1,790 research outputs found
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
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
Phenomenology of light neutralinos in view of recent results at the CERN Large Hadron Collider
We review the status of the phenomenology of light neutralinos in an
effective Minimal Supersymmetric extension of the Standard Model (MSSM) at the
electroweak scale, in light of new results obtained at the CERN Large Hadron
Collider. First we consider the impact of the new data obtained by the CMS
Collaboration on the search for the Higgs boson decay into a tau pair, and by
the CMS and LHCb Collaborations on the branching ratio for the decay . Then we examine the possible implications
of the excess of events found by the ATLAS and CMS Collaborations in a search
for a SM--like Higgs boson around a mass of 126 GeV, with a most likely mass
region (95% CL) restricted to 115.5--131 GeV (global statistical significance
about 2.3 ). From the first set of data we update the lower bound of
the neutralino mass to be about 18 GeV. From the second set of measurements we
derive that the excess around = 126 GeV, which however needs a
confirmation by further runs at the LHC, would imply a neutralino in the mass
range 18 GeV \lsim m_{\chi} \lsim 38 GeV, with neutralino--nucleon elastic
cross sections fitting well the results of the dark matter direct search
experiments DAMA/LIBRA and CRESST.Comment: 10 pages, 6 figures, typeset with ReVTeX4. v2:discussion on LHC Higgs
excess extended and one figure added. Matches version accepted for
publication on Phys.Rev.D. A version of the paper with full resolution
figures can be found at http://www.to.infn.it/~scopel/phenom_v2.pd
Extending the DAMA annual-modulation region by inclusion of the uncertainties in the astrophysical velocities
The original annual-modulation region, singled out by the DAMA/NaI experiment
for direct detection of WIMPs, is extended by taking into account the
uncertainties in the galactic astrophysical velocities. Also the effect due to
a possible bulk rotation for the dark matter halo is considered. We find that
the range for the WIMP mass becomes 30 GeV < m_chi < 130 GeV at 1-sigma C.L.
with a further extension in the upper bound, when a possible bulk rotation of
the dark matter halo is taken into account. We show that the DAMA results, when
interpreted in the framework of the Minimal Supersymmetric extension of the
Standard Model, are consistent with a relic neutralino as a dominant component
of cold dark matter (on the average in our universe and in our galactic halo).
It is also discussed the discovery potential for the relevant supersymmetric
configurations at accelerators of present generation.Comment: ReVTeX, 12 pages, 1 table, 7 figure
Does Solar Physics Provide Constraints to Weakly Interacting Massive Particles?
We investigate whether present data on helioseismology and solar neutrino
fluxes may constrain WIMP--matter interactions in the range of WIMP parameters
under current exploration in WIMP searches. We find that, for a WIMP mass of 30
GeV, once the effect of the presence of WIMPs in the Sun's interior is
maximized, the squared isothermal sound speed is modified, with respect to the
standard solar model, by at most 0.4% at the Sun's center. The maximal effect
on the Boron-8 solar neutrino flux is a reduction of 4.5%. Larger masses lead
to smaller effects. These results imply that present sensitivities in the
measurements of solar properties, though greatly improved in recent years, do
not provide information or constraints on WIMP properties of relevance for dark
matter. Furthermore, we show that, when current bounds from direct WIMP
searches are taken into account, the effect induced by WIMPs with dominant
coherent interactions are drastically reduced as compared to the values quoted
above. The case of neutralinos in the minimal supersymmetric standard model is
also discussed.Comment: 31 pages, 2 tables and 9 figures, typeset with ReVTeX4. The paper may
also be found at http://www.to.infn.it/~fornengo/papers/helio.ps.gz or
through http://www.to.infn.it/astropart/index.htm
Observations of annual modulation in direct detection of relic particles and light neutralinos
The long-standing model-independent annual modulation effect measured by the
DAMA Collaboration, which fulfills all the requirements of a dark matter annual
modulation signature, and the new result by the CoGeNT experiment that shows a
similar behavior are comparatively examined under the hypothesis of a dark
matter candidate particle interacting with the detectors' nuclei by a coherent
elastic process. The ensuing physical regions in the plane of the dark
matter-particle mass versus the dark matter-particle nucleon cross-section are
derived for various galactic halo models and by taking into account the impact
