232 research outputs found
Dark energy and formation of classical scalar fields
We present a quintessence model for the dark energy in which the quintessence
scalar field is produced by the decay of a super heavy dark matter and
gradually condensate to a classical scalar field. This model can explain both
the smallness and the latest observations by WMAP for the equation of state of
the dark energy which has . We review both classical and field
theoretical treatment of this model and briefly explain the most important
parameters for obtaining the observed characteristic of the dark energy.Comment: 7 pages,2 figures. Proceedings of Einstein 2005 Conferenc
Cosmological Condensation of Scalar Fields -- Making a dark energy
Our Universe is ruled by quantum mechanics and its extension Quantum Field
Theory (QFT). However, the explanations for a number of cosmological phenomena
such as inflation, dark energy, symmetry breakings, and phase transitions need
the presence of classical scalar fields. Although the process of condensation
of scalar fields in the lab is fairly well understood, the extension of results
to a cosmological context is not trivial. Here we investigate the formation of
a condensate - a classical scalar field - after reheating of the Universe. We
assume a light quantum scalar field produced by the decay of a heavy particle,
which for simplicity is assumed to be another scalar. We show that during
radiation domination epoch under certain conditions, the decay of the heavy
particle alone is sufficient for the production of a condensate. This process
is very similar to preheating - the exponential particle production at the end
of inflation. During matter domination epoch when the expansion of the Universe
is faster, the decay alone can not keep the growing trend of the field and the
amplitude of the condensate decreases rapidly, unless there is a self
interaction. This issue is particularly important for dark energy. We show that
quantum corrections of the self-interaction play a crucial role in this
process. Notably, they induce an effective action which includes inverse
power-law terms, and therefore can lead to a tracking behaviour even when the
classical self-interaction is a simple power-law of order 3 or 4. This removes
the necessity of having nonrenormalisable terms in the Lagrangian. If dark
energy is the condensate of a quantum scalar field, these results show that its
presence is deeply related to the action of quantum physics at largest
observable scales.Comment: 36 pages, 1 figur
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