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Creators/Authors contains: "Raskin, Sam"

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  1. We prove that cuspidal automorphic D D -modules have non-vanishing Whittaker coefficients, generalizing known results in the geometric Langlands program from G L n GL_n to general reductive groups. The key tool is a microlocal interpretation of Whittaker coefficients. We establish various exactness properties in the geometric Langlands context that may be of independent interest. Specifically, we show Hecke functors are t t -exact on the category of tempered D D -modules, strengthening a classical result of Gaitsgory (with different hypotheses) for G L n GL_n . We also show that Whittaker coefficient functors are t t -exact for sheaves with nilpotent singular support. An additional consequence of our results is that the tempered, restricted geometric Langlands conjecture must be t t -exact. We apply our results to show that for suitably irreducible local systems, Whittaker-normalized Hecke eigensheaves are perverse sheaves that are irreducible on each connected component of Bun G \operatorname {Bun}_G
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    Free, publicly-accessible full text available April 25, 2026
  2. We calculate the category of D D -modules on the loop space of the affine line in coherent terms. Specifically, we find that this category is derived equivalent to the category of ind-coherent sheaves on the moduli space of rank one de Rham local systems with a flat section. Our result establishes a conjecture coming out of the 3 d 3d mirror symmetry program, which obtains new compatibilities for the geometric Langlands program from rich dualities of QFTs that are themselves obtained from string theory conjectures. 
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  3. We establish some cohomological bounds in $$D$$ -module theory that are known in the holonomic case and folklore in general. The method rests on a generalization of the $$b$$ -function lemma for non-holonomic $$D$$ -modules. 
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  4. In quantum geometric Langlands, the Satake equivalence plays a less prominent role than in the classical theory. Gaitsgory and Lurie proposed a conjectural substitute, later termed the fundamental local equivalence . With a few exceptions, we prove this conjecture and its extension to the affine flag variety by using what amount to Soergel module techniques. 
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  5. Abstract Arinkin and Gaitsgory defined a category oftempered‐modules on that is conjecturally equivalent to the category of quasi‐coherent (not ind‐coherent!) sheaves on . However, their definition depends on the auxiliary data of a point of the curve; they conjectured that their definition is independent of this choice. Beraldo has outlined a proof of this conjecture that depends on some technology that is not currently available. Here we provide a short, unconditional proof of the Arinkin–Gaitsgory conjecture. 
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