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Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Lecture 3: Dark Matter Searchesat Hadron Colliders
Zhao-Huan Yu(余钊焕)ARC Centre of Excellence for Particle Physics at the Terascale,
School of Physics, the University of Melbournehttp://yzhxxzxy.github.io
Frontiers in Dark Matter, Neutrinos, and Particle PhysicsTheoretical Physics Summer School
Sun Yat-Sen University, GuangzhouJuly 27-28, 2017
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 1 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Monojet Searches and Z ′-portal Simplified DM Models
[arXiv:1503.02931, PRD]
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 2 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
DM Production
g
g
bχ02
ℓ−
g qχ+
1 νℓ′
g
g
bb
qq′
ℓ+
ℓ−
χ01
χ01
νℓ′
ℓ′+
q
q
g
χ
χ
q
Social dark matterAccompanied by other new particles
Complicated decay chainsDecay products of other particles
Various final states(jets+ leptons+ /E, ...)
Maverick dark matterDM particle is the only new particle
reachable at the collision energyDirect production
Mono-X+ /E final states(monojet, mono-γ, mono-W/Z , ...)
[From Rocky Kolb’s talk]
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 3 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
DM Direct Production at Hadron Colliders
q
q
g
χ
χ
q
g
g
q
χ
χ
q
Monojet+ /ET
q
q
q
χ
χ
γ/Z
γ/Z
q
q
χ
χ
γ/Z
Monophoton/mono-Z + /ET
q
q
q′
χ
χ
W
W
q
q′
χ
χ
W
Mono-W + /ET
Sensitive to the DM couplings toquarks, gluons
photons, Z bosonsW± bosons
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 4 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Monojet+ /ET Channel at the LHC
[GeV]χM1 10
2103
10
]2
-Nu
cle
on
Cro
ss S
ectio
n [
cm
χ
-4610
-4510
-4410
-4310
-4210
-4110
-4010
-3910
-3810
-3710
-3610
-1CMS, 90% CL, 8 TeV, 19.7 fb
-1CMS, 90% CL, 7 TeV, 5.0 fb
LUX 2013
superC
DM
S
CD
MS
lite
XENON100
COUPP 2012
SIMPLE 2012
CoGeNT 2011
CDMS II
CMS
Spin Independent
2Λ
q)µ
γq)(χµ
γχ(
Vector
3Λ4
2)νµ
a(G
sαχχ
Scalar
-1CMS, 90% CL, 8 TeV, 19.7 fb
[GeV]χM1 10
2103
10
]2
-Nu
cle
on
Cro
ss S
ectio
n [
cm
χ
-4610
-4510
-4410
-4310
-4210
-4110
-4010
-3910
-3810
-3710
-3610
-1CMS, 90% CL, 8 TeV, 19.7 fb
-1CMS, 90% CL, 7 TeV, 5.0 fb
COUPP 2012
-W+
IceCube W
SIMPLE 2012
-W+
Super-K W
CMS
Spin Dependent
2Λ
q)5
γµ
γq)(χ5
γµ
γχ(Axial-vector operator
[CMS coll., arXiv:1408.3583]
In the context of effective field theory, effectiveoperators can be used to describe interactionsbetween DM and quarks, which could induce themonojet+ /ET signal at the LHC, as well asDM-nucleus scattering signals in DM directdetection experiments
χγµχ qγµq operators: upper right plotThe 8 TeV LHC sensitivity is better than directdetection only when mχ ≲ 3 GeV
χγµγ5χ qγµγ5q operators: lower right plotThe 8 TeV LHC sensitivity is much better thandirect detection
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 5 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
A Little Further than Effective Operators
q
q
g
χ
χ
q
Effective operators
⇒q
Z ′
q
g
χ
χ
q
Z ′-portal simplified models
The valid range of effective field theory is limited: if the momentumtransfer in scattering is sufficient large (comparable to or even larger thanthe mediator mass), the effective operator approach would break downIn this case, simplified models involving only renormalizable operatorswould give a more reasonable description
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 6 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Z ′-portal DM Simplified Models
We discussed a class of Z ′-portal simplified models, where the mediator Z ′ isa vector boson
FV model: Dirac fermion χ, vector current interactions
LFV =∑
q
gq Z ′µqγµq+ gχZ ′µχγµχ
FA model: Dirac fermion χ, axial vector current interactions
LFA =∑
q
gq Z ′µqγµγ5q+ gχZ ′µχγµγ5χ
SV model: complex scalar χ, vector current interactions
LSV =∑
q
gq Z ′µqγµq+ i gχZ ′µ[χ∗∂ µχ − (∂ µχ∗)χ]
We would like to investigate the sensitivity of the monojet+ /ET channel atfuture hadron colliders with ps = 33 TeV (VHE-LHC), 50 TeV (SPPC), and100 TeV (FCC-hh)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 7 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Event Selection in the monojet+ /ET ChannelF
raction o
f events
E ⁄ T (GeV)
pp collider, √s = 50 TeV, monojet + E ⁄ T
FA
FV
SV
Z + jets
W + jets
10-5
10-4
10-3
10-2
10-1
100
0 1000 2000 3000 4000 5000 6000
Fra
ction o
f events
E ⁄ T (GeV)
pp collider, √s = 100 TeV, monojet + E ⁄ T
FA
FV
SV
Z + jets
W + jets
10-5
10-4
10-3
10-2
10-1
100
1000 2000 3000 4000 5000 6000
Signalbenchmarkpoint:mχ = 1 TeV
mZ ′ = 5 TeV
gq = gχ = 0.1
DM production signal: pp→ Z ′(∗)(→ χχ/χχ∗) + jetsMain SM backgrounds: pp→ Z(→ νν) + jets, pp→W (→ lν) + jets
/ET > 1.6/1.8/2.6 TeV; Jet number njet ≥ 1; the leading jet j1 satisfies |η( j1)|< 2.4and pT( j1)> 1.6/1.8/2.6 TeV for ps = 33/50/100 TeV
Reject events containing > 2 jets with pT > 100 GeV and |η|< 4; a second jet isallow if it satisfies ∆ϕ( j1, j2)< 2.5 for suppressing the QCD multi-jet backgroundReject events containing isolated electrons, muons, τ-jets, and photons withpT > 20 GeV and |η|< 2.5
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 8 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
SPPC vs. DM Direct Detectionm
χ (G
eV
)
mZ’ (GeV)
50TeV pp collider, 3 ab-1
, FV
LUX 2013
SuperCDMS
Xenon 100
Xenon 1T
100
101
102
103
104
105
101
102
103
104
105
g q=g χ
=0.1
gq=gχ=0.3
gq=gχ=0.5
gq=gχ=1.0
mχ (G
eV
)
mZ’ (GeV)
50TeV pp collider, 3 ab-1
, FA
COUPP 2012
SIMPLE 2011
PICASSO 2012
Super-K W+W
−
IceCube W+W
−
100
101
102
103
104
105
106
101
102
103
104
mχ (G
eV
)
mZ’ (GeV)
50TeV pp collider, 3 ab-1
, SV
LUX 2013
SuperCDMS
Xenon 100
Xenon 1T
100
101
102
103
104
105
101
102
103
104
105
Dashed lines: 90% CL expected exclu-sion limits at the SPPC
Solid lines: 90% CL exclusion limitsfrom direct detection for
gq = gχ = 0.5
Light red region: unitarity violation forgq = gχ = 1
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 9 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
SPPC vs. DM Relic Densitym
Z’
(GeV
)
mχ (GeV)
50 TeV pp collider, 3 ab-1
, FV
Relic density
Collider
100
101
102
103
104
100
101
102
103
104
gq=
gχ=
0.5
gq=
gχ=
0.3
gq=
gχ=
0.1
m Z’ = 2 m χ
mZ
’ (G
eV
)
mχ (GeV)
50 TeV pp collider, 3 ab-1
, FA
Relic density
Collider
100
101
102
103
104
100
101
102
103
104
gq=gχ
=0.5gq=gχ
=0.3
gq=gχ=0.1
m Z’ = 2 m χ
mZ
’ (G
eV
)
mχ (GeV)
50 TeV pp collider, 3 ab-1
, SV
Relic density
Collider
100
101
102
103
104
100
101
102
103
104
gq=
gχ=
0.5
gq=
gχ=
0.3
gq=
gχ=
0.1
m Z’ = 2 m χ
Dashed lines: 90% CL expectedexclusion limits at the SPPC
Solid lines: observed value of theDM relic density
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 10 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
LHC Searches for τ-portal DM Models
[arXiv:1410.3347, PRD]
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 11 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Excess of GeV Continuous Spectrum γ-rays
20 40 60 80 100
10-26
10-25
MDM @GeVD
XΣv
\@cm
3s-
1D
KRA, gNFW HΓ = 1.26L
bb Χmin2 dof = 1.44
ææ
æ
æ
ææ
æ
ææ
æ
æ
æ
æ
æ æ
æ
æ
æ æ æ
æ
æ æ
æ
æ
100 101 102-1.
