search for excited randall-sundrum gravitons from warped extra dimensions with semi-leptonic diboson...

Search for Excited Randall-Sundrum Gravitons fromWarped Extra Dimensions with Semi-Leptonic

Diboson Final States using the ATLAS detector atthe LHC

Eric Williams

Columbia University

July 2nd, 2012

Thesis Defense

Talk Overview

The Large Hadron Collider

The ATLAS detector

Why extra dimensions?

The analysis

Sources of systematic uncertainties

Final results and conclusions

E. Williams (Columbia U.) G∗ → WW → `νjj thesis defense July 2nd, 2012 2 / 41

The Large Hadron Collider

The Large Hadron Collider (LHC)

27 km circumference, 100 meters underground

Collides counter-rotating proton beams at center-of-massenergy = 7 TeV (now at 8 TeV!)

Delivered over 5 fb−1 of 7 TeV data to ATLAS in 2011

Beams collide at the centers of four experiments (detectors):

ATLAS, ALICE, CMS and LHC-bE. Williams (Columbia U.) G∗ → WW → `νjj thesis defense July 2nd, 2012 4 / 41

The ATLAS Detector

The ATLAS Detector

The ATLAS (A Toroidal LHC ApparatuS) detector is designed to be a ‘general-purpose’detector undertaking a broad range of physics analyses.


The ATLAS Detector

ATLAS is composed of components, each optimized for particular functions

Inner Detector: measures the momentum andtrajectories charged particles

Electromagnetic Calorimeters: measures theenergies of electrons, photons, and others

Hadronic Calorimeters: measures the energiesof the hadronic particles (‘jets’, protons,neutrons)

Muon System: measures the momenta ofmuons in the event

The combination of these systems allow formeasurments of ‘missing transverse energy’;the signature of particles not detected, such asneutrinos

The goal of particle detection is to reconstruct the kinematics of each collision(particle energies, directions, charges and masses), to determine whethersomething “interesting” happened during that event


Why extra dimensions?Original Randall-Sundrum (RS1) model

Modern ‘Bulk’ Randall-Sundrum (Bulk RS) model

Why extra dimensions? RS1 Model

Original Randall-Sundrum (RS1) model offers a solution to thehierarchy problem by postulating a 5th space-time bounded by two(3 + 1)-dimensional branes.

Gravity is localized aty = 0, called the UV-

or Planck-brane.

Only gravity canpropagate through

‘bulk’.

SM particles reststrictedto y = πR (IR- or TeV-brane).

Physical masses rescaledby e−πkR: gravity is weak.

The resulting metric is nonfactorizable and depends on the radius yand curvature k−1 of the extra dimension:

ds2 = e−2kyηµνdxµdxν + dy2; 0 ≤ y ≤ πR

Therefore the RS warped geometry model proposes a solution to the‘hierarchy problem’ with reasonable values of kR ∼ 11Massive excited graviton modes (G∗) are a defining feature


Why extra dimensions? Bulk RS Model

Modern RS models (bulk RS) allow SM particles into 5-D bulk

Overlap of 5-D profiles at TeV brane (and the Higgs) determineparticles masses

Suppressed coupling to bosons and lightfermions; negligible rates to γγ and ``

Enhanced coupling to heavy particles(tt,ZZ and WW )← motivates search in WWchannel!

G*! WW G*! ZZ G*! HH G*! gg G*! tT


Analysis Outline

Analysis Strategy

Data/MC Samples

Object and Event Selection

QCD Multijet Estimation

Event Preselection

Signal (W+jets) Control Region

Signal Region

(*The Ω symbol in corner of following slides denotes my contributions)

Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

→ This analysis (`νjj) part of a larger diboson resonance effort at ATLASwhich includes other decay channels: ````, ``jj, `ν`` and `ν`ν.

Analysis Strategy and Previous Limits

Diboson resonances (M > 500 GeV) are characterized by:

a high-pT W boson, decaying leptonically → `ν, (` = e, µ)

Select events with one high pT isolated leptonRequire large missing transverse energy (EmissT )

a high-pT W or Z boson, decaying hadronically → jj

Require at least two high pT jets

a peak in the four-body invariant mass M(`νjj)

Look for excess in the invariant mass of the systemSet 95% confidence limits on a narrow M(`νjj) excess

Previous RS1 G∗ → V V mass exclusion limits

Experiment L [fb−1] ProcessMass

Exclusion

CMS 4.9 G∗RS1 → ZZ 1000 GeVATLAS 1.02 G∗RS1 → ZZ 845 GeV

D0 5.4 G∗RS1 →WW 754 GeV

*Currently no published limits on bulk RS graviton production!


Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

Data/MC samples

Data samples:

L = 4.701± 0.183 fb−1

Events checked for good detector status (Good Runs List)

Monte-Carlo samples:

Weights applied to MC events to account for pile-up, as well as trigger andreconstruction efficiencies.

Background cross sections normalized to (N)NLO with scale factors (k-factors)

Full detector simulation, reconstructed with same software as data

Backgrounds Generator

W+jets Alpgen+Herwig/JimmyZ+jets Alpgen+Herwig/JimmyTop (tt and st) MC@NLO+Herwig/JimmyWW/WZ/ZZ Herwig+Jimmy

Signals (M = 500 -1500) Generator

G∗RS1 → `νjj PythiaG∗Bulk → `νjj CalcHEP+Atlfast II


https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/ExtendedPileupReweighting

Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

Object Selection: Electrons and Muons Ω

Electrons are selected based on shower shape requirements andcluster/track matching (tight++)

Muons are selected based on track quality and the combination oftracks from the muon system and inner detector (combined)

Both electrons and muons have requirements on:

longitudinal and transverse impact parameterstransverse energy isolationtransverse momentum

eνjj µνjj

Electron Pt [GeV]0 50 100 150 200 250 300 350 400 450 500

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

Muon Pt [GeV]0 50 100 150 200 250 300 350 400 450 500

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

*Plots shown after pre-selection and QCD estimation (details later)


Object Selection: Jets and EmissT Ω

Jets:Reconstructed using the anti-ktalgorithm with cone size 0.4

Calibrated to the hadronic scale

Required to be central with hightransverse momentum

Energy fraction associated with leading primary vertex (JVF) used toreject pile-up jets

EmissT :

The missing transverse energy (EmissT ) is defined as the negativevector sum of transverse momenta of all the objects in the event

EmissT is reconstructed using the MET RefFinal algorithm

Calorimeter cells used are calibrated individually corresponding to thephysics object to which they are associated1

1My ATLAS ‘service’ work involved the study of the calibration of low-pT objects in the Emiss

T calculation


Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

QCD Multijet Estimation Ω

QCD template method

QCD templates from data

‘Anti-Electrons’: reverse only isolationrequirement‘Anti-Muons’: reverse only transverseimpact parameter significance→ ‘non-pointing’

