Talk detail

Participant	Bhattacharya, Kaushik
Institution	Indian Institute of Technology, Kanpur - Flat 347, Indian Institute of Technology Campus - Kanpur - Uttar Pradesh - India

Session	GT3	Accepted	Yes	Order	6	Time	15:40
Talk	Oral abstract	Title	Geodesic flows and their deformations in Bertrand spacetimes
Co-authors	Prashant Kumar, Tapabrata Sarkar
Abstract	The Schwarzschild metric, remains one of the simplest yet most profound solutions of Einstein's field equations. One of the reasons for the popularity of the Schwarzschild solution among relativists is that it provides a realistic scenario to describe closed, stable orbits of planets and other heavenly objects. It is however known that there are other solutions of Einstein's equations which can also describe such stable, periodic motion. Two such examples were discovered some time ago which are called the ``Bertrand space-times'' (BSTs). Apart from being interesting from a purely theoretical perspective, BSTs might also be relevant for other reasons. For example, one possibility may be to model a realistic space-time that allows for bounded, periodic objects. Although such a possibility is rulrd out for normal matter due to the fact that asymptotically flat BSTs do not seem to satisfy the weak energy condition at infinity. Asymptotically non-flat BSTs are equally interesting objects, as these spacetimes can have singularities. In this talk the geodesic structure of BSTs and the possible singularities in the BSTs will be discussed.

Session	CM4	Accepted	Yes	Order	9	Time
Talk	Oral abstract	Title	Effect of Lee-Wick thermodynamics in the cosmology of the early universe
Co-authors	Suratna Das
Abstract	Lee and Wick proposed a finite theory of electrodynamics which included extra degrees of freedom. These extra degrees of freedom in a quantum field theory (QFT) manifest themselves as quantum fields with indefinite norms in the Hilbert space. Later on the Lee-Wick prescription for avoiding divergenses in QFTs was used to propose a higher derivative standard model (HDSM). The HDSM has one (or more) Lee-Wick partner for all the standard fields which may have indefinite norms. It can be shown that energy density and pressure from these fields turns out to be negative. If one combines the contribution of normal particles the energy density and pressure becomes positive. It is intersting to apply these thermodynamic results to the early universe which may have been infested with the Lee-Wick partners. In this talk I will focus on the various cosmological implications of such an early universe and show that in a Lee-Wick partner infested universe there can be a series of reheatings after the end of inflation.