0.
1.
2.
3.
4.
EΓ @GeVD
10
6
EΓ2
dF
dE
Γd
W@G
eVcm
-2
s-1
sr-
1D
MDM = 37.8 GeV
XΣ v\ = 2.10 10-26 cm3s-1
5 10 15 20 25 30
10-26
10-25
MDM @GeVDXΣ
v\@
cm3
s-1
D
KRA, gNFW HΓ = 1.26L
BRΤ = 100% Χmin2 dof = 3.4
BRΜ = 0%BRe = 0%
ææ
æ
æ
ææ
æ
ææ
æ
æ
æ
æ
æ æ
æ
æ
æ æ æ
æ
æ æ
æ
æ
100 101 102-1.
0.
1.
2.
3.
4.
EΓ @GeVD
10
6
EΓ2
dF
dE
Γd
W@G
eVcm
-2
s-1
sr-
1D
MDM = 8 GeV
XΣ v\ = 6.96 10-27 cm3s-1
[Cirelli et al., arXiv:1407.2173]
Since 2009, several groups reported an excessof continuous spectrum γ-rays in the GalacticCenter (GC) region, peaking at a few GeV aftersubtracting well-known astrophysical backgroundsin the Fermi-LAT data
Interpretation with DM annihilation into bb:
mχ ≃ 30− 40 GeV
⟨σannv⟩ ∼ 10−26 cm3 s−1
Interpretation with DM annihilation into τ+τ−:
mχ ∼ 9 GeV
⟨σannv⟩ ∼ 5× 10−27 cm3 s−1
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 12 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
τ-portal Simplified DM Models
φ
χ
χ
τ−
τ+
DFDM: annihilation
ψ
χ
χ∗
τ−
τ+
CSDM: annihilation
We studied four τ-portal simplified modelsinvolving a mediator with additive quantumnumbers identical to the right-handed τ−
We interpreted the GC GeV excess signal asDM annihilation into τ+τ−, and discussed howto test this interpretation at the LHC
Spin-1/2 fermion χ, spin-0 mediator ϕ:Lϕ = λϕτRχL + h.c.
DFDM model: χ is a Dirac fermionMFDM model: χ is a Majorana fermion
Spin-0 scalar χ, spin-1/2 mediator ψ:Lψ = κχτRψL + h.c.
CSDM model: χ is a complex scalarRSDM model: χ is a real scalar
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 13 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
DM Annihilation into τ+τ− in the Low Velocity Limit
DFDM model:12⟨σannv⟩= λ4 m2
χβτ
64π(m2ϕ+m2
χ−m2
τ)2≃ 5×10−27 cm3 s−1
mχ
9.4 GeV
2 λ
mϕ/179 GeV
4MFDM model:
⟨σannv⟩= λ4 m2τβτ
32π(m2ϕ+m2
χ−m2
τ)2≃ 5× 10−27 cm3 s−1
λ
mϕ/93 GeV
4
Helicity suppression
CSDM model:12⟨σannv⟩= κ4 m2
τβ3τ
32π(m2ψ+m2
χ−m2
τ)2≃ 5× 10−27 cm3 s−1
κ
mψ/93 GeV
4
Helicity suppression
RSDM model:
⟨σannv⟩= κ4 m2τβ3τ
4π(m2ψ+m2
χ−m2
τ)2≃ 5× 10−27 cm3 s−1
κ
mψ/156 GeV
4
Helicity suppression
(βτ ≡q
1−m2τ/m
2χ ; mτ≪ mχ ≪ mϕ , mψ approximation)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 14 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
DM Annihilation into τ+τ− in the Low Velocity Limit
DFDM model:12⟨σannv⟩= λ4 m2
χβτ
64π(m2ϕ+m2
χ−m2
τ)2≃ 5×10−27 cm3 s−1
mχ
9.4 GeV
2 λ
mϕ/179 GeV
4MFDM model:
⟨σannv⟩= λ4 m2τβτ
32π(m2ϕ+m2
χ−m2
τ)2≃ 5× 10−27 cm3 s−1
λ
mϕ/93 GeV
4Helicity suppression
CSDM model:12⟨σannv⟩= κ4 m2
τβ3τ
32π(m2ψ+m2
χ−m2
τ)2≃ 5× 10−27 cm3 s−1
κ
mψ/93 GeV
4Helicity suppression
RSDM model:
⟨σannv⟩= κ4 m2τβ3τ
4π(m2ψ+m2
χ−m2
τ)2≃ 5× 10−27 cm3 s−1
κ
mψ/156 GeV
4Helicity suppression
(βτ ≡q
1−m2τ/m
2χ ; mτ≪ mχ ≪ mϕ , mψ approximation)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 14 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Direct Detection
τ
φ
τ
γ
χ
χ
A
ZN
A
ZN
φ
τ
φ
γ
χ
χ
A
ZN
A
ZN
DM-nucleus scattering for DFDM(ϕ↔ψ: DM-nucleus scattering for CSDM)
SI DM-nucleus scattering cross sections in the DFDM and CSDM models:
σDFDMχN =
Z2e2B2µ2χN
πA2, σCSDM
χN =Z2e2C2µ2
χN
8πA2, µχN ≡ mχmN
mχ +mN
Form factor B ≃ − λ2e64π2m2
ϕ
h12 +
23 ln
m2τ
m2ϕ
imatches [χγµ(1− γ5)∂ νχ + h.c.]Fµν
Form factor C ≃ − κ2e16π2m2
ψ
h1+ 2
3 ln
m2τ
m2ψ
imatches (∂ µχ)(∂ νχ∗)Fµν
Unconstrained by experiments:MFDM: the leading contributioncomes from an anapole momentoperator [−χγµγ5∂
νχ + h.c.]Fµν
RSDM: the leading contributioncomes from two-loop diagramsvia exchanging two photons
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 15 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Mediator Pair Production at the LHC
γ/Z
φ
φ∗
q
q
τ−
χ
χ
τ+
DFDM or MFDM
γ/Z
ψ
ψ
q
q
τ−
χ
χ
τ+
CSDM or RSDM10-2
10-1
100
101
102
103
104
100 200 300 400 500 600
Pro
du
ctio
n c
ross s
ectio
n
(fb
)
mφ or mψ (GeV)
LHC, mediator pair production
DFDM / MFDM
(scalar mediator)
CSDM / RSDM
(fermionic mediator)
8 TeV
14 TeV
As the mediators ϕ and ψ carry Q = Y = −1, theycould be produced at the LHC through Drell-Yanprocesses exchanging s-channel γ or Z , and thendecay into τ± and χWe found that the 8 TeV LHC data cannotexplore the interesting regions in these models,and went further to investigate the LHC sensitivityat ps = 14 TeV with tight τh-tagging techniques
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 16 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
14 TeV LHC Searches for pp→ ϕϕ∗/ψψ→ τ+τ−χχ
Fra
ction o
f events
mT2 (GeV)
LHC, 14 TeV, 2τh + E ⁄ T
Diboson
Top pair
W + jets
DFDM
MFDM
CSDM
RSDM
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0 50 100 150 200 250 300
Signals:DFDM modelmϕ = 225 GeV
MFDM modelmϕ = 250 GeV
CSDM modelmψ = 300 GeV
RSDM modelmψ = 200 GeV
2τh + /ET channel: two opposite-sign tau-jet (τh);without any other particle; mT2 > 90 GeV
τℓτh + /ET channel: one τh and one light lepton(ℓ= µ, e) with opposite signs; without any otherparticle; mT2 > 90 GeV
2τℓ + /ET channel: two opposite-sign light leptons;|mℓℓ −mZ |> 10 GeV for the same-favor case;without any other particle; mT2 > 100 GeV
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 17 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
14 TeV LHC Searches for pp→ ϕϕ∗/ψψ→ τ+τ−χχ
Fra
ction o
f events
mT2 (GeV)
LHC, 14 TeV, 2τh + E ⁄ T
Diboson
Top pair
W + jets
DFDM
MFDM
CSDM
RSDM
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0 50 100 150 200 250 300
Fra
ction o
f events
mT2 (GeV)
LHC, 14 TeV, τlτh + E ⁄ T
Diboson
Top pair
W + jets
DFDM
MFDM
CSDM
RSDM
0.00
0.05
0.10
0.15
0.20
0.25
0 50 100 150 200 250
Signals:DFDM modelmϕ = 225 GeV
MFDM modelmϕ = 250 GeV
CSDM modelmψ = 300 GeV
RSDM modelmψ = 200 GeV
2τh + /ET channel: two opposite-sign tau-jet (τh);without any other particle; mT2 > 90 GeV
