PHOJET Home Page


General information

Program name:
PHOJET
Current version:
1.10 from Dec. 4th, 1997
Program size:
about 38.000 lines
Author:
Ralph Engel
email:
Ralph.Engel(at)ik.fzk.de

An update to run the program with the Glück-Reya-Stratmann photon PDF parametrizations (Phys. Rev. D51 (1995) 3220 and references therein) can be found here.

Short writeup

Purpose

The Monte Carlo (MC) event generator PHOJET can be used to simulate hadronic multiparticle production at high energies for hadron-hadron, photon-hadron, and photon-photon interactions (hadron = proton, antiproton, neutron, or pion). The generator includes the photon flux simulation for photon-hadron and photon-photon processes in lepton-lepton, lepton-hadron, and heavy ion-heavy ion collisions. In addition, various photon flux spectra of relevance to planned linear colliders are implemented (bremsstrahlung, beamstrahlung, laser-backscattering).

In order to simulate hadron and jet production in photon-nucleus or lepton-nucleus collisions for real and weakly-virtual photons the MC event generator DPMJET-III can be used. DPMJET-III is based on the Gribov-Gauber model of high-energy hadron-nucleus and nucleus-nucleus collisions and incorporates an interface to PHOJET.

Physics

The ideas and methods used in the program are based mainly on the Dual Parton Model (DPM). In order to combine the DPM on soft processes with the predictive power of perturbative QCD, the event generator is formulated as a two-component model (soft and hard component).

On the basis of the optical theorem, Regge phenomenology is used to parametrize the total and elastic cross sections as well as a series of partial inelastic cross sections. In order to preseve s-channel unitarity, Gribov's Reggeon calculus is applied. Consequently, the model predicts so called "multiple parton interactions" in one event. Since the unitarization of soft and hard processes is treated in unified way, multiple soft and hard interactions may be generated in one event.

Hard scattering processes are simulated using lowest-order perturbative QCD. Initial state and final state parton showers are generated in leading-log approximation. Some coherence effects (angular ordering in the emissions) are taken into account.

For the fragmentation of the parton configurations, the Lund program JETSET is used.

Concerning many aspects of the program, the realization of DPM is similar to the MC event generator DTUJET-93 simulating multiparticle production in proton-proton and proton-anitproton collisions up to very high energies.

A detailed description of the physics in PHOJET and various applications of this generator can be found in the thesis of the author.

Program code

Currently, the PHOJET program can be obtained by e-mail request from the author or via download of the compressed tar archive (version 1.05c, 1.10). If you send an email to the author you will get informed regularly about bug-fixes and updates.

User manual

See also the publications listed at the end of this page.

Some changes between version 1.05c and 1.10 are described here.

Examples how to use the program

Here, we give the input cards for needed to run the program (versions 1.04 and 1.05) for various experimental setups. It is important to ensure that the program can read the file fitpar.dat to initialize the model parameters correctly.

Parameter tuning

To simplify the model tuning, a short summary of some important program switches and parameters has been collected.

Related publications

In the following, some publications related to the Dual Parton Model and the implementation of this model in the PHOJET event generator are collected.