On the Rise of the Proton Structure Function F_2 Towards Low x

TL;DR

This paper measures how the proton structure function F_2 changes with x and Q^2 at very low x, revealing that its derivative depends linearly on ln(Q^2) and is independent of x in that range.

Contribution

It provides the first detailed measurement of the derivative of ln F_2 with respect to ln x at low x, showing its linear dependence on ln Q^2.

Findings

lambda(x,Q^2) is independent of x in the studied range

lambda(x,Q^2) increases linearly with ln(Q^2)

Results support models of proton structure at low x

Abstract

A measurement of the derivative (d ln F_2 / d lnx)_(Q^2)= -lambda(x,Q^2) of the proton structure function F_2 is presented in the low x domain of deeply inelastic positron-proton scattering. For 5*10^(-5)<=x<=0.01 and Q^2>=1.5 GeV^2, lambda(x,Q^2) is found to be independent of x and to increase linearly with ln(Q^2).