Self-resonance after inflation: Oscillons, transients, and radiation domination

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dc.citation.articleNumber023533
dc.citation.issueNumber2
dc.citation.journalTitlePhysical Review D
dc.citation.volumeNumber97
dc.contributor.authorLozanov, Kaloian D.
dc.contributor.authorAmin, Mustafa A.
dc.date.accessioned2018-02-26T17:22:12Z
dc.date.available2018-02-26T17:22:12Z
dc.date.issued2018
dc.description.abstractHomogeneous oscillations of the inflaton after inflation can be unstable to small spatial perturbations even without coupling to other fields. We show that for inflaton potentials ∝|ϕ|2n near |ϕ|=0 and flatter beyond some |ϕ|=M, the inflaton condensate oscillations can lead to self-resonance, followed by its complete fragmentation. We find that for nonquadratic minima (n>1), shortly after backreaction, the equation of state parameter, w→1/3. If M≪mPl, radiation domination is established within less than an e-fold of expansion after the end of inflation. In this case self-resonance is efficient and the condensate fragments into transient, localised spherical objects which are unstable and decay, leaving behind them a virialized field with mean kinetic and gradient energies much greater than the potential energy. This end-state yields w=1/3. When M∼mPl we observe slow and steady, self-resonance that can last many e-folds before backreaction eventually shuts it off, followed by fragmentation and w→1/3. We provide analytical estimates for the duration to w→1/3 after inflation, which can be used as an upper bound (under certain assumptions) on the duration of the transition between the inflationary and the radiation dominated states of expansion. This upper bound can reduce uncertainties in CMB observables such as the spectral tilt ns, and the tensor-to-scalar ratio r. For quadratic minima (n=1), w→0 regardless of the value of M. This is because when M≪mPl, long-lived oscillons form within an e-fold after inflation, and collectively behave as pressureless dust thereafter. For M∼mPl, the self-resonance is inefficient and the condensate remains intact (ignoring long-term gravitational clustering) and keeps oscillating about the quadratic minimum, again implying w=0.
dc.identifier.citationLozanov, Kaloian D. and Amin, Mustafa A.. "Self-resonance after inflation: Oscillons, transients, and radiation domination." <i>Physical Review D,</i> 97, no. 2 (2018) American Physical Society: https://doi.org/10.1103/PhysRevD.97.023533.
dc.identifier.digitalSelf-resonance-after-inflation
dc.identifier.doihttps://doi.org/10.1103/PhysRevD.97.023533
dc.identifier.urihttps://hdl.handle.net/1911/99293
dc.language.isoeng
dc.publisherAmerican Physical Society
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
dc.titleSelf-resonance after inflation: Oscillons, transients, and radiation domination
dc.typeJournal article
dc.type.dcmiText
dc.type.publicationpublisher version
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