1

Measurement of the Top Quark

Pair Production Cross Section

with the ATLAS Detector

Andrea Bangert

University of California at Santa Cruz

October 29th, 2008

2

Overview

• Large Hadron Collider• ATLAS Experiment• Standard Model Top Quark

• Pair production mediated by strong interaction • Top decay mediated by weak interaction

• Theoretical cross section• Cross Section Measurement

• Luminosity • Event Selection and efficiencies• Reconstructing top• Backgrounds

• Summary

3

Large Hadron Collider

4

Large Hadron Collider

Large Hadron Collider

• 27 km circumference, 150 m depth

• Proton-proton collisions, ECM = 14 TeV

• Design luminosity L = 1034 cm-2 s-1

• Experiments: ATLAS, ALICE, CMS, LHCb

5

Components of a Collider Experiment

6

The ATLAS Experiment

• Lead / liquid argon electromagnetic calorimeter

• Electron, photon identification

• Hadronic calorimeter• Scintillator-tile barrel

calorimeter • Copper / liquid argon

hadronic end-cap calorimeter

• Tungsten / liquid argon forward calorimeter

• Air-core toroid magnet• Instrumented with muon

chambers• Muon spectrometer

• Muon momentum

• Inner Detector, superconducting solenoid magnet..

• Pixel detector, semiconductor tracker, transition radiation tracker• Momentum and vertex measurements, electron, tau and heavy flavor identification

7

ATLAS Goals

• Electroweak symmetry breaking

• Higgs boson

• Supersymmetry

• Gauge bosons

• Compositeness

• mt and mW

• QCD

mH = 129 +74-29 GeV

mW = 80.399 ± 0.025 GeV

mt = 172.4 ± 1.2 GeV

mH > 114 GeV (95% CL)

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• Discovered at Tevatron in 1995• Completed 3rd generation of fermions

• Extremely massive:• mt = 172.4 ± 1.2 GeV• mt ≈ 185 amu • mAg < mt < mAu

• Top-antitop pairs produced via strong interaction

• Top decays via weak interaction, t → W b

Standard Model Top Quark

9

Top Quark Pair Production

• Mediated by strong interaction

• Rate is proportional to cross section tt and luminosity L

• L = 1034 cm-2 s-1

L ≈ 36 pb-1 / hour• Theoretical cross section is

σtt = 919 +76-55 pb

• 9 top–antitop pairs / second• 2.7 million pairs / week• 76 million pairs / year

10

Parton Distributions

• Partonic cross sections

• Short-distance hard scattering

• Calculated to NLO in perturbative QCD

• Parton distribution functions

• Non-perturbative, universal

• Determined from data

• CTEQ6.6M

Parton Distribution Functions

g, u, d, ubar

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Factorization Theorem• ij are partonic

cross sections• f(x) are parton

distributions• i, j are incoming

partons

• N. Kidonakis and R. Vogt, 2008

• ECM = 14 TeV• CTEQ6.6M PDFs

• mt = 172 GeV• tt = 919 +76

-55 pb

Measurement of σtt serves as experimental test of pQCD

tt(mt) at the LHC

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Top Decay

• W decay: • W → l v Γ ≈ 1/3 • W → j j Γ ≈ 2/3

• Top-antitop decays:• “dileptonic”• “semileptonic”• “hadronic”

• Cross section can be measured in dileptonic, semileptonic and hadronic decay channels.

tt → W+b W-b → (l+ vl b) (l- vl b)tt → Wb Wb → (l vl b) (j j b) tt → Wb Wb → (j j b) (j j b)

Γ ≈ 1/9Γ ≈ 4/9Γ ≈ 4/9

• Top decay: • Γ(t→W+b) = |Vtb|2 = 0.998• t ~ 5 10-25 s• No top hadrons

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Why measure the cross section?

