exotic dark matter candidates - california institute of technology

Sterile Neutrinos Little Higgs Models Other Candidates Summary

Exotic Dark Matter Candidates

Ersen Bilgin

Department of PhysicsCalifornia Institute of Technology

Ph135c, Non-Accelerator Experimental Particle Physics

Outline

1 Sterile NeutrinosMotivationThe Model

2 Little Higgs ModelsMotivationThe Model

3 Other CandidatesSUSYLight Scalar Dark MatterWimpzillasUniversal Extra DimensionsMore Candidates

STERILE NEUTRINOS in νMSM

Asaka, Shaposhkinov and KusenkoStandard Model incomplete in Neutrino SectorBaryon asymmetry in the universeOrigin of Dark Matter

Adding three sterile neutrinos explains all this

INDIRECT HINTS

Consistent with neutrino oscillationsLightest can account for cosmological dark matterExplain observed velocities of pulsars by the emission oflight sterile neutrino in supernova explosionsX-ray photons speed up early star formation (WMAP)Heavy sterile neutrinos generate asymmetries betweensterile neutrinos and left-handed leptons

INDIRECT HINTS

The Model

LνMSM = LMSM + N I i∂µγµNI

−FαI ΦLαNI −MI

I NI + h.c. ,

(MD)T M I

), MD = F 〈Φ〉 (1)

mν = −MD 1MI

θ2 =1

∑α=eµτ

|MDα1|2

The Model

I NI + h.c. ,

(MD)T M I

), MD = F 〈Φ〉 (1)

mν = −MD 1MI

θ2 =1

∑α=eµτ

|MDα1|2

The Model

I NI + h.c. ,

(MD)T M I

), MD = F 〈Φ〉 (1)

mν = −MD 1MI

θ2 =1

∑α=eµτ

|MDα1|2

The Model

I NI + h.c. ,

(MD)T M I

), MD = F 〈Φ〉 (1)

mν = −MD 1MI

θ2 =1

∑α=eµτ

|MDα1|2

Constraints

θ < θmax (Ms) = 1.3× 10−4(

1 keVMs

)0.8to avoid overclosing

the universeθ > 5× 10−4 (1 keV/Ms)1/2 for the sterile neutrinos to bein thermal equilibriumVirgo cluster: θ < 1.6× 10−3 (1 keV/Ms)2, for1 keV < Ms < 10 keVX-ray background : θ < 5.8× 10−3 (1 keV/Ms)5/2, for1 keV < Ms < 100 keV

Constraints

θ < θmax (Ms) = 1.3× 10−4(

1 keVMs

Constraints

θ < θmax (Ms) = 1.3× 10−4(

1 keVMs

Constraints

θ < θmax (Ms) = 1.3× 10−4(

1 keVMs

SCENERIOS FOR ONE STERILE NEUTRINO

Scenerio INo sterile neutrinos at T > 1 GeV

Weak couplings between singlet fermions and fields beyondSM.θ = θmax (Ms) = 1.3× 10−4

(1 keV

)0.8for the right amount

of dark matterThis and Virgo cluster observations give Ms < 8 keVCMB, Lyman-α, Sloan Digital Sky Survey: Ms > 2 keV (dueto free streaming length of the sterile neutrino)

(1 keV

Scenerio IISterile Neutrinos at equilibrium at high temperature andabundance at EW scale is the same as active neutrinos

Force Ms ∼ 100 eVDoes not agree with Tremaine-Gunn bound:Ms > MTG ' 0.3 keV

Scenerio IIISterile Neutrinos at equilibrium at high temperature butnot through active sterile neutrino oscillations

Not studied muchθ < 2× 10−4 by X-ray observations not directly detectablein laboratoryMs > MTG ' 0.3 keV

Introduce two heavy sterile neutrinosNeed M ∼ O(1− 10) GeV to satisfy matter-antimatterasymmetry.also need heavy sterile neutrinos to be degenerate in mass

amplify CP-violating effects in sterile neutrino oscillations

Modify bound on Ms : Ms > 0.55 keVθ ∼ 9.2× 10−3

Can be falsified by neutrino physics dataIf Mini-Boone confirmed LSND results, need to add onemore neutrinoPreliminary results say it doesn’t.

Questions on νMSM

How does sterile neutrino decay into X-ray photon?N1 → γν, γν (similar to ultra-violet radiation from activeneutrino decays)

What happens to sterile neutrinos below equilibrium tempIt drops and currently it should be ∼ O(10) less than activeneutrinos

Explain Tremaine-Gunn Bound – Why doesn’t it apply toneutralinos?

