gibuu is hosted by Hepforge, IPPP Durham

The GiBUU project

The GiBUU project provides a unified theory and transport framework in the MeV and GeV energy regimes for

  • elementary reactions on nuclei, as e.g.
    • electron + A,
    • photon + A,
    • neutrino + A ,
    • hadron + A (especially pion + A and proton + A)
  • and for A + A heavy-ion collisions,

using the same physics input and code. The GiBUU code provides a full dynamical description of the reaction and delivers the complete final state of an event; it can thus be used as an event generator. The source code is freely available.

For all the reactions, the flow of particles is modeled within a Boltzmann-Uehling-Uhlenbeck (BUU) framework. The relevant degrees of freedom are mesons and baryons, which propagate in mean fields and scatter according to cross sections which are applicable to the energy range of a few 10 MeV to about 40 GeV. In the higher energy regimes the concept of pre-hadronic interactions is implemented in order to realize color transparency and formation time effects. For a general overview of the model, its theoretical basis as well as many practical details, refer to the review paper:

Transport-theoretical Description of Nuclear Reactions
O. Buss, T. Gaitanos, K. Gallmeister, H. van Hees, M. Kaskulov, O. Lalakulich, A. B. Larionov, T. Leitner, J. Weil, U. Mosel
Phys. Rept. 512 (2012) 1-124 / Inspire

The numerical implementation, named GiBUU (aka The Giessen BUU Project), is written in modular Fortran 2003 and based upon a Subversion version control system, which allows for a concise control over the full development phase of the code.

The history of the code is rather long and reports about several main development steps. The present initiative accomplished a total rewrite of the source code in a present-day computing language. The main goals of this effort were modularization to allow for a more transparent multi-user development process, a strict reduction of global variables for a more transparent debugging procedure, an improved control over the development phase such that modifications can be backtracked and a unified standard version. Therefore every member of the team works on the same single code version, albeit different temporal branches may coexist. Possible technical overhead is compensated by the benefit of a faster distribution of improvements and innovations and their enhanced sustainability.

GiBUU is being developed by a collaboration of people at different institutes:


  • 31. Aug. 2023: GiBUU 2023 has been released.
    • new elementary e+N and nu+N prescription according Christy-Bosted fits when using 'initNeutrino' (for details see
      main switch new_eN in namelist 'nl_neweN'
    • OutChannels-Analysis also for events when using 'initNeutrino'
    • improve resonance production in lowPhoton/Electron in RMF mode
    • tachyons removed in RMF mode
    • number of ensembles<100 need to be enforced by a minus sign in the jobcard
    • "equal weights mode" for events using the 'HiLepton' init
    • bugfix for detailed balance in n pi+ <-> p pi0
    • modifications for newest compiler versions
    • (huge) refactoring, cosmetics, renaming and minor bug fixes

General Info

The GiBUU Model

The GiBUU Team

Using GiBUU


About GiBUU

External Projects


For Developers


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Last modified 9 days ago Last modified on Nov 22, 2023, 8:43:48 PM