Multiplicities of maximal weights of the $\hat{s\ell}(n) $-module $V(k\Lambda_0)$

TL;DR

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Contribution

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Abstract

Consider the affine Lie algebra $\hat{s\ell}(n)$ with null root $\delta$, weight lattice $P$ and set of dominant weights $P^+$. Let $V(k\Lambda_0), \, k \in \mathbb{Z}_{\geq 1}$ denote the integrable highest weight $\hat{s\ell}(n)$-module with level $k \geq 1$ highest weight $k\Lambda_0$. Let $wt(V)$ denote the set of weights of $V(k\Lambda_0)$. A weight $\mu \in wt(V)$ is a maximal weight if $\mu + \delta \not\in wt(V)$. Let $max^+(k\Lambda_0)= max(k\Lambda_0)\cap P^+$ denote the set of maximal dominant weights which is known to be a finite set. In 2014, the authors gave the complete description of the set $max^+(k\Lambda_0)$. In subsequent papers the multiplicities of certain subsets of $max^+(k\Lambda_0)$ were given in terms of some pattern-avoiding permutations using the associated crystal base theory. In this paper the multiplicity of all the maximal dominant weights of the $\hat{s\ell}(n) $-module $V(k\Lambda_0)$ are given generalizing the known results.