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   Craig, Nathaniel; Kumar, Soubhik; McCune, Amara (July 2024, Journal of High Energy Physics)

   Effective field theories (EFTs) of heavy particles coupled to the inflaton are rife with operator redundancies, frequently obscured by sensitivity to both boundary terms and field redefinitions. We initiate a systematic study of these redundancies by establishing a minimal operator basis for an archetypal example, the abelian gauge-Higgs-inflaton EFT. Working up to dimension 9, we show that certain low-dimensional operators are entirely redundant and identify new non-redundant operators with potentially interesting cosmological collider signals. Our methods generalize straightforwardly to other EFTs of heavy particles coupled to the inflaton. 

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   Bojowald, Martin; Ding, Ding (March 2021, Journal of Cosmology and Astroparticle Physics)

   Abstract Canonical methods of quasiclassical dynamics make it possible to go beyond a strict background approximation for cosmological perturbations by including independent fields such as correlation degrees of freedom. New models are introduced and analyzed here for cosmological dynamics in the presence of quantum correlations between background and perturbations, as well as cross-correlations between different modes of a quantum field. Evolution equations for moments of a perturbation state reveal conditions required for inhomogeneity to build up out of an initial vacuum. A crucial role is played by quantum non-locality, formulated by canonical methods as an equivalent local theory with non-classical degrees of freedom given by moments of a quantum state. 

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5. BICEP/Keck and cosmological attractors

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   Kallosh, Renata; Linde, Andrei (December 2021, Journal of Cosmology and Astroparticle Physics)

   Abstract We discuss implications of the latest BICEP/Keck data release for inflationary models, with special emphasis on the cosmological attractors which can describe all presently available inflation-related observational data. These models are compatible with any value of the tensor to scalar ratio r , all the way down to r  = 0. Some of the string theory motivated models of this class predict 10 -3  ≤  r  ≤ 10 -2 . The upper part of this range can be explored by the ongoing BICEP/Keck observations. 

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