JamesDPearce_MonoX

INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY

“Dark matter searches” with a focus on newtechniques (Mono-X)

WIN2013: Natal, Brazil

James D Pearce,On behalf of the ATLAS and CMS collaborations

Sept 16, 2013

1 / 28


OUTLINE

1. Dark Matter BackgroundI Evidence for Dark MatterI The “WIMP Miracle”

2. Effective Field Theories3. Detection Methods4. Mono-X Analyses

I Monojet (ATLAS)I Monophoton (CMS)I Mono-W/Z (ATLAS + CMS)I Mono-b

5. Summary6. Auxiliary Material

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EVIDENCE FOR DARK MATTER (I)Galactic Rotation Curves Strong Gravitational Lensing

I Galactic rotation curves showstars orbit at the same speeds

I This implies mass density ofgalaxies is uniform.

I Image of Abell 1689 cluster asobserved by the hubbletelescope

I The mass of galaxies is notenough to account for thestrong gravitational lensing.

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EVIDENCE FOR DARK MATTER (II)Weak Gravitational Lensing Cosmic Microwave Background

I Two galaxy clusters colliding.I The pink shows the x-ray

emissions.I Blue shows unseen mass as

measured with weakgravitational lensingtechniques.

I Anisotropies in the CMB aredue to acoustic oscillations inthe early universe.

I Angular scales of theoscillations reveal the differenteffects of baryonic matter andDM. 4 / 28


RELIC ABUNDANCE AND THE “WIMP MIRACLE”

1. DM and SM particles are inthermal (chemical) equilibrium.

2. Universe expands and cools;DM production dropsexponentially (∼ e−mχ/T).

3. Energy drops below DMproduction threshold; DMabundance remains constant(“Freeze out”).

We are left with a relic abundance ofDM:

Ωχ ∝ 1〈σv〉 ∼

m2χ

gχ4

5 / 28


WHAT WE KNOW ABOUT DARK MATTER

1. It’s neutral under electric charge, since it does not produce photons,2. It’s stable, or at least has a lifetime on cosmological scales,3. It’s non-baryonic, to preserve the success of ΛCDM,4. It has a relic abundance consistent with weak scale mass and

interactions.

These seem to all point us to some sort of weakly interacting massiveparticle (WIMP). We can use an EFT to model what we know about DM,without resorting to any one specific UV complete theory (eg. SUSY,LED, etc.)

6 / 28


FROM UV COMPLETE TO EFT (I)

UV complete Theory Effective Theory

By Taylor expanding the SM-DM propagator around the momentumtransfer and only keeping the leading order we get an effective couplingconstant:

1Q2

tr−M2 = − 1M2

(1 +

Q2tr

M2 +O(

Q4tr

M4

))≈ − 1

M2

This approximation is only valid if Q2tr M2 otherwise all other terms in

the expansion (UV complete theory) must be considered.7 / 28


FROM UV COMPLETE TO EFT (II)

Once the mediator has been “integrated out” we no longer talk about theparameter M, instead we replace it with M∗, which parameterizes theenergy scale of the EFT. M∗ is the most important parameter of thetheory, it’s related to the mediator mass and couplings, and tells uswhere the EFT approach breaks down:

I M∗ = M/√gχgq, where gχ and gq are the couplings of the mediator

to the DM and quark fields.I 4-momentum conservation requires mχ < M/2I Perturbation theory requires gχgq < (4π)2

I Therefore our EFT is valid for mχ < 2πM∗

This EFT language allows us to relate different experimental signaturesin a model-independent way. As we’ll see the relic abundance, directdetection signal, and collider predictions depend only on M∗.

8 / 28


FROM UV COMPLETE TO EFT (III)

Name Operator CoefficientD1 χχqq mq/M3

∗D2 χγ5χqq imq/M3

∗D3 χχqγ5q imq/M3

∗D4 χγ5χqγ5q mq/M3

∗D5 χγµχqγµq 1/M2

∗D6 χγµγ5χqγµq 1/M2

∗D7 χγµχqγµγ5q 1/M2

∗D8 χγµγ5χqγµγ5q 1/M2

∗D9 χσµνχqσµνq 1/M2

∗D10 χσµνγ

5χqσαβq i/M2∗

D11 χχGµνGµν αs/4M3∗

D12 χγ5χGµνGµν iαs/4M3∗

D13 χχGµνGµν iαs/4M3∗

D14 χγ5χGµνGµν αs/4M3∗

arXiv:1008.1783

I The theory is thencharacterized by an effectiveLagrangian Leff :

Leff =∑

ciOi

Where ci ∼ 1M∗d−4 and Oi is an

effective operator which issome Lorentz invariantcombination of the SM andDM (χ) fields.

