A rigorous Keldysh functional integral for fermions
Published in Journal of Statistical Physics, 193(2), Article 28, 2026
This paper puts the Keldysh approach to non-equilibrium fermionic systems on firm mathematical ground. In practical terms, we prove that the functional-integral description has a well-defined continuum limit, and that key observables remain controlled as system size grows. We also derive explicit bounds that guarantee predictable decay of correlations under broad assumptions, including for general classes of dissipative quantum systems.
Recommended citation: Aretz, P. B. and Salmhofer, M. (2026). "A rigorous Keldysh functional integral for fermions." Journal of Statistical Physics, 193(2), 28. https://doi.org/10.1007/s10955-026-03583-5
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