2,694 research outputs found
Modified f(R) gravity from scalar-tensor theory and inhomogeneous EoS dark energy
The reconstruction of f(R)-gravity is showed by using an auxiliary scalar
field in the context of cosmological evolution, this development provide a way
of reconstruct the form of the function f (R) for a given evolution of the
Hubble parameter. In analogy, f(R)-gravity may be expressed by a perfect fluid
with an inhomogeneous equation of state that depends on the Hubble parameter
and its derivatives. This mathematical equivalence that may confuse about the
origin of the mechanism that produces the current acceleration, and possibly
the whole evolution of the Hubble parameter, is shown here.Comment: 8 page
Tachyon fields with effects of quantum matter in an Anti-de Sitter Universe
We consider an Anti-de Sitter universe filled by quantum conformal matter
with the contribution from the usual tachyon and a perfect fluid. The model
represents the combination of a trace-anomaly annihilated and a tachyon driven
Anti-de Sitter universe. The influence exerted by the quantum effects and by
the tachyon on the AdS space is studied. The radius corresponding to this
universe is calculated and the effect of the tachyon potential is discussed, in
particular, concerning to the possibility to get an accelerated scale factor
for the proposed model (implying an accelerated expansion of the AdS type of
universe). Fulfillment of the cosmological energy conditions in the model is
also investigatedComment: 14 Latex pages, no figure
Cosmological solutions in F(R) Horava-Lifshitz gravity
At the present work, it is studied the extension of F (R) gravities to the
new recently proposed theory of gravity, the so-called Horava-Lifshitz gravity,
which provides a way to make the theory power counting renormalizable by
breaking Lorentz invariance. It is showed that dark energy can be well
explained in the frame of this extension, just in terms of gravity. It is also
explored the possibility to unify inflation and late-time acceleration under
the same mechanism, providing a natural explanation the accelerated expansion.Comment: 4 pages. Contribution to the Proceedings of the Spanish Relativity
Meeting (ERE) 2010, Granada, Spai
Study of the slepton non-universality at the CERN Large Hadron Collider
In supersymmetric theory, the sfermion-fermion-gaugino interactions conserve
the chirality of (s)fermions. The effect appears as the charge asymmetry in
distributions at the CERN Large Hadron Collider where jets and leptons
arise from the cascade decay . Furthermore, the decay branching ratios and the charge
asymmetries in distributions are flavor non-universal due to the
and mixing. When is large, the
non-universality between and becomes level. We perform a
Monte Carlo simulation for some minimal supergravity benchmark points to
demonstrate the detectability.Comment: 19 pages, 6 figures, revte
Implications of Muon anomalous magnetic moment for Direct detection of Neutralino Dark Matter
We investigate the implications of the recent measurement of muon anomalous
magnetic moment for the direct detection of neutralino dark matter in the three
different SUSY models: mSUGRA, a model with non-universal Higgs mass, and an
SO(10) GUT model. We consider two extreme scenario for bound,
i.e. (1 bound)
and ( below). In mSUGRA model,
the counting ratio may be above the sensitivity of the future experiments when
parameters are within bound of . However, the
tends to be high compared to the currently favored value
. For models with the non-universal scalar masses, the possibility
to have the consistent and the high counting ratio is open up
in the region of parameter space where Higgsino mass is smaller than
mSUGRA prediction. In particular, in the SO(10) model, the LSP dark matter
detection rate may be enhanced by almost one order of magnitude compared to
mSUGRA and the model with non-universal Higgs mass, for cosmologically
acceptable . The highest detection rate of LSP dark matter
occurs in the region where the LSP constitutes a subdominant part of local halo
DM. Implication of SUSY mass parameter measurement under the cosmological
constraint is also discussed
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