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Gauguin's Questions in Particle Physics

VIEWS: 14 PAGES: 41

									       Dark Matters




               Outlook
    for the Dark Matter horse race
                 John Ellis
Theory Division, Physics Department, CERN
A Strange Recipe for a Universe




    The Standard Model of cosmology
Dark Matter in the Universe
Dark Matter in the Universe
Astronomers say
Astronomers the
that most of tell
us that in the
matter most of the
matter in is
Universethe
universe
invisibleis
invisible
Dark Matter
‘Supersymmetric’ particles ?
 We will look for it
We shall look for
   with with the
  them the LHC
       LHC
    Why Supersymmetry (Susy)?

•   Intrinsic beauty
•   Hierarchy/naturalness problem
•   Unification of the gauge couplings
•   Predict light Higgs < 150 GeV
    – As suggested by precision electroweak data
• Cold dark matter
• Essential ingredient in string theory (?)
 Loop Corrections to Higgs Mass2
• Consider generic fermion and boson loops:


                                      Λ 4
• Each is quadratically divergent:   ∫ d k/k2
                    2




• Leading divergence cancelled if
                           x 2 Supersymmetry!
                        Reasons to like Susy
 It enables the gauge couplings to unify
 It predicts mH < 150 GeV




JE, Nanopoulos, Olive + Santoso: hep-ph/0509331
  As suggested by EW data
Minimal Supersymmetric Extension of
     Standard Model (MSSM)
• Particles + spartners


• 2 Higgs doublets, coupling μ, ratio of v.e.v.’s = tan β
• Unknown supersymmetry-breaking parameters:
      Scalar masses m0, gaugino masses m1/2,
      trilinear soft couplings Aλ, bilinear soft coupling Bμ
• Assume universality? constrained MSSM = CMSSM
      Single m0, single m1/2, single Aλ, Bμ: not string?
• Not the same as minimal supergravity (mSUGRA)
• Gravitino mass, additional relations
             m3/2 = m0, Bμ = Aλ – m0
      Non-Universal Scalar Masses
• Different sfermions with same quantum #s?
     e.g., d, s squarks?
     disfavoured by upper limits on flavour-
           changing neutral interactions
• Squarks with different #s, squarks and sleptons?
     disfavoured in various GUT models
     e.g., dR = eL, dL = uL = uR = eR in SU(5), all in SO(10)
• Non-universal susy-breaking masses for Higgses?
    Why not! 1 or 2 extra parameters in NUHM1,2
       Possible Nature of LSP
• No strong or electromagnetic interactions
     Otherwise would bind to matter
     Detectable as anomalous heavy nucleus
• Possible weakly-interacting scandidates
     Sneutrino
          (Excluded by LEP, direct searches)
     Lightest neutralino χ (partner of Z, H, γ)
     Gravitino
           (nightmare for astrophysical detection)
  Constraints on Supersymmetry
• Absence of sparticles at LEP, Tevatron
     selectron, chargino > 100 GeV
     squarks, gluino > 300 GeV
• Indirect constraints            3.3 σ
                                effect in
     Higgs > 114 GeV, b → s γ    gμ – 2?

• Density of dark matter
     lightest sparticle χ:
     0.094 < Ωχh2 < 0.124
       Current Constraints on CMSSM
    Assuming the
   lightest sparticle
     is a neutralino

Excluded because stau LSP


Excluded by b  s gamma

WMAP constraint on relic density

Preferred (?) by latest g - 2


                                   JE + Olive + Santoso + Spanos
    Sparticles may not be very light
     Full




                                                             ← Second lightest visible sparticle
    Model
   samples

 Provide
Dark Matter

 Detectable
  @ LHC

Dark Matter
Detectable
 Directly

              Lightest visible sparticle →   JE + Olive + Santoso + Spanos
Global SUSY Fits to all Data
        How Soon Might the CMSSM be
                 Detected?




O.Buchmueller et al
        How Soon Might the NUHM1 be
                 Detected?




O.Buchmueller et al
          CMSSM with 1/fb of LHC Data




O.Buchmueller et al
          NUHM1 with 1/fb of LHC Data




O.Buchmueller et al
                      Best-Fit Spectra
      • CMSSM                  • NUHM1




O.Buchmueller et al
                      (In)Sensitivity to WMAP




O.Buchmueller et al
              Sensitivity to Uncertainties
    • g - 2                 • b  s




O.Buchmueller et al
Prospects for Space Experiments
           First Results from PAMELA

   • Deflection distribution    • Antiproton/proton ratio




Boezio et al: arXiv:0810.3508
    First Results NOT from PAMELA
• Positron fraction: copied from   • Antiproton/proton ratio
  talk                             • Combined fit in model
• Not published by PAMELA




Cirelli et al: arXiv:0802.3378
        Galactic Secondary Positron Flux
    • Update Moskalenko & Strong using new nuclear cross sections
    • Include theoretical uncertainties
    • Independent model of cosmic-ray propagation




Delahaye et al: arXiv:0809.5268
           Pulsars as Sources of Positrons
    • Important contributions from both sources
         – Geminga, B0656+14, …
      and from distant pulsars (> 500 pcs)
    • Nearby sources would generate small but significant dipole
      anisotropy in electron spectrum




Hooper et al: arXiv:0810.1527
Big-Bang Nucleosynthesis Constraint
• Dark Matter annihilations constrained by light-
  element abundances and Big-Bang Nucleosynthesis
• Upper limits from:
    – 4He, D, 7Li, 6Li
• Possible lower limit:
    – 6Li




 Hisano et al: arXiv:0810.1892
  Positrons,  Rays and Light Nuclei
• Dark Matter annihilations constrained by light-element
  abundances and Big-Bang Nucleosynthesis
• Positrons may need enhancement by lumpy halo ‘boost factor’
• Possible signal in  rays




Hisano et al: arXiv:0810.1892
            What Type of Dark Matter?
• Dark Matter with mass 150 GeV annihilating into WW
• OK for positron fraction
• Not for e- + e+, antiprotons




Cirelli et al: arXiv:0809.2409
            What Type of Dark Matter?
• Dark Matter with mass 1 TeV annihilating into +- (!)
• OK for positron fraction
• Also OK for e- + e+, antiprotons




Cirelli et al: arXiv:0809.2409
            What Type of Dark Matter?
• Dark Matter with mass 10 TeV annihilating into WW
• OK for positron fraction
• So-so for e- + e+, OK for antiprotons




Cirelli et al: arXiv:0809.2409
How is the Other Horse Doing?
         The Large Hadron Collider (LHC)



Proton- Proton Collider


    7 TeV + 7 TeV



Design luminosity 1034 cm-2s-1:       Primary targets:
Possibility of increase by 10: SLHC   •Origin of mass
                                      •Nature of Dark Matter
                                      •Primordial Plasma
                                      •Matter vs Antimatter
First Beam Circuit on Sept. 10th
Hundreds of Turns
Beam capture by RF and Bunching
It Works!
CMS ECAL vs HCAL
The LHC Enters Popular Culture
      Temporary Halt to Operations
• Electrical fault in connection
  between two magnets
• Ohmic heating broke
  cryostat, vacuum pipe
• Repairs during regular
  winter shutdown
• Precursor diagnostic
  identified
• Simple rewiring can prevent
  recurrence
      Plans for 2009 and Beyond

• Next year:
  –   Initial collisions at 450 GeV per beam
  –   Then accelerate to 7 TeV per beam
  –   Check out accelerator and detectors
  –   Start testing Standard Model
• Must wait 2 or 3 years for answer about the
  Higgs
• Who knows when physics beyond the
  Standard Model may appear?

								
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