Paper detail

Analytical Computation of Cosmological Correlators from Symmetries and Singularities

Cosmological correlators are very important objects in cosmology as they offer us a huge amount of information of the early universe. They reside on the future boundary of a de Sitter space and can be calculated by two methods. First method involves our old Lagrangian picture where we evaluate the bulk time integrals to find the correlator at the future boundary. The other method which is our main topic of interest is to find the correlators by imposing constraints from symmetries and singularities on the future boundary. Particularly, we obtain the differential equation satisfied by the correlator by imposing de Sitter isometries which act on the future boundary just like the conformal symmetry. Then we analytically solve this differential equation by imposing boundary conditions coming from the correct normalization of the physical singularities and absence of the unphysical ones. In the process we see emergence of the effects of time dependent background like particle production and also obtain their observable signatures in the correlators. Finally we compare our analytical solution with the numerical ones.