t t production with N-jets and with jet vetoes at CMS Carmen Diez - - PowerPoint PPT Presentation

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t t production with N-jets and with jet vetoes at CMS Carmen Diez - - PowerPoint PPT Presentation

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t t production with N-jets and with jet vetoes at CMS Carmen Diez Pardos for the CMS collaboration DESY JetLHC2014: Workshop on Jet Vetoes and Jet Multiplicity Observables at the LHC, 16-18 July 2014 IPPP Durham Outline Introduction 1

slide-1
SLIDE 1

t¯ t production with N-jets and with jet vetoes at CMS

Carmen Diez Pardos for the CMS collaboration

DESY

JetLHC2014: Workshop on Jet Vetoes and Jet Multiplicity Observables at the LHC, 16-18 July 2014 IPPP Durham

slide-2
SLIDE 2

Outline

1

Introduction

2

Normalised differential σt¯

t as a function of N Jets 3

σt¯

t as a function of N additional jets 4

Kinematic distributions for the leading pT additional jets

5

Veto on additional jets

6

Summary

[pb] σ Production Cross Section,

  • 1

10 1 10

2

10

3

10

4

10

5

10

CMS Preliminary

Feb 2014

W n jet(s) ≥ Z n jet(s) ≥ γ W γ Z WW WZ ZZ WW → γ γ qqll EW γ WV tt =n jet(s) t-ch t tW s-ch t γ tt ttZ σ ∆ in exp. H σ ∆ Th. ggH qqH VBF VH ttH

CMS 95%CL limit )

  • 1

5.0 fb ≤ 7 TeV CMS measurement (L )

  • 1

19.6 fb ≤ 8 TeV CMS measurement (L 7 TeV Theory prediction 8 TeV Theory prediction

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 2/42

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SLIDE 3

Introduction

Motivation

At LHC energies, about half of t¯ t events are produced with additional hard jets (not coming from the t¯ t decay). Precise understanding of these events is important:

Test higher-order QCD predictions Anomalous production of t¯ t(+jets) could reveal new physics t¯ t+jets is a background for many searches and for t¯ tH

In general, sizeable uncertainty from QCD radiation for many top quark analysis

Theory predictions and models need to be tuned and tested with new measurements

Large samples of t¯ t events provide a great opportunity to study the details of the production mechanisms

Potential of constraining QCD radiation at the scale of the top quark mass

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 3/42

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SLIDE 4

Introduction

Top quark production and decay

t¯ t production mainly by gluon fusion at LHC (∼80% at 7-8 TeV) W decay defines final state: Semileptonic [e/µ]: BR∼30% and manageable BG (ie. W+jets) Dileptonic [e/µ]: BR∼5% and small BG (ie. DY+jets) All-jets: BR∼46% but largest BG (ie. QCD multijet) τ+jets: BR∼15%

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 4/42

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SLIDE 5

Introduction

Introduction

Present studies of t¯ t+jets with 7 TeV data, both in the dilepton and the lepton+jets channels, and 8 TeV data in the dilepton channels. Measurements performed:

⋄ Differential cross-section measurement in the dilepton and l+jets channels as a function of jet multiplicity ⋄ l+jets: t¯ t production as a function of the additional jet multiplicity. ⋄ dilepton: properties of additional jets, t¯ t production with a veto on additional jet activity.

− → Measurements in visible phase space, corrected to particle level. 7 TeV results: arXiv:1404.3171, submitted to EPJC (lepton+jets, dilepton channels) 8 TeV results: CMS-PAS-TOP-12-041 (dilepton channel)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 5/42

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SLIDE 6

Introduction

Generator setups for t¯ t at CMS

Matrix Element + Parton Shower generators Better description of high multiplicities Initial and final state radiation (ISR/FSR) modelling via ME from assumed Q2 variation Matching procedure to remove double counting between partons produced by ME and PS Next to Leading Order generators More accurate in normalisation Smaller uncertainty on Q2 Top mass: mt = 172.5 GeV

