AGT, Burge pairs and minimal models

TL;DR

This paper refines the computation of conformal blocks in minimal models combined with free boson theories within the AGT correspondence, resolving ill-defined expressions by imposing specific state restrictions.

Contribution

It introduces a novel restriction on states in conformal blocks to produce well-defined AGT-related expressions in minimal models tensor free boson theories.

Findings

Validated the approach with 1-point torus conformal blocks

Confirmed the method with 6-point sphere conformal blocks in Ising models

Provided explicit conditions for state restrictions in the conformal blocks

Abstract

We consider the AGT correspondence in the context of the conformal field theory $M^{\, p, p^{\prime}}$ $\otimes$ $M^{H}$, where $M^{\, p, p^{\prime}}$ is the minimal model based on the Virasoro algebra $V^{\, p, p^{\prime}}$ labeled by two co-prime integers $\{p, p^{\prime}\}$, $1 < p < p^{\prime}$, and $M^{H}$ is the free boson theory based on the Heisenberg algebra $H$. Using Nekrasov's instanton partition functions without modification to compute conformal blocks in $M^{\, p, p^{\prime}}$ $\otimes$ $M^{H}$ leads to ill-defined or incorrect expressions. Let $B^{\, p, p^{\prime}, H}_n$ be a conformal block in $M^{\, p, p^{\prime}}$ $\otimes$ $M^{H}$, with $n$ consecutive channels $\chi_{i}$, $i = 1, \cdots, n$, and let $\chi_{i}$ carry states from $H^{p, p^{\prime}}_{r_{i}, s_{i}}$ $\otimes$ $F$, where $H^{p, p^{\prime}}_{r_{i}, s_{i}}$ is an irreducible highest-weight $V^{\, p, p^{\prime}}$-representation, labeled by two integers $\{r_{i}, s_{i}\}$, $0 < r_{i} < p$, $0 < s_{i} < p^{\prime}$, and $F$ is the Fock space of $H$. We show that restricting the states that flow in $\chi_{i}$ to states labeled by a partition pair $\{Y_1^{i}, Y_2^{i}\}$ such that $Y^{i}_{2, {\tt R}} - Y^{i}_{1, {\tt R} + s_{i} - 1} \geq 1 - r_{i}$, and $Y^{i}_{1, {\tt R}} - Y^{i}_{2, {\tt R} + p^{\prime} - s_{i} - 1} \geq 1 - p + r_{i}$, where $Y^{i}_{j, {\tt R}}$ is row-${\tt R}$ of $Y^{i}_j, j \in \{1, 2\}$, we obtain a well-defined expression that we identify with $B^{\, p, p^{\prime}, H}_n$. We check the correctness of this expression for ${\bf 1.}$ Any 1-point $B^{\, p, p^{\prime}, H}_1$ on the torus, when the operator insertion is the identity, and ${\bf 2.}$ The 6-point $B^{\, 3, 4, H}_3$ on the sphere that involves six Ising magnetic operators.