Measurement of the proton and deuteron structure functions, F2 and F2, and of the ratio

TLDR

The New Muon Collaboration measured muon–proton and muon–deuteron inclusive deep‑inelastic scattering cross sections over 0.002 < x < 0.60 and 0.5 < Q² < 75 GeV² using 90–280 GeV muon beams, including small‑angle trigger data, enabling extraction of F₂ and the longitudinal‑to‑transverse cross‑section ratio R. The extracted F₂^p and F₂^d values agree with previous experiments, and the measured R ratio is consistent with perturbative QCD predictions, matching earlier data and extending to lower x.

Abstract

The muon-proton and muon-deuteron inclusive deep inelastic scattering cross sections were measured in the kinematic range 0.002 < × < 0.60 and 0.5 < Q2 < 75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results are based on the full data set collected by the New Muon Collaboration, including the data taken with a small angle trigger. The extracted values of the structure functions F2p and F2d are in good agreement with those from other experiments. The data cover a sufficient range of y to allow the determination of the ratio of the longitudinally to transversely polarised virtual photon absorption cross sections, R = σLσT, for 0.002 < × < 0.12. The values of R are compatible with a perturbative QCD prediction; they agree with earlier measurements and extend to smaller x.