397 research outputs found
Axionic shortcuts for high energy photons
We study the photon axion mixing in the presence of large extra dimensions.
The eigenvalues and eigenstates of the mixing matrix are analyzed and we
establish the resonance condition for the total conversion of a high energy
photon into a Kaluza-Klein (KK) axion state. This resonant transition, a photon
transformed into a KK axion travelling freely through the bulk and converting
back into a photon, may provide a plausible explanation for the transparency of
the universe to energetic photons. If the brane we live in is curved, then
there are shortcuts through the bulk, which the axion can take. Within our
model, the photons having the appropriate resonance energy are using the
axionic shortcut and arrive earlier compared to the photons which follow the
geodesic on the brane. We suggest that such axionic shortcuts are at the root
of the dispersion of time arrival of photons observed by the MAGIC telescope.
We indicate also the cosmological significance of the existence of axionic
shortcuts for the photon.Comment: 7 page
Single event effects in static and dynamic registers in a CMOS technology
We have studied single event effects in static and dynamic registers designed in a quarter micron CMOS process. In our design, we systematically used guardrings and enclosed (edgeless) transistor geometry to improve the total dose tolerance. This design technique improved both the SEL and SEU sensitivity of the circuits. Using SPICE simulations, the measured smooth transition of the cross-section curve between LET threshold and saturation has been traced to the presence of four different upset modes, each corresponding to a different critical charge and sensitive area. A new architecture to protect the content of storage cells has been developed, and a threshold LET around 89 MeV cm/sup 2/ mg/sup -1/ has been measured for this cell at a power supply voltage of 2 V
New Physics Potential with a Neutrino Telescope
Active Galactic Nuclei are considered as sources of neutrinos, with neutrino
energies extending up to 10^{18} eV. It is expected that these highly energetic
cosmic neutrinos will be detected by the neutrino telescopes, presently under
construction. The detection process is very sensitive to the total muon
neutrino cross-section. We examine how the total cross section changes at high
energies, by the single production of excited fermions (excited muon and
muon-neutrino). For parameters (masses, couplings) of the excited fermions
allowed by the experimental constraints, we find that for energies of the
incoming muon-neutrino above 100 TeV the cross-section for single production of
(excited muon and muon-neutrino) supersedes the standard total cross-section.Comment: 12 pages and 2 figures; typset using revtex; postscript files for the
figures provide
Cosmic Rays and Large Extra Dimensions
We have proposed that the cosmic ray spectrum "knee", the steepening of the
cosmic ray spectrum at energy E \gsim 10^{15.5} eV, is due to "new physics",
namely new interactions at TeV cm energies which produce particles undetected
by the experimental apparatus. In this letter we examine specifically the
possibility that this interaction is low scale gravity. We consider that the
graviton propagates, besides the usual four dimensions, into an additional
, compactified, large dimensions and we estimate the graviton
production in collisions in the high energy approximation where graviton
emission is factorized. We find that the cross section for graviton production
rises as fast as , where is the fundamental
scale of gravity in dimensions, and that the distribution of
radiating a fraction of the initial particle's energy into gravitational
energy (which goes undetected) behaves as . The missing
energy leads to an underestimate of the true energy and generates a break in
the {\sl inferred} cosmic ray spectrum (the "kne"). By fitting the cosmic ray
spectrum data we deduce that the favorite values for the parameters of the
theory are TeV and .Comment: 8 pages, 1 figur
Neutrino tomography - Learning about the Earth's interior using the propagation of neutrinos
Because the propagation of neutrinos is affected by the presence of Earth
matter, it opens new possibilities to probe the Earth's interior. Different
approaches range from techniques based upon the interaction of high energy
(above TeV) neutrinos with Earth matter, to methods using the MSW effect on the
neutrino oscillations of low energy (MeV to GeV) neutrinos. In principle,
neutrinos from many different sources (sun, atmosphere, supernovae, beams etc.)
