Comment on “The phase diagram of the multi-matrix model with ABAB-interaction from functional renormalization”
Abstract Recently, [JHEP12 131 (2020)] obtained (a similar, scaled version of) the (a, b)-phase diagram derived from the Kazakov-Zinn-Justin solution of the Hermitian two-matrix model with interactions$$ -\mathrm{Tr}\left\{\frac{a}{4}\left({A}^4+{B}^4\right)+\frac{b}{2} ABAB\right\}, $$ − Tr a 4 A 4 + B 4 + b 2 ABAB , starting from Functional Renormalization. We comment on something unexpected: the phase diagram of [JHEP12 131 (2020)] is based on a βb-function that does not have the one-loop structure of the Wetterich-Morris equation. This raises the question of how to reproduce the phase diagram from a set of β-functions that is, in its totality, consistent with Functional Renormalization. A non-minimalist, yet simple truncation that could lead to the phase diagram is provided. Additionally, we identify the ensemble for which the result of op. cit. would be entirely correct.