Overview of SM/QCD Physics at ATLAS

OVERVIEW OF SM/QCD PHYSICS AT ATLAS.

James Robinson

on behalf of the ATLAS Collaboration

HEPMAD 16, Antananarivo, Madagascar13–18th October 2016

The Large Hadron Collider

pp

ATLAS

ALICE

CMS

LHCb

The Large Hadron Collider

pp

ATLAS

ALICE

CMS

LHCb

The ATLAS detector

> General purpose detector - study proton collisions or heavy ions

> Full cylindrical coverage around the interaction pointJ.E.M. Robinson | Overview of SM/QCD Physics at ATLAS | 14/10/16 | Page 2/30

Proton-proton collisions at ATLAS

Day in 2016

20/04 18/05 15/06 13/07 10/08 07/09 05/10

]-1

Tot

al In

tegr

ated

Lum

inos

ity [f

b

0

5

10

15

20

25

30

35

40 = 13 TeVs ATLAS Online LuminosityLHC Delivered

ATLAS Recorded

-1Total Delivered: 31.9 fb-1Total Recorded: 29.5 fb

7/16 calibration

> 40 million events per second> Use multi-level trigger system

to reduce to O(1000)

> Average number ofinteractions per event:

∼14 (2015)∼23 (2016)

Mean Number of Interactions per Crossing

0 5 10 15 20 25 30 35 40 45 50

/0.1

]-1

Del

iver

ed L

umin

osity

[pb

0

20

40

60

80

100

120

140=13 TeVsOnline, ATLAS -1Ldt=22.4 fb∫

> = 13.7µ2015: <

> = 23.2µ2016: <

> = 21.4µTotal: <

7/16 calibration

J.E.M. Robinson | Overview of SM/QCD Physics at ATLAS | 14/10/16 | Page 3/30

Standard Model overview

> Matter consists ofquarks and leptons

> Interactions betweenthem occur via forcecarrying gauge bosons

> Most recently Higgsboson discovered in2012 by ATLAS andCMS Collaborations;

Hugely successful but unable to explain some phenomena


Particle detection with ATLAS


Jet: (collimated particlesfrom quark/gluon)energy deposits in bothcalorimeter systems

Photon: energy clustersin EM calorimeterwithout matching track

Electron: energy clustersin EM calorimeter withmatching ID track

Muon: matching tracksin the ID and muontracker

Tau: narrow jet withmatching tracksMET: (missing transverseenergy) pT required tobalance all observedobjects



































Tau: narrow jet withmatching tracks

MET: (missing transverseenergy) pT required tobalance all observedobjects







Tau: narrow jet withmatching tracks

MET: (missing transverseenergy) pT required tobalance all observedobjects

Cross section and luminosity

> Cross section quantifiesprobability that collidingparticles will interact

> Units of area → analogous toclassical geometric crosssection

> Lint = N/σ is a measure of theamount of data collected


Introduction to the Standard Model

The importance of QCD

J.E.M. Robinson | Introduction to the Standard Model | 14/10/16 | Page 7/30

Hard-scatter

Hadronisationmodelling

Beam-remnants,primordial kT

Parton-shower(initial- andfinal-stateradiation)

Multiple-partoninteractions,

underlying event

QCD (strong interaction) involved at many scales in each event



Hard-scatter





underlying event




Hard-scatter





underlying event




Hard-scatter





underlying event




Hard-scatter





underlying event




Hard-scatter





underlying event




Hard-scatter





underlying event


Why make Standard Model measurements?

> Accurate QCD predictions are crucial:Multiple different scales in the same event topologyTest predictions in unprobed phase space and kinematic regimesUnderstanding of dominant backgrounds for BSM searches

> Constraints on modelsInputs for parton distribution functions (PDFs)Information for further tuning of tools such as MC generators

> Measure fundamental SM parameters:New measurements can improve on current precisionSensitivity to SM processes that have not yet been observed

Need to understand the SM before extending knowledge beyond it


Different aspects of the Standard Model

Personal choice of what to show: full list of ATLAS results here

> Soft QCDinelastic cross section, elastic/total cross section, low pT minimumbias, underlying event

> PDF constraintsinclusive jet, multijet, W/Z cross sections and ratios, high-massDrell-Yan and prompt photon

> Constraints on perturbative QCDZ+jets, DPI in 4-jet events, bb̄ cross section, charged particlesinside jets, Zϕ∗, W angular distributions

> Electroweak sectordiboson cross sections, Z+photons

> Top physicsCovered in Kevin’s talk


https://twiki.cern.ch/twiki/bin/view/AtlasPublic

Soft QCD

Inelastic pp cross section at 13 TeV arXiv:1606.02625

> Non-perturbative QCD → cannot be calculated> Trigger with scintillating counters> Select events with ξ > M2

X/s > 10–6

MBTSn

2 4 6 8 10 12 14 16 18 20 22 24

MB

TS

ndev

ents

nd ev

ents

n1

2−10

1−10

1

Data Pythia8 SS

= 0.06εPythia8 DL, = 0.085εPythia8 DL,

= 0.10εPythia8 DL, MBR

EPOS LHC QGSJET-II

ATLAS-1bµ13 TeV, 60.1

Inclusive selection

MBTSn2 4 6 8 10 12 14 16 18 20 22 24

MC

/dat

a

0.5

1

1.5

[GeV]s

210 310 410

[mb]

inel

σ30

40

50

60

70

80

90

100ATLAS (MBTS)ATLAS (ALFA)TOTEMALICELHCbAugerpp (non-LHC)

pp

Pythia 8EPOS LHCQGSJET-II

ATLAS 7000 8000 9000 10000 11000 12000 13000

65

70

75

80LHC region

> Constrain extrapolation using previous measurements at 7 TeV

J.E.M. Robinson | Soft QCD | 14/10/16 | Page 10/30

Total and elastic pp cross sections at 8 TeV PLB (2016) 158

> Detect small-angle elastic scatters with ALFA detector> Measure in terms of momentum transfer t =

[(θ∗x )2 + (θ∗y )2

]p2

]2-t [GeV

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

]2 [m

b/G

eVt

/delσd

1

10

210

310

2012 data

Elastic fit

ATLAS

-1bµ=8 TeV, 500s

]2 [GeV-t0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

(Fit-

data

)/da

ta

-0.1-0.05

00.05

0.1

Total errorStatistical

(b)

0.02 0.04 0.06

150

200

250

300

350

400

> σtot = 4π Im[fel

(t → 0

)]

[GeV]s10 210 310 410

[mb]

σ

0

50

100

150

200

250

totσ

elσ

ATLASTOTEM

ppLower energy ppLower energy

Cosmic raysCOMPETE HPR1R2

)s(2) + 0.14 lns12.7 - 1.75 ln(

(a)

7000 7200 7400 7600 7800 800092

94

96

98

100

102

104


Track-based minimum bias at 13 TeV PLB (2016) 758, EPJC 76 (2016) 502

> Charged particle distributions test non-perturbative models

10 20 30 40 50

chn /

dev

N

d⋅ ev

N1/

7−10

6−10

5−10

4−10

3−10

2−10

1−10

1

10

DataPYTHIA 8 A2PYTHIA 8 MonashEPOS LHCQGSJET II-04

| < 0.8η| > 500 MeV, T

p 1, ≥ chn > 300 psτ

= 13 TeVsATLAS

chn10 20 30 40 50

MC

/ D

ata

0

0.5

1

1.5

2

> Compare variousgenerators/models

[GeV]s

310 410

| < 0

.2

η| η /

dch

N d⋅

evN

1/

1

2

3

4

5

6

7

1≥ chn

> 500 MeV,

Tp

2≥ chn

> 100 MeV,

Tp

6≥ chn

> 500 MeV,

Tp

ATLAS

> 30 ps (extrapolated)τ

DataPYTHIA8 A2PYTHIA8 MonashEPOS LHCQGSJET II-04

> Agreement across range of energies


Underlying event 13 TeV ATL-PHYS-PUB-2015-019

> Any hadronic activity notassociated to hardscatter

> Measure in azimuthalregions wrt referenceobject

5 10 15 20 25 30

> [G

eV]

