Resolved photon processes in DIS and small x dynamics

TL;DR

This paper investigates the role of resolved photon processes in deep inelastic scattering at small x, showing that standard DGLAP evolution can explain certain HERA data previously attributed to BFKL dynamics.

Contribution

It demonstrates that resolved photon processes with two DGLAP chains can account for small x effects in DIS data, challenging the necessity of BFKL-based explanations.

Findings

Resolved photon processes can reproduce forward jet data.

Two DGLAP chains suffice to explain small x effects.

Conventional models can describe phenomena previously attributed to BFKL.

Abstract

It has been found that recent results on forward jet production from deep inelastic scattering can neither be reproduced by models which are based on leading order alpha_s QCD matrix elements and parton showers nor by next-to-leading order calculations. The measurement of forward jet cross sections has been suggested as a promising probe of new small x dynamics and the question is whether these data provide an indication of this. The same question arises for other experimental data in deep inelastic scattering at small x which can not be described by conventional models for deep inelastic scattering. In this paper the influence of resolved photon processes has been investigated and it has been studied to what extent such processes are able to reproduce the data. It is shown that two DGLAP evolution chains from the hard scattering process towards the proton and the photon, respectively, are sufficient to describe effects, observed in the HERA data, which have been attributed to BFKL dynamics.