728 research outputs found
Strong Bounds on Sum of Neutrino Masses in a 12 Parameter Extended Scenario with Non-Phantom Dynamical Dark Energy ()
We obtained constraints on a 12 parameter extended cosmological scenario
including non-phantom dynamical dark energy (NPDDE) with CPL parametrization.
We also include the six CDM parameters, number of relativistic
neutrino species () and sum over active neutrino masses
(), tensor-to-scalar ratio (), and running of the
spectral index (). We use CMB Data from Planck 2015; BAO Measurements
from SDSS BOSS DR12, MGS, and 6dFS; SNe Ia Luminosity Distance measurements
from the Pantheon Sample; CMB B-mode polarization data from BICEP2/Keck
collaboration (BK14); Planck lensing data; and a prior on Hubble constant
( km/sec/Mpc) from local measurements (HST). We have found strong
bounds on the sum of the active neutrino masses. For instance, a strong bound
of 0.123 eV (95\% C.L.) comes from Planck+BK14+BAO. Although
we are in such an extended parameter space, this bound is stronger than a bound
of 0.158 eV (95\% C.L.) obtained in with Planck+BAO. Varying instead of
however leads to weaker bounds on . Inclusion of the HST leads to
the standard value of being discarded at more than
68\% C.L., which increases to 95\% C.L. when we vary
instead of , implying a small preference for dark radiation, driven
by the tension.Comment: 23 pages, 10 figures, matches the published versio
Enhanced tensor non-Gaussianities in presence of a source
We address the possibility of having an enhanced signal for tensor
non-Gaussianities in presence of a source, as a signature of Primordial
Gravitational Waves. We employ a nearly model-independent framework based on
Effective Field Theory of inflation and compute tensor non-Gaussianities
therefrom sourced by particle production during (p)reheating to arrive at an
enhanced signal strength. We obtain the model-independent non-linearity
parameters and also find that squeezed limit bispectra are more enhanced than
equilateral limit.Comment: 8 pages, 2 figures, Typos corrected, Minor modification
Generic 3-point Statistics with Tensor Modes in Light of Swampland and TCC
Recently proposed Swampland Criteria (SC) and Trans-Planckian Censorship
Conjecture (TCC) together put stringent theoretical constraints on slow roll
inflation, raising a question on future prospects of detection of Primordial
Gravitational Waves (PGW). As it appears, the only option to relax the
constraints is by considering Non Bunch Davies (NBD) initial states, that in
turn brings back the observational relevance of PGW via its 2-point function.
In this article we develop consistent 3-point statistics with tensor modes for
all possible correlators (auto and mixed) for NBD initial states in the light
of SC and TCC in a generic, model independent framework of Effective Field
Theory of inflation. We also construct the templates of the corresponding
nonlinearity parameters for different shapes of relevance and
investigate if any of the 3-point correlators could be of interest for future
CMB missions. Our analysis reveals that the prospects of detecting the tensor
auto correlator are almost nil whereas the mixed correlators might be relevant
for future CMB missions.Comment: 20 pages, 1 figur
Effective field theory of magnetogenesis: Identifying the necessary and sufficient conditions
At all Universe scales, there is a detectable amount of magnetic field. There
are several probable origins for this observed magnetic field, including the
possibility of its origin in the early Universe. There are several models for
primordial magnetogenesis, and if the inflationary background is taken into
account, breaking conformal symmetry is required to generate a sufficient
amount of magnetic field. The conformal symmetry breaking is introduced either
by new couplings between electromagnetic field and inflaton field or including
higher derivative terms to the theory. To unify these different approaches in
the literature, we propose an Effective Field Theory (EFT) approach, where EFT
parameters describe the magnetogenesis scenario in the early Universe, and
different choices of parameters correspond to different models. We show that
the vector perturbations do not have temporal evolution; hence, only the gauge
field is the relevant gauge-invariant variable for the EFT. We explicitly show
that the generation of primordial magnetic fields requires two necessary
conditions -- conformal invariance breaking and causal propagation. Hence,
conformal invariance breaking is only a necessary condition, \emph{not} a
sufficient condition. We confirm this by considering a specific model of
primordial magnetogenesis.Comment: 37 pages, 2 figure
Growth of curvature perturbations for PBH formation & detectable GWs in non-minimal curvaton revisited
We revisit the growth of curvature perturbations in non-minimal curvaton
scenario with a non-trivial field metric where is an
inflaton field, and incorporate the effect from the non-uniform onset of
curvaton's oscillation in terms of an axion-like potential. The field metric
plays a central role in the enhancement of curvaton field
perturbation , serving as an effective friction term which can be
either positive or negative, depending on the shape of , namely
the first derivative . Our analysis reveals that
undergoes the superhorizon growth when the condition is
satisfied. This is analogous to the mechanism responsible for the amplification
of curvature perturbations in the context of ultra-slow-roll inflation, namely
the growing modes dominate curvature perturbations. As a case study, we examine
the impact of a Gaussian dip in and conduct a thorough
investigation of both the analytical and numerical aspects of the inflationary
dynamics.Our findings indicate that the behavior of the curvaton perturbation
during inflation is not solely determined by the depth of the dip in
. Rather, the shape of the dip also plays a significant role, a
feature that has not been previously highlighted in the literature.Utilizing
the formalism, we derive analytical expressions for both
the final curvature power spectrum and the non-linear parameter
in terms of an axion-like curvaton's potential leading to the non-uniform
curvaton's oscillation.Additionally, the resulting primordial black hole
abundance and scalar-induced gravitational waves are calculated, which provide
observational windows for PBHs.Comment: 23 pages, 9 figure
- …