Reheating of the Universe, Gravitinos and Leptogenesis
Abstract
The early universe went through a phase of accelerated expansion called inflation. After inflation the field driving inflation, the inflaton, decays and its decay products thermalise and the universe reheats. The thermal universe now contains all the known particles and dark matter particles. Gravitinos are supersymmetric particles that also are produced and their presence has very adverse cosmological consequences. Mechanisms to suppress gravitino production make it difficult to produce the observed matter-antimatter asymmetry of the universe. We discuss aspects of how this issue can be resolved involving a detailed understanding of how the universe reheats after inflation.
26/10/2009 at 4:00 pm
Prof. A. M. Srivastava, IOP, BBSR
Colloquium
Lecture Hall Block A, Institute of Physics
Document Date:
Cosmic Microwave Background Radiation, Inflation and Relativistic Heavy-Ion Collisions.
Scenario of Materials Science at VECC with Cyclotron & ECR ion source
Abstract
Irradiation and Implantation studies are being regularly carried out at VECC with the room temperature cyclotron. Activities in Materials Science are having two dimensionalities-1) Studies on Nuclear Structural Materials with a view to assessing the damage in the context of applications to Nuclear reactors and 2) Studies on various novel materials like High Temperature and low temperature superconductors, novel oxides, polymers etc. with the purpose of extracting tailor made properties and understanding the basic mechanism in the process. The second aspect will be talked about. Recently, Superconducting Cyclotron with high energy heavy ions and 6.4GHz ECR ion source are being activated for the purpose of different experiments. The ongoing experiments using ECR source and the future plans will be highlighted.
Studies at the extreme limits of the nuclear chart have gainedmomentum in the last decade with the advent of new experimentalfacilities. The production of new exotic nuclei lead to the discoveryof several exciting new phenomena like for example, neutron skins andhalos in neutron-rich nuclei, and the novel decay mechanism of protonradioactivity in proton rich nuclei around the proton drip line. Ontheoretical grounds, the description of these new phenomena, apartfrom validating existing models in regions far from stability,requires the formulation of new theories. Recent developments in thisarea will be discussed