Subtract W+jets contamination from QCDtemplates

Fit QCD template to data usingMT (`, EmissT ) distribution

Let W/Z+jets normalization float

Before scaling

) [GeV]miss

T(lep,ETM

0 50 100 150 200 250 300 350 400 450 500

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410 DataW+jets

Top

QCDZ+jets

Diboson

ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

After scaling

) [GeV]miss

T(lep,ETM

0 50 100 150 200 250 300 350 400 450 500

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Diboson

ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

Scale Factors eνjj µνjj

QCD 0.30 ± 0.05 0.22 ± 0.05W/Z+jets 1.10 ± 0.01 1.09 ± 0.01


Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

Preselection Yields Ω

Event preselection criteria:

One lepton (e/µ) with pT > 30 GeV

At least two jets with pT > 40 GeV,lead jet pT > 100 GeV

EmissT > 40 GeV

Preselected event yields (errors stat. only)

Process eνjj µνjj

W+jets 37994± 152 45712± 170Z+jets 1270± 16 1802± 17Top 15124± 30 16309± 31Diboson 474± 4 490± 4QCD 929± 36 499± 16Total Bkgd 55792± 160 64812± 174Data 55163 64233G∗Bulk (800 GeV) 55.0± 1.0 44.5± 0.9G∗Bulk (1000 GeV) 8.0± 0.2 6.5± 0.2G∗Bulk (1200 GeV) 1.9± 0.1 1.4± 0.1G∗RS1 (750 GeV) 388.4± 5.8 313.8± 5.1G∗RS1 (1000 GeV) 64.2± 1.0 51.3± 0.9G∗RS1 (1250 GeV) 15.3± 0.3 12.7± 0.2

eνjj

Avg Int per Xing2 4 6 8 10 12 14 16 18 20

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

µνjj

Avg Int per Xing2 4 6 8 10 12 14 16 18 20

(dat

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


Data/MC preselection plots Ω

eνjj µνjj

) [GeV]miss

T(lep,E

Tp

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(800GeV)kkG(1000GeV)kkG(1200GeV)kkG

ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

) [GeV]miss

T(lep,E

Tp

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

(j,j) [GeV]T

p0 100 200 300 400 500 600 700

(dat

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410DataW+jetsTopZ+jetsQCDDiboson


ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

(j,j) [GeV]T

p0 100 200 300 400 500 600 700

(dat

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

Signal (W+jets) Control Region Ω

W+jets control region definition:

Preselection Criteria

pT (`,EmissT ) > 200 GeV

pT (jj) > 200 GeV

M(jj) < 65 or M(jj) > 115 GeV


W+jets 4004± 44 3572± 43Z+jets 123± 5 132± 5Top 1135± 8 951± 8Diboson 40± 1 37± 1QCD 74± 15 69± 5Total Bkgd 5376± 48 4760± 44Data 5404± 0.0 4743± 0.0

Signal control region yields (errors stat. only)

eνjj µνjj

M(jj) [GeV]

50 100 150 200 250 3000

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MC backgrounds

G* (750 GeV)

M(jj) [GeV]

50 100 150 200 250 3000

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200

250

300

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MC backgrounds

G* (750 GeV)


Signal Control Region Sidebands Ω

Use the M(jj) sidebands to scale W/Z+jets background to data.

M(jj) < 65 GeV

jj) [GeV]νM(l0 500 1000 1500 2000 2500

signif

icanc

e

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ts

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Data 2011W+jetsTopZ+jetsDibosonQCD

jj) [GeV]νM(l500 1000 1500 2000 2500

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ts

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310Data 2011W+jetsTopZ+jetsQCDDiboson

jj) [GeV]νM(l500 1000 1500 2000 2500

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ts

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310Data 2011W+jetsTopZ+jetsQCDDiboson

W/Z+jets SF 1.11 ± 0.02

M(jj) > 115 GeV

jj) [GeV]νM(l500 1000 1500 2000 2500

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310Data 2011W+jets

Top

Z+jets

QCD

Diboson

W/Z+jets SF 1.02 ± 0.01

Average W/Z+jets SF 1.02 ± 0.03

W/Z+jets MC is scaled by average SF in signal (control) region.


Analysis Outline

Analysis Strategy

Data/MC Samples



Event Preselection


Signal Region

Signal Region Ω

Signal region definition:

Preselection criteria

pT (`,EmissT ) > 200 GeV

pT (jj) > 200 GeV

65 <M(jj) < 115 GeV


W+jets 698± 20 594± 21Z+jets 14± 2 15± 2Top 614± 6 516± 5Diboson 76± 2 63± 1QCD 18± 6 16± 2Total Bkgd 1420± 22 1204± 22Data 1453 1328GBulk (800 GeV) 44.0± 0.9 34.9± 0.8GBulk (1000 GeV) 4.0± 0.1 3.6± 0.1GBulk (1200 GeV) 0.5± 0.0 0.4± 0.0GRS1 (750 GeV) 208.2± 4.3 162.8± 3.7GRS1 (1000 GeV) 21.8± 0.6 18.3± 0.5GRS1 (1250 GeV) 3.4± 0.1 3.1± 0.1

Signal region yields (errors stat. only)

eνjj

jj) [GeV]νM(l0 200 400 600 800 1000 1200 1400 1600 1800 2000

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DataW+jetsTopDibosonQCDZ+jets


µνjj

jj) [GeV]νM(l0 200 400 600 800 1000 1200 1400 1600 1800 2000

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Sources of Sytematic UncertaintiesW/Z+jets Scale Factor Uncertainty

Measurement Systematic Uncertainties

Theoretical Systematic Uncertianties

W/Z+jets systematics Ω

To estimate, use low/high dijet mass sideband scale factors as afunction of M(`νjj) as ‘envelope’ of uncertainty.

Modulate applied W/Z+jets scale factor within this ‘envelope’ andmeasure change in M(`νjj) in signal region.

The largest systematic uncertainty is due to uncertainy of W/Z+jetsscale factor.

jj) (M(j,j) > 115GeV or M(j,j) < 65GeV)νM(l

200 400 600 800 1000 1200 1400 1600 1800 2000

V+

jets

Sca

le F

acto

r

0

0.2

0.4

0.6

0.8

1

1.2

1.4

AverageM(jj) < 65M(jj) > 115

Systematic from W/Z+jets scale factor

Sample eνjj µνjj

W+jets+14.45% +14.71%−2.06% −2.23%

Z+jets+14.57% +14.72%−2.08% −2.23%


Systematic Uncertainties Ω

Systematics shown as Average (Min/Max)%

Source Backgrounds (%) Signal (%)

Signal PDFα - 5

Jet Energy Scaleα 10.1 (5.3/17.9) 4.8 (2.5/9.6)

Luminosityα 3.9 3.9Jet Energy Resolutionα 1.6 (0.3/2.9) 1.5 (0.3/3.0)Trigger SFα 1.1 (0.5/1.7) 1.2 (0.6/1.7)Emiss αT 1.1 (0.4/1.6) 0.1 (0.1/0.1)Lepton Energy Scaleα < 1 < 1Lepton Energy Resolutionα < 1 < 1Lepton Reco SFα < 1 < 1Lepton ID SFα < 1 < 1

W/Z+jets SFβ 9.0 (8.8/9.1) -QCDγ 90 (80/100) -

α: Applies to non-W/Z+jets backgrounds onlyβ: Applies to W/Z+jets backgrounds onlyγ: Applies to QCD background only


Theoretical Systematics

Theoretical systematics from uncertainties on cross-section, partondistribution functions (PDFs), and initial/final state radiation (ISR/FSR).

