We extend the warm inflationary scenario to the case of the noncanonical
scalar fields. The equation of motion and the other basic equations of this new
scenario are obtained. The Hubble damped term is enhanced in noncanonical
inflation. A linear stability analysis is performed to give the proper
slow-roll conditions in warm noncanonical inflation. We study the density
fluctuations in the new picture and obtain an approximate analytic expression
of the power spectrum. The energy scale at the horizon crossing is depressed by
both noncanonical effect and thermal effect, and so is the tensor-to-scalar
ratio. Besides the synergy, the noncanonical effect and the thermal effect are
competing in the case of the warm noncanonical inflation.Comment: 7 pages, 0 figures, accepted by Physical Review
We study the two-field warm inflation models with a double quadratic potential and a linear temperature dependent dissipative coefficient. We derived the evolution equation of all kinds of perturbations without assuming slow-roll approximation, and obtained the curvature power spectrum at the end of inflation with a fully numerical method. Then we compute the scalar spectral index ns, tensor-to-scalar ratio r for several representative potentials, and compare our results with observational data. At last, we use Planck data to constrain the parameters in our models. This work is a natural extension of single-field warm inflation, and the aim of this work is to present some features of multi-field warm inflation using a simple two-field model.
Recent investigation shows that the big bang is replaced by a big bounce by evolving the semiclassical states backwards. And the effective dynamics predicted by the effective Hamiltonian is shown to match very well with the evolution of the semiclassical state [9,10]. In the * Electronic address: jimhard@163.com †
We investigate the warm inflation condition in loop quantum cosmology. In our consideration, the system is described by a tachyon field interacted with radiation. The exponential potential function, V (φ) = V0e −αφ , with the same order parameters V0 and α, is taken as an example of this tachyon warm inflation model. We find that, for the strong dissipative regime, the total number of e-folds is less than the one in the classical scenario, and for the weak dissipative regime, the beginning time of the warm inflation will be later than the tachyon (cool) inflation.PACS numbers: 98.80.Cq
Anomaly-free perturbations of loop quantum cosmology reveal a deformed space-time structure, in which the signature changes when the energy density is ρ = ρ c /2. Furthermore, in loop quantum cosmology, one can obtain an effective causal structure only for a low density region (ρ ≤ ρ c /2), which gives a natural initial condition to consider the horizon problem. Choosing the initial value at ρ(0) = ρ c /2 in this paper, we investigate the horizon problem and the probability of inflation in the framework of loop quantum cosmology. Two models are considered: the quadratic inflation and the natural inflation. We use the Liouville measure to calculate the probability of inflation which solves the horizon problem, and find that, for the quadratic inflation model, the probability is very close to unity, while for the natural inflation model, the probability is about 35%.
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