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 6/42

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SLIDE 7

Introduction

Radiative corrections

The Q2 scale variations address two aspects: renormalisation and factorisation scale (ME) amount of ISR/FSR For each event, Q2 is defined as: MadGraph: Q2 = m2

t + p2 T

Powheg/MC@NLO: Q2 = m2

t

Parton showering: shares Q2 factor αs with ME implicitely: starting scale changes with ∆Q2 MadGraph(+Pythia), the default MC, uses: tree-level diagrams for hard radiation and interferences (up to 3 final-state partons for t¯ t) parton showering for soft and collinear region (with Pythia 6.42X) matching with ktMLM (ensures smoothness of N→N+1 jet rates), thresholds varied by a factor 0.5 and 2.0 (nominal = 20 GeV) → Uncertainty on radiation covered by variations of Q2 and ME-PS matching

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 7/42

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SLIDE 8

Introduction

Event selection

Dilepton

1 Dilepton triggers 2 At least two isolated

leptons (pT > 20 GeV, |η| <2.4), opposite sign

3 ≥2 jets (anti-kT, R<0.5)

with pT > 30 GeV, |η| <2.4

4 QCD veto:

Mll > 12-20 GeV

5 In ee, µµ: Z veto

(76 < Mll <106 GeV), E miss

T

>30-40 GeV

6 At least one b-tagged jet

Lepton+jets

1 Single muon or

electron+jets trigger

2 One isolated lepton

(pT > 30 GeV, e: |η| <2.5, µ: |η| <2.1)

3 ≥3 jets (anti-kT, R<0.5)

with pT > 35 GeV, |η| <2.4 (≥4 jets with pT > 30 GeV - additional jet measurement)

4 Loose lepton veto in both

channels

5 At least two b-tagged jets

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 8/42

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SLIDE 9

Introduction

Selection and analysis strategy

Dilepton channels Event reconstruction: Kinematic reconstruction of the t¯ t system Background estimation: ⋄ Z/γ∗+jets estimated from data ⋄ Other BGs (single top, dibosons, etc) estimated from MC Lepton+jets channels Background estimation ⋄ W+jets estimated from data ⋄ QCD: data driven ⋄ Single top, Z/γ∗+jets and diboson are from MC → Signal: t¯ t MadGraph+Pythia (normalised to NNLO+NNLL)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 9/42

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SLIDE 10

Introduction

Control Plots: Reconstructed jet multiplicity

7 TeV, dilepton: pT >30 GeV, l+jets: pT >35 GeV

Dilepton l+jets

Events

  • 1

10 1 10

2

10

3

10

4

10

5

10

6

10

Data Signal t t Other t t Single t W+Jets µ µ ee/ → * γ Z / τ τ → * γ Z / Diboson QCD Multijet

Dilepton Combined = 7 TeV s at

  • 1

CMS, L = 5.0 fb

jets

N

2 3 4 5 6 7 8 ≥

Data/MC 0.5 1 1.5

Events 1 10

2

10

3

10

4

10

5

10

6

10

Data Signal t t Other t t Single t W+Jets *+Jets γ Z/ Diboson QCD Multijet

Lepton+Jets Combined = 7 TeV s at

  • 1

CMS, L = 5.0 fb

jets

N

3 4 5 6 7 8 ≥

Data/MC 0.5 1 1.5

Good description of data within uncertainties. (Similar description with 8 TeV data)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 10/42

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SLIDE 11

Cross Sections: NJets

Normalised differential cross sections

1 σt¯

t

dσi dNj = 1 σt¯

t

xi ∆i

X L

xi number of events after background subtraction, corrected for detector efficiencies, acceptances and migration to particle level (regularised unfolding). σt¯

t inclusive t¯

t cross section in the same phase space (visible). ∆X: bin width (=1) Measurement done in the visible phase space: pl

T >20(30) GeV, |ηµ| <2.4 (2.1) dilepton (l+jets), |ηe| <2.5

pjet

T >30(35) GeV dilepton (l+jets), |ηjet| <2.4, jets required ∆R(j, l) >0.4,

b-jets identified by B-hadron Comparing results to predictions from: Different generators (POWHEG+Pythia, MC@NLO+Herwig) MadGraph+Pythia with varied Q2 scale, matching threshold

