Stochastic inflation in a simple two-field model

Journal Article · Sun Sep 15 00:00:00 EDT 1991 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.44.1670· OSTI ID:5133670

Mollerach, S ^[1]; Matarrese, S ^[2]; Ortolan, A ^[3]; Lucchin, F ^[4]

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1. Scuola Internazionale Superiore di Studi Avanzati, Strada Costiera 11, 34014 Trieste (Italy)
2. Dipartimento di Fisica Galileo Galilei'' Universita di Padova, via Marzolo 8, 35131 Padova (Italy)
3. Dipartimento di Fisica Universita di Ferrara and Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, via Paradiso 12, 44100 Ferrara (Italy)
4. Dipartimento di Astronomia Universita di Padova, vicolo dell'Osservatorio 5, 35122 Padova (Italy)

The dynamics of a nondominating scalar field during inflation is considered in the framework of the stochastic approach where its motion and that of the inflaton are described by two coupled Langevin equations. Curvature perturbations induced by the inflaton make the problem that of a Brownian motion in a random medium. The associated Fokker-Planck equation is solved for a free massless field in a power-law inflation driven by an inflaton with an exponential potential: this simple model could describe the dynamics of the axion, or any other pseudoGoldstone boson, during inflation. In spite of being free, the field shows a highly non-Gaussian behavior on scales much larger than the present horizon; on observable scales it gives rise to isocurvature perturbations which are both essentially Gaussian and scale-free.

• OSTI ID: 5133670
• Journal Information: Physical Review, D (Particles Fields); (United States), Vol. 44:6; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
INFLATIONARY UNIVERSE
STOCHASTIC PROCESSES
AXIONS
BROWNIAN MOVEMENT
FOKKER-PLANCK EQUATION
GOLDSTONE BOSONS
LANGEVIN EQUATION
NONLUMINOUS MATTER
PERTURBATION THEORY
SCALAR FIELDS
BOSONS
COSMOLOGICAL MODELS
DIFFERENTIAL EQUATIONS
ELEMENTARY PARTICLES
EQUATIONS
MATHEMATICAL MODELS
MATTER
PARTIAL DIFFERENTIAL EQUATIONS
POSTULATED PARTICLES
640106* - Astrophysics & Cosmology- Cosmology
657002 - Theoretical & Mathematical Physics- Classical & Quantum Mechanics