QCD Physics Lessons of Z0 Decay

This talk contains a subjective selection of interesting results on Z$^0$ decays, presented by the LEP and SLC groups. The emphasis is on soft and semihard QCD physics. Results are put in a theoretical context, and the limits of our current understanding are stressed. Topics covered include event measures, prompt photons, coherence and string effects, data and theory for particle rates and spectra, particle correlations and Bose--Einstein effects.Comment: 9 pages, no figures, LaTeX2epsilon input, alternatively ready-made postscript file is available at http://thep.lu.se/tf2/staff/torbjorn/Welcome.htm

QED Interconnection Effects on W Momentum Distributions at LEP 2

The process \ee \to \W^+\W^- \to \f_1 \fbar_2 \, \f_3 \fbar_4 contains charges in the initial, intermediate and final stages. This gives a rich selection of possible QED interconnection effects. Coulomb interaction is the simplest of these, and can thus be used to explore consequences. We study a number of experimental observables, with emphasis on those related to the W momentum distribution. Second-order Coulomb effects are shown to be practically negligible. The limited LEP~2 statistics will not allow detailed tests, so any theory uncertainty will be reflected in the systematic error on the W mass. Currently the uncertainty from this source may be as high as 20~MeV.Comment: 1+27 pages, including 23 eps figures, use uudecode and gunzip to restore original file, run LaTeX2epsilon with epsfig package, figures are included in filecontents environments; alternatively ready-made postscript file is available at http://thep.lu.se/tf2/staff/torbjorn/Welcome.htm

PYTHIA 5.7 and JETSET 7.4 Physics and Manual

This is the latest edition of the physics description and manual of the PYTHIA and JETSET programs for event generation in High Energy Physics.Comment: 6+321 pages, use uudecode + gunzip + LaTeX2epsilon; alternatively ready-made postscript file is available at http://thep.lu.se/tf2/staff/torbjorn/Welcome.htm

Finite width effects in Higgs decays as a means of measuring massive particle widths

We calculate decays of a Standard Model Higgs boson to a virtual massive particle and discuss how this depends on the massive particle total width. If the partial width of Higgs to a virtual massive particle can be measured this gives a measurement of that massive particle's width. We discuss how one would go about measuring these partial widths of a Higgs experimentally, and how this could lead to a measurement of the $W$ boson and $t$ quark width. For the latter extreme dependence on the Higgs mass and the small $H\to tt^*$ branching ratios mean that little can be learnt about the $t$ quark width. For the former there is also large dependence on the Higgs mass; however this can be removed by taking the ratio of $H\to WW^*$ decays to $H\to ZZ^*$ decays. This ratio also has the advantage of being fairly insensitive to physics beyond the Standard Model. Unfortunately, for Higgs masses of interest the $H\to ZZ^*$ branching ratio is small enough that we require many 1000's of tagged Higgs decays before an accurate measurement of the $W$ width can be made. This is likely to be hard experimentally.Comment: 19 pages, TeX, 5 postscipt figures, uses epsf.tex available at http://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-861.ps.Z or ftp://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-861.ps.

γγ\gamma\gamma Event Generators

The report from the working group on '\gamma\gamma Event Generators' of the LEP 2 workshopComment: 42 pages, tared, gzipped, uuencoded. To be published in the proceedings of the LEP 2 Worksho

PYTHIA and HERWIG for linear collider physics

An overview is given of general-purpose event generators, especially PYTHIA and HERWIG. The current status is summarized, some recent physics improvements are described, and planned future projects are outlined.Comment: 1+4 pages, no figures, to appear in the Proceedings of the International Workshop on Linear Colliders, Sitges (Barcelona), Spain, April 28-May 5, 199