603 research outputs found
Direct detection of neutralino dark mattter in non-standard cosmologies
We compute the neutralino direct detection rate in non-standard cosmological
scenarios where neutralinos account for the dark matter of the Universe.
Significant differences are found when such rates are compared with those
predicted by the standard cosmological model. For bino-like neutralinos, the
main feature is the presence of additional light (m_\chi\lesssim 40\gev) and
heavy (m_\chi\gtrsim 600\gev) neutralinos with detection rates within the
sensitivity of future dark matter experiments. For higgsino- and wino-like
neutralinos lighter than m_\chi \sim 1\tev, enhancements of more than two
orders of magnitude in the largest detection rates are observed. Thus, if dark
matter is made up of neutralinos, the prospects for their direct detection are
in general more promising than in the standard cosmology.Comment: 10 pages, 5 figure
Measuring the prompt atmospheric neutrino flux with down-going muons in neutrino telescopes
In the TeV energy region and above, the uncertainty in the level of prompt
atmospheric neutrinos would limit the search for diffuse astrophysical
neutrinos. We suggest that neutrino telescopes may provide an empirical
determination of the flux of prompt atmospheric electron and muon neutrinos by
measuring the flux of prompt down-going muons. Our suggestion is based on the
consideration that prompt neutrino and prompt muon fluxes at sea level are
almost identical.Comment: 4 pages, 3 figure
Super-Kamiokande 0.07 eV Neutrinos in Cosmology: Hot Dark Matter and the Highest Energy Cosmic Rays
Relic neutrinos with mass in the range indicated by Super-Kamiokande results
if neutrino masses are hierarchial (about 0.07 eV) are many times deemed too
light to be cosmologically relevant. Here we remark that these neutrinos may
significantly contribute to the dark matter of the Universe (with a large
lepton asymmetry ) and that their existence might be revealed by the
spectrum of ultra high energy cosmic rays (maybe even in the absence of a large
).Comment: Talk given at the ``4th International Symposium on Sources and
Detection of Dark Matter in the Universe", February 23-25, 2000, Marina del
Rey, CA (to appear in its proceedings) and at the ``Cosmic Genesis and
Fundamental Physics" workshop, October 28-30, 1999, Sonoma State University,
Santa Rosa, CA. (8 p. 1 fig.
DAMA detection claim is still compatible with all other DM searches
We show that the annual modulation signal observed by DAMA can be reconciled
with all other negative results from dark matter searches with a conventional
halo model for particle masses around 5 to 9 GeV. We also show which particular
dark matter stream could produce the DAMA signal.Comment: Talk given at TAUP2005, Sept. 10-14 2005, Zaragoza (Spain). 3 pages,
4 figure
GZK photons as UHECR above 10 eV
"GZK photons" are produced by extragalactic nucleons through the resonant
photoproduction of pions. We present the expected range of the GZK photon
fraction of UHECR, assuming a particular UHECR spectrum and primary nucleons,
and compare it with the minimal photon fraction predicted by Top-Down models.Comment: Talk given at TAUP2005, Sept. 10-14 2005, Zaragoza (Spain); 3 pages,
2 figure
Saturation Physics in Ultra High Energy Cosmic Rays: Heavy Quark Production
In this work we estimate the heavy quark production in the interaction of
ultra high energy cosmic rays in the atmosphere, considering that the primary
cosmic ray is a proton or a photon. At these energies the saturation momentum
Q_{sat}^2 stays above the hard scale \mu_c^2=4m_c^2, implying charm production
probing the saturation regime. In particular, we show that the ep HERA data
presents a scaling on \tau_c = (Q^2+\mu_c^2)/Q_{sat}^2. We derive our results
considering the dipole picture and the Color Glass Condensate formalism, which
one shows to be able to describe the heavy quark production in photon-proton
and proton-proton collisions. Nuclear effects are considered in computation of
cross sections for scattering on air nuclei. Implications on the flux of prompt
leptons at the earth are analyzed and a large suppression is predicted.Comment: 18 pages, 10 figures, 2 tables. Version to be published in JHE
Decay of the Z Boson into Scalar Particles
In extensions of the standard model, light scalar particles are often
possible because of symmetry considerations. We study the decay of the Z boson
into such particles. In particular, we consider for illustration the scalar
sector of a recently proposed model of the 17-keV neutrino which satisfies all
laboratory, astrophysical, and cosmological constraints.Comment: 11 pages (2 figures, not included) (Revised, Oct 1992). Some
equations have been corrected and 1 figure has been eliminate
Anomaly mediated SUSY breaking scenarios in the light of cosmology and in the dark (matter)
Anomaly mediation is a popular and well motivated supersymmetry breaking
scenario. Different possible detailed realisations of this set-up are studied
and actively searched for at colliders. Apart from limits coming from flavour,
low energy physics and direct collider searches, these models are usually
constrained by the requirement of reproducing the observations on dark matter
density in the universe. We reanalyse these bounds and in particular we focus
on the dark matter bounds both considering the standard cosmological model and
alternative cosmological scenarios. These scenarios do not change the
observable cosmology but relic dark matter density bounds strongly depend on
them. We consider few benchmark points excluded by standard cosmology dark
matter bounds and suggest that loosening the dark matter constraints is
necessary in order to avoid a too strong (cosmological) model dependence in the
limits that are obtained for these models. We also discuss briefly the
implications for phenomenology and in particular at the Large Hadron Collider.Comment: 37 pages, 20 figures, 1 tabl
Prompt atmospheric neutrinos and muons: dependence on the gluon distribution function
We compute the next-to-leading order QCD predictions for the vertical flux of
atmospheric muons and neutrinos from decays of charmed particles, for different
PDF's (MRS-R1, MRS-R2, CTEQ-4M and MRST) and different extrapolations of these
at small partonic momentum fraction x. We find that the predicted fluxes vary
up to almost two orders of magnitude at the largest energies studied, depending
on the chosen extrapolation of the PDF's. We show that the spectral index of
the atmospheric leptonic fluxes depends linearly on the slope of the gluon
distribution function at very small x. This suggests the possibility of
obtaining some bounds on this slope in ``neutrino telescopes'', at values of x
not reachable at colliders, provided the spectral index of atmospheric leptonic
fluxes could be determined.Comment: 20 pages including 8 figure
Particle-Antiparticle Asymmetry Due to Non-Renormalizable Effective Interactions
We consider a model for generating a particle-antiparticle asymmetry through
out-of-equilibrium decays of a massive particle due to non-renormalizable,
effective interactions.Comment: preliminary version, 38 pages; LaTeX source, epsf.sty and EPS files
included in tar archiv
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