Kac determinant and singular vector of the level N representation of Ding-Iohara-Miki algebra
Yusuke Ohkubo
TL;DR
The paper derives a closed-form Kac determinant for the level-$N$ representation of the Ding-Iohara-Miki (DIM) algebra, revealing how the PBW-type vectors form a basis for generic parameter choices. It achieves this by decomposing the level-$N$ representation into a deformed $W_N$ sector and a $U(1)$ Heisenberg sector via a linear boson transformation and employing screening currents to construct singular vectors, which in turn determine the determinant’s vanishing lines. A key result is that singular vectors of the DIM algebra coincide with generalized Macdonald functions, the q-deformed AFLT basis, with an explicit identification $|\chi_{\vec{r},\vec{s}}\rangle \propto |P_{\Theta_{\vec{r},\vec{s}}}\rangle$. The work connects DIM representation theory to AGT/Nekrasov structures by providing a complete basis and clear links between generalized and ordinary Macdonald functions, broadening the resonance with 5D gauge theories and $qW$-algebras.
Abstract
In this paper, we obtain the formula for the Kac determinant of the algebra arising from the level $N$ representation of the Ding-Iohara-Miki algebra. It is also discovered that its singular vectors correspond to generalized Macdonald functions (the q-deformed version of the AFLT basis).
