General searches are based on the InvMass program
https://atlaswww.hep.anl.gov/asc/WebSVN/listing.php?repname=InvMass
The description of this program is given in ATL-COM-PHYS-2009-619 (General searches for new particles by J. Boomsma and S. Chekanov.
The input of this program is based on ROOT format bases on “LParticle” class (extension of the TLorenzVector). This format cna be generated using either D3PD, AOD or ESD. Example of such program for convertion from the AOD/ESD format is given in
https://atlaswww.hep.anl.gov/asc/WebSVN/listing.php?repname=NtupleMaker
A typical size of the converted AOD/D3PD is close to several GB for each 100 pb-1 (the Egamma stream).
The last processed data corresponds to 200 pb-1 using the Egamma stream.
The link https://twiki.cern.ch/twiki/bin/view/AtlasProtected/GeneralSearches
Contains the most recent ROOT file with the invariant masses