I Place limits on arepresentative set: D1 (scalar),D5 (vector), D8 (axial-vector),D9 (tensor) and D11 (couplesto gluons)

9 / 28

http://arxiv.org/abs/1008.1783


DETECTION METHODSCollider Direct detection Indirect detection

Experiments:I ATLASI CMSI D0I CDF

Experiments:I XENON100I CDMSI SIMPLEI CoGentI IceCubeI PicassoI COUPP

Experiments:I Fermi-LATI PAMELAI AMS-02I WMAPI Planck

...and many more10 / 28


MONOJET ANALYSIS (ATLAS/CMS)

Main Backgrounds:I Z(→ νν)+ jet(s) (50-70%)I W(→ linvν) + jet(s) (46-29%)I Z(→ linvlinv) + jet(s) (4-0%)

EW background estimate (ATLAS):

I NestSR = (NData

CR −NbkgCR )×(1−FEW)×TF

I where 1− FEW =NMC

CRAll EW∑

NMCCR

I and TF =NMC

SRNMC

CR

MC EW background estimate (CMS):I Z+ jets, W+ jets, tt and single top:I MadGraph→ Phythia6: Z2Star tune

with CTEQ6L1 pdf

CMS-PAS-EXO-12-048 ATLAS-CONF-2012-14711 / 28

http://cds.cern.ch/record/1525585?ln=en

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2012-147/


MONOJET ANALYSIS (CMS)

[GeV] TmissE

200 300 400 500 600 700 800 900 1000

Eve

nts

/ 25

GeV

1

10

210

310

410

510

610

710 νν→Z

νl→W

tt

t

QCD-l+l→Z

= 3δ= 2 TeV, DADD M

= 1 GeVχ = 892 GeV, MΛDM

= 2 TeVUΛ=1.7, U

Unparticles d

Data

CMS Preliminary = 8 TeVs

-1L dt = 19.5 fb∫

[GeV] TmissE

200 300 400 500 600 700 800 900 1000

Dat

a / M

C

0

0.5

1

1.5

2

SelectionI Trigger: Emiss

T > 80 GeVI Lead jet: pT > 110 GeV,|η| < 2.4

I lepton veto: e, µ, τI ∆φ(jet1, jet2) < 2.5I jet veto: Njet ≤ 2I Scan in Emiss

T

Blue dashed line indicateshypothetical DM signal

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ENERGY SCALE LIMITS

[GeV]WIMP mass m210 310

[GeV

]*

Supp

ress

ion

scal

e M

100

150

200

250

300

350

400

450

500 , SR3, 90%CL Operator D11)exp 2± 1 ±Expected limit (

)theory 1±Observed limit (

Thermal relic

PreliminaryATLAS

=8 TeVs-1Ldt = 10.5 fb

not valideffective theory

]2 [GeV/cχM1 10 210 310

[GeV

]Λ

300

1000

CMS 2012 Vector

CMS 2011 Vector


-1L dt = 19.5 fb∫

I Green line indicates the M∗ values at which WIMPs of a given masswould result in the required relic abundance.

I M∗ limits above the thermal relic line means exclusion or negativeinterference or additional annihilation (e.g. to leptons)

I The light-grey region indicates where the EFT breaks down.13 / 28


WIMP-NUCLEON SCATTERING LIMITS

]2 [GeV/cχM1 10 210 310

]2-N

ucle

on C

ross

Sec

tion

[cm

χ

-4610

-4510

-4410

-4310

-4210

-4110

-4010

-3910

-3810

-3710

-3610

-1 = 8 TeV, 19.5 fbsCMS,

-1 = 7 TeV, 5.1 fbsCMS,

XENON100

COUPP 2012

SIMPLE 2012CoGeNT 2011

CDMS II

CMS Preliminary

2Λ

q)µγq)(χµ

γχ(Spin Independent, Vector Operator

]2 [GeV/cχM1 10 210 310

]2-N

ucle

on C

ross

Sec

tion

[cm

χ-4610

-4510

-4410

-4310

-4210

-4110

-4010

-3910

-3810

-3710

-3610

-1 = 8 TeV, 19.5 fbsCMS,

-1 = 7 TeV, 5.1 fbsCMS,

COUPP 2012

-W+

IceCube W

SIMPLE 2012

-W+

Super-K W

CMS Preliminary

2Λ

q)5

γµγq)(χ5

γµ

γχ(Spin Dependent, Axial-vector operator

I Cross sections above observed are excluded.I Assumption is that DM interacts with SM particles solely by a given

