Supersymmetries in the theory of W-algebras

Abstract: Let $\mathfrak{g}$ be a basic Lie superalgebra and $f$ be an odd nilpotent element in an $\mathfrak{osp}(1|2)$ subalgebra of $\mathfrak{g}$. We provide a mathematical proof of the statement that the W-algebra $W^k(\mathfrak{g},F)$ for $F=-\frac{1}{2}[f,f]$ is a vertex subalgebra of the SUSY W-algebra $W_{N=1}^k(\mathfrak{g},f)$, and that it commutes with all weight $\frac{1}{2}$ fields in $W_{N=1}^k(\mathfrak{g},f)$. Note that it has been long believed by physicists \cite{MadRag94}. In particular, when $f$ is a minimal nilpotent, we explicitly describe superfields which generate $W^k_{N=1}(\mathfrak{g},f)$ as a SUSY vertex algebra and their OPE relations in terms of the $N=1$ $\Lambda$-bracket introduced in \cite{HK07}. In the last part of this paper, we define $N=2,3$, and small or big $N=4$ SUSY vertex operator algebras as conformal extensions of $W^k_{N=1}(\mathfrak{sl}(2|1),f_{\text{min}})$, $W^k_{N=1}(\mathfrak{osp}(3|2),f_{\text{min}})$, $W^k_{N=1}(\mathfrak{psl}(2|2),f_{\text{min}})$, and $W^k_{N=1}(D(2,1;\alpha)\oplus \mathbb{C},f_{\text{min}})$, respectively, for the minimal odd nilpotent $f_{\text{min}}$, and examine some examples.