Casting Light on Dark Matter?

John ELLIS,

King’s College London & CERN

The Current Context• Three major new experimental results• The discovery of a Higgs boson @ LHC

– Constraints on models of dark matter– But no evidence of dark matter particles

• Planck satellite data– Consistent with ΛCDM model– Constraints on inflationary models

• First data from the AMS-02 experiment– Rising positron fraction– Astrophysics or dark matter annihilations?

Unofficial Combination of Higgs Search Data from March 6th

Is this theHiggs Boson?

No Higgs here!NoHiggshere!

It Walks and Quacks like a Higgs

• Do couplings scale ~ mass? With scale = v?

• Red line = SM, dashed line = best fitJE & Tevong You, arXiv:1303.3879

Globalfit

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

• Naturalness, GUTs, string, …

• Could explain the dark matter

Lightest Sparticle as Dark Matter

• Stable in many models because of conservation of R parity:

R = (-1) 2S –L + 3B

where S = spin, L = lepton #, B = baryon #

• Particles have R = +1, sparticles R = -1:Sparticles produced in pairs

Heavier sparticles lighter sparticles

• Lightest supersymmetric particle (LSP) stable

• Present in Universe today as relic from Big Bang

Fayet

Relic Density Calculation• Freeze-out from thermal equilibrium

• Typical annihilation cross section ~ 3 ✕ 10-26 cm2

• Lower if coannihilation with related particles

Supersymmetric Signature @ LHC

Look for missing transverse energy

carried away by dark matter particles

“Classic” missing-energy search

Searches ~ 5/fb @ 8 TeVSupersymmetry Searches @ LHC

Multiple searches including b, leptons

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p-value of simple models < 10%

2

Scan of CMSSM

Impacts of searcheswith full 2012 data

Update of Buchmueller et al: arXiv:1207.3715

Global Fit to Supersymmetric Model

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Favoured values of gluino mass significantlyabove pre-LHC, > 1.5 TeV

Gluino mass

Update of Buchmueller, JE et al: arXiv:1207.3715

CMSSM

Global Fit to Supersymmetric Model

Cosmological Inflation in Light of Planck

• A scalar in the sky? A Wess-Zumino model?

Inflationary Models in Light of Planck

• Planck CMB observations consistent with inflation

• Tilted scalar perturbation spectrum:

ns = 0.9585 ± 0.070

• BUT strengthen upper limit on tensor perturbations: r < 0.10

• Challenge for simple

inflationary models

• Starobinsky R2 to rescue?

• Supersymmetry to rescue? Croon, JE & Mavromatos: arXiv:1303.6253

Higgs Inflation: a Single Scalar?

• Standard Model with non-minimal coupling to gravity:

• Potential similar to Starobinsky, but not identical

Bezrukov & Shaposhnikov, arXiv:0710.3755

BUT: needs MH > 127 GeV ≠ LHC?

Supersymmetric Inflation in Light of Planck

• Supersymmetric Wess-Zumino (WZ) model consistent with Planck data

ϕ4

ϕ2

ϕϕ2/3

Croon, JE, Mavromatos: arXiv:1303.6253

WZ

No-Scale Supergravity Inflation

• The only good symmetry is a local symmetry

• Early Universe cosmology needs gravity

• Supersymmetry + gravity = Supergravity

• BUT: potentials in generic supergravity models have potential ‘holes’ with depths ~ – MP

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• Exception: no-scale supergravity

• Appears in compactifications of string

• Flat directions, scalar potential ~ global model + controlled corrections JE, Nanopoulos & Olive, arXiv:1305.1247, 1307.3537

No-Scale Supergravity Inflation

• Good inflation for

Looks like R2 model

JE, Nanopoulos & Olive, arXiv:1305.1247, 1307.3537

Strategies for Detecting Supersymmetric Dark Matter

• Scattering on nucleus in laboratoryχ + A χ + A

• Annihilation in core of Sun or Earthχ – χ ν + … μ + …

• Annihilation in galactic centre, dwarf galaxiesχ – χ γ + …?

• Annihilation in galactic haloχ – χ positrons, antiprotons, …?

Best limit: XENON100 with 225 days of data

Confusion at low WIMP masses?Aprile et al.

Direct Searches for Dark MatterNew CDMS result

Favoured values of dark matter scatteringcross section significantly below XENON100

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Buchmueller, JE et al: arXiv:1207.3715

Spin-independentDark matter scattering

Excluded byXENON100

Excluded by LHC

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Global Fit to Supersymmetric Model

Strategies for Detecting Supersymmetric Dark Matter

• Scattering on nucleus in laboratoryχ + A χ + A

• Annihilation in core of Sun or Earthχ – χ ν + … μ + …

• Annihilation in galactic centre, dwarf galaxiesχ – χ γ + …?

• Annihilation in galactic haloχ – χ positrons, antiprotons, …?

Neutralino Annihilation Rates

In somesupersymmetric models

may be much smaller than

order-of-magnitudeestimate

JE, Olive & Spanos, arXiv:1106.0768

Annihilation Branching FractionsVary in different regions of parameter space

JE, Olive & Spanos, arXiv:1106.0768 Must be modelled correctly

• BUT: Fermi Collaboration also sees bump in control sample of γ’s from Earth’s limb

• Presumably a systematic effect

Fermi γ line@ 130 GeV?

Weniger analysisclaimed “4 σ”

(3 σ with look-elsewhere effect)

AMS-02 on International Space Station (ISS)

Positron Fraction Rising with E

Dark Matter? Galactic cosmic rays? Local sources?

Dark Matter Fit to AMS Positron Data

• Can find good fit: χ2 ~ 18 with annihilation to τ+τ- by modifying cosmic ray parameters

JE, Olive & Spanos, in preparation

Dark Matter Fit to AMS Positron Data

• BUT: very large annihilation cross section

~ 3 ✕ 10-23 cm2 >> required for relic density• OR: very large boost from halo density

fluctuation(s) JE, Olive & Spanos, in preparation

Galactic Cosmic Rays Alone?

• Rising positron fraction compatible with model-independent bound on secondary e+

Blum, Katz& Waxman, arXiv:1305.1324

Galactic Cosmic Rays Alone?

• Can fit positron data with modified cosmic-ray model

• BUT: problems with e-, p_

JE, Olive & Spanos, in preparation

Assume Local Source: Constrain any extra Dark Matter Contribution

• Dark Matter annihilation could give feature above otherwise smooth distribution

Bergstrom et al, arXiv::1306.3983

The LHC may cast light on dark matter…

… dark matter experiments may cast light on

fundamental questions in particle physics