JamesDPearce_MonoX

INTRO BACKGROUND EFT’S DETECTION MONOJET MONOPHOTON MONO-W/Z MONO-b SUMMARY
“Dark matter searches” with a focus on new
techniques (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 Background
Evidence for Dark Matter
The “WIMP Miracle”
2. Effective Field Theories
3. Detection Methods
4. Mono-X Analyses
Monojet (ATLAS)
Monophoton (CMS)
Mono-W/Z (ATLAS + CMS)
Mono-b
5. Summary
6. Auxiliary Material
2 / 28

EVIDENCE FOR DARK MATTER (I)
Galactic Rotation Curves Strong Gravitational Lensing
Galactic rotation curves show
stars orbit at the same speeds
This implies mass density of
galaxies is uniform.
Image of Abell 1689 cluster as
observed by the hubble
telescope
The mass of galaxies is not
enough to account for the
strong gravitational lensing.
3 / 28

EVIDENCE FOR DARK MATTER (II)
Weak Gravitational Lensing Cosmic Microwave Background
Two galaxy clusters colliding.
The pink shows the x-ray
emissions.
Blue shows unseen mass as
measured with weak
gravitational lensing
techniques.
Anisotropies in the CMB are
due to acoustic oscillations in
the early universe.
Angular scales of the
oscillations reveal the different
effects of baryonic matter and
DM. 4 / 28

RELIC ABUNDANCE AND THE “WIMP MIRACLE”
1. DM and SM particles are in
thermal (chemical) equilibrium.
2. Universe expands and cools;
DM production drops
exponentially (∼ e−mχ/T).
3. Energy drops below DM
production threshold; DM
abundance remains constant
(“Freeze out”).
We are left with a relic abundance of
DM:
Ωχ ∝ 1
σv ∼
m2
χ
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 massive
particle (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 momentum
transfer and only keeping the leading order we get an effective coupling
constant:
1
Q2
tr−M2 = − 1
M2 1 +
Q2
tr
M2 + O
Q4
tr
M4 ≈ − 1
M2
This approximation is only valid if Q2
tr 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 the
parameter M, instead we replace it with M∗, which parameterizes the
energy scale of the EFT. M∗ is the most important parameter of the
theory, it’s related to the mediator mass and couplings, and tells us
where the EFT approach breaks down:
M∗ = M/
√
gχgq, where gχ and gq are the couplings of the mediator
to the DM and quark ﬁelds.
4-momentum conservation requires mχ < M/2
Perturbation theory requires gχgq < (4π)2
Therefore our EFT is valid for mχ < 2πM∗
This EFT language allows us to relate different experimental signatures
in a model-independent way. As we’ll see the relic abundance, direct
detection signal, and collider predictions depend only on M∗.
8 / 28

FROM UV COMPLETE TO EFT (III)
Name Operator Coefﬁcient
D1 ¯χχ¯qq mq/M3
∗
D2 ¯χγ5χ¯qq imq/M3
∗
D3 ¯χχ¯qγ5q imq/M3
∗
D4 ¯χγ5χ¯qγ5q mq/M3
∗
D5 ¯χγµχ¯qγµq 1/M2
∗
D6 ¯χγµγ5χ¯qγµq 1/M2
∗
D7 ¯χγµχ¯qγµγ5q 1/M2
∗
D8 ¯χγµγ5χ¯qγµγ5q 1/M2
∗
D9 ¯χσµνχ¯qσµνq 1/M2
∗
D10 ¯χσµνγ5χ¯qσαβq i/M2
∗
D11 ¯χχGµνGµν αs/4M3
∗
D12 ¯χγ5χGµνGµν iαs/4M3
∗
D13 ¯χχGµν
˜Gµν iαs/4M3
∗
D14 ¯χγ5χGµν
˜Gµν αs/4M3
∗
arXiv:1008.1783
The theory is then
characterized by an effective
Lagrangian Leff :
Leff = ciOi
Where ci ∼ 1
M∗
d−4 and Oi is an
effective operator which is
some Lorentz invariant
combination of the SM and
DM (χ) ﬁelds.
Place limits on a
representative set: D1 (scalar),
D5 (vector), D8 (axial-vector),
D9 (tensor) and D11 (couples
to gluons)
9 / 28

DETECTION METHODS
Collider Direct detection Indirect detection
Experiments:
ATLAS
CMS
D0
CDF
Experiments:
XENON100
CDMS
SIMPLE
CoGent
IceCube
Picasso
COUPP
Experiments:
Fermi-LAT
PAMELA
AMS-02
WMAP
Planck
...and many more
10 / 28

