The Longitudinal Structure Function $F_L$ at small x

Abstract

We present a set of formulae to extract the longitudinal deep inelastic structure function $F_L$ from the transverse structure function $F_2$ and its derivative $d{F}_2/dln{Q}^2$ at small $x$. Using $F_2$ HERA data we obtain $F_L$ in the range $10^{-4}\le x\le 10^{-2}$ at $Q^2=20$ GeV${}^2$

Latex file (3 pages), 1 Postscript figures, uses procl.sty and psfig.tex. To appear in Proceedings of the Int. Workshop on DIS and Related Phenomena (Rome, April 1996)