  At the CHEP03 conference we launched the Physics Analysis eXpert (PAX), a C++
toolkit released for the use in advanced high energy physics (HEP) analyses.
This toolkit allows to define a level of abstraction beyond detector
reconstruction by providing a general, persistent container model for HEP
events. Physics objects such as particles, vertices and collisions can easily
be stored, accessed and manipulated. Bookkeeping of relations between these
objects (like decay trees, vertex and collision separation, etc.) including
deep copies is fully provided by the relation management. Event container and
associated objects represent a uniform interface for algorithms and facilitate
the parallel development and evaluation of different physics interpretations of
individual events. So-called analysis factories, which actively identify and
distinguish different physics processes and study systematic uncertainties, can
easily be realized with the PAX toolkit.
  PAX is officially released to experiments at Tevatron and LHC. Being explored
by a growing user community, it is applied in a number of complex physics
analyses, two of which are presented here. We report the successful application
in studies of t-tbar production at the Tevatron and Higgs searches in the
channel t-tbar-Higgs at the LHC and give a short outlook on further
developments.
