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Arjun Berera 《Pramana》2009,72(1):169-182
This talk presents some recent work that has been done in inflationary cosmology. First a brief review is given of the inflation
scenario and its basic models. After that, one of the main problems in developing inflationary models has been the requirement
of a very flat inflation potential. In solving this problem, supersymmetry has played a major role, and the reasons will be
discussed and a specific example of the SUSY hybrid model will be examined. Some problems introduced by SUSY such as the η and gravitino problems will then be discussed. Then in a different direction, the quintessential inflation model will be
examined as a proposal where a single scalar field plays the role of both the inflaton at early time and the dark energy field
later. The final topic covered is developments in understanding dissipation and particle production processes during the inflationary
phase.
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《Physics letters. [Part B]》1988,214(4):508-514
The generation of initial perturbations in inflationary cosmological models in the presence of fluctuations of several scalar fields is considered. It is shown that there is a possibility to build the model-dependent spectrum both of adiabatic (inflation) and isothermal (isoinflaton) density perturbations, containing a separate maximum, large-scale power or increasing at large (at small) wavelengths, which are of essential interest for the theory of the large-scale structure of the Universe. 相似文献
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We consider a 5D Kaluza-Klein type cosmological model with the fifth coordinate being a generalization of the invariant historical time of the covariant theory of Horwitz and Piron. We distinguish between vacuum-, off-shell matter-, and on-shell matter-dominated eras as the solutions of the corresponding 5D gravitational field equations, and build an inflationary scenario according to which passage from the off-shell matter-dominated era to the on-shell one occurs, probably as a phase transition. We study the effect of this phase transition on the expansion rate in both cases of localO(4,1) andO(3,2) invariance of the extended (x
µ,) manifold and show that it does not change in either case. The expansion of the model we consider is not adiabatic; the thermodynamic entropy is a growing function of cosmic time for the closed universe, and can be a growing function of historical time for the open and the flat universe. A complete solution of the 5D gravitational field equations is obtained for the on-shell matter-dominated universe. The open and the closed universe are shown to tend asymptotically to the standard 4D cosmological models, in contrast to the flat universe which does not have the corresponding limit. Finally, possible cosmological implications are briefly discussed. 相似文献
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We study a closed model of the universe filled with viscous fluid and quintessence matter components in a Brans-Dicke type cosmological model. The dynamical equations imply that the universe may look like an accelerated flat Friedmann-Robertson-Walker universe at low redshift. We consider here dissipative processes which follow a causal thermodynamics. The theory is applied to viscous fluid inflation, where accepted values for the total entropy in the observable universe are obtained. 相似文献
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We revisit the gravitational production of massive Dirac fermions in inflationary cosmology with a focus on clarifying the analytic computation of the particle number density in both the large and the small mass regimes. For the case in which the masses of the gravitationally produced fermions are small compared to the Hubble expansion rate at the end of inflation, we obtain a universal result for the number density that is nearly independent of the details of the inflationary model. The result is identical to the case of conformally coupled scalars up to an overall multiplicative factor of order unity for reasons other than just counting the fermionic degrees of freedom. 相似文献
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《Physics letters. [Part B]》1987,196(2):129-134
Baryogenesis in the reheating phase of the chaotic inflationary universe is investigated, taking into account the non-thermal production of baryon-number non-conserving Higgs bosons from an inflation field. It is found that the baryon asymmetry may have different signs depending on the reheat temperature. Furthermore a model is presented in which appear universes with various baryon/entropy ratio and also antimatter universes as well as our universe, even though CP violation has a definite sign. 相似文献
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In this paper, we study closed inflationary universe models using the Gauss–Bonnet Brane. We determine and characterize the existence of a universe with Ω>1, with an appropriate period of inflation. We have found that this model is less restrictive in comparison with the standard approach where a scalar field is considered. We use recent astronomical observations to constrain the parameters appearing in the model. 相似文献
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Extended and hyperextended inflationary models of the universe have been developed which avoid the extreme fine-tuning required by all previous approaches. The models also generate a new source of inhomogeneities that affect large-scale structure. The most surprising feature is the role that inflation can play in altering the nature of the gravitational force.This essay received the second award from the Gravity Research Foundation, 1990 —Ed. 相似文献
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V. M. Zhuravlev S. V. Chervon V. K. Shchigolev 《Journal of Experimental and Theoretical Physics》1998,87(2):223-228
The problem of determining a representation of the self-interaction potential in the form of a time dependence of the field
potential energy which admits the existence of an inflationary regime and the transition of evolution to a Friedmann regime
of asymptotic expansion is investigated within a cosmological model with a self-interacting scalar field. A variational formulation
of the slow-roll concept is introduced, and, on the basis thereof, an exact solution is constructed for the evolution of the
scale factor and the form of the self-interaction potential. A method based on representing the Einstein equations in the
form of a linear second-order equation is developed for constructing and analyzing exact cosmological solutions of these equations.
Selected types of potentials and the corresponding evolutions of the universe are investigated.
Zh. éksp. Teor. Fiz. 114, 406–417 (August 1998) 相似文献
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Using the Harrison-Zel dovich energy-density fluctuation spectrum predicted by the inflationary cosmology, we compute multipole moments of the cosmic blackbody temperature. Our results are independent of the details of non-linear galactic evolution. 相似文献
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A method of constructing and analyzing exact solutions for inflationary cosmology models with a self-action scalar by introducing
an effective self-action potential is suggested. On the basis of exact solutions for complete and “shortened” equations obtained
in the “slow-descent” approximation, their comparative analysis is made. It is shown that the results obtained for approximate
models that are conventionally used for comparison with experimental data may differ greatly from those for exact models because
of the structural instability of models with inflation.
Ul'anovsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 14–20, January, 2000. 相似文献