Partial Wave Analysis

To perform sophisticated analyses in the field of hadron spectroscopy we employ techniques of amplitude analysis and partial wave decomposition of the recorded data. Various analyses are ongoing, mostly of charmonium decays using data recorded by the BESIII experiment, antiproton-proton annihilation data recorded by the CrystalBarrel experiment at CERN or antiproton-proton simulation studies for the upcoming PANDA experiment at FAIR.

A dedicated software package for partial wave analysis is being developed at our institute.

PAWIAN (PArtial Wave Interactive ANalysis)

PAWIAN is a powerful, user-friendly and highly modular partial wave analysis software package with the aim to support analyses for a multitude of different physics cases at hadron physics experiments. Real data originating from the pbar p annihilation process and from e+ e- reactions are currently under investigation with PAWIAN. It is possible to define complicated decay trees, to choose different spin formalisms and resonance dynamics as well as to set up numerous other parameters via a simple plain text configuration file without modifying and compiling any code.

Parameters that can be set in the configuration file include, among many more:

  • The amplitudes can be described with different formalisms.
    The widely-used helicity, canonical and the Lorentz-invariant Rarita-Schwinger formalisms are supported so far
  • A couple of different descriptions for the dynamics of resonances can be chosen, e.g. the Breit-Wigner parametrization with or without barrier factors, the Flatté-formalism and the K-matrix formalism
  • The minimization is realized with an event-based maximum likelihood fit. It makes use of the MINUIT2 minimization package. In addition one can start with a pre-fitter based on a genetic algorithm
  • To improve the performance for the very time-consuming fit procedure the applications can be run in parallel on multi-core CPUs (multi-threading) and/or on computer clusters (networking)
  • Coupled channel analyses are supported
  • The analyst can generate events based on the user-defined decay model or on the fit result obtained with real data
  • Tools for quality assurance, histogramming and for extracting values of different goodness-of-fit criteria are also available

PAWIAN is written in C++ and follows an object-oriented approach with a wide range of flexibility. The code therefore allows to be easily extended for further decay models, complete amplitudes and also another descriptions for the dynamics.

PAWIAN and all its associated files are licensed under the GNU General Public License v3 (GPLv3), which you can find here or in the COPYING file in the PAWIAN root directory.

 

How to get PAWIAN?

You can obtain a copy of the PAWIAN source code via git. Our repository is hosted here:

https://jollyj.ep1.rub.de/EP1/Pawian

Feel free to create a user account for our gitlab server and clone the PAWIAN project, or contact us directly for questions concerning the software (Contact: email hidden; JavaScript is required) or the repository (Contact: email hidden; JavaScript is required)!