Liouville’s Theorem: For non-interacting particles density offluid element in phase space does not change.Maximum coarse grained phase space density can onlydecrease.Apply this to isothermal gas spheres (neutrinos)

Questions on νMSM

LITTLE HIGGS MODELS

Alternative to SUSYHiggs mass quadratically divergent.To stabilize its mass need new physics at ∼ 1 TeVPrecision electroweak measurements give no evidence ofnew physics up to & 5− 7 GeVNot Natural.

LITTLE HIGGS MODELS

CHENG - LOW MODEL

5− 7 GeV bound assumes new fields couple at tree levelOnly need quantum loop diagrams to cancel quadraticdivergencesNo bound if interaction vertices involve Higgs and two ormore new TeV particlesIntroduce new symmetry “ T -Parity ” acting only on newparticlesAvoids Higgs interacting with one new TeV particle andrelaxes the constraints.

CHENG - LOW MODEL

T-PARITY’s PHENOMENOLOGICALCONSEQUENCES

Lightest particle that transforms under this symmetry (LTP)is stableIf charged leaves tracks, if neutral results in missing energyin collidersSimilar to R-parity conserving SUSY and KK-parityconserving UEDs.Spin is different from LSP, and easier to detect than KKexcitations.

Lightest T-odd Particle (LTP)

neutral B′ gauge boson with mass 600 GeV - 1.2 TeV givesthe right relic density for dark matter.

Annihilation of B′ into electron-positron pairs notsuppressed.Can be detected at the anti-matter detector on theInternational Space Station as a peak in the positronenergy distribution.

SU(2)W singlets and neutral components of some scalarfields are also DM candidates.

Supersymmetric Candidates

Sneutrinos: superpartners of SM neutrinos.mass ∼ 550 - 2300 GeVscattering cross section larger than the upper limits fromexperiments.

Gravitinos: Superpartners of GravitonsLightest SUSY particle and stable in some SUSY scenariosHard to detect since they only interact through gravitation

Axinos: Superpartners of AxionsPhenomenology similar to gravitinos.Can be cold, warm or hot DM candidate.

Light Scalar Dark Matter

For fermionic dark matter with standard Fermi interactions,mass of WIMPs . GeV (Lee and Weinberg)Other types of particles (scalar dark matter): mass 1-100MeV is possible511 keV gamma-ray line from the INTEGRAL satellite fromthe galactic bulge could be scalar dark matter annihilatinginto positrons which annihilate to give out the gamma rayline.Recently axinos or sterile neutrinos suggested to causethe 511 keV emission.

WIMPZILLAS

Unitarity bound gives maximum annihilation cross-sectionas a function of mass

Use WMAP constraint on ΩDMh2 to get mDM . 34 TeV

Wimpzillas were NOT in thermal equilibrium duringfreeze-outThey have mass > 1010 GeVcreated from gravitational production at the end of inflationMotivation: Cosmic rays above GZK cutoff (5× 1019 eV)

these rays interact at resonance with CMB photons souniverse should be opaque to them

WIMPZILLAS

Universal Extra Dimensions

Conservation of Momentum in higher dimensional spaceConservation of KK number in compactified spaceKaluza-Klein Particle

studied since 1984Lightest Kaluza-Klein Particle (LKP) has mass ∼ 400 to1200 GeVSee the Extra Dimensions talk on May 27.

Even more candidates

Q-Balls, mirror particles, CHArged Massive Particles(CHAMPs), self interacting dark matter, D-matter, cryptons,superweakly interacting dark matter, brane world darkmatter, heavy fourth generation neutrinos, etc.

Summary

Don’t know much about dark matterDifferent assumptions lead to different dark mattercandidatesNeed more experimental data to rule out or verify specificcandidates

Summary

Appendix

References I

G. Bertone, D. Hopper, J. SilkParticle Dark Matter: Evidence Candidates and Constraints

arXiv:hep-ph/0404175v2

T. Asaka, M. Shaposhkinov, A. KusenkoOpening a new window for warm dark matterarXiv:hep-ph/0602150v2

H. Cheng, I. LowTeV Symmetry and the Little Hierarchy ProblemarXiv:hep-ph/0308199v2

exotic dark matter candidates - california institute of technology

Documents