442 research outputs found
String in Horava-Lifshitz Gravity
We generalize recent analysis of the dynamics of point particle in
Horava-Lifshitz background to the case of string probe when we replace the
Hamiltonian constraint of the Polyakov string with the constraint that breaks
Lorentz invariance of target space-time. Then we find corresponding Lagrangian
and argue that the world-sheet theory is invariant under foliation preserving
diffeomorphism. Finally we discuss the Hamiltonian dynamics and show that this
is well defined on condition that the world-sheet lapse function obeys the
projectability condition.Comment: 20 pages, references adde
Black hole solutions in Horava-Lifshitz Gravity with cubic terms
We study four dimensional non-projectable Horava-Lifshitz type gravity, in
the case of an action with terms, cubic in curvature. For special choices of
the free parameters of the model, we obtain two new analytic black hole
solutions which exhibit the standard Schwarzschild asymptotic behavior in the
large distance limit. The effect of cubic terms in the short range behavior of
the black hole solutions is discussed.Comment: 25 pages, 3 figures, accepted in Phys. Rev.
Liouville-Lifshitz theory in 3+1 dimensions
We consider a four-dimensional theory in the z=3 Lifshitz context, with an
exponential (Liouville) potential. We determine the exact renormalized
potential of the theory and derive the non-perturbative relation between the
renormalized and bare couplings. In addition, we show that Lorentz symmetry is
naturally generated by quantum fluctuations in the infrared regime, and
conclude that the model can be relevant to High Energy Physics
Developing and exploiting linguistic resources in research and in the didactics of Specialised Translation
This paper outlines the main state-of-the-art linguistic resources that can be developed and used in the research and in the didactics of Specialised Translation. In addition, it points to the still largely unexplored potential from the combination of Corpus Linguistics, Descriptive Translation Studies and Systemic Functional Linguistics into a single scientific and research agenda, to the benefit of both translation practitioners and trainee translators.
Viable f(T) models are practically indistinguishable from LCDM
We investigate the cosmological predictions of several models, with up
to two parameters, at both the background and the perturbation levels. Using
current cosmological observations (geometric supernovae type Ia, cosmic
microwave background and baryonic acoustic oscillation and dynamical growth
data) we impose constraints on the distortion parameter, which quantifies the
deviation of these models from the concordance cosmology at the
background level. In addition we constrain the growth index predicted
in the context of these models using the latest perturbation growth data in the
context of three parametrizations for . The evolution of the best fit
effective Newton constant, which incorporates the -gravity effects, is
also obtained along with the corresponding error regions. We show
that all the viable parameter sectors of the gravity models considered
practically reduce these models to CDM. Thus, the degrees of freedom
that open up to CDM in the context of gravity models are not
utilized by the cosmological data leading to an overall disfavor of these
models.Comment: 16 pages, 9 figures, changes match published versio
Power spectra from an inflaton coupled to the Gauss-Bonnet term
We consider power-law inflation with a Gauss-Bonnet correction inspired by
string theory. We analyze the stability of cosmological perturbations and
obtain the allowed parameter space. We find that for GB-dominated inflation
ultra-violet instabilities of either scalar or tensor perturbations show up on
small scales. The Gauss-Bonnet correction with a positive (or negative)
coupling may lead to a reduction (or enhancement) of the tensor-to-scalar ratio
in the potential-dominated case. We place tight constraints on the model
parameters by making use of the WMAP 5-year data.Comment: 5 pages, 4 figures, RevTeX, references added, published versio
Developing and exploiting linguistic resources in research and in the didactics of Specialised Translation
This paper outlines the main state-of-the-art linguistic resources that can be developed and used in the research and in the didactics of Specialised Translation. In addition, it points to the still largely unexplored potential from the combination of Corpus Linguistics, Descriptive Translation Studies and Systemic Functional Linguistics into a single scientific and research agenda, to the benefit of both translation practitioners and trainee translators.
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