11 research outputs found
Scalar Bilepton Dark Matter
In this work we show that 3-3-1 model with right-handed neutrinos has a
natural weakly interacting massive particle (WIMP) dark mater candidate. It is
a complex scalar with mass of order of some hundreds of GeV which carries two
units of lepton number, a scalar bilepton. This makes it a very peculiar WIMP,
very distinct from Supersymmetric or Extra-dimension candidates. Besides,
although we have to make some reasonable assumptions concerning the several
parameters in the model, no fine tunning is required in order to get the
correct dark matter abundance. We also analyze the prospects for WIMP direct
detection by considering recent and projected sensitivities for WIMP-nucleon
elastic cross section from CDMS and XENON Collaborations.Comment: 21 pages, 8 figures, uses iopart.cls, same text as published version
with a small different arrangement of figure
Non-Baryonic Dark Matter - Observational Evidence and Detection Methods
The evidence for the existence of dark matter in the universe is reviewed. A
general picture emerges, where both baryonic and non-baryonic dark matter is
needed to explain current observations. In particular, a wealth of
observational information points to the existence of a non-baryonic component,
contributing between around 20 and 40 percent of the critical mass density
needed to make the universe geometrically flat on large scales. In addition, an
even larger contribution from vacuum energy (or cosmological constant) is
indicated by recent observations. To the theoretically favoured particle
candidates for non-baryonic dark matter belong axions, supersymmetric
particles, and of less importance, massive neutrinos. The theoretical
foundation and experimental situation for each of these is reviewed. Direct and
indirect methods for detection of supersymmetric dark matter are described in
some detail. Present experiments are just reaching the required sensitivity to
discover or rule out some of these candidates, and major improvements are
planned over the coming years.Comment: Submitted to Reports on Progress in Physics, 59 pages, LaTeX, iopart
macro, 14 embedded postscript figure
Target dark matter detection rates in models with a well-tempered neutralino
In the post-LEP2 era, and in light of recent measurements of the cosmic
abundance of cold dark matter (CDM) in the universe from WMAP, many
supersymmetric models tend to predict 1. an overabundance of CDM and 2.
pessimistically low rates for direct detection of neutralino dark matter.
However, in models with a ``well-tempered neutralino'', where the neutralino
composition is adjusted to give the measured abundance of CDM, the neutralino
is typically of the mixed bino-wino or mixed bino-higgsino state. Along with
the necessary enhancement to neutralino annihilation rates, these models tend
to give elevated direct detection scattering rates compared to predictions from
SUSY models with universal soft breaking terms. We present neutralino direct
detection cross sections from a variety of models containing a well-tempered
neutralino, and find cross section asymptotes with detectable scattering rates.
These asymptotic rates provide targets that various direct CDM detection
experiments should aim for. In contrast, in models where the neutralino mass
rather than its composition is varied to give the WMAP relic density via either
resonance annihilation or co-annihilation, the neutralino remains essentially
bino-like, and direct detection rates may be below the projected reaches of all
proposed experiments.Comment: 13 pages including 1 EPS figur
Results from a Low-Energy Analysis of the CDMS II Germanium Data
We report results from a reanalysis of data from the Cryogenic Dark Matter
Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken
between October 2006 and September 2008 using eight germanium detectors are
reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased
sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs)
with masses below ~10 GeV/c^2. This analysis provides stronger constraints than
previous CDMS II results for WIMP masses below 9 GeV/c^2 and excludes parameter
space associated with possible low-mass WIMP signals from the DAMA/LIBRA and
CoGeNT experiments.Comment: 9 pages, 8 figures. Supplemental material included as ancillary
files. v3) Added appendix with additional details regarding energy scale and
background
First Direct Limits on Lightly Ionizing Particles with Electric Charge Less than e/6
While the standard model of particle physics does not include free particles with fractional charge, experimental searches have not ruled out their existence. We report results from the Cryogenic Dark Matter Search (CDMS II) experiment that give the first direct-detection limits for cosmogenically produced relativistic particles with electric charge lower than e/6. A search for tracks in the six stacked detectors of each of two of the CDMS II towers finds no candidates, thereby excluding new parameter space for particles with electric charges between e/6 and e/200
Recommended from our members
Results from a low-energy analysis of the CDMS II germanium data.
We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below ∼10  GeV/c(2). This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9  GeV/c(2) and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments
Silicon Detector Dark Matter Results from the Final Exposure of CDMS II
We report results of a search for weakly interacting massive particles (WIMPS) with the silicon detectors of the CDMS II experiment. This blind analysis of 140.2 kg day of data taken between July 2007 and September 2008 revealed three WIMP-candidate events with a surface-event background estimate of 0.41+0.20−0.08(stat)+0.28−0.24(syst). Other known backgrounds from neutrons and Pb206 are limited to <0.13 and <0.08 events at the 90% confidence level, respectively. The exposure of this analysis is equivalent to 23.4 kg day for a recoil energy range of 7–100 keV for a WIMP of mass 10  GeV/c2. The probability that the known backgrounds would produce three or more events in the signal region is 5.4%. A profile likelihood ratio test of the three events that includes the measured recoil energies gives a 0.19% probability for the known-background-only hypothesis when tested against the alternative WIMP+background hypothesis. The highest likelihood occurs for a WIMP mass of 8.6  GeV/c2 and WIMP-nucleon cross section of 1.9×10−41  cm2
Silicon detector results from the first five-tower run of CDMS II
We report results of a search for weakly interacting massive particles (WIMPs) with the Si detectors of the CDMS II experiment. This report describes a blind analysis of the first data taken with CDMS II’s full complement of detectors in 2006–2007; results from this exposure using the Ge detectors have already been presented. We observed no candidate WIMP-scattering events in an exposure of 55.9 kg-days before analysis cuts, with an expected background of ∼1.1 events. The exposure of this analysis is equivalent to 10.3 kg-days over a recoil energy range of 7–100 keV for an ideal Si detector and a WIMP mass of 10  GeV/c 2 . These data set an upper limit of 1.7×10 −41   cm 2 on the WIMP-nucleon spin-independent cross section of a 10  GeV/c 2 WIMP. These data exclude parameter space for spin-independent WIMP-nucleon elastic scattering that is relevant to recent searches for low-mass WIMPs