444 research outputs found
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
Embedding the 125 GeV Higgs boson measured at the LHC in an effective MSSM: possible implications for neutralino dark matter
We analyze the phenomenological consequences of assuming that the 125 GeV
boson measured at the LHC coincides with one of the two CP-even Higgs bosons of
an effective Minimal Supersymmetric extension of the Standard Model at the
electroweak scale. We consider the two ensuing scenarios and discuss critically
the role of the various experimental data (mainly obtained at colliders and at
B-factories) which provide actual or potential constraints to supersymmetric
properties. Within these scenarios, properties of neutralinos as dark matter
particles are analyzed from the point of view of their cosmological abundance
and rates for direct and indirect detections.Comment: 14 pages, 14 figures, typeset with ReVTeX4. A version of the paper
with full resolution figures can be found at
http://www.to.infn.it/~scopel/embedding.pd
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
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