## On certain elements in the Bernstein center of $\mathbf {GL}_2$

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- by Sandeep Varma
- Represent. Theory
**17**(2013), 99-119 - DOI: https://doi.org/10.1090/S1088-4165-2013-00427-2
- Published electronically: February 6, 2013
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## Abstract:

Let $F$ be a nonarchimedean local field of residue characteristic $p$, and let $r$ be an odd natural number less than $p$. Using the work of Moy and Tadić, we find an element $z$ of the Bernstein center of $G = \mathbf {GL}_2(F)$ that acts on any representation $\pi$ of $G$ by the scalar $z(\pi ) = \operatorname {tr} \left (\operatorname {Frob} ; \left ( \operatorname {Sym}^r \circ \varphi _{\pi }\right )^{I_F} \right )$, the trace of any geometric Frobenius element $\operatorname {Frob}$ of the absolute Weil group $W_F$ of $F$, acting on the inertia-fixed points of the representation $\operatorname {Sym}^r \circ \varphi _{\pi }$ of $W_F$, where $\varphi _{\pi } : W_F \rightarrow \hat {G}$ is the restriction to $W_F$ of the Langlands parameter of $\pi$. This element $z$ is specified by giving the functions obtained by convolving it with the characteristic functions of a large class of compact open subgroups of $G$, that includes all the groups of both the congruence and the Iwahori filtrations of $G$ having depth at least one.## References

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## Bibliographic Information

**Sandeep Varma**- Affiliation: Department of Mathematics, University of Chicago, 5734 University Avenue, Chicago, Illinois 60637
- Address at time of publication: School of Mathematics, Tata Institute of Fundamental Research, Colaba, Mumbai - 400 005, India
- Email: sandeepv@math.tifr.res.in
- Received by editor(s): December 23, 2011
- Received by editor(s) in revised form: August 19, 2012
- Published electronically: February 6, 2013
- © Copyright 2013
American Mathematical Society

The copyright for this article reverts to public domain 28 years after publication. - Journal: Represent. Theory
**17**(2013), 99-119 - MSC (2010): Primary 22E50, 22E35
- DOI: https://doi.org/10.1090/S1088-4165-2013-00427-2
- MathSciNet review: 3017263