Pinning down the Glue in the Proton

Abstract

The latest measurements of $F_2$ at HERA allow for a {\it combination} of gluon and sea quark distributions at small $x$ that is significantly different from those of existing parton sets. We perform a new global fit to deep-inelastic and related data. We find a gluon distribution which is larger for $x\text{lapproxeq}0.01$, and smaller for $x\sim 0.1$, and a flatter input sea quark distribution than those obtained in our most recent global analysis. The new fit also gives ${\alpha }_s(M_Z^2)=0.114$. We study other experimental information available for the gluon including, in particular, the constraints coming from fixed-target and collider prompt $\gamma$ production data.

Comments: 8 pages, LATEX, 6 figs available as .uu file