MONOJET ANALYSIS (ATLAS/CMS)
Main Backgrounds:
Z(→ νν)+ jet(s) (50-70%)
W(→ linvν) + jet(s) (46-29%)
Z(→ linvlinv) + jet(s) (4-0%)
EW background estimate (ATLAS):
Nest
SR = (NData
CR −N
bkg
CR )×(1−FEW)×TF
where 1 − FEW =
NMC
CR
All EW
NMC
CR
and TF =
NMC
SR
NMC
CR
MC EW background estimate (CMS):
Z+ jets, W+ jets, t¯t and single top:
MadGraph → Phythia6: Z2Star tune
with CTEQ6L1 pdf
CMS-PAS-EXO-12-048 ATLAS-CONF-2012-147
11 / 28

MONOJET ANALYSIS (CMS)
[GeV]T
miss
E
200 300 400 500 600 700 800 900 1000
Events/25GeV
1
10
2
10
3
10
4
10
5
10
6
10
7
10 νν→Z
νl→W
tt
t
QCD
-
l
+
l→Z
= 3δ= 2 TeV,D
ADD M
= 1 GeVχ
= 892 GeV, MΛDM
= 2 TeVU
Λ=1.7,
U
Unparticles d
Data
CMS Preliminary
= 8 TeVs
-1
L dt = 19.5 fb∫
[GeV]T
miss
E
200 300 400 500 600 700 800 900 1000
Data/MC
0
0.5
1
1.5
2
Selection
Trigger: Emiss
T > 80 GeV
Lead jet: pT > 110 GeV,
|η| < 2.4
lepton veto: e, µ, τ
∆φ(jet1, jet2) < 2.5
jet veto: Njet ≤ 2
Scan in Emiss
T
Blue dashed line indicates
hypothetical DM signal
12 / 28

ENERGY SCALE LIMITS
[GeV]WIMP mass m
2
10
3
10
[GeV]
*
SuppressionscaleM
100
150
200
250
300
350
400
450
500 , SR3, 90%CLOperator D11
)exp
2±1±Expected limit (
)theory
1±Observed limit (
Thermal relic
PreliminaryATLAS
=8 TeVs
-1
Ldt = 10.5 fb
not valid
effective theory
]2
[GeV/cχM
1 10
2
10
3
10
[GeV]Λ
300
1000
CMS 2012 Vector
CMS 2011 Vector
CMS Preliminary
= 8 TeVs
-1
L dt = 19.5 fb∫
Green line indicates the M∗ values at which WIMPs of a given mass
would result in the required relic abundance.
M∗ limits above the thermal relic line means exclusion or negative
interference or additional annihilation (e.g. to leptons)
The light-grey region indicates where the EFT breaks down.
13 / 28

WIMP-NUCLEON SCATTERING LIMITS
]2
[GeV/cχM
1 10
2
10
3
10
]2
-NucleonCrossSection[cmχ
-46
10
-45
10
-44
10
-43
10
-42
10
-41
10
-40
10
-39
10
-38
10
-37
10
-36
10
-1
= 8 TeV, 19.5 fbsCMS,
-1
XENON100
COUPP 2012
SIMPLE 2012
CoGeNT 2011
CDMS II
CMS Preliminary
2
Λ
q)µ
γq)(χµ
γχ(
Spin Independent, Vector Operator
]2
[GeV/cχM
1 10
2
10
3
10
]2
-46
10
-45
10
-44
10
-43
10
-42
10
-41
10
-40
10
-39
10
-38
10
-37
10
-36
10
-1
-1
COUPP 2012
-
W+
IceCube W
SIMPLE 2012
-
W+
Super-K W
CMS Preliminary
2
Λ
q)
5
γµ
γq)(χ
5
γµ
γχ(
Spin Dependent, Axial-vector operator
Cross sections above observed are excluded.
Assumption is that DM interacts with SM particles solely by a given
operator: SI = D5, SD = D8
Yellow contours show candidate events from CDMS: arXiv:1304.4279
14 / 28

WIMP ANNIHILATION LIMITS
[ GeV ]WIMP mass m
1 10 2
10 3
10
/s]3
qq[cmv>forAnnihilationrate<
-29
10
-28
10
-27
10
-26
10
-25
10
-24
10
-23
10
-22
10
-21
10
-20
10
-19
10
Thermal relic value
)bb
Majorana
)( Fermi-LAT dSphs (×2
Dirac
)(qD5: q
Dirac
)(qD8: q
theory
-1
ATLAS , 95%CL-1
= 7 TeV, 4.7 fbs
Comparison with FERMI-LAT
is possible through our EFT
The results can also be
interpreted in terms of limits
on WIMPs annihilating to
light quarks
All limits shown here assume
100% branching fractions of
WIMPs annihilating to quarks
Below 10 GeV for D5 and 70
GeV for D8 the ATLAS limits
are below the values needed
for WIMPs to make up the
DM relic abundance
15 / 28

