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The open effective field theory of inflation

  • Regular Article - Theoretical Physics
  • Open access
  • Published: 31 October 2024
  • Volume 2024, article number 248 (2024)
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Journal of High Energy Physics Aims and scope Submit manuscript
The open effective field theory of inflation
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  • Santiago Agüí Salcedo  ORCID: orcid.org/0009-0003-5390-63671,
  • Thomas Colas  ORCID: orcid.org/0000-0003-3913-80341 &
  • Enrico Pajer  ORCID: orcid.org/0000-0002-7921-44791 

  • 3886 Accesses

  • 40 Citations

  • 18 Altmetric

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A preprint version of the article is available at arXiv.

Abstract

In our quest to understand the generation of cosmological perturbations, we face two serious obstacles: we do not have direct information about the environment experienced by primordial perturbations during inflation, and our observables are practically limited to correlators of massless fields, heavier fields and derivatives decaying exponentially in the number of e-foldings. The flexible and general framework of open systems has been developed precisely to face similar challenges. Building on previous work, we develop a Schwinger-Keldysh path integral description for an open effective field theory of inflation, describing the possibly dissipative and non-unitary evolution of the Goldstone boson of time translations interacting with an unspecified environment, under the key assumption of locality in space and time. Working in the decoupling limit, we study the linear and interacting theory in de Sitter and derive predictions for the power spectrum and bispectrum that depend on a finite number of effective couplings organised in a derivative expansion. The smoking gun of interactions with the environment is an enhanced but finite bispectrum close to the folded kinematical limit. We demonstrate the generality of our approach by matching our open effective theory to an explicit model. Our construction provides a standard model to simultaneously study phenomenological predictions as well as quantum information aspects of the inflationary dynamics.

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Acknowledgments

We thank C. P. Burgess, S. Cespedes, P. Creminelli, J. Grain, R. Holman, G. Kaplanek, S. Melville, A. Nicolis, R. Penco, L. Santoni, B. Salehian, D. Stefanyszyn, V. Vennin and G. Villa for the insightful discussions. T.C. warmly thanks D. Comelli, F. Piazza, A. Tolley and F. Vernizzi for inspiring this research direction. This work has been supported by STFC consolidated grant ST/X001113/1, ST/T000694/1, ST/X000664/1 and EP/V048422/1. S.A.S. is supported by a Harding Distinguished Postgraduate Scholarship.

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  1. Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, U.K.

    Santiago Agüí Salcedo, Thomas Colas & Enrico Pajer

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  1. Santiago Agüí Salcedo
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  2. Thomas Colas
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Correspondence to Thomas Colas.

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Salcedo, S.A., Colas, T. & Pajer, E. The open effective field theory of inflation. J. High Energ. Phys. 2024, 248 (2024). https://doi.org/10.1007/JHEP10(2024)248

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  • Received: 03 May 2024

  • Accepted: 03 October 2024

  • Published: 31 October 2024

  • Version of record: 31 October 2024

  • DOI: https://doi.org/10.1007/JHEP10(2024)248

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Keywords

  • Cosmological models
  • Effective Field Theories
  • de Sitter space
  • Non-Equilibrium Field Theory

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