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Casting Light on Dark Matter?

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

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Casting Light on Dark Matter?

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  1. Casting Light on Dark Matter? John ELLIS, King’s College London & CERN

  2. 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?

  3. Unofficial Combination of Higgs Search Data from March 6th Is this the Higgs Boson? No Higgs here! No Higgs here!

  4. It Walks and Quacks like a Higgs • Do couplings scale ~ mass? With scale = v? • Red line = SM, dashed line = best fit Global fit JE & Tevong You, arXiv:1303.3879

  5. 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

  6. 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

  7. Relic Density Calculation • Freeze-out from thermal equilibrium • Typical annihilation cross section ~ 3 ✕ 10-26 cm2 • Lower if coannihilation with related particles

  8. Supersymmetric Signature @ LHC Look for missing transverse energy carried away by dark matter particles

  9. Searches ~ 5/fb @ 8 TeV Supersymmetry Searches @ LHC “Classic” missing-energy search Multiple searches including b, leptons

  10. Global Fit to Supersymmetric Model 2 5 Scan of CMSSM Impacts of searches with full 2012 data Update of Buchmueller et al: arXiv:1207.3715 p-value of simple models < 10%

  11. Global Fit to Supersymmetric Model 1 5 Gluino mass CMSSM Update of Buchmueller, JE et al: arXiv:1207.3715 Favoured values of gluino mass significantly above pre-LHC, > 1.5 TeV

  12. Cosmological Inflation in Light of Planck • A scalar in the sky? AWess-Zumino model?

  13. 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

  14. Higgs Inflation: a Single Scalar? Bezrukov & Shaposhnikov, arXiv:0710.3755 • Standard Model with non-minimal coupling to gravity: • Potential similar to Starobinsky, but not identical BUT: needs MH > 127 GeV ≠ LHC?

  15. Supersymmetric Inflation in Light of Planck • Supersymmetric Wess-Zumino (WZ) model consistent with Planck data ϕ4 ϕ2 ϕ WZ ϕ2/3 Croon, JE, Mavromatos: arXiv:1303.6253

  16. 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 ~ – MP4 • 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

  17. No-Scale Supergravity Inflation • Good inflation for Looks like R2 model JE, Nanopoulos & Olive, arXiv:1305.1247, 1307.3537

  18. Strategies for Detecting Supersymmetric Dark Matter Scattering on nucleus in laboratory χ + A χ + A Annihilation in core of Sun or Earth χ – χν + … μ + … Annihilation in galactic centre, dwarf galaxies χ – χγ + …? Annihilation in galactic halo χ – χ positrons, antiprotons, …?

  19. Direct Searches for Dark Matter New CDMS result Best limit: XENON100 with 225 days of data Confusion at low WIMP masses? Aprile et al.

  20. Global Fit to Supersymmetric Model 2 5 Spin-independent Dark matter scattering --- 1/fb ___ 5/fb Excluded by XENON100 Excluded by LHC Buchmueller, JE et al: arXiv:1207.3715 Favoured values of dark matter scattering cross section significantly below XENON100

  21. Strategies for Detecting Supersymmetric Dark Matter Scattering on nucleus in laboratory χ + A χ + A Annihilation in core of Sun or Earth χ – χν + … μ + … Annihilation in galactic centre, dwarf galaxies χ – χγ + …? Annihilation in galactic halo χ – χ positrons, antiprotons, …?

  22. Neutralino Annihilation Rates In some supersymmetric models may be much smaller than order-of-magnitude estimate JE, Olive & Spanos, arXiv:1106.0768

  23. Annihilation Branching Fractions Vary in different regions of parameter space Must be modelled correctly JE, Olive & Spanos, arXiv:1106.0768

  24. Fermi γ line@ 130 GeV? • BUT: Fermi Collaboration also sees bump in control sample of γ’s from Earth’s limb • Presumably a systematic effect Weniger analysis claimed “4 σ” (3 σ with look-elsewhere effect)

  25. AMS-02 on International Space Station (ISS)

  26. Positron Fraction Rising with E Dark Matter? Galactic cosmic rays? Local sources?

  27. 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

  28. 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

  29. Galactic Cosmic Rays Alone? • Rising positron fraction compatible with model-independent bound on secondary e+ Blum, Katz& Waxman, arXiv:1305.1324

  30. Galactic Cosmic Rays Alone? • Can fit positron data with modified cosmic-ray model • BUT: problems with e-, p _ JE, Olive & Spanos, in preparation

  31. 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

  32. The LHC may cast light on dark matter… … dark matter experiments may cast light on fundamental questions in particle physics

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