Global QCD fit fromQ2=0toQ2=30 000 GeV2with Regge-compatible initial condition

Abstract

In this paper I show that it is possible to use Regge theory to constrain the initial parton distribution functions of a global Dokshitzer, Gribov, Lipatov, Altarelli, and Parisi (DGLAP) fit. In this approach, both quarks and gluons have the same high-energy behavior which may also be used to describe soft interactions. More precisely, I show that, if we parametrize the parton distributions with a triple-pole pomeron, i.e. like ${log}^{2}(1/x)$ at small $x$, at ${Q}^{2}={Q}_{0}^{2}$ and evolve these distributions with the DGLAP equation, we can reproduce ${F}_{2}^{p}$, ${F}_{2}^{d}$, ${F}_{2}^{n}/{F}_{2}^{p}$, ${F}_{2}^{\ensuremath{\nu}N}$, and $x{F}_{3}^{\ensuremath{\nu}N}$ for ${W}^{2}\ensuremath{\ge}12.5\text{ }\text{ }{\mathrm{GeV}}^{2}$. In this case, we obtain a new leading-order global QCD fit with a Regge-compatible initial condition. I shall also show that it is possible to use Regge theory to extend the parton distribution functions to small ${Q}^{2}$. This leads to a description of the structure functions over the whole ${Q}^{2}$ range based on Regge theory at low ${Q}^{2}$ and on QCD at large ${Q}^{2}$. Finally, I shall argue that, at large ${Q}^{2}$, the parton distribution functions obtained from DGLAP evolution and containing an essential singularity at $j=1$ can be approximated by a triple-pole pomeron behavior.