A note on rank 5/2 Liouville irregular block, Painlevé I and the H $$ \mathcal{H} $$ 0 Argyres-Douglas theory

Abstract We study 4d type H $$ \mathcal{H} $$ 0 Argyres-Douglas theory in Ω-background by constructing Liouville irregular state of rank 5/2. The results are compared with generalized Holomorphic anomaly approach, which provides order by order expansion in Ω-background parameters ϵ 1,2. Another crucial test of our results provides comparison with respect to Painlevé I τ-function, which was expected to be hold in self-dual case ϵ 1 = −ϵ 2. We also discuss Nekrasov-Shatashvili limit ϵ 1 = 0, accessible either by means of deformed Seiberg-Witten curve, or WKB methods.