Overview Secluded WIMPs Out of seclusion via Colliders - - PowerPoint PPT Presentation

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

VµνBµν

χ SM

Holdom ’86

2

“Secluded” regime

χ V V χ

• mχ > mV

– 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

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) mV ≤ 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

Lint = −κ 2 VµνF µν + m2

V

v′ h′V 2

µ

• Higgs′-strahlung: e+e− → γ∗, V ∗ → h′V
• Cross section σ ∼ 20 fb
• Leads to 6 lepton final state

7

Vµ decays

1.0 0.5 2.0 0.2 5.0 0.1 10.0 10 8 10 7 10 6 10 5 10 4 mV GeV

GeV 1.0 0.5 2.0 0.2 5.0 0.1 10.0 1.00 0.50 0.20 0.10 0.05 0.02 0.01 mV GeV BrV

• V →hadrons (Red)
• V → e+e− (Blue)
• V → µ+µ− (Green)

Vµ always has a significant branching to leptons

8

h′ decays

1.0 0.5 2.0 0.2 5.0 0.1 10.0 10 24 10 20 10 16 10 12 10 8 10 4 1 mh’ GeV

1.0 0.5 2.0 0.2 5.0 0.1 10.0 10 15 10 12 10 9 10 6 0.001 1 mh’ GeV Brh’

• h′ → V V (Red)
• h′ → e+e− (Blue)
• h′ → µ+µ− (Green)
• Decays of h′ depend on whether mh′ > mV or mh′ < mV

9

Sensitivity

1.0 0.5 2.0 0.2 5.0 0.1 10.0 1.0 0.5 2.0 0.2 5.0 0.1 10.0 mV GeV mh’ GeV 1.0 0.5 2.0 0.2 5.0 0.1 10.0 1.0 0.5 2.0 0.2 5.0 0.1 10.0 mV GeV mh’ GeV

• 2l+ missing energy (light)
• 6e (medium)
• 6µ (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 = mχ2 − mχ1 L =

• i=1,2
• iχiσµ∂µχi − 1

2(mχiχi + h.c.)

• − ie′Vµ(¯

χ1σµχ2 − ¯ χ2σµχ1)

• No tree level elastic scattering process χ1N → χ1N
• Example of inelastic dark matter

Smith, Weiner ’01

• Direct detection depends sensitively on ∆m

12

Rich scattering structure

χ1 χ2 N

V

γ χ1 χ2 χ1 N

V

γ

• Endothermic inelastic:

χ1N → χ2N

• Exothermic inelastic:

χ2N → χ1N (depends on χ2 population)

• Second-order elastic:

χ1N → virtual states → χ1N

13

Elastic: χ1N → χ1N

10 20 50 100 200 500 1000 10 5 10 4 1 mV MeV

m 200 GeV

• 10 3

10 2 10 1

• CDMS constraints

(∆m = 10 MeV) Sensitivity diminishes as WIMP probes nucleus

14

Exothermic: χ2N → χ1N

• Requires substantial population of excited WIMPs χ2
• Decay of χ2 in ‘minimal’ U(1)S model:

– ∆m > 2me = ⇒ rapid decay χ2 → χ1 + e+e− – ∆m < 2me = ⇒ Loop induced χ2 → χ1 + 3γ τ > 4 × 10−47 GeV × κ 10−3 2 ∆m 100 keV 13 100 MeV mV 4

• χ2 lifetime longer than the age of the universe for small ∆m.

15

Exothermic: χ2N → χ1N

50 100 150 200 10 5 10 4

m keV

m 100 GeV, vE 500 km s

• 50

100 150 200 10 6 10 5

m 1 TeV, vE 500 km s

10 4

• 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

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