Systematic WW WZ ZZ tt singletop

WW/WZ/ZZ (σ) 5% 7% 5% - -

tt (σ) - - - +7.0%−9.6% -

tt (shape) - - - 8% -

tb+ tqb+ tW (σ) - - - - 8%

tt shape systematic from:

Uncertainty on top quark mass → 3%

ISR/FSR → 5%

Generator: MC@NLO/POWHEG → 2.5%

Parton shower model: HERWIG/PYTHIA → 5%


Final Results and ConclusionsSignal Yields with Systematics

Statistical Analysis

G∗ Exclusion Limits

Conclusions

Future Prospects

Signal Region Yields with Systematics Ω


W+jets 698± 64 594± 57Z+jets 14± 2 15± 2

Top 614+59−86 518+50

−73Diboson 76± 9 63± 8QCD 18± 24 16± 11

Total backgrounds 1420+91−110 1206+77

−94Data 1452 1318Bulk G∗ (800 GeV) 44.0± 3.4 34.9± 2.7Bulk G∗ (1000 GeV) 4.0± 0.3 3.6± 0.3Bulk G∗ (1200 GeV) 0.5± 0.1 0.4± 0.1RS1 G∗ (750 GeV) 208.2± 18.0 163± 12.8RS1 G∗ (1000 GeV) 21.8± 1.7 18.3± 1.5RS1 G∗ (1250 GeV) 3.4± 0.3 3.1± 0.3

Signal region event yields (errors stat. + syst.)

eνjj

jj) [GeV]νM(l0 200 400 600 800 1000 1200 1400 1600 1800 2000

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µνjj

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The greatest deviation from the background prediction occurs atM(eνjj) = 1000 GeV with p-value = 0.14.Lacking evidence for new physics, limits on the hypothetical signalrate are determined with the CLs method.


Statistical Analysis

M(`νjj) distributions are used as inputs to a poisson NegativeLog-Likelihood Ratio (NLLR) test statistic.

Test statistics separates ‘signal-like’ events from ‘background-like’ events

Multiple pseudo-experiments (PEs) are run under background-only (H0) andsignal+background (H1) hypothesis

Relative location of NLLR(data) to NLLR(H0) and NLLR(H1) distributionsquantify exclusion or discovery!

Confidence levels (CL) defined as fractionsof PEs to right of solid line (data)

CLs = CLs+b

CLb

If CLs < 1− 0.95→ excluded at 95% CL

For each mass point, a 95% excluded value of σ ×BR is calculated forbackground median, ±1, 2σ, and data. Then compared to signal σ ×BR.


RS1 G∗ Observed Limits w/ Systematicseνjj+µνjj

[GeV]G*m

600 800 1000 1200 1400

B [pb]

× σ

110

1

10 WW)→

RS1 G*→(pp σ

Expected Limit

σ 1±Expected

σ 2±Expected

Observed limit

[GeV]G*m

600 800 1000 1200 1400

B [pb]

× σ

110

1

10

1 Ldt = 4.7 fb∫

ATLAS

Internal

Lower mass exclusion limits

Expected Observed

G∗RS1 952 GeV 936 GeV


Bulk RS G∗ Observed Limits w/ Systematicseνjj+µνjj

[GeV]G*m

500 600 700 800 900 1000 1100 1200

B [pb]

× σ

210

110

1

10 WW)→

Bulk G*→(pp σ

Expected Limit

σ 1±Expected

σ 2±Expected

Observed limit

[GeV]G*m

500 600 700 800 900 1000 1100 1200

B [pb]

× σ

210

110

1

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1 Ldt = 4.7 fb∫

ATLAS

Internal

Lower mass exclusion limits

Expected Observed

G∗Bulk 749 GeV 714 GeV


G∗ → WW → `νjj Summary

Expected/Observed lower mass limits from RS1 and Bulk RSgravitons:

Signal eνjj eνjj µνjj µνjj Comb. Comb.w/o sys w/ sys w/o sys w/ sys w/o sys w/ sys

RS1 G∗ (exp.) 1017 966 982 907 1065 952Bulk RS G∗ (exp.) 814 728 795 693 838 749

RS1 G∗ (obs.) 928 915 982 934 973 936Bulk RS G∗ (obs.) 818 727 738 631 849 714

This analysis is the first exotic diboson resonance search in the`νjj channel at the LHC.

These are the first limits set on Bulk RS WW decay!

Current best limit on RS1 Graviton to WW (754 → 936 GeV)!

Analysis approved by Exotics group

Paper is in final stage of approval, should be submitted to PRD∼week! (https://cdsweb.cern.ch/record/1456099)


Future Prospects

The future of LHC collisions promises higher energies and luminosities(already collected > 5 fb−1 of 8 TeV data)!

What does this mean for diboson searches?

Increase in signal cross sections

Concurrent increase in backgroundproduction and pile-up!

Highly boosted decay products→ jet merging Mass [GeV]BulkG*

400 600 800 1000 1200 1400 1600

BR

[pb]

×σ

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17 TeV

8 TeV

W

W

W

W

W W

pT(W)~0 pT(W)~M(W) pT(W)≫M(W)

W

W

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W W


W

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W

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W

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W

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W

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W

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W

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W

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Solution: Use merged jets to reduce backgrounds

Much to look forward to at the LHC in 2012 and beyond!


Backups

Object Definitions

Electrons

egammma author 1 or 31,2,1,2,1

|η| < 2.47 w/ crack region excluded1,2,1,2,1

good object quality (el OQ & 1446 == 0)1,2,1

pT > 30 GeV

tight++ electron1,2,1,2,1

|el trackz0pv| < 1 mm2,1,2

impact parameter significance wrt. primary vertex|el trackd0pv/

√el tracksigd0pv| < 102,1,2

IsolationCaloIsoCorrection::GetPtNPVCorrectedIsolation

etcone30 corrected < 6 GeV2

Jets and EmissT

AntiKt4TopoEMJets (EM + JES)1,2,1,2,1

pT > 40 GeV, |ηEM | < 2.8

LOOSER jet cleaning requirements

|JVF| > 0.751,2,1,2,1

MET RefFinal within |ηcl| < 4.91,2,2

Muons

STACO combined muons1,2,2,1

pT > 30 GeV

|η| < 2.41,2,1,2,1

nBLayerHits > 0 || !expectBLayerHit1,2,1,1

nPixHits + nPixelDeadSensors > 11,2,1,2,1

nSCTHits + nSCTDeadSensors ≥ 61,2,1,2,1

nPixHoles + nSCTHoles < 31,2,1,2,1

TRT extension1,2,1,1

N = nTRTOutliers + nTRTHits

if |η| < 1.9 then require:nTRTOutliers/N < 0.9 && N > 5if |η| > 1.9 && N > 5 then require:nTRTOutliers/N < 0.9

|z0 exPV| < 1 mm2,1,

impact parameter significance2,1,2

|d0 exPV/√cov d0 exPV| < 3

Isolation1,2

CorrectCaloIso::CorrectEtCone30Reletcone30 corrected/pT < 0.14ptcone30/pT < 0.15

SM Higgs SUSY1. W → `ν/Z → `` 1. W → `ν`ν 1. 1 lepton2. EWK (WW ,W/Zγ) 2. W → `νjj


https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/CaloIsolationCorrections

