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Author Ferreiro, A.; Torrenti, F. url  doi
openurl 
  Title Ultraviolet-regularized power spectrum without infrared distortions in cosmological spacetimes Type Journal Article
  Year 2023 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 840 Issue Pages 137868 - 6pp  
  Keywords  
  Abstract We reexamine the regularization of the two-point function of a scalar field in a Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime. Adiabatic regularization provides a set of subtraction terms in momentum space that successfully remove its ultraviolet divergences at coincident points, but can significantly distort the power spectrum at infrared scales, especially for light fields. In this work we propose, by using the intrinsic ambiguities of the renormalization program, a new set of subtraction terms that minimize the distortions for scales k less than or similar to M, with M an arbitrary mass scale. Our method is consistent with local covariance and equivalent to general regularization methods in curved spacetime. We apply our results to the regularization of the power spectrum in de Sitter space: while the adiabatic scheme yields exactly Delta((reg))(phi) = 0 for a massless field, our proposed prescription recovers the standard scale-invariant result Delta((reg))(phi) similar or equal to H-2/(4 pi(2)) at super-horizon scales.  
  Address [Ferreiro, Antonio] Dublin City Univ, Ctr Astrophys & Relat, Sch Math Sci, Dublin 9, Ireland, Email: antonio.ferreiro@dcu.ie;  
  Corporate Author Thesis  
  Publisher Elsevier Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title (up) Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000968486900001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5514  
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Author Ferreiro, A.; Monin, S.; Torrenti, F. url  doi
openurl 
  Title Physical scale adiabatic regularization in cosmological spacetimes Type Journal Article
  Year 2024 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 109 Issue 4 Pages 045015 - 16pp  
  Keywords  
  Abstract We develop a new regularization method for the stress -energy tensor and the two -point function of free quantum scalar fields propagating in cosmological spacetimes. We proceed by extending the adiabatic regularization scheme with the introduction of two additional mass scales. By setting them to the order of the physical scale of the studied scenario, we obtain ultraviolet -regularized quantities that do not distort the power spectra amplitude at the infrared scales amplified by the expansion of the Universe. This is not ensured by the standard adiabatic approach. We also show how our proposed subtraction terms can be interpreted as a renormalization of coupling constants in the Einstein equations. We finally illustrate our proposed regularization method in two scenarios of cosmological interest: de Sitter inflation and geometric reheating.  
  Address [Ferreiro, Antonio] Univ Utrecht, Freudenthal Inst, NL-3584CC Utrecht, Netherlands, Email: antonio.ferreiro@ru.nl;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title (up) Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001180335500003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6015  
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