The WIMP Miracle and Neutralino with Thermal History Physics & - PowerPoint PPT Presentation

PH489 Particle Physics The WIMP Miracle and Neutralino with Thermal History Physics & Computer, KAIST Young-kyoung Bae ( 배영경 )

Introduction

Introduction Milky Way

Introduction Dark Matter Properties 1) Non-relativistic 2) Non-baryonic 3) Stable ( long life-time)

Introduction Without any specific model … Ultra-light scalar Fermions Pauli exclusion (extremely light bosons) ● ● No limit of occupation number The uncertainty principle ●

Introduction Without any specific model … Ultra-light scalar Fermions Pauli exclusion (extremely light bosons) ● Too Wide ● No limit of occupation number The uncertainty principle ●

Introduction Dark Matter (DM) relic abundances …? 1) Thermal Production (TP) - e.g. WIMP 2) Non-thermal Production (NTP) - e.g. Axion

Thermal History Interaction rate Expansion rate Thermal equilibrium Decouple

The WIMP Miracle…? Assumption 1) 2) The cold DM (CDM) The Boltzmann equation where L : the Liouville operator, C : the collision operator and f : the phase-space density

The WIMP Miracle…? Assumption The Boltzmann equation 1) 2) The cold DM (CDM) where

The WIMP Miracle…? Assumption 1) 2) The cold DM (CDM) 3) Thermal equilibrium (Fermi-Dirac or Bose-Einstein) where 4) (the Maxwell-Boltzmann dist) 5) The SM particles go quickly in equilibrium (photon bath)

The WIMP Miracle…? Assumption 1) 2) The cold DM (CDM) 3) Thermal equilibrium (Fermi-Dirac or Bose-Einstein) 4) (the Maxwell-Boltzmann dist) 5) The SM particles go quickly in equilibrium (photon bath)

The WIMP Miracle…? 1) 2)

The WIMP Miracle…? Relativistic limit Non-relativistic limit

The WIMP Miracle…? Relativistic limit Non-relativistic limit

The WIMP Miracle…? where

The WIMP Miracle…? taking

The WIMP Miracle…? The WIMPless DM model 1) SIMP (Strongly Interacting Massive Particle) 2) Forbidden DM ( )

Neutralino Hypothetical particle of SUSY ● ● The most promising candidate of DM It is composed of two electrical neutral gaugino( wino and ● bino ) and higgsinos (the superpartners of neutral Higgs bosons) ● Majorana fermionic mass eigenstate

Neutralino 1) well-tempered neutralino (the mix of bino-wino-higgsino for the LSP) 2) co-annihilations 3) resonance annihilation, etc.

Neutralino

Detection Strategies 1) Direct Detection The nuclear recoil energy

Detection Strategies 1) Direct Detection Scattering rate ( the differential rate per unit detector mass)

Detection Strategies 1) Direct Detection Annual Modulation the flux of DM ● June > Dec ● gravitational focusing

Detection Strategies 2) Indirect Detection Detect the products of DM annihilation

Summary ● We briefly saw the properties of DM ● We calculated the range of DM by using the properties. (But it was too wide…!) ● So we concerned about the DM relic abundances to determine the specific model.

Summary ● The WIMP Miracle…? - The mass seems to be weak scale. - But, the important thing is the ratio. ● So there are many different models - e.g., SIMP, Forbidden DM, etc.

Summary ● Neutralino - The hypothetical particle of SUSY theories. - After discovery of Higgs, the higgsino is the most candidate of WIMP DM. ● Detection Strategies

Thank you

Appendix A The geodesic equation The Liouville operator homogeneous & isotropic

Appendix A

Appendix B Interaction rate Expansion rate Before the electroweak symmetry breaking Thermal equilibrium Decouple

Appendix B Interaction rate Expansion rate After the electroweak symmetry breaking Thermal equilibrium Decouple