Some MET studies Some MET studies

Niels van Eldik and Peter Kluit

29 May 2013

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IntroductionIntroduction

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Data set used for studies:mc12_8TeV.147807.PowhegPythia8_AU2CT10_Zmumu.merge.AOD.e1169_s1469_s1470_r3542_r3549Two methods:-MET from AOD directly using the LocHadTopo and Muon corrections. Standard “out-of-the-box” for Staco and Muid.

- MET using LocHadTopo recalculated for the muon term using:- Staco: all loose muons (CB+Tagged)- Muon: medium muons with additional momentum balance cut

- CB muons (no tagged muons)- SA muons for |eta|>2.0 with inner station on track

- All CB/Tag muons (for Muon or Staco) should pass the ID MCP selectionUse for muon term (Staco/Muon): Sum p(vertex)-Eloss“Idea is that badly reconstructed muons give MET tails”

Plots are shown for two and one muon (with the above selection)

Standard “out of the box” Standard “out of the box” METMET

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Observe less tails in Muid than Staco

But let’s look at the new recalculated MET

Recalculated MET for Recalculated MET for MuonsMuons

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Also here we observe less tails in Muid than Staco

Now look at 1 muons…

Recalculated MET for MuonsRecalculated MET for Muonsonly one muon foundonly one muon found

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This MUST

give MET because the muon was not taken into account

How important is this?

Recalculated MET for MuonsRecalculated MET for Muonsonly one muon foundonly one muon found

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How important is this?

If one includes the one muon found one observes that the dominant tail is from one muon.

So one has to be careful to remain consistent in the muon selection and the MET calculation.Inconsistencies can lead to large tails.

And… a missing high pT muon can give a substantial tail

Recalculated loose MET Recalculated loose MET

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bool muonOK = false; if(muon_isLoose>0&&muon_pt>2.5&&muon_p>4.) { if(muon_mu_cb>0) {// loose MCP ID selection if(muon_npixel+muon_nsct>5) muonOK = true;// keep tracklets if(fabs(muon_eta)>2.0&&muon_npixel>3&&muon_nin>2) muonOK = true; } else if (muon_mu_tag>0) {// loose MCP ID selection if(muon_npixel+muon_nsct>5) muonOK = true; } else if (muon_mu_sa>0) {// loose Muon SA selection; require inner station precision hits (CSC/MDT) if(fabs(muon_eta)>2.5&&muon_nin>2) muonOK = true; } }

The selection has the feature that it keeps the CB muons that have only a tracklet in the ID (this would have 4 pixel hits and no SCT hits and fail the nsilicon > 5 cut). I don't know whether the number of muon precision hits in the inner station (muon_nin) is stored on the D3PD. One could then replace this cut by requiring isMedium.

Here I did not yet add the Calorimeter muons around eta=0. It is rather close to what is done for Muid in the AOD.

Recalculated loose MET Recalculated loose MET

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Loose MET is similar to MET ‘medium’ muons

But has a big advantage…One can use loose muons

Recalculated loose MET Recalculated loose MET

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Now selection loose muons…

MET loose has tails that are OK.MET ‘medium’ has tail…. due inconsistent muon/MET selection

For the MET one can apply a loose selection to match also analyses that do not apply strict requirements on all muons.One can think e.g. of the H -> 4 muon analysis where CB+Tagged+SA muons are used.