Spatially Covariant Gravity Theories with Two Tensorial Degrees of Freedom

Abstract

Within the general framework of spatially covariant theories of gravity, the speaker and his research team study the conditions for having only the two tensorial degrees of freedom. Generally, there are three degrees of freedom propagating in the theory, of which two are tensorial and one is of the scalar type. Through a detailed Hamiltonian analysis, they find two necessary and sufficient conditions to evade the scalar type degree of freedom. The first condition implies that the lapse-extrinsic curvature sector must be degenerate. The second condition ensures that the dimension of the phase space at each spacetime point is even, so that the scalar type degree of freedom is eliminated completely. The speaker and his research team also compare the results with the previous studies, and apply their formalism to a simple example, in which the Lagrangian is quadratic in the extrinsic curvature.

About the speaker

Mr. Yao Zhi-Bang received his BEng from Guangdong Pharmaceutical University in 2015 and MSc from Sun Yat-sen University in 2019 respectively. He is currently a PhD Student in Sun Yat-sen University. He was a recipient of National Scholarship for Postgraduates from Ministry of Education of the Mainland China in 2018.   

Mr. Yao research focuses on Modified Gravity, Early Universe Cosmology and Symmetries and Field Transformations.

About the program

For more information, please refer to the program website at http://iasprogram.ust.hk/particle_theory.