Francesca Rosati

Although a direct interaction between WIMP CDM candidates and scalar Quintessence fields (sources of Dark Energy) poses severe phenomenological threats, yet it is possible that the presence of Quintessence produces profound deviations in the expansion rate of the early Universe at the moment of WIMP decoupling, hence causing significant enhancement...

A general model for the cosmological evolution of the fine structure constant \alpha driven by a typical Quintessence scenario is presented. We consider a coupling between the Quintessence scalar \phi and the electromagnetic kinetic term F^2, given by a general function B_F(\phi). We study the dependence of the cosmological \Delta\alpha(t) upon the...

Two mechanisms by which the Quintessence scalar could enhance the relic abundance of dark matter particles are discussed. This effect can have an impact on supersymmetric candidates for dark matter. Comment: 6 pages; to appear in the Proceedings of "Phi in the Sky - the quest for cosmological scalar fields", 8-10 July 2004, Porto (PT)

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...

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...

Results of a recent study on how the Quintessence scalar could affect the relic abundance of dark matter particles are presented.

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 Q...

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.

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 stabilisatio...

The issue of Supersymmetry breaking in the context of Supergravity models of Quintessence is discussed. Comment: 4 pages, Proceedings of Euresco conference 'Frontiers in Particle Astrophysics and Cosmology', San Feliu de Guixols, Spain, 30 Sept - 5 Oct 2000

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 the...

The most recent cosmological data point in the direction of a cosmological constant dominated universe. A suitable candidate for providing the required acceleration is a rolling scalar field named ``quintessence''. We address the issue of building a particle physics model for quintessence in the context of Susy QCD. We then go on to ask if the quin...

Recent data point in the direction of a cosmological constant dominated universe. We investigate the role of supersymmetric QCD with Nf<Nc as a possible candidate for a dynamical cosmological constant (“quintessence”). When Nf>1, the multiscalar dynamics is fully taken into account, showing that a certain degree of flavor symmetry in the initial co...

Recent data point in the direction of a $\Lambda$ dominated universe. We briefly review ``Quintessence'' as a model for a dynamical cosmological term and analyse the role of Susy QCD as a possible particle physics candidate. The multiscalar content of the theory is fully taken into account and interaction with other cosmological fields is discussed...

Attention has been recently drawn towards models in which inflation and quintessence schemes are unified. In such `quintessential inflation' models, a unique scalar field is required to play both the role of the inflaton and of the late-time dynamical cosmological constant. We address the issue of the initial conditions for quintessence in this con...

Recent data point in the direction of a cosmological constant dominated universe. We investigate the role of supersymmetric QCD with N_f < N_c as a possible candidate for dynamical cosmological constant (``quintessence''). We take in full consideration the multi-scalar nature of the model, allowing for different initial conditions for the N_f indep...

Last year observations had a profound impact on our views on the amount and nature of dark matter in the universe. We give a brief review of the recent history of dark matter models beyond the pure cold dark matter universe. In view of the most recent cosmological data, we then go on to discuss models with a positive cosmological constant. Finally...