Introduces weight-shifting matrices for de Sitter diagrams, generalized with Kronecker products to arbitrary tree-level graphs, to derive massless wavefunction coefficients from conformally coupled seeds.
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Formalising the Slow-Roll Approximation in Inflation
14 Pith papers cite this work. Polarity classification is still indexing.
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abstract
The meaning of the inflationary slow-roll approximation is formalised. Comparisons are made between an approach based on the Hamilton-Jacobi equations, governing the evolution of the Hubble parameter, and the usual scenario based on the evolution of the potential energy density. The vital role of the inflationary attractor solution is emphasised, and some of its properties described. We propose a new measure of inflation, based upon contraction of the comoving Hubble length as opposed to the usual e-foldings of physical expansion, and derive relevant formulae. We introduce an infinite hierarchy of slow-roll parameters, and show that only a finite number of them are required to produce results to a given order. The extension of the slow-roll approximation into an analytic slow-roll expansion, converging on the exact solution, is provided. Its role in calculations of inflationary dynamics is discussed. We explore rational-approximants as a method of extending the range of convergence of the slow-roll expansion up to, and beyond, the end of inflation.
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In pure axion inflation, detectable gravitational wave signals arise only in parameter regions with strong backreaction that violate the upper bound on ΔN_eff.
LLM embeddings condition a generative transformer to enable faster convergence, better performance, and generalization to unseen LHC processes using a single model.
A new eigenvalue method is introduced to compute the PDF of stochastic e-folds in inflation, recovering a known flat-potential result and analyzing constant-drift cases in narrow and broad well limits.
Improved end-of-inflation dynamics shift the Starobinsky model's predicted spectral index n_s by up to 1.2×10^{-3} within the allowed reheating range.
Breaking diffeomorphism invariance to transverse diffeomorphisms in the inflaton sector yields modified slow-roll parameters and power spectra with novel post-inflationary regimes for quadratic potentials.
A dark U(1)_D model with dark Higgs inflation and low reheating allows dark photon dark matter to achieve the observed relic density for a wider range of couplings, with inflation predictions matching Planck, BICEP/Keck and ACT data.
Authors add induced gravity and a polynomial potential to an F(R) model, transform to a two-field chiral cosmology, and find parameter choices that match ACT inflation data while yielding PBH masses compatible with dark matter.
Einstein-Cartan pseudoscalaron inflation coupled to type-I seesaw neutrinos makes nonthermal leptogenesis a necessary mechanism for the baryon asymmetry, yielding ns ~ 0.97, r ~ 0.004 and nB/s ~ 8.7e-11 for gamma ~ -1/100 and lightest Majorana mass ~ 10^13 GeV.
A power-law non-canonical kinetic coupling F(φ)=1+Aφ^n revives the Starobinsky inflation potential's consistency with ACT DR6 CMB data while preserving attractor dynamics and yielding viable reheating.
Authors introduce new Hubble rate test functions for tachyon inflation, derive analytical ns and r using assumed slow-roll parameter dependence, and compare predictions to Planck data.
Several terms in the third-order slow-roll power spectra are incorrect because three-dimensional integrals were evaluated by integrating a truncated Taylor expansion instead of Taylor-expanding the integral.
Numerical demonstration that a revised multimeasure multifield model with effective friction can describe the entire Universe evolution from inflation to late-time constant scalar field.
A tutorial deriving cosmological perturbation equations from inflation through reheating, with explicit gauge-invariant computations and Python scripts.
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Cosmological Weight-Shifting Matrices
Introduces weight-shifting matrices for de Sitter diagrams, generalized with Kronecker products to arbitrary tree-level graphs, to derive massless wavefunction coefficients from conformally coupled seeds.
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Gravitational waves from axion inflation in the gradient expansion formalism. Part I. Pure axion inflation
In pure axion inflation, detectable gravitational wave signals arise only in parameter regions with strong backreaction that violate the upper bound on ΔN_eff.
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One Generator, Any Process: LLM-Conditioning for the LHC
LLM embeddings condition a generative transformer to enable faster convergence, better performance, and generalization to unseen LHC processes using a single model.
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Eigenvalue formulation of Stochastic Inflation and application to large perturbation generating inflationary features
A new eigenvalue method is introduced to compute the PDF of stochastic e-folds in inflation, recovering a known flat-potential result and analyzing constant-drift cases in narrow and broad well limits.
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Precision Inflationary Predictions: Impact of Accurate End-of-Inflation Dynamics
Improved end-of-inflation dynamics shift the Starobinsky model's predicted spectral index n_s by up to 1.2×10^{-3} within the allowed reheating range.
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Inflation in theories with broken diffeomorphisms
Breaking diffeomorphism invariance to transverse diffeomorphisms in the inflaton sector yields modified slow-roll parameters and power spectra with novel post-inflationary regimes for quadratic potentials.
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Low-reheating scenario in dark Higgs inflation and its impact on dark photon dark matter production
A dark U(1)_D model with dark Higgs inflation and low reheating allows dark photon dark matter to achieve the observed relic density for a wider range of couplings, with inflation predictions matching Planck, BICEP/Keck and ACT data.
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Primordial black holes formation in inflationary $F(R)$ models with scalar fields
Authors add induced gravity and a polynomial potential to an F(R) model, transform to a two-field chiral cosmology, and find parameter choices that match ACT inflation data while yielding PBH masses compatible with dark matter.
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Einstein-Cartan pseudoscalaron inflation, reheating and nonthermal leptogenesis
Einstein-Cartan pseudoscalaron inflation coupled to type-I seesaw neutrinos makes nonthermal leptogenesis a necessary mechanism for the baryon asymmetry, yielding ns ~ 0.97, r ~ 0.004 and nB/s ~ 8.7e-11 for gamma ~ -1/100 and lightest Majorana mass ~ 10^13 GeV.
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Starobinsky Inflation in k-Essence Framework: Attractor Dynamics, Reheating, and Consistency with ACT DR6
A power-law non-canonical kinetic coupling F(φ)=1+Aφ^n revives the Starobinsky inflation potential's consistency with ACT DR6 CMB data while preserving attractor dynamics and yielding viable reheating.
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Analytical calculation of the observational parameters for tachyon inflation
Authors introduce new Hubble rate test functions for tachyon inflation, derive analytical ns and r using assumed slow-roll parameter dependence, and compare predictions to Planck data.
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Comment on: "Third-order corrections to the slow-roll expansion: Calculation and constraints with Planck, ACT, SPT, and BICEP/Keck [2025 PDU 47 101813]"
Several terms in the third-order slow-roll power spectra are incorrect because three-dimensional integrals were evaluated by integrating a truncated Taylor expansion instead of Taylor-expanding the integral.
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Cosmology from multimeasure multifield model
Numerical demonstration that a revised multimeasure multifield model with effective friction can describe the entire Universe evolution from inflation to late-time constant scalar field.
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From inflation to hot big bang -- a tutorial on cosmological perturbations
A tutorial deriving cosmological perturbation equations from inflation through reheating, with explicit gauge-invariant computations and Python scripts.