Measurement of R = sigma_L / sigma_T and the Separated Longitudinal and Transverse Structure Functions in the Nucleon Resonance Region

TL;DR

This study provides detailed measurements of the ratio of longitudinal to transverse cross sections and separated structure functions in the nucleon resonance region, revealing significant resonance contributions and observing quark-hadron duality at higher Q^2.

Contribution

First precise separation of F_1 and F_L structure functions in the nucleon resonance region using Rosenbluth technique at Jefferson Lab.

Findings

Resonance longitudinal component is significant and shows distinct mass peaks.

Observation of quark-hadron duality above Q^2 = 1 GeV^2.

Accurate R = sigma_L / sigma_T data across a wide Q^2 range.

Abstract

We report on a detailed study of longitudinal strength in the nucleon resonance region, presenting new results from inclusive electron-proton cross sections measured at Jefferson Lab Hall C in the four-momentum transfer range 0.2 < Q^2 < 5.5 GeV^2. The data have been used to accurately perform 167 Rosenbluth-type longitudinal / transverse separations. The precision R = sigma_L / sigma_T data are presented here, along with the first separate values of the inelastic structure functions F_1 and F_L in this regime. The resonance longitudinal component is found to be significant, both in magnitude and in the existence of defined mass peaks. Additionally, quark-hadron duality is here observed above Q^2 = 1 GeV^2 in the separated structure functions independently.