• Test perturbative QCD

• Top production is a “standard candle”

• Measurements involving known top properties will allow us to calibrate the ATLAS detector

• Top pair production will be a significant background for other measurements

• Physics not predicted by the Standard Model could increase the cross section significantly

• Could affect the branching ratios for the various top decay channels (t → H+b)

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Cross Section Measurement

• Estimate background rates• QCD multijets • Electroweak W+N jet production• Single top production

• Estimate εtt

• Use Monte Carlo samples• Include trigger efficiencies from data

• Luminosity • Relative luminosity measured by LUCID• Absolute calibration from LHC machine parameters

• Uncertainty of 20% to 30% expected initially

15

Luminosity

Necessary input for cross section measurement.

f = 11 kHz

F = 0.9

Np = 1011 protons / bunch

Nb = 2808 bunches / beam

σ* = 16 m

Initial uncertainty is 20% to 30%

Limit on precision is L ~ 10%

Calculate L using beam parameters.

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Trigger • tt lb jjb allows use of single lepton trigger

• Electron trigger e25i• Isolated electron

• pT > 18 GeV

• For pT > 25 GeV, trigger= 99%• tt → evb jjb

• After event selection• pTe > 10 GeV

• εtrigger = 84%

• Muon trigger mu20• Muon with pT > 17.5 GeV• tt → μvb jjb

• After event selection• pTm > 10 GeV

• εtrigger = 78%

• Efficiencies must be estimated from dataTrigger Efficiency in tt→lvb jjb

Level 1 Trigger

Event Filter

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Backgrounds• W + jets• QCD multijets• top pair production with

dileptonic, hadronic decay• single top production• diboson production• Drell-Yan Z → ll

tt → lvb jjb signal

W + 4 jets

diboson production (WW)

single top production

σ ≈ 100 pb

σ ≈ 250 pb

σ ≈ 24 pb

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Event Selection

• Selection Cuts• Exactly one e or μ

• Isolated • E∆R=0.20 < 6 GeV • Energetic

• pT > 20 GeV• Central, |η| < 2.5

• At least four jets• Energetic• pTj > 40 GeV• pT j4 > 20 GeV• Central, || < 2.5• No b-tagging

• MET > 20 GeV

• Before cuts S/B = 0.16• After cuts S/B = 1.56

Number of events, L = 100 pb-1

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Invariant Masses• tt → Wb Wb → lvb jjb

• Reconstruct t → Wb → jjb• Each event contains N jets• Create all possible trijet

combinations• Choose combination with

highest pT to represent t → jjb

• Reconstruct W → jj• t → jjb contains three jets• Three dijet combinations are

possible• Choose dijet combination with

highest pT to represent W → jj

• Possible to cut on mjjb, mjj

L = 100 pb-1, tt → evb jjb

t jjb

W jj

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Transverse Masses

W l

t Wb lb

L = 973 pb-1

W+jets, tt lb jjb

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Small selection efficiencies: dileptonic ttbar hadronic ttbar single top W→τv

Large selection efficiencies: W→ev plus 5

partons W→μv plus 4

partonsA first estimate of δε due to Jet Energy Scale was performed by varying cuts on jet pT by 5%.

For ttlb jjb, / ~ 8% which implies / ~ 8%.

Selection Efficiencies

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W + N Jets Background

is large σ is large N is large• Significant source of

uncertainty for tt

Systematic Uncertainty on σ(W+)+Njets

CERN-PH-TH/2007-066

• Most dangerous background.

23

W + N Jets

Low and high estimates of W+N jets contribution in 100 pb-1

tt / tt 8%

Alpgen: • W+2j = 2032 pb

• W+3j = 771 pb

• W+4j = 273 pb

• W+5j = 91 pb

Assign uncertainties: • W+2j = 20%• W+3j = 30%• W+4j = 40%• W+5j = 50%

Events in 100 pb-1:• NW+2j = 53 ± 10 • NW+3j = 271 ± 81• NW+4j = 775 ± 310• NW+5j = 800 ± 400

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QCD Multijet Background

• Reducible background • MET is due to

• b→Wc→lνc• Mismeasurement

• Leptons are • Non-prompt• b→Wc→lνc• “Fake”• Not isolated

• Fake Rate • R~10-5 (ATLAS TDR)• R = R(pT, η)

• Difficult to model QCD multijet background adequately using Monte Carlo samples, detector simulation

• Contribution will be measured from data

Hard cuts placed on jets. No cuts on leptons.

