Bootstrapping a Higher-Derivative Cosmological Collider: Borel-Laplace Resummation and Stokes Phenomena

Abstract

We develop a higher-derivative cosmological bootstrap for massive spectators with quartic dispersion, $ω^2\propto k^4$, revealing a new boundary-value problem for inflationary correlators. The exchange equation becomes fourth order, and the collapsed limit becomes an irregular singular point, where collider and WKB branches coexist and exhibit Stokes phenomena. Since the folded configuration is now an ordinary point, the relativistic criterion of Bunch--Davies regularity at the folded singularity is no longer available. We instead impose an asymptotic boundary condition that removes the WKB branches and matches the surviving collider branches to Schwinger-Keldysh data. We also construct a convergent Borel-Laplace particular solution that resums a factorially divergent expansion and satisfies both bootstrap equations simultaneously; its leading collapsed-limit behavior is reproduced by direct in-in integrals. In the bispectrum, the squeezed-limit collider signal retains its mass-dependent frequency, while its amplitude and phase depend on the dispersion scale; near the equilateral configuration, the full shape is also sensitive to this scale and can change sign. Our results expose a new analytic structure of non-relativistic cosmological correlators and signatures beyond the squeezed limit.