@article{jeong_nekrasov_2020,
title={Riemann-Hilbert correspondence and blown up surface defects},
volume={2020},
DOI={10.1007/jhep12(2020)006},
abstractNote={Abstract
The relationship of two dimensional quantum field theory and isomonodromic deformations of Fuchsian systems has a long history. Recently four-dimensional N = 2 gauge theories joined the party in a multitude of roles. In this paper we study the vacuum expectation values of intersecting half-BPS surface defects in SU(2) theory with Nf = 4 fundamental hypermultiplets. We show they form a horizontal section of a Fuchsian system on a sphere with 5 regular singularities, calculate the monodromy, and define the associated isomonodromic tau-function. Using the blowup formula in the presence of half-BPS surface defects, initiated in the companion paper, we obtain the GIL formula, establishing an unexpected relation of the topological string/free fermion regime of supersymmetric gauge theory to classical integrability.},
number={12},
publisher={Springer Science and Business Media LLC},
author={Jeong, Saebyeok and Nekrasov, Nikita},
year={2020}
}