Transverse Energy and Forward Jet Production in the Low $x$ Regime at HERA

TL;DR

This paper measures transverse energy and forward jet production at low x in deep inelastic scattering at HERA, comparing results to QCD models DGLAP and BFKL, and finds BFKL better explains the observed increase in transverse energy.

Contribution

It provides the first detailed comparison of transverse energy production with BFKL and DGLAP predictions at low x in deep inelastic scattering.

Findings

Transverse energy increases with decreasing x at fixed Q^2.

Data favors BFKL-based calculations over DGLAP in the low x regime.

Forward jet rates support BFKL dynamics as a signature.

Abstract

The production of transverse energy in deep inelastic scattering is measured as a function of the kinematic variables $x$ and $Q^2$ using the H1 detector at the ep collider HERA. The results are compared to the different predictions based upon two alternative QCD evolution equations, namely the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) and the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equations. In a pseudorapidity interval which is central in the hadronic centre of mass system between the current and the proton remnant fragmentation region the produced transverse energy increases with decreasing $x$ for constant $Q^2$. Such a behaviour can be explained with a QCD calculation based upon the BFKL ansatz. The rate of forward jets, proposed as a signature for BFKL dynamics, has been measured.