Analysis of deep inelastic scattering with $z$-dependent scale

Abstract

Evolution of the parton densities at NLO in ${\alpha }_S$ using ${\tilde{W}}^2=Q^2(1-z)/z$ instead of the usual $Q^2$ for the scale of the running coupling ${\alpha }_S$ is investigated. While this renormalisation scale change was originally proposed as the relevant one for $x\to 1$, we explore the consequences for all $x$ with this choice. While it leads to no improvement to the description of DIS data, the nature of the gluon at low $x$, low $Q^2$ is different, avoiding the need for a `valence-like' gluon.

Comments: 13 pages including 5 figures