Can I use the LHE file from Pythia as input to detector simulation?

No! The file pythia_events.lhe contains a simplified version of the Pythia output, with simple jet clustering performed. It is only meant as a resource to allow easy comparison between parton level, hadron level and detector level observables. The main program, hep2lhe.f (in pythia-pgs/src), can also be used as a template for direct analysis of the Pythia STDHEP output.

Only the file pythia_events.hep should be used as input to detector simulators such as PGS and Delphes.

-- Main.JohanAlwall - 2010-03-07