New twist on excited dark matter: Implications for INTEGRAL, PAMELA/ATIC/PPB-BETS, DAMA
- Physics Department, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)
We show that the 511 keV gamma ray excess observed by INTEGRAL/SPI can be more robustly explained by exciting dark matter (DM) at the center of the galaxy, if there is a peculiar spectrum of DM states {chi}{sub 0}, {chi}{sub 1}, and {chi}{sub 2}, with masses M{sub 0}{approx}500 GeV, M{sub 1} < or approx. M{sub 0}+2m{sub e}, and M{sub 2}=M{sub 1}+{delta}M > or approx. M{sub 0}+2m{sub e}. The small mass splitting {delta}M should be < or approx. 100 keV. In addition, we require at least two new gauge bosons (preferably three), with masses {approx}100 MeV. With this spectrum, {chi}{sub 1} is stable but can be excited to {chi}{sub 2} by low-velocity DM scatterings near the Galactic center, which are Sommerfeld-enhanced by two of the 100 MeV gauge boson exchanges. The excited state {chi}{sub 2} decays to {chi}{sub 0} and nonrelativistic e{sup +}e{sup -}, mediated by the third gauge boson, which mixes with the photon and Z. Although such a small 100 keV splitting has been independently proposed for explaining the DAMA annual modulation through the inelastic DM mechanism, the need for stability of {chi}{sub 1} (and hence sequestering it from the standard model) implies that our scenario cannot account for the DAMA signal. It can, however, address the PAMELA/ATIC positron excess via DM annihilation in the galaxy, and it offers the possibility of a sharper feature in the ATIC spectrum relative to previously proposed models. The data are consistent with three new gauge bosons, whose couplings fit naturally into a broken SU(2) gauge theory where the DM is a triplet of the SU(2). We propose a simple model in which the SU(2) is broken by new Higgs triplet and 5-plet vacuum expectation values, giving rise to the right spectrum of DM and mixing of one of the new gauge bosons with the photon and Z boson. A coupling of the DM to a heavy Z{sup '} may also be necessary to get the right relic density and PAMELA/ATIC signals.
- OSTI ID:
- 21266375
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 79, Issue 6; Other Information: DOI: 10.1103/PhysRevD.79.063530; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BOSON-EXCHANGE MODELS
COSMIC PHOTONS
COUPLING
EXCITED STATES
GALAXIES
GAMMA RADIATION
GAUGE INVARIANCE
GEV RANGE 100-1000
HIGGS BOSONS
HIGGS MODEL
KEV RANGE 100-1000
MEV RANGE 100-1000
NONLUMINOUS MATTER
PARTICLE DECAY
PHOTONS
POSITRONS
STANDARD MODEL
SU-2 GROUPS
SYMMETRY BREAKING
Z NEUTRAL BOSONS