VIEWS: 14 PAGES: 41 POSTED ON: 9/17/2012
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?
"Gauguin's Questions in Particle Physics"