φ dη

/dT

pΣ2<

d

0

0.5

1

1.5

2

2.5 PreliminaryATLAS

= 13 TeVs

Transverse region

|< 2.5η > 0.5 GeV, |T

p

> 1 GeV leadT

p

DATA (uncorrected) EPOS

PYTHIA 8 A14 PYTHIA 8 A2HERWIG++ EE5 PYTHIA 8 Monash

[GeV]leadT

p5 10 15 20 25 30

MC

/Dat

a

0.70.80.9

11.11.21.3

> Transverse region has bestdistinguishing power


PDF constraints

Inclusive jet cross section at 13 TeV ATLAS-CONF-2016-092

[GeV]T

p210 310

[pb/

GeV

]y

dT

p/dσ2 d

-2310

-2010

-1710

-1410

-1110

-810

-510

-210

10

410

710

1010

1210PreliminaryATLAS

-113 TeV, 3.2 fb

=0.4R jets, tanti-k

uncertaintiesSystematic

EW corr.×Non-pert. corr. ×NLOJET++ (CT14nlo)

)0 10×| < 0.5 (y|

)-3 10×| < 1.0 (y |≤0.5

)-6 10×| < 1.5 (y |≤1.0

)-9 10×| < 2.0 (y |≤1.5

)-12 10×| < 2.5 (y |≤2.0

)-15 10×| < 3.0 (y |≤2.5

Relative uncertainty of 2.1% on the integrated luminosity not included

> Compare tofixed-order NLOcalculations

> Data/theoryagreement withinuncertainties for mostPDF sets

2103

10

0.8

1

1.2| < 0.5y|

2103

10

0.8

1

1.2| < 1.0y |≤0.5

[GeV]T

p210 310

0.8

1

1.2

1.4 | < 1.5y |≤1.0

2103

10

0.8

1

1.2

1.4| < 2.0y |≤1.5

2103

10

1

1.5

2 | < 2.5y |≤2.0

[GeV]T

p210 310

1

2

3 | < 3.0y |≤2.5

The

ory

/ dat

a

The

ory

/ dat

a

PreliminaryATLAS

= 13 TeVs

-1 dt = 3.2 fbL ∫

=0.4R jets, tanti-k

NLOJET++max

Tp =

Rµ =

Fµ

EW corr.Non-pert and

Data

MMHT 2014

CT14

NNPDF 3.0

2103

10

0.8

1

1.2| < 0.5y|

2103

10

0.8

1

1.2| < 1.0y |≤0.5

[GeV]T

p210 310

0.8

1

1.2

1.4 | < 1.5y |≤1.0

2103

10

0.8

1

1.2

1.4| < 2.0y |≤1.5

2103

10

1

1.5

2 | < 2.5y |≤2.0

[GeV]T

p210 310

1

2

3 | < 3.0y |≤2.5

The

ory

/ dat

a

The

ory

/ dat

a

PreliminaryATLAS

= 13 TeVs

-1 dt = 3.2 fbL ∫

=0.4R jets, tanti-k

NLOJET++max

Tp =

Rµ =

Fµ

EW corr.Non-pert and

Data

2.0HERAPDF

CT10

= 5fnABM12

J.E.M. Robinson | PDF constraints | 14/10/16 | Page 14/30

Multijet cross sections at 8 TeV JHEP 12 (2015) 105

) [f

b/G

eV

](1

)

T /

d(p

σd

410

310

210

110

1

10

210

310

410

510

610

Data

0.6)×Pythia 8 (

1.4)×Herwig++ (

1.1)×MadGraph+Pythia (

>100 GeV(1)

Tp

ATLAS1 20.3 fb1=8 TeV, 95 pbs

[GeV](1)

Tp

210×23

103

10×2

Th

eo

ry/D

ata

0

0.5

1

1.5

2

systematic uncertainty

Total experimental

) [f

b/G

eV

](1

)

T /

d(p

σd

410

310

210

110

1

10

210

310

410

510

610

Data

0.9)×HEJ (

1.0)×BlackHat/Sherpa (

1.0)×NJet/Sherpa (

>100 GeV(1)

Tp

ATLAS1 20.3 fb1=8 TeV, 95 pbs

[GeV](1)

Tp

210×23

103

10×2

Th

eo

ry/D

ata

0

0.5

1

1.5

2


Total experimental

uncertainty

PDF)⊕NLO (scale

> NLO predictions generally describe data better than LO

4j/mmin

2jm

0 0.1 0.2 0.3 0.4

) [f

b/b

in w

idth

]4

j/m

min

2j

/ d

(mσ

d

210

310

410

510

610

710

810

910ATLAS

1 20.3 fb1=8 TeV, 95 pbs

Data

0.9)×HEJ (

1.0)×BlackHat/Sherpa (

1.0)×NJet/Sherpa (

>500 GeV4jm

>1000 GeV4jm

>1500 GeV4jm

>2000 GeV4jm


Total experimental

PDF) uncertainty⊕NLO (scale

Th

eo

ry/D

ata

0

0.5

1

1.5

2

Th

eo

ry/D

ata

0

0.5

1

1.5

2

Th

eo

ry/D

ata

0

0.5

1

1.5

2

4j/mmin

2jm

0 0.1 0.2 0.3 0.4

Theory

/Data

0

0.5

1

1.5

2

> mmin2j /m4j probes range

of scales in the event


W and Z cross sections at 13 TeV PLB 759 (2016) 601

> Agreement withNNLO QCD +NLO EW

> Uncertaintiescancel in ratio

fid )m

eas

σ/pr

edσ(

0.85

0.9

0.95

1

1.05

1.1

1.15ATLAS

-113 TeV, 81 pb

(inner uncert.: PDF only)

Z±W+W-

W

experimental uncertainties⊕luminosity

experimental uncertainties

MMHT14nnlo68CLNNPDF3.0CT14nnloABM12ATLAS-epWZ12nnloHERAPDF2.0nnlo

-Wfidσ / +W

fidσ1.2 1.22 1.24 1.26 1.28 1.3 1.32 1.34

ATLAS-113 TeV, 81 pb

total uncertainty±data stat. uncertainty±data

ABM12CT14nnloNNPDF3.0MMHT14nnlo68CLATLAS-epWZ12nnloHERAPDF2.0nnlo

-Wfidσ / +W

fidσ = -/W+WR> W+/W- sensitive to u and d

PDF differences at low x> W/Z can constrain

strange-quark sea


High-mass Drell-Yan 13 TeV JHEP 08 (2016) 009

> Off-shell measurements dominatedby coupling to γ (sensitive to new physics)

[GeV]ll

m

[p

b/G

eV

]ll

md

σd

310

210

110

w/o luminosity uncer.

Data

Sys. uncertainty

Total uncertainty

ATLAS

Th

eo

ry/D

ata

0.95

1

1.05 MMHT2014 w/o PI corrections

) + scale + PI unc.sαMMHT2014 with 68% CL (PDF +

[GeV]ll

m

200 300

Th

eo

ry/D

ata

0.9

1

1.1 MMHT2014

HERAPDF2.0 CT14 ABM12 NNPDF3.0

116

1 = 8 TeV, 20.3 fbs

> PI process (γγ → ℓℓ)significant at large mℓℓ

> Sensitivity to PIcorrections

Parton momentum fraction x

310 210 110 1

)2

(x,Q

γ x

0

0.02

0.04

0.06

0.08

0.1 ATLASATLAS 2 GeV4 = 10

2Q

NNPDF2.3qed 68% CLNNPDF2.3qed + ATLAS highmass DY dataMRST2004qed, current quark massMRST2004qed, constituent quark massCT14qed 68% CL

> Data significantlyconstrains photon PDF


Inclusive isolated prompt photon cross section at 8 TeVJHEP 06 (2016) 005

> Experimental uncertaintygenerally smaller than thetheoretical one

> Improved phase-spacecoverage and precisioncompared to previousmeasurements [GeV]γ

TE30 40 100 200 300 1000

[pb/

GeV

]γ T

/ dE

σd

-1110

-1010

-910

-810

-710

-610

-510-410

-310

-210-1101

10210

310

410

510 )0| < 0.6 (x 10γη |≤0

Data 2012

-1 = 8 TeV, 20.2 fbs

ATLAS

CT10HOXPETNLO: J

)-2| < 1.37 (x 10γη |≤0.6 )-4| < 1.81 (x 10γη |≤1.56 )-6| < 2.37 (x 10γη |≤1.81

[GeV]γTE

100 1000

Sys

tem

atic

Unc

.