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/HowToCleanJets2011

https://svnweb.cern.ch/trac/penn/browser/schae/MuonIsolationCorrection/tags/MuonIsolationCorrection-00-05

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/WZElectroweakCommonTopics2011

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/HiggsWWlvlvCutWinter2012

https://cdsweb.cern.ch/record/1409740

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/WZElectroweakCommonTopics2011

https://indico.cern.ch/getFile.py/access?contribId=0&resId=0&materialId=slides&confId=191979

https://cdsweb.cern.ch/record/1419168

Data/MC samplesData samples used:

L = 4.701fb−1 from period D-M(OflLumi-7TeV-002)

SM W/Z GRL

NTUP SMWLNUJJ, p833 skims

Egamma and Muons streams

Monte-Carlo samples used:

NTUP SMWZ, r3043 r2993 p833 (mc11c)

Weights applied to MC events to account for pile-up, as well as trigger andreconstruciton efficiencies.

Background cross sections normalized to N(N)LO with k-factors

Backgrounds Generator Cross Sections [pb]

W+jets Alpgen+Herwig/Jimmy 14060Z+jets Alpgen+Herwig/Jimmy 1070WW/WZ/ZZ Herwig+Jimmy 44.9/18.5/5.96Top (tt and st) MC@NLO+Herwig/Jimmy 164, 83.93

Signals (M = 500 -1500) Generator

G∗RS1 → `νjj PythiaG∗bulk → `νjj CalcHEP+Atlfast IIW ′ → `νjj Pythia


http://atlasdqm.web.cern.ch/atlasdqm/grlgen/StandardModel/WZjets_allchannels_v4/

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/WWSemileptonMeasurement#New_lnujj_skimming_slimming

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/ExtendedPileupReweighting

Data/MC samples: Alpgen W+jets reweighting

W+jets is the dominant background

It has been observed that ALPGEN W+jets samples over-estimate thebackground in high W pT regimes

However Sherpa W+jets MC backgrounds match the data betterthan the Alpgen samples in these regions

eνjj

-1L dt ~ 4.71 pb0i eAW

Sherpa

0 100 200 300 400 500 600 700 800 900 1000

Dat

a / M

C

00.20.40.60.8

11.21.41.61.8

2

Eve

nts

-210

-110

1

10

210

310

410

510

610

710

Truth Pt of W Boson 2 1 0

-1L dt ~ 4.71 pb0i eAW

AlpgenSherpa

Truth pT of W Boson [GeV] Generator-level pT of W Boson [GeV]

Even

ts

SH

ERPA

/ALP

GEN

107

105

103

101

10-1

2

1

0

µνjj

-1L dt ~ 4.71 pb0iµ AW

Sherpa

0 100 200 300 400 500 600 700 800 900 1000

Dat

a / M

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00.20.40.60.8

11.21.41.61.8

2

Eve

nts

-210

-110

1

10

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310

410

510

610

710

Truth Pt of W Boson 2 2 0

-1L dt ~ 4.71 pb0iµ AW

AlpgenSherpa

Truth pT of W Boson [GeV]

107

105

103

101

10-1

2

1

0

Even

ts

SH

ERPA

/ALP

GEN

Generator-level pT of W Boson [GeV]

Comparison of Alpgen and Sherpa W+jets generator-level W pT

Due to the fact that Sherpa samples were not available withsufficient statistics, the solution:

→ reweight Alpgen W+jets to match Sherpa generator-level W pTE. Williams (Columbia U.) G∗ → WW → `νjj thesis defense July 2nd, 2012 44 / 41

pT (`, EmissT ), ALPGEN→ SHERPA truth W pT reweighting

W/out Reweighting With Reweighting

eνjj

µνjj

Pt(lep+met)0 100 200 300 400 500 600 700

sign

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Pt(lep+met)0 100 200 300 400 500 600 700

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= 7 TeVs-1 Ldt = 4.701 fb∫

Pt(lep+met)0 100 200 300 400 500 600 700

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Pt(lep+met)0 100 200 300 400 500 600 700

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


pdijetT , ALPGEN→ SHERPA truth W pT reweighting


eνjj

µνjj

(j,j) [GeV]T

p0 100 200 300 400 500 600 700

sign

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

(j,j) [GeV]T

p0 100 200 300 400 500 600 700

sign

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jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

(j,j) [GeV]T

p0 100 200 300 400 500 600 700

sign

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

(j,j) [GeV]T

p0 100 200 300 400 500 600 700

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


EmissT , ALPGEN→ SHERPA truth W pT reweighting


eνjj

µνjj

MEt [GeV]0 100 200 300 400 500 600

sign

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-0.5

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

MEt [GeV]0 100 200 300 400 500 600

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jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

MEt [GeV]0 100 200 300 400 500 600

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

MEt [GeV]0 100 200 300 400 500 600

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


pleptonT , ALPGEN→ SHERPA truth W pT reweighting


eνjj

µνjj

Lepton Pt [GeV]0 50 100 150 200 250 300 350 400 450 500

sign

ifica

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-0.5

0

0.5

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

Lepton Pt [GeV]0 50 100 150 200 250 300 350 400 450 500

sign

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-0.5

0

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Diboson

ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

Lepton Pt [GeV]0 50 100 150 200 250 300 350 400 450 500

sign

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

Lepton Pt [GeV]0 50 100 150 200 250 300 350 400 450 500

sign

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


MT (`, EmissT ), ALPGEN→ SHERPA truth W pT reweighting


eνjj

µνjj

) [GeV]miss

T(lep,ETM

0 50 100 150 200 250 300 350 400 450 500

sign

ifica

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-0.5

0

0.5

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Diboson

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

) [GeV]miss

T(lep,ETM

0 50 100 150 200 250 300 350 400 450 500

sign

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-0.5

0

0.5

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Diboson

ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

) [GeV]miss

T(lep,ETM

0 50 100 150 200 250 300 350 400 450 500

sign

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-0.5

0

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

) [GeV]miss

T(lep,ETM

0 50 100 150 200 250 300 350 400 450 500

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


N jets, ALPGEN→ SHERPA truth W pT reweighting


eνjj

µνjj

Jet N2 4 6 8 10 12

sign

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-0.5

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0.5

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

Jet N2 4 6 8 10 12

sign

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jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

Jet N2 4 6 8 10 12

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫

Jet N2 4 6 8 10 12

sign

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


plead jetT , ALPGEN→ SHERPA truth W pT reweighting


eνjj

µνjj

Lead Jet Pt [GeV]0 100 200 300 400 500 600 700

sign

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ATLAS Internal

jjν e→X

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Lead Jet Pt [GeV]0 100 200 300 400 500 600 700