τℓτh + /ET channel: one τh and one light lepton(ℓ= µ, e) with opposite signs; without any otherparticle; mT2 > 90 GeV
2τℓ + /ET channel: two opposite-sign light leptons;|mℓℓ −mZ |> 10 GeV for the same-favor case;without any other particle; mT2 > 100 GeV
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 17 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
14 TeV LHC Searches for pp→ ϕϕ∗/ψψ→ τ+τ−χχ
Fra
ction o
f events
mT2 (GeV)
LHC, 14 TeV, 2τh + E ⁄ T
Diboson
Top pair
W + jets
DFDM
MFDM
CSDM
RSDM
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0 50 100 150 200 250 300
Fra
ction o
f events
mT2 (GeV)
LHC, 14 TeV, τlτh + E ⁄ T
Diboson
Top pair
W + jets
DFDM
MFDM
CSDM
RSDM
0.00
0.05
0.10
0.15
0.20
0.25
0 50 100 150 200 250
Fra
ction o
f events
mT2 (GeV)
LHC, 14 TeV, 2τl + E ⁄ T
Diboson
Top pair
DFDM
MFDM
CSDM
RSDM
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0 50 100 150 200
Signals:DFDM modelmϕ = 225 GeV
MFDM modelmϕ = 250 GeV
CSDM modelmψ = 300 GeV
RSDM modelmψ = 200 GeV
2τh + /ET channel: two opposite-sign tau-jet (τh);without any other particle; mT2 > 90 GeV
τℓτh + /ET channel: one τh and one light lepton(ℓ= µ, e) with opposite signs; without any otherparticle; mT2 > 90 GeV
2τℓ + /ET channel: two opposite-sign light leptons;|mℓℓ −mZ |> 10 GeV for the same-favor case;without any other particle; mT2 > 100 GeV
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 17 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Resultsλ
mφ (GeV)
Dirac fermionic DM, scalar mediator
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
100 200 300 400 500 600
LE
P
LUX
GC GeV excess
λ
mφ (GeV)
Majorana fermionic DM, scalar mediator
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
100 200 300 400 500 600
LE
P
GC GeV excess
DFDM MFDM
κ
mψ (GeV)
Complex scalar DM, fermionic mediator
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
100 200 300 400 500 600
LE
P
LUX
GC GeV excess
HL-LHC
(3000 fb-1
)
5σ
d
isco
ve
ry
95
% C
L e
xclu
sio
n
κ
mψ (GeV)
Real scalar DM, fermionic mediator
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
100 200 300 400 500 600
LE
P
GC GeV excess
HL-LHC
(3000 fb-1
)
5σ
d
isco
ve
ry
95
% C
L e
xclu
sio
n
CSDM RSDM
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 18 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Stop Searches and DM Coannihilation
[arXiv:1211.2997, PRD]
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 19 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Problem of the Standard Model (SM)
A ∼125 GeV SM-like Higgs boson has been discovered
The quantum correction of SM Higgs boson mass ∆m2H suffers from
quadratic divergence⇓
Hierarchy problem⇓
New physics at TeV scale(supersymmetry, extra dimension, little Higgs, ...)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 20 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Stops in Supersymmetric (SUSY) Models
The lighter stop t1 is probably reachable in early LHC searches.In order to cancel the large radiative corrections to mH from the topquark loop without fine tuning, the stops t1,2 need to be light enough.t1 can be the lightest colored supersymmetric particle due to the largetop Yukawa coupling and large mass splitting terms in many SUSYmodels.
In the following work, the direct production of t1 t∗1 pairs at the LHC isconsidered: pp→ t1 t∗1 + jets
m t1[GeV] 200 400 600
7TeV, σNLO [fb] 11837 205 128TeV, σNLO [fb] 17296 342 23
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 21 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Stop Direct Searches
[GeV]1t
~m200 250 300 350 400 450 500 550 600 650
10
r¾+mt
< m
1t~m
150 200 250 300 350 400 450 50
)1
0r¾ m×
= 2
1±r¾ ( m
1±r¾+m
b < m1t~m
( = 106 GeV)1±r¾ > m
1
0r¾
m
< 106 GeV 1±r¾ m
( = 150 GeV)1±r¾ > m
1
0r¾
m
-10)
1t~ =
m1±
r¾
( m1±
r¾
> m
10
r¾ m
[GeV
]10 r¾
m
0
50
100
150
200
250
300
350 =8 TeVs -1 = 13 fbintL
1
0r¾
m× = 2 ±
1rm
-1 = 13 fbintL - 10 GeV
1t~ = m±
1rm
-1 = 13 fbintL
= 150 GeV±
1rm
-1 = 13 fbintL = 106 GeV±
1rm
-1 = 4.7 fbintL
-1 = 4.7 fbintL -1 = 13 fbintL
ATLAS Preliminary
Status: December 2012
=7 TeVs -1 = 4.7 fbintL1L ATLAS-CONF-2012-166-1L ATLAS-CONF-2012-1662L ATLAS-CONF-2012-1671L ATLAS-CONF-2012-166
0L [1208.1447], 1L [1208.2590], 2L [1209.4186]2L [1208.4305], 1-2L [1209.2102]--1-2L [1209.2102]
production1t~1t
~
10
r¾+(*) WA1±r¾,
1±r¾ b+A 1t
~10
r¾ t A1t~
10
r¾ t A1t~
= 106 GeV±1
r, m
1±r¾ b+A 1t
~
= 150 GeV±1
r, m
1±r¾ b+A 1t
~
- 10 GeV1t
~ = m±1
r, m
1±r¾ b+A 1t
~
10
r¾ m× = 2 ±
1r
, m1±r¾ b+A 1t
~
Observed limits)theomObserved limits (-1
Expected limits
Assuming some simplified models in which stops can be easily detectedExcluding stops up to ∼ 580 GeV
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 22 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Dark Matter (DM)
Not to violate baryon number B or lepton number L
(proton decay, flavor physics constraints)⇓
R-parity conserved SUSY [PR = (−1)3(B−L)+2s]⇓
The lightest SUSY particle (LSP) is stable.⇓
If the LSP is electrically neutral, such as χ01 , it would be an attractive
candidate for non-baryonic dark matter.
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 23 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
DM Relic Density
ΛCDM model fitted by 7-year WMAP data: [Ap. J. Suppl. 192, 16 (2011)]
ΩCDMh2 = 0.1109, Ωbaryonh2 = 0.02258, ΩΛ = 0.734
(Cold DM ∼ 21.1%, baryons ∼ 4.3%, dark energy ∼ 74.6%)
For thermal produced DM, ΩCDM∝ ⟨σannv⟩−1.
In many SUSY models, most likely the lightest neutralino χ01 is the LSP.
However, the sfermion exchange process χ01 χ
01 → f f has the helicity
suppression issue. The self-annihilation cross section σann of χ01 is
generally not large enough to yield the observed relic density ΩCDM.
Additional mechanisms are needed (resonance, coannihilation, ...).