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 11/42

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SLIDE 12

Cross Sections: NJets

Systematic uncertainties

Sources considered: Jet energy scale and resolution Background estimate Model uncertainties: Q2 scale (using samples with 2*Q, 0.5*Q), jet-parton matching threshold (threshold halved/doubled), hadronisation model, the color reconnection modelling and PDF Other sources: luminosity, pileup, b-tagging, lepton identification and trigger efficiencies Uncertainties determined individually for each bin. Normalised cross sections: bin-to-bin correlated uncertainties cancel (luminosity, flat SF, etc.), only shape uncertainties contribute (shape variation for b-tag, BG, scale, hadronisation etc.) Total syst. uncertainty varies from 3-6% in the low multiplicity bins to 20-30% for the highest multiplicities. Most important sources: JES and Q2 scale and ME/PS Matching

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 12/42

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SLIDE 13

Cross Sections: NJets

Normalised diff. σt¯

t as a function of NJets

Results 7 TeV: dilepton and l+jets channels

⋄ MadGraph+Pythia, POWHEG+Pythia provide a reasonable description ⋄ MC@NLO+Herwig doesn’t describe large jet multiplicities

2 3 4 5 6

jets

dN σ d σ 1

  • 3

10

  • 2

10

  • 1

10 1 = 7 TeV s at

  • 1

CMS, L = 5.0 fb Dilepton Combined Data MadGraph+Pythia MC@NLO+Herwig POWHEG+Pythia

jets

N

2 3 4 5 6 ≥ Data/MC

0.5 1 1.5

1 2 3 4 5

jets

dN σ d σ 1

  • 3

10

  • 2

10

  • 1

10 1 Data MadGraph+Pythia MC@NLO+Herwig POWHEG+Pythia = 7 TeV s at

  • 1

CMS, L = 5.0 fb Lepton+Jets Combined

jets

N

3 4 5 6 7 8 ≥ Data/MC

0.5 1 1.5

Results are consistent among channels (dilepton, l+jets)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 13/42

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SLIDE 14

Cross Sections: NJets

Normalised diff. σt¯

t as a function of NJets

Results 7 TeV: dilepton and l+jets channels

Comparison with MadGraph, varying Q2 scale and jet/parton matching threshold up and down

2 3 4 5 6

jets

dN σ d σ 1

  • 3

10

  • 2

10

  • 1

10 1 Data MadGraph+Pythia

2

= 4*Q

2 F

µ =

2 R

µ MadGraph /4

2

= Q

2 F

µ =

2 R

µ MadGraph MadGraph matching up MadGraph matching down = 7 TeV s at

  • 1

CMS, L = 5.0 fb Dilepton Combined

jets

N

2 3 4 5 6 ≥ Data/MC

0.5 1 1.5

1 2 3 4 5

jets

dN σ d σ 1

  • 3

10

  • 2

10

  • 1

10 1 Data MadGraph+Pythia

2

= 4*Q

2 F

µ =

2 R

µ MadGraph /4

2

= Q

2 F

µ =

2 R

µ MadGraph MadGraph matching up MadGraph matching down = 7 TeV s at

  • 1

CMS, L = 5.0 fb Lepton+Jets Combined

jets

N

3 4 5 6 7 8 ≥ Data/MC

0.5 1 1.5

⋄ Choice of lower scale gives slightly worse description of the data.

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 14/42

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SLIDE 15

Cross Sections: NJets

Normalised diff. σt¯

t as a function of NJets

Results 8 TeV: dilepton for jets pT > 60 GeV, pT > 100 GeV Larger data samples allow to measure higher pT ⋄ MadGraph+Pythia, POWHEG+Pythia provide a reasonable description, MC@NLO+Herwig describes data better for high jet-pT. ⋄ Choice of lower Q2 scale gives slightly worse description of the data. ⋄ Results consistent with 7 TeV measurement.

