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 $N_1$, thus fixing its mass and lifetime, while the production of $N_1$ in the primordial thermal bath occurs via a freeze-in mechanism driven by the additional $SU(2)_R$ 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 $B-L$ asymmetry dominantly produced by the next-to-lightest neutrino $N_2$. Further consequences and predictions of the model are that: the $N_1$ production implies a specific power-law relation between the reheating temperature of the Universe and the vacuum expectation value of the $SU(2)_R$ 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 $m_1\simeq0$.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