1. Dark Matter direct and indirect detection
Martti Raidal
NICPB, Tallinn, Estonia
NORDITA Winer School 2015

2. We are experiencing very interesting period in fundamental physics –
there are paradigm shifts in several fields
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3. Instead of introduction:
A lesson from the LHC
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4. LHC discovered the Higgs boson
Frascati, 2014

5. All LHC + Tevatron data - 10σ signal
P. Giardino, K. Kannike, I. Masina, M. Raidal, A. Strumia,
arXiv:
Frascati, 2014

6. Tests of Higgs couplings
Frascati, 2014

7. New physics enters only in loops
Frascati, 2014

8. At the same time …. LHC: Precision physics and flavour physics:
No SUSY discovered yet
No signals of compositness, no new resonances
No extra dimensions
No unexpected results
Precision physics and flavour physics:
No new sources of flavour and CP violation
No higher dim. operators below TeV
Frascati, 2014

9. This is exactly opposite to the expectations by naturalness:
All scalar masses must be at cutoff scale …
… unless there exists a stabilizing mechanism at EW scale
… or Nature is fine tuned
Frascati, 2014

10. The hierarchy problem is properly named:
it is not the "quadratic divergence problem”
It concerns the physical hierarchy of
physical particles
Naturalness is a real, physical principle for NP
Frascati, 2014

11. Physics is experimental science!
The lesson
Physics is experimental science!
No SUSY seems to be around the corner
Higgs indicates no GUTs
Community is polarized in rethinking naturalness
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12. Dark Matter comes to rescue!
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13. Outline of my lectures Dark Matter – the evidence
Dark Matter candidates
Ways to detect Dark Matter – direct, indirect, colliders, dark matter self-interactions
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14. History of DM Movement of stars in the Galaxy Movement of galaxies
Jan Oort (1932)
Fritz Zwicky (1933)
Movement of stars
in the Galaxy
Movement of galaxies
in clusters
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15. Evidences for DM Small scale (galactic sizes/distances)
Medium scale (galaxy clusters)
Large scale (observable Universe)
DM is dark because it is seen only through its gravitational interaction. No interaction with SM seen so far!
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16. Small scale - rotation curves of galaxies
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17. Medium scale – galaxy clusters
Velocity dispersion of galaxies in clusters
Gravitational lensing
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18. Medium scale – bullet clusters
Kills MOND, constrains DM self-interactions
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19. Large scale Cosmic Microwave Background (CMB) anisotropies
Large Scale Structure (LSS)
Baryon Acoustic Oscillations (BAO)
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20. The history of Universe
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21. Anisotropies in the Cosmic Microwave Background
The ESA Planck
satellite
Fluctuations 10-5
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22. CMB tells the content of the Universe
The first peak – overall mass-energy content Ω
The second peak – baryonic matter Ωb
The third peak – cold Dark Matter ΩDM
The Universe can be described with ΛCDM
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23. Energy budget of the Universe
Also SN observations confirm the accelerated
expansion of the Universe
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24. CMB polarization
Induced by Thomson scattering at the end of recombination – very small effect
Consistency check for inflation
Planck Mission polarization data must come out these days!
The rumor is …..
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25. Two types of polarization – E-modes and B-modes!
BICEP2 claims to measure primordial B-modes
Fluctuations of gravity
Gravitational lensing (excluded)
Can also be induced by dust
Assuming the first, the measured tensor-to-scalar ratio r=0.2 implies the scale of inflation to be 1016GeV
This is our only realistic exp. test of quantum nature of gravity
Frascati, 2014

26. Tension with Planck data
Frascati, 2014

27. Implications for inflation and gravity?
V=(1016)4 GeV4 is sub-Planckian – particle physics is under control
But Lyth bound implies trans-Planckian field excursions
What about operators like
ϕ6, ϕ48, ϕ which all must
be there according to standard paradigm?
Inflation data shows no trans-Planckian operators!
Frascati, 2014

28. Planck published first dust data
The BICEP2 signal strength can be explained with
r=0.2 and no dust
R=0 and dust only
Frascati, 2014

