2 papers
math-ph2025
A permutation-based power series representation of the Baker-Campbell-Hausdorff formula
Joseph M. Jones, M. W. Long
The Baker-Campbell-Hausdorff formula was recently resummed exactly in one variable, and left as a power series in the other (Moodie and Long 2021 J. Phys. A: Math. Theor. 54 015208…
cond-mat.str-el2025
An explicit formula for perturbation theory at any order with infinitely many perturbations
Joseph M. Jones, M. W. Long
We provide a systematic formula, in terms of integer partitions, that generates perturbation theory explicitly at an arbitrary order. Our approach naturally includes an infinite nu…