Journeys Beyond the Standard Model by Gilly Elor A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Physics in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Lawrence J. Hall, Chair Professor Raphael Bousso Professor Chung-Pei Ma Spring 2013 Journeys Beyond the Standard Model Copyright 2013 by Gilly Elor 1 Abstract Journeys Beyond the Standard Model by Gilly Elor Doctor of Philosophy in Physics University of California, Berkeley Professor Lawrence J. Hall, Chair The much anticipated era of the Large Hadron Collider is finally upon us, making to- day an extremely interesting time to be doing theoretical particle physics. The recent Higgs-like signal is certainly the most exciting particle physics discovery in decades. However with this discovery comes the reminder that we are now, more than ever, in need of theoretical work to understand new physics. The Standard Model is incom- plete; it does not accommodate the experimental observation of dark matter, or the baryon asymmetry of the Universe. In addition, the SM has aesthetic or fine-tuning problems, like the gauge hierarchy problem and the strong CP problem. The task of model builders centers around addressing these and other issues by constructing new physics models that may be tested experimentally. i To Aviva and Arye Dror, ii Contents List of Figures v List of Tables vii 1 Introduction 1 1.1 The Gauge Hierarchy Problem . 2 1.1.1 Supersymmetry . 4 1.1.2 Calling Naturalness into Question . 5 1.2 Dark Matter . 7 1.2.1 Thermal Freeze-Out . 7 1.2.2 Dark Matter Candidates . 9 1.2.3 Alternatives Production Mechanisms . 10 1.3 The Strong CP Problem . 10 1.4 Baryogenesis . 11 1.5 Published Work . 13 I Dark Matter 14 2 Hidden Sector Dark Matter 15 2.1 Two-Sector Cosmology . 18 2.1.1 Visible Sector Freeze-Out (FO) . 20 2.1.2 Hidden Sector Freeze-Out (FO0) . 21 2.1.3 The Portal . 22 2.1.4 Freeze-Out and Decay (FO&D) . 23 2.1.5 Freeze-In (FI) . 24 2.1.6 Re-Annihilation . 25 2.1.7 Sector Equilibration . 29 2.1.8 Summary of Results . 30 2.2 Cosmological Phase Diagrams . 32 2.2.1 Behavior of Phase Space Diagram . 36 2.3 Dark Matter Asymmetry . 38 iii 2.3.1 Asymmetric FI and Asymmetric FO&D . 38 2.3.2 Cosmological Phase Diagrams for DM Asymmetries . 43 2.4 Conclusions . 44 3 Hidden Sector Dark Matter at Colliders 45 3.1 Two-Sector Setup . 47 3.2 Operator Analysis . 49 3.2.1 Bino Portal . 51 3.2.2 Higgs Portal . 53 3.3 Freeze-Out and Decay (FO&D) . 55 3.3.1 Spectator Fields in Freeze-Out and Decay . 55 3.3.2 Theories of Freeze-Out and Decay . 56 3.3.3 Collider Signatures of Freeze-Out and Decay . 57 3.4 Freeze-In (FI) . 61 3.4.1 Spectator Fields in Freeze-In . 61 3.4.2 Theories of Freeze-In . 61 3.4.3 UV Sensitivity of Freeze-In . 63 3.4.4 Collider Signatures of Freeze-In . 63 3.5 Detection Prospects at the LHC . 66 3.5.1 Charged or Colored LOSP . 66 3.5.2 Neutral LOSP . 67 3.6 Discussion . 68 3.6.1 Signals from Freeze-Out and Decay and Freeze-In . 69 3.6.2 An example: ~l± l±x~0 ..................... 71 3.6.3 Signals from Re-Annihilations! and Asymmetry . 74 4 Gravitino Dark Matter from Freeze-In 76 4.1 Gravitino Cosmology . 79 4.1.1 Modes of Production . 80 4.1.2 Reconstructing the Origins of Dark Matter . 82 4.2 Conclusions . 84 II The Strong CP Problem 85 5 The Cosmological Axino Problem 86 5.1 Supersymmetric Axion Theories . 89 5.1.1 A Simple Theory . 90 5.2 Axino Cosmology . 91 5.2.1 Cosmological Axino Problem . 92 5.3 Gravitino and Axino Cosmology . 94 5.3.1 Three Scenarios for Dark Matter . 95 iv 5.3.2 Cosmological Bounds from Saxions . 98 5.4 Conclusions . 100 III Origins of the Matter - Antimatter Asymmetry 101 6 Bubble Baryogenesis 102 6.1 Introduction . 102 6.2 General Considerations . 104 6.2.1 Vacuum Structure and Tunneling . 