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intro to neutralino dark matter

intro to neutralino dark matter. Pearl Sandick University of Minnesota. Plan. Why study Supersymmetry? MSSM Neutralino Dark Matter Constrained MSSM. Why study SUSY?. Aesthetically “neat” extension. Stabilizes the Higgs vev (Hierarchy Problem). Gauge coupling unification.

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intro to neutralino dark matter

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  1. intro to neutralino dark matter Pearl Sandick University of Minnesota

  2. Plan • Why study Supersymmetry? • MSSM Neutralino Dark Matter • Constrained MSSM Pearl Sandick

  3. Why study SUSY? • Aesthetically “neat” extension • Stabilizes the Higgs vev (Hierarchy Problem) • Gauge coupling unification • Predicts a light Higgs boson Pearl Sandick

  4. Why study SUSY? • Aesthetically “neat” extension R. Haag, J. T. Lopuszanski and M. SohniusNucl. Phys. B 88 (1975) 257 Coleman-Mandula Theorem: “impossibility of combining space-time and internal symmetries in any but a trivial way” Phys. Rev. 159: 1251–1256 By including both commuting and anticommuting generators, get consistent theory with interplay of Poincaré and internal symmetries, i.e. boson fermion. Supersymmetry is the only nontrivial extension of the Pioncaré algebra in a consistent 4-d QFT. Pearl Sandick

  5. Why study SUSY? • Aesthetically “neat” extension • Stabilizes the Higgs vev (Hierarchy Problem) Classical Higgs Potential: V = mH2 ||2 + ||4 SM requires <>  0, so <> = (-mH2 / 2 )1/2  174 GeV  -mH2  (100 GeV)2 But mH2 gets quantum corrections from particles that interact with the Higgs field! Pearl Sandick

  6. SM: SUSY: Why study SUSY? • Aesthetically “neat” extension • Stabilizes the Higgs vev (Hierarchy Problem) • SUSY maintains hierarchy of mass scales. Pearl Sandick

  7. Just right! SUSY Why study SUSY? • Aesthetically “neat” extension • Stabilizes the Higgs vev (Hierarchy Problem) • Gauge coupling unification Near miss! SM Pearl Sandick

  8. Why study SUSY? • Aesthetically “neat” extension • Stabilizes the Higgs vev (Hierarchy Problem) • Gauge coupling unification • Predicts a light Higgs boson MSSM: 105 GeV < mh < 135 GeV LEP: 114.4 GeV < mh < 182 GeV ~ ~ LEP Collaborations and Electroweak Working Group, arXiv:0712.0929 Pearl Sandick

  9. Particle Zoo MSSM: Minimal Supersymmetric Standard Model Has the minimal particle content possible in a SUSY theory. Pearl Sandick

  10. quarks and squarks Fermions and sfermions leptons and sleptons W boson and wino gauge bosons and gauginos gluon and gluino Neutralinos! B boson and bino Higgs bosons and higgsinos Particle Zoo Pearl Sandick

  11. Caveat: The lightest SUSY particle (LSP) is stable if R-parity is conserved. +1 for SM particles -1 for sparticles R = (-1)3B+L+2S = • Why conserve R-parity? • Stability of proton • Neutron-antineutron oscillations • Neutrino mass • Ad hoc? • SO(10) GUTs • B and L numbers become accidental symmetries of SUSY Another reason to study SUSY: • Neutralinos are an excellent dark matter candidate! • The lightest one may be a stable WIMP with h2  DMh2 Pearl Sandick

  12. Another reason to study SUSY: • Neutralinos are an excellent dark matter candidate! • The lightest one may be a stable WIMP with h2  DMh2 Properties of neutralino LSP will depend on its composition. Pearl Sandick

  13. SUSY Breaking (what we do) • Don’t observe boson-fermion degeneracy, so SUSY must be broken (How?) • Most general case (MSSM) has > 100 new parameters! • OR make some assumptions about SUSY breaking at a high scale, and evolve mass parameters down to low scale for observables • Explicitly add [soft] SUSY-breaking terms to the theory: • Masses for all gauginos and scalars • Couplings for scalar-scalar and scalar-scalar-scalar interactions • CMSSM (similar to mSUGRA) • Assume universality of soft SUSY-breaking parameters at MGUT • Free Parameters: m0, m1/2, A0, tan(), sign() Pearl Sandick

  14. Neutralino Relic Density 1. Assume neutralinos were once in thermal equilibrium 2. Solve the Boltzmann rate equation to find abundance now Pearl Sandick

  15. Be careful! Situations when care must be taken to properly calculate (approximate) the relic density: 1. s - channel poles • 2 m  mA 2.Coannihilations • m  mother sparticle 3.Thresholds • 2 m  final state mass Griest and Seckel (1991) Pearl Sandick

  16. Constraints Apply constraints from colliders and cosmology: mh > 114 GeV m± > 104 GeV BR(b  s ) HFAG BR(Bs  +--) CDF (g -- 2)/2 g-2 collab. LEP 0.09  h2  0.12 Pearl Sandick

  17. Focus Point LEP Higgs mass Relaxed LEP Higgs LEP chargino mass 2 < 0 (no EWSB) g--2 suggested region stau LSP Coannihilation Strip CMSSM Pearl Sandick

  18. Rapid annihilation funnel 2m  mA bs B+-- CMSSM Pearl Sandick

  19. Detecting the Dark Matter • Direct detection • Solid state: CDMS, SuperCDMS, EDELWEISS… • Liquid nobles: XENON10, XENON100/LUX, ArDM, DEEP, CLEAN, WARP, ZEPLIN… • Indirect detection • Detect neutralino annihilation/decay products terrestrially (ICEcube, ANITA) or in space (PAMELA, GLAST) • Colliders Pearl Sandick

  20. Direct Detection If neutralinos are DM, they are present locally, so will occasionally bump into a nucleus. Effective 4-fermion lagrangianfor neutralino-nucleon scattering (velocity-independent pieces): spin independent (scalar) spin dependent • Fraction of nucleus participates • Important for capture & annihilation rates in the sun • Whole nucleus participates • Best prospects for direct detection Pearl Sandick

  21. Neutralino-Nucleon Scattering tan = 10, Min = MGUT • Pass all constraints (blue) • Only fail relaxed Higgs mass constraint (green) CDMS II (2006) XENON 10 SuperCDMS XENON 100 Pearl Sandick

  22. Neutralino-Nucleon Scattering tan = 10, Min = MGUT CDMS II (2006) XENON 10 SuperCDMS XENON 100 Pearl Sandick

  23. Neutralino-Nucleon Scattering tan = 50, Min = MGUT Pearl Sandick

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