A
bstract
Constant-rate inflation, including ultra-slow-roll inflation as a special case, has been widely applied to the formation of primordial black holes with a significant deviation from the ...standard slow-roll conditions at both the growing and decaying phases of the power spectrum. We derive analytic solutions for the curvature perturbations with respect to the late-time scaling dimensions (conformal weights) constrained by the dilatation symmetry of the de Sitter background and show that the continuity of conformal weights across different rolling phases is protected by the adiabatic condition of the inflaton perturbation. The temporal excitation of subleading states (with the next-to-lowest conformal weights), recorded as the “steepest growth” of the power spectrum, is triggered by the entropy production in the transition from the slow-roll to the constant-rate phases.
We study the polarizations induced by the Galileon as a stochastic gravitational wave background in the cross correlated power in a pulsar timing array. Working within Galileon gravity, we first show ...that the scalar gravitational wave signature of the Galileon is encoded solely in its effective mass, which is controlled by the bare mass, conformal coupling, and a tadpole. Then, we study the phenomenology of the Galileon induced scalar polarizations and place observational constraints on these using the present NANOGrav data set. Our results feature longitudinal spatial correlation, indicative of a 10−22 eV subluminal Galileon, and show the Galileon polarizations as a statistically compelling source of the observed spatial correlation across millisecond pulsars, if there is any.
We develop a nonperturbative method through the Hartree factorization to examine the quantum fluctuation effects on the single-field inflationary models in a spatially flat FRW cosmological ...space-time. Apart from the background field equation as well as the Friedmann equation with the corrections of quantum field fluctuations, the modified Mukhanov-Sasaki equations for the mode functions of the quantum scalar field are also derived by introducing the nonzero ΔB term. We consider the Universe undergoing the slow roll (SR)-ultra slow roll (USR) -slow roll (SR) inflation where in particular the presence of the USR inflation triggers the huge growth of ΔB that in turn gives the boost effects to the curvature perturbations for the modes that leave horizon in the early times of the inflation. However, the cosmic friction term in the mode equation given by the Hubble parameter presumably prohibits the boost effects. Here we propose two representative models to illustrate these two competing terms.
In this paper, we show that single-field chaotic inflation on the brane with the potential V=aϕp is compatible with the swampland criteria. The spectral index and the running spectral index are ...within experimental bounds for 0<p≤2. The tensor to scalar ratio is within observational bounds if p≲O(1).
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