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 24 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
CMSSM Case
100 1000 2000
0
1000
2000
100 1000 2000
0
1000
2000
m0 (
GeV
)
m1/2 (GeV)
tan β = 50 , µ > 0 (A0 = 0)
¬
®
noEW
SB
stau LSP
[Ellis, Olive, Sandick, arXiv:0704.3446]
¬ Higgs funnel region2mχ0
1≃ mA0 or mh0 or mH0
χ01 annihilates via a resonance
Focus point regionχ0
1 is a bino-higgsino orbino-wino mixturemχ0
1∼ mχ±1 or mχ0
2
χ01 coannihilates with χ±1 or χ0
2
® Sfermion coannihilation regionmχ0
1∼ mτ1
or m t1
χ01 coannihilates with τ1 or t1
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 25 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Coannilation Scenarios
In general, in order to yield the desired dark matter relic density bycoannihilation mechanism, the mass of the next-to-lightest SUSY particle(NLSP) mNLSP should satisfies
mNLSP −mχ01
mχ01
≲ 20%.
[Profumo, Yaguna, arXiv:hep-ph/0407036]
In this work, we study 3 coannihilation scenarios with a light stop.1 t1-χ0
1 coannihilation: mχ01∼ m t1
2 χ±1 -χ01 coannihilation: mχ0
1∼ mχ±1 < m t1
3 τ1-χ01 coannihilation: mχ0
1∼ mτ1
< m t1
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 26 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
MC Simulation
Credit: Frank Krauss
Hard process⇑
MadGraph5
MLM matching
Parton shower⇑
Pythia 6.4⇓
Hadronization & decay
PGS4 ⇒ Detector simulation
Prospino2, MCFM ⇒ NLO K-factorZhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 27 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Scenario 1: t1-χ01 Coannihilation
The lighter stop t1 is the NLSP: mχ01∼ m t1
t1 decay channels: t1→ tχ01 , bW χ0
1 , cχ01 , f f ′bχ0
1For mχ0
1+mc < m t1
< mχ01+mb +mW , assume t1→ cχ0
1 (100%).
t1t∗1
p
p
c (soft)
χ0
1
χ0
1
q/g
c (soft)
LHC searching channel: monojet + /ET
SM backgrounds: Z(→ νν) + jets, W (→ ℓν) + jets, ...
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 28 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
t1-χ01 Coannihilation: t1→ cχ0
1
m∼ χ
10
(Ge
V)
m∼t1
(GeV)
ATLAS 4.7 fb-1
, 95% CL, SR1
ATLAS 4.7 fb-1
, 95% CL, SR2
ATLAS 4.7 fb-1
, 95% CL, SR3
ATLAS 4.7 fb-1
, 95% CL, SR4
50
100
150
200
250
300
50 100 150 200 250 300
m∼t 1
= m∼χ 10 +
m c
m∼t 1
= m∼χ 10 +
m W + m b
mass diff. 20%
CDF 2.6 fb
-1 , 95% C
L
LEP
ATLAS 7TeV, 4.7fb−1, monojet + /ET
[arXiv:1210.4491]
Analysis instance:(ATLAS Signal Region 2)Lepton veto/ET > 220GeVJet 1: pT > 220GeV, |η|< 2Jet 3: pT < 30GeV∆ϕ( j2, /ET) > 0.5
⇓SM bkg: 8800± 400Observed: 8631σBSM
vis < 170 fb (95% CL)
(σvis ≡ σ · A · ε= production cross section× acceptance× efficiency)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 29 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
t1-χ01 Coannihilation: t1→ cχ0
1
m∼ χ
10
(Ge
V)
m∼t1
(GeV)
LHC √s = 8 TeV, monojet + E ⁄ T, 20 fb-1
S/√ B = 5 (37.9 fb)
S/√ B = 3 (22.7 fb)
50
100
150
200
250
300
350
400
150 200 250 300 350 5
10
20
50
100
200
Exp
ecte
d v
isib
le c
ross s
ectio
n
σ ⋅
A ⋅
ε (
fb)
m∼t 1 = m
∼χ 10 + m c
m∼t 1 = m
∼χ 10 + m W
+ m b
LHC 8TeV, 20 fb−1
Kinematic cuts:Lepton veto/ET > 300GeVJet 1: pT > 150GeV,
|η|< 2.4Jet 3: pT < 50GeV∆ϕ( j1, j2) < 2.5
⇓SM bkg: 22944(13939 Z(→ νν) + jets, 9005 W (→ ℓν) + jets)
⇓σBSM
vis < 22.7fb for S/p
B < 3, σBSMvis < 37.9fb for S/
pB < 5
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 30 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
t1-χ01 Coannihilation: t1→ cχ0
1
m∼ χ
10
(Ge
V)
m∼t1
(GeV)
ATLAS 7 TeV, 4.7 fb-1
, 95% CL
CMS 7 TeV, 5.0 fb-1
, 95% CL
LHC 8 TeV, 20 fb-1
, S/√ B = 5
LHC 8 TeV, 20 fb-1
, S/√ B = 3
50
100
150
200
250
300
350
50 100 150 200 250 300 350
m∼t 1
= m∼χ 1
0 + m c
m∼t 1
= m∼χ 1
0 + m W
+ m b
m∼t 1 = 1.2 m
∼χ 10
CDF 2.6 fb
-1
LEP
For “coannihilation region” (m t1< 1.2mχ0
1),
7 TeV, ∼ 5 fb−1 → m t1≳ 150− 220GeV (95% CL)
8 TeV, 20 fb−1 → m t1≳ 270− 340GeV (S/
pB < 3)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 31 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Scenario 2: χ±1 -χ01 Coannihilation
χ01
χ01
t1
t∗1
p
p
χ+1
b
χ−
1
b
f1 (soft)
f2 (soft)
f3 (soft)
f4 (soft)
The lighter chargino χ±1 is the NLSP: mχ01∼ mχ±1 < m t1
Fixing (mχ±1 −mχ01)/mχ0
1= 10%, for mb +mχ±1 < m t1
< mχ01+mt ,
assume t1→ bχ±1 (100%) and χ±1 → f f ′χ01 (100%).
LHC searching channel: 1-2 b-jets + /ET
SM backgrounds: top pair, Z/W + heavy flavors, single top, ...
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 32 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
χ±1 -χ01 Coannihilation: t1→ bχ+1 , χ+1 → f f ′χ0
1
ATLAS 7 TeV, 2 b-jets + E ⁄ T, 4.7 fb-1
(m∼χ1
± = 1.1 m∼χ1
0)
SR2, 2.29 fb (95% CL)
150 200 250 300 350 400
m∼t1 (GeV)
100
150
200
250
300
350
400
m∼ χ
1±
(Ge
V)
0.02
0.05
0.2
0.5
2
5
20
0.01
0.1
1
10
Exp
ecte
d v
isib
le c
ross s
ectio
n
σ ⋅ A
⋅ ε
(f
b)
m∼t 1
= m∼χ 1
± + m b
m∼t 1
= m
∼χ 10 +
m t
ATLAS 7TeV, 4.7 fb−1, 2b-jets + /ET
[ATLAS-CONF-2012-106]
Analysis instance:(ATLAS Signal Region 2)Lepton veto/ET > 200GeVnb-jet = 2 (pT > 60GeV)Jet 3: pT < 50GeV/ET/meff > 0.25mCT > 100GeV∆ϕ( j1,2, /ET) > 0.4
⇓SM bkg: 27± 7Observed: 20σBSM
vis < 2.29fb (95% CL)
(The contransverse mass mCT defined as m2CT = (E
j1T + E j2
T )2 − (p j1
T − p j2T )
2)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 33 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
χ±1 -χ01 Coannihilation: t1→ bχ+1 , χ+1 → f f ′χ0
1
CMS 7 TeV, b-jets + E ⁄ T, 4.98 fb-1
(m∼χ1
± = 1.1 m∼χ1
0)
1BL, 20.6 fb (95% CL)
140 160 180 200 220 240 260 280 300 320
m∼t1 (GeV)
100
150
200
250
300
m∼ χ
1±
(Ge
V)
2
5
20
50
10
Exp
ecte
d v
isib
le c
ross s
ectio
n
σ ⋅ A
⋅ ε
(f
b)
m∼t 1
= m∼χ 1
± + m b
m∼t 1
= m∼χ 1
0 + m t
CMS 7TeV, 4.98 fb−1, b-jets + /ET
[arXiv:1208.4859]
Analysis instance:(CMS Signal Region 1BL)Lepton veto/ET > 250GeVHT > 400GeVnjet ≥ 3 (pT > 50GeV)nb-jet ≥ 1 (pT > 30GeV)∆ϕmin > 4.0
⇓SM bkg: 477± 26± 38Observed: 478σBSM
vis < 20.6 fb (95% CL)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 34 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
χ±1 -χ01 Coannihilation: t1→ bχ+1 , χ+1 → f f ′χ0
1
dN
/dm
jjj
(Eve
nts
/ G
eV
)
mjjj (GeV)
LHC √s = 8 TeV, ≥1 b-jets + E ⁄ T, 20 fb-1
(m∼χ1± = 1.1 m∼χ1
0)
top pair
Z
W
single top(m~
t1, m~χ1
±) = (260, 100)
(m~t1
, m~χ1±) = (250, 245)
10-2
10-1
100
101
102
0 200 400 600 800 1000
LHC 8TeV, 20 fb−1
Kinematic cuts:Lepton veto/ET > 200GeVHT > 300GeVnjet ≥ 3 (pT > 60GeV)nb-jet ≥ 1 (pT > 30GeV)∆ϕ( j1,2,3, /ET) > 0.4m j j j /∈ (130, 200)GeV
(Pick up a pair of jets with m j j > 60GeV and smallest ∆R, and m j j j is the invariantmass of this pair of jets and a third jet which is closest to them.)m j j j /∈ (130, 200)GeV rejects 47% (31%) of top pair (single top) events,while only rejects 20% of stop events for (m t1
, mχ±1 ) = (260, 100)GeV.
