2,632 research outputs found
Systematic treatment of non-linear effects in Baryon Acoustic Oscillations
In this contribution we will discuss the non-linear effects in the baryon
acoustic oscillations and present a systematic and controllable way to account
for them within time-sliced perturbation theory.Comment: 8 pages, 5 figures; to appear in the Proceedings of the 19th
International Seminar on High Energy Physics QUARKS-2016, Pushkin, Russia, 29
May - 4 June, 201
Time-Sliced Perturbation Theory for Large Scale Structure I: General Formalism
We present a new analytic approach to describe large scale structure
formation in the mildly non-linear regime. The central object of the method is
the time-dependent probability distribution function generating correlators of
the cosmological observables at a given moment of time. Expanding the
distribution function around the Gaussian weight we formulate a perturbative
technique to calculate non-linear corrections to cosmological correlators,
similar to the diagrammatic expansion in a three-dimensional Euclidean quantum
field theory, with time playing the role of an external parameter. For the
physically relevant case of cold dark matter in an Einstein--de Sitter
universe, the time evolution of the distribution function can be found exactly
and is encapsulated by a time-dependent coupling constant controlling the
perturbative expansion. We show that all building blocks of the expansion are
free from spurious infrared enhanced contributions that plague the standard
cosmological perturbation theory. This paves the way towards the systematic
resummation of infrared effects in large scale structure formation. We also
argue that the approach proposed here provides a natural framework to account
for the influence of short-scale dynamics on larger scales along the lines of
effective field theory.Comment: 29 pages, 2 figures, discussion on IR safety expanded, appendix C
added; version published in JCA
Time-Sliced Perturbation Theory II: Baryon Acoustic Oscillations and Infrared Resummation
We use time-sliced perturbation theory (TSPT) to give an accurate description
of the infrared non-linear effects affecting the baryonic acoustic oscillations
(BAO) present in the distribution of matter at very large scales. In TSPT this
can be done via a systematic resummation that has a simple diagrammatic
representation and does not involve uncontrollable approximations. We discuss
the power counting rules and derive explicit expressions for the resummed
matter power spectrum up to next-to leading order and the bispectrum at the
leading order. The two-point correlation function agrees well with N-body data
at BAO scales. The systematic approach also allows to reliably assess the shift
of the baryon acoustic peak due to non-linear effects.Comment: 38 pages + 24 pages of appendices and references, 8 figures;
comparison with the Zel'dovich approximation added (Fig.8); version published
in JCA
On constraining the speed of gravitational waves following GW150914
We point out that the observed time delay between the detection of the signal
at the Hanford and Livingston LIGO sites from the gravitational wave event
GW150914 places an upper bound on the speed of propagation of gravitational
waves, in the units of speed of light. Combined with the
lower bound from the absence of gravitational Cherenkov losses by cosmic rays
that rules out most of subluminal velocities, this gives a model-independent
double-sided constraint . We compare this result
to model-specific constraints from pulsar timing and cosmology.Comment: 3 pages, 1 figure, references adde
Scalar Love numbers and Love symmetries of 5-dimensional Myers-Perry black hole
The near-zone ``Love'' symmetry resolves the naturalness issue of black hole
Love number vanishing with representation
theory. Here, we generalize this proposal to -dimensional asymptotically
flat and doubly spinning (Myers-Perry) black holes. We consider the scalar
response of Myers-Perry black holes and extract its static scalar Love numbers.
In agreement with the naturalness arguments, these Love numbers are, in
general, non-zero and exhibit logarithmic running unless certain resonant
conditions are met; these conditions include new cases with no previously known
analogs. We show that there exist two near-zone truncations of the equations of
motion that exhibit enhanced Love
symmetries that explain the vanishing of the static scalar Love numbers in the
resonant cases. These Love symmetries can be interpreted as local
near-zone symmetries spontaneously broken down to global
symmetries by the
periodic identification of the azimuthal angles. We also discover an
infinite-dimensional extension of the Love symmetry into
that contains both Love symmetries as particular subalgebras, along with a
family of subalgebras that reduce to the
exact near-horizon Myers-Perry black hole isometries in the extremal limit.
