In order to expand the astrophysical reach of gravitational wave (GW) detectors, several
interferometer topologies have been proposed, in the past, to evade the thermodynamic
and quantum mechanical limits in future detectors. In this work, we make a systematic
comparison among these topologies by considering their sensitivities and complexities.
We numerically optimize their sensitivities by introducing a cost function that tries
to maximize the broadband improvement over the sensitivity of current detectors. We
find that frequency-dependent squeezed-light injection with a 100 m scale filter cavity
yields a good broadband sensitivity, with low complexity, and good robustness against
optical loss. This study gives us a guideline for the near-term experimental research
programs in enhancing the performance of future GW detectors. (paper)$$$$

Cosmological and astrophysical constraints on superconducting cosmic strings http://dx.doi.org/10.1088/1475-7516/2013/07/012 by Miyamoto, Koichi (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa
277-8582 (Japan)); Nakayama, Kazunori (Department of Physics, University of Tokyo,
Bunkyo-ku, Tokyo 113-0033 (Japan)), E-mail: miyamone@icrr.u-tokyo.ac.jp, E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp Read MoreCollapse

[en]

We investigate the cosmological and astrophysical constraints on superconducting cosmic
strings (SCSs). SCS loops emit strong bursts of electromagnetic waves, which might
affect various cosmological and astrophysical observations. We take into account the
effect on the CMB anisotropy, CMB blackbody spectrum, BBN, observational implications
on radio wave burst and X-ray or γ-ray events, and stochastic gravitational wave background
measured by pulsar timing experiments. We then derive constraints on the parameters
of SCS from current observations and estimate prospects for detecting SCS signatures
in on-going observations. As a result, we find that these constraints exclude broad
parameter regions, and also that on-going radio wave observations can probe large
parameter space$$$$

Conserved charges of black holes in Weyl and Einstein-Gauss-Bonnet gravities http://dx.doi.org/10.1140/epjc/s10052-014-3156-0 by Peng, Jun-Jin (SEEE, Wuhan Textile University, Institute of Technical Physics, Wuhan,
Hubei (China); Chinese Academy of Sciences, Kavli Institute for Theoretical Physics
China, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)) Read MoreCollapse

[en]

An off-shell generalization of the Abbott-Deser-Tekin (ADT) conserved charge was recently
proposed by Kim et al. They achieved this by introducing off-shell Noether currents
and potentials. In this paper, we construct the crucial off-shell Noether current
by the variation of the Bianchi identity for the expression of EOM, with the help
of the property of Killing vector. Our Noether current, which contains an additional
term that is just one half of the Lie derivative of a surface term with respect to
the Killing vector, takes a different form in comparison with the one in their work.
Then we employ the generalized formulation to calculate the quasi-local conserved
charges for the most general charged spherically symmetric and the dyonic rotating
black holes with AdS asymptotics in four-dimensional conformal Weyl gravity, as well
as the charged spherically symmetric black holes in arbitrary dimensional Einstein-Gauss-Bonnet
gravity coupled to Maxwell or nonlinear electrodynamics in AdS spacetime. Our results
confirm those obtained through other methods in the literature. (orig.)$$$$

Solid inflation http://dx.doi.org/10.1088/1475-7516/2013/10/011 by Endlich, Solomon; Nicolis, Alberto; Wang, Junpu (Department of Physics and ISCAP,
Columbia University, New York, NY 10027 (United States)), E-mail: solomon@phys.columbia.edu,
E-mail: nicolis@phys.columbia.edu, E-mail: junpu@phys.columbia.edu Read MoreCollapse

[en]

We develop a cosmological model where primordial inflation is driven by a 'solid',
defined as a system of three derivatively coupled scalar fields obeying certain symmetries
and spontaneously breaking a certain subgroup of these. The symmetry breaking pattern
differs drastically from that of standard inflationary models: time translations are
unbroken. This prevents our model from fitting into the standard effective field theory
description of adiabatic perturbations, with crucial consequences for the dynamics
of cosmological perturbations. Most notably, non-gaussianities in the curvature perturbations
are unusually large, with f_{NL} ∼ 1/(εc_{s}^{2}), and have
a novel shape: peaked in the squeezed limit, with anisotropic dependence on how the
limit is approached. Other unusual features include the absence of adiabatic fluctuation
modes during inflation — which does not impair their presence and near scale-invariance
after inflation — and a slightly blue tilt for the tensor modes$$$$

Interacting warm dark matter http://dx.doi.org/10.1088/1475-7516/2013/05/034 by Cruz, Norman; Palma, Guillermo; Zambrano, David (Departamento de Física, Facultad
de Ciencia, Universidad de Santiago de Chile, Casilla 307, Santiago (Chile)); Avelino,
Arturo (Departamento de Física, DCI, Campus León, Universidad de Guanajuato, CP. 37150,
León, Guanajuato (Mexico)), E-mail: norman.cruz@usach.cl, E-mail: guillermo.palma@usach.cl,
E-mail: david.zambrano@gmail.com, E-mail: avelino@fisica.ugto.mx Read MoreCollapse

[en]