operator: SI = D5, SD = D8I Yellow contours show candidate events from CDMS: arXiv:1304.4279

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http://arxiv.org/abs/1304.4279


WIMP ANNIHILATION LIMITS

[ GeV ]WIMP mass m1 10 210 310

/ s]

3 q

q [c

m

v> fo

r An

nihi

latio

n ra

te <

-2910

-2810

-2710

-2610

-2510

-2410

-2310

-2210

-2110

-2010

-1910

Thermal relic value

)b bMajorana

) ( Fermi-LAT dSphs (×2

Dirac) (qD5: q

Dirac) (qD8: q

theory-1

ATLAS , 95%CL-1 = 7 TeV, 4.7 fbs

I Comparison with FERMI-LATis possible through our EFT

I The results can also beinterpreted in terms of limitson WIMPs annihilating tolight quarks

I All limits shown here assume100% branching fractions ofWIMPs annihilating to quarks

I Below 10 GeV for D5 and 70GeV for D8 the ATLAS limitsare below the values neededfor WIMPs to make up theDM relic abundance

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MONOPHOTON ANALYSIS (CMS)

Main Backgrounds:I Zγ → νν + γ (60%)I Wγ → linvν + γ, di-γ andγ+ jet (5%)

I Fake photons (20%)

Background EstimatesI All backgrounds estimated with

MCI Z/γ(NLO), di-γ and γ+ jet←

Pythia6 with CTEQ6L1I Wγ(NLO)←MadGraph5

CMS-EXO-11-096 CERN-PH-EP-2012-209 16 / 28




MONOPHOTON ANALYSIS

[GeV]TE200 300 400 500 600 700

Eve

nts

/GeV

-410

-310

-210

-110

1

10

[GeV]TE200 300 400 500 600 700

Eve

nts

/GeV

-410

-310

-210

-110

1

10 = 7 TeVsCMS,

-1 5.0 fb

DATA Total uncertainty on Bkg

γνν →γ Zν e→W

(QCD)γMisID-γ+jets, Wγ

Beam Halo=1 TeV, n=3)

DSM+ADD(M

Selection:I Trigger: Single photonI Photon: pT > 145 GeV,|η| < 1.44 (barrel region)

I Energy ratio: HCAL/ECAL< 0.05 within ∆R < 0.15

I Lepton veto and hadronicactivity veto

I Isolated photonsI jet veto: Njet ≤ 2I SR: Emiss

T > 130 GeV, |η| < 4.5

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[GeV]χ M1 10 210 310

]2-N

ucle

on C

ross

Sec

tion

[cm

χ

-4510

-4310

-4110

-3910

-3710

-3510

Spin IndependentCMS (90%CL)CDFXENON100

CDMS II 2011CDMS II 2010CoGeNT 2011

= 7 TeVsCMS,

-15.0 fb

(a)

[GeV]χ M1 10 210 310

]2-N

ucle

on C

ross

Sec

tion

[cm

χ

-4510

-4310

-4110

-3910

-3710

-3510

Spin Dependent

CMS (90%CL)

CDF

SIMPLE 2010

COUPP 2011)-W+W→χχIceCube (

)-W+W→χχSuper-K I+II+III (

= 7 TeVsCMS, -15.0 fb

(b)

I Cross sections above observed are excluded.I Spin-dependent/independent limits correspond to D8 and D5

operators.I Not sensitive to D11 (gluon) operator.

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MONO-W/Z ANALYSES (ATLAS/CMS)

Two possible diagrams lead tointerference:

1. ξ = −1: signal enhancedI leads to stronger signal

than monojet!