0.60.70.80.9

11.11.21.31.4

ATLAS

[GeV]γTE

100 1000

Sta

tistic

al U

nc.

0.60.70.80.9

11.11.21.31.4

ATLAS

ATLAS|<0.6γη |-12010 880nb

|<0.6γη |-12010 35pb|<1.37γη |-12011 4.6fb

|<0.6γη |-12012 20.2fb


Constraints on perturbative QCD

Z+jets cross sections at 13 TeV ATLAS-CONF-2016-046

> BLACKHAT (fixed-order NLO)good for distributionssensitive to single jet

> ALPGEN and MADGRAPHCKKW (LO ME+PS) model toohard a jet spectrum

> SHERPA and MADGRAPH FxFx(NLO ME+PS) improve this

> Recent Njetti (NNLO) describesjet pT and HT well

(leading jet)jet

y

0 0.5 1 1.5 2 2.5

[pb]

je

t y

/dσd

210

ATLAS Preliminary1−13 TeV, 3.16 fb

jets, R = 0.4tanti-k

< 2.5jet

y > 30 GeV, jet

Tp

1 jet≥) + −l+ l→*(γZ/ Data

NNLOjetti

1 jet N≥ Z + HERPAS + ATHLACK B

2.1HERPA S6YP + LPGEN A

8 CKKWLYP + MG5_aMC8 FxFxYP + MG5_aMC

(leading jet)jet

y

0 0.5 1 1.5 2 2.5

Pre

d./D

ata

0.8

1

1.2

(leading jet)jet

y

0 0.5 1 1.5 2 2.5

Pre

d./D

ata

0.8

1

1.2

(leading jet)jet

y

0 0.5 1 1.5 2 2.5

Pre

d./D

ata

0.8

1

1.2

J.E.M. Robinson | Constraints on perturbative QCD | 14/10/16 | Page 19/30

DPI in 4-jet events at 7 TeV (to JHEP) arXiv:1608.01857

> Extract complete-DPSand semi-DPScomponents withneural network

cDPSξ

32 +

sDPSξ

31

Ent

ries/

0.05

210

310

410

510 ATLAS

-1 = 7 TeV, 37 pbs

< 0.1sDPS

ξ ≤0.0

cDPSξ

32 +

sDPSξ

31

0 0.2 0.4 0.6 0.8 1

Fit/

Dat

a

0.60.8

11.21.4

Exp

erim

ent (

ener

gy, f

inal

sta

te, y

ear)

[mb]effσ

0 5 10 15 20 25 30

ATLASATLAS (

√s = 7 TeV, 4 jets, 2016)

CDF (√s = 1.8 TeV, 4 jets, 1993)

UA2 (√s = 630 GeV, 4 jets, 1991)

AFS (√s = 63 GeV, 4 jets, 1986)

DØ (√s = 1.96 TeV, 2γ+ 2 jets, 2016)

DØ (√s = 1.96 TeV, γ+ 3 jets, 2014)

DØ (√s = 1.96 TeV, γ+ b/c + 2 jets, 2014)

DØ (√s = 1.96 TeV, γ+ 3 jets, 2010)

CDF (√s = 1.8 TeV, γ+ 3 jets, 1997)

ATLAS (√s = 8 TeV, Z + J/ψ, 2015)

CMS (√s = 7 TeV, W+ 2 jets, 2014)

ATLAS (√s = 7 TeV, W+ 2 jets, 2013)

DØ (√s = 1.96 TeV, J/ψ + Υ, 2016)

LHCb (√s = 7&8 TeV, Υ(1S)D0,+, 2015)

DØ (√s = 1.96 TeV, J/ψ + J/ψ, 2014)

LHCb (√s = 7 TeV, J/ψΛ+

c , 2012)

LHCb (√s = 7 TeV, J/ψD+

s , 2012)

LHCb (√s = 7 TeV, J/ψD+, 2012)

LHCb (√s = 7 TeV, J/ψD0, 2012)

> Compatible with model of σeff asprocess-independent


Charged particle multiplicity in jets at 7 TeV EPJC 76(6) (2016) 1-23

> Dijet topology: pT1/pT2 < 1.5> Ghost matching associates

tracks to jets

[GeV]T

Jet p500 1000 1500

⟩ fo

rwar

dch

arge

d -

nce

ntra

l

char

ged

n⟨

-2

0

2ATLAS

-1 = 20.3 fbint

= 8 TeV, Ls

> 0.5 GeVtrack

Tp

Data (with stat. uncertainty)

syst. uncert.⊕Data stat.

.175 AU2 CT10Pythia 8

.186 A14 NNPDF2.3Pythia 8

2.7.1 EE5 CTEQ6L1Herwig++

⟩ ch

arge

d n⟨

0

5

10

15

20

25ATLAS

> 2 GeVtrack

Tp

| < 2.1jet

Tη|

-1 L dt = 20.3 fb∫ = 8 TeV s

(with stat. uncertainty)Data syst. uncert.⊕ stat. Data

2.6.3 EE3 CTEQ6L1Herwig++ 2.7.1 EE5 CTEQ6L1Herwig++

.175 AU2 CT10Pythia 8

.186 A14 NNPDF2.3Pythia 8

.186 Monash NNPDF2.3Pythia 8

.428 P2012 CTEQ6L1Pythia 6

.428 P2012 RadHiPythia 6

.428 P2012 RadLoPythia 6

[GeV]T

Jet p0 500 1000 1500

Dat

a/M

odel

0.8

1

1.2

> Input for MC tuning


bb̄ cross section at 7 TeV arXiv:1607.08430

�✁✂✄☎✆✝✞✟✠✡

☛

☞☛☛

✌☛☛

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✮ ✖✖✕ ✯✙✰✱✲✤✤

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✴✵

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✹✺✻✼✷∑✽✾ ✿ ✾ ❀✿ ❀✾ ❁✿

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✿❈✾

❀

❀❈✾

❉❊❋ ●❍■❏ ❑▲▼ ◆❖P◗

> Extract bb̄ withtemplate fit

�✁✂✄☎✆✝✞

✟✠✡✡

☛☞✌✄✍✁

✂✂

→

✎✁✁

σ

✍ ✏−✑✒

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★✩ ✪✩✩ ✪★✩ ✫✩✩ ✫★✩ ✬✩✩ ✬★✩

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✿❀❁❂❃❄❅✿❆❇❂❈❉ ❊

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SHERPA 1.43

> Flavour creation dominates over gluonsplitting at ∆R ∼ π

> Modelling is worst for low b-jet pT


Z/γ ϕ∗η at 13 TeV EPJC 76(5) (2016) 1-61

ϕ∗ = tan(π–∆ϕ

2

)sin

(θ∗η)

cos(θ∗η)

