•  ATLAS-CMS correlations have been studied in Run 1, but it was mainly indicated for single observables (i.e. not differential):
  https://cds.cern.ch/record/2104039/files/JME-15-001-pas.pdf
• Should try to re-start discussion for 13 TeV, it could be a ~1year effort
• Everybody agrees that we should have a dedicated session about correlations in the LHC SM WG General meeting that will be held at CERN on the days 30th March to 1st April