Generically large nongaussianity in small multifield inflation

摘要: If forthcoming measurements of cosmic photon polarization restrict the primordial tensor-to-scalar ratio to $r < 0.01$, small field inflation will be a principal candidate for origin universe. Here we show that multifield inflation, without hybrid mechanism, typically results in large squeezed nongaussianity. Small potentials contain multiple flat directions, often identified with gauge invariant directions supersymmetric potentials. We find unless these have equal slopes, nongaussianity arises. After identifying relevant differences between and two-field potentials, demonstrate latter naturally fulfill Byrnes-Choi-Hall conditions. Computations power spectrum, spectral index, bispectrum, reveal models which otherwise match observed perturbations, produce excludably if inflatons' unequal slopes.