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

Lead Jet Pt [GeV]0 100 200 300 400 500 600 700

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ATLAS Internal

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= 7 TeVs-1 Ldt = 4.701 fb∫

Lead Jet Pt [GeV]0 100 200 300 400 500 600 700

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


psecond jetT , ALPGEN→ SHERPA truth W pT reweighting


eνjj

µνjj

Second Jet Pt [GeV]0 100 200 300 400 500 600 700

sign

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ATLAS Internal

jjν e→X

= 7 TeVs-1 Ldt = 4.701 fb∫

Second Jet Pt [GeV]0 100 200 300 400 500 600 700

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= 7 TeVs-1 Ldt = 4.701 fb∫

Second Jet Pt [GeV]0 100 200 300 400 500 600 700

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ATLAS Internal

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Second Jet Pt [GeV]0 100 200 300 400 500 600 700

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ATLAS Internal

jjνµ →X

= 7 TeVs-1 Ldt = 4.701 fb∫


tt Control Region Definition and Yields

tt control region is used to check tt agreement in high-pT region.

tt control region definition:

≥ 2 b-tagged jets w/ pT > 40 GeV

pT (jj) > 200 GeV

M(jj) < 65 GeV or M(jj) > 115 GeV


tt 295± 17 279± 16Non− tt 23± 4 19± 4Data 301± 17 301± 17

RS1 G∗ (M = 1 TeV) 0± 0 0± 0

tt control region yields (errors stat. only)

) [GeV]T

miss(ETP

0 50 100 150 200 250 300

sig

nific

an

ce

3

1.5

0

1.5

30 50 100 150 200 250 300

10

20

30

40

50

60Data

)+Xtt(+HF+Xν l→W+Xν l→W

+X

l+l→*

γZ/γVV+V

Multijet WW (M=1 TeV)→G* WZ (M=1 TeV)→W’

1 Ldt = 4701.39 pb∫

) [GeV]T

miss(l , ETM

0 50 100 150 200 250

sig

nific

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ce

3

1.5

0

1.5

30 50 100 150 200 250

10

20

30

40

50

60

70

80Data

)+Xtt(+HF+Xν l→W+Xν l→W

+X

l+l→*

γZ/γVV+V

Multijet WW (M=1 TeV)→G* WZ (M=1 TeV)→W’

1 Ldt = 4701.39 pb∫


Impact Parameter   Distance between the point of closest approach of a track and primary vertex   Transverse IP d0 is this distance in transverse plane x,y

  d0 significance = |d0|/(σ(d0))1/2

  Longitudinal IP z0 is the z-coordinate of this point

W+jets QCD contamination

Goal is to estimate, and correct for, the amount of W+jets events in QCDtemplate. This method assumes that e→ jet ∼ jet→ e.

i) Create W+jets ‘contamination’ samples by running over W+jets MCwith QCD ‘anti-lepton’ requirements:

electrons: Reverse calorimeter isolation (etcone 30 > 6 GeV)muons: Reverse ‘pointing’ (|d0sig| > 3 GeV)

ii) Scale W+jets contamination template with W+jets cross-section andlumi to get estimated distribution of W+jets events in QCD template

iii) Subtract W+jets contamination template from un-scaled QCDtemplate

iv) Scale new QCD template from fit to data



QCD ∼ 18% W+jets in eνjj QCD ∼ 7% W+jets in µνjj

) [GeV]miss

T(e,ETM

0 50 100 150 200 250 300 350 400 450 500

1

10

210

310Unscaled QCD

W+jets contamination

) [GeV]miss

T,Eµ(TM

0 50 100 150 200 250 300 350 400 450 500

1

10

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310Unscaled QCD

W+jets contamination

) [GeV]miss

T(e,ETM

0 50 100 150 200 250 300 350 400 450 500

1

10

210

310QCD w/out W+jets sub

QCD w/ W+jets sub

) [GeV]miss

T,Eµ(TM

0 50 100 150 200 250 300 350 400 450 500-110

1

10

210 QCD w/out W+jets sub

QCD w/ W+jets sub



With outW+jetssubtraction

With W+jetssubtraction

eνjj µνjj

) [GeV]miss

T(lep,ETM

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ATLAS Internal

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`νjj QCD Estimationeνjj µνjj

W/out

QCD

scaling

) [GeV]miss

T(lep,ETM

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With

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) [GeV]miss

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ATLAS Internal

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Scale Factors eνjj µνjj

QCD 0.30 ± 0.05 0.22 ± 0.05V+jets 1.10 ± 0.01 1.09 ± 0.01


`νjj QCD Estimation

QCD distributions before and after scaling.

eνjj µνjj

mT(e,MET) [GeV]

0 50 100 150 200 250 300 350 400 450 500

1

10

210

No QCD scaling

After QCD scaling

mT(mu,MET) [GeV]

0 50 100 150 200 250 300 350 400 450 500

1

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210

No QCD scaling

After QCD scaling


Preselection Definition

Reject event if:dR(`, jet) < 0.4Contains any looser bad jets

Jets found in LAr hole (simple veto)Data, require pT > 40× (1−BCH CORR JET)/(1−BCH CORR CELL)MC, require pT > 40 GeV, only applied to fraction of MC eventscorresponding to affeted data lumi (∼ 17%)

Has noise burst with LArError = 2Fails QCD triangle cut

Require:Lepton trigger:

Data Run Electron MuonPeriod Range Trigger Trigger

D-J 179710→ 186755 EF e20 medium EF mu18 MG or EF mu40 MSonly barrelK 186873→ 187815 EF e22 medium EF mu18 MG medium or EF mu40 MSonly barrelL-M 188902→ 191933 EF e22vh medium1 EF mu18 MG medium or

EF mu40 MSonly barrel medium

First primary vertex has Ntrack >= 3

→ Only one lepton (e/µ) with pT > 30 GeV→ At least two jets with pT > 40 GeV

→ Lead jet pT > 100 GeV→ Emiss

T > 40 GeVE. Williams (Columbia U.) G∗ → WW → `νjj thesis defense July 2nd, 2012 60 / 41

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/HowToCleanJets2011

https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/HowToCleanJets2011#Simple_veto

https://twiki.cern.ch/twiki/bin/viewauth/Atlas/LArEventVetoRel17

Signal Significance

The ultimate goal of an experimental search for a new particle is to state whether or nota statistically significant observation of the signal has been made. In other words, toanswer the canonical question:

Given the data, is it possible to distinguish between two hypotheses?

Three main steps toward answering this question:

1 Define a test-statistic which optimizes theseparation of the signal+backgroundhypothesis (H1) and the background-onlyhypothesis (H0)

2 Run an appropriate number ofpseudo-experiments (Frequentist) for bothhypothesis, incorporating all signal andbackground nuisance parameters (systematics)in a coherent way (Bayesian).

3 Define confidence levels designating exclusionsor discoveries 2012 Higgs → γγ 4.7fb−1 result


https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2011-161/

1) Define test-statistic: Likelihood-Ratio

Neyman-Pearson lemma suggests that the most powerful test forstatistically separating two point hypotheses is the likelihood-ratiotest, that is:

Λ =L(s+ b|x)

L(b|x)

s = signalb = backgroundx = dataL = likelihood

Rate of signal or background events follow a Poisson distribution,appropriate choice for likelihood functional form:

L(s+ b) =(s+ b)xe−(s+b)

x!, L(b) =

(b)xe−b

x!


http://www.jstor.org/stable/91247

1) Define test-statistic: Likelihood-Ratio

With this choice, combining likelihoods from multiple channels (e.g. X → Y andX → Z) as well as from multiple bins within a discriminating variable (e.g.M(X)) is natural:

Λ(x) =

channels∏i

bins∏j

(sij + bij)xij e−(sij+bij)

xij !/

(bij)xij e−(bij)

xij !.

