John Ellis

King’s College London

(& CERN)

Overview of Supersymmetry and Dark Matter

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

3

minutes

1 micro-

second

1 pico-

second

Formation

of atoms

Formation

of nuclei

Formation

of protons

& neutronsAppearance

of mass?

Appearance

of dark matter?

Appearance

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 bosonsScalars 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

• Very similar to those in the SM• Present data do not constrain

supersymmetric models

• Need future collider to distinguish

Supersymmetric Higgs Couplings

H to WW

Where May SUSY be Hiding?

Excluded by

b s γ, Bs μ+μ-

Relic density constraint,

assuming

neutralino LSP

JE, Olive & Zheng: arXiv:1404.5571

Stop

coannihilation

strip

Stau

coannihilation

strip

Excluded by ATLAS

Jest + MET search

Excluded because

stau or stop LSP

Data

• Electroweak precision observables

• Flavour physics observables

• gμ - 2

• Higgs mass• Dark matter• LHC

MasterCode: O.Buchmueller, JE et al.

Deviation from Standard Model:

Supersymmetry at low scale, or …?

MH = 125.6 ± 0.3 ± 1.5 GeV

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

p-value of simple models ~ 5% (also SM)

2012 20/fb

Scan of CMSSM

Buchmueller, JE et al: arXiv:1312.5250

Confronted with likelihood analysis of CMSSM

LHC Reach for Supersymmetry

K. De Vries

(MasterCode)

51 20/fb2012

Squark mass

CMSSM

Favoured values of squark mass also significantly

above pre-LHC, > 1.6 TeV

Buchmueller, JE et al: arXiv:1312.5250

Reach of LHC at

High luminosity

51 20/fb2012

CMSSM

Favoured values of gluino mass significantly

above pre-LHC, > 1.8 TeV

Buchmueller, JE et al: arXiv:1312.5250

Gluino mass

CMSSM

Reach of LHC at

High luminosity

• 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)

Proton-Proton Colliders:Luminosity and Energy

Exploring the Stau Coannihilation Strip

• Disappearing tracks, missing-energy + jets, massive metastable charged particles

Desai, JE, Luo & Marrouche: arXiv:1404.5061

Present

sensitivity

Present

sensitivity

Prospective sensitivity of LHC Run II

What Parts of High-Mass Parameter Space are Allowed?

• Imposing dark matter density constraint

• Focus-point strip:– A0 ~ 0, large m0/m1/2

• Extends to m1/2 ~ 4 TeV

• Neutralino has Higgsino mixture

• Truncated by mh

O. Buchmueller, JE, K. Olive et al.

What Parts of High-Mass Parameter Space are Allowed?

• Imposing dark matter density constraint

• Stop coannihilation strip:– A0 ~ 3 m0, large m0/m1/2

• Extends to m1/2 ~ 13 TeV

• Very small mass difference: mstop – mχ

• mh very uncertain

HE-LHC

LHC 3000

LHC 300

LHC 8 TeV

O. Buchmueller, JE, K. Olive et al.

Exploring the Stop Coannihilation Strip

• Extends close to boundary of stop LSP wedge

• Extends to masses far beyond current limitsJE, Olive & Zheng: arXiv:1404.5571

Present

bounds

Sensitivity of

LHC Run II

Exploring the Stop Coannihilation Strip

• Extended by Sommerfeld effects on annihilations

• Compatible with LHC measurement of mh

• May extend to mχ = mstop ~ 6500 GeVJE, 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

JE, Olive & Zheng

Neutrino

“wall”