= tanh(η+–η–

2

)> Only depends on angles

between leptons

η*φ

-310 -210 -110 1 10

η*φ/dσ

dσ1/

-410

-310

-210

-110

1

10

210ATLAS -1 = 8 TeV, 20.3 fbs

| < 2.4ll

< 66 GeV, |yll m≤46 GeV

ee-channel

-channelµµCombined

Statistical uncertainty

Total uncertainty

η

*φ-310 -210 -110 1 10

Com

bine

dC

hann

el

0.95

1

1.05

/NDF = 54 / 362χ

η

*φ

-310 -210 -110 1 10

]σP

ull [

-202

> Correlated with pTZ/Mℓℓ

η

*φ-310 -210 -110 1 10

0.8

1

1.2

| < 2.4ll


η

*φ-310 -210 -110 1 10

0.8

0.9

1

1.1

| < 2.4ll


η

*φ-310 -210 -110 1 10

0.6

0.8

1

1.2

| < 2.4ll


Data - statistical uncertainty Data - total uncertaintyHERPAS (AU2)YTHIAPOWHEGP

(AZNLO)YTHIAPOWHEGP ERWIGHOWHEGP

ATLAS -1 = 8 TeV, 20.3 fbs

Mon

te C

arlo

/ D

ata

η*φ/dσ

dσ1/

> Best agreement at low massJ.E.M. Robinson | Constraints on perturbative QCD | 14/10/16 | Page 23/30

W-boson angular distributions at 8 TeV arXiv:1609.07045R

) [fb]

∆/d

(σ

d

20

40

60

80

100

120

140

160

180 1 = 8 TeV, 20.3 fbs

Data

ALPGEN+PYTHIA6 W+jets

PYTHIA8 W+j & jj+weak shower

SHERPA+OpenLoops W+j & W+jj

NNLOjetti

1 jet N≥W +

> 500 GeVT

Leading Jet p

ATLAS

0 0.5 1 1.5 2 2.5 3 3.5 4

Pre

d./

Da

ta

0.5

1

1.5

2

, closest jet)µR(∆

0 0.5 1 1.5 2 2.5 3 3.5 4

Pre

d./

Da

ta

0.5

1

1.5

2

> W → µν plus at least one jet> NLO QCD+EW prediction

from SHERPA +OPENLOOPS> NNLO calculation of

W+ ≥ 1jet from Njetti →implications for processeswith real W emission


Electroweak physics

WW cross section at 13 TeV ATLAS-CONF-2016-090

> Measurement in theeµ decay channel

Eve

nts

/ 5

Ge

V

0

50

100

150

200

250 Data

stat)⊕ SM (sys WW Top Quark DrellYan W+jets Diboson

ATLAS Preliminary1 = 13 TeV, 3.16 fbs

, SRν

±

µν±e→WW

[GeV]T

Leading lepton p

20 40 60 80 100 120

Data

/ S

M

0.6

0.8

1

1.2

1.4

> Suppress topbackground withb-jet veto

[fb]WWfid

σ

300 400 500 600 700

Data

11 fb ± 50 ± 20 ±529

stat.

stat.+syst.+lumi.

(fixedorder acceptance)nNNLO+H calculation

(MC acceptance)nNNLO+H calculation

ATLAS Preliminary 1 = 13 TeV, 3.16 fbs

ν

±

µ ν± e→WW

Fiducial cross section

> Good agreement with NNLO theoreticalprediction

J.E.M. Robinson | Electroweak physics | 14/10/16 | Page 25/30

WZ cross sections at 13 TeV PLB 762 (2016) 1; ATLAS-CONF-2016-043 [

fb]

fid.

σ∆

1

10

210

Data

Powheg+Pythia

Sherpa

ATLAS

1 = 13 TeV, 3.2 fbs

ν →Z ±W ℓ′ ℓℓ

jetsN

0 1 2 3 4

Ratio to P

ow

heg

1

2

3

4

5

≥

> Final states with three e/µ> Fiducial cross sections

differential in pT and mass

theoryZ±W

σ / fid.Z±W

σ0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

combined

µµµ

µµe

eeµ

eeeATLAS Preliminary

Data

Powheg+PythiaCT10

-1 = 13 TeV, 13.3 fbs

Z±W

0.21±1.16

0.14±1.11

0.18±1.18

0.10±1.29

0.09±1.24

> Small excess wrt. NLOPOWHEG +PYTHIA


ZZ cross section at 13 TeV PRL 116, 101801 (2016)

> ZZ → 4ℓ gives a clean signal(stats dominated)

theoryσ/dataσ0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2

Measurement

Tot. uncertainty

Stat. uncertainty

prediction2sα

σ 1±

σ 2±

Theory: PLB 750 (2015) 407CT10 NNLO

Combined

4µ

2 µe2

4e

ATLASFiducial

4l→ ZZ →pp

-1 = 13 TeV, 3.2 fbs

[TeV] s0 2 4 6 8 10 12 14

[pb]

to

tZ

Zσ

02468

1012141618202224

)pZZ (p

ZZ (pp)=13 TeV)sLHC Data 2015 (

=8 TeV)sLHC Data 2012 (

=7 TeV)sLHC Data 2011 (

=1.96 TeV)sTevatron Data (

-1 66-116 GeV) 3.2 fbll

llll (m→ATLAS ZZ

-1 66-116 GeV) 19.6 fbll

llll (m→CMS ZZ

-1 66-116 GeV) 4.6 fbll

) (mνν ll(ll/→ATLAS ZZ-1 60-120 GeV) 5.0 fb

ll llll (m→CMS ZZ

-1) (on-shell) 9.7 fbνν ll(ll/→CDF ZZ-1 60-120 GeV) 8.6 fb

ll) (mνν ll(ll/→D0 ZZ

ATLAS MCFM, CT14 NLO

> Fiducial and total crosssections agree well with NLOprediction from MCFM


Zγ and Zγγ production at 8 TeV PRD 93, 112002 (2016)

> Z → ℓℓ (including neutrinos)> ISR/FSR plus triple/quartic

couplings

[fb/

GeV

]γ- l

+ ldm

)γ- l+ l

→(p

pσd

-410

-310

-210

-110

1

10

210

-1 = 8 TeV, 20.3 fbs

0≥jetsN channelγ-l+l

ATLAS

Data

Sherpa (CT10)

MCFM (CT10)

NNLO (MMHT2014)

[GeV]γ-l+lm

D

ata

The

ory

0.6

0.81

1.2

1.4

50 86 96 110 135 170 210 270 350 470 640 2000

[TeV]FFΛ

3 4 5 6 7 8

]-4

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4Λ/

M2

f

-100

-80

-60

-40

-20

0

20

40

60

80

100310×

Data observedMC expected

σ 2±σ 1±

Unitarity bounds

Allowed

channelsγγ and eeγγµµ, γγνν

ATLAS-1=8 TeV, 20.3 fbs

> Limits on BSM form-factorsof anomalous couplings

> No deviations from SMexpectations seen


Conclusions

Standard Model measurements at ATLAS∫L dt

[fb−1]Reference

WZjjEWK 20.3 PRD 93, 092004 (2016)

W±W±jjEWK 20.3 PRL 113, 141803 (2014)

Wγγ 20.3 PRL 115, 031802 (2015)

Zγγ 20.3 PRD 93, 112002 (2016)

ZjjEWK 20.3 JHEP 04, 031 (2014)

t̄tγ 4.6 PRD 91, 072007 (2015)

t̄tZ 20.3 JHEP 11, 172 (2015)

3.2 ATLAS-CONF-2016-003

t̄tW 20.3 JHEP 11, 172 (2015)

3.2 ATLAS-CONF-2016-003

Zγ4.6

PRD 87, 112003 (2013)arXiv:1407.1618 [hep-ph]

20.3PRD 93, 112002 (2016)arXiv:1407.1618 [hep-ph]

Wγ 4.6PRD 87, 112003 (2013)arXiv:1407.1618 [hep-ph]

ts−chan 20.3 PLB 756, 228-246 (2016)

ZZ4.6 JHEP 03, 128 (2013)

