Hidden Dark Matter Sector Dark Radiation and CMB
Hidden Dark Matter Sector, Dark Radiation, and CMB ar. Xiv: 1505. 04192 [hep-ph] (Z. Chacko, Y. Cui, SH and T. Okui ) Sungwoo Hong University of Maryland-College Park
Outline 1. Motivation (why, why and WHAT ? ) 2. (Four) CMB Signals of Dark Radiation(s) 3. A Simple (and testable) Model 4. Conclusions Sungwoo Hong (U of Maryland) 2
1. Motivation- why Where is Dark Matter ? WIMPs ? We know there is Dark Matter ! Weakly Interacting Massive Particles (Planck 2015) DM SM WEAK DM http: //www. quantumdiaries. org/2013/06/26/does-dark-matter. Sungwoo Hong (U of Maryland) really-exist/ SM 3
1. Motivation- why Where is WIMP? Indirect Detection DM Recoil Energy SM Direct Detection Till date, no compelling evidence. . Missing Energy So, where are WIMPs really ? DM SM Production at Colliders Sungwoo Hong (U of Maryland) 4
1. Motivation- why Alternatives to simplest WIMP ? • Inelastic Dark Matter • Leptophilic Dark Matter • DM interacts only with heavier quarks • E. t. c. Sungwoo Hong (U of Maryland) 5
1. Motivation- why, why Hidden Sector Dark Matter One way to hide WIMPs from observation ! Weak Visible Invisible But Too But Weak suitable to for set thermal correct relic freeze-out density! ! Sungwoo Hong (U of Maryland) 6
Hidden Sector Dark Matter If WIMPs is realized via Hidden Sector, Q: How can we test this scenario by Then, existence of Light DOF is a robust prediction of the scenario ! experiments ? And, actually these light E. g. Can we observe DOFs must be Dark Radiation ? radiation, not matter ! Sungwoo Hong (U of Maryland) 7
1. Motivation- why, why and WHAT ? Hidden Sector Dark Matter Let’s play simplest game first ! Assume Hidden Sector consists of ONLY WEAK SCALE and MASSLESS states ! MASSLESS • Spin-0 Shift Symmetry (Goldstone Boson) • Spin-1/2 Chiral Symmetry • Spin-1 Gauge Invariance Sungwoo Hong (U of Maryland) 8
1. Motivation- why, why and WHAT ? Dark Radiation (DR) • Free streaming DR ! • Scattering DR ! Q: How can we test this scenario by Remarkably, CMB can tell us about experiments ? both existence and nature of interaction of DR’s !! E. g. Can we observe DR ? Sungwoo Hong (U of Maryland) 9
2. CMB signals of DR (1) CMB Signals of Dark Radiation (I) SM HS Sungwoo Hong (U of Maryland) 10
2. CMB signals of DR (2 and 3) CMB Signals of Dark Radiation (II, III) Free vs Scattering via Scalar Metric Perturbations Effects of SM free-streaming neutrinos on scalar component of CMB spectrum studied. 1. P. J. E. Peebles, Astrophys. J. 180, 1 (1973) 2. W. Hu and N. Sugiyama, Astrophys. J. 471, 542 (1996) 3. S. Bashinsky and U. Seljak, Phys. Rev. D 69, 083002 (2004) S. Bashinsky and U. Seljak, Phys. Rev. D 69, 083002 (2004) Sungwoo Hong (U of Maryland) 11
2. CMB signals of DR (2 and 3) CMB Signals of Dark Radiation (II, III) Free vs Scattering via Scalar Metric Perturbations We generalized these results to the case when there is additional radiation. Can Determine and Sungwoo Hong (U of Maryland) separately ! 12
2. CMB signals of DR (4) CMB Signals of Dark Radiation (IV) Free vs Scattering via Tensor Metric Perturbations We generalized this to arbitrary , Provided 1. S. Weinberg, Phys. Rev. D 69, 023503 (2004) 2. R. Flauger and S. Weinberg, Phys. Rev. D 75, 123505(2007) Sungwoo Hong (U of Maryland) 13
2. CMB signals of DR - Lower bound Robust Lower Bound of A robust lower bound on CMBPol CMB-Stage-IV will be sensitive to this ! CMB-Stage-IV Sungwoo Hong (U of Maryland) 14
4. Model Simple Model SM HS Sungwoo Hong (U of Maryland) 15
4. Model Simple Model Sungwoo Hong (U of Maryland) 16
5. Conclusion Hidden Sector WIMPs Dark Radiation ! Sungwoo Hong (U of Maryland) 17
Thank you ! Sungwoo Hong (U of Maryland) 18
Back-up: Motivation- why, why and WHAT ? Hidden Sector Dark Matter Q 1) WIMPs(weak scale) in Hidden Sector ? If WIMPs is realized via Hidden Sector, A 2) (I) For , A 2) (III) For A 1) Supersymmetry, Extra-dimension (e. g. RS). . . then, existence of Light DOF(s) in Hidden Sector violation of Lee-Weinberg not DM, but DR before and during is a robust prediction of the scenario ! (overclosure) matter-radiation equality ( ). bounds ( ). Observable signals in CMB ! Q 2) How light is Light DOF(s) ? (II) For , conflict with warm-DM constraints ( , 95 % CL) Sungwoo Hong (U of Maryland) 19
Back-up: CMB : mini review CMB: Mini-review Sungwoo Hong (U of Maryland) 20
Back-up: CMB : mini review CMB: Mini-review Comoving scales horizon re-entry Sub-horizon Super-horizon reheating CMB decoupling horizon exit Matter-radiation equality Sungwoo Hong (U of Maryland) Today t 21
Back-up: CMB : mini review CMB: Mini-review Comoving scales horizon re-entry Super-horizon RD MD CMB recombination reheating Sungwoo Hong (U of Maryland) Today t 22
Back-up: CMB signals of DR (4) – outline of derivation CMB Signals of Dark Radiation (IV) Free vs Scattering via Tensor Metric Perturbations 1. S. Weinberg, Phys. Rev. D 69, 023503 (2004) 2. R. Flauger and S. Weinberg, Phys. Rev. D 75, 123505(2007) Sungwoo Hong (U of Maryland) 23
Back-up: Relic Abundance Calculation for SM HS Sungwoo Hong (U of Maryland) 24
Back-up: Model – kinetic decoupling SM-DS Simple Model Thermal (kinetic) decoupling of DM from the SM bath Recall Sungwoo Hong (U of Maryland) 25
Backup Slides Comoving scales horizon re-entry Sub-horizon Super-horizon reheating horizon exit Sungwoo Hong (U of Maryland) CMB recombination t 26
Backup Slides Comoving scales horizon re-entry Super-horizon RD MD reheating t Sungwoo Hong (U of Maryland) 27
Backup Slides Sungwoo Hong (U of Maryland) 28
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