Abstract
We argue that the Starobinsky model of inflation, realised via an R2 term in the Lagrangian, can originate from quantum effects due to a tower of light species. By means of two separate arguments, we show how this implies that the scale of the R2 term must be of order of the species scale Λs, namely the energy at which gravity becomes strongly coupled. We discuss the implications and challenges of this scenario for inflation, inflationary reheating, and string theory embeddings. In this context, we collect strong evidence to conclude that Starobinsky inflation lies in the Swampland.
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Acknowledgments
We would like to thank Ed Copeland, Niccolò Cribiori, Anamaria Hell, Renata Kallosh, Sergey Ketov, Osmin Lacombe, Andrei Linde, Swagat Mishra, and Tony Padilla for helpful comments and discussions. The work of D.L. is supported by the Origins Excellence Cluster and by the German-Israel-Project (DIP) on Holography and the Swampland. B.M. is supported by a UK Science and Technology Facilities Council studentship.
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Lüst, D., Masias, J., Muntz, B. et al. Starobinsky inflation in the swampland. J. High Energ. Phys. 2024, 186 (2024). https://doi.org/10.1007/JHEP07(2024)186
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DOI: https://doi.org/10.1007/JHEP07(2024)186