Description
Before we ask what is the theory of quantum gravity, it is a legitimate quest to formulate a robust quantum field theory in curved spacetime (QFTCS). Several conceptual conundrums have been issues of concern over several decades because no S-matrix formulation is yet found in QFTCS. We argue that the institutional thinking of fixing the spacetime geometry, observers, and light cones and then quantizing the fields in that ”intuitively” or ”classically” fixed spacetime is the origin of the problem. In this talk, I shall present a new formalism of quantum field theory in curved spacetime based on the ”quantum first” approach which leads us to a consistent S-matrix formulation. I will explicitly discuss the unitary QFT formulation de Sitter spacetime and then present how this formalism naturally explains one of the prominent CMB anomalies called the hemispherical power asymmetry (HPA). Furthermore, I shall present a new prediction for HPA in the context of primordial gravitational waves.
