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Testing Dark Matter with neutrino detectors

Testing Dark Matter with neutrino detectors. Melbourne Neutrino Theory Workshop Melbourne (Australia) June 2-4, 2008. Evidences of DM. Rotation curves of galaxies and clusters

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Testing Dark Matter with neutrino detectors

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  1. Testing Dark Matter with neutrino detectors Melbourne Neutrino Theory Workshop Melbourne (Australia) June 2-4, 2008

  2. Evidences of DM Rotation curves of galaxies and clusters Weak modulation of strong lensing, Oort discrepancy, weak gravitational lensing, velocity dispersions of dwarf spheroidal galaxies and of spiral gallaxy satellites… Black-holes, brown dwarfs, white dwarfs, giant planets, neutron stars …? Need non-luminous matter

  3. Cosmological evidences Non-baryonic Dark Matter • WMAP Best-fit for a flat ¤CDM model: mh2 = 0.1326 ± 0.0063 But… bh2 = 0.02229 ±0.00073 NASA / WMPA Science Team, WMAP 5-year results B. D. Fields and S. Sarkar, PDG

  4. Nature of the Dark Matter Standard Model Neutrinos, sterile neutrinos, axions, neutralinos, sneutrinos, gravitinos, axinos, light scalars, from little Higgs models, Kaluza-Klein, super-heavy particles, Q-balls, mirror particles, charged massive particles, self-interacting particles, D-matter, cryptons, superweakly interacting particles, brane world particles, heavy fourth generation neutrinos…

  5. What do we know about Dark Matter? Astrophysicist view: Particle Physicist view:

  6. Detecting DM Direct Detection Nuclear recoil produced by DM elastic scattering Collider Searches Missing energy Indirect Detection Observation of annihilation products Gamma-ray telescopes (MAGIC, CANGAROO-III, HESS, VERITAS, EGRET, GLAST…)‏ Anti-matter experiments (HEAT, BESS, PAMELA…)‏ Neutrino detectors/telescopes (IceCUBE, ANTARES, AMANDA, Super-Kamiokande…)‏

  7. Direct Detection Spin-dependent Spin-independent D. S. Akerib et al. [CDMS Collaboration], Phys. Rev. D73:011102, 2006 G. Angloher et al. [CRESST Collaboration], Astropart. Phys. 23:325, 2005 Z. Ahmed et al. [CDMS Collaboration], arXiv:0802.3530 J. Angle et al. [XENON Collaboration], Phys. Rev. Lett. 100:021303, 2008 H. S. Lee et al. [KIMS Collaboration], Phys. Rev. Lett. 99:091301, 2007 E. Behnke et al. [COUPP Collaboration], Science 319:933, 2008

  8. Some DM properties • DM may acumulate in celestial bodies like the Sun • DM-nucleon elastic cross section sets the normalization • Different annihilation channels imply different ν flux • How big is the annihilation cross section? • For a thermal relic: <σv> ~ 3 x 10-26 cm3/s • But…DM might only exist in the late Universe • <σv> sets the rate of DM annihilation in DM halos • If DM is unstable, how long does it live? • τ would set the rate of DM decay in DM halos Can we test them with neutrino detectors?

  9. Annihilations from the Sun

  10. Indirect Neutrino Detection • WIMPs elastically scatter with the nuclei of celestial bodies to a velocity smaller than the escape velocity, so they remain trapped inside • Additional scatterings give rise to an isothermal distribution • Trapped WIMPs can annihilate into SM particles • After some time, annihilation and capture rates equilibrate • Only neutrinos can escape

  11. Neutrinos from WIMP annihilations Distance source-detector Neutrino spectrum from annihilation channel i Branching ratio into annihilation channel i

  12. Neutrino spectra at detection Need to take into account oscillations and solar absorption M. Cirelli et al., Nucl. Phys. B727:99, 2005

  13. IceCube, ANTARES… Detection of muon events induced by muon neutrinos Counting experiments above some energy threshold

  14. Limits from SK Spin-independent Spin-dependent S. Desai et al., Phys. Rev. D70:083523, 2004

  15. Rates in a Neutrino Telescope F. Halzen and D. Hooper, Phys. Rev. D73:123507, 2006 To get the same rate: trade annihilation channel by cross section

  16. Future Neutrino Detectors Magnetized Iron Calorimeters MINOS-like, INO… Totally Active Scintillator Detectors NOvA, MINERvA… Liquid Argon Time Projection Chamber GLACIER… Very good angular and energy resolution for νe and/or ν¹ for 10’s of GeV → suitable for low mass WIMPs “Small” detectors: only suitable for neutrinos from annihilations in the Sun

  17. Angular and Energy Resolutions for MIND • We take 5 GeV-energy bins • We take the rms spread in the direction between the neutrino and the lepton: T. Abe et al., The ISS Detector Working Group

