Resumen: We study reproducing kernel Hilbert spaces introduced as ranges of generalized Cesaro-Hardy operators, in one real variable and in one complex variable. Such spaces can be seen as formed by absolutely continuous functions on the positive half-line (or paths of infinite length) of fractional order, in the real case. A theorem of Paley-Wiener type is given which connects the real setting with the complex one. These spaces are related with fractional operations in the context of integrated Brownian processes. We give estimates of the norms of the corresponding reproducing kernels. Idioma: Inglés DOI: 10.1007/s13324-021-00558-5 Año: 2021 Publicado en: Analysis and Mathematical Physics 11, 3 (2021), 119 [34 pp] ISSN: 1664-2368 Factor impacto JCR: 1.57 (2021) Categ. JCR: MATHEMATICS rank: 65 / 333 = 0.195 (2021) - Q1 - T1 Categ. JCR: MATHEMATICS, APPLIED rank: 109 / 267 = 0.408 (2021) - Q2 - T2 Factor impacto CITESCORE: 2.4 - Mathematics (Q2)