Jet pT > 60 GeV

dJets σ d σ 1

  • 3

10

  • 2

10

  • 1

10 1 10 = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined > 60 GeV

jet T

p Data MadGraph+Pythia MC@NLO+Herwig POWHEG+Pythia

Jets

1 2 3 4 5 6 ≥ Data/MC 0.5 1 1.5

dJets σ d σ 1

  • 3

10

  • 2

10

  • 1

10 1 10 = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined > 60 GeV

jet T

p Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down

Jets

1 2 3 4 5 6 ≥ Data/MC 0.5 1 1.5

Jet pT > 100 GeV

dJets σ d σ 1

  • 2

10

  • 1

10 1 10 = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined > 100 GeV

jet T

p Data MadGraph+Pythia MC@NLO+Herwig POWHEG+Pythia

Jets

1 2 3 4 ≥ Data/MC 0.5 1 1.5

dJets σ d σ 1

  • 2

10

  • 1

10 1 10 = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined > 100 GeV

jet T

p Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down

Jets

1 2 3 4 ≥ Data/MC 0.5 1 1.5
  • C. Diez Pardos (DESY)

Durham, 18 July 2014 15/42

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SLIDE 16

Cross Sections: Additional jets

Cross section as a function of the additional jet number

7 TeV: Lepton+jets channel

Categorise every t¯ t MC event as a function of the number of generated jets NOT matching any of top decay products (b quarks, light quarks and prompt lepton) Jets with ∆R >0.5: additional radiated jets → classification of events in t¯ t+0,1,≥2 additional jets Extracting rates of these t¯ t classes from data via a template fit Selection: similar to previous section, but selection events with at least 4 jets with pT > 30 GeV.

jets

N

4 5 6 7 8 ≥ Arbitrary units

0.1 0.2 0.3 0.4 0.5 0.6

+ 0 add. Jets t t + 1 add. Jet t t 2 add. Jets ≥ + t t Lepton+Jets Combined = 7 TeV s CMS Simulation at

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 16/42

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SLIDE 17

Cross Sections: Additional jets

Template fit results

Simultaneous fit to data in three jet multiplicity bins in e/µ+jets channels Templates built from smallest χ of any jet combination (using b-tag info) χ = mrec

W had − mtrue W had

σW had 2 + mrec

thad − mtrue thad

σthad 2 + mrec

tlep − mtrue tlep

σtlep 2 from full event reconstruction χ lower if all jets from the t¯ t decay are reconstructed

20 40 60 80 100 120 Events

1 10

2

10

3

10

4

10

= 7 TeV s at

  • 1

CMS, L = 5.0 fb

+ 0 add. Jets t t + 1 add. Jet t t 2 add. Jets ≥ + t t Data Single t W+Jets *+Jets γ Z/ QCD Multijet Diboson e + 4 Jets e + 5 Jets 6 Jets ≥ e + + 4 Jets µ + 5 Jets µ 6 Jets ≥ + µ 2

χ

Data/Fit 0.5 1 1.5 5 10 15 5 10 15 5 10 15 5 10 15 5 10 15 5 10 15 5 10 15 5 10 15 5 10 15 5 10 15 5 10 15 20 5 10 15 20

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 17/42

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SLIDE 18

Cross Sections: Additional jets

  • Diff. cross section: additional jet multiplicity

1 2

  • add. jets

dN σ d σ 1

0.1 0.2 0.3 0.4 0.5 Data MadGraph+Pythia MC@NLO+Herwig POWHEG+Pythia = 7 TeV s at

  • 1

CMS, L = 5.0 fb Lepton+Jets Combined

  • add. jets

N

1 2 ≥ Data/MC

0.5 1 1.5

1 2

  • add. jets

dN σ d σ 1

0.1 0.2 0.3 0.4 0.5 Data MadGraph+Pythia

2

= 4*Q

2 F

µ =

2 R

µ MadGraph /4

2

= Q

2 F

µ =

2 R

µ MadGraph MadGraph matching up MadGraph matching down = 7 TeV s at

  • 1

CMS, L = 5.0 fb Lepton+Jets Combined

  • add. jets

N

1 2 ≥ Data/MC

0.5 1 1.5

Systematic uncertainties evaluated with pseudoexperiments Best agreement with MadGraph+Pythia and POWHEG+Pythia, MC@NLO+Herwig shows discrepancies

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 18/42

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SLIDE 19

Additional jets

Kinematic distributions for the leading pT additional jets

Additional jets defined as the jets in visible phase space NOT selected by the kinematic reconstruction

