Universums gtor

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Kaluza-Klein (KK) Dark Matter
Torsten Bringmann, SISSA
ENTApP Visitor Program and Workshop on Dark
Matter, SISSA, Trieste, 12-21 Oct 05
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Outline
a viable dark matter candidate
- the positron peak
- the gamma-ray spectrum
- antiprotons
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Outline
Why should we be interested in this particular
dark matter candidate?
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Extra dimensions the basic idea
Compactify extra dimensions on some small scale
R
2 R
Fig. Greene 00
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Universal Extra dimensions (UED)
Appelquist, Cheng Dobrescu, PRD 01
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The field content in 4D
At the first KK level, one finds the following
mass eigenstates
Vector bosons
Scalars
Ghosts
Fermions
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The lightest Kaluza-Klein particle
Does this give a viable dark matter candidate?
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What is the LKP?
Cheng, Matchev Schmaltz, PRD 02
At tree level, the mass of the KK modes is given
by
The LKP is given by the B(1)
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The LKP as a dark matter particle
The WMAP bound translates into
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Collider bounds
- Direct non-detection
R-1 ? 300 GeV
Appelquist, Cheng Dobrescu, PRD 01
Agashe, Deshpande Wu, PL B 01
- Electroweak precision tests
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Indirect detection
B(1) B(1) annihilation ratios at tree level
- 59 into leptons
Compare to SUSY!
- 35 into quarks
- 4 into neutrinos
- 2 into gauge and Higgs bosons
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The positron peak
Appearance of a smoking gun signature in the
spectrum.
HK
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The gamma-ray spectrum
Bergström, T.B., Eriksson Gustafsson, PRD 05
At high energies, the gamma-ray spectrum is
dominated by internal bremsstrahlung from final
state leptons
This gives a nice signature to look for.
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The H.E.S.S. data
Expected gamma-ray flux from the galactic center
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Can one see the photon peak?
Bergström, T.B., Eriksson Gustafsson, JCAP 05
As for SUSY, direct annihilation into ?? or Z? is
loop-suppressed.
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Antiprotons from KK dark matter
Expected fluxes are in general too low to be seen

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Antiprotons from KK dark matter
Expected fluxes are in general too low to be seen

Allowing for clumpy halo distributions, however,
PAMELA and AMS will be able to see a
characteristic distortion in the spectrum.
mB(1) 800 GeV, boost-factor 100
T.B. 05
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Neutrinos
In contrast to SUSY, neutrinos are directly
produced in LKP annihilations (branching ratio
4).
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Direct detection
Single nucleon cross sections spin-independent/s
pin-dependent mp/mB(1)
Detection rates spin-independent/spin-dependent
A²
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Upcoming direct-detection experiments
Servant Tait, NJP 02
Ge detectors
Xe detectors
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Conclusions
The LKP appears as a natural dark matter
candidate in the UED model