Dark Matter Out of Seclusion ∗ Brian Batell Perimeter Institute ∗ with Maxim Pospelov and Adam Ritz - arXiv:0903.0363 - arXiv:0903.3396
Overview • Secluded WIMPs • Out of seclusion via – Colliders ∗ Higgs-strahlung at B-factories – Direct detection experiments ∗ Endothermic and exothermic inelastic scattering ∗ Higher order elastic scattering 1
Secluded Dark Matter Pospelov, Ritz, Voloshin ’07 V µν B µν χ SM Holdom ’86 2
“Secluded” regime • m χ > m V – Annihilation via χχ → V V – Relic abundance independent of kinetic mixing – Makes direct detection, collider signatures tricky if mixing small. Can’t rule out WIMP hypotheses in principle if secluded χ V V χ 3
Astrophysical signatures 1) Light mediator − → enhanced galactic annihilation cross section • e.g. Sommerfeld enhancement: long range force distort wavefunctions near the origin from the plane wave to the Coulomb-type. Arkani-Hamed, Finkbeiner, Slatyer, Weiner ’08 Pospelov, Ritz ’08 N ∼ πα ′ v 2) m V ≤ GeV = ⇒ vector won’t decay to (anti-)protons by kinematics Connection with PAMELA, ATIC, FERMI, HESS, ...? 4
B-factory Signatures BB, Pospelov, Ritz ’09; Essig, Schuster, Toro ’09; Reece, Wang ’09; 5
B-factories B -factory (BaBar and Belle) advantages: • Large data sets ∼ 500 fb − 1 • COM energy √ s ≃ 10 GeV, close to masses of new particle 6
2 V µν F µν + m 2 L int = − κ v ′ h ′ V 2 V µ • Higgs ′ -strahlung: e + e − → γ ∗ , V ∗ → h ′ V • Cross section σ ∼ 20 fb • Leads to 6 lepton final state 7
V µ decays 10 4 1.00 0.50 10 5 0.20 0.10 GeV 10 6 Br V 0.05 V 0.02 10 7 0.01 10 8 0.1 0.2 0.5 1.0 2.0 5.0 10.0 0.1 0.2 0.5 1.0 2.0 5.0 10.0 m V GeV m V GeV • V → hadrons (Red) • V → e + e − (Blue) • V → µ + µ − (Green) V µ always has a significant branching to leptons 8
h ′ decays 1 1 10 4 0.001 10 8 10 6 h ’ GeV Br h ’ 10 12 10 9 10 16 10 12 10 20 10 24 10 15 0.1 0.2 0.5 1.0 2.0 5.0 10.0 0.1 0.2 0.5 1.0 2.0 5.0 10.0 m h ’ GeV m h ’ GeV • h ′ → V V (Red) • h ′ → e + e − (Blue) • h ′ → µ + µ − (Green) -Decays of h ′ depend on whether m h ′ > m V or m h ′ < m V 9
Sensitivity 10.0 10.0 5.0 5.0 2.0 2.0 m h ’ GeV m h ’ GeV 1.0 1.0 0.5 0.5 0.2 0.2 0.1 0.1 0.1 0.2 0.5 1.0 2.0 5.0 10.0 0.1 0.2 0.5 1.0 2.0 5.0 10.0 m V GeV m V GeV • 2 l + missing energy (light) • 6 e (medium) • 6 µ (dark) 10
Direct Detection Finkbeiner, Slatyer, Weiner, Yavin ’09; BB, Pospelov, Ritz ’09; 11
Multi-component WIMPs • If WIMP is a complex scalar or Dirac fermion, the real components χ, χ ′ can be split after U(1) S is broken so that ∆ m = m χ 2 − m χ 1 � iχ i σ µ ∂ µ χ i − 1 � � − ie ′ V µ (¯ L = 2( mχ i χ i + h . c . ) χ 1 σ µ χ 2 − ¯ χ 2 σ µ χ 1 ) i =1 , 2 • No tree level elastic scattering process χ 1 N → χ 1 N • Example of inelastic dark matter Smith, Weiner ’01 • Direct detection depends sensitively on ∆ m 12
Rich scattering structure • Endothermic inelastic : χ 1 N → χ 2 N • Exothermic inelastic : χ 2 N → χ 1 N (depends on χ 2 population) • Second-order elastic : χ 1 N → virtual states → χ 1 N χ 1 χ 2 χ 1 χ 2 χ 1 V V γ γ N N 13
� � Elastic: χ 1 N → χ 1 N m 200 GeV 1 10 1 • CDMS constraints ( ∆ m = 10 MeV) 10 2 10 3 10 4 10 5 10 20 50 100 200 500 1000 m V MeV Sensitivity diminishes as WIMP probes nucleus 14
Exothermic: χ 2 N → χ 1 N • Requires substantial population of excited WIMPs χ 2 • Decay of χ 2 in ‘minimal’ U(1) S model: ⇒ rapid decay χ 2 → χ 1 + e + e − – ∆ m > 2 m e = – ∆ m < 2 m e = ⇒ Loop induced χ 2 → χ 1 + 3 γ � κ � 13 � 100 MeV � 4 � 2 � ∆ m τ > 4 × 10 − 47 GeV × 10 − 3 100 keV m V • χ 2 lifetime longer than the age of the universe for small ∆ m . 15
� � � � Exothermic: χ 2 N → χ 1 N m 1 TeV, v E 500 km s m 100 GeV, v E 500 km s 10 4 10 4 10 5 10 5 10 6 0 50 100 150 200 0 50 100 150 200 m keV m keV • DAMA preferred region 90(99)% CL - dark(light) – endothermic (solid) – exothermic (dashed) 16
Conclusions • Secluded WIMPS • B -factory signals: – Higgs ′ -strahlung → multi-lepton final state – Probe U (1) S couplings κ ∼ O (10 − 2 − 10 − 3 ) • Rich direct detection phenomenology – Endothermic, exothermic, and (2nd order) elastic scattering provide sensitivity for different ranges of parameter space 17
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