1,629 research outputs found
New results from DAMA/LIBRA
DAMA/LIBRA is running at the Gran Sasso National Laboratory of the I.N.F.N..
Here the results obtained with a further exposure of 0.34 ton x yr are
presented. They refer to two further annual cycles collected one before and one
after the first DAMA/LIBRA upgrade occurred on September/October 2008. The
cumulative exposure with those previously released by the former DAMA/NaI and
by DAMA/LIBRA is now 1.17 ton x yr, corresponding to 13 annual cycles. The data
further confirm the model independent evidence of the presence of Dark Matter
(DM) particles in the galactic halo on the basis of the DM annual modulation
signature (8.9 sigma C.L. for the cumulative exposure). In particular, with the
cumulative exposure the modulation amplitude of the single-hit events in the (2
-- 6) keV energy interval measured in NaI(Tl) target is (0.0116 +- 0.0013)
cpd/kg/keV; the measured phase is (146 +- 7) days and the measured period is
(0.999 +- 0.002) yr, values well in agreement with those expected for the DM
particles.Comment: presented at the Int. Conf. Beyond the Standard Models of Particle
Physics, Cosmology and Astrophysics (BEYOND 2010), 1-6 February 2010, Cape
Town, South Afric
Technical aspects in dark matter investigations
Some theoretical and experimental aspects regarding the direct dark matter
field are mentioned. In particular some arguments, which play a relevant role
in the evaluation of model dependent interpretations of experimental results
and in comparisons, are shortly addressed.Comment: Proceedings of TAUP 2011 Conferenc
Direct Detection of Non-Chiral Dark Matter
Direct detection experiments rule out fermion dark matter that is a chiral
representation of the electroweak gauge group. Non-chiral real, complex and
singlet representations, however, provide viable fermion dark matter
candidates. Although any one of these candidates will be virtually impossible
to detect at the LHC, it is shown that they may be detected at future planned
direct detection experiments. For the real case, an irreducible radiative
coupling to quarks may allow a detection. The complex case in general has an
experimentally ruled out tree-level coupling to quarks via Z-boson exchange.
However, in the case of two SU(2)_L doublets, a higher dimensional coupling to
the Higgs can suppress this coupling, and a remaining irreducible radiative
coupling may allow a detection. Singlet dark matter could be detected through a
coupling to quarks via Higgs exchange. Since all non-chiral dark matter can
have a coupling to the Higgs, at least some of its mass can be obtained from
electroweak symmetry breaking, and this mass is a useful characterization of
its direct detection cross-section.Comment: 22 pages, 3 figures. References added. Minor corrections to match
published versio
A comprehensive analysis of the dark matter direct detection experiments in the mirror dark matter framework
Mirror dark matter offers a framework to explain the existing dark matter
direct detection experiments. Here we confront this theory with the most recent
experimental data, paying attention to the various known systematic
uncertainties, in quenching factor, detector resolution, galactic rotational
velocity and velocity dispersion. We perform a detailed analysis of the DAMA
and CoGeNT experiments assuming a negligible channeling fraction and find that
the data can be fully explained within the mirror dark matter framework. We
also show that the mirror dark matter candidate can explain recent data from
the CDMS/Ge, EdelweissII and CRESSTII experiments and we point out ways in
which the theory can be further tested in the near future.Comment: about 30 page
Light Neutralinos and WIMP direct searches
The predictions of our previous analyses about possible low-mass (lower than
50 GeV) relic neutralinos are discussed in the light of the most recent results
from WIMP direct detection experiments. It is proved that these light
neutralinos are quite compatible with the new annual-modulation data of the
DAMA Collaboration; our theoretical predictions are also compared with the
upper bounds of the CDMS and EDELWEISS Collaborations.Comment: 4 pages, 1 figures, typeset with ReVTeX4. The paper may also be found
at http://www.to.infn.it/~fornengo/papers/note.ps.gz or through
http://www.to.infn.it/astropart/index.htm
WIMPs search by scintillators: possible strategy for annual modulation search with large-mass highly-radiopure NaI(Tl)
The DAMA experiments are running deep underground in the Gran Sasso National
Laboratory. Several interesting results have been achieved so far. Here a
maximum likelihood method to search for the WIMP annual modulation signature is
discussed and applied to a set of preliminary test data collected with large
mass highly radiopure NaI(Tl) detectors. Various related technical arguments
are briefly addressed.Comment: 6 pages, 4 figures, LaTex. Contributed paper to TAUP97; to appear in
the Proceeding
Possible implications of the channeling effect in NaI(Tl) crystals
The channeling effect of low energy ions along the crystallographic axes and
planes of NaI(Tl) crystals is discussed in the framework of corollary
investigations on WIMP Dark Matter candidates. In fact, the modeling of this
existing effect implies a more complex evaluation of the luminosity yield for
low energy recoiling Na and I ions. In the present paper related
phenomenological arguments are developed and possible implications are
discussed at some extent.Comment: 16 pages, 10 figures, preprint ROM2F/2007/15, submitted for
publicatio
Generalized Analysis of Weakly-Interacting Massive Particle Searches
We perform a generalized analysis of data from WIMP search experiments for
point-like WIMPs of arbitrary spin and general Lorenz-invariant WIMP-nucleus
interaction. We show that in the non-relativistic limit only spin-independent
(SI) and spin-dependent (SD) WIMP-nucleon interactions survive, which can be
parameterized by only five independent parameters. We explore this
five-dimensional parameter space to determine whether the annual modulation
observed in the DAMA experiment can be consistent with all other experiments.
The pure SI interaction is ruled out except for very small region of parameter
space with the WIMP mass close to 50 GeV and the ratio of the WIMP-neutron to
WIMP-proton SI couplings . For the predominantly SD
interaction, we find an upper limit to the WIMP mass of about 18 GeV, which can
only be weakened if the constraint stemming from null searches for energetic
neutrinos from WIMP annihilation the Sun is evaded. None of the regions of the
parameter space that can reconcile all WIMP search results can be easily
accommodated in the minimal supersymmetric extension of the standard model.Comment: 27 pages, 3 figure
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