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 35 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
χ±1 -χ01 Coannihilation: t1→ bχ+1 , χ+1 → f f ′χ0
1
LHC √s = 8 TeV, ≥1 b-jets + E ⁄ T, 20 fb-1
(m∼χ1± = 1.1 m∼χ1
0)
S/√ B = 5 (14.0 fb)
S/√ B = 3 (8.4 fb)
150 200 250 300 350 400 450
m∼t1
(GeV)
100
150
200
250
300
350
400
450
m∼ χ
1± (
Ge
V)
0.5
2
5
20
50
100
1
10
Exp
ecte
d v
isib
le c
ross s
ectio
n
σ ⋅
A ⋅
ε (
fb)
m∼t 1
= m∼χ 1
± + m b
m∼t 1
= m
∼χ 10 +
m t
SM bkg: 3132(2269 top pair390 Z + heavy flavor353 W + heavy flavor120 single top)
σBSMvis < 8.4 fb for S/
pB < 3, σBSM
vis < 14.0 fb for S/p
B < 5
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 36 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
χ±1 -χ01 Coannihilation: t1→ bχ+1 , χ+1 → f f ′χ0
1
m∼ χ
1± (
Ge
V)
m∼t1
(GeV)
CMS 7 TeV, b-jets + E ⁄ T, 4.98 fb-1
, 1BL, 95% CL
ATLAS 7 TeV, 2 b-jets + E ⁄ T, 2.05 fb-1
, mCT > 100 GeV, 95% CL
ATLAS 7 TeV, 2 b-jets + E ⁄ T, 4.7 fb-1
, SR3a, 95% CL
ATLAS 7 TeV, 2 b-jets + E ⁄ T, 4.7 fb-1
, SR2, 95% CL
LHC 8 TeV, 20 fb-1
, ≥1 b-jets + E ⁄ T, S/√ B = 5
LHC 8 TeV, 20 fb-1
, ≥1 b-jets + E ⁄ T, S/√ B = 3
100
150
200
250
300
350
400
450
150 200 250 300 350 400 450
m∼t 1
= m∼χ 1
± + m b
m∼t 1
= m∼χ 1
0 + m t
m∼χ1± = 1.1 m∼χ1
0
7 TeV, ∼ 5 fb−1 → exclusion up to m t1≃ 380GeV (95% CL)
8 TeV, 20 fb−1 → exclusion up to m t1≃ 430GeV (S/
pB > 3)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 37 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Scenario 3: τ1-χ01 Coannihilation
χ01
χ01
t1
t∗1
p
p
τ+1
b
τ−1
b
ντ
ντ
τ+ (soft)
τ− (soft)
The lighter stau τ±1 is the NLSP: mχ01∼ mτ1
< m t1
Fixing (mτ1−mχ0
1)/mχ0
1= 10%, for mb +mτ1
< m t1< mχ0
1+mt ,
assume t1→ bτ+1ντ (100%) and τ±1 → τ±χ01 (100%).
LHC searching channel: 1-2 b-jets + /ET
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 38 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
τ1-χ01 Coannihilation: t1→ bτ+1ντ, τ
+1 → τ+χ0
1
m∼ τ 1
(G
eV
)
m∼t1
(GeV)
CMS 7 TeV, b-jets + E ⁄ T, 4.98 fb-1
, 1BL, 95% CL
ATLAS 7 TeV, 2 b-jets + E ⁄ T, 4.7 fb-1
, SR3a, 95% CL
LHC 8 TeV, 20 fb-1
, ≥1 b-jets + E ⁄ T, S/√ B = 5
LHC 8 TeV, 20 fb-1
, ≥1 b-jets + E ⁄ T, S/√ B = 3
100
150
200
250
300
350
400
150 200 250 300 350 400
m∼t 1
= m∼τ 1
+ m b
m∼t 1
= m∼χ 1
0 + m t
m∼τ1 = 1.1 m∼χ1
0
The neutrinos ντ(ντ) take away some energy so that b-jets become soft.
7 TeV, ∼ 5 fb−1 → exclusion up to m t1≃ 220GeV (95% CL)
8 TeV, 20 fb−1 → exclusion up to m t1≃ 370GeV (S/
pB > 3)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 39 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
LHC Searches for Singlino-Higgsino DM in the NMSSM
[arXiv:1606.02149, PRD]
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 40 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Motivation
Shortages of the Standard Model (SM)Radiative correction to the Higgs mass term ⇒ hierarchy problemNo cold dark matter (DM) candidate
Supersymmetry (SUSY) and R-parity conservationElegant solution to the hierarchy problemLightest supersymmetric particle (LSP) ⇒ DM candidate
No evidence of superpartners in LHC Run 1 dataPush gluino and squark mass limits up to ≳O(1) TeVElectroweak (EW) production rates are much lower; m∼O(100) GeV EWsuperpartners could hide in Run 1 searches
LHC Run 2 and further searches are promising to directly probean O(100) GeV-scale neutralino-chargino sector
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 41 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Motivation
Shortages of the Standard Model (SM)Radiative correction to the Higgs mass term ⇒ hierarchy problemNo cold dark matter (DM) candidate
Supersymmetry (SUSY) and R-parity conservationElegant solution to the hierarchy problemLightest supersymmetric particle (LSP) ⇒ DM candidate
No evidence of superpartners in LHC Run 1 dataPush gluino and squark mass limits up to ≳O(1) TeVElectroweak (EW) production rates are much lower; m∼O(100) GeV EWsuperpartners could hide in Run 1 searches
LHC Run 2 and further searches are promising to directly probean O(100) GeV-scale neutralino-chargino sector
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 41 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Motivation
Shortages of the Standard Model (SM)Radiative correction to the Higgs mass term ⇒ hierarchy problemNo cold dark matter (DM) candidate
Supersymmetry (SUSY) and R-parity conservationElegant solution to the hierarchy problemLightest supersymmetric particle (LSP) ⇒ DM candidate
No evidence of superpartners in LHC Run 1 dataPush gluino and squark mass limits up to ≳O(1) TeV
Electroweak (EW) production rates are much lower; m∼O(100) GeV EWsuperpartners could hide in Run 1 searches
LHC Run 2 and further searches are promising to directly probean O(100) GeV-scale neutralino-chargino sector
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 41 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Motivation
Shortages of the Standard Model (SM)Radiative correction to the Higgs mass term ⇒ hierarchy problemNo cold dark matter (DM) candidate
Supersymmetry (SUSY) and R-parity conservationElegant solution to the hierarchy problemLightest supersymmetric particle (LSP) ⇒ DM candidate
No evidence of superpartners in LHC Run 1 dataPush gluino and squark mass limits up to ≳O(1) TeVElectroweak (EW) production rates are much lower; m∼O(100) GeV EWsuperpartners could hide in Run 1 searches
LHC Run 2 and further searches are promising to directly probean O(100) GeV-scale neutralino-chargino sector
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 41 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Next-to-Minimal Supersymmetric Standard Model (NMSSM)
No explanation for why µ is of the same order of the SUSY breakingscale in the Minimal Supersymmetric Standard Model (MSSM): µ-problem
⇓Introducing a singlet chiral superfield S in the NMSSM: µeff = λvs
Z3-invariant (scale-invariant) superpotential: WMSSM +λSHuHd +κS3/3
Soft breaking terms in the Higgs sector:Vsoft = m2
Hu|Hu|2 +m2
Hd|Hd |2 +m2
S |S|2 +λAλSHuHd +κAκS
3/3+ h.c.
