Weyl's law for the cuspidal spectrum of SL(n)

Imaginary Schur-Weyl duality

We study imaginary representations of the Khovanov-Lauda-Rouquier algebras of affine Lie type. Irreducible modules for such algebras arise as simple heads of standard modules. In order to define standard modules one needs to have a cuspidal system for a fixed convex preorder. A cuspidal system consists of irreducible cuspidal modules---one for each real positive root for the corresponding affine root system ${\tt X}_l^{(1)}$, as well as irreducible imaginary modules---one for each $l$-multipartition. We study imaginary modules by means of `imaginary Schur-Weyl duality'. We introduce an imagina…

Tame cuspidal representations in non-defining characteristics

Let F be a non-archimedean local field of odd residual characteristic p. Let G be a (connected) reductive group that splits over a tamely ramified field extension of F. We show that a construction analogous to Yu's construction of complex supercuspidal representations yields smooth, irreducible, cuspidal representations over an arbitrary algebraically closed field R of characteristic different from p. Moreover, we prove that this construction provides all smooth, irreducible, cuspidal R-representations if p does not divide the order of the Weyl group of G.

The Weyl law for congruence subgroups and arbitrary $K_\infty$-types

Let $G$ be a reductive algebraic group over $\mathbb{Q}$ and $Γ\subset G(\mathbb{Q})$ an arithmetic subgroup. Let $K_\infty\subset G(\mathbb{R})$ be a maximal compact subgroup. We study the asymptotic behavior of the counting functions of the cuspidal and residual spectrum, respectively, of the regular representation of $G(\mathbb{R})$ in $L^2(Γ\backslash G(\mathbb{R}))$ of a fixed $K_\infty$-type $σ$. A conjecture, which is due to Sarnak, states that the counting function of the cuspidal spectrum of type $σ$ satisfies Weyl's law and the residual spectrum is of lower order growth. Using the Ar…

Actions of relative Weyl groups I, II

In the first part, we construct a new isomorphism between the endomorphism algebra of an induced cuspidal character sheaf and the group algebra of the relative Weyl group involved. We show it differs from the isomorphism of Lusztig by a linear character, and we relate this linear character to some stabilizers. Some consequences for characteristic functions of character sheaves are obtained. In the second part, we compute explicitly this linear character whenever the cuspidal local system is supported by the regular unipotent class and, as an application of these methods, we obtain a refinement…

Weak Weyl's law for congruence subgroups

Let $G$ be a connected and simply connected semisimple algebraic group over $\Bbb Q$ and let $Γ\subset G(\Bbb Q)$ be an arithmetic subgroup. Let $K_\infty\subset G(\Bbb R)$ be a maximal compact subgroup and let $d$ be the dimension of the symmetric space $G({\mathbb R})/K_\infty$. Let $σ$ be an irreducible unitary representation of $K_\infty$. We prove that for every $Γ$ there exists a normal subgroup $Γ_1\subset Γ$ of finite index such that the quotient of the counting function of the $Γ_1$-cuspidal spectrum of weight $σ$ and $T^{d/2}$ has a positive lower bound as $T\to\infty$.

箭图 Hecke 超代数的虚 Schur-Weyl 对偶

Imaginary Schur-Weyl duality for quiver Hecke superalgebras

本文研究箭图 Hecke 超代数的虚尖代数，通过构造非负分次的 Morita 等价代数 C(n,d)，将其表示论归结为经典 Schur 代数，从而用多重分拆典范分类不可约模。