MONOPHOTON ANALYSIS (CMS)
Main Backgrounds:
Zγ → νν + γ (60%)
Wγ → linvν + γ, di-γ and
γ+ jet (5%)
Fake photons (20%)
Background Estimates
All backgrounds estimated with
MC
Z/γ(NLO), di-γ and γ+ jet ←
Pythia6 with CTEQ6L1
Wγ(NLO) ← MadGraph5
CMS-EXO-11-096 CERN-PH-EP-2012-209 16 / 28

MONOPHOTON ANALYSIS
[GeV]TE
200 300 400 500 600 700
Events/GeV
-4
10
-3
10
-2
10
-1
10
1
10
[GeV]TE
200 300 400 500 600 700
Events/GeV
-4
10
-3
10
-2
10
-1
10
1
10
= 7 TeVsCMS,
-1
5.0 fb
DATA
Total uncertainty on Bkg
γνν→γZ
νe→W
(QCD)γMisID-
γ+jets, Wγ
Beam Halo
=1 TeV, n=3)D
SM+ADD(M
Selection:
Trigger: Single photon
Photon: pT > 145 GeV,
|η| < 1.44 (barrel region)
Energy ratio: HCAL/ECAL
< 0.05 within ∆R < 0.15
Lepton veto and hadronic
activity veto
Isolated photons
SR: Emiss
T > 130 GeV, |η| < 4.5
17 / 28

[GeV]χM
1 10
2
10 3
10
]2
-45
10
-43
10
-41
10
-39
10
-37
10
-35
10
Spin Independent
CMS (90%CL)
CDF
XENON100
CDMS II 2011
CDMS II 2010
CoGeNT 2011
= 7 TeVsCMS,
-1
5.0 fb
(a)
[GeV]χM
1 10
2
10 3
10
]2
-45
10
-43
10
-41
10
-39
10
-37
10
-35
10
Spin Dependent
CMS (90%CL)
CDF
SIMPLE 2010
COUPP 2011
)
-
W+
W→χχIceCube (
)-
W+
W→χχSuper-K I+II+III (
= 7 TeVsCMS,
-1
5.0 fb
(b)
Spin-dependent/independent limits correspond to D8 and D5
operators.
Not sensitive to D11 (gluon) operator.
18 / 28

MONO-W/Z ANALYSES (ATLAS/CMS)
Two possible diagrams lead to
interference:
1. ξ = −1: signal enhanced
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)
Same backgrounds as monojet
analysis
Similar data-driven
background estimate
2. CMS: look for single lepton
(mono-W)
W → lν, t¯t, single top,
Drell-Yan, diboson
Background estimated from
MC
CMS-EXO-12-060 ATLAS-CONF-2013-073
19 / 28

MONO-W/Z A.K.A. MONO-FATJET (ATLAS)
[GeV]jetm
50 60 70 80 90 100 110 120
Events/10GeV
0
5
10
15
20
25
30
35
40
45
Data
)+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 GeV
miss
TSR: E
Selection:
Trigger: Emiss
T > 80 GeV
Fat jet: Cambridge-Aachen
algorithm, R = 1.2, ﬁrst two
sub-jets balanced (
√
y > 0.4),
pT > 250 GeV, |η| < 1.2,
mjet = 50 − 120 GeV
Veto leptons (e, µ) and photons
t¯t supression: veto if
>= 2 AntiKt4 jets with
∆R(jetFat, jetAntiKt4) > 0.9 OR
∆φ(Emiss
T , jet) < 0.4 for any
AntiKt4 jets.
SR: Emiss
T > {350, 500} GeV
20 / 28

MONO-W A.K.A. MONO-LEPTON (CMS)
(GeV)TM
500 1000 1500 2000 2500
Events/1GeV
-4
10
-3
10
-2
10
-1
10
1
10
2
10
3
10
4
10
5
10
6
10 Spin Independent
= 200 GeVΛ= 300 GeVχM νl→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:
Trigger: single muon (pT > 40
GeV) or electron (pT > 80 GeV)
triggers
Muons: pT > 45 (ofﬂine) GeV,
|η| < 2.1, isolated
Electrons: pT > 100 (ofﬂine)
GeV, |η| < 1.442 or
1.566 < |η| < 2.5, isolated
Back-to-back kinematics:
0.4 < pT/Emiss
T < 1.5 AND
∆φ(Emiss
T , l) > 0.8π
SR: mT > {1, 1.5, 2} TeV
21 / 28

