Enhancement of Dark Matter Annihilation via BreitWigner Resonance

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Enhancement of Dark Matter Annihilation via
Breit-Wigner Resonance
W.L. Guo and Y.L. Wu, PRD 79,055012 (2009)
arXiv0901.1450

• ???
• Institute of Theoretical Physics, CAS

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Outline

• Evidences for dark matter
• PAMELA and ATIC anomalies
• Theoretical explanation
• Large Boost factor
• Annihilate into charged leptons
• The Breit-Wigner Enhancement
• Discussion and Summary

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The galactic scale

• Since 1975, Vera Rubin started to notice FLAT
  rotation curves in spiral galaxies.

Newtonian dynamics
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The scale of galaxy clusters
(1) Measure the velocity of galaxies in clusters
The first indication for dark matter is made by
Fritz Zwicky in 1933.
(2) The X-rays trace the hot gas
(3) The gravitational lensing

• Strong lensing
• Weak lensing
• Microlensing

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The Bullet Cluster
Dark Matter coincides with galaxies Both (nearly)
collisionless Gas separated from Dark
Matter Inelastic collision
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Dark Matter Ring
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The cosmological scale
(1) Large scale structure
(2) CMB
Current results
WMAP 5
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Alternatives to Dark Matter
Modified Newton Dynamics (MOND)
Density fluctuation 10-3
Bullet clusters
By M. Turner
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Dark matter candidates
The non-baryonic dark matter candidates should
satisfy the following 3 conditions

• Stable or the life is very long
• Do not interact with photon
• Produce the correct relic density

Model building
Dark matter candidate is always accompanied with
some discrete symmetries which keep it stable!
(Such as the R, KK and T parities)
In the LR symmetric model, P and CP can make the
DM stability. On the other hand, we can realize
the spontaneous CP violation.
W.L. Guo, L.M. Wang, Y.L. Wu, Y.F. Zhou and C.
Zhuang, PRD 79, 055015 (2009) arXiv0811.2556
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Dark matter searches
(1) Collider search
(2) Direct search
(3) Indirect search
Annihilation productions Gamma rays, Neutrinos,
electrons, Positrons Protons and antiprotons etc.
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PAMELA Positron fraction

• Payload for Antimatter Matter Exploration and
  Light Nuclei Astrophysics
• Satellite Launch 15/06/06

Positron fraction
arXiv 0810.4995
The positron fraction have an excess from
10-100GeV
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PAMELA Antiproton/ Proton
Antiproton/ Proton
arXiv 0810.4994
Z2
There is no excess for the antiproton!
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Two balloon experiments ATIC and PPB-BETS
J. Chang et al., Nature 456, 362, (2008)
S. Torii et al., arXiv 0809.0760
ATIC and PPB-BETS
-
Have also seen the excess in the e e energy
spectrum between 300 800 GeV
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Explanations for PAMELA, ATIC and PPB-BETS
Astrophysical sources

• Pulsars (0810.1527 0810.27840812.4457)
• Gamma-ray bursts or microquasars (0812.4851)
• Supernova remnant (0902.0376)
• CRs interaction (0901.1520)

Dark matter

• DM annihilation
• DM decay

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Dark Matter
Diffusion equation for positron
Space Energy Source
Result of the above equation
variables
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General analysis
A. Strumia et al., arXiv 0809.2409
P. F. Yin et al., arXiv 0811.0176
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P. F. Yin et al., arXiv 0811.0176
DM mass m 1 TeV Have two puzzles

• Dominantly annihilate into charged leptons
• Need an enough large boost factor (100 1000)

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Solving the two puzzles
1? Boost factor
2? Lepton final states
Symmetry 0811.03990902.0814 Kinetic0810.07130
810.1502 0810.5397
Two ways
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Boost Factor puzzle
The only difference is the temperature xm/T or
velocity
Usually ltsigma vgt may be expanded in powers of
x-1
If lt sigma vgt is inverse proportion v (klt0), we
can obtain larger lt sigma vgt in the current
halo. gt Solving the boost factor puzzle!
The Breit-Wigner enhancement can realize this
scenario !
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Thermally averaged annihilation cross section
S-channel Resonance
In the galactic halo, DM particles are usually
assumed to follow a Maxwell -Boltzmann
distribution
We can safely use the above equation to calculate
the ltsigma vgt!
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A Example for Breit-Wigner Enhancement
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The evolution behavior of the Breit-Wigner
enhanced
The Approximate Formula
The Exact Formula
The evolution behavior
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Numerical results
Using the exact formulas
General conclusions
V0.001
V0.02
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The Exact Boost Factor
Boltzmann Equation
X.J. Bi et al
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Boost factor and Couplings
Taking m 1 TeV
If m is enlarged by N times, alpha or BiBf should
be approximately enlarged N2 times!
We would like to emphasize that the boost factor
is insensitive to m!
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Discussions
For the same DM mass m1 TeV, if alpha2 or BiBf
is enlarged by N times
DM relic number density Y will be suppressed by
the same times. This scenario will give the
smaller DM annihilation rate, which is
proportional to ltsigma vgt Y2 .
If annihilation includes non-resonance and
resonance cases, and the non-resonance case
determine the relic density
We can not obtain the coupling alpha or BiBf from
the relic density. Alpha or BiBf must be smaller
than the predicted values. It is still have
parameter space to give the required ltsigma vgt.
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Summary

• PAMELA has reported an excess in the positron
  factor from 10100 GeV, but shown no excess for
  antiproton
• ATIC and PPB-BETS have also seen the excess in
  the e and e- energy spectrum between 300-800
  GeV
• DM annihilation can explain the PAMELA, ATIC and
  PPB-BETS anomalies.
• Large Boost factor
• Annihilate into charged leptons
• The Breit-Wigner Enhancement can provide an
  enough large boost factor BF gt 100 to explain
  these anomalies.

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Thanks!