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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.

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Celine Bœhm, Moriond ElectroWeak 2005

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  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

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