Features of heavy physics in the CMB power spectrum

By A. Ach'ucarro, Jinn-Ouk Gong, S. Hardeman, G. Palma, S. Patil. 2010

414 citations recorded by the source corpus.

The computation of the primordial power spectrum in multi-field inflation models requires us to correctly account for all relevant interactions between adiabatic and non-adiabatic modes around and after horizon crossing. One specific complication arises from derivative interactions induced by the curvilinear trajectory of the inflaton in a multi-dimensional field space. In this work we compute the power spectrum in general multi-field models and show that certain inflaton trajectories may lead to observationally significant imprints of `heavy' physics in the primordial power spectrum if the inflaton trajectory turns, that is, traverses a bend, sufficiently fast (without interrupting slow roll), even in cases where the modes normal to the trajectory have masses approaching the cutoff of our theory. We emphasize that turning is defined with respect to the geodesics of the sigma model metric, irrespective of whether this is canonical or non-trivial. The imprints generically take the form of damped superimposed oscillations on the power spectrum. In the particular case of two-field models, if one of the fields is sufficiently massive compared to the scale of inflation, we are able to compute an effective low energy theory for the adiabatic mode encapsulating certain relevant operators of the full multi-field dynamics. As expected, a particular characteristic of this effective theory is a modified speed of sound for the adiabatic mode which is a functional of the background inflaton trajectory and the turns traversed during inflation. Hence in addition, we expect non-Gaussian signatures directly related to the features imprinted in the power spectrum.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/433ea5bccde9fb9e1c1ce25502433dee1c069b2b

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Citations in the corpus

Effective field theory approach to quasi-single field inflation and effects of heavy fields (2012, background): “Therefore, the power spectrum is not affected by heavy particles unless the mixing couplings are comparable to the mass of heavy particles [19–28].”
Inflation, Cosmic Perturbations and Non-Gaussianities (2013, background): “Here we review a sharp turning of inflationary trajectory [216–224].”
Mass hierarchies and non-decoupling in multi-scalar field dynamics (2010, methodology): “For this reason, in the present note we study the basic features of the effects of the heavy-light field interactions during turns of the scalar field trajectory in a Minkowski background, and leave the study of inflationary de Sitter case for a separate paper [15].”
Effective theories of single field inflation when heavy fields matter (2012, background): “J H E P 0 5 ( 2 0 1 2 ) 0 6 6 that one might have previously neglected to become transiently strongly coupled, consistent with perturbative unitarity and the consistency of our derivative expansion, in a way that can imprint features on the primordial power spectrum [10] due to the induced variation”
Planck 2015 results. XVII. Constraints on primordial non-Gaussianity (2015, neutral): “However, in multifield models residual oscillations after corner-turning can also lead to logspaced oscillations, just as in the resonance models (Chen 2011; Achúcarro et al. 2011; Battefeld et al. 2013; Chen et al. 2015).”
Planck 2018 results. IX. Constraints on primordial non-Gaussianity (2019, background): “Finally, we note that there are multifield models in which sharp corner-turning can result in residual oscillations with logarithmic spacing, thus mimicking resonance models (Achúcarro et al. 2011; Battefeld et al. 2013).”
Exploring cosmic origins with CORE: Inflation (2016, background): “Most interesting for us are features that originated during inflation, as these can probe energy scales well beyond H [142, 143] and may reveal new mass scales and interactions difficult to probe in any other way.”
Signature of supersymmetry from the early universe (2011, methodology): “We presented a specific two-field theory (see also [42–44]) that allows for large non-Gaussianities at Hubble without strong coupling above Hubble.”
Quasi-single field inflation with large mass (2012, background): “This verifies the result from the semi-classical approximation in the large M limit [16, 8].”