JJet et PPlus lus TTracksracksSub-group of JetMET:Sub-group of JetMET:

RDMS members: I. Vardanyan, N. Ilina,RDMS members: I. Vardanyan, N. Ilina,O. Kodolova, A. Nikitenko (convener)O. Kodolova, A. Nikitenko (convener)

A. Nikitenko (IC/ITEP), RDMS meeting, March.2009

AN 2009-031, PAS JME-09-002

Jet+tracks algorithmJet+tracks algorithm

=0.5=0.5

The goal of algorithm: correct calorimeter jet energy to the energy of particles at vertex. out-of-calo-cone track in-calo-cone track

Basic algorithm steps:Basic algorithm steps:0. ZSP and PU off-set corr.0. ZSP and PU off-set corr.1.1. Subtract average expected Subtract average expected response of “in-calo-cone” response of “in-calo-cone” tracks from calo jet energy tracks from calo jet energy and add track momentum and add track momentum 2.2. Add momentum of “out-of-cone”Add momentum of “out-of-cone” trackstracks

Jet axis

Step 0: ZSP corrections

To be extracted from non ZSP data using single jet triggers

Step 1: correction for response of in-calo-cone tracks

EJet = EJetcalo – <Etrk

calo> + ptrk ,

<Etrkcalo> from data without ZSP

Response of pions from TB06Response of pions from TB06no zero suppressionno zero suppression

In-calo-cone tracks corrections In-calo-cone tracks corrections with TB “jets”with TB “jets”

Jet was formed from chargedpions (-) randomly selected from the data. Number of pions in jet is fixed:

jet consists of 6 pions of 2 GeV4 pions of 3 GeV2 pion of 4 GeV1 pion of 5 GeV

thus true jet energy is 37 GeV

Average particle response(see previous slide) wassubtracted from jet raw energyand replaced by track momentum

Single particle response: effect of ZSP (MC study)

Input to JPT: non ZSP response of single pions

Effect of ZSP on single pion response

Step 2: adding out-of-calo-cone tracks

EJet = EJet+ ptrk (trks 1,2,3 in fig)

Steps 0-2 in one plot

Take into accountTake into account tracker inefficiency (I) tracker inefficiency (I)

Ein-cone = ntrkin-cone(pT

bin, bin) x (1-trk)/trk x (<pbin> - <Ecalo>)

Eout-of-cone = ntrkout-of-cone(pT

bin, bin) x (1-trk)/trk x <pbin>

trk = F(pTbin, bin) – track finding efficiency

Jet Energy Scale andJet Energy Scale and tracker inefficiency tracker inefficiency

JES uncertainty due to single particle response

Performance for |Performance for ||<1.4|<1.4 Jet Enery Scale ET

reco / ETgen

Resolution:(ET

reco / ETgen)/(ET

reco / ETgen)

Performance for 1.4<|Performance for 1.4<||<2.0|<2.0 Jet Enery Scale ET

reco / ETgen

Resolution:(ET

reco / ETgen)/(ET

reco / ETgen)

Current JES vs Current JES vs

Still need to take intoaccount ECAL crystal calibration and more accurate response function

Calo vs Calo vs PF vs JPTPF vs JPT

Performance in CMSSW_2_2_3,full sim. after L2L3 corrections;“Official” JetMET plot

Latest PF improvements for 31Xvs JPT and calo in 2_2_3(see more in Michele’s talk)

Plot provided by P. Janot, no L2L3 corrections applied

ET >40 GeV, barrel

ET> 40 GeV, barrel

Work in progress to improve Work in progress to improve JPT for 31X releasesJPT for 31X releases

It was Monte-Carlo.It was Monte-Carlo.

Need time to commission JPT using Need time to commission JPT using real data: ZSP, single particle real data: ZSP, single particle

response, tracker efficiency from data; response, tracker efficiency from data;

tcMETtcMET = MET(corrected for MET(corrected for )) – pp + 〈〈 EE 〉〉(Replacing expected calorimeter responseexpected calorimeter response with track momentumtrack momentum)

Frank Golf et al.

CMSSW_1_6_XCMSSW_1_6_XCMSSW_1_6_XCMSSW_1_6_X

# of evts with MET>30 GeV (in Z’s) faked by detector resolution and other effects: reduced by factor ~3, while # of W’s almost unaffected as expected.# of evts with MET>30 GeV (in Z’s) faked by detector resolution and other effects: reduced by factor ~3, while # of W’s almost unaffected as expected.

METtcMET

Missing Energy (GeV)

2.5)&GeV 20(

2)N(DY

T

p

Z/*

N(MET>30) ≈ 3 3 N(tcMET>30)

Case where we don’t expect MET …

2.5)&GeV 20(

1)N(T

p

W

Missing Energy (GeV)

N(MET>30) ≈ N(tcMET>30)

Case where we have true MET …

Track-corrected METTrack-corrected MET

Jan 19, 2009Meeting with LHCC referees

18

Performance for |Performance for ||<1.4|<1.4 Jet Enery Scale ET

reco / ETgen

Resolution:(ET

reco / ETgen)/(ET

reco / ETgen)

ZSP corrections: corrections for zero suppression on calo sells