2 00 5 On the smallness of the cosmological constant in SUGRA models

ar X iv : h ep - p h / 05 11 25 9 v 1 2 2 N ov 2 00 5 On the smallness of the cosmological constant in SUGRA models

In no–scale supergravity global symmetries protect local supersymmetry and a zero value for the cosmological constant. We consider the breakdown of these symmetries and present a minimal SUGRA model motivated by the multiple point principle, in which the total vacuum energy density is naturally tiny. In order to reproduce the observed value of the cosmological constant and preserve gauge coupli...

On the Smallness of the Cosmological Constant in SUGRA Models Inspired by Degenerate Vacua

In the no–scale supergravity global symmetries protect local supersymmetry and a zero value for the cosmological constant. The breakdown of these symmetries, which ensures the vanishing of the vacuum energy density, results in a set of degenerate vacua with broken and unbroken supersymmetry leading to the natural realisation of the multiple point principle (MPP). In the MPP inspired SUGRA model...

On the smallness of the cosmological constant in SUGRA models with Planck scale SUSY breaking and degenerate vacua

Cosmological Constant in SUGRA Models Inspired by Degenerate Vacua

Present astrophysical and cosmological observations indicate that there is a tiny energy density (the cosmological constant) Λ ∼ 10M Pl ∼ 10 M Z spread all over the Universe, which is responsible for its accelerated expansion. This energy density is incredibly small as compared with the contribution of QCD condensates to the total vacuum energy density, which is expected to be of order ΛQCD ≃ 1...

ar X iv : a st ro - p h / 06 07 26 2 v 1 1 2 Ju l 2 00 6 Constraints on Quintessence Using Recent Cosmological Data

Recent data, including the three–year WMAP data, the full 2dF galaxy power spectrum and the first–year data of the Supernova Legacy Survey, are used to constrain model parameters in quintessence cosmologies. In particular, we discuss the inverse power–law (RP) and SUGRA potentials and compare parameter constraints with those for ΛCDM. Both potentials fit current observations with a goodness of ...