Higgs and higgsino sectors are determined by λ, κ, Aλ, Aκ, µeff, tanβ ≡ vu/vdNeutralino mass matrix for the gauge basis (B, W 0, H0
d , H0u , S):
MN =
M1 0 −g1vd/
p2 g1vu/
p2 0
M2 g2vd/p
2 −g2vu/p
2 00 −µeff −λvu
0 −λvd2κvs
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 42 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Next-to-Minimal Supersymmetric Standard Model (NMSSM)
No explanation for why µ is of the same order of the SUSY breakingscale in the Minimal Supersymmetric Standard Model (MSSM): µ-problem
⇓Introducing a singlet chiral superfield S in the NMSSM: µeff = λvs
Z3-invariant (scale-invariant) superpotential: WMSSM +λSHuHd + κS3/3
Soft breaking terms in the Higgs sector:Vsoft = m2
Hu|Hu|2 +m2
Hd|Hd |2 +m2
S |S|2 +λAλSHuHd + κAκS
3/3+ h.c.
Higgs and higgsino sectors are determined by λ, κ, Aλ, Aκ, µeff, tanβ ≡ vu/vdNeutralino mass matrix for the gauge basis (B, W 0, H0
d , H0u , S):
MN =
M1 0 −g1vd/
p2 g1vu/
p2 0
M2 g2vd/p
2 −g2vu/p
2 00 −µeff −λvu
0 −λvd2κvs
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 42 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Simplified Scenarios for the Neutralino-chargino Sector
Singlino-dominated LSP χ01 ∼ S ⇒ different phenomenology from MSSM’s
Simplified scenarios with split spectraSinglino-Bino Scenario (2κvs < M1≪ M2,µeff): χ0
1 ∼ S, χ02 ∼ B
Observed DM relic density ⇒ mχ01∼O(10) GeV
Very low production rates for χ01 χ
02 and χ0
2 χ02 at the LHC
Singlino-Wino Scenario (2κvs < M2≪ M1,µeff): χ01 ∼ S; χ0
2 , χ±1 ∼ W
Moderate χ02 χ±1 and χ+1 χ−1 production rates
LHC sensitivity is similar to the bino-wino scenario in the MSSM
Singlino-Higgsino Scenario (2κvs < µeff≪ M1, M2): χ01 ∼ S; χ0
2,3, χ±1 ∼ H
Higgsino components of χ01 help satisfy the observed relic density
Lower χ02,3χ
±1 and χ+1 χ−1 rates compared with the singlino-wino scenario
Previous studies on this scenario focused on LHC [Ellwanger, 1309.1665;Kim & Ray, 1405.3700] and IceCube [Enberg et al., 1506.05714] searches
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 43 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Simplified Scenarios for the Neutralino-chargino Sector
Singlino-dominated LSP χ01 ∼ S ⇒ different phenomenology from MSSM’s
Simplified scenarios with split spectraSinglino-Bino Scenario (2κvs < M1≪ M2,µeff): χ0
1 ∼ S, χ02 ∼ B
Observed DM relic density ⇒ mχ01∼O(10) GeV
Very low production rates for χ01 χ
02 and χ0
2 χ02 at the LHC
Singlino-Wino Scenario (2κvs < M2≪ M1,µeff): χ01 ∼ S; χ0
2 , χ±1 ∼ W
Moderate χ02 χ±1 and χ+1 χ−1 production rates
LHC sensitivity is similar to the bino-wino scenario in the MSSM
Singlino-Higgsino Scenario (2κvs < µeff≪ M1, M2): χ01 ∼ S; χ0
2,3, χ±1 ∼ H
Higgsino components of χ01 help satisfy the observed relic density
Lower χ02,3χ
±1 and χ+1 χ−1 rates compared with the singlino-wino scenario
Previous studies on this scenario focused on LHC [Ellwanger, 1309.1665;Kim & Ray, 1405.3700] and IceCube [Enberg et al., 1506.05714] searches
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 43 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Simplified Scenarios for the Neutralino-chargino Sector
Singlino-dominated LSP χ01 ∼ S ⇒ different phenomenology from MSSM’s
Simplified scenarios with split spectraSinglino-Bino Scenario (2κvs < M1≪ M2,µeff): χ0
1 ∼ S, χ02 ∼ B
Observed DM relic density ⇒ mχ01∼O(10) GeV
Very low production rates for χ01 χ
02 and χ0
2 χ02 at the LHC
Singlino-Wino Scenario (2κvs < M2≪ M1,µeff): χ01 ∼ S; χ0
2 , χ±1 ∼ W
Moderate χ02 χ±1 and χ+1 χ−1 production rates
LHC sensitivity is similar to the bino-wino scenario in the MSSM
Singlino-Higgsino Scenario (2κvs < µeff≪ M1, M2): χ01 ∼ S; χ0
2,3, χ±1 ∼ H
Higgsino components of χ01 help satisfy the observed relic density
Lower χ02,3χ
±1 and χ+1 χ−1 rates compared with the singlino-wino scenario
Previous studies on this scenario focused on LHC [Ellwanger, 1309.1665;Kim & Ray, 1405.3700] and IceCube [Enberg et al., 1506.05714] searches
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 43 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Simplified Scenarios for the Neutralino-chargino Sector
Singlino-dominated LSP χ01 ∼ S ⇒ different phenomenology from MSSM’s
Simplified scenarios with split spectraSinglino-Bino Scenario (2κvs < M1≪ M2,µeff): χ0
1 ∼ S, χ02 ∼ B
Observed DM relic density ⇒ mχ01∼O(10) GeV
Very low production rates for χ01 χ
02 and χ0
2 χ02 at the LHC
Singlino-Wino Scenario (2κvs < M2≪ M1,µeff): χ01 ∼ S; χ0
2 , χ±1 ∼ W
Moderate χ02 χ±1 and χ+1 χ−1 production rates
LHC sensitivity is similar to the bino-wino scenario in the MSSM
Singlino-Higgsino Scenario (2κvs < µeff≪ M1, M2): χ01 ∼ S; χ0
2,3, χ±1 ∼ H
Higgsino components of χ01 help satisfy the observed relic density
Lower χ02,3χ
±1 and χ+1 χ−1 rates compared with the singlino-wino scenario
Previous studies on this scenario focused on LHC [Ellwanger, 1309.1665;Kim & Ray, 1405.3700] and IceCube [Enberg et al., 1506.05714] searches
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 43 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Parameter Scan
For the singlino-higgsino scenario, we perform a random parameter scan upon
100 GeV ≤ µeff ≤ 600 GeV −1 TeV ≤ Aκ ≤ 0 100 GeV ≤ Aλ ≤ 10 TeV
1≤ tanβ ≤ 50 0.05≤ λ≤ 0.7 0.05≤ κ/λ≤ 0.4
The condition κ/λ≤ 0.4 is imposed for ensuring χ01 ∼ S
Set M1 = M2 = 2 TeV and other dimensional parameters to be 5 TeV
NMSSMTools 4.6 and micrOMEGAs 3 are employed for calculating mass spectra,relic density, and other observable. The following constraints are imposed.
