Inclusive Electron Scattering in the Resonance Region off a Hydrogen Target with CLAS12

TL;DR

This paper reports the first absolute inclusive electron scattering cross sections off hydrogen at high energies using CLAS12, covering a wide kinematic range to study nucleon resonance structures and parton distributions.

Contribution

It provides new high-precision measurements of electron scattering cross sections in the resonance region with CLAS12, extending the understanding of nucleon resonance Q^2 evolution up to 10 GeV^2.

Findings

Cross sections cover W from pion threshold to 2.5 GeV across Q^2 from 2.55 to 10.4 GeV^2.

Comparison with resonance electroexcitation amplitudes shows promising insights into Q^2 evolution.

Results enable probing nucleon parton distributions at large x in the resonance region.

Abstract

Inclusive electron scattering cross sections off a hydrogen target at a beam energy of 10.6 GeV have been measured with data collected from the CLAS12 spectrometer at Jefferson Laboratory. These first absolute cross sections from CLAS12 cover a wide kinematic area in invariant mass W of the final state hadrons from the pion threshold up to 2.5 GeV for each bin in virtual photon four-momentum transfer squared $Q^2$ from 2.55 to 10.4~GeV$^2$ owing to the large scattering angle acceptance of the CLAS12 detector. Comparison of the cross sections with the resonant contributions computed from the CLAS results on the nucleon resonance electroexcitation amplitudes has demonstrated a promising opportunity to extend the information on their $Q^2$ evolution up to 10 GeV$^2$. Together these results from CLAS and CLAS12 offer good prospects for probing the nucleon parton distributions at large fractional parton momenta $x$ for $W$ < 2.5 GeV, while covering the range of distances where the transition from the strongly coupled to the perturbative regimes is expected.