Einstein or Jordan: seeking answers from the reheating constraints

Abstract

Distinguishing conformally coupled frames from the tree-level perturbative observables (scalar spectral index $n_{\mathrm{s}}$ and tensor-to-scalar ratio $r$) is challenging in cosmology as they are nearly identical. However, since the background evolution in these two frames differs significantly, we can look for potential signatures in the reheating constraints to discriminate these frames. In this work, we study the reheating phase in these frames and find that the difference in the inflationary energy scales in these frames contributes to a significant difference in the reheating e-folding number and hence, different reheating temperature. This difference will eventually lead to a contrasting thermal history in the two frames, which may have a potential observational signature in future observations. This study will open up an avenue for distinguishing various conformally connected otherwise indistinguishable frames and may finally lead us to the correct theory of gravity for our Universe.

arXiv comment5 pages, 2 figures

Cited by in corpus (6)

• Frame Covariance in Quantum Gravity
• Canonical Analysis of Brans-Dicke Theory Addresses Hamiltonian Inequivalence between Jordan and Einstein Frames
• Bounce from Inflation
• Stability of a viable non-minimal bounce
• Jordan and Einstein Frames from the perspective of $\omega =-3/2$ Hamiltonian Brans-Dicke theory
• Unifying inflationary and reheating solution