PAWIAN PWA Software

Introduction

PAWIAN (PArtial Wave Interactive ANalysis Software) is a partial wave analysis software package with the aim to support analyses dedicated to the physics cases at P̅ANDA and partly other hadron spectroscopy experiments. Real data from p̅ p and e⁺ e^- annihilations, from γ γ fusion and from ππ and πp scattering processes are currently under investigation with PAWIAN. Diverse parts of the powerful, user-friendly and highly modular software are available. It is possible to define complicated decay trees, to choose between different dynamical descriptions as well as to set up numerous other settings via a simple configuration file, without modifying and compiling any code. The key features of PAWIAN, which can be setup via such a configuration file with a user-friendly syntax, are as follows:

• The amplitudes can be described with different formalisms. The widely-used helicity and partly the Lorentz-invariant Rarita-Schwinger formalisms are supported so far.
• Various different descriptions of the dynamics can be selected which are among others the well-known Breit-Wigner parametrization with or without barrier factors, the Flatté-formalism and the K-matrix formalism by taking into account the fundamental constraints of unitarity and analyticity in an adequate way.
• The minimization is performed in an event-based maximum likelihood fit using the MINUIT2 minimization package. In addition one can start with a pre-fitter based on genetic algorithms.
• To improve the performance for the very time-consuming fit procedure, the applications can be run in parallel in a server-client mode on e.g. computer clusters.
• Coupled channel analyses are supported.
• The analyst can generate events based on the user-defined decay model or a 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.
• Tools for extracting physical quantities like pole positions or coupling strengths for the production and the decay

PAWIAN is written in C++ and follows an object-oriented approach with a wide range of flexibility. The software code therefore allows to easily add further decay models, complete amplitudes and other dynamical descriptions.

Documentation

• First step instructions

• Examples and Tutorials
  Example: PWA for pp reactions

• Parser arguments

• Execution modes

• Set-up of the dynamics

Outcome of the PAWIAN Activities