November 24, Scalar Dark Matter from Grand Unified Theories. T. Daniel Brennan. Standard Model. Dark Matter. GUTs. Babu- Mohapatra Model

Transcription

1 Scalar from November 24, 2014

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3 What is the? Gauge theory that explains strong weak, and electromagnetic forces SU(3) C SU(2) W U(1) Y Each generation (3) has 2 quark flavors (each comes in one of three colors) and 2 leptons Each type of quark and lepton can have either left or right chirality except the neutrino Each left pair forms a doublet which transforms under SU(2) (couples to the weak force) Each quark flavor forms a triplet which transforms under SU(3) (couples to strong force) There is also a Higgs boson doublet (which transforms under SU(2)) Y = 2(Q I 3 )

4 What is the?

5 Mathematics of the Multiplets ( ) ( ) Q (c) u (c) νe L = E L = e d (c) L u (c) R d (c) R e R L φ = 1 2 ( φ + φ 0 ) Lagrangian L = Q L (i / + g W σ A /W A + g S T A /G A + g Y 3 / A)Q L + Ē L (i / + g W σ A /W A g Y /A)E L ) ( µ + ig W σ A Wµ A + ig Y A µ φ W a µνw aµν L Yukawa + V (φ)

6 Electroweak Symmetry Breaking At observable energies, the standard model breaks to SU(3) C U(1) EM At some energy level (standard model breaks around 246 GeV) Higgs boson gains value expectation value Reparametrize φ = v + σ

7 Results of Electroweak Symmetry Breaking After Electroweak Symmetry Breaking: Weak force propagators gain mass (part that breaks symmetry) Higgs boson mass changes Mass of particles coupled to Higgs boson by Yukawa term change

8 Running Gauge Coupling In the effective action of QFT, gauge couplings have quantum corrections given by higher order processes In renormalizing the gauge couplings, introduce a parameter µ (renormalization scale) with dimensions of energy. It describes how couplings change with energy scale of interactions.

9 Problems with the No quantum description of gravity Matter/anti-matter asymmetry Neutrino Mass Landau Pole Strong CP Problem Hierarchy Problem-Cancellation of quantum corrections to Higgs mass L-R Asymmetry/Irreducible representation of gauge group Gauge group structure unexplained

10 What is? Cold Non-relativistic at some comparable era of the universe Hot dark matter smooths out over density fluctuations 1keV Collisionless No scatters on average nσvτ univ 1 or Dark Does not couple to Photons Matter u DM T 3(1+w) with w 0 σ cm 1TeV M DM

11 Evidence Rotation Curves CMB Fluctuation density not enough to form structure Gravitational Lensing Bullet Cluster

12 Properties Interacts through Gravity Massive Makes up 85% of matter in Universe Is non-luminous neutral charge Does not react very much with normal baryonic matter unlikely to interact through the strong force WIMPs (Weakly Interacting Massive Particles) are an obvious choice for candidates

13 Cosmological Production WIMPs are theorized to have been created in their current abundance by Thermal Relic model Characteristic length scale of universe a T 1 n rel T 3 n non rel T 3/2 e m X /T n = d 3 p e E(p)/T ±1

14 Panoply of theories attempt to model dark matter observations. Several popular theories include: Neutralino - Supersymmetry Combination of photino, zino, and neutral higgsino Protected by R-Symmetry- lightest supersymmetric particle (LSP) Axion - Solution to Strong CP Problem L Axion = g 2 θ 32π 2 ɛ µνσρ G a µνg a σρ = g 2 θ 32π 2 G µν G µν Sterile Neutrino - Giving up on life Neutral leptons which only couple to gravity

15 Experiments Particle Accelerator Searches LHC Look for missing energy/momentum in measurements Direct Detection Large Underground Xenon experiment (LUX) Detect photons and electrons electroluminescence

16 Experiments Babu

17 What are? () extend standard model to a larger semisimple gauge group with single fundamental force by using spontaneous symmetry breaking as in electroweak symmetry breaking. Can be used to explain Matter/antimatter asymmetry Neutrino Mass L-R Asymmetry/Irreducible representation of gauge group Landau Pole????? Common are SU(5) and SO(10) predict Proton Decay

18 Higgs Sector To extend the standard model to a larger gauge group, need to add new scalar higgs multiplet to break gauge group down to standard model. Common Higgs multiplets are 5, 10, 16, 45, 54, 126, 144, 210 dimensional.

19 Favorable s Neutrino Mass Suppressed Proton Decay L-R Symmetry Irreducible Representation As few symmetry breaking steps as possible Suggests SO(10) model containing ? Higgs sector. Also want to try to incorporate candidates

20 Candidate Decomposition of a couple Higgs multiplets under various subgroups of SO(10) 45 Higgs 126 Higgs

21 Specifics Single step symmetry breaking M U GeV Higgs Sector Produces Seesaw mechanism which gives proper neutrino mass and mixing Highly suppressed Proton Decay Lifetime on order of years Current limit from Super-Kamiokande is years Currently working on calculating to 2-loop order At low energies, has color sextet and 2 identical weak triplets which transform under SM as (6, 1, 2/3) and (1, 3, 0) respectively Mass scale approx 1-10 TeV

22 Scalar 2006 Cirelli, Fornengo, and Strumia characterized scalar and fermionic 2-4 WIMP multiplets. First order approximation to this model. Total LHC Luminocity: 44.2 pb fb fb 1 =29.4 fb 1

23 Observations LUX data from Feb 2014 σ SI cm 2

24 Observations To complete the first order approximation need to check to make sure mass fits observation. Used to fix unification scale: M ω = 2 TeV M = 12 TeV M U GeV

25 Future Directions and Applicability Future Directions Calculate Proton decay rate to 2-loop Verify Stability Formulate dynamical thermal relic model Look for observable effects Applicability Provides a newly motivated theory of dark matter Will rule out or provide strong constraints on

26 Proton Decay Given: ψ 0 = ν c L ψ i = d c 1 d c 2 d c 3 e ν L ψ ij = 0 u c 3 u c 2 u 1 d 1 0 u c 1 u 2 d 2 0 u 3 d 3 0 e + 0 the gauge bosons couple ψ 0 to ψ ij and ψ ij to ɛ ijklm ψ k and ψ ij to either ψ ik or ψ kj. So we can have a boson X which takes d 3 X + e + and u 2 + X u c 1. This takes p π0 e +. L