muons in MET

[Jessica Metcalfe]

Hi,

I read the documentation for the missing ET. From the documentation, it sounds like the MET calculation only uses calorimeter energies and no correction for the muons. However, when I look at the MET for a same-sign WW scattering event with two high pT (>25 GeV) muons, I would expect the MET to be very different for ee and mumu channels if electron energies are counted and muons not for the MET calculation. I am using a slightly modified (for the upgrade) version of the delphes ATLAS card. I've attached a plot of the MET for the different channels (one normalized, one not). Can you please clarify how the MET is calculated?

I am also wondering about the lepton isolation. Does it use track and calo info in the isolation calculation, and if so, does it take into account possible double counting from something like a charged pion that has a track and deposits in the calorimeter?

Thanks a lot for your help!
Cheers,
Jessica

[Michele Selvaggi]

Hi Jessica,

sorry for the late answer. The MET you are using is corrected for muons in some sense, since you are using all particle flow objects to compute it. If you don't want that you can change the input to the met calculation into (l.576)

add InputArray Calorimeter/towers

For the isolation, you are also using particle-flow, which is a combination of tracks and tower.
So to answer your question there should be no double counting as, in particle-flow, if a charged pion is found matching the hadronic tower, the hadronic tower is discounted (actually the difference in energy between them).

Hope this answers your questions,
Michele