[GeV]χm
1 10 2
10 3
10
]2
-Ncross-section[cmχ
-46
10
-44
10
-42
10
-40
10
-38
10
-36
10
D5(u=-d):obs D5(u=d):obs
CoGeNT 2010 CDMS low-energy
XENON100 2012 )χχD5:ATLAS 7TeV j(
ATLAS Preliminary = 8 TeVs
-1
L dt = 20.3 fb∫
90% CL
spin independent
(GeV)χM
1 10 2
10 3
10
)2
(cmσ-protonχ
-41
10
-40
10
-39
10
-38
10
-37
10
-36
10
-35
10
=-1ξExpected limit for
=0ξExpected limit for
=+1ξExpected limit for
=-1ξObserved limit for
=0ξObserved limit for
=+1ξObserved limit for
= 8 TeVs-1
CMS Preliminary 2012 20 fb
Spin Independent
Assuming constructive interference gives better limits then ATLAS
monojet and monophoton combined!
Not sensitive to D11 (gluon) operator.
22 / 28

MONO-b
b
g b
X
X
Motivation:
D1 is proportional to the initial
quark mass (D1 ∼
mq
M3
∗
)
By approximate QCD ﬂavour
symmetry the outgoing quark
will be a b
Analysis for 2012 data is
currently underway (ATLAS)
Despite the kinematic and PDF
suppression for producing third
generation quarks
improvement on limits is up to
3 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[cm2
]
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

SUMMARY
WIMPs are well motivated by what we know about Dark Matter and
the observed relic abundance.
EFT’s allow us to search for WIMPs in a model-independent way as
well as compare results from different experiments and signatures.
Mono-X searches at the LHC are competitive and complementary to
direct and indirect detection experiments.
24 / 28

Auxiliary slides
25 / 28

MONOJET ANALYSIS(ATLAS)
[Events/GeV]T
miss
dN/dE
-1
10
1
10
2
10
3
10
4
10
5
10 data 2012
Total BG
) + jetsZ (
) + jetslW (
Multi-jet
Non-collision BG
ll ) + jetsZ (
Dibosons
+ single toptt
=3 TeV (x5)D
ADD n=2, M
=670GeV (x5)*
D5 M=80GeV, M
eV (x5)
-4
=10
G
~=1TeV, M
g~/q~, Mg~/q~+G
~
-1
Ldt=10.5fb
= 8 TeVs
ATLAS Preliminary
[Events/GeV]T
miss
dN/dE
-1
10
1
10
2
10
3
10
4
10
5
10
[GeV]T
miss
E
200 400 600 800 1000 1200
Data/BG
0.5
1
1.5
Orange dashed line indicates
hypothetical DM signal (×5)
Selection:
Trigger: Emiss
T > 80 GeV
At least one primary vetex
Lead jet: pT > 120 GeV, |η| < 2
lepton veto: e, µ
Multijet suppression:
∆φ(Emiss
T , jet2) > 0.5
SR:
Emiss
T > {120, 220, 350, 500} GeV
jet pT > {120, 220, 350, 500} GeV
26 / 28

[ GeV ]χWIMP mass m
1 10 2
10
3
10
]2
WIMP-Nucleoncrosssection[cm
-45
10
-43
10
-41
10
-39
10
-37
10
-35
10
-33
10
-31
10
-29
10
ATLAS , 90%CL-1
= 7 TeV, 4.7 fbs
Spin-independent
XENON100 2012
CDMSII low-energy
CoGeNT 2010
Dirac
)χχj(→qD5: CDF q
Dirac
)χχj(→qD1: q
Dirac
)χχj(→qD5: q
Dirac
)χχj(→D11: gg
theoryσ-1
[ GeV ]χWIMP mass m
1 10 2
10
3
10
]2
WIMP-nucleoncrosssection[cm
-41
10
-40
10
-39
10
-38
10
-37
10
-36
10
-35
10
ATLAS , 90%CL-1
= 7 TeV, 4.7 fbs
Spin-dependent
SIMPLE 2011
Picasso 2012
Dirac
)χχj(→qD8: CDF q
Dirac
)χχj(→qD8: CMS q
Dirac
)χχj(→qD8: q
Dirac
)χχj(→qD9: q
theory
σ-1
Assumption is that DM interacts with SM particles solely by a given
operator
arXiv:1210.4491
27 / 28

]2
[GeV/cχM
1 10
2
10
3
10
]2
-46
10
-44
10
-42
10
-40
10
-38
10
-36
10
-34
10
-32
10
-30
10
-28
10
-27
10
CMS 2012 Vector
CMS 2011 Vector
CDF 2012
XENON100 2012
COUPP 2012
SIMPLE 2012
CoGeNT 2011
CDMSII 2011
CDMSII 2010
CMS Preliminary
= 8 TeVs
Spin Independent
-1
L dt = 19.5 fb∫
2
Λ
q)
µ
γq)(χ
µ
γχ(
]2
Mediator Mass M [TeV/c
-1
10 1 10
[GeV]Λ90%CLlimiton
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
-1
L dt = 19.5 fb∫
2
Λ
q)µ
γq)(χµ
γχ(
CMS (2012) limits for D5 (vector) operator
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

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