Milne spacetime with conical defect: Some holographic studies

We initiate a holographic study of field theory in a time-dependent background with a conical defect. We focus on the Milne spacetime to which, in the absence of cosmological constant, at late time any hyperbolic Friedmann-Robertson-Walker metric flows. When the Milne vacuum is represented by the adiabatic one, we are able to compute the two point correlators of operators which are dual to the massive scalars in the bulk AdS-Milne spacetime background with a defect. We find, for both twisted and untwisted operators, the correlators can be represented as the sum over images. This sum can be carried out explicitly to write the results in compact forms.