Various progress in Z µ + µ -

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Various progress in Z µ + µ -. EWK Dilepton meeting, 23.11.2010 Arie Bodek, Yeonsei Chung, Jiyeon Han Rochester University Alessio Bonato, Andrei Gritsan, Zijin Guo, Nhan Tran* Johns Hopkins University. Outline. A first look at MC and Data in CMS Features, comparison, implications - PowerPoint PPT Presentation

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Various progress in Zµ+µ-

EWK Dilepton meeting, 23.11.2010

Arie Bodek, Yeonsei Chung, Jiyeon Han Rochester University

Alessio Bonato, Andrei Gritsan, Zijin Guo, Nhan Tran*

Johns Hopkins University

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Outline

• A first look at MC and Data in CMS• Features, comparison, implications

• Implications for analyses of Afb and sin2W• Plans and progress in Afb with event weighting

http://indico.cern.ch/conferenceDisplay.py?confId=112949 (N.T.)

• Plans and progress in sin2W with likelihood methodhttp://indico.cern.ch/conferenceDisplay.py?confId=113453 (A.

Gritsan)

A report on various activities related to Zµ+µ-

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Data/MC: Kinematic distributions

MC: /DYToMuMu_M-20_CT10_TuneZ2_7TeV-powheg-pythia/Fall10-START38_V12-v1

data: 35 pb-1

Basic plots match those shown elsewhere with reasonable agreement

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More MC plots

Interesting acceptance effect

resolutionresolution vs. eta

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Afb in MC

Full Y range 1 < |Y| < 2

Effect seen last time…

Forward-backward asymmetry switches sign near Z peakMore severe at greater Y

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Resolution and binningLet’s look at one specific mass bin…

Resolution with right-side tail, “artificial” due to binning

Reason for Afb sign flip

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Implications for event weighting Afb

• Resolution/FSR and bin migration effects large (could increase bin size)

• Solution: need to account for by including in weighting tables; FSR and “fast smear” at generator level, need to implement negative weighting

raw Afb

Event weighting for

dilution

weighted Afb

Pull corrections for

detector effects

measured Afb

raw Afb

Event weighting for dilution,

FSR, resolution

weighted Afb

Pull corrections for

remaining effects

measured Afb

Reminder of the strategy:

Change strategy:

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ResolutionResolution effects need to be understood for both likelihood technique (resolution convolution) and event weighting technique

(fast smear for weighting)

Fit with double Gaussian for both m and m2

resolution - technical reasons due to analytical convolution in likelihood

approach

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AcceptanceFlat acceptance not a good model, lose events

at larger Gen level (flat acceptance, ||<2.1), Reco level (||<2.1)

Parametrize acceptance with polynomial fit (acceptance function)

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Implication for likelihood analysis

• Recall, likelihood function over 3 observables (m,Y,cos) used in angular analysis and fitting of Weinberg angle, sin2W.

• Analytical description involving• Parton-level cross-section• Parton distribution functions• Dilution• Acceptance - flat acceptance• Resolution - Gaussian smearing (No FSR)

• Implement more realistic modeling of detector effects using MC for acceptance and resolution

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Resolution and acceptance

1D projections with flat acceptance and Gaussian smearing

Now, implementing realistic resolution and acceptance

*Fit under study

Y mcos

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