Primordial gravitational waves from excited states
Author
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Fumagalli, Jacopo
Author
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Palma Quilodrán, Gonzalo
Author
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Renaux-Petel, Sébastien
Author
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Sypsas, Spyros
Author
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Witkowskia, Lukas T.
Author
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Zenteno, Cristóbal
Admission date
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2022-07-15T14:32:11Z
Available date
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2022-07-15T14:32:11Z
Publication date
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2022
Cita de ítem
dc.identifier.citation
Journal of High Energy Physics (2022) Article Number196
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Identifier
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10.1007/JHEP03(2022)196
Identifier
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https://repositorio.uchile.cl/handle/2250/186757
Abstract
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We show that a scalar excited state with large occupation numbers during inflation leads to an enhancement of tensor modes and a characteristic pattern of order-one oscillations in the associated stochastic gravitational wave background (SGWB) sourced during inflation. An effective excited state, i.e. a departure from the Bunch-Davies vacuum, can emerge dynamically as the result of a transient non-adiabatic evolution, e.g. a sharp feature along the inflationary history. We provide an explicit example in a multifield context where the sharp feature triggering the excited state is identified with a strong turn in the inflationary trajectory. En passant, we derive a universal expression for the tensor power spectrum sourced at second order by an arbitrary number of scalar degrees of freedom during inflation, crucially taking into account the nontrivial structure of the Hilbert space in multifield setups. The SGWB sourced during inflation can overcome the standard scalar-induced SGWB sourced at horizon re-entry of the fluctuations after inflation, while being less constrained by perturbativity and backreaction bounds. In addition, one may entertain the possibility of detecting both since they peak at different frequencies exhibiting oscillations with distinct periods.
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Patrocinador
dc.description.sponsorship
European Research Council (ERC) 758792
Contrato de Atraccion de Talento (Modalidad 1) de la Comunidad de Madrid (Spain) 2017-T1/TIC-5520
IFT Centro de Excelencia Severo Ochoa Grant SEV-2
Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)
CONICYT FONDECYT 1210876
"CUniverse" research promotion project by Chulalongkorn University (grant reference CUAASC)
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Lenguage
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en
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Publisher
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Springer
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Type of license
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Attribution-NonCommercial-NoDerivs 3.0 United States