20.3 ATLAS-CONF-2013-020

3.2 PRL 116, 101801 (2016)

WZ4.6 EPJC 72, 2173 (2012)

20.3 PRD 93, 092004 (2016)

3.2 arXiv:1606.04017 [hep-ex]

Wt2.0 PLB 716, 142-159 (2012)

20.3 JHEP 01, 064 (2016)

3.2 ATLAS-CONF-2016-065

γγ 4.9 JHEP 01, 086 (2013)

WW4.6 PRD 87, 112001 (2013)

20.3 CERN-EP-2016-186

3.2 ATLAS-CONF-2016-090

tt−chan4.6 PRD 90, 112006 (2014)

20.3 ATLAS-CONF-2014-007

3.2 ATLAS-CONF-2015-079

t̄t4.6 EPJC 74: 3109 (2014)

20.3 EPJC 74: 3109 (2014)

3.2 arXiv:1606.02699 [hep-ex]

Z 0.035 PRD 85, 072004 (2012)

3.2 ATLAS-CONF-2016-046

W 0.035 PRD 85, 072004 (2012)

0.081 PLB 759 (2016) 601

γ4.6 PRD 89, 052004 (2014)pT > 100 GeV

20.2 arXiv: 1605.03495 [hep-ex]pT > 25 GeV

Dijets R=0.4 4.5 JHEP 05, 059 (2014)0.3 < mjj < 5 TeVJets R=0.4 4.5 JHEP 02, 153 (2015)0.1 < pT < 2 TeV

pp8×10−8 Nucl. Phys. B, 486-548 (2014)

50×10−8 arXiv:1607.06605

σ [pb]10−4

10−3

10−2

10−1 1 10

110

210

310

410

510

610

11

data/theory0.5 1 1.5 2 2.5

Theory

LHC pp√s = 7 TeV

Datastatstat ⊕ syst

LHC pp√s = 8 TeV


LHC pp√s = 13 TeV


Standard Model Production Cross Section Measurements Status: August 2016

ATLAS Preliminary

Run 1,2√s = 7, 8, 13 TeV

Agreement with predictions over 15 orders of magnitude!

J.E.M. Robinson | Conclusions | 14/10/16 | Page 29/30

Summary

> Numerous SM measurements performed by ATLAS(only a selection shown here)

> Uncertainties and correlations propagated throughout> ATLAS data provide constraints on PDF and theoretical models> No significant discrepancies from SM seen

More measurements to come!

J.E.M. Robinson | Conclusions | 14/10/16 | Page 30/30

Backup

ATLAS coordinates

> ATLAS uses a right-handed coordinate system> The origin is at the nominal interaction point and the z-axis

along the beam pipe> The x-axis points from the IP to the centre of the LHC ring, and

the y-axis points upward.> Cylindrical coordinates (r,ϕ) are used in the transverse plane, ϕ

being the azimuthal angle around the beam pipe> The pseudorapidity is defined in terms of the polar angle θ asη = ln tan (θ/2).

J.E.M. Robinson | Backup | 14/10/16 | Page 1/23

Detector performance

Detector component Resolution η coverage

Tracking σpT/pT ∼ 0.05%pT ⊕ 1% |η| < ±2.5

EM calorimeters σE/E ∼ 10%√

E ⊕ 0.7% |η| < ±3.2Hadronic calorimeters…barrel and end-cap σE/E ∼ 50%

√E ⊕ 3% |η| < ±2.7

…forward σE/E ∼ 100%√

E ⊕ 10% 3.1 < |η| < 4.9Muon spectrometer σpT

/pT ∼ 10% at pT = 1 TeV |η| < ±2.7

NB. Energy and transverse momentum in GeV


Jet calibration in ATLAS

Jet: collimated flowof particlesoriginating from aquark or a gluon

Dag Gillberg, Carleton 2012-09-05Jet calibration schemes 6

Calorimeter jets(EM or LCW scale)

Pile-up offset correction Origin correction Energy & !

calibrationResidual in situ

calibration

Calorimeter jets(EM+JES or

LCW+JES scale)

Jet calibration

Changes the jet direction to point to the primary vertex. Does not affect the energy.

Calibrates the jet energy and pseudorapidity to the particle jet scale. Derived from MC.

Residual calibration derived using in situ measurements.Derived in data and MC. Applied only to data.

Corrects for the energy offset introduced by pile-up. Depends on µ and NPV.Derived from MC.

Jet reconstructionjet constituents jets

Local cluster weighting

Calorimeterclusters

(LCW scale)

Calorimeterclusters

(EM scale)

Jet finding Calorimeter jets(LCW scale)

Jet finding Calorimeter jets(EM scale)

Tracks Track jets

Simulatedparticles

Particle jets(aka truth jets)

Calibrates clusters based on cluster properties related to shower development

Jet finding

Jet finding


Data correction to particle level

> Measurements corrected back to particle level using amatrix-based method

transfer matrix relating particle level to reconstructed observabledetermine shape uncertainty in-situ: exploits data/reco MC(perform for several unfolding methods; choose most precise)

> Full propagation of uncertainties and correlations:statistical uncertainty (data and MC) using pseudo-experiments(bootstrap method tracks correlations with other measurements)systematic uncertainties using nuisance parameters(asymmetric uncertainties taken into account)


Inelastic pp cross section at 13 TeV arXiv:1606.02625

Df0.1 0.15 0.2 0.25 0.3 0.35 0.4

SS

R

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18Data 2015Pythia8 SS

=0.085εPythia8 DL, =0.060εPythia8 DL, =0.10εPythia8 DL,

Pythia8 MBREPOS LHCQGSJET-II

ATLAS-1bµ=13 TeV, L=60.1 s

> σfid(ξ > 10–6

)= N–Nbkg

ϵtrig×L ×1–f

ξ>10–6

ϵsel

> Diffractive fraction impacts fξ>10–6


Total and elastic pp cross sections at 8 TeV PLB (2016) 158

0

2000

4000

6000

8000

10000

12000

x(237 m) A-side [mm]-5 -4 -3 -2 -1 0 1 2 3 4 5

x(23

7 m

) C

-Sid

e [m

m]

-5

-4

-3

-2

-1

0

1

2

3

4

5

ATLAS-1bµ=8 TeV, 500 s

(a)

]2 [GeV-t0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

]-2

[GeV

t/d

Nd

210

310

410

510

610

710

ATLAS-1bµ=8 TeV, 500 s

Data arm 1

Antigolden background

DPE background

(b)

σ2tot = 16π(h̄c)2

1+ρ2dσeldt

∣∣∣t=0

]2-t [GeV

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Acc

epta

nce

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Arm 1Arm 2

ATLAS Simulation

=8 TeVs

]2 [GeV-t

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35R

elat

ive

erro

r-0.1

-0.05

0

0.05

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Arm 1Total Statistical

]2 [GeV-t

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Rel

ativ

e er

ror

-0.1

-0.05

0

0.05

0.1

Arm 2TotalStatistical


Track-based minimum bias at 13 TeV PLB (2016) 758, EPJC 76 (2016) 502

Observables measured> Charged particles with a mean lifetime τ > 300 ps

> 1Nev

dNchdη , 1

2πpTNev

d2Nchdη dpT

, 1Nev

dNevdNch

, ⟨pT⟩vs.Nch

Monte Carlo predictions in order of agreement to data1 EPOS: parton-based Gribov-Regge theory (QCD-inspired EFT)2 Pythia: separation into non-diffractive and diffractive (involving

colour-singlet)3 QGSJET-II: Reggeon field theory with “semi-hard” pomerons


Underlying event 13 TeV ATL-PHYS-PUB-2015-019

[rad] wrt lead

φ ∆

|> [G

eV]

