2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/172095The first measurements of the longitudinal proton structure function FL in deep inelastic positron-proton scattering at low Bjorken x are described. Theoretical predictions in higher order QCD and using dipol model calculations are consistent with the measurements. The data were taken by the HERA experiments H1 and ZEUS in a series of runs with different proton beam energies in 2007.Parallel talk at ICHEP08, Philadelphia, USA, July 2008. 4 pages, LaTeX, 2 eps figuresHigh Energy Physics - Experimenttext