In the high-statistics limit the distributions of -2 ln Λ are expected to converge to(χ2s+b − χ2

b), thus it is more common to use:

NLLR(x) = −2 ln(Λ(x))

= −2

channels∑i

bins∑j

[sij − xij ln

(1 +

sijbij

)]

This test statistic decreases monotonically for increasingly signal-like (decreasinglybackground-like) experiments. Can be used to order data outcomes relative toeach other in hypothesis significance


2) Pseudo-Experiments: A Semi-Frequentist Approach

Assuming that the data is drawn randomly from a Poisson parent distribution, wecan create pdfs of NLLR(x) for both the signal+background hypothesis (H1) andthe background-only (H0) hypothesis, by conducting pseudo-experiments

Systematic uncertainties (nuisance parameters) are incorporated by sampling abifurcated Gaussian distribution with the ±σ uncertainties estimated for eachsource (hence ‘Semi’-Frequentist)

The pseudo-experiment background (Bmj ) and signal (Smj ) yields are then given as:

Bmj = B0,mj (1 +

Nbkgdsys∑i

gbkgdi )

Smk = S0,mk (1 +

Nsigsys∑i

gsigi )

Where B0,m (S0,m) is the nominal background (signal) poisson yield for channel j (k)and bin m. gbkgd (gsig) is the contribution from systematic uncertainty i.



Running O(20k) pseudo-experiments, we evaulate the NLLR distributions underthe H0, NLLR(x = Db), and H1, NLLR(x = Ds+b), hypotheses. Where:

Db =

Nbins∑m

Nb∑j

Bmj , Ds+b =

Nbins∑m

(

Nb∑j

Bmj +

Ns∑k

Smk )

N

-2ln(Λ(x))

Bkgd Only

Sig + Bkgd



Running O(20k) pseudo-experiments, we evaulate the NLLR distributions underthe H0, NLLR(x = Db), and H1, NLLR(x = Ds+b), hypotheses. Where:

Db =

Nbins∑m

Nb∑j

Bmj , Ds+b =

Nbins∑m

(

Nb∑j

Bmj +

Ns∑k

Smk )

N

-2ln(Λ(x))

Bkgd Only

Sig + Bkgd

NLLR(xdata)

Location of measured data on NLLR pdf (Prior Predictive Ensemble) used toquantify exclusion/discovery


3) Modified Frequentist Confidence Levels: CLs

Confidence levels defined as the fraction of outcomes predicted to falloutside of the specified confidence interval

CLs+b: fraction of H1 pseudo-experiments less signal-like than data

CLs+b = Ps+b(X ≥ Xobs) =

∫ ∞NLLR(x=Dobs)

P(x = Ds+b) dP

CLb: fraction of H0 pseudo-experiments less signal-like than data

CLb = Pb(X ≥ Xobs) =

∫ ∞NLLR(x=Dobs)

P(x = Db) dP

Therefore...

High CLs+b → data signal-like. (otherwise, used for exclusion)High CLb (or low 1− CLb) → data not background like.

For discovery, (1-CLb) ≡ p-value = the probability, under H0 hypothesis, that backgroundfluctuated to produce observed signal. Typically require (1-CLb) < 5σ(4.3× 10−7) toclaim discovery



N

-2ln(Λ(x))

Bkgd Only

Sig + Bkgd

NLLR(xdata)

1-CLb

CLs+b

Therefore...

High CLs+b → data signal-like. (otherwise, used for exclusion)High CLb (or low 1− CLb) → data not background like.

For discovery, (1-CLb) ≡ p-value = the probability, under H0 hypothesis, that backgroundfluctuated to produce observed signal. Typically require (1-CLb) < 5σ(4.3× 10−7) toclaim discovery



The strictly frequentist CLs+b confidence level, while a powerfulstatistical tool, is unstable if the background model dramaticallydisagrees with the data:

Background overestimated → low CLs+b → possible exclusion!Background underestimated → high CLs+b → possible discovery!

The solution: The modified frequentist confidence level, CLs

CLs ≡CLs+b

CLb

Normalizing CLs+b with CLb removes the dependence on backgroundmodelling and leads to more conservative limits on H1 hypothesis, aswell as lower false exclusion rate (type II error) than nominal (1− CL)

A signal model is then excluded at or above95% confidence level if CLs ≤ 0.05


`νjj Signal Systematics

Acceptance systematics for ‘bulk’ Randal-Sundram GRS(M = 700 GeV) sample.

Systematic eνjj [%] µνjj [%]JES 2.83 2.63JER 0.90 0.99LES 0.06 0.07LER 0.06 0.08All Clusters 0.10 0.06Met PileUp 0.03 0.07ID SF 0.85 0.04Reco SF 0.91 0.39Trigger SF 0.55 1.74Iso SF 2.00 1.00Signal PDF 5.00 5.00Luminosity 3.90 3.90V+jets 0.00 0.00

Total 7.40 7.23

Muon energy resolution chosen as ’worst’ smearing between ID and MS.


`νjj Background Systematics

Table: eνjj percent ∆ acceptance.

Systematic Wjets Zjets TTBar Single Diboson QCDTop

JES (10.99) (18.04) 4.78 8.37 10.33 -JER (1.14) (6.96) 0.06 1.39 3.13 -LES (0.1) (0.8) 0.18 0.08 0.05 -LER (0.42) (1.59) 0.14 0.07 0.08 -All Clusters (0.51) (1.56) 0.91 1.25 1.69 -Met PileUp (0.45) (2.13) 0.78 0.85 1.72 -ID SF (0.96) (0.92) 0.89 0.88 0.89 -Reco SF (0.81) (0.83) 0.88 0.88 0.8 -Trigger SF (0.56) (0.53) 0.56 0.56 0.59 -Iso SF (2) (2) 2 2 2 -Luminosity - - 3.9 3.9 3.9 -MJ Normalization - - - - - 80.0V+jets 5 5.11 - - - -

Total 5 5.11 6.74 9.76 12.28 80.0


`νjj Background Systematics

Table: µνjj percent ∆ acceptance.

Systematic Wjets Zjets TTBar Single Diboson QCDTop

JES (10.75) (9.08) 7.3 9.41 10.48 -JER (0.27) (7.57) 0.63 1.55 5.45 -LES (0.4) (0.86) 0.08 0.58 0.3 -LER (1.21) (2.37) 0.79 0.14 0.37 -All Clusters (0.29) (0.49) 0.42 0.64 1.96 -Met PileUp (0.12) (0.84) 0.43 0.72 1.91 -ID SF (0.04) (0.04) 0.04 0.04 0.04 -Reco SF (0.39) (0.41) 0.37 0.38 0.39 -Trigger SF (1.71) (1.75) 1.74 1.73 1.74 -Iso SF (1) (1) 1 1 1 -Luminosity - - 3.9 3.9 3.9 -MJ Normalization - - - - - 100.0V+jets 5.23 5.34 - - - -

Total 5.23 5.34 8.6 10.5 14.2 100.