Finally, we show that the Love symmetries acquire a geometric interpretation as
isometries of subtracted (effective) black hole geometries that preserve the
internal structure of the black hole and interpret these non-extremal
structures as remnants of the enhanced
isometry of the near-horizon extremal geometries.Comment: 45+16 pages, 3 Figure
UV-extending Ghost Inflation
We present a setup that provides a partial UV-completion of the ghost
inflation model up to a scale which can be almost as high as the Planck mass.
This is achieved by coupling the inflaton to the Lorentz-violating sector
described by the Einstein-aether theory or its khronometric version. Compared
to previous works on ghost inflation our setup allows to go beyond the study of
small perturbations and include the background dynamics in a unified framework.
In the specific regime when the expansion of the Universe is dominated by the
kinetic energy of the inflaton we find that the model predicts rather high
tensor-to-scalar ratio r ~ 0.02 0.2 and non-Gaussianity of equilateral
type with f_NL in the range from -50 to -5.Comment: 30 pages, 1 figure; the predicted range of observables explicitly
indicated in the abstract, footnote on the BICEP2 results added; version to
be published in JCA
Vanishing of black hole tidal Love numbers from scattering amplitudes
We extract the black hole (BH) static tidal deformability coefficients (Love
numbers) and their spin-0 and spin-1 analogs by comparing on-shell amplitudes
for fields to scatter off a spinning BH in the worldline effective field theory
(EFT) and in general relativity (GR). We point out that the GR amplitudes due
to tidal effects originate entirely from the BH potential region. Thus, they
can be separated from gravitational non-linearities in the wave region, whose
proper treatment requires higher order EFT loop calculations. In particular,
the elastic scattering in the near field approximation is produced exclusively
by tidal effects. We find this contribution to vanish identically, which
implies that the static Love numbers of Kerr BHs are zero for all types of
perturbations. We also reproduce the known behavior of scalar Love numbers for
higher dimensional BHs. Our results are manifestly gauge-invariant and
coordinate-independent, thereby providing a valuable consistency check for the
commonly used off-shell methods.Comment: 7 pages, 1 figure, comments are welcom
Combining Full-Shape and BAO Analyses of Galaxy Power Spectra: A 1.6% CMB-independent constraint on H0
We present cosmological constraints from a joint analysis of the pre- and
post-reconstruction galaxy power spectrum multipoles from the final data
release of the Baryon Oscillation Spectroscopic Survey (BOSS). Geometric
constraints are obtained from the positions of BAO peaks in reconstructed
spectra, analyzed in combination with the unreconstructed spectra in a
full-shape (FS) likelihood using a joint covariance matrix, giving stronger
parameter constraints than FS-only or BAO-only analyses. We introduce a new
method for obtaining constraints from reconstructed spectra based on a
correlated theoretical error, which is shown to be simple, robust, and
applicable to any flavor of density-field reconstruction. Assuming CDM
with massive neutrinos, we analyze data from two redshift bins
and obtain constraints on the Hubble
constant , using only a single prior on the current baryon density
from Big Bang Nucleosynthesis (BBN) and no knowledge of the power
spectrum slope . This gives , with the inclusion of BAO
data sharpening the measurement by , representing one of the strongest
current constraints on independent of cosmic microwave background data.
Restricting to the best-fit slope from Planck (but without additional
priors on the spectral shape), we obtain a measurement of . We find strong constraints on the
cosmological parameters from a joint analysis of the FS, BAO, and Planck data.
This sets new bounds on the sum of neutrino masses (at confidence) and the effective number of
relativistic degrees of freedom , though
contours are not appreciably narrowed by the inclusion of BAO data.Comment: 42 pages, 12 figures, accepted by JCAP, likelihoods available at
https://github.com/Michalychforever/lss_montepython (minor typo corrected
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