The Pythia program can be used to generate high-energy-physics ''events'', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.

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PYTHIA 6.4 Physics and Manual

HERWIG is a general-purpose Monte Carlo event generator, which includes the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron scattering and soft hadron-hadron collisions in one package. It uses the parton-shower approach for initial- and final-state QCD radiation, including colour coherence effects and azimuthal correlations both within and between jets. This article updates the description of HERWIG published in 1992, emphasising the new features incorporated since then. These include, in particular, the matching of first-order matrix elements with parton showers, a more correct treatment of heavy quark decays, and a wide range of new processes, including many predicted by the Minimal Supersymmetric Standard Model, with the option of R-parity violation. At the same time we offer a brief review of the physics underlying HERWIG, together with details of the input and control parameters and the output data, to provide a self-contained guide for prospective users of the program.

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HERWIG 6: an event generator for hadron emission reactions with interfering gluons (including supersymmetric processes)

HERWIG is a general-purpose Monte Carlo event generator, which includes the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron scattering and soft hadron-hadron collisions in one package. It uses the parton-shower approach for initial- and final-state QCD radiation, including colour coherence effects and azimuthal correlations both within and between jets. This article updates the description of HERWIG published in 1992, emphasising the new features incorporated since then. These include, in particular, the matching of first-order matrix elements with parton showers, a more correct treatment of heavy quark decays, and a wide range of new processes, including many predicted by the Minimal Supersymmetric Standard Model, with the option of R-parity violation. At the same time we offer a brief review of the physics underlying HERWIG together with details of the input and control parameters and the output data, to provide a self-contained guide for prospective users of the program. This version of the manual (version 3) is updated to HERWIG version 6.5, which is expected to be the last major release of Fortran HERWIG. Future developments will be implemented in a new C++ event generator, HERWIG++.

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HERWIG 6.5: an event generator for Hadron Emission Reactions With Interfering Gluons (including supersymmetric processes)

HERWIG 5.1 - a Monte Carlo event generator for simulating hadron emission reactions with interfering gluons

SuSpect: A Fortran code for the supersymmetric and Higgs particle spectrum in the MSSM

Phenomenological consequences of N = 1 supergravity theories with non-minimal kinetic energy terms for vector superfields

Intermediate-scale symmetry breaking and the spectrum of superpartners in superstring inspired supergravity models

We presentQ2-dependent parametrizations for the parton distributions within real photons obtained from full solutions of the corresponding leading order evolution equations. We show that our results differ appreciably from fits of the “asymptotic” solutions. Furthermore we discuss the production of heavy quarks as well as squarks and gluinos at the HERA collider using our parametrizations. The production rates are very promising especially in the case of gluino production.

Parametrizations of the photon structure and applications to supersymmetric particle production at HERA

A new class of false vacua in low energy N = 1 supergravity theories

N=1 supergravity theories with noncanonical kinetic energy terms for vector as well as chiral superfields are investigated. It is shown that, in general, no relation exists among the various soft-breaking parameters at the large scale. Nevertheless the gluino cannot be much heavier than scalar quarks of the first two generations due to renormalization effects. An explicit SU(5) model is constructed where both supergravity and SU(5) are broken by the help of a 24. While ${\mathrm{sin}}^{2}$${\mathrm{theta}}_{\mathrm{W}}$ and ${m}_{b}$/${m}_{\ensuremath{\tau}}$ can no longer be predicted, models of this type contain an additional ``light'' SU(3) octet, an SU(2) triplet, and a singlet, which might be, however, as heavy as ${10}^{7}$ GeV. Some general constraints on masses of superpartners are derived from the requirement of a gauge hierarchy stable against radiative corrections. Finally the possible relevance of these types of models for cosmological considerations is pointed out.

M. Drees

Papers

Phenomenological consequences of N = 1 supergravity theories with non-minimal kinetic energy terms for vector superfields

Intermediate-scale symmetry breaking and the spectrum of superpartners in superstring inspired supergravity models

Parametrizations of the photon structure and applications to supersymmetric particle production at HERA

A new class of false vacua in low energy N = 1 supergravity theories

N=1 supergravity grand unified theories with noncanonical kinetic energy terms