869 research outputs found
Candidates for non-baryonic dark matter
This report is a brief review of the efforts to explain the nature of
non-baryonic dark matter and of the studies devoted to the search for relic
particles. Among the different dark matter candidates, special attention is
devoted to relic neutralinos, by giving an overview of the recent calculations
of its relic abundance and detection rates in a wide variety of supersymmetric
schemes.Comment: 13 pages, 10 figures, typeset with ReVTeX, uses espcrc2.sty. Invited
review talk presented at "Topics in Astroparticle and Underground Physics
(TAUP 2001)" Laboratori Nazionali del Gran Sasso, Italy, September 8-12,
2001. References added. The paper may also be downloaded from
http://www.to.infn.it/~fornengo/proceedings/taup01.ps.g
Particle dark matter searches in the anisotropic sky
Anisotropies in the electromagnetic emission produced by dark matter
annihilation or decay in the extragalactic sky are a recent tool in the quest
for a particle dark matter evidence. We review the formalism to compute the
two-point angular power spectrum in the halo-model approach and discuss the
features and the relative size of the various auto- and cross-correlation
signals that can be envisaged for anisotropy studies. From the side of particle
dark matter signals, we consider the full multi-wavelength spectrum, from the
radio emission to X-ray and gamma-ray productions. We discuss the angular power
spectra of the auto-correlation of each of these signals and of the
cross-correlation between any pair of them. We then extend the search to
comprise specific gravitational tracers of dark matter distribution in the
Universe: weak-lensing cosmic shear, large-scale-structure matter distribution
and CMB-lensing. We have shown that cross-correlating a multi-wavelength dark
matter signal (which is a direct manifestation of its particle physics nature)
with a gravitational tracer (which is a manifestation of the presence of large
amounts of unseen matter in the Universe) may offer a promising tool to
demonstrate that what we call dark matter is indeed formed by elementary
particles.Comment: 16 pages, 11 figures. Prepared as inaugural article for Frontiers in
High-Energy and Astroparticle Physics. v2: few comments added, to appear in
Frontiers (Hypothesis and Theory Article
Cold Dark Matter and Neutralinos
Neutralinos are natural candidates for cold dark matter in many realizations
of supersymmetry. We briefly review our recent results in the evaluation of
neutralino relic abundance and direct detection rates in a class of
supergravity models.Comment: 4 pages, 4 figures, uses espcrc2.sty. Proc. of "Sources and detection
of dark matter and dark energy in the Universe (DM2002)". The version on the
archive has low-resolution figures. The paper with high-resolution figures
can be found at
http://www.to.infn.it/~fornengo/proceedings/marinadelrey02.ps.gz or through
http://www.to.infn.it/astropart
Gravitational Effects on the Neutrino Oscillation
The propagation of neutrinos in a gravitational field is studied. A method of
calculating a covariant quantum-mechanical phase in a curved space-time is
presented. The result is used to calculate gravitational effects on the
neutrino oscillation in the presence of a gravitational field. We restrict our
discussion to the case of the Schwartzschild metric. Specifically, the cases of
the radial propagation and the non-radial propagation are considered. A
possible application to gravitational lensing of neutrinos is also suggested.Comment: 15 pages, RevTex, No figures. Minor modifications and some typos
correcte
A consistent model for leptogenesis, dark matter and the IceCube signal
We discuss a left-right symmetric extension of the Standard Model in which
the three additional right-handed neutrinos play a central role in explaining
the baryon asymmetry of the Universe, the dark matter abundance and the ultra
energetic signal detected by the IceCube experiment. The energy spectrum and
neutrino flux measured by IceCube are ascribed to the decays of the lightest
right-handed neutrino , thus fixing its mass and lifetime, while the
production of in the primordial thermal bath occurs via a freeze-in
mechanism driven by the additional interactions. The constraints
imposed by IceCube and the dark matter abundance allow nonetheless the heavier
right-handed neutrinos to realize a standard type-I seesaw leptogenesis, with
the asymmetry dominantly produced by the next-to-lightest neutrino .
Further consequences and predictions of the model are that: the
production implies a specific power-law relation between the reheating
temperature of the Universe and the vacuum expectation value of the
triplet; leptogenesis imposes a lower bound on the reheating temperature of the
Universe at 7\times10^9\,\mbox{GeV}. Additionally, the model requires a
vanishing absolute neutrino mass scale .Comment: 19 pages, 4 figures. Constraints from cosmic-ray antiprotons and
gamma rays added, with hadrophobic assignment of the matter multiplets to
satisfy bounds. References added. Matches version published in JHE
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