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Dark Matter Annihilation/Decay Scenarios

Dark Matter Annihilation/Decay Scenarios. Novel Searches for Dark Matter with Neutrino Telescopes Columbus, OH (USA) November 17-19, 2008. What do we know about Dark Matter?. Astrophysicist view: Particle Physicist view:. Annihilations/Decays from the halo.

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Dark Matter Annihilation/Decay Scenarios

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  1. Dark Matter Annihilation/DecayScenarios Novel Searches for Dark Matter with Neutrino Telescopes Columbus, OH (USA) November 17-19, 2008

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

  3. Annihilations/Decays from the halo

  4. J. F. Beacom, N. F. Bell and G. D. Mack, Phys. Rev. Lett. 99:231301, 2007 Model-independent bound • 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 (decays) only into ν’s: Â Â→ νν (Â→ νν) • This is not an assumption about realistic models • It provides a bound on the total annihilation cross section (lifetime) and not on the partial cross section (lifetime) to neutrinos • Anything else would produce photons, and hence would lead to a stronger limit

  5. Strategy Two energy regions: backgrounds • Calculate neutrino flux • Compare potential signal with the background • E ~ 100 MeV – 100 TeV: atmospheric neutrino flux • E ~ 10 MeV – 100 MeV: invisible muons and atmospheric neutrino flux

  6. Signal from Annihilations Experiment Particle Physics Astrophysics

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

  8. Signal from Decays Experiment Particle Physics Astrophysics

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

  10. Annihilations vs Decays • 2 DM particles • E = m • Proportional to <¾v>/mÂ2 • Proportional to ½2 • 1 DM particle • E = mÂ/2 • Proportional to 1/¿Âm • Proportional to ½

  11. Annihilations: DM Density Profile Uncertainties SPR and S. Pascoli, Phys. Rev. D77:025025, 2008 • Local rotational velocity • Amount of flatness • Non-halo components From the allowed range of: P. Belli et al., Phys.Rev.D 66:043503, 2002 Decays: Extreme values for the 3 profiles: Javg = (1.3, 8.1) SPR, Phys. Lett. B665:50, 2008

  12. 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, Phys. Rev. D78:083540, 2008 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, Phys. Rev. D78:063542, 2008

  13. 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

  14. 16 4-MeV bins in the range [18,82] MeV Nl = Number of events in bin l Al = fraction of signal events Bl = fraction of Michel electrons (positrons) Cl = fraction of atmospheric electron (anti)neutrinos Analysis

  15. Annihilations: 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

  16. 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

  17. Decays: Using SK data from DSNB search: Detailed analysis of background and energy resolution SPR, Phys. Lett. B665:50, 2008 New model-independent bound from CMB and SN observations Model-independent bound from CMB observations For γ-line limits: Y. Gong and X. Chen, Phys. Rev. D77:103511, 2008 H. Yuksel and M. Kistler, Phys. Rev. D78:023502, 2008 K. Ichiki, M. Oguri and K. Takahashi, Phys. Rev. Lett. 93:071302, 2004

  18. A few words on PAMELA O. Adriani et al., arXiv:0810.4994 O. Adriani et al., arXiv:0810.4995 Annihilations: need of large boost factors Sub-structure Sommerfeld enhancement Non-thermal production M. Cirelli, M. Kadastik, M. Raidal and A. Strumia, arXiv:0809.2409 Decays: no need of boost factors -> “short” lifetime

  19. Conclusions • Neutrino detectors can test DM properties • Searches for neutrinos from DM annihilations/decays in the galactic halo could constitute powerful probes of DM properties • Neutrino detectors can set model-independent bounds on the DM annihilation cross section and on the DM lifetime • Difficult to distinguish annihilation/decay scenarios: use angular information • Future detectors (LENA) might be able to detect a signal from DM annihilations/decay

  20. 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 Long arm looking for a fingerprinttrying to find the mystery clue Bon Scott

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