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K. Geiger

Publications and source records attributed to K. Geiger.

7 recordsLinked to original sources
arXiv1998

Bose-Einstein Correlations in a Space-Time Approach to e+ e- Annihilation into Hadrons

A new treatment of Bose-Einstein correlations is incorporated in a space-time parton-shower model for e+ e- annihilation into hadrons. Two alternative afterburners are discussed, and we use a simple calculable model to demonstrate that they reproduce successfully the size of the hadron emission region. One of the afterburners is used to calculate two-pion correlations in e+ e- -> Z^0 -> hadrons and e+ e- -> W+ W- -> hadrons. Results are shown with and without resonance decays, for correlations along and transverse to the thrust jet axis in these two classes of events.

hep-ph↗
arXiv1994

Effective Field Theory Approach to Parton-Hadron Conversion in High Energy QCD Processes

A QCD based effective action is constructed to describe the dynamics of confinement and symmetry breaking in the process of parton-hadron conversion. The deconfined quark and gluon degrees of freedom of the perturbative QCD vacuum are coupled to color singlet collective fields representing the non-perturbative vacuum with broken scale and chiral symmetry. The effective action recovers QCD with its scale and chiral symmetry properties at short space-time distances, but yields at large distances (r > 1 fm) to the formation of symmetry breaking gluon and quark condensates. The approach is applied to the evolution of a fragmenting $q\bar q$ pair with its generated gluon distribution, starting from a large hard scale $Q^2$. The modification of the gluon distribution arising from the coupling to the non-perturbative collective field results eventually in a complete condensation of gluons. Color flux tube configurations of the gluons in between the $q\bar q$ pair are obtained as solutions of the equations of motion. With reasonable parameter choice, the associated energy per unit length (string tension) comes out $\simeq 1$ GeV/fm, consistent with common estimates.

hep-ph↗
arXiv1994

Dynamic Gluon Confinement in High Energy Processes within Effective QCD Field Theory

An effective Lagrangian approach to describe the dynamics of confinement and symmetry breaking in the process of quark-gluon to hadron conversion is proposed. The deconfined quark and gluon degrees of freedom of the perturbative QCD vacuum are coupled to color neutral condensate fields representing the non-perturbative vacuum with broken scale and chiral symmetry. As a first application the evolution of gluons emitted by a fragmenting high energy $q\bar q$ pair from the perturbative to the non-perturbative regime with confinement is studied. For reasonable parameter choice the solution of the equations of motion leads to flux tube configurations with a string tension $t \simeq 1$ GeV/fm.

hep-ph↗
arXiv1994

Chemical Equilibration in the Parton Cascade Model

This comment is hereby withdrawn, because the paper by D. Seibert, KSUCNR-005-94 and nucl-th/9403005 was withdrawn and it was acknowleged that the parton cascade model does approach chemical equilibrium correctly. Therefore our reply to Seibert's paper is now obsolete.

hep-ph↗
arXiv1994

Analytic Solutions of QCD Evolution Equations for Parton Cascades Inside Nuclear Matter at Small X

An analytical method is presented to solve generalized QCD evolution equations for the time development of parton cascades in a nuclear environment. Closed solutions for the spectra of produced partons with respect to the variables time, longitudinal momentum and virtuality are obtained under some idealizing assumptions about the composition of the nuclear medium. Several characteristic features of the resulting parton distributions are discussed. One of the main conclusions is that the evolution of a parton shower in medium is dilated as compared to free space and is accompanied by an enhancement of particle production. These effects become stronger with increasing nuclear density.

hep-ph↗