Scaling of the F_2 structure function in nuclei and quark distributions at x>1

TL;DR

This paper reports new electron scattering data from various nuclei at high momentum fractions, revealing a rapid falloff in cross sections for x>1, consistent with muon scattering but contrasting neutrino results, and highlighting differences among light and heavy nuclei.

Contribution

It provides new experimental data on nuclear structure functions at x>1, clarifying the behavior of high-momentum quarks and resolving discrepancies between different scattering experiments.

Findings

Rapid cross section falloff for x>1 in heavy nuclei

Agreement with muon scattering measurements

Contrast with neutrino scattering results

Abstract

We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for $x>1$, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.