MET

Electron Isolation

Distributions normalized to contain 10,000

events.

10,000 events

∆R = 0.2

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Consistency Check• Sample contains ttlbjjb, ttlblb

• ~10% of sample used as “data”

• ~90% of sample used as model

• Ldata = 97 pb-1, Ndata ~ 45,000

• LMC = 970 pb-1, NMC ~ 450,000

• Efficiencies calculated using model

• Assume εdata = εMC

• Number of background events in “data” predicted by model

σ·Γ = 246.0 ± 3.5 (stat) pbFrom Monte Carlo: σ·Γ = 248.5 pb

tjjb

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Next Steps• Implement analysis in

Athena 14.2.23• Run over signal Monte Carlo• Perform “consistency check”• W+Jets Monte Carlo• Implement trigger decision• Optimize selection cuts

• Consider a cut on invariant or transverse masses

• Compare different methods of reconstructing tjjb and Wjj

• Jet Energy Scale

• Prepare analysis for data

10,000 events

tt lb jjb, W l, QCD

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Conclusion• Measurement of tt

• Test of perturbative QCD• Use to calibrate detector performance • Prerequisite to observation of new signatures

• Observation of tt lb jjb will utilize all components of the detector

• Counting experiment using L=100 pb-1 • W+N jets will be most significant background• QCD multijet contribution determined from data

• Uncertainty tt determined by L ~ 20% - 30%

• Looking ahead to data

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Backup Slides

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References• “The Large Hadron Collider”, Lyndon Evans, New Journal of Physics 9 (2007)

• “LHC Machine”, L. Evans, P. Bryant, JINST (2008)

• “Collider Physics”, Dieter Zeppenfeld (1998), hep-ph/9902307

• “The ATLAS Experiment at the CERN LHC”, JINST (2008)

• ATLAS Technical Design Report (1999)

• “ATLAS Forward Detectors for Measurement of Elastic Scattering and Luminosity”, ATLAS TDR 18 (2008)

• “The theoretical top quark cross section at the Tevatron and the LHC”, N. Kidonakis and R. Vogt (2008), hep-ph/08053844

• “Top Quark Physics at the LHC”, W. Bernreuther (2008), hep-ph/08051333

• “The Top Priority at the LHC”, Tao Han (2008), hep-ph/08043178

• “Top Studies for the ATLAS Detector Commissioning”, S. Bentvelsen, M. Cobal, ATL-PHYS-PUB-2005-024 (2005)

• Particle Data Group, http://pdg.lbl.gov/

• “Precision Electroweak Measurements on the Z Resonance”, LEP and SLD (2006), hep-ex/0509008

• “Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions”, CERN-PH-TH/2007-066

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Units

• 1 amu = 0.931 GeV

• 1 barn = 10-28 m2

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Theory

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Electroweak Precision Measurements

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EM, GF, mZ → sin2θW 1 - (mW / mZ)2

mW2 ~ 1 / GF sin2 θW (1-▲r)

▲r contains all one-loop corrections to mW.

(▲r)top ~ GFmt2 / tan2 θW

(▲r)Higgs ~ GF mW2 ln (mH

2 / mZ2)

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CKM Matrix

Vtb ≈ 0.999100 Γ(t→Wb) = |Vtb|2 = 0.998

The charged current W± couples to quarks q and q’ with coupling given by CKM matrix element Vqq’.

Branching ratios for decays which do not mix generations are thus close to unity.

