Dynamical Field Inference and Supersymmetry
Abstract
Knowledge on evolving physical fields is of paramount importance in science, technology, and economics. Dynamical field inference (DFI) addresses the problem of reconstructing a stochastically driven, dynamically evolving field from finite data. It relies on information field theory (IFT), the information theory for fields. Here, the relations of DFI, IFT, and the recently developed supersymmetric theory of stochastics (STS) are established in a pedagogical discussion. In IFT, field expectation values can be calculated from the partition function of the full spacetime inference problem. The partition function of the inference problem invokes a functional Dirac function to guarantee the dynamics, as well as a fielddependent functional determinant, to establish proper normalization, both impeding the necessary evaluation of the path integral over all field configurations. STS replaces these problematic expressions via the introduction of fermionic ghost and bosonic Lagrange fields, respectively. The action of these fields has a supersymmetry, which means there exists an exchange operation between bosons and fermions that leaves the system invariant. In contrast to this, measurements of the dynamical fields do not adhere to this supersymmetry. The supersymmetry can also be broken spontaneously, in which case the system evolves chaotically. This affects the predictability of the system and thereby make DFI more challenging. We investigate the interplay of measurement constraints with the nonlinear chaotic dynamics of a simplified, illustrative system with the help of Feynman diagrams and show that the Fermionic corrections are essential to obtain the correct posterior statistics over system trajectories.
 Publication:

Entropy
 Pub Date:
 December 2021
 DOI:
 10.3390/e23121652
 arXiv:
 arXiv:2010.15414
 Bibcode:
 2021Entrp..23.1652W
 Keywords:

 Quantum Physics;
 High Energy Physics  Theory;
 Physics  Data Analysis;
 Statistics and Probability;
 3701
 EPrint:
 20 pages, 2 figures, 6 Feynman diagrams, 162 numbered equations