Indirect DM Search: Current Status and Report
- 2. Neutrino flux from DM in the Sun ● The neutrino flux from DM annihilation in the Sun is given by: ● The is related to the DM particle property: σχp, the DM-nucleon cross section ● Spectrum dN/dE can be generated by WimpSim Total annihilation rate Neutrino spectrum @ solar core JCAP 08, 021 (2008)
- 3. How evolves? ● The DM number evolution equation in the Sun ● The solution: Self-interaction Self-interaction induced evaporation Gravitational capture Evaporation Annihilation
- 4. Gravitational capture ● DM particles in the Halo attracted by solar gravity therefore scatter with nucleus and captured ● Two types of DM-nucleus interaction: 1) spin-dependent and 2) spin-independent G
- 5. DM capture rate ● Spin-dependent: ● Spin-independent: Phys.Rept. 267, 195 (1996) Phys.Rept. 405, 279 (2005)
- 6. DM capture rate arXiv:1312.6048 σχp = 1 pb σχp = 1 pb
- 7. Evaporation ● The captured DM particles scattered with the nucleus in the Sun and gains kinetic energy thus escapes
- 8. DM evaporation rate ● The evaporation rate: Ce σχp = 10−4 pb Left is for spin-dependent and spin-independent is similar. JCAP 07, 010 (2013) Astrophys. J. 321, 560 (1987) Nucl. Phys. B 283, 681 (1987)
- 9. Self-interaction, S.I. ● The Halo DM particles scatter with the DM already captured by the Sun ● Both captured ● One captured, the other escapes ● Both escapes (self-eject) PRD 80, 063501 (2009)
- 10. S.I. induced evaporation ● It's not one of the three situations mentioned before ● Explored by no one before as far as we know
- 11. DM number inside the Sun Y.-H. Lin, Talk@ICHEP 2014
- 12. Total annihilation rate ● directly matters to the ν signal ● Actually not only related to σχp also σχχ Y.-H. Lin, Talk@ICHEP 2014
- 13. Event rate estimation ● The neutrino event rate can be estimated: Detector effective area We used IC-PINGU's to calculate Detector effective volume νe νμ arXiv:1401.2046 Mton Mton
- 14. Let's have a look @ ● With mχ > 5 GeV, the evaporation mass ● The most popular channels examined are: τ, ν, W...etc. Hard channel Soft channel High energy neutrino from annihilation/decay producthighest fewest C. Rott, Talk@CosPA 2013 Disfavored by current galactic constraints See review article arXiv:1202.1454 for further details
- 15. We expected... ● JUNO detector has ~ 20 kton effective volume ● By examining the hard spectrum ● We can expect the JUNO σχp-sensitivity by projecting the results from PRD 84, 036007 (2011)
- 16. Unfortunately... ● Evaporation occurs while ● Current galactic constraints favor leptophillic dominant channels, but they are not realistic ● The JUNO effective volume is not such large @ GeV level ● JUNO detector is designed to have better performance @ MeV level IceCube JUNO Effective voume 3-5 Mton <20 kton Sensitive flavor All Event rate (yr-1 ) ~7000 (Cas+Tra) <2 Around Eν ~ GeV If JUNO is capable running @ GeV constantly all year
- 17. Soft spectrum revisited ● So far, the problems raised when we focus on hard spectrum signal ● How about soft spectrum? Is it really non-detectable @ detector? ? 1 GeV 100 GeV Soft HardRecently... MeVPRD 34,2206(1986) Nucl.Phys.B304,877(1987) Considered as non-detectable
- 18. Pion multiplication Hadrons Bf = 64.79% Goes to hard spectrum Solar core Annu.Rev.Nucl.Sci. 23, 395 (1973) if survives Continuous hadronic interaction in the medium and energy loss Pion decay at rest Eν up to 52.8 MeV Coulomb absorp- tion, no contribu- tion negligible contribution Pionstoppingpoint Low energy neutrino from hadronic shower
- 19. Pion yield Pion yield at the production point as a function of DM mass mχ JCAP 08, 011 (2013)
- 20. ν-yield from π multiplication PRD 88, 055005 (2013)JCAP 08, 011 (2013)
- 21. ν-yield @ Solar core ● Taking mχ = 10 GeV to avoid evaporation ● Examining spectra from b and τ channels ● Higher mχ is achievable→Severe attenuation happens @ TeV arXiv:1312.6048 Disadvantage to ICDC No affect to MeV ν-yield: Advantage to JUNO
- 22. ν-yield @ JUNO ● Settings are the same as previous: ν-yield per annihilation Soft spectrum 10 - 100 MeV Hard spectrum 1 - 10 GeV Hard spectrum 1 - 10 GeV Soft spectrum 10 - 100 MeV arXiv:1312.6048
- 23. Event rate re-estimation ● The high ν-yield is now @ MeV range ● Thus: ● ν cross section can be approximated as: ● We can estimate the event rate in JUNO per year with (no S.I.): 10 MeV 100 MeV PRD 60, 053003 (1999) Phys.Lett.B 564, 42 (2003) PRD 88, 055005 (2013) ~0.39 yr-1
- 24. Current status ● The soft spectrum has high ν-yield ● MeV neutrinos produced via DM-DM annihila- tion is potentially detectable in JUNO ● At MeV energy, JUNO has maximum effective volume ● We estimated the neutrino event rate per year in JUNO ● By the unique spectrum shape, we can further examine different DM scenarios
- 25. Further steps and discussions ● ν cross section is approximated not exactly calculated or from fine MC simulation ● Event rate is just a rough estimation, careful calculation required ● Backgrounds ● Angular/energy resolutions ● Day/night effects ● Manuscript not updated yet!!! ● …… ● Stay tuned! Haven't analyzed yet!!!