The diagonal elements are close to unity, = |Vus| = 0.2212 ± 0.0025

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Branching Ratios

(W e) = (10.80 ± 0.09)% (W ) = (10.75 ± 0.13)% (W ) = (10.57 ± 0.15)% (W jj) = (67.60 ± 0.27)%

(tt → Wb Wb → lvb lvb) = 10.3%(tt → Wb Wb → lvb jjb) = 43.5% (tt → Wb Wb → jjb jjb) = 46.2%

[Particle Data Group, C. Amsler et al; T. Liss and A. Quadt, 2008]

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Single Top Production

• t channel exchange of W boson

• s channel exchange of W boson

• associated production of real W and top

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Luminosity and Machine

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LHC Machine

Parameters

• Circumference: 26.7 km• Operating temperature: 1.9 K• Dipole field at 7 TeV: 8.33 Tesla• Stored energy in magnets: 600 MJ• Proton energy during injection: 0.45 TeV• Proton energy during collisions: 7 TeV• Protons per bunch: 1.15 1011

• Number of bunches: 2808• Bunch crossing rate: 40 MHz• Orbit frequency: 11.245 kHz• Beam current: 0.58 A• Nominal bunch spacing: 24.95 ns• Design luminosity: 1034 cm-2s-1

• Kinetic energy per beam: 362 MJ• Power radiated per beam: 3.8 kW• Inelastic events per crossing: 23• Nominal bunch width at interaction point: 16 m• Total bunch length: 1.0 ns• Normalized transverse emittance: 3.75 m• Total longitudinal emittance: 2.5 eV s at interaction point: 0.5m• Crossing angle at interaction point: 320 rad

38

ATLAS Forward Detectors

• LUCID• “Luminosity measurement Using Cherenkov Integrating Detector”• Array of Cherenkov tubes located 17 m from interaction point• Detects inelastic p-p scattering in forward region • Measures integrated luminosity• Provides online monitoring of instantaneous luminosity • Initial calibration based on machine parameters, L ~ 20% - 30%• Later calibration provided by ALFA, L ~ 5%

• ALFA• “Absolute Luminosity for ATLAS”• Scintillating fibre trackers inside Roman pots • Located 240 meters from interaction point • Measures elastic Coulomb scattering at small angles• Measurements performed under special beam conditions• Final installation and first measurements in 2009

39

Measuring Luminosity• Methods of measuring luminosity:

• Measure rate of process with large, well-known cross section .

• R = dN / dt = L σ• More applicable to e+e- colliders than to hadron colliders. • Example: QED Babha scattering.

• Calculate luminosity using beam parameters. • Typical precision is 5% - 10%.

• Use the optical theorem (ALFA, 2009).• Measure total rate of pp interactions Rtotal. • Measure rate of forward elastic scattering dRelastic/dt |t=0.

• Protons scatter with very small momentum transfer t.• L dRelastic / dt |t=0 = Rtotal

2 (1 + ρ2) / 16 π• ρ is ratio of real to imaginary part of elastic forward

amplitude. • Typical precision is 5% - 10%

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Uncertainty on Luminosity

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Reconstruction

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Selection Cuts• Inclusive kT algorithm, E scheme, D=0.4. • Hard Jet Cuts

• No cuts are applied to lepton quantities• Require at least four jets:

• |η| < 5.0 • Lead jet must have pT(j1)>80 GeV• Three subsequent jets must have pT(j)>40

GeV• Selection Cuts

• Exactly one isolated, high-pT e or • E∆R=0.20 < 6 GeV • pT(l) > 20 GeV, |η| < 2.5

• Muons are reconstructed by Staco • Electron candidates must:

• Be reconstructed by eGamma• Fulfill (isEM==0)• Exclude crack region in liquid argon

calorimeter, 1.37<|η|<1.52 • At least four jets

• |η| < 2.5• First three jets have pT(j) > 40 GeV• Fourth jet has pT(j4) > 20 GeV• Jets are removed if ∆R(j,e)<0.4

• MET > 20 GeV.

