Generalized Springer correspondence conjecture for graded Hecke algebras of type BnB_n

Let R0R_0 be a root system of type BnB_n, let \bbH\bbH be the associated graded Hecke algebra with long-root label k10k_1\neq 0 and short-root label k2=mk1k_2=mk_1, where m12Zm\in\frac{1}{2}\mathbb{Z}. Let Pn,2\mathcal{P}_{n,2} parametrize the irreducible representations of the Weyl group W0W_0, and let PA,BmP^m_{A,B} be the Green functions defined using the preorder determined by ama_m and m\sim_m. Write MAmM_A^m for the corresponding irreducible tempered module with real central character, and let VBV_B denote the irreducible W0W_0-module indexed by BB. Generalized Springer correspondence conjecture. The Green functions are independent of the chosen refinement of the preorder and are polynomials satisfying

PA,Bm(q)=l0PA,Bm;lql,degPA,Bmam(A).P^m_{A,B}(q)=\sum_{l\geq 0}P^{m;l}_{A,B}q^l,\qquad \deg P^m_{A,B}\leq a_m(A).

There is a bijection

\bbH^rcctempW0^,\widehat{\bbH}^{\mathrm{temp}}_{\mathrm{rcc}}\longleftrightarrow\widehat{W_0},

written MAmAM_A^m\leftrightarrow A, uniquely determined by the occurrence of χAϵ\chi_A\otimes\epsilon in MAmM_A^m when k1>0k_1>0 and of χA\chi_A when k1<0k_1<0. The modules are graded, with degree-ll part

MAm;l{BPB,Am;lVBϵ,k1>0,BPB,Am;lVB,k1<0,M_A^{m;l}\simeq\begin{cases} \displaystyle\sum_B P^{m;l}_{B,A}V_B\otimes\epsilon,&k_1>0,\\ \displaystyle\sum_B P^{m;l}_{B,A}V_B,&k_1<0, \end{cases}

and MAmM_A^m and MBmM_B^m have the same central character if and only if AmBA\sim_m B. This conjecturally extends the equal-label Springer-module description to unequal parameters; the paper reports verification for B3B_3 and B4B_4 at special parameters, while the general case remains open.

Sources & referencesView supporting material

Primary source

K. Slooten, “Generalized Green functions and graded Hecke algebras”, arXiv:math/0404202 (2004).

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