29. One needs to study correlations between the BICEP2 and dust maps
Done by theorists
Small but significant
correlation found
r=0.1±0.04
This analyses must be
repeated by experiments
Frascati, 2014

30. Large scale - BAO Matter distribution has a preferred scale
Acoustic peak depends
on DM and baryon
content
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31. Large Scale Structure Primordial fluctuations are seeds of structure
Structure formation happens dimension by dimension
Structure has fractal properties – it repeats itself in different scales
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32. DM in galaxies - where is it?
DM halos are believed to be spherical (cannot loose energy)
N-body simulations suggest rich sub-halo content (satellite and dwarf galaxies observed)
Detection of DM depends on mass distribution and minimal mass of subhalos
Detection of DM depends on DM halo properties around Sun
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33. DM density profiles in galaxies
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34. Non-relativistic DM velocity distribution
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35. Problems/challenges/future work
Core vs. cusp problem - N-body simulations prefer cuspy profiles (NFW, Einasto)
“Missing” satellites compared to N-body sim.
“Too big to fail” – satellites less massive than sim.
DM self-interactions?
Planes of satellites in the Galaxy
Bulge-less disc galaxies
Voids too empty?
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36. Example – core vs cusp problem
Density profile in dwarfs seems to have a core
Problem of physics or obs./sim.?
Baryonic matter dominates
in the Galactic centre
DM self-interactions, warm DM?
Solutions:
GAIA satellite will measure movement of stars in our Galaxy and in dwarf satellite galaxies!
N-body simulations become realistic (baryons, DM self)
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37. What is the Dark Matter?
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38. What is the DM mass scale?
Whatever is DM, it couples to gravity via Tμν
The SM does not have
viable cold DM candidate!
The SM neutrinos
with Σ mi=0.1 eV contribute 0.2% of DM
The SM neutrinos are
warm DM
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39. Supermassive objects - MACHOs
Dead stars, planets etc., must be
non-baryonic or created before BBN
Microlensing: MACHO fraction <20% for M=M
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40. Primordial Black Holes (PBH)
Not predicted by standard cosmology
because of small primordial perturbations
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41. DM as elementary particles
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42. DM as a thermal relic
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43. The WIMP miracle This mass scale has nothing to do with EWSB
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44. Warning – many alternatives possible
DM stabilized by Z3 not Z2
semi-annihilations
Freeze-in of very weakly coupled particle
very heavy DM possible
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45. Asymmetric DM DM may be like proton The asymmetries in the
baryon and DM sectors
may be related
Scenarios contain dark forces and selfinteractions
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46. Paradigm shift in WIMP DM physics
Instead of Z2-stabilized one thermal relic (SUSY)
Dark sector can be as complicated as visible sector
Multi-component DM
Dark sector can contain dark forces
Dark photons
Dark Yukawa sector
Strong interactions in the dark sector – Dark Techicolor
Dark Matter can form dark discs (10% of DM in our Galaxy) and/or affect large scale structure
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47. DM mass scale
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48. Ultralight scalars: axion-like particles (ALPs)
If scalar is light, its phase space density is high
Such a DM should be described as a field
To be viable DM, particles must be created at rest
Initial misalignment mechanism
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49. The QCD axion Pseudo-Goldstone boson of axial symmetry
Invented to explain the absence of strong
CP violation
Axions solve the strong CP problem
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50. QCD axion couplings
Couples to gluons and photons due to mixing with the pion
where
Other possible interactions
1 MHz ≈ 4×10-9 eV
nucleon dipole moment d = gda

51. Detection principle Look for axion-photon conversion
From cosmological sources
Create your own - laser
ADMX
Res. microwave cavity
CAST
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52.
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53. Experiments: light-through a wall
Photons „tunnel“ through a barrier via conversion to axions in a strong magnetic field

55. Nucleon electric dipole moment
Given that
DM is a classical field a
that couples to nucleons as
then all (local) nucleons will have a time dependent EDM (current bound |dn| < 2.9×10−26 e·cm)
In the case of the QCD axion
(Molecular EDMs are about 28 orders of magnitude larger.)

56. Expected CASPER sensitivity

57. The message
New experiments are being planned to test light dark sector properties (APLs, dark photons etc.)
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