1st leading add. jet 2nd leading add. jet

  • add-jet / 0.4
st

1 1 2 3 4 5 6 7

3

10 × = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined

Data Signal t t Other t t Single Top W+Jets µ µ ee/ → * γ Z / τ τ → * γ Z / Diboson η

  • 2
  • 1

1 2

MC N data N 0.5 1 1.5
  • add-jet / 20 GeV
st

1 1 2 3 4 5 6 7

3

10 × = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined

Data Signal t t Other t t Single Top W+Jets µ µ ee/ → * γ Z / τ τ → * γ Z / Diboson GeV

T

p 50 100 150 200 250 300 350 400

MC N data N 0.5 1 1.5
  • add-jet / 0.4
nd

2 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

3

10 × = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined

Data Signal t t Other t t Single Top W+Jets µ µ ee/ → * γ Z / τ τ → * γ Z / Diboson η

  • 2
  • 1

1 2

MC N data N 0.5 1 1.5
  • add-jet / 20 GeV
nd

2 0.5 1 1.5 2 2.5 3

3

10 × = 8 TeV s at

  • 1

CMS Preliminary, 19.6 fb Dilepton Combined

Data Signal t t Other t t Single Top W+Jets µ µ ee/ → * γ Z / τ τ → * γ Z / Diboson GeV

T

p 50 100 150 200 250 300 350 400

MC N data N 0.5 1 1.5

Good agreement between data and MC (similar to 7 TeV results)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 19/42

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SLIDE 20

Additional jets

pT of 1st and 2nd leading additional jets (8 TeV)

Comparison with various theory predictions Distributions at reconstructed level (no unfolding applied!), background is subtracted using MC predictions All predictions normalised to in situ measured cross-section (with MadGraph)

50 100 150 200 250 300 350 400

Events / binwidth

50 100 150 200 250 300 350 400 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig (GeV)

T

additional jet p

st

1 50 100 150 200 250 300 350 400 MC/data

0.6 0.8 1 1.2 1.4

50 100 150 200 250 300 350 400

Events / binwidth

50 100 150 200 250 300 350 400 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down (GeV)

T

additional jet p

st

1 50 100 150 200 250 300 350 400 MC/data

0.6 0.8 1 1.2 1.4 50 100 150 200 250 300 350 400

Events / binwidth

20 40 60 80 100 120 140 160 180 200 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig (GeV)

T

additional jet p

nd

2 50 100 150 200 250 300 350 400 MC/data

0.6 0.8 1 1.2 1.4 50 100 150 200 250 300 350 400

Events / binwidth

20 40 60 80 100 120 140 160 180 200 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down (GeV)

T

additional jet p

nd

2 50 100 150 200 250 300 350 400 MC/data

0.6 0.8 1 1.2 1.4

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 20/42

slide-21
SLIDE 21

Additional jets

η of 1st and 2nd leading additional jets (8 TeV)

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2

Events / binwidth

1000 2000 3000 4000 5000 6000 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig η additional jet

st

1

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2 MC/data

0.6 0.8 1 1.2 1.4

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2

Events / binwidth

1000 2000 3000 4000 5000 6000 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down η additional jet

st

1

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2 MC/data

0.6 0.8 1 1.2 1.4

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2

Events / binwidth

200 400 600 800 1000 1200 1400 1600 1800 2000 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig η additional jet

nd

2

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2 MC/data

0.6 0.8 1 1.2 1.4

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2

Events / binwidth

200 400 600 800 1000 1200 1400 1600 1800 2000 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down Data MadGraph+Pythia

2

4*Q /4

2

Q Matching up Matching down η additional jet

nd

2

  • 2
  • 1.5
  • 1
  • 0.5

0.5 1 1.5 2 MC/data

0.6 0.8 1 1.2 1.4

⋄ MadGraph+Pythia, Powheg+Pythia provide a reasonable description ⋄ MC@NLO+Herwig fails to describe 2nd

