Measurement of the proton structure function F L (x, Q 2) at low x


Aaron F., Alexa C., Andreev V., Antunovic B., Aplin S., Asmone A., ...More

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol.665, no.4, pp.139-146, 2008 (SCI-Expanded) identifier identifier

Abstract

A first measurement is reported of the longitudinal proton structure function F L (x, Q 2) at the ep collider HERA. It 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. Employing the energy dependence of the cross section, F L is measured in a range of squared four-momentum transfers 12 ≤ Q 2 ≤ 90 GeV 2 and low Bjorken x 0.00024 ≤ x ≤ 0.0036. The F L values agree with higher order QCD calculations based on parton densities obtained using cross section data previously measured at HERA. © 2008 Elsevier B.V. All rights reserved.