The effective field theory of multifield inflation

By L. Senatore, M. Zaldarriaga. Journal of High Energy Physics, 2010

247 citations recorded by the source corpus.

We generalize the Effective Field Theory of Inflation to include additional light scalar degrees of freedom that are in their vacuum at the time the modes of interest are crossing the horizon. In order to make the scalars light in a natural way we consider the case where they are the Goldstone bosons of a global symmetry group or are partially protected by an approximate supersymmetry. We write the most general Lagrangian that couples the scalar mode associated to the breaking of time translation during inflation to the additional light scalar fields. This Lagrangian is constrained by diffeomorphism invariance and the additional symmetries that keep the new scalars light. This Lagrangian describes the fluctuations around the time of horizon crossing and it is supplemented with a general parameterization describing how the additional fluctuating fields can affect cosmological perturbations. We find that multifield inflation can reproduce the non-Gaussianities that can be generated in single field inflation but can also give rise to new kinds of non-Gaussianities. We find several new three-point function shapes. We show that in multifield inflation it is possible to naturally suppress the three-point function making the four-point function the leading source of detectable non-Gaussianities. We find that under certain circumstances, i.e. if specific shapes of non-Gaussianities are detected in the data, one could distinguish between single and multifield inflation and sometimes even among the various mechanisms that kept the additional fields light.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/27797e5e16d62e3d755630a8003f0587b98090ce

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In Astronomy and Astrophysics

1. D. Baumann
2. L. Senatore
3. M. Zaldarriaga
4. Yi Wang
5. Xingang Chen
6. D. Green
7. E. Pajer
8. F. Vernizzi

Citations in the corpus

• The effective field theory of cosmological large scale structures (2012, background): “These observations contain huge amount of information on Dark Energy and on Inflation, through for example the non-Gaussianity of the primordial perturbations.”
• Inflation, Cosmic Perturbations and Non-Gaussianities (2013, methodology): “Instead, the EFT approach can be used widely in cosmology, including applications in multi-field inflation [158], quasi-single field inflation [159, 160] and large scale structures [161].”
• Effective field theory of dark energy: A review (2019, background): “In this regard, an interesting field of investigation could be to generalize the EFT construction to include additional DoFs whose dynamics is relevant at late time following the example of the EFT of multi-field Inflation [327].”
• The (not so) squeezed limit of the primordial 3-point function (2011, background): “This can be done remaining in the effective theory approach following [32].”
• Bias in the effective field theory of large scale structures (2014, background): “However, once going to comoving coordinates that move with a region, it is only points a distance of order 1/kM (3)People familiar with the Effective Field Theory of Inflation [14, 15] might remember that g∂μ is invariant, not ∂/∂t.”
• Symmetries and loops in inflation (2012, background): “An effective theory for the Goldstone mode π has been constructed in [9, 10] (for related work see [17–27]).”
• Effective field theory approach to quasi-single field inflation and effects of heavy fields (2012, background): “6 Then, let us For example, we do not require the shift symmetry of σ, σ → σ+ constant, which is assumed in multifield inflation [39].”
• Oscillations in the stochastic gravitational wave background from sharp features and particle production during inflation (2020, background): “[87, 88] in a multifield context), each type of perturbations can propagate with reduced sound speeds, and it would be interesting to generalise our findings to such setups.”
• On graviton non-gaussianities during inflation (2011, methodology): “Once we are away from the de Sitter approximation, one can still study the higher derivative corrections in a systematic fashion as explained in [3, 6, 14].”
• Non-Gaussianity as a particle detector (2016, background): “For constructions of the EFT of inflation with extra scalar fields, see [8, 11].”
• The cosmological bootstrap: inflationary correlators from symmetries and singularities (2018, unknown): “conformal symmetry more strongly, as in models with a reduced sound speed of the inflationary fluctuations [59, 115–117], or strongly coupled fluctuations, as in some holographic models of dS/CFT [118].”
• The effective field theory of dark energy (2012, background): “See also [20,21] for later generalizations to multi-field inflation and dissipative effects in inflation.”