Cosmological constraints on nonstandard inflationary quantum collapse models

Abstract

We briefly review an important shortcoming -unearthed in previous works-of the standard version of the inflationary model for the emergence of the seeds of cosmic structure. We consider here some consequences emerging from a proposal inspired on ideas of Penrose and Diósi [1-4] about a quantum-gravity induced reduction of the wave function, which has been put forward to address the shortcomings, arguing that its effect on the inflaton field is what can lead to the emergence of the seeds of cosmic structure [5].The proposal leads to a deviation of the primordial spectrum from the scale-invariant Harrison-Zel'dovich one, and consequently, to a different CMB power spectrum. We perform statistical analyses to test two quantum collapse schemes with recent data from the CMB, including the 7-yr release of WMAP and the matter power spectrum measured using LRGs by the Sloan Digital Sky Survey. Results from the statistical analyses indicate that several collapse models are compatible with CMB and LRG data, and establish constraints on the free parameters of the models. The data put no restriction on the timescale for the collapse of the scalar field modes.PACS numbers: 98.80Cq,98.70Vc

Quantum origin of the primordial fluctuation spectrum and its statistics

“…In fact, analyses of this issue have been carried out in Refs. [8,9], confirming these expectations. These have been used to set the first bounds emerging from the CMB observational data on these kinds of theories.…”

“…In the context of inflationary cosmology, the works (Refs. [4,[8][9][10]14]) are an example in which the issues are faced directly. Those works represent the position we favor, and which is inspired, in part, by the arguments made in Refs.…”

Inflation including collapse of the wave function: the quasi-de Sitter case

“…In previous papers [3,7] the collapse proposal was developed using an "almost" exact de Sitter expansion factor dur-ing the inflationary period [i.e., it was assumed that the (cosmic) time derivative of the Hubble factorḢ was exactly a constant]. In consequence, the primordial power spectrum, modified by the collapse hypothesis, resulted in a form P(k) = A s C(k), that is, a power spectrum with scalar spectral index n s = 1, and with C(k) a function representing the modification induced by the collapse hypothesis; in particular, the function C(k) depends on the time of collapse of each mode of the inflaton field.…”

“…In consequence, the primordial power spectrum, modified by the collapse hypothesis, resulted in a form P(k) = A s C(k), that is, a power spectrum with scalar spectral index n s = 1, and with C(k) a function representing the modification induced by the collapse hypothesis; in particular, the function C(k) depends on the time of collapse of each mode of the inflaton field. Furthermore, the temperature and polarization power spectrum of the CMB were also modified; therefore, the proposals' predictions could be tested against current observational data [7]. In such a way, it was possible to recover an exact scale-invariant power spectrum for some values of the collapse parameters that are related to the time of collapse of each mode of the inflaton field.…”

“…In fact, a simple calculation of the χ 2 value for the models presented in Ref. [7], where an almost exact de Sitter background was considered using the CMB temperature data released by Planck [28], the CMB polarization data reported by WMAP [29], the CMB temperature data for high values of l reported by the Atacama Cosmology Project (ACT) [30] and the South Pole Telescope (SPT) [31], yields a value that is several orders of magnitude above the expected reasonable value. The difference between the analysis performed in the former paper and this simple calculation is that the data obtained by the Planck, ACT, and SPT collaborations are much more accurate for small angular scales than the 7-years release of WMAP.…”