Rational-Kernel Fractional Evolution Equations with Almost Sectorial Operators: A Resolvent Framework Unifying ABC and W Dynamics

Abstract: We study fractional evolution equations driven by rational-kernel time operators with non-singular memory, including the Atangana-Baleanu-Caputo operator and a generalized W-operator. These operators are characterized by Laplace symbols that do not necessarily belong to the classical Bernstein class. The analysis is carried out in the framework of almost sectorial operators, which allows resolvent estimates beyond standard analytic semigroup theory. Existence, uniqueness, and temporal regularity of mild solutions are established by Laplace transform techniques and contour integration, leading to the construction of associated resolvent families. A unified resolvent framework is developed, enabling a precise comparison between ABC and W dynamics and clarifying the influence of rational memory kernels on decay and smoothing properties. Several examples, including fractional diffusion-type equations, illustrate the abstract theory and highlight the impact of non-singular memory on long-time behavior.