Theory HEP Seminar

Quantum Gravity constraints as well as observational constraints

Vahid Kamali

Bou-Ali-Sina University

Evolution of the universe started from a hot and dense Big Bang point. Temperature fluctuation map of cosmic microwave background (CMB) radiation and initial seeds of large scale structures (LSS) are explained by an inflationary period in a very early time. Inflaton as quanta of inflation field is responsible for the accelerated expansion of the universe. Potentials of the self-interacting single field models are constrained by observational data as well as quantum gravity. Some forms of potential are rolled out by data of Planck satellite but the quantum gravity constraints roll out all models of inflation except warm inflation. In the standard model of inflation or cold inflation firstly universe expands where the inflaton rolls the nearly flat part of the potential and in the second part, the universe reheats where the inflaton oscillates around the minimum of the potential which leads to thermalized radiation dominated universe. String theory as the best model of quantum gravity forbids the oscillation around the minimum of the potential during the thermalized epoch of the reheating. But in the warm model of inflation thermalization happens during the expansion of the universe where the inflaton rolls nearly steep potential and the universe will be radiation dominated without any separated reheating part.