Quantum primordial standard clocks

Abstract

In this paper, we point out and study a generic type of signals existing in the primordial universe models, which can be used to model-independently distinguish the inflation scenario from alternatives. These signals are generated by massive fields that function as standard clocks. The role of massive fields as standard clocks has been realized in previous works. Although the existence of such massive fields is generic, the previous realizations require sharp features to classically excite the oscillations of the massive clock fields. Here, we point out that the quantum fluctuations of massive fields can actually serve the same purpose as the standard clocks. We show that they are also able to directly record the defining property of the scenario type, namely, the scale factor of the primordial universe as a function of time a(t), but through shape-dependent oscillatory features in non-Gaussianities. Since quantum fluctuating massive fields exist in any realistic primordial universe models, these quantum primordial standard clock signals are present in any inflation models, and should exist quite generally in alternative-to-inflation scenarios as well. However, the amplitude of such signals is very model-dependent.

Non-Gaussianity as a particle detector

“…At the same time, there 15 The displayed µs scalings are the asymptotic behaviors for large µs. There is also a polynomial dependence in µs for the non-analytic part which competes with the exponential suppression for intermediate values of µs.…”

Prospects for cosmological collider physics

“…1. Except for the squeezed limit shape, there is no full analytic expression available, but partial results including the full shape that contains the clock signal have been been provided [20]. Ref.…”

“…Ref. [20] also showed how to efficiently evaluate the necessary integrals using Wick rotations. We review the derivation of the shape from the in-in formalism and details of the numerical evaluation of the integrals in Appendix A.…”

“…The possible amplitudes of these bispectra span a wide range of values, and strongly depend on the nature of couplings in the model [2,3,20,29]. It is the purpose of this paper to investigate what sizes of the bispectrum may be measurable and the detectability of heavy particles in the futurist 21-cm experiments.…”

Constraining chameleon field driven warm inflation with Planck 2018 data

“…Following [16], and from the observational point of view, we can classify the huge number of different models of inflation into three main categories, with their related sub-categories. These are the single-field inflation [61][62][63][64][65][66][67][68][69][70][71][72][73][74], the multiple-field inflation [75][76][77][78][79][80][81][82] and those models in which the fluid is not described by scalar fields [83][84][85][86][87].…”