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Jet pT

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Missing Transverse Energy

• Neutrinos do not interact with the detector.• Initial pT of colliding proton-proton system is zero. • Conservation of momentum requires net pT of all decay

products to be zero.• Assumption: ET and pT of any object except are measured

perfectly.• Then Σi ET + ET = 0 where sum is over all visible particles. • Conclusion: “Missing Transverse Energy” (MET) is ETn

• ET = MET = -Σi ET

• Events which produced an energetic have significant MET.• Events which did not produce a have little MET.

• Caveat: If two were present, information is lost. • Caveat: no measurement is perfect. Instrumental effects can

result in energy imbalance and can ‘fake’ the signature. • Use known mass of W boson and W → l data to calibrate and

test performance of MET reconstruction.

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• Flag designed to identify electrons and reject jets • Represents combinations of cuts imposed on reconstructed

quantities• Electromagnetic and hadronic calorimeters:

• Very little hadronic leakage (1st bit).• Energy deposit in electromagnetic calorimeter is narrow in width

(2nd bit).• Energy deposit in electromagnetic calorimeter has one narrow

maximum, no substructure (3rd bit).• Inner detector:

• At least nine precision hits from pixel detector and semiconductor tracker; small transverse impact parameter.

• η and φ of track are extrapolated to calorimeter cluster; extrapolated and measured values are required to match.

• Energy measured in electromagnetic calorimeter is required to match momentum measured in inner detector.

• isEM == 0 demands that each electron candidate pass all cuts.

isEM: Quality Control for Electrons

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Fake Leptons

• Electrons• QCD multijet event is

background if jet fakes electron

• Require isolated electrons• ET (∆R < 0.2) < 6 GeV

• Muons• QCD multijet event is

background if b-jet produces μ

• Distinguish between:• Hard process:

t → Wb → μvb • b decay:

b → Wc → μvc • Require separation between

μ and jet• ∆R(μ, j) > 0.2

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Invariant Mass

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Transverse Mass

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HT

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mT(W) and HT at CDF

• QCD multijets tend to have very low mTW

• Cut at mTW > 20 GeV helps to eliminate QCD

• Top-antitop decays tend to have large HT

• Cut at HT > 200 GeV helps to select top pairs

CDF: hep-ex/0607035

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b-tagging• Purpose

• Identification of heavy flavor jets (b)• Suppression of light flavor jets (u, d, s)

• Importance• Top quark events produce b quarks

• Most W + jets, QCD multijet events

produce only light quark jets• Use b-tagging to suppress

significant sources of background • Caveat

• Requires precise alignment of inner detector

• Several months of data-taking necessary

• Interplay between tt sample, b-tagging:• In a pure sample of tt events, every

event contains two b jets • Use to test b-tagging performance

Nb-jets > 1

Top-antitop

Single top

W + jets

tt → evb jjb

L = 100 pb-1

W > 7.05

t → jjb

Top-antitop

Single top

W + jets

52

Trigger• L1 trigger

• 4x4 matrix of calorimeter towers• 2x2 central core is

“Region of Interest”• 12 surrounding towers

measure isolation

• L1_em25i requires• ET>18 GeV in ROI in EM calorimeter • ET<2 GeV in ROI in hadron calorimeter• Isolation:

• ET<3 GeV in EM calorimeter• ET<2 GeV in hadron calorimeter

• Event Filter requires ET>18 GeV• εtrigger = 99% for electrons with pT>25 GeV.• L1_mu20 requires ET>17.5 GeV.