Signal Control Region Plots (after scaling) Ω

eνjj µνjj

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`νjj Signal Control Region Plots

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* MC uncertainty (Lumi and W/Z+jets scale factor systematic) not included in significance



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`νjj signal templates

Fully simulated signal samples only available with masses:

M(G∗RS1) = 500− 1500 GeV, in 250 GeV steps

andM(G∗Bulk) = 500− 1500 GeV, in 100 GeV steps

To account for possibility of missing a signal with an intermediate mass value, aset of G∗RS1 and G∗Bulk signal templates were made, spanning the full mass rangein steps of 50 GeV.

`νjj mass from full-sim samples fit with Crystal Ball function:

N ·

exp− (x−x)2

2σ2 for x−xσ > −a

A · (B − x−xσ )−n for x−x

σ ≤ −a

where A = ( n|a| )n · exp− |a|

2

2 , and B = n|a| − |a|


`νjj signal template fits

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Full-simulated G∗ samples (eνjj) with crystal ball functional fit for masses 500 GeV

(upper-left), 750 GeV (upper-right), 1000 GeV (middle-left), 1250 GeV (middle-right) and

1500 GeV (bottom row).E. Williams (Columbia U.) G∗ → WW → `νjj thesis defense July 2nd, 2012 78 / 41

`νjj signal template parameter extraction

To create ‘in-between’ mass template points, the crystal ball fitparameters, as well as the signal acceptances are interpolated through a fitacross the signal mass range.The mean x, width σ and a parameters extracted and their trend are fittedwith simple functions:

x(x) = p0 + p1x (1)

σ(x) = p0 + p1x (2)

a(x) =p0

p1x2+ p2x (3)

n = 2 (4)

Parameter n fixed to 2, shape of the tail can be appropriately controlledsolely by the a parameter.Acceptance extrapolated through a Landau distribution which empiricallyfits the curve.


`νjj signal template parameter fits

G* Pole Mass [GeV]

400 600 800 1000 1200 1400 1600

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stal

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n

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3

Fits of crystal ball parameters across full-simulated G∗ → eνjj vs M(G∗)shown. From left to right and top to bottom are the obtained fits for thex, σ, a, and n.


`νjj signal template acceptance fit

G* Pole Mass [GeV]

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Landau functional fit (in black) to the acceptances in the eνjj channelusing to the full-simulated G∗ samples (in blue) with masses 500, 750,1000, and 1500 GeV . Acceptances of template signal distributions wereextrapolated from fit.


`νjj signal template cross-sections

Table: Summary of cross-sections times branching ratio and acceptances perchannel used to derive cross section limits at intermediate MG∗ mass values,where fully simulated samples were non available.

G∗ Mass σ × B Acceptance[GeV] [pb] eνjj µνjj Average

500 5.593 0.045 0.034 0.040550 4.597 0.065 0.048 0.057600 3.601 0.081 0.058 0.070650 2.643 0.089 0.065 0.077700 1.648 0.091 0.067 0.079750 0.614 0.089 0.068 0.079800 0.514 0.082 0.064 0.073850 0.413 0.075 0.059 0.067900 0.313 0.067 0.054 0.061950 0.212 0.060 0.049 0.0551000 0.027 0.051 0.041 0.0461050 0.095 0.047 0.040 0.0441100 0.078 0.041 0.036 0.0391150 0.061 0.036 0.032 0.0341200 0.044 0.032 0.029 0.0311250 0.027 0.030 0.027 0.0291300 0.023 0.026 0.023 0.0251350 0.019 0.023 0.021 0.0221400 0.015 0.021 0.019 0.0201450 0.012 0.018 0.017 0.0181500 0.008 0.018 0.018 0.018


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Gkk → WW → `νjj signal templates

eνjj µνjj

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1

10

210Mass [GeV]

500550600650700750800850900950100010501100115012001250130013501400145015001550

jj) [GeV]νM(l

0 200 400 600 800 1000 1200 1400 1600 1800 2000-410

-310

-210

-110

1

10

210Mass [GeV]

500550600650700750800850900950100010501100115012001250130013501400145015001550

Reconstructed M(`νjj) from AFII ‘bulk’ Graviton samples: 500-1500 GeV, 100 GeV stepsplotted with signal templates for 550-1550 GeV in 100 GeV steps


`νjj signal variable

Plot shown in `νjj signal region

MT (sys)

M(sys)

eνjj

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Eve

nts

-110

1

10

210

310mc.alpgen.wjets, 1119.70mc.mcatnlo.top, 707.66mc.herwig.vv, 93.17qcd.alpgen, 44.18mc.alpgen.zjets, 25.59mc.rsg.m500.kmpl0, 1238.45mc.rsg.m1000.kmpl0, 28.69mc.rsg.m1500.kmpl0, 0.70

= 7 TeVs-1

Ldt = 4.701 fb∫

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Eve

nts

-110

1

10

210

310mc.alpgen.wjets, 1119.70mc.mcatnlo.top, 707.46mc.herwig.vv, 93.10qcd.alpgen, 44.18mc.alpgen.zjets, 25.59mc.rsg.m500.kmpl0, 1238.45mc.rsg.m1000.kmpl0, 28.69mc.rsg.m1500.kmpl0, 0.70

= 7 TeVs-1

Ldt = 4.701 fb∫

µνjj

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Eve

nts

-110

1

10

210

310 mc.alpgen.wjets, 867.96mc.mcatnlo.top, 544.23mc.herwig.vv, 72.11qcd.alpgen, 50.44mc.alpgen.zjets, 26.09mc.rsg.m500.kmpl0, 918.70mc.rsg.m1000.kmpl0, 22.49mc.rsg.m1500.kmpl0, 0.68

= 7 TeVs-1

Ldt = 4.701 fb∫

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Eve

nts

-110

1

10

210

310 mc.alpgen.wjets, 867.47mc.mcatnlo.top, 544.30mc.herwig.vv, 71.94qcd.alpgen, 50.44mc.alpgen.zjets, 26.09mc.rsg.m500.kmpl0, 918.55mc.rsg.m1000.kmpl0, 22.49mc.rsg.m1500.kmpl0, 0.68

= 7 TeVs-1

Ldt = 4.701 fb∫

Mass distributions look better, especially for signal masses> 1 TeV


G∗/W ′ → `νjj truth comparison plots

M = 500 GeV M = 1000 GeV

G*/W' pt [GeV]

0 50 100 150 200 250 300 350 400 450 500-410

-310

-210

-110G*

KKGW'

G*/W' pt [GeV]

0 50 100 150 200 250 300 350 400 450 500

-310

-210

-110G*

KKGW'

*)θcos(

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 10

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

G*KKG

W'

*)θcos(

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 10

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

G*KKG

W'