φ∆ d

|η

/dT

pΣ2<

d

0

0.5

1

1.5

2

2.5

3

> 5 GeVleadT

p

> 1 GeVleadT

p

|< 2.5η > 0.5 GeV, |T

p

toward transverse away

PreliminaryATLAS

DATA (uncorrected) EPOSPYTHIA 8 A14 PYTHIA 8 A2HERWIG++ EE5 PYTHIA 8 Monash

= 13 TeVs

MC

/Dat

a

0.70.80.9

11.11.21.3

> 5 GeVleadT

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| [rad]φ∆|0 0.5 1 1.5 2 2.5 3

MC

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11.11.21.3

> 1 GeVleadT

p

> Use tracks withpT > 0.5 GeV and|η| < 2.5

> None of the models arevery discrepant fromdata, buildingconfidence in MPIenergy extrapolationmodel


Inclusive jet cross section at 13 TeV ATLAS-CONF-2016-092

> Jet reconstruction with anti-kt R = 0.4> Double differential cross sections as a function of jet pT and |y|> The NLO pQCD predictions calculated with NLOJET++ 4.1.3

interfaced to APPLGRID> Renormalisation and factorisation scale uncertainties> Appropriate PDF uncertainties depending on which set is used

[GeV]T

p

210×2

310

310×2S

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mat

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ncer

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ty (

rela

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al)

0.6

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1.4

1.5

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JER

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Preliminary ATLAS

[GeV]T

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1.3

1.4

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JER

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Preliminary ATLAS


Multijet cross sections at 8 TeV JHEP 12 (2015) 105

> At least four anti-kt R = 0.4 jets with |y| < 2.8 and pT > 64 GeV> No explicit subtraction of DPI (expected to be ∼ 1%)> HEJ, NJET/SHERPA and BLACKHAT/SHERPA describe leading jets> As well as these, MADGRAPH +PYTHIA describes variables

sensitive to wide-angle gluon radiation> HEJ performs worst for rapidity measurements at low pT


W and Z cross sections at 13 TeV PLB 759 (2016) 601

Ent

ries

/ 2 G

eV

0

5

10

15

20

25

30

310×

νe→W ATLAS

-113 TeV, 81 pb

Data

Syst. Unc.⊕MC Stat.

ν e→W

Multijet-e+ e→Z

ντ→W

Other backgrounds

[GeV]T m40 60 80 100 120 140

Dat

a / P

red.

0.80.9

11.11.2

Ent

ries

/ GeV

1

10

210

310

410

510 Data Syst. Unc.⊕MC Stat.

-µ+µ→ZDiboson

-τ+τ→ZTop quarks

-µ+µ→Z ATLAS

-113 TeV, 81 pb

[GeV]µµm70 80 90 100 110

Dat

a / P

red.

0.80.9

11.11.2

-µ+µ →Z σ / -e+ e→Z σ = ZR0.85 0.9 0.95 1 1.05

νµ → ±

Wσ / ν

e→ ±

Wσ =

W

R 0.95

1

1.05


68% CL ellipse area

Data PDG averageWR PDG averageZR

Standard Model

Zfidσ / ±W

fidσ9.4 9.6 9.8 10 10.2 10.4 10.6 10.8


total uncertainty±data stat. uncertainty±data

ABM12CT14nnloNNPDF3.0MMHT14nnlo68CLATLAS-epWZ12nnloHERAPDF2.0nnlo

Zfidσ / ±W

fidσ = W/ZR


High-mass Drell-Yan 13 TeV JHEP 08 (2016) 009

[GeV]e

TE

100 200 300 400 500 600 700 800Data

/Exp.

0.5

1

1.5

Entr

ies

1

10

210

310

410 Data

*γZ/

& Wttt

Multijet & W+Jets

Diboson

Photon induced

ATLAS1 8 TeV, 20.3 fb =s

300 GeV >eem

[GeV]µT

p

100 200 300 400 500 600 700 800Data

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0.5

1

1.5

Entr

ies

1

10

210

310

410 Data

*γZ/

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Multijet & W+Jets

Photon induced

ATLAS1 8 TeV, 20.3 fb =s

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Theory

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1.1 < 150 GeV

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1 = 8 TeV, 20.3 fbs

MMHT2014 w/o PI corrections

) + scale + PI unc.sα(PDF +

MMHT2014 with 68% CL

0.9

1

1.1 < 200 GeV

ll150 GeV < m

0.9

1

1.1 < 300 GeV

ll200 GeV < m

0.9

1

1.1

1.2 < 500 GeV

ll300 GeV < m

|ll

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ll500 GeV < m

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y|

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1

1.1 < 150 GeV

ll116 GeV < m

Data

Sys. uncertainty

Total uncertainty

NNPDF3.0

ABM12

CT14

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|ll

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0 0.4 0.8 1.2 1.6 2 2.4

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1

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ATLAS


Inclusive isolated prompt photon cross section at 8 TeVJHEP 06 (2016) 005

> Photons with EγT > 25 GeV

and |ηγ | < 2.37 (except crackregion)

> PETER (NLO+NNNLL)predictions agree muchbetter than JETPHOX (NLO)

ATLAS-1 = 8 TeV, 20.2 fbs

Data 2012

Systematic Unc.:

CombinedEnergy ScaleAdmixture

Lumi Uncert.

bkgR [GeV]

γTE

30 100 200 1000

Sys

tem

atic

Unc

.

0.8

0.9

1

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1.2

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30 100 200 1000

Sys

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1

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30 100 200 1000

Sys

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0.9

1

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1.2

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Data 2012

Lumi Uncert.NLO:

CT10HOXPETJLO:

YTHIAPHERPAS

| < 0.6γη |≤0 | < 1.37γη |≤0.6 | < 1.81γη |≤1.56 | < 2.37γη |≤1.81

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

0.50.60.70.80.9

11.11.21.31.41.5

| < 0.6γη |≤0 ATLAS

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

0.50.60.70.80.9

11.11.21.31.41.5

| < 1.37γη |≤0.6 ATLAS

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

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11.11.21.31.41.5

| < 1.81γη |≤1.56 ATLAS

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

0.50.60.70.80.9

11.11.21.31.41.5

| < 2.37γη |≤1.81 ATLAS


Data 2012

Lumi Uncert.NLO:

R CT10ETEP CT10HOXPETJ

| < 0.6γη |≤0 | < 1.37γη |≤0.6 | < 1.81γη |≤1.56 | < 2.37γη |≤1.81

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

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11.11.21.31.41.5

| < 0.6γη |≤0 ATLAS

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

0.50.60.70.80.9

11.11.21.31.41.5

| < 1.37γη |≤0.6 ATLAS

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

0.50.60.70.80.9

11.11.21.31.41.5

| < 1.81γη |≤1.56 ATLAS

[GeV]γTE

30 100 200 1000

The

ory

/ Dat

a

0.50.60.70.80.9

11.11.21.31.41.5

| < 2.37γη |≤1.81 ATLAS


Z+jets cross sections at 13 TeV ATLAS-CONF-2016-046

jetsN

0≥ 1≥ 2≥ 3≥ 4≥ 5≥ 6≥ 7≥

) [p

b]je

ts*+

Nγ

(Z/

σ

-210

-110

1

10

210

310

410

510

610ATLAS Preliminary

1−13 TeV, 3.16 fb


< 2.5jet

y > 30 GeV, jet

Tp

) + jets−l+ l→*(γZ/

Data

HERPAS + ATHLACK B

2.1HERPA S

6YP + LPGEN A

8 CKKWLYP + MG5_aMC

8 FxFxYP + MG5_aMC

jetsN

0≥ 1≥ 2≥ 3≥ 4≥ 5≥ 6≥ 7≥

Pre

d./D

ata

0.5

1

1.5

jetsN

0≥ 1≥ 2≥ 3≥ 4≥ 5≥ 6≥ 7≥

Pre

d./D

ata

0.5

1

1.5

jetsN

0≥ 1≥ 2≥ 3≥ 4≥ 5≥ 6≥ 7≥

Pre

d./D

ata

0.5

1

1.5

[GeV]jet

Tp

50 100 150 200 250 300 350 400 450 500

[pb/

GeV

]je

t

T/d

pσd

-410

-310

-210

-110

1

10

210

310ATLAS Preliminary

1−13 TeV, 3.16 fb


< 2.5jet

y > 30 GeV, jet

Tp

) + 1 jet−l+ l→*(γZ/

Data

HERPAS + ATHLACK B

2.1HERPA S

6YP + LPGEN A

8 CKKWLYP + MG5_aMC

8 FxFxYP + MG5_aMC

[GeV]jet

Tp

50 100 150 200 250 300 350 400 450 500

Pre

d./D

ata

0.5

1

1.5

[GeV]jet

Tp

50 100 150 200 250 300 350 400 450 500P

red.