  • add. jet distributions

⋄ Lower scale (Q2) sample predicts lower yields than data

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 21/42

slide-22
SLIDE 22

Veto on additional jets

t¯ t production with a veto on additional jet activity

gap fraction - dilepton channel

Jet activity arising from quark and gluon radiation produced with the t¯ t system is quantified with a jet veto

f (pT) = N(pT )

Ntotal

N(pT) are the events without 1 (2) additional jets with pT above a threshold Sensitive to the (2nd) leading-pT emission.

f (HT) = N(HT )

Ntotal

N(HT) is the number of events in which the scalar sum of the pT of the additional jets is less than a certain threshold, HT = padd.jets

T

Sensitive to all hard emission accompanying t¯ t system Gap fraction in data corrected for detector effects to particle level using MadGraph: for each value of the threshold the ratio of the “true” and “reconstructed” simulated gap fraction is computed and applied to data.

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 22/42

slide-23
SLIDE 23

Veto on additional jets

Gap fraction (1st add. jet, 2nd add. jet pT)

Full pseudorapidity range

50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.9 0.95 1 1.05 1.1

40 60 80 100 120 140 160 180 200

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.9 0.95 1 1.05 1.1

40 60 80 100 120 140 160 180 200

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

⋄ MadGraph+Pythia, Powheg+Pythia provide a reasonable description for both jet-pT threshold. ⋄ Gap fraction as a function of 1st add. jet pT better described with MC@NLO+Herwig. MadGraph with decreased Q2 scale predicts lower gap fraction values than the measured ones.

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 23/42

slide-24
SLIDE 24

Veto on additional jets

Gap fraction as a function of HT

HT = padd.jets

T

50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.9 0.95 1

50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.9 0.95 1

⋄ Reasonable agreement between MadGraph+Pythia, Powheg+Pythia and data. ⋄ Gap fraction slightly better described by MadGraph with increased matching threshold.

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 24/42

slide-25
SLIDE 25

Veto on additional jets

Gap fraction: pT first additional jet

Different rapidity ranges

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.96 0.98 1 1.02

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 25/42

slide-26
SLIDE 26

Veto on additional jets

Gap fraction as a function of HT

Different rapidity ranges

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.96 0.98 1 1.02

50 100 150 200 250 300 350 400

Gap fraction

0.8 0.85 0.9 0.95 1 1.05 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.96 0.98 1 1.02

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 26/42

slide-27
SLIDE 27

Summary

Summary and Outlook

Presented t¯ t production with additional jet activity in the l+jets and in the dilepton channels. ⋄ Normalised t¯ t production cross section as a function of jet multiplicity and additional jet multiplicity ⋄ Kinematics of the additional jets ⋄ Gap fraction Compared to different MCs and parameter variations from Madgraph. In general, good agreement between data-MC observed with different predictons. Consistent result among channels and measurements. Often, experimental precision smaller than spread due to parameter

  • variation. → Variations could be reduced

Working towards comparisons with other predictions (Powheg+Herwig) and NLO+Parton Showering multileg generators like aMC@NLO.

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 27/42

slide-28
SLIDE 28

Summary

Questions

Is it actually feasible/meaningful to constrain the MC radiation parameters (Q2, matching) with measurements? Which other measurements would be useful? Additional jets: diff. xsec as a function of kin. variables, HT ratio Njets≥2/Njets≥1 as function of ptt

T , <NJet> vs ptt T ?

???

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 28/42

slide-29
SLIDE 29

Summary

BACK UP

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 29/42

slide-30
SLIDE 30

Summary

t¯ t+b¯ b: ratio of b- to light-flavour jets

CMS-PAS-TOP-13-010

Comparison with NLO QCD calculations Irreducible BG for t¯ t+H(b¯ b) Measure ratio σ(t¯ tb¯ b)/σ(t¯ tjj): large cancellation

  • f uncertainties

Selection: dilepton events with ≥4 jets with pT > 20 (40) GeV, ≥2 b–tagged jets Signal extraction by fit to the measured b-tagging algorithm discrimators Corrected to particle level Dominant systematic: mistag efficiency

R=0.023±0.003(stat.)±0.005(sys.) for 20 GeV [MadGraph (Powheg): 0.016 (0.017)] R=0.022±0.004(stat.)±0.005(sys.) for 40 GeV [MadGraph (Powheg): 0.013 (0.014)]

