  We propose blowup equations for 6d little string theories which generalize
Nakajima-Yoshioka's blowup equations for the 4d/5d instanton partition
functions on Omega background. We find that unlike the blowup equations for
standard SQFTs, we need to sum over auxiliary magnetic fluxes on the blown-up $
\mathbb{P}^1$ for a non-dynamical 2-form gauge field which plays a role in
canceling the mixed anomalies of the gauge symmetries. We demonstrate with
explicit examples that the blowup equations, when combined with the modular
properties, can be solved in order to determine the elliptic genera of little
strings.

High Energy Physics - Theory