A Resurgent Analytic Framework for Indicial Umbral Calculus via Mellin-Barnes and Borel-Laplace Theories

Abstract: Indicial umbral calculus offers an effective operational framework for manipulating transcendental functions, yet its analytic foundations have long remained only partially understood. In this work, we provide a rigorous analytic realisation of the theory grounded in Mellin-Barnes integrals, Borel-Laplace summation, and resurgent analysis. By elevating umbral operators from formal algebraic symbols to continuous linear functionals, we establish a topological duality akin to Gelfand-Shilov theory. Formal substitutions are thereby replaced by well-defined, continuous pairings between geometric kernels and suitably topologised admissible ground states. Within this framework, divergent umbral evaluations acquire a precise meaning: they emerge as sectorial asymptotic expansions of analytic functions reconstructed exactly by Mellin-Barnes integrals. The associated Stokes phenomena are natively encoded by jump functions in the spectral variable. This leads to a central spectral transmutation law relating entire and rational kernels directly through Gamma regularisation, proving that classical algebraic umbral identities are merely local expansions of a global analytic correspondence. The construction is systematically extended to general umbral functionals via the Pólya representation of entire functions of exponential type. Explicit examples - including Hankel contours, genuinely Barnes-type integrals, and Lerch transcendents - demonstrate the exact geometric resolution of formal algebraic obstructions. Ultimately, this approach embeds indicial umbral calculus within a unified functional-analytic and resurgent framework, where formal series, analytic continuation, and topological spectral data are intrinsically linked.