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 30/42

slide-31
SLIDE 31

Summary

Top quarks

MET Typical cut range 20-40 GeV, not applied for all analysis (lep+jets, dilepton) Leptons Up to two high pT leptons Isolated, high pT from W, soft leptons in b-jets With pT >20 GeV |η| <2.5 Trigger largely based on leptons (Single/double (isolated) lepton) Jets Two to six high pT jets (up to 2 b-tags, might use τ-tagging) Jets defined with anti-kT algorithm with cone ∆R=0.5 pT >20-30 GeV |η| <2.5 Trigger on l+jets signatures b-tagging Uses secondary vertices and/or IP information Efficiencies and fake rates are calibrated by using data

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 31/42

slide-32
SLIDE 32

Summary

Selection and analysis strategy

Full 2011 data (7 TeV, 5.0±0.1 fb−1) and 2012 data (8 TeV, 19.7±0.1 fb−1) ⋄ Signal: t¯ t MadGraph+Pythia (normalised to NNLO+NNLL)

For comparison: POWHEG+Pythia and MC@NLO+Herwig MadGraph+Pythia with varied hadronisation/renormalization scale (Q2) and jet-parton matching threshold.

⋄ Backgrounds:

Z/γ∗+jets: MadGraph+Pythia (dominant BG ee, µµ channels) W+jets: MadGraph+Pythia (dominant BG l+jets) Single top (s-, tW-channel): POWHEG+Pythia Diboson (WW,WZ,ZZ): Pythia QCD: Pythia (data driven for l+jets)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 32/42

slide-33
SLIDE 33

Summary

Selection and analysis strategy

Dilepton channels

Event reconstruction: Kinematic reco. underconstrained (2 ν) ⋄ mW ≡80.4 GeV, mt ≡ m¯

t fixed

⋄ pν1

T + pν2 T = E miss T

⋄ vary mT between 100-300 GeV (1 GeV steps) ⋄ prefer solutions with b-tagged jets ⋄ choose solution with best reco. neutrino energy w.r.t MC spectrum Background estimation: ⋄ Z/γ∗+jets estimated from data: The normalisation is determined using the events inside the Z-peak region, after substracting the contamination from non-Z/γ∗+jets, derived with eµ events. ⋄ Other BGs (single top, dibosons, etc) estimated from MC Scale Factors: PU, Lepton selection, trigger SF, b-tag SF and kinematic reconstruction

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 33/42

slide-34
SLIDE 34

Summary

Selection and analysis strategy

lepton+jets channels

Background estimation ⋄ W+jets estimated from data:

Normalization is from data using charge asymmetry property of W+jets events. Jet multiplicity shape is from MC Additional correction of heavy flavour fraction

⋄ QCD: data driven

Define sideband (1 b-tag) and signal (≥2 b-tag) regions with events with inverted lepton isolation Fit MET from sideband to obtain the QCD normalization parameter Multiply the QCD shape in the signal region by the QCD normalization parameter

⋄ Single top, Z/γ∗+jets and diboson are from MC Scale Factors: PU, Lepton selection, trigger SF, b-tag SF

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 34/42

slide-35
SLIDE 35

Summary

Phase space definitions

Measurements are presented at particle level in the visible phase space. Additionally GenJets must fullfill: ∆R(genJet,selected leptons)>0.4

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 35/42

slide-36
SLIDE 36

Summary

Control Plots: Jet pT

Dilepton: pT >30 GeV, l+jets: pT >35 GeV

Dilepton l+jets

Jets / 10 GeV 1 2 3 4 5 6 7 8

3

10 ×

Data Signal t t Other t t Single t W+Jets µ µ ee/ → * γ Z / τ τ → * γ Z / Diboson QCD Multijet

Dilepton Combined = 7 TeV s at

  • 1

CMS, L = 5.0 fb

GeV

T

p

50 100 150 200 250

Data/MC 0.5 1 1.5

50 100 150 200 250

Jets / 10 GeV 5 10 15 20 25

3

10 ×

Data Signal t t Other t t Single t W+Jets *+Jets γ Z/ Diboson QCD Multijet

Lepton+Jets Combined = 7 TeV s at

  • 1

CMS, L = 5.0 fb

[GeV]

T

p

50 100 150 200 250

Data/MC 0.5 1 1.5

Good description of data within uncertainties.