/Dat

a 0.5

1

1.5

[GeV]jet

Tp

50 100 150 200 250 300 350 400 450 500

Pre

d./D

ata

0.5

1

1.5


DPI in 4-jet events at 7 TeV (to JHEP) arXiv:1608.01857

cDPSξ

32 +

sDPSξ

31

0 0.2 0.4 0.6 0.8 1

sDP

Sξ

0

0.2

0.4

0.6

0.8

1

0

0.002

0.004

0.006

0.008

0.01

0.012simulation ATLAS

= 7 TeVs

SPS (AHJ) = 0.6R jets, tkAnti-

42.5 GeV≥ 1T

p

20 GeV≥ 2,3,4

Tp

4.4≤| 1,2,3,4

η|

cDPSξ

32 +

sDPSξ

31

0 0.2 0.4 0.6 0.8 1

sDP

Sξ

0

0.2

0.4

0.6

0.8

1

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

ATLAS

= 7 TeVs

cDPS (data, overlay) = 0.6R jets, tkAnti-

42.5 GeV≥ 1T

p

20 GeV≥ 2,3,4

Tp

4.4≤| 1,2,3,4

η|

cDPSξ

32 +

sDPSξ

31

0 0.2 0.4 0.6 0.8 1

sDP

Sξ

0

0.2

0.4

0.6

0.8

1

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.02

0.022 ATLAS

= 7 TeVs

sDPS (data, overlay) = 0.6R jets, tkAnti-

42.5 GeV≥ 1T

p

20 GeV≥ 2,3,4

Tp

4.4≤| 1,2,3,4

η|

[GeV]T

p

100 200 300 400

Ent

ries/

10 G

eV

1−10

1

10

210

310

410

510

610

710

ATLAS-1 = 7 TeV, 37 pbs

1T

p 2T

p3

Tp 4

Tp

Data 2010

= 0.6R jets, tkAnti-

42.5 GeV≥ 1T

p

20 GeV≥ 2,3,4

Tp

4.4≤| 1,2,3,4

η|

> Jets with anti-kt R = 0.6> pT > 20 GeV


Charged particle multiplicity in jets at 7 TeV EPJC 76(6) (2016) 1-23

> Jets with anti-kt R = 0.4> |η| < 2.1, pT > 50 GeV

trackn0 10 20 30

trac

kdn

dN

N1

0

0.1

0.2ATLAS

-1 = 20.3 fbint

= 8 TeV, Ls

< 100 GeVT

50 GeV < p

< 200 GeVT

100 GeV < p

< 1.2 TeVT

1 TeV < p

2012 Data

.175 CT10 AU2Pythia 8

2.63 CTEQ6L1 EE3Herwig++

> Tracks with |η| < 2.5> pT > 500 MeV

[GeV]T

Jet p0 500 1000 1500

Fra

ctio

ns

0

0.5

ATLAS Simulation = 8 TeVs

Pythia 8.175 CT10

forwardgluon - fractioncentral

gluonfractionforwardgluonfractioncentralgluonfraction


bb̄ cross section at 7 TeV arXiv:1607.08430

Definition Particle-level jets Detector-level jetsJet identification anti-kt with R = 0.4 anti-kt with R = 0.4

include muons and neutrinosb-jets definition b-hadron with pT > 5 GeV log10 (pb/pl) > 0.35

∆R (jet;b-hadron)¡0.3

Event selectionLeading jet pT > 270 GeV and |η| < 3.22 b-jets selection pT > 20 GeV and |η| < 2.5

2 b-jets separated by ∆R > 0.4

[rad]bb

φ∆

0.5 1 1.5 2 2.5 3

Rela

tive S

yste

matic U

ncert

ain

ty

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5Total Systematic Uncertainty

Jet Angular Resolution

b-Tagging �fficiency

Luminosity

Jet Energy Resolution

Jet Energy Scale

Template ✁it

Unfolding

ATLAS

g

g b

b

(a) flavour creation (s-channel)

g

g b

b

(b) flavour creation (t-channel)

g

g

g

b

b

(c) gluon splitting

g

g

g

b

b

(d) flavour excitation


Z/γ ϕ∗η at 13 TeV EPJC 76(5) (2016) 1-61

[GeV]llm60 80 100 120 140

Eve

nts

/ GeV

210

310

410

510

610

710

810

Data ee→Z

/eeµµ → γ γ WW, WZ, ZZ

multi-jet ν l →W

τ τ →Z + Single toptt

| < 2.4η > 20 GeV, |T

p

ATLAS -1=8 TeV, 20.3 fbs

ee-channel

[GeV]llT

p1 10 210

[%]

ll T/d

pσ

dσU

ncer

tain

ty o

n 1/

1−10

1

10Data statisticsDetectorBackground

ModelTotal systematic

ATLAS -1=8 TeV, 20.3 fbsee-channel

| < 2.4ll


Particle-level definitions (Treatment of final-state photon radiation)

electron pairs dressed; Bornmuon pairs bare; dressed; Borncombined Born

Fiducial regionLeptons pT > 20GeV and |η| < 2.4Lepton pairs |y``| < 2.4

Mass and rapidity regions46GeV < m`` < 66GeV |y``| < 0.8; 0.8 < |y``| < 1.6; 1.6 < |y``| < 2.4

(φ∗η measurements only)

|y``| < 2.4

66GeV < m`` < 116GeV |y``| < 0.4; 0.4 < |y``| < 0.8; 0.8 < |y``| < 1.2;1.2 < |y``| < 1.6; 1.6 < |y``| < 2.0; 2.0 < |y``| < 2.4;|y``| < 2.4

116GeV < m`` < 150GeV |y``| < 0.8; 0.8 < |y``| < 1.6; 1.6 < |y``| < 2.4(φ∗η measurements only)

|y``| < 2.4

Very-low mass regions12GeV < m`` < 20GeV }

|y``| < 2.4, p``T > 45GeV , p``T measurements only20GeV < m`` < 30GeV30GeV < m`` < 46GeV


W-boson angular distributions at 8 TeV arXiv:1609.07045E

ve

nts

/ 0

.1

50

100

150

200

250 1 = 8 TeV, 20.3 fbs

Data

0.71)× W+jets (ALPGEN

tt

MultijetsZ+jets

Diboson

> 500 GeVT

Leading Jet p

ATLAS

, closest jet)µR(∆

0 0.5 1 1.5 2 2.5 3 3.5 4

Data

/MC

0.5

1

1.5

Events

/ 0

.48

100

200

300

400

500

600

700

800 1 = 8 TeV, 20.3 fbs

Data

0.71)× W+jets (ALPGEN

tt

MultijetsZ+jets

Diboson

> 500 GeVT

Leading Jet p

ATLAS

jWφ∆

3 2 1 0 1 2 3

Da

ta/M

C

0.5

1

1.5

> At least one jet with pT > 500 GeV,exactly one muon, no b-tagged jetsand no electrons

