Comments on class S(YK)

A bstract We present a DSSYK-like interpretation of the Schur half-indices of 𝒩 = 2 SU(2) gauge theories with matter, in the presence of fundamental Wilson lines. The Schur half-indices of these theories can be understood as transition amplitudes in a non-vacuum sector of ordinary DSSYK. In the language of chord diagrams, the half-indices are obtained by summing over diagrams with special segments, which correspond to coherent states of the q -oscillator algebra. In addition, we show that the Schur half-index of SU(2) gauge theory with n F = 4 fundamental half-hypermultiplets corresponds to the partition function of a particle on the quantum disk.