4,797 research outputs found
On the emergence of the CDM model from self-interacting Brans-Dicke theory in
We investigate whether a self-interacting Brans-Dicke theory in without
matter and with a time-dependent metric can describe, after dimensional
reduction to , the FLRW model with accelerated expansion and
non-relativistic matter. By rewriting the effective 4-dimensional theory as an
autonomous three-dimensional dynamical system and studying its critical points,
we show that the CDM cosmology cannot emerge from such a model. This
result suggests that a richer structure in may be needed to obtain the
accelerated expansion as well as the matter content of the 4-dimensional
universe.Comment: 7 pages, 7 figure
Physics of Brane Kinetic Terms
Models with extra dimensions may give new effects visible at future
experiments. In these models, bulk fields can develop localized corrections to
their kinetic terms which can modify the phenomenological predictions in a
sizeable way. We review the case in which both gauge bosons and fermions
propagate in the bulk, and discuss the limits on the parameter space arising
from electroweak precision data.Comment: Presented at Matter To The Deepest: Recent Developments In Physics of
Fundamental Interactions, XXVII International Conference of Theoretical
Physics, Ustron 15-21 September 2003, Polan
Bulk fields with brane terms
In theories with branes, bulk fields get in general divergent corrections
localized on these defects. Hence, the corresponding brane terms are
renormalized and should be included in the effective theory from the very
beginning. We review the phenomenology associated to brane kinetic terms for
different spins and backgrounds, and point out that renormalization is required
already at the classical level.Comment: Presented at HEP2003, International Europhysics Conference on High
Energy Physics (July 17-23, 2003) Aachen, German
Observable contributions of new exotic quarks to quark mixing
Models with new vector-like quarks can produce observable quark mixing
effects which are forbidden in the Standard Model. We classify all such models
and write down the effective Lagrangian that results from integrating out the
new quarks. We study the relations between neutral and charged currents and
discuss how to distinguish among the different possibilities.Comment: 15 pages, 1 figure, typos corrected, version to appear in JHE
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