We explore a cosmological model composed by a dark matter fluid interacting with a
dark energy fluid. The interaction term has the non-linear λρ_{m}^{α}ρ_{e}^{β}
form, where ρ_{m} and ρ_{e} are the energy densities of the dark matter
and dark energy, respectively. The parameters α and β are in principle not constrained
to take any particular values, and were estimated from observations. We perform an
analytical study of the evolution equations, finding the fixed points and their stability
properties in order to characterize suitable physical regions in the phase space of
the dark matter and dark energy densities. The constants (λ,α,β) as well as w_{m}
and w_{e} of the EoS of dark matter and dark energy respectively, were estimated
using the cosmological observations of the type Ia supernovae and the Hubble expansion
rate H(z) data sets. We find that the best estimated values for the free parameters
of the model correspond to a warm dark matter interacting with a phantom dark energy
component, with a well goodness-of-fit to data. However, using the Bayesian Information
Criterion (BIC) we find that this model is overcame by a warm dark matter – phantom
dark energy model without interaction, as well as by the ΛCDM model. We find also
a large dispersion on the best estimated values of the (λ,α,β) parameters, so even
if we are not able to set strong constraints on their values, given the goodness-of-fit
to data of the model, we find that a large variety of theirs values are well compatible
with the observational data used$$$$

Cosmography with the Sunyaev-Zeldovich effect and X-ray data http://dx.doi.org/10.1088/1475-7516/2013/06/033 by Holanda, R.F.L. (Departamento de Física, Universidade Estadual da Paraíba, 58429-500,
Campina Grande - PB (Brazil)); Alcaniz, J.S.; Carvalho, J.C. (Departamento de Astronomia,
Observatório Nacional, 20921-400, Rio de Janeiro - RJ (Brazil)), E-mail: holanda@uepb.edu.br,
E-mail: alcaniz@on.br, E-mail: carvalho@dfte.ufrn.br Read MoreCollapse

[en]

Cosmography provides a direct method to map the expansion history of the Universe
in a model-independent way. Recently, different kinds of observations have been used
in cosmographic analyses, such as SNe Ia and gamma ray bursts measurements, weak and
strong lensing, cosmic microwave background anisotropies, etc. In this work we examine
the prospects for constraining cosmographic parameters from current and future measurements
of galaxy clusters distances based on their Sunyaev-Zeldovich effect (SZE) and X-ray
observations. By assuming the current observational error distribution, we perform
Monte Carlo simulations based on a well-behaved parameterization for the deceleration
parameter to generate samples with different characteristics and study the improvement
on the determination of the cosmographic parameters from upcoming data. The influence
of galaxy clusters (GC) morphologies on the H_{0}−q_{0} plane is also
investigated$$$$

Realistic fission model and the r-process in neutron star mergers http://dx.doi.org/10.1063/1.4875313 by Shibagaki, S.; Kajino, T. (Department of Astronomy, Graduate School of Science, University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan and National Astronomical
Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)); Chiba, S. (Research
Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku,
Tokyo, 152-8850 (Japan)); Mathews, G. J. (Center for Astrophysics, Department of Physics,
University of Notre Dame, IN 46556, U.S.A. and National Astronomical Observatory of
Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)) Read MoreCollapse

[en]

About half of heavy elements are considered to be produced by the rapid neutron-capture
process, r-process. The neutron star merger is one of the viable candidates for the
astrophysical site of r-process nucleosynthesis. Nuclear fission reactions play an
important role in the r-process of neutron star mergers. However theoretical predictions
about fission properties of neutron-rich nuclei have some uncertainties. Especially,
their fission fragment distributions are totally unknown and the phenomenologically
extrapolated distribution was often applied to nucleosynthesis calculations. In this
study, we have carried out r-process nucleosynthesis calculations based upon new theoretical
estimates of fission fragment distributions. We discuss the effects on the r-process
in neutron star mergers from the nuclear fission of heavy neutron-rich actinide elements.
We also discuss how variations in the fission fragment distributions affect the abundance
pattern$$$$

Gradient expansion of superhorizon perturbations in G-inflation http://dx.doi.org/10.1088/1475-7516/2013/07/020 by Frusciante, Noemi; Zhou, Shuang-Yong; Sotiriou, Thomas P. (SISSA and INFN Sezione
di Trieste, Via Bonomea 265, 34136, Trieste (Italy)), E-mail: nfruscia@sissa.it, E-mail:
szhou@sissa.it, E-mail: sotiriou@sissa.it Read MoreCollapse

[en]

We develop the gradient expansion formalism for shift-symmetric Galileon-type actions.
We focus on backgrounds that undergo inflation, work in the synchronous gauge, and
obtain a general solution up to second order without imposing extra conditions at
first order. The solution simplifies during the late stages of inflation. We also
define a curvature perturbation conserved up to first order$$$$

Universality class in conformal inflation http://dx.doi.org/10.1088/1475-7516/2013/07/002 by Kallosh, Renata; Linde, Andrei (Department of Physics and SITP, Stanford University,
Stanford, California 94305 (United States)), E-mail: kallosh@stanford.edu, E-mail:
alinde@stanford.edu Read MoreCollapse

[en]

We develop a new class of chaotic inflation models with spontaneously broken conformal
invariance. Observational consequences of a broad class of such models are stable
with respect to strong deformations of the scalar potential. This universality is
a critical phenomenon near the point of enhanced symmetry, SO(1,1), in case of conformal
inflation. It appears because of the exponential stretching of the moduli space and
the resulting exponential flattening of scalar potentials upon switching from the
Jordan frame to the Einstein frame in this class of models. This result resembles
stretching and flattening of inhomogeneities during inflationary expansion. It has
a simple interpretation in terms of velocity versus rapidity near the Kähler cone
in the moduli space, similar to the light cone of special theory of relativity. This
effect makes inflation possible even in the models with very steep potentials. We
describe conformal and superconformal versions of this cosmological attractor mechanism$$$$