J. Kripfganz

Statistical bootstrap of fireball decay spectra

Quantum number conservation is considered within the stastistical bootstrap model by generalizing the bootstrap equation for the generating functional of fireball decay spectra. Explicit solutions are given for the level density and the generating functional in the case of additive quantum nunnbers as well as isospin conservation. Asymptotic expressions for the level density, the inclusive single and two-particle distributions and the generating function of the multiplicity distribution are derived in the case of charge conservation. Multiplicity moments from proton-- antiproton annihilation into pions are compared with the model. (auth)

Quantum number conservation in the statistical bootstrap of fireball decay spectra

Abstract Quantum number conservation is considered within the statistical bootstrap model by generalizing the bootstrap equation for the generating function of fireball decay spectra. Explicit solutions are given for the level density and the generating functional in the case of additive quantum numbers as well as isospin conservation. Asymptotic expressions for the level density, the inclusive single and two-particle distributions and the generating fuhnction of the multiplicity distribution are derived in the case of charge conservation. Multiplicity moments from proton-antiproton annihilation into pions are compared with the model.

Dynamical fermions at non-Zero chemical potential and temperature: Mean field approach

We derive a strong coupling effective Lagrangian describing Wilson lines coupled to quark bilinears. Wilson line and dynamical quark mass are studied in mean field approximation. A second-order finite-temperature chiral phase transition is found at zero chemical potential μ. For μ≠0 this transition becomes a first-order one.

Short-distance expansion of Wilson loops, gluon condensation and Monte Carlo lattice results

Abstract The short-distance expansion of Wilson loops in terms of composite gluon operators (gluon condensate) is studied. The 2-loop perturbative contribution to Wilson loop rations is evaluated. Monte Carlo lattice results for SU(2) gluodynamics are analyzed in terms of this expansion. Consistent results for the gluon condensate are found.

Multihadron production in nucleon--antinucleon annihilation at rest in the statistical bootstrap model. I. Multiplicity distributions according to different bootstrap versions

Abstract Multihadron production in nucleon-antinucleon annihilation at rest is studied using the statistical bootstrap model. Different versions of the statistical bootstrap model are compared at non-asymptotic and asymptotic energies. The parameter of the model is determined from nucleon-antinucleon annihilation at rest. Data for p p and p n annihilation agree rather well with the model except for certain difficulties with neutral pions. Furthermore we discuss the fireball mass dependence of the bootstrap predictions and in this context the application of the statistical bootstrap model to e − e + → hadrons.

Electroweak radiative corrections and quark mass singularities

A consistent method to remove quark mass singularities from physical cross sections is demonstrated. They are factorised into quark and gluon distribution functions. This implies electromagnetic correction terms to theQ2 dependent structure functions. They are calculated in leading order in the fine structure constant α and found to be flat and small overx.

QCD three-jet production in large-p⊥ processes

Abstract The contribution of the hard scattering subprocess quark + quark → quark + quark + gluon to two-particle inclusive distributions at large p ⊥ is studied. It is shown to be accessible experimentally, and agrees with recent data on azimuthal distributions in the adequate kinematical region.

The decay of the sphaleron

Abstract Baryon number violation in the electroweak standard model is expected to proceed through classical transitions over the sphaleron barrier connecting vacua of different Chern-Simons number. The required energy is the order of 10 TeV. The event structure is studied in this paper by following the real-time evolution of the sphaleron field configuration. On average, the sphaleron is found to decay into 42 W-bosons and 8 Higgs particles, if the Higgs mass is close to the W-boson mass.

Multiplicity distributions in a multiperipheral fireball model

Abstract Multiplicity distributions are studied in the thermodynamic model. The approximate Koba, Nielsen, Olesen scaling behaviour of the data and Wroblewskis linear law can be understood in the thermodynamic model with multiperipheral production of fireballs. This production mechanism is also essential to understand two-particle rapidity correlations especially in the ISR energy range. There are contributions from diffractive and non-diffractive production of fireballs in the model, which agrees in this sense with the two-component models used recently to discuss multiplicity distributions. In contrast to other models, however, the non-diffractive component taken separately exhibits approximate KNO-scaling and accounts rather well for the behaviour of the data up to 300 GeV. For the fireball production mechanism choosen the cross section of the diffractive component is expected to be smaller than in other models and can lead to a two-maxima multiplicity distribution only at energies higher than predicted in other models.

Statistical bootstrap without exotic states

Abstract Fireball decay is studied in the framework of a linear statistical bootstrap model with full isospin conservation. The fireball isospin is restricted to the values 0 and 1. This restriction causes a modification of the temperature relation compared with the unrestricted case. The first few inclusive decay distributions, however, remain nearly unaltered. The asymptotic average multiplicities of π + , π o , π − are found to be equal.