104 6.2.2 B and CP Violation . 107 6.2.3 Asymmetry Generation: Instanton . 108 6.2.4 Approximating the Instanton . 112 6.2.5 Asymmetry Generation: Collisions . 113 6.2.6 Washout and Decay . 118 6.3 Toy Model . 121 6.3.1 Model Definition . 121 6.3.2 The Instanton . 123 6.3.3 Before Percolation . 124 6.3.4 After Percolation . 126 6.4 More Realistic Models . 128 6.4.1 Neutrino Seesaw . 128 6.4.2 Color-Breaking Minima . 129 6.5 Observational Consequences . 130 6.6 Future Directions . 131 Bibliography 133 v List of Figures 1.1 Gauge coupling unification in the SM and MSSM . 3 1.2 Thermal Freeze-Out . 8 2.1 Possible production mechanism of hidden sector dark matter . 17 2.2 Hidden and visible sector Freeze-Out . 21 2.3 Freeze-Out and Decay . 23 2.4 Freeze-In . 24 2.5 Freeze-In with re-annhilations . 26 2.6 Re-annhilations in both Freeze-In and Freeze-Out and Decay . 27 2.7 Cosmological phase diagram . 33 2.8 Variation in cosmological phase diagrams with σv . 36 h i 2.9 Variation in cosmological phase diagrams with ξUV. 37 2.10 Variation of cosmological phase diagrmas with m0 . 38 2.11 Cosmological phase diagrams including asymmetric production mech- anisms. 42 3.1 Allowed decays among visible and hidden sector states. 48 3.2 Cosmological history of FO&D. 55 3.3 Cosmological history of FI. 60 3.4 Signal topologies at displaced vertices from LOSP decays induced by R-parity even X0.............................. 69 3.5 Signal topologies at displaced vertices from LOSP decays induced by R-parity odd X0 .............................. 70 3.6 Simulation of a kinked track event . 71 3.7 Projected decay lengths . 72 2 4.1 Contours of Ω3=2h = 0:11 for gaugino masses fixed . 78 2 4.2 Contours of Ω3=2h = 0:11 for universal scalar masses fixed to 500 GeV. 79 4.3 Prediction of τNLSP for gravitino dark matter arising from freeze-in, for mNLSP = 300 GeV. 82 5.1 The cosmological gravitino and axino problems . 88 2 5.2 Contours of Ωa~h = 0:11 for the KSVZ axion model . 92 vi 2 5.3 Contours of Ωa~h = 0:11 for the DFSZ axion model . 93 12 5.4 Phase space for gravitino dark matter with fa = 10 GeV . 94 9 5.5 Phase space for gravitino dark matter with fa = 10 GeV . 95 5.6 Gravitino dark matter in Region II, . 98 6.1 Sample scalar potential in Bubble Baryogenesis . 104 6.2 Simplified bubble collision geometry . 106 6.3 Sample instanton profiles for the fields R and θ as a function of radial coordinate ρ in a potential that breaks U(1)B. 108 6.4 The trajectory in field space taken by the \curvey" Euclidean instanton solution . 109 6.5 The total B that results from a numeric simulation of an expanding 1+1-dimensional domain wall. 110 6.6 Sample field profiles of a collision event at three different times. 114 6.7 Re(φ) as function of space and conformal time η during a bubble col- lision showing oscillatory behavior . 116 6.8 The baryon number density as a function of space and conformal time η for the same collision as Fig. 6.7 . 117 6.9 The total baryon number B as a function of conformal time for the same collision as Fig. 6.7 . 118 6.10 Re(φ) as function of space and conformal time η during a bubble col- lision showing creation and collapse of pockets of false vacua . 119 6.11 ∆S^(z) for the potential in Eq. (6.33). 122 6.12 Plot of the exact value for µ2 divided by our parametric estimate. 125 6.13 Sample parameter space for the toy model. 127 vii List of Tables 2.1 Temperatures associated with each hidden sector dark matter produc- tion mechanism . 31 3.1 Reconstructing FO&D and FI at the LHC . 47 3.2 R-charge and parity of Portal Operators . 50 3.3 Decay modes and decay rates for LOSP candidatesχ ~0 and `~, relevant for FO&D, with X0 R-parity even . 57 3.4 Decay modes and decay rates for LOSP candidatesχ ~0 and `~, relevant for FO&D,.