Measurement of the Proton Structure Function FL (x, Q~2) with the H1 Experiment

摘要

A preliminary measurement is reported of the longitudinal proton structure function F_L(x, Q~2) obtained from the H1 experiment at the ep collider HERA. This is the first measurement of the longitudinal structure function in a range of squared four-momentum transfer 2.5 ≤ Q~2 ≤ 800 GeV~2. Employing the energy dependence of the cross section, the measurement is based on inclusive deep inelastic e~+ p scattering cross section measurements with a positron beam energy of 27.5 GeV and proton beam energies of 920, 575 and 460 GeV. The measure F_L values are compared with higher order QCD calculations based on parton densities obtained using cross section data previously measured at HERA.