DM relic density: Ωχ01h2 < 0.131
Higgs: an SM-like Higgs with mh = 122− 128 GeV; current Higgs boundsLEP bounds: mχ±1 > 103.5 GeV; Γ inv
Z < 2 MeV
Muon g − 2: within the 3σ deviation −5.62× 10−11 < aNMSSMµ
< 5.54× 10−9
B physics bounds: 1.7× 10−9 < BR(Bs → µ+µ−)< 4.5× 10−9;0.85× 10−4 < BR(B+→ τ+ν)< 2.89× 10−4; 2.99× 10−4 < BR(Bs → Xsγ)< 3.87× 10−4
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 44 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Parameter Scan
For the singlino-higgsino scenario, we perform a random parameter scan upon
100 GeV ≤ µeff ≤ 600 GeV −1 TeV ≤ Aκ ≤ 0 100 GeV ≤ Aλ ≤ 10 TeV
1≤ tanβ ≤ 50 0.05≤ λ≤ 0.7 0.05≤ κ/λ≤ 0.4
The condition κ/λ≤ 0.4 is imposed for ensuring χ01 ∼ S
Set M1 = M2 = 2 TeV and other dimensional parameters to be 5 TeV
NMSSMTools 4.6 and micrOMEGAs 3 are employed for calculating mass spectra,relic density, and other observable. The following constraints are imposed.
DM relic density: Ωχ01h2 < 0.131
Higgs: an SM-like Higgs with mh = 122− 128 GeV; current Higgs boundsLEP bounds: mχ±1 > 103.5 GeV; Γ inv
Z < 2 MeV
Muon g − 2: within the 3σ deviation −5.62× 10−11 < aNMSSMµ
< 5.54× 10−9
B physics bounds: 1.7× 10−9 < BR(Bs → µ+µ−)< 4.5× 10−9;0.85× 10−4 < BR(B+→ τ+ν)< 2.89× 10−4; 2.99× 10−4 < BR(Bs → Xsγ)< 3.87× 10−4
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 44 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Relic Density Ωχ01h2 and Singlino Component |N15|2
Ω h
2
mχ~
10 (GeV)
Planck
10-5
10-4
10-3
10-2
10-1
100
0 50 100 150 200 250 300 350 400 450 500
N1
52
mχ~
10 (GeV)
0.5
0.55
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
10 100 1000
Z boson resonanceSM-like Higgs resonance
All points pass the above constraints; red points for 0.107< Ωχ01h2 < 0.131
mχ01∼ 45 GeV and ∼ 60 GeV: resonance enhancements of the Z boson and
the SM-like Higgs boson for χ01 χ
01 annihilation
mχ01≳ 70 GeV: smaller |N15|2 and sizable Higgsino components
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 45 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Decay Patterns of χ02 and χ0
3B
ran
ch
ing
ra
tio
mχ~
20 (GeV) − mχ
~
10 (GeV)
Br(χ~
20 → χ
~
10 Z)
Br(χ~
20 → χ
~
10 h1)
Br(χ~
20 → χ
~
10 h2)
Br(χ~
20 → χ
~
10 a1)
0.2
0.4
0.6
0.8
1
1.2
50 100 150 200 250 300 350 400 450 500
m h1 ≥ 122
m h1 < 122
χ02 decay pattern
Bra
nch
ing
ra
tio
mχ~
30 (GeV) − mχ
~
10 (GeV)
Br(χ~
30 → χ
~
10 Z)
Br(χ~
30 → χ
~
10 h1)
Br(χ~
30 → χ
~
10 h2)
Br(χ~
30 → χ
~
10 a1)
0.2
0.4
0.6
0.8
1
1.2
50 100 150 200 250 300 350 400 450 500
m h1 ≥ 122
m h1 < 122
χ03 decay pattern
χ02 decay: χ0
2 → χ01 Z is typically dominant
χ03 decay: χ0
3 → χ01 Z , χ0
3 → χ01 h1, and χ0
3 → χ01 h2 are significant
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 46 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Benchmark Points
BP1 BP2 BP3λ, κ 0.091, 0.016 0.270, 0.100 0.368, 0.144
tanβ , µeff (GeV) 39.6, 163.3 35.1, 121.3 35.6, 121.0Aκ (GeV), Aλ (TeV) −35.9, 8.94 −173.4, 3.79 −8.77, 4.43
mχ01
(GeV) 59.6 77.0 71.7mχ0
2, mχ0
3, mχ±1 (GeV) 169, 173, 170 134, 146, 126 137, 160, 126
mh1, mh2
, ma1(GeV) 46.0, 126, 55.8 23.0, 125, 153 95.3, 125, 38.7
|N13|2 + |N14|2, |N15|2 1.3%, 98.7% 33.2%, 66.8% 43.5%, 56.4%Ωχ0
1h2 0.120 0.059 0.067
BR(χ02 → χ0
1 X ) Z 98.7% h1 84.4%, qq 10.6%a1 98.6%
ℓ+ℓ− 3%, vℓ vℓ 3%
BR(χ03 → χ0
1 X )Z 97.1%
h1 100% a1 73.2%, qq 14%a1 2.7% ℓ+ℓ− 2%, vℓ vℓ 4%
BR(h1/a1→ bb/τ+τ−) / h1→ bb 91.8% a1→ bb 91.8%h1→ τ+τ− 7.3% a1→ τ+τ− 7.7%
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 47 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
LHC Searches
χ±1
χ02,3
W±
Z
p
p
ℓ′±
νℓ′/νℓ′
χ01
χ01
ℓ−
ℓ+
3ℓ+ /ET signature
χ−1
χ+1
W−
W+
p
p
ℓ′−
νℓ′
χ0
1
χ0
1
νℓ
ℓ+
2ℓ+ /ET signature
We consider pp→ χ02,3χ
±1 and pp→ χ+1 χ−1 production at the LHC for the
survived parameter points in the singlino-higgsino scenarioMC simulation: MadGraph 5 + PYTHIA 6 + Delphes 3
↓MLM matching ATLAS setup
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 48 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
3ℓ+ /ET Channelevents
/ (
GeV
fb
-1 )
LHC , √s = 14 TeV, 3 leptons
10-4
10-3
10-2
10-1
100
101
Fra
ction
mSFOS (GeV)
W Z
Z Z
BP1
BP2
BP3
0
0.2
0.4
0.6
0 50 100 150 200 250 300
events
/ (
GeV
fb
-1 )
LHC , √s = 14 TeV, 3 leptons
10-4
10-3
10-2
10-1
100
101
Fra
ction
mT (GeV)
W Z
Z Z
BP1
BP2
BP3
0
0.1
0.2
0 50 100 150 200 250 300
Main backgrounds: W Z + jets and Z Z + jets productionSelection cuts at ps = 14 TeV: exact 3 charged leptons ℓ (ℓ= e,µ) withpT > 20 GeV and |η|< 2.5; no b-jet with pT > 30 GeV and |η|< 2.5;|mSFOS −mZ |< 10 GeV; /ET > 50 or 100 GeV; mT > 100 GeV
(mSFOS is the invariant mass of a same-flavor opposite-sign (SFOS) lepton pair. Transversemass mT ≡q
2(pℓT /ET − pℓT · /pT) with ℓ the one not forming the SFOS lepton pair.)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 49 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
2ℓ+ /ET Channelevents
/ (
GeV
fb
-1 )
LHC , √s = 14 TeV, 2 leptons
10-3
10-2
10-1
100
101
Fra
ction
mSFOS (GeV)
W Z
W W
Z Z
tt−
BP1
BP2
BP3
0
0.2
0.4
0.6
0 50 100 150 200
events
/ (
GeV
fb
-1 )
LHC , √s = 14 TeV, 2 leptons
10-3
10-2
10-1
100
101
102
103
Fra
ction
mT2 (GeV)
W Z
W W
Z Z
tt−
BP1
BP2
BP3
0.2
0.4
0 50 100 150 200 250 300
Main backgrounds: t t + jets, WW + jets, W Z + jets, and Z Z + jets productionSelection cuts at ps = 14 TeV: exact 2 opposite-sign charged leptons withpℓ1
T > 30 GeV, pℓ2T > 20 GeV, and |η|< 2.5; |mSFOS −mZ |> 10 GeV;
no jet with pT > 30 GeV and |η|< 2.5; mT2 > 90, 120, or 150 GeV
(Stransverse mass mT2 ≡ minp1
T+p2T=/pT
max[mT(pℓ1T ,p1
T), mT(pℓ2T ,p2
T)].)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 50 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Cut Flows
3ℓ+ /ET channel at ps = 14 TeV
W Z Z Z BP1 BP2 BP3σ σ σ S σ S σ S
Basic cuts 105 17.3 6.39 9.77 0.021 0.033 0.060 0.095/ET > 50 GeV 37.2 1.51 4.11 10.9 0.008 0.023 0.034 0.094mT > 100 GeV 1.22 0.06 1.60 16.3 0.004 0.058 0.014 0.212
2ℓ+ /ET channel at ps = 14 TeV