Systematic Source 0.2 < ∆R < 2.4 ∆R > 2.4 InclusiveScaling of dijets to data 0.4% 0.1% 0.3%Scaling of tt̄ to data 0.6% 0.2% 0.5%Scaling of Z + jets to data 0.6% 0.3% 0.5%Jet energy scale 4.6% 5.8% 5.0%b-tagging efficiency 3.7% 1.2% 2.9%Data/MC disagreement for dijets 0.9% 0.6% 0.8%Data/MC disagreement for tt̄ 1.2% 0.4% 1.0%Data/MC disagreement for Z + jets 0.6% 1.5% 0.9%Diboson background estimate 2.2% 0.1% 1.5%Unfolding dependence on prior 1.1% 1.8% 1.3%Muon momentum scale and resolution 0.0% 0.1% 0.1%Muon reconstruction efficiency 0.4% 0.4% 0.4%Muon trigger efficiency 2.0% 1.9% 1.9%Jet energy resolution 0.6% 0.8% 0.6%MC background statistical 2.4% 1.8% 2.3%MC response statistical 1.7% 2.2% 1.9%Total systematic (excluding luminosity) 7.6% 7.4% 7.3%Luminosity 1.9% 2.0% 2.0%Data statistical 2.7% 3.6% 2.2%


WW cross section at 13 TeV ATLAS-CONF-2016-090

Selection requirement Selection value

p`T > 25 GeVη` |ηe| < 2.47 (excluding 1.37 < |ηe| < 1.52),

|ηµ| < 2.4Lepton identification Tight (electron), Medium (muon)Lepton isolation Gradient working pointNumber of additional leptons (pT > 10 GeV) 0meµ > 10 GeVNumber of jets with pT >25(30) GeV, |η| <2.5(4.5) 0Number of b-tagged jets ( pT > 20 GeV, 85% op. point) 0Emiss

T, Rel > 15 GeV

pmissT > 20 GeV

Sources of uncertainty Relative uncertainty for σfidWW→eµ

Jet selection and energy scale & resolution 7.3%b-tagging 1.3%Emiss

T and pmissT 1.7%

Electron 1.0%Muon 0.4%Pile-up 0.9%Luminosity 2.1%Top-quark background theory 2.4%Drell–Yan background theory 1.5%W+jet and multijet background 3.8%Other dibosons background 1.1%Parton-shower 3.1 %PDF 0.2 %QCD scale 0.2%MC statistics 1.2 %Data statistics 3.7%

Total uncertainty 11%

Events

/ 1

3 G

eV

50

100

150

200

250

300

350

400

Data stat)⊕ SM (sys

WW Top Quark DrellYan W+jets Diboson


, SRν

±

µν±e→WW

[GeV]µe

Tp

0 20 40 60 80 100 120 140 160 180 200

Da

ta /

SM

0.6

0.8

1

1.2

1.4

Cross section ratio (13 TeV / 8 TeV)

0.8 1 1.2 1.4 1.6 1.8 2 2.2

Data

stat.

stat.+syst.

nNNLO+H Prediction

ν

±

µν± e→WW

(8 TeV)1 (13 TeV) and 20.3 fb13.16 fb

Total cross section ratio(13 TeV / 8 TeV)

Fiducial cross section ratio(13 TeV / 8 TeV)

ATLAS Preliminary


WZ cross sections at 13 TeV PLB 762 (2016) 1; ATLAS-CONF-2016-043E

vents

/ 1

0 G

eV

50

100

150

200

250

300

350Data

Z (corr. to NNLO)±WMisid. leptons

ZZtt+V

OthersTot. unc.

ℓ′ℓℓ

ℓ′, ℓ )µ( = e or


[GeV]Z

Tp

0 100 200 300 400

Da

ta /

MC

0

1

2

[f

b]

Z T p

∆ /

fid.

σ∆

1−10

Data

Powheg+Pythia

Sherpa

ATLAS Preliminary

1 = 13 TeV, 13.3 fbs

ν →Z ±W ℓ′ ℓℓ

[fb

]fid

σ∆

10

[GeV]Z

Tp

0 100 200

Ratio to P

ow

heg

0.6

0.8

1

1.2

1.4

∞

eee µee eµµ µµµ combinedRelative uncertainties [%]

e energy scale 0.3 0.2 0.2 0.0 0.1e id. efficiency 4.6 2.7 1.9 0.0 1.3µ momentum scale 0.0 0.1 0.1 0.2 0.1µ id. efficiency 0.0 1.3 2.6 3.7 2.6Emiss

T and jets 0.5 0.4 0.8 0.9 0.8Trigger 0.1 0.1 0.1 0.2 0.1Pileup 0.5 1.2 1.4 1.1 1.1Misid. leptons background 11.9 5.6 11.9 1.7 3.1ZZ background 0.6 0.7 0.6 0.6 0.6Other Irr. backgrounds 0.5 0.5 0.4 0.3 0.4Uncorrelated 10.6 9.2 6.2 3.6 2.9Total systematics 16.6 11.3 13.9 5.7 5.5Luminosity 3.3 3.3 3.2 3.2 3.2Statistics 6.2 5.3 5.3 4.1 2.7Total 18.1 12.9 15.2 7.7 6.9


ZZ cross section at 13 TeV PRL 116, 101801 (2016)

Z candidate mass [GeV]T,ll

pSubleading-20 40 60 80 100 120 140 160 180

Z c

andi

date

mas

s [G

eV]

T,ll

pLe

adin

g-

20

40

60

80

100

120

140

160

180

Data 4l→ZZ


-0.11

+1.08Expected background: 0.62

[GeV]4lm Mass of four-lepton system 200 300 400 500 600 700

Eve

nts

/ 20

GeV

0

2

4

6

8

10

12

14

16

18

Data

4l→ZZ→qq 4l→ZZ→gg

Prediction uncertainty


-0.11

+1.08Expected background: 0.62


Zγ and Zγγ production at 8 TeV PRD 93, 112002 (2016)

[GeV]γγm0 50 100 150 200 250 300 350

Eve

nts

/ 20

GeV

0

2

4

6

8

10

12

14

16

18 Data

γγZ(ee)

,jjγj,jγZ+

Other BKG

syst.⊕stat.


γ3h

0.005− 0 0.005

γ 4h

0.06−

0.04−

0.02−

0

0.02

0.04

0.06

3−10×

-1=8 TeV, 20.3 fbs

γνν → and pp γ-l+ l→pp

= 4 TeVFFΛ

ATLAS

Observed 95% C.L. contour

Expected 95% C.L. contour

Observed best-fit value

Cuts `+`−γ `+`−γγ νν̄γ νν̄γγLepton p`T > 25 GeV p`T > 25 GeV - -

|η`| < 2.47 |η`| < 2.47 - -Boson m`+`− > 40 GeV m`+`− > 40 GeV pνν̄T > 100 GeV pνν̄T > 110 GeVPhoton EγT > 15 GeV EγT > 15 GeV EγT > 130 GeV EγT > 22 GeV

|ηγ | < 2.37∆R(`, γ) > 0.7 ∆R(`, γ) > 0.4 - -

- ∆R(γ, γ) > 0.4 - ∆R(γ, γ) > 0.4εph <0.5

Jet pjetT > 30 GeV, |ηjet| < 4.5

∆R(jet, `/γ) > 0.3 ∆R(jet, `/γ) > 0.3 ∆R(jet, γ) > 0.3 ∆R(jet, γ) > 0.3Inclusive : Njet ≥ 0, Exclusive : Njet = 0

Coupling strength-3 10×

15− 10− 5− 0 5 10 15

-1=8 TeV, 20.3 fbs, γνν and γATLAS, ll-1=8 TeV, 19.6 fbs, γννCMS,

-1=7 TeV, 5.0 fbs, γνν and γCMS, ll-1=8 TeV, 19.5 fbs, γCMS, ll

-1=7 TeV, 4.6 fbs, γνν and γATLAS, ll

Z3h

γ3h

∞ = FFΛ95% C.L., ATLAS


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Overview of SM/QCD Physics at ATLAS