1,245 research outputs found
UV Completions of Magnetic Inelastic Dark Matter and RayDM for the Fermi Line(s)
Models that seek to produce a line at ~130 GeV as possibly present in the
Fermi data face a number of phenomenological hurdles, not the least of which is
achieving the high cross section into gamma gamma required. A simple
explanation is a fermionic dark matter particle that couples to photons through
loops of charged messengers. We study the size of the dimension 5 dipole (for a
pseudo-Dirac state) and dimension 7 Rayleigh operators in such a model,
including all higher order corrections in 1/M_{mess}. Such corrections tend to
enhance the annihilation rates beyond the naive effective operators. We find
that while freezeout is generally dominated by the dipole, the present day
gamma-ray signatures are dominated by the Rayleigh operator, except at the most
strongly coupled points, motivating a hybrid approach. With this, the Magnetic
inelastic Dark Matter scenario provides a successful explanation of the lines
at only moderately strong coupling. We also consider the pure Majorana WIMP,
where both freezeout and the Fermi lines can be explained, but only at very
strong coupling with light (~200 - 300 GeV) messengers. In both cases there is
no conflict with non-observation of continuum photons.Comment: 11 pages, 6 figure
Addendum to "On an unverified nuclear decay and its role in the DAMA experiment''
We reply to the critiques of our paper arXiv:1210.5501 by the DAMA
collaboration which appeared in arXiv:1210.6199 and arXiv:1211.6346. Our
original claim that the observed background levels are likely to require a
large modulation fraction of any putative signal holds. In fact, in light of
DAMA's recent comment our claim is further corroborated. We identify the source
of the discrepancy between our own analysis and DAMA's claimed levels of
unmodulated background. Our analysis indicates that the background in the
signal region as reported by DAMA is indeed likely underestimated.Comment: 6 pages, 2 figures; replacement of the original reply to
arXiv:1210.6199 to include a response to the second critique in
arXiv:1211.6346. A fit to the unmodulated rate including signal is presented.
No change in the conclusion
On an unverified nuclear decay and its role in the DAMA experiment
The rate of the direct decay of 40K to the ground state of 40Ar through
electron capture has not been experimentally reported. Aside from its inherent
importance for the theory of electron capture as the only such decay known of
its type (unique third-forbidden), this decay presents an irreducible
background in the DAMA experiment. We find that the presence of this
background, as well as others, poses a challenge to any interpretation of the
DAMA results in terms of a Dark Matter model with a small modulation fraction.
A 10ppb contamination of natural potassium requires a 20% modulation fraction
or more. A 20ppb contamination, which is reported as an upper limit by DAMA,
disfavors any Dark Matter origin of the signal. This conclusion is based on the
efficiency of detecting 40K decays as inferred from simulation. We propose
measures to help clarify the situation.Comment: 8 pages, 3 figures; v2 - published version; results unchanged; an
addendum can be found in http://arxiv.org/abs/arXiv:1210.754
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