Status of Geant4 hadronic physics for the simulation of LHC experiments at the start of LHC physics program

In this short note we summarize the status of Geant4 hadronic physics for the simulation of LHC experiments, based on an extended physics validation program carried out in the last ten years. The data used come from thintarget published results and LHC test-beam set-ups with electron, pion and proton beams. No LHC collider data are yet utilized; rather, the expectations for the physics quality of Geant4 hadronic simulations for the first analyses at the start of the LHC physics program are discussed. Several physics lists are considered, for Geant4 versions 9.2 (used currently in ATLAS, CMS and LHCb simulations) and 9.3 (latest version, released in December 2009).