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 36/42

slide-37
SLIDE 37

Summary

Results: dilepton channel

Jet pT > 60 GeV

1 2 3 4 5 6

jets

dN σ d σ 1

  • 5

10

  • 4

10

  • 3

10

  • 2

10

  • 1

10 1 Data MadGraph+Pythia MC@NLO+Herwig POWHEG+Pythia = 7 TeV s at

  • 1

CMS, L = 5.0 fb Dilepton Combined

jets

N

1 2 3 4 5 6 ≥ Data/MC

0.5 1 1.5

1 2 3 4 5 6

jets

dN σ d σ 1

  • 5

10

  • 4

10

  • 3

10

  • 2

10

  • 1

10 1 Data MadGraph+Pythia

2

= 4*Q

2 F

µ =

2 R

µ MadGraph /4

2

= Q

2 F

µ =

2 R

µ MadGraph MadGraph matching up MadGraph matching down = 7 TeV s at

  • 1

CMS, L = 5.0 fb Dilepton Combined

jets

N

1 2 3 4 5 6 ≥ Data/MC

0.5 1 1.5

⋄ MadGraph+Pythia, POWHEG+PYTHIA provide a reasonable description ⋄ MC@NLO+HERWIG doesn’t generate large jet multiplicities. ⋄ Choice of lower scale gives slightly worse description of the data.

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 37/42

slide-38
SLIDE 38

Summary

Gap fraction: results 7 TeV

Gap fraction in data corrected for detector effects to particle level using MadGraph pT HT

50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =7 TeV s at

  • 1

CMS, 5.0 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.9 0.95 1 50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =7 TeV s at

  • 1

CMS, 5.0 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.9 0.95 1

Gap fraction better described by MC@NLO+HERWIG Dominant systematic uncertainties: JES uncertainty, BG contamination

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 38/42

slide-39
SLIDE 39

Summary

Gap fraction: results 7 TeV

pT HT

50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =7 TeV s at

  • 1

CMS, 5.0 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

st

1 50 100 150 200 250 300 350 400 Theory/Data

0.9 0.95 1 50 100 150 200 250 300 350 400

Gap fraction

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 =7 TeV s at

  • 1

CMS, 5.0 fb

Dilepton Combined

Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

H

50 100 150 200 250 300 350 400

Theory/Data

0.9 0.95 1

Decreasing the Q2 scale, jet-parton matching threshold worsens the agreement with data

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 39/42

slide-40
SLIDE 40

Summary

pT second additional jet

Gap fraction for different pseudorapidity ranges.

40 60 80 100 120 140 160 180 200

Gap fraction

0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<0.8 η | Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

40 60 80 100 120 140 160 180 200

Gap fraction

0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

40 60 80 100 120 140 160 180 200

Gap fraction

0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia POWHEG+Pythia MC@NLO+Herwig [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

40 60 80 100 120 140 160 180 200

Gap fraction

0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<0.8 η | Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

40 60 80 100 120 140 160 180 200

Gap fraction

0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<1.5 η 0.8<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

40 60 80 100 120 140 160 180 200

Gap fraction

0.9 0.92 0.94 0.96 0.98 1 1.02 1.04 =8 TeV s at

  • 1

CMS Preliminary, 19.6 fb

Dilepton Combined

|<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down |<2.1 η 1.5<| Data Syst+Stat error MadGraph+Pythia

2

MadGraph 4*Q /4

2

MadGraph Q MadGraph matching up MadGraph matching down [GeV]

T

additional jet p

nd

2 40 60 80 100 120 140 160 180 200 Theory/Data

0.96 0.98 1 1.02

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 40/42

slide-41
SLIDE 41

Summary

Matching scale (MadGraph only)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 41/42

slide-42
SLIDE 42

Summary

Matching scale (MadGraph only)

  • C. Diez Pardos (DESY)

Durham, 18 July 2014 42/42