MG13 - Talk detail

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 Participant

Institution

Session

Accepted

Yes

Order

Time

Talk

Title

Abstract

FRW model with nonminimally coupled scalar field is considered. It is classically known that for a specific form of the coupling the scalar field produces inflation: of particular interest these days is the observation that this model allows for Higgs-driven inflation, avoiding introduction of new particle physics. We consider the LQC corrections to the equations of motion in the framework of "effective dynamics", finding the dynamics of the model at early times. It is found that the initial singularity is replaced by a peculiar "mexican hat" bounce: the universe collapses, at Planck scales it undergoes two consecutive bounces between which it rapidly expands and recollaplses, and finally it reaches inflation. For physical values of the coupling constant the count of e-foldings and the computation of cosmological parameters show that the model is in agreement with observations - providing a nonsingular cosmology where inflation can be generated by standard model fields (such as the Higgs).

Session

Accepted

Yes

Order

Time

Talk

Title

Abstract

We develop the quantum theory of a scalar field on LQC Bianchi I geometry. In particular, we focus on single modes of the field: the evolution equation is derived from the quantum scalar constraint, and it is shown that the same equation can be obtained from QFT on an "classical" effective geometry. We investigate the dependence of this effective spacetime on the wave-vector of the mode (which could in principle generate a deformation in local Lorentz-symmetry), focusing our attention on the dispersion relation. We prove that at first order no Lorentz-violation is present - despite the effective metric being different than the classical Bianchi I one. A preliminary analysis of the correction due to inclusion of backreaction is briefly discussed in the context of Born-Oppenheimer approximation.

Session

Accepted

Yes

Order

Time

Talk

Title

Abstract

We conduct a LQC-quantization of the FRW cosmological model with nonminimally coupled scalar field. (This model is interesting from the classical point of view because it allows heavy fields (such as the Higgs) to produce inflation.) Making use of a canonical transformation (between Jordan variables and Einstein variables), we recast the theory in a minimally coupled one, for which standard LQC techniques can be applied to find the physical Hilbert space and the dynamics. Though the analysis of the genuine quantum system can be performed, we focus on the semiclassical sector - obtaining a "classical" effective Hamiltonian. At this level, we can transform back to the Jordan frame, and study the dynamics. It turns out that the initial singularity is replaced by a "mexican hat"-shaped bounce, joining the contracting and expanding branches.

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