arXiv subjects

H. Jung

Publications and source records attributed to H. Jung.

135 records · Page 8Linked to original sources

arXiv1999

CCFM prediction on forward jets and $F_2$: parton level predictions and a new hadron level Monte Carlo generator CASCADE

A solution of the CCFM equation for a description of both the structure function $F_2$ and the cross section of forward jet production as measured by the HERA experiments is obtained on the basis of the parton level Monte Carlo program SMALLX. The treatment of the non - Sudakov form factor and the so - called "consistency constraint" are discussed. Following this a backward evolution scheme according to CCFM is developed which then is used to construct an efficient hadron level Monte Carlo program CASCADE. The results from the forward evolution and the backward evolution Monte Carlos are compared and found to be consistent.

hep-ph↗

arXiv1999

CCFM prediction for F_2 and forward jets at HERA

Predictions of the CCFM evolution equation for F_2 and forward jets at HERA energies are obtained from a modified version of the Monte Carlo program SMALLX. The treatment of the non-Sudakov form factor $Δ_{ns}$ is discussed as well as the effect of the so called "consistency constraint". For the first time a good description of F_2 and the forward jet data is obtained from the CCFM equation.

hep-ph↗

arXiv1999

The role of resolved virtual photons in the production of forward jets at HERA

The measurement of forward jet cross sections has been suggested as a promising probe of new small x parton dynamics and the question is whether the new HERA data provide an indication of this. In this paper the influence of resolved photon processes has been investigated and it has been studied to what extent the inclusion of such processes in addition to normal deep inelastic scattering leads to agreement with 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.

hep-ph↗

arXiv1999

Quark-Antiquark-Gluon Jets in DIS Diffractive Dissociation

We study the diffractive production of $q\bar{q}g$ jets with large transverse momenta in the region of large diffractive masses (small $β$). Cross sections for transverse and longitudinal photons are obtained in the leading log $1/x_{\fP}$ and log $1/β$ approximation, keeping all powers in log $k_t^2/Q^2$. We perform a numerical study and illustrate the angular distribution of the three jets. We also estimate the integrated diffractive three jet cross section and compare with the dijet cross section obtained before.

hep-ph↗

arXiv1998

Resolved virtual photons in the small $x$ domain

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 $α_s$ 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 $\xbj$ parton 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 $\xbj$ 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 the inclusion of such processes in addition to normal deep inelastic scattering leads to agreement with 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.

hep-ph↗

arXiv1998

Future Diffraction at HERA

Future prospects of hard diffraction at HERA a reviewed. A selection of processes which can be calculated in pQCD is given, with emphasis on the separation of soft and hard diffraction. The main focus will be put on the energy dependence of diffractive processes and signatures for the hard pQCD pomeron. Problems in the experimental detection of these processes and the expected significance of future measurements at HERA are discussed.

hep-ph↗

arXiv1998

Monte Carlo Implementations of Diffraction at HERA

The Monte Carlo implementation of different approaches for diffractive scattering in $e - p$ collisions (resolved $\PO$, pQCD, soft color interactions) is described, with emphasis on the construction of the hadronic final state. Simple models for proton dissociation and exclusive vector meson production are described. A comparison of the different approaches is given.

hep-ph↗

arXiv1998

Resolved photon processes in DIS and small x dynamics

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.

hep-ph↗

arXiv1997

Resolved Photons and BFKL-type Signatures in Deep Inelastic Scattering

The concept of resolved virtual photons in addition to direct deep inelastic $ep$ scattering is used to simulate the 2+1 jet - rate and the forward jet cross section, which cannot be described by direct LO/NLO processes. With standard DGLAP evolution of the parton densities of the virtual photon and the proton the HERA data can be described, provided a sufficiently large scale for the hard scattering matrix element is used.

hep-ph↗