The impact of flowing three-body operators in the in-medium similarity renormalization group (IMSRG)

The IMSRG, a broadly applicable ab initio many-body method, is usually truncated by retaining only up to two-body operators during the RG evolution, with the effects of three-body operators assumed to be a small correction. Here we explore the impact of these three-body operators in tractable test cases, and discuss how insights gleaned can inform future improvements and uncertainty quantification.