can be used. In this talk, we summarize and compare different approaches with
an emphasis on more recent developments. In addition, we point out other
geophysical aspects relevant for neutrino oscillations.Comment: 22 pages, 9 figures. Proceedings of ``Neutrino sciences 2005:
Neutrino geophysics'', December 14-16, 2005, Honolulu, USA. Minor changes,
some references added. Final version to appear in Earth, Moon, and Planet
A Random Matrix Approach to Language Acquisition
Since language is tied to cognition, we expect the linguistic structures to
reflect patterns we encounter in nature and analyzed by physics. Within this
realm we investigate the process of protolanguage acquisition, using analytical
and tractable methods developed within physics. A protolanguage is a mapping
between sounds and objects (or concepts) of the perceived world. This mapping
is represented by a matrix and the linguistic interaction among individuals is
described by a random matrix model. There are two essential parameters in our
approach. The strength of the linguistic interaction , which following
Chomsky's tradition, we consider as a genetically determined ability, and the
number of employed sounds (the lexicon size). Our model of linguistic
interaction is analytically studied using methods of statistical physics and
simulated by Monte Carlo techniques. The analysis reveals an intricate
relationship between the innate propensity for language acquisition and
the lexicon size , . Thus a small increase of the
genetically determined may lead to an incredible lexical explosion. Our
approximate scheme offers an explanation for the biological affinity of
different species and their simultaneous linguistic disparity.Comment: 16 pages, 4 figures. Submitted to JSTA
Lifetime Economic Burden of Intimate Partner Violence Among U.S. Adults
Introduction: This study estimated the U.S. lifetime per-victim cost and economic burden of intimate partner violence.
Methods: Data from previous studies were combined with 2012 U.S. National Intimate Partner and Sexual Violence Survey data in a mathematical model. Intimate partner violence was defined as contact sexual violence, physical violence, or stalking victimization with related impact (e.g., missed work days). Costs included attributable impaired health, lost productivity, and criminal justice costs from the societal perspective. Mean age at first victimization was assessed as 25 years. Future costs were discounted by 3%. The main outcome measures were the mean per-victim (female and male) and total population (or economic burden) lifetime cost of intimate partner violence. Secondary outcome measures were marginal outcome probabilities among victims (e.g., anxiety disorder) and associated costs. Analysis was conducted in 2017.
Results: The estimated intimate partner violence lifetime cost was 23,414 per male victim, or a population economic burden of nearly ) over victims’ lifetimes, based on 43 million U.S. adults with victimization history. This estimate included 1.3 trillion (37%) in lost productivity among victims and perpetrators, 62 billion (2%) in other costs, including victim property loss or damage. Government sources pay an estimated $1.3 trillion (37%) of the lifetime economic burden.
Conclusions: Preventing intimate partner violence is possible and could avoid substantial costs. These findings can inform the potential benefit of prioritizing prevention, as well as evaluation of implemented prevention strategies
Geotomography with solar and supernova neutrinos
We show how by studying the Earth matter effect on oscillations of solar and
supernova neutrinos inside the Earth one can in principle reconstruct the
electron number density profile of the Earth. A direct inversion of the
oscillation problem is possible due to the existence of a very simple analytic
formula for the Earth matter effect on oscillations of solar and supernova
neutrinos. From the point of view of the Earth tomography, these oscillations
have a number of advantages over the oscillations of the accelerator or
atmospheric neutrinos, which stem from the fact that solar and supernova
neutrinos are coming to the Earth as mass eigenstates rather than flavour
eigenstates. In particular, this allows reconstruction of density profiles even
over relatively short neutrino path lengths in the Earth, and also of
asymmetric profiles. We study the requirements that future experiments must
meet to achieve a given accuracy of the tomography of the Earth.Comment: 35 pages, 7 figures; minor textual changes in section
Fermionic dispersion relations at finite temperature and non-vanishing chemical potentials in the minimal standard model
We calculate the fermionic dispersion relations in the minimal standard model
at finite temperature in presence of non-vanishing chemical potentials due to
the CP-asymmetric fermionic background. The dispersion relations are calculated
for a vacuum expectation value of the Higgs field equal to zero (unbroken
electroweak symmetry). The calculation is performed in the real time formalism
of the thermal field theory at one-loop order in a general gauge. The
fermionic self-energy is calculated at leading order in temperature and
chemical potential and this fact permits us to obtain gauge invariant
analytical expressions for the dispersion relations.Comment: LaTeX File, 18 pages, 1 Postscript figur
Enhanced solar anti-neutrino flux in random magnetic fields
We discuss the impact of the recent KamLAND constraint on the solar
anti-neutrino flux on the analysis of solar neutrino data in the presence of
Majorana neutrino transition magnetic moments and solar magnetic fields. We
consider different stationary solar magnetic field models, both regular and
random, highlighting the strong enhancement in the anti-neutrino production
rates that characterize turbulent solar magnetic field models. Moreover, we
show that for such magnetic fields inside the Sun, one can constrain the
intrinsic neutrino magnetic moment down to the level of mu_nu lessthan few
times 10^-12 x mu_B irrespective of details of the underlying turbulence model.
This limit is more stringent than all current experimental sensitivities, and
similar to the most stringent bounds obtained from stellar cooling. We also
comment on the robustness of this limit and show that at most it might be
weakened by one order of magnitude, under very unlikely circumstances.Comment: 25 pages, 5 figures; final version to appear in Phys. Rev.
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