of various experimental uncertainties. It is shown that the DAMA and the CoGeNT
regions agree well between each other and are well fitted by a supersymmetric
model with light neutralinos which satisfies all available experimental
constraints, including the most recent results from CMS and ATLAS at the CERN
Large Hadron Collider.Comment: 13 pages, 7 figure
Further investigation of a relic neutralino as a possible origin of an annual-modulation effect in WIMP direct search
We analyze the annual-modulation effect, measured by the DAMA Collaboration
with the new implementation of a further two-years running, in the context of a
possible interpretation in terms of relic neutralinos. We impose over the set
of supersymmetric configurations, selected by the annual-modulation data, the
constraints derived from WIMP indirect measurements, and discuss the features
of the ensuing relic neutralinos. We critically discuss the sources of the main
theoretical uncertainties in the analysis of event rates for direct and
indirect WIMP searches.Comment: 29 pages, 12 figures, typeset with ReVTeX. In order to reduce size,
the version on the archive has low resolution figures. A full version of the
paper can be found at http://www.to.infn.it/~fornengo/papers
Quantitative Perspectives on Fifty Years of the Journal of the History of Biology
Journal of the History of Biology provides a fifty-year long record for
examining the evolution of the history of biology as a scholarly discipline. In
this paper, we present a new dataset and preliminary quantitative analysis of
the thematic content of JHB from the perspectives of geography, organisms, and
thematic fields. The geographic diversity of authors whose work appears in JHB
has increased steadily since 1968, but the geographic coverage of the content
of JHB articles remains strongly lopsided toward the United States, United
Kingdom, and western Europe and has diversified much less dramatically over
time. The taxonomic diversity of organisms discussed in JHB increased steadily
between 1968 and the late 1990s but declined in later years, mirroring broader
patterns of diversification previously reported in the biomedical research
literature. Finally, we used a combination of topic modeling and nonlinear
dimensionality reduction techniques to develop a model of multi-article fields
within JHB. We found evidence for directional changes in the representation of
fields on multiple scales. The diversity of JHB with regard to the
representation of thematic fields has increased overall, with most of that
diversification occurring in recent years. Drawing on the dataset generated in
the course of this analysis, as well as web services in the emerging digital
history and philosophy of science ecosystem, we have developed an interactive
web platform for exploring the content of JHB, and we provide a brief overview
of the platform in this article. As a whole, the data and analyses presented
here provide a starting-place for further critical reflection on the evolution
of the history of biology over the past half-century.Comment: 45 pages, 14 figures, 4 table
Supersymmetric Dark Matter and the Reheating Temperature of the Universe
Since the thermal history of the Universe is unknown before the epoch of
primordial nucleosynthesis, the largest temperature of the radiation dominated
phase (the reheating temperature) might have been as low as 1 MeV. We perform a
quantitative study of supersymmetric dark matter relic abundance in
cosmological scenarios with low reheating temperature. We show that, for values
of the reheating temperature smaller than about 30 GeV, the domains of the
supergravity parameter space which are compatible with the hypothesis that dark
matter is composed by neutralinos are largely enhanced. We also find a lower
bound on the reheating temperature: if the latter is smaller than about 1 GeV
neutralinos cannot be efficiently produced in the early Universe and then they
are not able to explain the present amount of dark matter.Comment: 21 pages, 5 figures, typeset with ReVTeX4. The paper may also be
found at http://www.to.infn.it/~fornengo/papers/reheating.ps.g
Neutralino properties in the light of a further indication of an annual modulation effect in WIMP direct search
We demonstrate that the further indication of a possible annual modulation
effect, singled out by the DAMA/NaI experiment for WIMP direct detection, is
widely compatible with an interpretation in terms of a relic neutralino as the
major component of dark matter in the Universe. We discuss the supersymmetric
features of this neutralino in the Minimal Supersymmetric extension of the
Standard Model (MSSM) and their implications for searches at accelerators.Comment: 15 pages, ReVTeX, 9 figures (included as PS files
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