Multiple fields in stochastic inflation
Abstract
Stochastic effects in multifield inflationary scenarios are investigated. A hierarchy of diffusion equations is derived, the solutions of which yield moments of the numbers of inflationary efolds. Solving the resulting partial differential equations in multidimensional field space is more challenging than the singlefield case. A few tractable examples are discussed, which show that the number of fields is, in general, a critical parameter. When more than two fields are present for instance, the probability to explore arbitrarily largefield regions of the potential, otherwise inaccessible to singlefield dynamics, becomes nonzero. In some configurations, this gives rise to an infinite mean number of efolds, regardless of the initial conditions. Another difference with respect to singlefield scenarios is that multifield stochastic effects can be large even at subPlanckian energy. This opens interesting new possibilities for probing quantum effects in inflationary dynamics, since the moments of the numbers of efolds can be used to calculate the distribution of primordial density perturbations in the stochasticδN formalism.
 Authors:

 Institute of Cosmology & Gravitation, University of Portsmouth,Dennis Sciama Building, Burnaby Road, Portsmouth, PO1 3FX (United Kingdom)
 School of Astronomy, Institute for Research in Fundamental Sciences (IPM),P.O. Box 193955531, Tehran (Iran, Islamic Republic of)
 Department of Physics, University of Tehran,P.O. Box 14395547, Tehran (Iran, Islamic Republic of)
 Publication Date:
 Sponsoring Org.:
 SCOAP3, CERN, Geneva (Switzerland)
 OSTI Identifier:
 22572104
 Resource Type:
 Journal Article
 Journal Name:
 Journal of Cosmology and Astroparticle Physics
 Additional Journal Information:
 Journal Volume: 2016; Journal Issue: 06; Other Information: PUBLISHERID: JCAP06(2016)043; OAI: oai:repo.scoap3.org:16161; ccby Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 14757516
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COSMOLOGICAL INFLATION; COSMOLOGY; DIFFUSION EQUATIONS; INFLATIONARY UNIVERSE; MANYDIMENSIONAL CALCULATIONS; MATHEMATICAL SOLUTIONS; PERTURBATION THEORY; POTENTIALS; QUANTUM GRAVITY; STOCHASTIC PROCESSES
Citation Formats
Assadullahi, Hooshyar, Firouzjahi, Hassan, Noorbala, Mahdiyar, School of Astronomy, Institute for Research in Fundamental Sciences, Vennin, Vincent, and Wands, David. Multiple fields in stochastic inflation. United States: N. p., 2016.
Web. doi:10.1088/14757516/2016/06/043.
Assadullahi, Hooshyar, Firouzjahi, Hassan, Noorbala, Mahdiyar, School of Astronomy, Institute for Research in Fundamental Sciences, Vennin, Vincent, & Wands, David. Multiple fields in stochastic inflation. United States. doi:10.1088/14757516/2016/06/043.
Assadullahi, Hooshyar, Firouzjahi, Hassan, Noorbala, Mahdiyar, School of Astronomy, Institute for Research in Fundamental Sciences, Vennin, Vincent, and Wands, David. Fri .
"Multiple fields in stochastic inflation". United States. doi:10.1088/14757516/2016/06/043.
@article{osti_22572104,
title = {Multiple fields in stochastic inflation},
author = {Assadullahi, Hooshyar and Firouzjahi, Hassan and Noorbala, Mahdiyar and School of Astronomy, Institute for Research in Fundamental Sciences and Vennin, Vincent and Wands, David},
abstractNote = {Stochastic effects in multifield inflationary scenarios are investigated. A hierarchy of diffusion equations is derived, the solutions of which yield moments of the numbers of inflationary efolds. Solving the resulting partial differential equations in multidimensional field space is more challenging than the singlefield case. A few tractable examples are discussed, which show that the number of fields is, in general, a critical parameter. When more than two fields are present for instance, the probability to explore arbitrarily largefield regions of the potential, otherwise inaccessible to singlefield dynamics, becomes nonzero. In some configurations, this gives rise to an infinite mean number of efolds, regardless of the initial conditions. Another difference with respect to singlefield scenarios is that multifield stochastic effects can be large even at subPlanckian energy. This opens interesting new possibilities for probing quantum effects in inflationary dynamics, since the moments of the numbers of efolds can be used to calculate the distribution of primordial density perturbations in the stochasticδN formalism.},
doi = {10.1088/14757516/2016/06/043},
journal = {Journal of Cosmology and Astroparticle Physics},
issn = {14757516},
number = 06,
volume = 2016,
place = {United States},
year = {2016},
month = {6}
}