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We consider single-field inflation in light of string-motivated "swampland" conjectures suggesting that effective scalar field theories with a consistent UV completion must have field excursion $\Delta \phi \lesssim M_{\rm Pl}$, in combination with a sufficiently steep potential, $M_{\rm Pl} V_\phi/V \gtrsim {\cal O}(1)$. Here, we show that the swampland conjectures are inconsistent with existing observational constraints on single-field inflation. Focusing on the observationally favoured class of concave potentials, we map the allowed swampland region onto the $n_S$-$r$ "zoo plot" of inflationary models, and find that consistency with the Planck satellite and BICEP2/Keck Array requires $M_{\rm Pl} V_\phi/V \lesssim 0.1$ and $-0.02 \lesssim M_{\rm Pl}^2 V_{\phi\phi}/V < 0$, in strong tension with swampland conjectures. Extension to non-canonical models such as DBI Inflation does not significantly weaken the bound., Comment: 5 pages, 1 figure. The busy reader should skip directly to Fig. 1, where the swampland-allowed region is mapped onto the $n_S$-$r$ plane. v2: added discussion on the refined swampland conjecture, basic conclusions unchanged. v3: version accepted for publication in Class. Quant. Grav

In this letter, we investigate a closed FRW quantum model in the presence of an SO(3) gauge sector described by a non-Abelian Born–Infeld action. The SO(4)-invariant choice for the FRW metric is complemented with an SO(4)-symmetric ansatz for the gauge fields. Subsequently, we find classes of asymptotic solutions of the Wheeler–DeWitt equation. These solutions are interpreted according to the different dynamical regimes present in the model. We further remark that Born–Infeld corrections may enhance the tunnelling probability for the early universe. Some potential applications of Born–Infeld quantum cosmology are also discussed.

In this paper, we wish to investigate certain observable effects in the recently obtained wormhole solution of the Eddington-inspired Born–Infeld (EiBI) theory, which generalizes the zero-mass Ellis–Bronnikov wormhole of general relativity. The solutions of EiBI theory contain an extra parameter κ having the inverse dimension of the cosmological constant Λ, and which is expected to modify various general relativistic observables such as the masses of wormhole mouths, tidal forces and light deflection. A remarkable result is that a non-zero κ could prevent the tidal forces in the geodesic orthonormal frame from becoming arbitrarily large near a small throat radius (${r}_{0}\sim 0$) contrary to what happens near a small Schwarzschild horizon radius ($M\sim 0$). The role of κ in the flare-out and energy conditions is also analyzed, which reveals that the energy conditions are violated. We show that the exotic matter in the EiBI wormhole cannot be interpreted as a phantom ($\omega =\frac{{p}_{{\rm{r}}}}{\rho }\lt -1$) or ghost field ϕ of general relativity due to the fact that both ρ and p (r) are negative for all κ.