3 research outputs found
Scalar induced gravity waves from ultra slow-roll Galileon inflation
We consider the production of secondary gravity waves in Galileon inflation
with an ultra-slow roll (USR) phase and show that the spectrum of
scalar-induced gravitational waves (SIGWs) in this case is consistent with the
recent NANOGrav 15-year data and with sensitivities of other ground and
space-based missions, LISA, BBO, DECIGO, CE, ET, HLVK (consists of aLIGO,
aVirgo, and KAGRA), and HLV(03). Thanks to the non-renormalization property of
Galileon theory, the amplitude of the large fluctuation is controllable at the
sharp transitions between SR and USR regions. We show that the behaviour of the
GW spectrum, when one-loop effects are included in the scalar power spectrum,
is preserved under a shift of the sharp transition scale with peak amplitude
, and hence it can cover a wide range
of frequencies within . An analysis
of the allowed mass range for primordial black holes (PBHs) is also performed,
where we find that mass values ranging from can be generated over the corresponding allowed range of
low and high frequencies.Comment: 25 pages, 2 figures, Comments are welcom
Primordial non-Gaussianity as a saviour for PBH overproduction in SIGWs generated by Pulsar Timing Arrays for Galileon inflation
We investigate the explicit role of negative local non-Gaussianity, , in suppressing the abundance of primordial black holes (PBHs) in the
single-field model of Galileon inflation. PBH formation requires significantly
enhancing the scalar power spectrum, which greatly affects their abundance. The
associated frequencies in the nHz regime are also sensitive to the generation
of scalar-induced gravitational waves (SIGWs) which may explain the current
data from the pulsar timing arrays (PTAs). Our analysis using the threshold
statistics on the compaction function demonstrates that Galileon theory not
only avoids PBH overproduction using the curvature perturbation enhancements
that give , but also generates SIGWs that conform
well with the PTA data.Comment: 20 pages (5 pages material+8 pages refs.+7 pages supplementary
material), 5 figures (3 figures in material+2 figures in supplementary
material), Comments are welcome, Reference list update
Evading no-go for PBH formation and production of SIGWs using Multiple Sharp Transitions in EFT of single field inflation
Deploying \textit{multiple sharp transitions} (MSTs) under a unified
framework, we investigate the formation of Primordial Black Holes (PBHs) and
the production of Scalar Induced Gravitational Waves (SIGWs) by incorporating
one-loop corrected renormalized-resummed scalar power spectrum. With effective
sound speed parameter, , the direct consequence is the
generation of PBH masses spanning , thus evading well known \textit{No-go theorem} on PBH mass.
Our results align coherently with the extensive NANOGrav 15-year data and the
sensitivities outlined by other terrestrial and space-based experiments (e.g.:
LISA, HLVK, BBO, HLV(O3), etc.).Comment: 14 pages, 3 figures, Comments are welcom