2. ξ = +1: signal suppressed

Two different strategies:1. ATLAS: look for a single fat-jet

with internal structure(mono-W/Z)

I Same backgrounds as monojetanalysis

I Similar data-drivenbackground estimate

2. CMS: look for single lepton(mono-W)

I W → lν, tt, single top,Drell-Yan, diboson

I Background estimated fromMC

CMS-EXO-12-060 ATLAS-CONF-2013-07319 / 28

https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsEXO12060

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2013-073/


MONO-W/Z A.K.A. MONO-FATJET (ATLAS)

[GeV] jetm

50 60 70 80 90 100 110 120

Events

/ 1

0G

eV

0

5

10

15

20

25

30

35

40

45Data

)+jetννZ(

)+jetτ/µW/Z(e/

Top

Diboson

uncertainty

D5(u=d) x20

D5(u=d) x0.2

ATLAS Preliminary

= 8 TeVs 1

L dt = 20.3 fb∫

> 500 GeVmiss

TSR: E

Selection:I Trigger: Emiss

T > 80 GeVI Fat jet: Cambridge-Aachen

algorithm, R = 1.2, first twosub-jets balanced (√y > 0.4),pT > 250 GeV, |η| < 1.2,mjet = 50− 120 GeV

I Veto leptons (e, µ) and photonsI tt supression: veto if>= 2 AntiKt4 jets with∆R(jetFat, jetAntiKt4) > 0.9 OR∆φ(Emiss

T , jet) < 0.4 for anyAntiKt4 jets.

I SR: EmissT > 350, 500 GeV

20 / 28


MONO-W A.K.A. MONO-LEPTON (CMS)

(GeV)TM500 1000 1500 2000 2500

Eve

nts

/ 1

GeV

-410

-310

-210

-110

1

10

210

310

410

510

610Spin Independent

= 200 GeVΛ = 300 GeV χM ν l →W +single toptt

DY QCD

Diboson data

syst uncer.

= +1ξDM

= -1ξDM

= 0ξDM

CMS Preliminary -1 L dt = 20 fb∫ miss

T + Eµ = 8 TeVs

Selection:I Trigger: single muon (pT > 40

GeV) or electron (pT > 80 GeV)triggers

I Muons: pT > 45 (offline) GeV,|η| < 2.1, isolated

I Electrons: pT > 100 (offline)GeV, |η| < 1.442 or1.566 < |η| < 2.5, isolated

I Back-to-back kinematics:0.4 < pT/Emiss

T < 1.5 AND∆φ(Emiss

T , l) > 0.8πI SR: mT > 1, 1.5, 2 TeV

21 / 28



[GeV]χm1 10

2103

10

]2

N c

rosss

ectio

n [

cm

χ

4610

4410

4210

4010

3810

3610D5(u=d):obs D5(u=d):obs

CoGeNT 2010 CDMS lowenergy

XENON100 2012 )χχD5:ATLAS 7TeV j(

ATLAS Preliminary = 8 TeVs 1

L dt = 20.3 fb∫

90% CL

spin independent

(GeV)χM1 10 210 310

)2 (

cmσ

-pro

ton

χ

-4110

-4010

-3910

-3810

-3710

-3610

-3510=-1 ξExpected limit for

=0 ξExpected limit for

=+1 ξExpected limit for

=-1 ξObserved limit for

=0 ξObserved limit for

=+1 ξObserved limit for

= 8 TeVs -1CMS Preliminary 2012 20 fb

Spin Independent

I Cross sections above observed are excluded.I Assuming constructive interference gives better limits then ATLAS

monojet and monophoton combined!I Not sensitive to D11 (gluon) operator.

22 / 28


MONO-b

b

g b

X

X

Motivation:I D1 is proportional to the initial

quark mass (D1 ∼ mq

M3∗

)

I By approximate QCD flavoursymmetry the outgoing quarkwill be a b

I Analysis for 2012 data iscurrently underway (ATLAS)

I Despite the kinematic and PDFsuppression for producing thirdgeneration quarksimprovement on limits is up to3 orders of magnitude!

100 101 102 103

mX [GeV]

10−46

10−45

10−44

10−43

10−42

10−41

10−40

10−39

10−38

10−37

10−36

10−35

σn

[cm

2]

ATLAS 7 TeV, 4.7 fb−1

XENON 100

Limits from mono-b search

14 TeV, 300 fb−1, pileup 50

14 TeV, 3000 fb−1, pileup 140

33 TeV, 3000 fb−1, pileup 140

arXiv:1307.7834

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http://arxiv.org/abs/arXiv:1307.7834


SUMMARY

I WIMPs are well motivated by what we know about Dark Matter andthe observed relic abundance.