  18. Neutrino Events ν¹-events νe-events Determination of WIMP mass

  19. mDM = 50 GeV BR¿+¿- (hard) = 20% mDM = 70 GeV BR¿+¿-(hard) = 10% O. Mena, SPR and S. Pascoli, Phys. Lett. B664:92, 2008

  20. Annihilations from the halo

  21. Model-independent bound J. F. Beacom, N. F. Bell and G. D. Mack, Phys. Rev. Lett. 99:231301, 2007 • Neutrinos are the least detectable particles of the SM • From the detection point of view the most conservative assumption (the worst case) is that DM annihilates only into ν’s: Â Â→ νν • This is not an assumption about realistic models • It provides a bound on the total annihilation cross section and not on the partial cross section to neutrinos • Anything else would produce photons, and hence would lead to a stronger limit

  22. Strategy • Calculate neutrino flux: proportional to annihilation cross section and ½DM2 • For E ~ 100 MeV – 100 TeV the main background: atmospheric neutrino flux • Consider angle-averaged flux in wide energy bins • Compare potential signal with the well known and measured background: set upper bound on the DM annihilation cross section

  23. Signal Experiment Particle Physics Astrophysics

  24. Field of View Neutrino Spectrum: Flavor democracy Average of the Line of Sight Integration of ½2

  25. Energy resolution: ¢log E = 0.3 H. Yüksel, S. Horiuchi, J. F. Beacom and S. Ando, Phys. Rev. D76:123506, 2007 Other related limits M. Kachelriess and P. D. Serpico, Phys. Rev. D76:063516, 2007 N. F. Bell, J. B. Dent, T. D. Jacques and T. J. Weiler, arXiv:0805.3423 J. B. Dent, R. J. Scherrer and T. J. Weiler, arXiv:0806.0370 G. D. Mack, T. D. Jacques, J. F. Beacom, N. F. Bell and H. Yüksel, arXiv:0803.0157

  26. Can we do better? Careful treatment of energy resolution and backgrounds: eg. limits on MeV DM We use SK data for E = 18-82 MeV Detection: νe + p → e+ + n Two main backgrounds: Invisible muons Atmospheric neutrinos M. S. Malek, Ph.D thesis M. S. Malek et al., Phys. Rev. Lett. 90:061101, 2003

  27. We perform a similar Â2 analysis as that done by SK to limit the flux of DSNB and we set an upper bound on the DM annihilation cross section SPR and S. Pascoli, Phys. Rev. D77, 025025 (2008) SPR, arXiv:0805.3367

  28. What if this is actually the case and DM only annihilates into neutrinos? C. Boehm, Y. Farzan, T. Hambye, SPR and S. Pascoli, Phys. Rev. D 77, 043516 (2008) LENA: 50000 m3 scintillator after 10 years Reactor BG DSNB Atmospheric BG SPR and S. Pascoli, Phys. Rev. D77, 025025 (2008)

  29. Decays from the halo

  30. Neutrinos are the least detectable particles of the SM From the detection point of view the most conservative assumption is that DM decays only into ν’s : χ → νν Flux proportional to the inverse of the DM lifetime and ρDM For E ~ 100 MeV – 100 TeV the main background: atmospheric neutrino flux Compare potential signal with the well known and measured background: set lower bound on the DM lifetime

  31. Signal Experiment Particle Physics Astrophysics

  32. Field of View Neutrino Spectrum: Flavor democracy Average of the Line of Sight Integration of ρ

  33. Using SK data from DSNB search: Detailed analysis of background and energy resolution New model-independent bound from CMB and SN observations Model-independent bound from CMB observations SPR, arXiv:0712.1937 to be published in Phys. Lett. B Y. Gong and X. Chen, arXiv:0802.2296 K. Ichiki, M. Oguri and K. Takahashi, Phys. Rev. Lett. 93, 071302 (2004)

  34. Conclusions Neutrino detectors can test DM properties Searches for neutrinos from DM annihilations/decays in celestial bodies could constitute powerful probes of DM properties Cherenkov neutrino detectors/telescopes are counting experiments and could only provide limited information Future neutrino detectors (MIND, TASD and LArTPC) will have very good energy resolution for 10’s GeV Reconstructing the neutrino spectra → information on DM mass, annihilation branching ratios and DM-proton cross section Due to small size, only suitable for large spin-dependent cross sections and neutrinos from annihilations in the Sun, but complementary to Neutrino Telescopes (with higher threshold)‏ Neutrino detectors can set model-independent bounds on the DM annihilation cross section and on the DM lifetime Future detectors (LENA) might be able to detect a signal from DM annihilations/decay

  35. The world is full of obvious things which nobody by any chance ever observes When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth Sherlock Holmes

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