Casting Light on Dark Matter?

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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 - PowerPoint PPT Presentation

Transcript of Casting Light on Dark Matter?

  • Casting Light on Dark Matter?John ELLIS,Kings College London & CERN

  • The Current ContextThree major new experimental resultsThe discovery of a Higgs boson @ LHCConstraints on models of dark matterBut no evidence of dark matter particlesPlanck satellite dataConsistent with CDM modelConstraints on inflationary modelsFirst data from the AMS-02 experimentRising positron fractionAstrophysics or dark matter annihilations?

  • Unofficial Combination of Higgs Search Data from March 6thIs this theHiggs Boson?No Higgs here!NoHiggshere!

  • It Walks and Quacks like a HiggsDo couplings scale ~ mass? With scale = v?

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

  • What else is there?SupersymmetrySuccessful prediction for Higgs massShould be < 130 GeV in simple modelsSuccessful predictions for Higgs couplingsShould be within few % of SM valuesNaturalness, GUTs, string, Could explain the dark matter

  • Lightest Sparticle as Dark MatterStable 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 pairsHeavier sparticles lighter sparticlesLightest supersymmetric particle (LSP) stablePresent in Universe today as relic from Big Bang


  • Relic Density CalculationFreeze-out from thermal equilibrium

    Typical annihilation cross section ~ 3 10-26 cm2Lower if coannihilation with related particles

  • Supersymmetric Signature @ LHCLook for missing transverse energy carried away by dark matter particles

  • Classic missing-energy searchSearches ~ 5/fb @ 8 TeVSupersymmetry Searches @ LHCMultiple searches including b, leptons

  • 5p-value of simple models < 10%2Scan of CMSSMImpacts of searcheswith full 2012 dataUpdate of Buchmueller et al: arXiv:1207.3715Global Fit to Supersymmetric Model

  • 51Favoured values of gluino mass significantlyabove pre-LHC, > 1.5 TeVGluino massUpdate of Buchmueller, JE et al: arXiv:1207.3715CMSSMGlobal Fit to Supersymmetric Model

  • Cosmological Inflation in Light of Planck

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

  • Inflationary Models in Light of PlanckPlanck CMB observations consistent with inflationTilted scalar perturbation spectrum:ns = 0.9585 0.070BUT strengthen upper limit on tensor perturbations: r < 0.10Challenge for simple inflationary modelsStarobinsky 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:0710.3755BUT: needs MH > 127 GeV LHC?

  • Supersymmetric Inflation in Light of PlanckSupersymmetric Wess-Zumino (WZ) model consistent with Planck data422/3Croon, JE, Mavromatos: arXiv:1303.6253WZ

  • No-Scale Supergravity InflationThe only good symmetry is a local symmetryEarly Universe cosmology needs gravitySupersymmetry + gravity = SupergravityBUT: potentials in generic supergravity models have potential holes with depths ~ MP4Exception: no-scale supergravityAppears in compactifications of stringFlat directions, scalar potential ~ global model + controlled correctionsJE, Nanopoulos & Olive, arXiv:1305.1247, 1307.3537

  • No-Scale Supergravity InflationGood inflation for Looks like R2 modelJE, Nanopoulos & Olive, arXiv:1305.1247, 1307.3537

  • Strategies for Detecting Supersymmetric Dark MatterScattering on nucleus in laboratory + A + AAnnihilation in core of Sun or Earth + + Annihilation in galactic centre, dwarf galaxies + ?Annihilation in galactic halo positrons, antiprotons, ?

  • Best limit: XENON100 with 225 days of dataConfusion at low WIMP masses?Aprile et al.Direct Searches for Dark MatterNew CDMS result

  • Favoured values of dark matter scatteringcross section significantly below XENON1005--- 1/fb___ 5/fbBuchmueller, JE et al: arXiv:1207.3715Spin-independentDark matter scatteringExcluded byXENON100Excluded by LHC2Global Fit to Supersymmetric Model

  • Strategies for Detecting Supersymmetric Dark MatterScattering on nucleus in laboratory + A + AAnnihilation in core of Sun or Earth + + Annihilation in galactic centre, dwarf galaxies + ?Annihilation in galactic halo positrons, antiprotons, ?

  • Neutralino Annihilation RatesIn somesupersymmetric modelsmay be much smaller than order-of-magnitudeestimateJE, Olive & Spanos, arXiv:1106.0768

  • Annihilation Branching FractionsVary in different regions of parameter spaceJE, Olive & Spanos, arXiv:1106.0768Must be modelled correctly

  • BUT: Fermi Collaboration also sees bump in control sample of s from Earths limbPresumably a systematic effectFermi line@ 130 GeV?Weniger analysisclaimed 4 (3 with look-elsewhere effect)

  • AMS-02 on International Space Station (ISS)

  • Positron Fraction Rising with EDark Matter? Galactic cosmic rays? Local sources?

  • Dark Matter Fit to AMS Positron DataCan find good fit: 2 ~ 18 with annihilation to +- by modifying cosmic ray parametersJE, Olive & Spanos, in preparation

  • Dark Matter Fit to AMS Positron DataBUT: very large annihilation cross section ~ 3 10-23 cm2 >> required for relic densityOR: 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 modelBUT: problems with e-, p_JE, Olive & Spanos, in preparation

  • Assume Local Source: Constrain any extra Dark Matter ContributionDark Matter annihilation could give feature above otherwise smooth distributionBergstrom et al, arXiv::1306.3983

  • The LHC may cast light on dark matter dark matter experiments may cast light onfundamental questions in particle physics