I EFT’s allow us to search for WIMPs in a model-independent way aswell as compare results from different experiments and signatures.

I Mono-X searches at the LHC are competitive and complementary todirect and indirect detection experiments.

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Auxiliary slides

25 / 28


MONOJET ANALYSIS(ATLAS)

[Eve

nts/

GeV

]Tm

iss

dN/d

E

-110

1

10

210

310

410

510 data 2012Total BG

) + jets Z ( ) + jets l W (

Multi-jetNon-collision BG

ll ) + jetsZ ( Dibosons

+ single toptt=3 TeV (x5)DADD n=2, M

=670GeV (x5)*

D5 M=80GeV, MeV (x5)-4=10

G~=1TeV, M

g~/q~, Mg~/q~ + G~

-1 Ldt=10.5fb

= 8 TeVs

ATLAS Preliminary

[E

vent

s/G

eV]

Tmis

sdN

/dE

-110

1

10

210

310

410

510

[GeV]TmissE

200 400 600 800 1000 1200

Dat

a / B

G

0.51

1.5

I Orange dashed line indicateshypothetical DM signal (×5)

Selection:I Trigger: Emiss

T > 80 GeVI At least one primary vetexI Lead jet: pT > 120 GeV, |η| < 2I lepton veto: e, µI Multijet suppression:

∆φ(EmissT , jet2) > 0.5

I jet veto: Njet ≤ 2I SR:

EmissT > 120, 220, 350, 500 GeV

jet pT > 120, 220, 350, 500 GeV

26 / 28



[ GeV ]χ

WIMP mass m

1 10210

310

]2

WIM

PN

ucle

on c

ross s

ection [ c

m

4510

4310

4110

3910

3710

3510

3310

3110

2910ATLAS , 90%CL1 = 7 TeV, 4.7 fbs

Spinindependent

XENON100 2012

CDMSII lowenergy

CoGeNT 2010

Dirac)χχ j(→qD5: CDF q

Dirac)χχ j(→qD1: q


Dirac)χχ j(→D11: gg

theoryσ1

[ GeV ]χ

WIMP mass m

1 10210

310

]2

WIM

Pn

ucle

on c

ross s

ection [ c

m

4110

4010

3910

3810

3710

3610

3510

ATLAS , 90%CL1 = 7 TeV, 4.7 fbs

Spindependent

SIMPLE 2011

Picasso 2012

Dirac)χχ j(→qD8: CDF q

Dirac)χχ j(→qD8: CMS q



theoryσ1

I Cross sections above observed are excluded.I Assumption is that DM interacts with SM particles solely by a given

operator

arXiv:1210.4491

27 / 28

http://arxiv.org/abs/arXiv:1210.4491



]2 [GeV/cχM1 10 210 310

]2-N

ucle

on C

ross

Sec

tion

[cm

χ

-4610

-4410

-4210

-4010

-3810

-3610

-3410

-3210

-3010

-2810-2710

CMS 2012 VectorCMS 2011 VectorCDF 2012XENON100 2012 COUPP 2012 SIMPLE 2012 CoGeNT 2011CDMSII 2011 CDMSII 2010


Spin Independent

-1L dt = 19.5 fb∫

2Λ

q)µγq)(χµ

γχ(

]2Mediator Mass M [TeV/c-110 1 10

[GeV

]Λ

90%

CL

limit

on

0

500

1000

1500

2000

2500

3000=M/3Γ, 2=500 GeV/cχm

=M/10Γ, 2=500 GeV/cχm

π=M/8Γ, 2=500 GeV/cχm

=M/3Γ, 2=50 GeV/cχm

=M/10Γ, 2=50 GeV/cχm

π=M/8Γ, 2=50 GeV/cχm


-1L dt = 19.5 fb∫

2Λ

q)µγq)(χµγχ(

I CMS (2012) limits for D5 (vector) operatorI Light mediator model is studied to see how limits change with

mediator mass, WIMP mass and decay width.

CMS-PAS-EXO-12-048

28 / 28


JamesDPearce_MonoX

Documents

new techniques monox

detection methods

expansion uv complete

specic uv complete theory

weak scale mass

mass of galaxies

relic abundance consistent

wimp miracle