E. Soldatov03.11.2011 Tight photon efficiency study using radiative Z decays (update) E.Yu.Soldatov 1, 1 National Research Nuclear University “MEPhI” Outline:

E. Soldatov 03.11.2011

Tight photon efficiency study using radiativeTight photon efficiency study using radiative ZZ decaydecays (update)s (update)

E.Yu.Soldatov1, 1 National Research Nuclear University “MEPhI”

Outline:

1. Motivation

2. Selection

3. Data driven efficiency vs MC fudge factor corrected

4. Shower shape variables difference

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IntroductionIntroduction

What do we want?The main idea is to obtain a photon sample with maximum

purity with the method decoupled from the standard analysis methods.

Why do we want this?Studies of the ATLAS detector performance with tagged photons and first of all study and optimization of the tight cut criteria.

Very important for analysis all photon containing processes.

The best source of such kind of photons is a production of FSR photons from Z-lepton decay:

№ 2

2010 results of this study gave first evaluations on tight efficiency from Z radiative decays: https://indico.cern.ch/getFile.py/access?contribId=7&resId=1&materialId=slides&confId=125163

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Introduction: SamplesIntroduction: Samples

Electron channel:MC: mc10_7TeV.106046.PythiaZee_no_filter.merge.AOD.e574_s933_s946_r2399_r2300/Data: 2011 Periods D-H (Egamma stream) – 1.0 fb-1 (rel. 16 prod.)GRL: data11_7TeV.periodAllYear_DetStatus-v28-pro08-07_CoolRunQuery-00-04-00_Eg_standard.xml

Muon channel:MC: mc10_7TeV.106047.PythiaZmumu_no_filter.merge.AOD.e574_s933_s946_r2399_r2300/Data: 2011 Periods D-H (Muons stream) – 1.0 fb-1 (rel. 16 prod.)GRL: data11_7TeV.periodAllYear_DetStatus-v28-pro08-07_CoolRunQuery-00-04-00_WZjets_allchannels.xml


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Introduction: PreselectionIntroduction: Preselection

The initial requirements are: •Trigger for Zee:EF_e20_mediumTrigger for Z:EF_mu18_MG || EF_mu40_MSonly_barrel

First primary vertex with at least 3 tracks•ET>5 GeV for photons, •PT>15 GeV for electrons and muons, •||<2.47 (||<2.4 for muons); excluding the crack region (1.37<||<1.52),•Good object quality•D0-to-PV and Z0-to-PV cuts (EPS)•Electrons pass Medium cut•deltaR(l)>0.2&& preselection for leptons consistent with EPS recommendations applied

MCTruthClassifier Tool used for truth matching


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Introduction: SelectionIntroduction: Selection

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1. Mass of two leptons should have a missing part e.g. < Z bozon mass For electron channel 60 < m(ee) < 83 GeV, and for muon channel 40 < m() < 82 GeV

A kinematic approach of the photon selection

2. And 3 body mass should correspond to a mass of Z bozonFor electron channel 80 < m(ee)< 94 GeV and for muon channel 81 < m() < 95 GeV

Kinematics approach is based on a simple criteria of the event selection.

Three body mass spectrum (Zll)

3. Isolation: Etcone20_ptcorrected<5 GeV && Nucone20=0.

Signal (FSR)

Background (Jets, Brem, ISR)

(More detailed cut study: https://indico.cern.ch/getFile.py/access?contribId=3&resId=1&materialId=slides&confId=92681)


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TightTight cut efficiency studycut efficiency studyComparision of data driven efficiency vs fudge factor corrected MC

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Zee Zcombined


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TightTight cut efficiency studycut efficiency studyComparision of shower shape variables distributions

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R_eta

Difference in tail

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Z

R_phi

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DeltaE

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Eratio

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fside

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R_had

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R_had1

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Z

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W1

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weta2

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ConclusionsConclusions

Efficiency study for data periods D-H (release 16) ~1 fb-1 and mc10b using radiative Z decays (to electron and to muon channel) has been done.

Comparison between electron and muon channel has been shown. It has just some differencies in the areas with the low statistics.

Preliminar comparison of the data driven efficiency and fudge factor corrected MC has been presented.

Shower shapes variables differencies has been presented.

Any suggestions?

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Back-up slidesBack-up slides

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TightTight cut efficiency studycut efficiency studyComparison of the efficiency electrons and muons channels

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converted unconverted


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converted unconverted

Z

Z

Zee

Zee


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Barrel EndCapZ


Documents

E. Soldatov03.11.2011 Tight photon efficiency study using radiative Z decays (update) E.Yu.Soldatov 1, 1 National Research Nuclear University “MEPhI” Outline: