A Measurement and QCD Analysis of the Proton Structure Function $F_2(x,Q^2)$ at HERA

TL;DR

This paper presents a comprehensive measurement of the proton structure function $F_2(x,Q^2)$ across a wide kinematic range, revealing its increase at low $x$ and providing a QCD-based gluon density extraction, using enhanced data from HERA.

Contribution

It provides the first detailed measurement of $F_2$ at very low $Q^2$ and $x$ with significantly increased statistics and extends the kinematic coverage using innovative analysis techniques.

Findings

$F_2$ increases significantly at low $x$

Data are well described by NLO QCD fits

Gluon density is extracted from the data

Abstract

A new measurement of the proton structure function $F_2(x,Q^2)$ is reported for momentum transfers squared $Q^2$ between 1.5 GeV$^2$ and 5000 GeV$^2$ and for Bjorken $x$ between $3\cdot 10^{-5}$ and 0.32 using data collected by the HERA experiment H1 in 1994. The data represent an increase in statistics by a factor of ten with respect to the analysis of the 1993 data. Substantial extension of the kinematic range towards low $Q^2$ and $x$ has been achieved using dedicated data samples and events with initial state photon radiation. The structure function is found to increase significantly with decreasing $x$, even in the lowest accessible $Q^2$ region. The data are well described by a Next to Leading Order QCD fit and the gluon density is extracted.