1 / 18

Celine Bœhm, Moriond ElectroWeak 2005

Light Dark Matter particles. Possible detection in particle physics experiments?. Celine Bœhm, Moriond ElectroWeak 2005. New physics by INTEGRAL/SPI?. 1. Detection of a 511 keV emission line in the centre of the Milky Way. Explanation: electron-positron annihilation.

gili
Download Presentation

Celine Bœhm, Moriond ElectroWeak 2005

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Light Dark Matter particles Possible detection in particle physics experiments? Celine Bœhm, Moriond ElectroWeak 2005

  2. New physics by INTEGRAL/SPI? 1. Detection of a 511 keV emission line in the centre of the Milky Way Explanation: electron-positron annihilation 2. Possible explanations: Supernovae, Wolf-Rayet stars, Low Mass Binaries, …, Dark Matter Celine Bœhm, Moriond ElectroWeak 2005

  3. r~33deg Large exposure data but: the Bulge is where most of the signal comes from Problem faced by SN, Wolf Rayet stars etc (except LMB, DM): the ratio bulge-to-disk is generally not large enough Celine Bœhm, Moriond ElectroWeak 2005

  4. 1. Results from a model fitting analysis (modelling the source) 1e-3 ph/cm2/s FWHM ~ 8.5deg 2. DM must fit both the FWHM, the flux and the ratio bulge-to-disk Celine Bœhm, Moriond ElectroWeak 2005

  5. DM has a ratio bulge/disk compatible with observations DM annihilations into e+ e- can produce the galactic positrons • The positrons must be almost at rest • They must lose their energy through ionization • Once at rest, they form positronium and produce 2 or 3 photons This requires mDM < 100 MeV (i.e. very light DM particles). Celine Bœhm, Moriond ElectroWeak 2005

  6. A. How light DM can be ? (Astrophysics) Annihilations in the centre produce too much low energy gamma rays. (Boehm, Ensslin, Silk, 2002) Solution: The annihilation cross section must vary with time for mdm< 100 MeV. Particle Physics requirement: The annihilation cross section must be dominated by a velocity-dependent Celine Bœhm, Moriond ElectroWeak 2005

  7. B. How light DM can be ? (Particle Physics) • Lee-Weinberg: If DM is afermionand coupled toheavyparticles (Z, W) then it should beheavier than a few GeV. • Boehm-Fayet: If DM is afermionand coupled tolightparticles then it can belighter than a few GeV. If DM is ascalarand coupled tolightorheavyparticles then it can belighter than a few GeV. Celine Bœhm, Moriond ElectroWeak 2005

  8. Interpretation: • Light scalars (Boehm&Fayet, 2003): coupled to heavy particles (F): v-independent cross section coupled to light particles (Z’): v-dependent cross section • Light fermions (Fayet 2004): coupled to light particles (Z’): v-dependent cross section Z’ are required to escape the Gamma ray constraints Celine Bœhm, Moriond ElectroWeak 2005

  9. First Results • Flux OK with observations: • the cross section must be about five order of magnitude • lower than the annihilation cross section for the relic density • Z’ favoured! • Halo density profile: Assumptions: 1/rg as MW halo profile is still unknown Celine Bœhm, Moriond ElectroWeak 2005

  10. New Results: • taking into account more data (16 deg) Boehm&Ascasibar, 2004 • Implementation of the right velocity dispersion profile Celine Bœhm, Moriond ElectroWeak 2005

  11. New and Preliminary Results: • Implementation of the e+ distribution for realistic halo profiles • (NFW, Moore, Binney-Evans, Isothermal) in INTEGRAL analysis • (the source!) • Implementation of the right velocity dispersion profile • More data, including Dec 2004 Celine Bœhm, Moriond ElectroWeak 2005

  12. New results obtained in collaboration with INTEGRAL Celine Bœhm, Moriond ElectroWeak 2005

  13. Consequences: • NFW profile is THE profile that fits the data! • Exchange of heavy particles is needed to fit the 511 keV line For mF ~100 GeV For mF ~1 TeV Celine Bœhm, Moriond ElectroWeak 2005

  14. Fermionic DM seems to be excluded: • Decaying DM is excluded (unless ??? the profile is extremely cuspy): Celine Bœhm, Moriond ElectroWeak 2005

  15. Consequences for Particle Physics S. Davidson et al • NuTeV • Alpha value (anomalous magnetic moment of the electron) Celine Bœhm, Moriond ElectroWeak 2005

  16. Note on Beacom et al, 2004 Mdm < 20 MeV because of the Final State Radiation • But they do not compute the process. • They use the result of e+ e- into mu+ mu- valid for gamma exchange which is factorizable. • However, the F exchange is not factorizable. • The final result could change! Celine Bœhm, Moriond ElectroWeak 2005

  17. Conclusions • NFW profile (consequences for the MW profile if LDM exists) • Scalar DM • Fermionic and decaying DM are ruled out • Heavy fermions are required but Z’ exchange possible too • Look like SUSY but relationship between the couplings and MF, • Possible implication for NuTeV and the alpha value Celine Bœhm, Moriond ElectroWeak 2005

  18. J. Kn¨odlseder et al.: SPI/INTEGRAL constraints on the morphology of the galactic 511 keV line emission

More Related