Tracking the Multifield Dynamics with Cosmological Data: A Monte Carlo approach

Abstract

We introduce a numerical method specifically designed for investigating generic multifield models of inflation where a number of scalar fields ${\varphi }^K$ are minimally coupled to gravity and live in a field space with a non-trivial metric $G_{IJ}({\varphi }^K)$. Our algorithm consists of three main parts. Firstly, we solve the field equations through the entire inflationary period, deriving predictions for observable quantities such as the spectrum of scalar perturbations, primordial gravitational waves, and isocurvature modes. We also incorporate the transfer matrix formalism to track the behavior of adiabatic and isocurvature modes on super-horizon scales and the transfer of entropy to scalar modes after the horizon crossing. Secondly, we interface our algorithm with Boltzmann integrator codes to compute the subsequent full cosmology, including the cosmic microwave background anisotropies and polarization angular power spectra. Finally, we develop a novel sampling algorithm able to efficiently explore a large volume of the parameter space and identify a sub-region where theoretical predictions agree with observations. In this way, sampling over the initial conditions of the fields and the free parameters of the models, we enable Monte Carlo analysis of multifield scenarios. We test all the features of our approach by analyzing a specific model and deriving constraints on its free parameters. Our methodology provides a robust framework for studying multifield inflation, opening new avenues for future research in the field.

33 pages, 8 figures, V2: edited to match the JCAP published version

References in corpus (50)

• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• Higgs inflation: consistency and generalisations
• Inflationary Cosmology
• SPT-3G: A Next-Generation Cosmic Microwave Background Polarization Experiment on the South Pole Telescope
• Inflation after WMAP3: Confronting the Slow-Roll and Exact Power Spectra with CMB Data
• A new cosmic microwave background constraint to primordial gravitational waves
• Perturbations in generalized multi-field inflation
• Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: implications for the early universe
• Large Field Inflation and Double $\alpha$-Attractors
• Conformal Transformations with Multiple Scalar Fields
• Primordial Bispectrum from Multifield Inflation with Nonminimal Couplings
• Blue Tensor Spectrum from Particle Production during Inflation
• Blue-tilted Tensor Spectrum and Thermal History of the Universe
• A Refined Einstein-Gauss-Bonnet Inflationary Theoretical Framework
• Models of the Primordial Standard Clock
• Standard Clock in Primordial Density Perturbations and Cosmic Microwave Background
• Spectrum of Primordial Gravitational Waves in Modified Gravities: A Short Overview
• Towards early dark energy and $n_s$=1 with Planck, ACT and SPT
• The challenge of ruling out inflation via the primordial graviton background
• Health checkup test of the standard cosmological model in view of recent Cosmic Microwave Background Anisotropies experiments
• How Well Can Future CMB Missions Constrain Cosmic Inflation?
• ${\varphi }^2$ or Not ${\varphi }^2$: Testing the Simplest Inflationary Potential
• Numerical evaluation of the bispectrum in multiple field inflation
• Compatibility of Planck and BICEP2 in the Light of Inflation
• Constraints on Scalar and Tensor spectra from $N_{eff}$
• On the evolution of tachyonic perturbations at super-Hubble scales
• MultiModeCode: An efficient numerical solver for multifield inflation
• Observational Constraints on Theories with a Blue Spectrum of Tensor Modes
• On Perturbation Spectra of N-flation
• Searching for Standard Clocks in the Primordial Universe
• Primordial Perturbations from Multifield Inflation with Nonminimal Couplings
• Stochastic gravitational-wave background in quantum gravity
• Cosmological implications of $n_s\approx 1$ in light of the Hubble tension
• Non-Gaussianities in Multifield Inflation: Superhorizon Evolution, Adiabaticity, and the Fate of fnl
• Gravitational wave consistency relations for multifield inflation
• Reheating, Multifield Inflation and the Fate of the Primordial Observables
• Power Spectra beyond the Slow Roll Approximation in Theories with Non-Canonical Kinetic Terms
• Effects of the Axion Through the Higgs Portal on Primordial Gravitational Waves During the Electroweak Breaking
• Primordial Tensor Perturbation in Double Inflationary Scenario with a Break
• Testing Predictions of the Quantum Landscape Multiverse 2: The Exponential Inflationary Potential
• Testing Predictions of the Quantum Landscape Multiverse 1: The Starobinsky Inflationary Potential
• CMB Anomalies and the Hubble Tension
• Higher-Curvature Corrections and Tensor Modes
• Testing Hybrid Natural Inflation with BICEP2
• Amplification of the Primordial Gravitational Waves Energy Spectrum by a Kinetic Scalar in $F(R)$ Gravity
• Canonical Scalar Field Inflation with String and $R^2$-Corrections
• Testing models of inflation with CMB non-gaussianity
• Effects of a Pre-inflationary de Sitter Bounce on the Primordial Gravitational Waves in $f(R)$ Gravity Theories
• Non-Gaussianity in multi-sound-speed disformally coupled inflation
• Spectra and entropy of multi-field warm inflation

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• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• Inflation, the Hubble Tension and Early Dark Energy: an alternative overview
• Testing the $n_s-H_0$ scaling relation with Planck-independent CMB data
• Testing scale-invariant inflation against cosmological data
• Inflation in non-local hybrid metric-Palatini gravity
• Gravitational waves in a cyclic Universe: resilience through cycles and vacuum state
• Is natural inflation in agreement with CMB data?