The idea under this clustering algorithm is based on the topological development of hadronic showers in high granularity sampling calorimeters follows an oriented-tree structure. The goal of this algorithm is to use the energy deposits in calorimeters as vertexes to connect and thus create an oriented tree-topology, in the sense of the graph theory. The implementation do not depend on any event data model since the use of the PandoraSDK framework. This library can be used by any experiment in high energy physics if the detector granularity allows it.

The project is composed of the following libraries :

• ArborContent : The algorithms implementation using the PandoraSDK framework
• MarlinArbor : the Marlin interface that loads and runs the algorithms (require ILCSOFT)
• ArborPFA : the installation package

The project was initiated by Henri Videau for the ALEPH experiment and then adapted by Manqi Ruan for the ILC project.

All packages are free and open source, released under the GPL license.