Multi-Particle Cumulant Mapping for Coulomb Explosion Imaging: the Algorithm

Covariance mapping is widely used to study correlations of different variables in the dataset. The power of the method has been demonstrated in multi-particle imaging, including two- and three-body covariance on molecules of biological relevance and Coulomb explosion imaging (CEI) of molecular dissociation dynamics. While covariance for two particles is rather straightforward, for four-body correlations, one needs to extend covariance mapping to cumulant mapping, which has been tested in recent measurements of strong field ionization of formaldehyde. Here, I will discuss the details of how to compute cumulant mapping for the momentum sum of all four fragments of the formaldehyde molecule, and how one can perform the calculation with a faster and better algorithm.