Abstract
We look for oscillating signals in the primordial bispectrum from new physics heavy particles which are visibly large for next generation large scale structures (LSS) survey. We show that in ordinary inflation scenarios where a slow-rolling inflaton generates density fluctuations and with no breaking of scale invariance or spacetime symmetry, there exist no naturally large signals unless the rolling inflaton generates a parity-odd chemical potential for the heavy particles. We estimate the accessibility of this signal through observations. While current CMB data are already sensitive in the most optimistic scenario, future probes, including LSS survey and 21 cm observation, can cover interesting regions of the model space.
Highlights
Future probes of the 3-point correlation, commonly known as the non-Gaussianity (NG)
We look for oscillating signals in the primordial bispectrum from new physics heavy particles which are visibly large for generation large scale structures (LSS) survey
The difficulty stems from the fact that a large signal would need large coupling, which would in turn introduce large mass corrections to the matter field due to its coupling with the inflaton background (φ0 or φ0)
Summary
We look for inflaton-matter couplings that can generate large cosmological collider signals. We require that there should not be large cancellation between different terms in the Lagrangian to the mass of the matter particle These are not requirements based on consistency of the theory, but on naturalness considerations. It is interesting to observe that the scenario of chemical potential can still lead to naturally large signal even we exclude loop-level fine tuning, since this mechanism works only for fermions or gauge bosons, whose mass can be made stable against loop corrections. We do not choose this framework because the naturalness consideration is essentially about the underlying model, which the EFT framework does not capture It obscures the derivative expansion in terms of φ, which makes the relative importance of operators less transparent
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