A covariant fermionic path integral for scalar Langevin processes with multiplicative white noise

Daniel G. Barci; Leticia F. Cugliandolo; Zochil González Arenas

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arXiv · 2602.17398

A covariant fermionic path integral for scalar Langevin processes with multiplicative white noise

Daniel G. Barci·Leticia F. Cugliandolo·Zochil González Arenas

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Abstract

We revisit the construction of the fermionic path-integral representation of overdamped scalar Langevin processes with multiplicative white noise, focusing on the covariance of the generating functional under non-linear changes of variables. We identify the transformations of the auxiliary (commuting and anticommuting) variables that ensure covariance under such transformations. The subtleties induced by the non-differentiable trajectories of the stochastic dynamics are encoded in the fermionic statistics. Upon integrating out the auxiliary variables, we derive the Onsager-Machlup formulation, which agrees with the one recently obtained using a higher-order discretization scheme. In contrast to the latter, the construction proposed here is formulated directly in continuous time.

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Daniel G. Barci, Leticia F. Cugliandolo, Zochil González Arenas. 2026-02-19. A covariant fermionic path integral for scalar Langevin processes with multiplicative white noise. https://arxiv.org/abs/2602.17398

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