5,617 research outputs found
Ultra High Energy Neutrino-Relic Neutrino Interactions In Dark Halos to Solve Infrared-Tev And GZK Cut-Off
Ultra High Energy Neutrino scattering on Relic Light Neutrinos in Dark
Galactic or Local Group lead to Z and WW,ZZ showering: the nucleon component of
the shower may overcome the GZK cut-off while the electro-magnetic tail at TeVs
up to EeVs energy may solve the Infrared-TeV cut-off in a natural way.
Different Gamma TeV puzzles may find a solution within this scenario: new
predictions on UHECR spectra in future data are derived.Comment: 4 pages, 3 figures, 2 tables ICRC 2001 HE 3.6 Dark Matter - German
Why Tau First?
Electron neutrino has been the first neutral lepton to be foreseen and
discovered last century. The un-ordered muon and its neutrino arose later by
cosmic rays. The tau discover, the heaviest, the most unstable charged lepton,
was found surprisingly on 1975. Its neutrino was hardly revealed just on 2000.
So why High Energy Neutrino Astronomy should rise first via tau neutrino, the
last, the most rare one? The reasons are based on a chain of three favorable
coincidences found last decade: the neutrino masses and their flavor mixing,
the UHECR opacity on Cosmic Black Body (GZK cut off on BBR), the amplified tau
air-shower decaying in flight. Indeed guaranteed UHE GZK tau neutrinos, feed by
muon mixing, while skimming the Earth might lead to boosted UHE tau, mostly
horizontal ones. These UHE lepton decay in flight are spread, amplified, noise
free Air-Shower: a huge event for an unique particle. To be observed soon:
within Auger sky, in present decade. Its discover may sign of the first tau
appearance.Comment: 8 pages, 4 figure
Upward Tau Air Showers from Earth
We estimate the rate of observable Horizontal and Upward Tau Air-Showers
(HORTAUs, UPTAUS) considering both the Earth opacity and the finite size of the
terrestrial atmosphere. We calculate the effective target volumes and masses
for Tau air-showers emerging from the Earth. The resulting model-independent
masses for satellite experiments such as EUSO may encompass at E_nu_tau = 10^19
eV a very large volume, V= 1020 km^3. Adopting simple power law neutrino
fluxes, E^-2 and E^-1, calibrated to GZK-like and Z-Burst-like models, we
estimate that at E= 10^19 eV nearly half a dozen horizontal shower events
should be detected by EUSO in three years of data collection by the
"guaranteed" GZK neutrino flux. We also find that the equivalent mass for an
Earth outer layer made of rock is dominant compared to the water, contrary to
simplified all-rock/all-water Earth models and previous Montecarlo simulations.
Therefore we expect an enhancement of neutrino detection along continental
shelves nearby the highest mountain chains, also given the better geometrical
acceptance for Earth skimming neutrinos. The Auger experiment might reveal such
a signature at E_nu= 10^{18} eV (with 26 events in 3 yr) towards the Andes, if
the angular resolution at the horizon (both in azimuth and zenith) would reach
an accuracy of nearly one degree needed to disentangle tau air showers from
common UHECR. The number of events increases at lower energies; therefore we
suggest an extension of the EUSO and Auger sensitivity down to (or even below)
E_nu = 10^19 eV and E_nu = 10^18 eV respectively.Comment: New version resubmitted to ApJ on the 6th April 2004; 55 Pages,20
figures, major changes following referee reques
Preliminary results of a Mesoscale Model for MARS
The Earth atmospheric circulation has been studied for long time using both GCM (General Circulation Models) and Mesoscale Models or LAM (Limited Area Models). The latter have been widely applied to study local circulation at high resolution and for weather forecasting. In the last years, the Martian atmosphere arouse the interest of the scientific community, both for supporting the landing of Beagle 2 lander and for studying and assessing similarities/differences with the Earth atmosphere. To this aim, GCM have been successfully used. Recently, also Earth LAMs have been changed to simulate the Mars atmosphere, showing good results. The scarce availability of observations did not allowed for validating these models. In this work an attempt is made to validate the newly developed MARS-MM5 against GCM. The model simulation produced using a data base on the basis of output from multi-annual integration of two CGM (see Lewis S. R. et al., J. Geophys. Res., 104 (E10) (1999) 177) is used for statistically evaluates MARS-MM5. The preliminary results suggest that MARS-MM5 is able to correctly reproduce the Mars atmosphere, indeed either the horizontal and the vertical structure of temperature produced by MARS-MM5 is in good agreement with the ones produced by GCM. A few discrepancies are found in the PBL, probably produced by a different parameterization
Directional depletion interactions in shaped particles
Entropic forces in colloidal suspensions and in polymer-colloid systems are
of long-standing and continuing interest. Experiments show how entropic forces
can be used to control the self-assembly of colloidal particles. Significant
advances in colloidal synthesis made in the past two decades have enabled the
preparation of high quality nano-particles with well-controlled sizes, shapes,
and compositions, indicating that such particles can be utilized as "artificial
atoms" to build new materials. To elucidate the effects of the shape of
particles upon the magnitude of entropic interaction, we analyse the entropic
interactions of two cut-spheres. We show that the solvent induces a strong
directional depletion attraction among flat faces of the cut-spheres. Such an
effect highlights the possibility of using the shape of particles to control
directionality and strength of interaction.Comment: 6 pages, 4 figure
Shadows of Relic Neutrino Masses and Spectra on Highest Energy GZK Cosmic Rays
The Ultra High Energy (UHE) neutrino scattering onto relic cosmic neutrinos
in galactic and local halos offers an unique way to overcome GZK cut-off. The
UHE nu secondary of UHE photo-pion decays may escape the GZK cut-off and travel
on cosmic distances hitting local light relic neutrinos clustered in dark
halos. The Z resonant production and the competitive W^+W^-, ZZ pair production
define a characteristic imprint on hadronic consequent UHECR spectra. This
imprint keeps memory both of the primary UHE nu spectra as well as of the
possible relic neutrino masses values, energy spectra and relic densities. Such
an hadronic showering imprint should reflect into spectra morphology of cosmic
rays near and above GZK 10^{19}-10^{21}eV cut-off energies. A possible neutrino
degenerate masses at eVs or a more complex and significant neutrino mass split
below or near Super-Kamiokande \triangle m_{\nu_{SK}}= 0.1 eV masses might be
reflected after each corresponding Z peak showering, into new twin unexpected
UHECR flux modulation behind GZK energies: E_{p} sim 3(frac{triangle
m_{\nu_{SK}}}/m_{\nu}10^{21}),eV.
Other shadowsof lightest, nearly massless, neutrinos m_{nu_{2K} simeq 0.001eV
simeq kT_{\nu}, their lowest relic temperatures, energies and densities might
be also reflected at even higher energies edges near Grand Unification: E_{p}
\sim 2.2(m_{\nu_{2K}/E_{\nu}})10^{23}, eV .Comment: 14 pages, 6 Figures,Invited Talk Heidelberg DARK 200
Comparison Among Two Liquid Formulations of L-thyroxine in the Treatment of Congenital Hypothyroidism in the First Month of Life: A Pilot Study
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