Stochastic Calculus for Rough Fractional Brownian Motion via Operator Factorization

Fuente: arXiv
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Autor principal: Fontes, Ramiro
Formato: Preprint
Publicado: 2026
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author Fontes, Ramiro
author_facet Fontes, Ramiro
contents We develop an operator-theoretic formulation of stochastic calculus for fractional Brownian motion with Hurst parameter H in (0, 1/2). The approach is based on adjointness between stochastic integration and differentiation in the Cameron-Martin space of the driving process. For Gaussian Volterra processes, we establish a canonical factorization of fluctuations (Id - E) = delta_X Pi_X D_X, where D_X := delta_X^* is the operator-covariant derivative (adjoint of the stochastic integral), delta_X the divergence, and Pi_X the predictable projection. In the rough fractional regime, the factorization yields explicit derivative formulas for cylindrical functionals, controlled expansions of conditional expectations with O(|t-s|^{2H}) remainders, and an intrinsic identification of the Gubinelli derivative as the predictable component Pi_X D_X F. The framework extends to mixed semimartingale-rough processes, providing a unified calculus without requiring iterated integrals or signature constructions.
format Preprint
id arxiv_https___arxiv_org_abs_2601_09967
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stochastic Calculus for Rough Fractional Brownian Motion via Operator Factorization
Fontes, Ramiro
Probability
Primary 60H07, Secondary 60G15, 47N30
We develop an operator-theoretic formulation of stochastic calculus for fractional Brownian motion with Hurst parameter H in (0, 1/2). The approach is based on adjointness between stochastic integration and differentiation in the Cameron-Martin space of the driving process. For Gaussian Volterra processes, we establish a canonical factorization of fluctuations (Id - E) = delta_X Pi_X D_X, where D_X := delta_X^* is the operator-covariant derivative (adjoint of the stochastic integral), delta_X the divergence, and Pi_X the predictable projection. In the rough fractional regime, the factorization yields explicit derivative formulas for cylindrical functionals, controlled expansions of conditional expectations with O(|t-s|^{2H}) remainders, and an intrinsic identification of the Gubinelli derivative as the predictable component Pi_X D_X F. The framework extends to mixed semimartingale-rough processes, providing a unified calculus without requiring iterated integrals or signature constructions.
title Stochastic Calculus for Rough Fractional Brownian Motion via Operator Factorization
topic Probability
Primary 60H07, Secondary 60G15, 47N30
url https://arxiv.org/abs/2601.09967