W Z Z Z WW t t BP1 BP2 BP3σ σ σ σ σ S σ S σ S
Basic cuts 88.8 22.3 1798 8930 16.8 2.79 9.75 1.62 12.7 2.12Jet veto 35.8 7.25 848 253 8.23 4.20 5.42 2.77 6.86 3.50
mT2 > 90 GeV 0.24 0.32 0.48 0.98 0.58 6.21 0.05 0.61 0.13 1.48
(σ in fb; S ≡ S/p
B + S calculated with an integrated luminosity of 300 fb−1)
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 51 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
(Expected) Exclusion at 95% CLm
χ~20 (
Ge
V)
mχ~10 (GeV)
LHC, three leptons
m χ~ 20=m χ~ 1
0+ m Z
√s = 14 TeV, 300 fb-1
√s = 13 TeV, 30 fb-1
√s = 8 TeV, 20 fb-1
100
200
300
400
500
600
0 50 100 150 200 250 300 350 400
3ℓ+ /ET channel
mχ~
20 (
Ge
V)
mχ~10 (GeV)
LHC, two leptons
m χ~ 20=m χ~ 1
0+ m Z
√s = 14 TeV, 300 fb-1
√s = 13 TeV, 30 fb-1
√s = 8 TeV, 20 fb-1
100
200
300
400
500
600
0 50 100 150 200 250 300 350 400
2ℓ+ /ET channel
Red/blue/green points: ps = 8/13/14 TeV with 20/30/300 fb−1 data8 TeV results are recasted from Run 1 analyses [ATLAS, 1402.7029, 1403.5294]
3ℓ+ /ET channel at 14 TeV: up to mχ02 ,χ±1 ∼ 420 GeV
2ℓ+ /ET channel at 14 TeV: up to mχ02 ,χ±1 ∼ 500 GeV
Some points with mχ02−mχ0
1≲ mZ are hard to probe due to soft final states
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 52 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Spin-Independent (SI) DM-Nucleus Scattering
σS
Ip (
cm
2)
mχ~
10 (GeV)
XENON1T
LUX
10-52
10-50
10-48
10-46
10-44
10-42
10-40
10-38
10 100 1000
ξσS
Ip (
cm
2)
mχ~10 (GeV)
XENON1T
LUX
10-52
10-50
10-48
10-46
10-44
10-42
10-40
10-38
10 100 1000
In the singlino-higgsino scenario, the SI DM-nuclei scattering is mediated by h1 and h2
Resonance enhancement for freeze-out⇓
Small higgsino components in χ01⇓
Small scattering cross section
90% CL exclusion limits: LUX [1310.8214],XENON1T expected for 2 t · yr [1512.07501]
Red/blue/green points: 8/13/14 TeV LHC⊡ BP1 · BP2 · BP3
Define ξ=min(1,Ωχ01h2/0.107) to take
into account the possibility that χ01 just
contributes a fraction of dark matter −→
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 53 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Spin-Independent (SI) DM-Nucleus Scattering
σS
Ip (
cm
2)
mχ~
10 (GeV)
XENON1T
LUX
10-52
10-50
10-48
10-46
10-44
10-42
10-40
10-38
10 100 1000
ξσS
Ip (
cm
2)
mχ~10 (GeV)
XENON1T
LUX
10-52
10-50
10-48
10-46
10-44
10-42
10-40
10-38
10 100 1000
In the singlino-higgsino scenario, the SI DM-nuclei scattering is mediated by h1 and h2
Resonance enhancement for freeze-out⇓
Small higgsino components in χ01⇓
Small scattering cross section
90% CL exclusion limits: LUX [1310.8214],XENON1T expected for 2 t · yr [1512.07501]
Red/blue/green points: 8/13/14 TeV LHC⊡ BP1 · BP2 · BP3
Define ξ=min(1,Ωχ01h2/0.107) to take
into account the possibility that χ01 just
contributes a fraction of dark matter −→Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 53 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Spin-Dependent (SD) DM-nucleus Scattering
σS
Dp (
cm
2)
mχ~
10 (GeV)
IceCube
PICO-2L
PICO-60
LZ
10-44
10-43
10-42
10-41
10-40
10-39
10-38
10 100 1000
ξσS
Dp (
cm
2)
mχ~10 (GeV)
IceCube
PICO-2L
PICO-60
LZ
10-44
10-43
10-42
10-41
10-40
10-39
10-38
10 100 1000
The Z-mediated SD DM-nuclei scatteringcross section σSD is typically larger thanσSI by ∼ 2− 6 orders of magnitude, but theexperimental constraints are quite weak
90% CL exclusion limits:PICO [1503.00008, 1510.07754]
LZ expected for 5600 t · day [1509.02910]
IceCube search for νµ from χ01 χ
01 → t t
in the center of the Sun [1601.00653]
Introducing ξ will weaken the constraints −→
Red/blue/green points: 8/13/14 TeV LHC⊡ BP1 · BP2 · BP3
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 54 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
DM Annihilation
Annih
ilation b
ranchin
g fra
ction
mχ~
10
W+ W
-
Z Z
tt−
bb-
Z h1
Z h2
a1 h1
a1 h2
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250 300 350 400 450 500
⟨σa
nn v
⟩ (c
m3 s
-1)
mχ~
10 (GeV)
-
-
Fermi bb
CTA bb
10-34
10-32
10-30
10-28
10-26
10-24
10 100 1000
p-wave annihilation is important at the freeze-out epoch, but becomes negligible for today’snonrelativistic DM relevant to indirect detection
Nonrelativistic χ01 χ
01 annihilation
mχ01≲ mt : χ0
1 χ01 → bb or a1h1 dominant
with ⟨σannv⟩ ∼O(10−31 − 10−27) cm3/s
mχ01≳ mt : χ0
1 χ01 → t t dominant with
canonical ⟨σannv⟩ ∼O(10−26) cm3/s
95% CL exclusion limits for χ01 χ
01 → bb:
Fermi-LAT γ-ray observation of dwarf galaxiesfor 6 years [1503.02641], expected CTA γ-rayobservation of GC vicinities for 100 h [1208.5356]
Red/blue/green points: 8/13/14 TeV LHC⊡ BP1 · BP2 · BP3
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 55 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Indirect Detection: the ξ2 Factor
Red/blue/green points: 8/13/14 TeV LHC⊡ BP1 · BP2 · BP3
⟨σa
nn v
⟩ (c
m3 s
-1)
mχ~
10 (GeV)
-
-
Fermi bb
CTA bb
10-34
10-32
10-30
10-28
10-26
10-24
10 100 1000
Without the ξ2 factorξ2
⟨σa
nn v
⟩ (c
m3 s
-1)
mχ~10 (GeV)
-
-
Fermi bb
CTA bb
10-34
10-32
10-30
10-28
10-26
10-24
10 100 1000
With the ξ2 factor
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 56 / 57
Z′-portal DM τ-portal DM Stop Searches and DM Coannihilation Singlino-Higgsino DM Homework
Homework
1 Calculate the Z ′ partial widths Γ (Z ′→ qq) and Γ (Z ′→ χχ) for theZ ′-portal Lagrangians in Page 7(Results can be found in arXiv:1503.02931)
2 Draw Feynman diagrams for DM annihilation into τ+τ− in the MFDM andRSDM models described in Page 13
3 In the low velocity limit, derive the DM annihilation cross sections intoτ+τ−, ⟨σannv⟩, in Page 14 from the τ-portal Lagrangians in Page 13
4 Draw Feynman diagrams for stop decay processes t1→ tχ01 , bW χ0
1 , cχ01 ,
f f ′bχ01 , bχ±1 , and bτ+1ντ
5 Derive the neutralino mass matrix MN in Page 42 from the NMSSMsuperpotential and soft breaking terms
Zhao-Huan Yu (Melbourne) Dark Matter Searches at Hadron Colliders July 2017 57 / 57
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