Post-inflationary preheating with weak coupling

Particle production in the background of an external classical oscillating field is a key process describing the stage of preheating after inflation. For sufficiently strong couplings between the inflaton and matter fields, this process is known to proceed non-perturbatively. Parametric resonance plays crucial role for bosonic fields in this case, and the evolution of the occupation numbers for fermions is non-perturbative as well. In the Minkowski space, parametric resonance for bosons and non-perturbative effects for fermions would still persist even in the case of weak coupling. In particular, the energy density of created bosons would grow exponentially with time. However, the situation is quite different in the expanding universe. We give a simple demonstration how the conditions of the expanding universe, specifically, redshift of the field modes, lead to the usual perturbative expressions for particle production by an oscillating inflaton in the case of weak couplings. The results that we obtain are relevant and fully applicable to the Starobinsky model of inflation.Comment: 17 pages; Phys. Lett. B 733, 201

PHYSICAL-TECHNICAL BASES FOR ELEMENT BASE OF OPTOELECTRONIC INFORMATION SYSTEMS

The aim is to develop the analysis and synthesis of the element base for performing numerical experiments on creating elements of the new generation optoelectronic systems. The analytical and numerical methods and test stands of the joined capillaries in the optical range have been applied. The total analysis of the characteristics in the regular and non-regular gradient structures at presence of the anisotropy and absorption has been performed firstly. The numerical experiments on the design and development of the functional elements and services of the optoelectronic systems have been performed firstly. The algorithms and application packages for optimal synthesis of the optoelectronics elements and devices have been introducedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio