Overview of Supersymmetry and
Dark Matter
John Ellis
King’s College London
(& CERN)
Strange Recipe for a Universe
The ‘Standard Model’ of the Universe
indicated by astrophysics and cosmology
Relic Density Calculation
• Freeze-out from thermal equilibrium
• Typical annihilation cross section ~ 3 ✕ 10-26 cm2
• Lower if coannihilation with related particles
300,000
years
Formation
of atoms
3
minutes
Formation
of nuclei
1 microsecond
Appearance
1 pico- of dark matter?
second
Formation
of protons
& neutrons
Appearance
Appearance of mass?
of matter?
Classic Dark Matter Signature
Missing transverse energy
carried away by dark matter particles
What else is there?
Supersymmetry
• Successful prediction for Higgs mass
– Should be < 130 GeV in simple models
• Successful predictions for Higgs couplings
– Should be within few % of SM values
• Could explain the dark matter
• Naturalness, GUTs, string, … (???)
Higgs Bosons in Supersymmetry
• Need 2 complex Higgs doublets
(cancel anomalies, form of SUSY couplings)
• 8 – 3 = 5 physical Higgs bosons
Scalars h, H; pseudoscalar A; charged H±
• Lightest Higgs < MZ at tree level:
• Important radiative corrections to mass:
ΔMH|TH ~ 1.5 GeV
MSSM Higgs Masses & Couplings
Lightest Higgs mass
up to ~ 130 GeV
Heavy Higgs masses
quite close
Consistent
With LHC
Supersymmetric Higgs Couplings
• Very similar to those in the SM
• Present data do not constrain
supersymmetric models
H to WW
• Need future collider to distinguish
Where May SUSY be Hiding?
Excluded because
stau or stop LSP
Stop
coannihilation
strip
Excluded by ATLAS
Jest + MET search
Excluded by
b  s γ, Bs  μ+μRelic density constraint,
assuming
neutralino LSP
JE, Olive & Zheng: arXiv:1404.5571
Stau
coannihilation
strip
Data
• Electroweak precision
observables
• Flavour physics
observables
Deviation from Standard Model:
• gμ - 2
Supersymmetry at low scale, or …?
• Higgs mass
• Dark matter
M = 125.6 ± 0.3 ± 1.5 GeV
• LHC
H
MasterCode: O.Buchmueller, JE et al.
O. Buchmueller, R. Cavanaugh, M. Citron, A. De Roeck, M.J. Dolan, J.E., H. Flacher, S. Heinemeyer, G. Isidori,
J. Marrouche, D. Martinez Santos, S. Nakach, K.A. Olive, S. Rogerson, F.J. Ronga, K.J. de Vries, G. Weiglein
Search with ~ 20/fb @ 8 TeV
2012
20/fb
Scan of CMSSM
Buchmueller, JE et al: arXiv:1312.5250
p-value of simple models ~ 5% (also SM)
LHC Reach for Supersymmetry
K. De Vries
(MasterCode)
Confronted with likelihood analysis of CMSSM
20121
Squark mass
520/fb
Reach of LHC at
High luminosity
CMSSM
Buchmueller, JE et al: arXiv:1312.5250
Favoured values of squark mass also significantly
above pre-LHC, > 1.6 TeV
20121
Gluino mass
520/fb
Reach of LHC at
CMSSM High luminosity
CMSSM
Buchmueller, JE et al: arXiv:1312.5250
Favoured values of gluino mass significantly
above pre-LHC, > 1.8 TeV
Proton-Proton Colliders:
Luminosity and Energy
• Future runs of the LHC:
– Run 2: 30/fb @ 13/14 TeV
– Run 3: 300/fb @ 14 TeV
• HL-LHC: 3000/fb @ 14 TeV?
(proposed in CERN’s medium-term plan)
• HE-LHC: 3000/fb @ 33 TeV??
(high-field magnets in the LHC tunnel)
• VHE-LHC: 3000/fb @ 100 TeV??
(high-field magnets in 80/100 km tunnel)
Exploring the Stau Coannihilation Strip
• Disappearing tracks, missing-energy + jets,
massive metastable charged particles
Present
sensitivity
Desai, JE, Luo & Marrouche: arXiv:1404.5061
Present
sensitivity
Prospective sensitivity of LHC Run II
What Parts of High-Mass
Parameter Space are Allowed?
1 26
124
621
122
1000
3.2e−09
90−e2.3
2.3
90−e
120
.3
90−e2
100
0.0
O. Buchmueller, JE, K. Olive et al.
621
12 5
2000
m0 (GeV)
3.2e−09
m1/2 (GeV)
3000
3.2e−09
90−
e2. 3
3.2e−09
• Extends to m1/2 ~ 4 TeV
• Neutralino has Higgsino
mixture
• Truncated by mh
127
421
– A0 ~ 0, large m0/m1/2
128
521
• Imposing dark matter
density constraint
• Focus-point strip:
tan b = 10, A0 = 0 , µ > 0
4000
1.0×104
What Parts of High-Mass
Parameter Space are Allowed?
8
12
128
621
126
127
621 125
127
128
721
128
125
125
1
127 26
126
126
124
1000
122
126
130
LHC 300
130
LHC 8 TeV
126
132
125
124
127 128
128
128
LHC 3000
128
125
125621
125421
126
821 128
621
128
2000
821
126
126
7
12
132
m1/2 (GeV)
130
421
O. Buchmueller, JE, K. Olive et al.
7
12
3000
125
• Extends to m1/2 ~ 13 TeV
• Very small mass
difference: mstop – mχ
• mh very uncertain
132
130
– A0 ~ 3 m0, large m0/m1/2
HE-LHC
1 28
• Imposing dark matter
density constraint
• Stop coannihilation
strip:
tan b = 10, A0 = 2.3m0, µ > 0
4000
100
0.0
m0 (GeV)
1.0×104
Exploring the Stop Coannihilation Strip
• Extends close to boundary of stop LSP wedge
Sensitivity of
LHC Run II
Present
bounds
• Extends to masses far beyond current limits
JE, Olive & Zheng: arXiv:1404.5571
Exploring the Stop Coannihilation Strip
• Extended by Sommerfeld effects on annihilations
• Compatible with LHC measurement of mh
• May extend to mχ = mstop ~ 6500 GeV
JE, Olive & Zheng: arXiv:1404.5571
Exploring the Stop Coannihilation Strip
• Present limits extend to mstop ~250 GeV
• Future LHC runs should reach mχ=mstop~500 GeV
• Unfinished business for FCC-hh?
JE, Olive & Zheng: arXiv:1404.5571
Direct Dark Matter Searches
• Compilation of present and future sensitivities
Range calculated
along stop strip
Neutrino
“wall”
JE, Olive & Zheng