image/svg+xml reader electrons propagated stable particles muons ε unique object finder electrons photons jets muons MET LHEF Pythia8 ProMC FastJet particle propagator pile-up merger Pile-upfile ROOT Analysismacros Eventdisplay LHCO merger pile-up subtractors b-, τ-tagging energy scale isolation Configfile photons towers and tracks calorimeter and energy flow σ HepMC StdHEP(XDR) ε ε