Coset conformal field theory and instanton counting on C^2/Z_p

TL;DR

This paper explores a specific conformal field theory algebra related to instanton moduli spaces on orbifolded complex planes, providing new realizations and character identities that connect algebraic structures with geometric instanton counting.

Contribution

It introduces two realizations of the algebra (2,p) and demonstrates their equivalence, linking algebraic representations with instanton moduli space fixed points and partition functions.

Findings

Calculated characters match instanton fixed point generating functions.

Established two algebraic realizations connected to different instanton space compactifications.

Provided identities for characters of (2,p) related to instanton counting.

Abstract

We study conformal field theory with the symmetry algebra $\mathcal{A}(2,p)=\hat{\mathfrak{gl}}(n)_{2}/\hat{\mathfrak{gl}}(n-p)_2$. In order to support the conjecture that this algebra acts on the moduli space of instantons on $\mathbb{C}^{2}/\mathbb{Z}_{p}$, we calculate the characters of its representations and check their coincidence with the generating functions of the fixed points of the moduli space of instantons. We show that the algebra $\mathcal{A}(2,p)$ can be realized in two ways. The first realization is connected with the cross-product of $p$ Virasoro and $p$ Heisenberg algebras: $\mathcal{H}^{p}\times \textrm{Vir}^{p}$. The second realization is connected with: $\mathcal{H}^{p}\times \hat{\mathfrak{sl}}(p)_2\times (\hat{\mathfrak{sl}}(2)_p \times \hat{\mathfrak{sl}}(2)_{n-p}/\hat{\mathfrak{sl}}(2)_n)$. The equivalence of these two realizations provides the non-trivial identity for the characters of $\mathcal{A}(2,p)$. The moduli space of instantons on $\mathbb{C}^{2}/\mathbb{Z}_{p}$ admits two different compactifications. This leads to two different bases for the representations of $\mathcal{A}(2,p)$. We use this fact to explain the existence of two forms of the instanton pure partition functions.