Nonsingular cosmology with a scale-invariant spectrum of cosmological perturbations from Lee-Wick theory

By Yi-Fu Cai, Taotao Qiu, Robert Brandenberger, Xinmin Zhang. 2008

212 citations recorded by the source corpus.

We study the cosmology of a Lee-Wick type scalar field theory. First, we consider homogeneous and isotropic background solutions and find that they are nonsingular, leading to cosmological bounces. Next, we analyze the spectrum of cosmological perturbations which result from this model. Unless either the potential of the Lee-Wick theory or the initial conditions are finely tuned, it is impossible to obtain background solutions which have a sufficiently long period of inflation after the bounce. More interestingly, however, we find that in the generic noninflationary bouncing cosmology, perturbations created from quantum vacuum fluctuations in the contracting phase have the correct form to lead to a scale-invariant spectrum of metric inhomogeneities in the expanding phase. Since the background is nonsingular, the evolution of the fluctuations is defined unambiguously through the bounce. We also analyze the evolution of fluctuations which emerge from thermal initial conditions in the contracting phase. The spectrum of gravitational waves stemming from quantum vacuum fluctuations in the contracting phase is also scale-invariant, and the tensor to scalar ratio is not suppressed.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/ed22ab97b8c098a96f83ed4f74154c22f508dfd6

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

The Matter Bounce Alternative to Inflationary Cosmology (2012, methodology): “In models with only adiabatic fluctuations, the bottom line of many detailed studies is that on length scales which are longer than the time duration of the bounce the spectral index of the power spectrum of v is not changed [21, 34–38] (however, as stressed in [39], this is not a completely general”
Exploring bouncing cosmologies with cosmological surveys (2014, background): “They appear in many theoretical settings where either the gravitational sector is modified as in Hor̆ava gravity [56–58], non-relativistic gravitational action[59], torsion gravity [60, 61], Lagrange-multiplier gravity [62, 63], nonlinear massive gravity [64] and non-local gravity [65], or by making”
The matter bounce scenario in loop quantum cosmology (2012, unknown): “Two matter bounce cosmologies that give similar predictions are (i) with a Lee-Wick type scalar field that causes a bounce [19] (the case where the LeeWick scalar is non-minimally coupled to gravity is studied in [20]), and (ii) in the setting of the f(T ) generalization of teleparallel gravity [21]”
Non-singular cosmology in a model of non-relativistic gravity (2009, background): “One model of bouncing cosmology with a matter-dominated contraction was found to be able to provide a scale-invariant spectrum [36–40] and sizable non-Gaussianities [41, 42], which may be responsible for the current cosmological observations.”
Bouncing Cosmologies: Progress and Problems (2016, methodology): “[78] Y.”
Matter bounce in Horava-Lifshitz cosmology (2009, background): “It has been shown [17, 18, 19, 20] that, provided the duration of the bounce phase is short compared to the wavelength of the fluctuations being considered, then the spectrum of curvature fluctuations is not changed during the bounce.”