arXiv subjects

F. Rosati

Publications and source records attributed to F. Rosati.

7 recordsLinked to original sources

arXiv2004

Dark Matter Relic Abundance and Scalar-Tensor Dark Energy

Scalar-tensor theories of gravity provide a consistent framework to accommodate an ultra-light quintessence scalar field. While the equivalence principle is respected by construction, deviations from General Relativity and standard cosmology may show up at nucleosynthesis, CMB, and solar system tests of gravity. After imposing all the bounds coming from these observations, we consider the expansion rate of the universe at WIMP decoupling, showing that it can lead to an enhancement of the dark matter relic density up to few orders of magnitude with respect to the standard case. This effect can have an impact on supersymmetric candidates for dark matter.

astro-ph↗

arXiv2004

Enhancement of Dark Matter Abundance in Scalar-Tensor Dark Energy

In Scalar-Tensor theories of gravity, the expansion rate of the universe in the past may differ considerably from the standard one. After imposing the constraints coming from nucleosynthesis, CMB, type Ia supernovae, and solar system tests of General Relativity, we consider the expansion rate of the universe at WIMP decoupling, showing that it can lead to an enhancement of the dark matter relic density of some orders of magnitude with respect to the standard case. This effect may have a deep impact on most popular candidates for dark matter, as the supersymmetric neutralino.

astro-ph↗

arXiv2003

Quintessential Enhancement of Dark Matter Abundance

The presence of a dynamical scalar field in the early universe could significantly affect the `freeze-out' time of particle species. In particular, it was recently shown that an enhancement of the relic abundance of neutralinos can be produced in this way. We examine under which conditions this primordial scalar field could be identified with the Quintessence scalar and find, through concrete examples, that modifications to the standard paradigm are necessary. We discuss two possible cases: the presence of more scalars and the switching on of an interaction.

hep-ph↗

arXiv2002

Scalar fields and cosmological attractor solutions

Results of a general study on the dynamics of cosmological scalar fields with arbitrary potentials are presented. Exact and approximate attractor solutions are found, with applications to quintessence, moduli stabilization and inflation.

astro-ph↗

arXiv2001

Applications of scalar attractor solutions to Cosmology

We develop a framework to study the phase space of a system consisting of a scalar field rolling down an arbitrary potential with varying slope and a background fluid, in a cosmological setting. We give analytical approximate solutions of the field evolution and discuss applications of its features to the issues of quintessence, moduli stabilisation and quintessential inflation.

astro-ph↗

arXiv2001

Renormalization Group Approach to Spin Glass Systems

A renormalization group transformation suitable for spin glass models and, more generally, for disordered models, is presented. The procedure is non-standard in both the nature of the additional interactions and the coarse graining transformation, that is performed on the overlap probability measure (which is clearly non-Gibbsian). Universality classes are thus naturally defined on a large set of models, going from $\Z_2$ and Gaussian spin glasses to Ising and fully frustrated models, and others.

cond-mat.dis-nn↗

arXiv2000

Quintessence models in Supergravity

Scalar field models of quintessence typically require that the expectation value of the field today is of order the Planck mass, if we want them to explain the observed acceleration of the Universe. This suggests that we should be considering models in the context of supergravity. We discuss a particular class of supergravity models and analyze their behavior under different choices of the Kahler metric.

hep-ph↗