Sample 5200, tt→evbjjb events

Event selection with pT(e) > 10 GeV

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Trigger

Trigger Efficiency in tt→evb jjb events

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Backgrounds

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Uncertainty on σW+Njets

Systematic Variation at Tevatron Systematic Variation at LHC

Proton-antiproton collisions, 1.96 TeV, W±,

Cone7 jets, ET(j)>10 GeV, |η|<2Proton-proton collisions, 14 TeV, only W+,

Cone4 jets, ET(j)>20 GeV, |η|<4.5

• “Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions”

• CERN-PH-TH/2007-066

56

Matrix Method

• Method of estimating W→lv, QCD multijet contributions

• Combines use of data, Monte Carlo• Calculate efficiencies; obtain final

numbers of events• Use Monte Carlo to obtain εW

• lW is the number of events in the Monte Carlo sample which pass loose cuts

• lW’ is number of events which also pass tight cuts

• εW = lW’ / lW

• Use data to obtain εQCD• MET < 10 GeV• lQCD is number of events in QCD sample

which pass loose cuts

• lQCD’ is number of events in QCD sample which pass tight cuts

• εQCD = lQCD’ / lQCD

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Matrix Method

• S contains N events which passed loose lepton cuts• N = NQCD + NW

• S’ contains N’ events which passed tight lepton cuts• N’ = NQCD’ + NW’ • N’= εQCD NQCD + εW NW

• The number of W→lv events in S’ is• NW’ = εW NW

• NW’= εW (εQCD N – N’) / (εQCD – εW)

• The number of QCD multijets in S’ is:• NQCD’ = εQCD NQCD

• NQCD’ = εQCD (N’ – εW N) / (εQCD – εW)

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Samples

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Samples Semileptonic and dileptonic ttbar events:

MC@NLO and Herwig. Sample 5200, TID 8037. Filter requires prompt lepton, σ*f = 461 pb.

Hadronic ttbar events: MC@NLO and Herwig. Sample 5204, TID 6015. Filter forbids prompt lepton, σ*f = 369 pb.

Single top samples: AcerMC and Pythia. Wt Production: sample 5500, TID 6958.

σ*f = 25.5 pb, W→lv plus W→jj s channel: sample 5501, TID 6959.

σ*f = 2.3 pb, filter requires W→lv. t channel: sample 5502, TID 6960.

σ*f = 81.5 pb, filter requires W→lv.

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Samples W+Njets events

Alpgen and Herwig. Samples 8240-8250 Filter requires 3 jets

pT>30 GeV, |eta|<5. QCD multijet events

Alpgen and Herwig. Samples 5061, 5062, 5063, 5064. σ*f=21188 pb, σ*f=53283 pb, σ*f=9904 pb, σ*f=6436

pb. Generated in 11.0.42, reconstructed in 12.0.6. Filter requires 4 jets with |η|<6.

Lead jet must have pT(j1)>80 GeV. 3 subsequent jets must have pT>40 GeV.

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Samples for Consistency Check

• Semileptonic and dileptonic ttbar events • csc11 #5200, σ = 461 pb, mt = 175 GeV.• Used ~10% of sample as “data”. • Used remaining ~90% of sample as “Monte Carlo”. • Ldata = 97 pb-1, Ndata ~ 45,000 • LMC = 973 pb-1, NMC ~ 450,000.

• Reconstructed with Athena 11.0.42.

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Top Samples

Process sampleCross

section [pb]

Theoretical uncertainty on

σ [pb]

εfilter σ*f [pb] L [pb-1] Weight

(100 pb-1)

Initial events

Final

events

Efficiency [%]

stat. uncertainty

Wtd final

events

ttbar

tt→(evb)(jjb)

5200 833 100 0.54 461 770.7 0.130

94304 17932 19.02 0.13 2327

tt→(μvb)(jjb) 94489 27975 29.61 0.15 3630

tt→(τvb)(jjb) 95292 4049 4.25 0.07 525

tt→(lvb)(lvb) 70324 6072 8.63 0.11 788

tt→(jjb)(jjb) 5204 833 100 0.46 369 190.6 0.525 65742 237 0.36 0.02 133

Single top

Wt production 5500 25.5 421.6 0.237 10750 744 6.92 0.24 176

s channel 5501 2.3 5652 0.018 13000 159 1.22 0.10 3

t channel 4402 81.5 152 0.657 12400 437 3.52 0.17 287

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Process Cross section [pb]

Relative uncertainty on σ

MLM match rate

εfilter σ*f [pb]

L [pb-1] Weight

(100 pb-1)

