Heavy-quark contributions to the ratio F_L/F_2 at low x

TL;DR

This paper analyzes the heavy-quark contributions to proton structure functions at low x, providing formulas for their ratios that aid in experimental data interpretation and explaining their x-independence.

Contribution

It introduces compact formulas for the ratios of heavy-quark structure functions, enhancing the extraction of F_2^i from deep-inelastic scattering data at small x.

Findings

R_i is approximately independent of x

Formulas simplify the extraction of F_2^i from data

The approach explains the x-independence of R_i in the small-x regime

Abstract

We study the heavy-quark contribution to the proton structure functions F_2^i(x,Q^2) and F_L^i(x,Q^2), with i=c,b, for small values of Bjorken's x variable at next-to-lading order and provide compact formulas for their ratios R_i=F_L^i/F_2^i that are useful to extract F_2^i(x,Q^2) from measurements of the doubly differential cross section of inclusive deep-inelastic scattering at DESY HERA. Our approach naturally explains why R_i is approximately independent of x and the details of the parton distributions in the small-x regime.