2007, HERA successfully operated with reduced center-of-mass energies. Direct measurements of F_L were performed at x\sim10^{-3}, giving a good test of the perturbative QCD framework in describing proton structure.
hep-ex↗