Initial events

Final

events

Efficiency [%]

stat. uncertainty

Wtd

final events

W→ev

2 partons 2032 0.20 0.402 0.262 214 593.0 0.1686 126916 102 0.08037 0.00008 17

3 partons 771 0.30 0.301 0.534 124 556.8 0.1796 69006 479 0.694 0.032 86

4 partons 273 0.40 0.252 0.78 53.7 232.3 0.4306 12463 680 5.456 0.203 293

5 partons 91 0.50 0.264 0.929 22.3 165.8 0.6032 3700 423 11.432 0.523 255

W→μv

2 partons 2032 0.20 0.402 0.020 16.3 260.1 0.3844 4250 82 1.929 0.211 32

3 partons 771 0.30 0.304 0.276 64.7 185.5 0.5391 12000 304 0.253 0.143 164

4 partons 273 0.40 0.229 0.576 36.0 446.4 0.2240 16073 1859 11.566 0.252 416

5 partons 91 0.50 0.264 0.84 20.2 173.4 0.5766 3500 837 23.914 0.721 483

W→τv

2 partons 2032 0.20 0.415 0.104 87.7 233.2 0.4289 20450 9 0.044 0.015 4

3 partons 771 0.30 0.303 0.373 87.1 149.2 0.6703 13000 32 0.246 0.043 21

4 partons 273 0.40 0.245 0.686 45.9 119.9 0.8342 5500 79 1.436 0.160 66

5 partons 91 0.50 0.264 0.866 20.8 525.4 0.1903 10930 328 3.001 0.163 62

W + N Jets

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Estimated Uncertainty on W+Jets

Process Alpgen cross section [pb]

Relative uncertainty

assigned to σ

Nexp,

low

estimate

Nexp,

central

value

Nexp,

high

estimate

W+2 partons 2032 20% 42 53 63

W+3 partons 771 30% 190 271 352

W+4 partons 273 40% 465 775 1085

W+5 partons 91 50% 400 800 1200

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Selection EfficienciesProcess

Efficiency

pT(j) > 42 GeV

pT(j4) > 21 GeV

Efficiency

pT(j) > 40 GeV

pT(j4) > 20 GeV

Efficiency

pT(j) > 38 GeV

pT(j4) > 19 GeV

Uncertainty

due to ∆pT

Relative uncertainty

due to ∆pT

ttbar

tt→(evb)(jjb) 0.175 0.190 0.206 0.015 0.081

tt→(μvb)(jjb) 0.272 0.296 0.321 0.025 0.084

tt→(τvb)(jjb) 0.0388 0.0425 0.0461 0.0036 0.085

tt→(lvb)(lvb) 0.0772 0.0863 0.0950 0.009 0.103

tt→(jjb)(jjb) 0.0034 0.0036 0.0038 0.0002 0.061

Single top

Wt production 0.0603 0.0692 0.0799 0.01 0.14

s channel 0.0101 0.0122 0.0142 0.002 0.17

t channel 0.0321 0.0352 0.0396 0.004 0.11

W→ev

2 partons 0.00059 0.00080 0.00105 0.0002 0.28

3 partons 0.000549 0.00694 0.00903 0.002 0.25

4 partons 0.0468 0.0546 0.0627 0.008 0.14

5 partons 0.104 0.114 0.125 0.01 0.09

W→μv

2 partons 0.0136 0.0193 0.0264 0.007 0.33

3 partons 0.0208 0.0253 0.0323 0.007 0.23

4 partons 0.0996 0.1157 0.1318 0.016 0.14

5 partons 0.219 0.239 0.258 0.019 0.08

W→τv

2 partons 0.00034 0.00044 0.00049 0.0001 0.17

3 partons 0.0022 0.0025 0.0033 0.0008 0.22

4 partons 0.0124 0.0143 0.0173 0.003 0.17

5 partons 0.0275 0.0300 0.0325 0.002 0.08

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Efficiencies (L = 973 pb-1)