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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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
2 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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.
3 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
12 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
CMS Preliminary = 8 TeVs
-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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
14 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
15 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
17 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
WIMP-NUCLEON SCATTERING LIMITS
[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.
18 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
WIMP-NUCLEON SCATTERING LIMITS
[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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
23 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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.
24 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
Auxiliary slides
25 / 28
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
WIMP-NUCLEON SCATTERING LIMITS
[ 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(→qD5: 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
Dirac)χχ j(→qD8: q
Dirac)χχ j(→qD9: 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
INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
WIMP-NUCLEON SCATTERING LIMITS
]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
CMS Preliminary = 8 TeVs
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
CMS Preliminary = 8 TeVs
-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