M = 500 GeV M = 1000 GeV

G*/W' #m

300 350 400 450 500 550 600 650 700

-410

-310

-210

-110

G*KKG

W'

G*/W' #m

800 850 900 950 1000 1050 1100 1150 1200

-310

-210

-110

G*KKG

W'



M = 500 GeV M = 1000 GeV

W/Z boson pt [GeV]

0 50 100 150 200 250 300 350 400 450 500-410

-310

-210

-110 G*kkG

W'

W/Z boson pt [GeV]

0 100 200 300 400 500 600 700 800 900 1000-510

-410

-310

-210

-110 G*kkG

W'

ηW/Z boson

-5 -4 -3 -2 -1 0 1 2 3 4 5

-410

-310

-210

-110 G*kkG

W'

ηW/Z boson

-5 -4 -3 -2 -1 0 1 2 3 4 5

-410

-310

-210

-110 G*kkG

W'



M = 500 GeV M = 1000 GeV

lepton pt [GeV]

0 50 100 150 200 250 300 350 400 450 500

-410

-310

-210

-110G*

KKGW'

lepton pt [GeV]

0 100 200 300 400 500 600 700 800

-410

-310

-210

-110G*

KKGW'

ηlepton

-5 -4 -3 -2 -1 0 1 2 3 4 5

-410

-310

-210

-110 G*KKG

W'

ηlepton

-5 -4 -3 -2 -1 0 1 2 3 4 5

-410

-310

-210

-110 G*KKG

W'



M = 500 GeV M = 1000 GeV

lepton pt [GeV]

0 50 100 150 200 250 300 350 400 450 500

-410

-310

-210

-110G*

KKGW'

lepton pt [GeV]

0 50 100 150 200 250 300 350 400 450 500

-210

G*KKG

W'



M = 500 GeV M = 1000 GeV

quark pt [GeV]

0 50 100 150 200 250 300 350 400 450 500

-410

-310

-210

-110G*

KKGW'

quark pt [GeV]

0 100 200 300 400 500 600 700 800

-410

-310

-210

-110G*

KKGW'

ηquark

-5 -4 -3 -2 -1 0 1 2 3 4 5-510

-410

-310

-210

-110G*

KKGW'

ηquark

-5 -4 -3 -2 -1 0 1 2 3 4 5

-410

-310

-210

-110 G*KKG

W'


G∗/W ′ → `νjj Acceptances

M = 500 GeV M = 1000 GeV

Selection Cut0 1 2 3 4 5 6 7 8

Acc

epta

nce

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 W'G*

KKG


Acc

epta

nce

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 W'KKG

G*


/G*)

KK

Rel

ativ

e A

ccep

tanc

e (G

1

1.5

2

2.5

3

3.5


/G*)

KK

Rel

ativ

e A

ccep

tanc

e (G

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

Cut 2: Lepton pt/etaCut 3: Jet pt/etaCut 4: EmissT

Cut 5: Pt(lepton,EmissT )Cut 6: Pt(dijet)Cut 7: M(dijet)


`νjj Signal Region Plots

eνjj µνjj

(j,j) [GeV]T

p0 100 200 300 400 500 600 700 800 900 1000

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210

310DataW+jetsTopDibosonQCDZ+jets


(j,j) [GeV]T

p0 100 200 300 400 500 600 700 800 900 1000

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj

(j,j) [GeV]T

p0 100 200 300 400 500 600 700 800 900 1000

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210

310 DataW+jetsTopDibosonZ+jetsQCD




eνjj µνjj

Lepton Pt [GeV]0 100 200 300 400 500 600 700 800

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



Lepton Pt [GeV]0 100 200 300 400 500 600 700 800

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj

Lepton Pt [GeV]0 100 200 300 400 500 600 700 800

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210





eνjj µνjj

[GeV]misstE

0 100 200 300 400 500 600 700

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



[GeV]misstE

0 100 200 300 400 500 600 700

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj

[GeV]misstE

0 100 200 300 400 500 600 700

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210





eνjj µνjj

(lep,MET)TM0 50 100 150 200 250 300 350 400 450 500

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



(lep,MET)TM0 50 100 150 200 250 300 350 400 450 500

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj

(lep,MET)TM0 50 100 150 200 250 300 350 400 450 500

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210





eνjj µνjj

)miss

T(lep,E

Tp

0 100 200 300 400 500 600 700 800 900 1000

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



)miss

T(lep,E

Tp

0 100 200 300 400 500 600 700 800 900 1000

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj

)miss

T(lep,E

Tp

0 100 200 300 400 500 600 700 800 900 1000

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210





eνjj µνjj

Jet Pt [GeV]Σ200 400 600 800 1000 1200 1400 1600 1800

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210

310 DataW+jetsTopDibosonQCDZ+jets


Jet Pt [GeV]Σ200 400 600 800 1000 1200 1400 1600 1800

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj

Jet Pt [GeV]Σ200 400 600 800 1000 1200 1400 1600 1800

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210

310DataW+jetsTopDibosonZ+jetsQCD




eνjj µνjj

Jet Pt [GeV]ΣMET + Lepton Pt + 400 600 800 1000 1200 1400 1600 1800 2000

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210




sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj


sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210





eνjj µνjj

dR(jj)0.4 0.6 0.8 1 1.2 1.4

sign

ifica

nce

-2

0

2

Eve

nts

50

100

150

200

250

300 DataW+jetsTopDibosonQCDZ+jets


dR(jj)0.4 0.6 0.8 1 1.2 1.4

sign

ifica

nce

-2

0

2

Eve

nts

50

100

150

200



eνjj + µνjj

dR(jj)0.4 0.6 0.8 1 1.2 1.4

sign

ifica

nce

-2

0

2

Eve

nts

100

200

300

400

500

DataW+jetsTopDibosonZ+jetsQCD




eνjj µνjj

dPhi(jet,jet)0 0.5 1 1.5 2 2.5

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



dPhi(jet,jet)0 0.5 1 1.5 2 2.5

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210



eνjj + µνjj

dPhi(jet,jet)0 0.5 1 1.5 2 2.5

sign

ifica

nce

-2

0

2

Eve

nts

-110

1

10

210

310DataW+jetsTopDibosonZ+jetsQCD



`νjj p-values

Mass eνjj µνjj Combined

500 0.604 0.172 0.381550 0.489 0.222 0.353600 0.374 0.206 0.286650 0.315 0.147 0.22700 0.368 0.121 0.223750 0.511 0.191 0.34800 0.69 0.393 0.559850 0.662 0.643 0.675900 0.454 0.706 0.608950 0.209 0.612 0.403

1000 0.14 0.451 0.2711050 0.183 0.352 0.2711100 0.208 0.327 0.2831150 0.182 0.329 0.273

The probabilities, or p-value ≡ 1 - CLb, that the background fluctuates to or above the data ineach channel. p-values for M≥ 1200 GeV are statistics limited and not reliable. Systematicuncertainties are included in this calculation.


search for excited randall-sundrum gravitons from warped extra dimensions with semi-leptonic diboson...

Technology

g w w jj thesis defensejuly

g w w jj thesis defenseg

atlas detector atlas

analysis jj

highpt w boson

hadronically jj

event selectionsignal

detector simulation