4 research outputs found
Quintessence Restrictions on Negative Power and Condensate Potentials
We study the cosmological evolution of scalar fields that arise from a phase
transition at some energy scale \Lm_c. We focus on negative power potentials
given by V=c\Lm_c^{4+n}\phi^{-n} and restrict the cosmological viable values
of \Lm_c and . We make a complete analysis of and impose
conditions on the different cosmological parameters. The cosmological
observations ruled out models where the scalar field has reached its attractor
solution. For models where this is not the case, the analytic approximated
solutions are not good enough to determine whether a specific model is
phenomenologically viable or not and the full differential equations must be
numerically solved. The results are not fine tuned since a change of 45% on the
initial conditions does not spoil the final results. We also determine the
values of that give a condensation scale \Lm_c consistent with
gauge coupling unification, leaving only four models that satisfy unification
and SN1a constraints.Comment: 15 pages, LaTeX, 8 Figures. Minor changes in text, a discussion on
initial conditions added (accepted in Phys.Rev.D
Comments on orientifold projection in the conifold and SO x USp duality cascade
We study the O3-plane in the conifold. On the D3-brane world-volume we obtain
SO x USp gauge theory that exhibits a duality cascade phenomenon. The
orientifold projection is determined on the type IIB string side, and
corresponds to that of O4-plane on the dual type IIA side. We show that SUGRA
solutions of Klebanov-Tseytlin and Klebanov-Strassler survive under the
projection. We also investigate the orientifold projection in the generalized
conifolds, and verify desired features of the O4-projection in the type IIA
picture.Comment: 1+27 pages, 9 figures, references added; version to appear in Phys.
Rev.