The canonical multi-scalar field inflation where the kinetic and potential terms are sum-separable is ruled out by the current observations for the chaotic-type potential $V=\sum_{ i} \mu_{ i} \phi_{ i}^{ p}$. This paper explores the non-sum-separable case to validate the chaotic-type potential in the multi-scalar field, incorporating a linear coupling term between the kinetic and potential terms in the canonical Lagrangian. This coupling influences the slow-roll parameters and also alters our predictions for the spectral index $n_{ s}$ and the tensor-to-scalar ratio $r$, which directly depend on those parameters. In fact, compared to standard canonical multi-field inflation, the values of $n_{ s}$ and $r$ decrease to levels consistent with the recent Planck+BICEP/Keck constraint.
Categories: gr-qc astro-ph.CO