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A family of discrete Schroedinger operators is investigated through scattering theory. The continuous spectrum of these operators exhibit changes of multiplicity, and some of these operators possess resonances at thresholds. It is shown…

Mathematical Physics · Physics 2024-03-27 V. Austen , D. Parra , A. Rennie , S. Richard

We prove an index formula for the Dirac operator acting on two-valued spinors on a $3$-manifold $M$ which branch along a smoothly embedded graph $\Sigma \subset M$, and with respect to a boundary condition along $\Sigma$ inspired by an…

Differential Geometry · Mathematics 2025-12-04 Andriy Haydys , Rafe Mazzeo , Ryosuke Takahashi

We prove a strengthening of the Grothendieck-Lefschetz hyperplane theorem for local Picard groups conjectured by Koll\'ar. Our approach, which relies on acyclicity results for absolute integral closures, also leads to a restriction theorem…

Algebraic Geometry · Mathematics 2013-02-14 Bhargav Bhatt , Aise Johan de Jong

We extend the Atiyah, Patodi, and Singer index theorem for first order differential operators from the context of manifolds with cylindrical ends to manifolds with periodic ends. This theorem provides a natural complement to Taubes'…

Differential Geometry · Mathematics 2019-02-20 Tomasz Mrowka , Daniel Ruberman , Nikolai Saveliev

We revisit a construction principle of Fredholm operators using Hilbert complexes of densely defined, closed linear operators and apply this to particular choices of differential operators. The resulting index is then computed with the help…

Functional Analysis · Mathematics 2020-06-19 Dirk Pauly , Marcus Waurick

We define a local intersection number for metrised line bundles over quasiprojective varieties with compact support and show the local arithmetic Hodge index theorem for this intersection number. As a consequence we obtain a uniqueness…

Algebraic Geometry · Mathematics 2025-04-23 Marc Abboud

We give an index formula for a class of Dirac operators coupled with unbounded potentials. More precisely, we study operators of the form P := D+ V, where D is a Dirac operators and V is an unbounded potential at infinity on a possibly…

K-Theory and Homology · Mathematics 2011-12-30 Catarina Carvalho , Victor Nistor

We derive a transgression formula for the renormalized Chern character of the Bismut superconnection in the context of end-periodic fiber bundles and families of end-periodic Clifford modules. The transgression is expressed in terms of the…

Differential Geometry · Mathematics 2025-08-11 Alex R. Taylor

We study a class of localized indices for the Dirac type operators on a complete Riemannian orbifold, where a discrete group acts properly, co-compactly and isometrically. These localized indices, generalizing the $L^2$-index of Atiyah, are…

Differential Geometry · Mathematics 2013-07-29 Bai-Ling Wang , Hang Wang

In this paper we study the cohomology of the geometric realization of linking systems with twisted coefficients. More precisely, given a prime $p$ and a $p$-local finite group $(S,\mathcal{F},\mathcal{L})$, we compare the cohomology of…

Algebraic Topology · Mathematics 2017-09-06 Rémi Molinier

Dirac operators and Dirac cohomology for Lie superalgebras of Riemannian type, introduced by Huang and Pand\v{z}i\'{c}, provide an effective tool for the study of unitarizable supermodules. In this article, we study these objects for Lie…

Representation Theory · Mathematics 2026-03-24 Steffen Schmidt

We define the gauge-equivariant index of a family of elliptic operators invariant with respect to the free action of a family $\GR \to B$ of Lie groups (these families are called ``gauge-invariant families'' in what follows). If the fibers…

K-Theory and Homology · Mathematics 2007-05-23 Victor Nistor

We give necessary and sufficient condition so that we have d-hypercyclicity for operators who map a holomorphic function to a partial sum of the Taylor expansion. This problem is connected with doubly universal Taylors series and this is an…

Complex Variables · Mathematics 2015-04-02 Vagia Vlachou

In this article we propose a definition of a procdh topos. We show that it encodes procdh excision, has bounded homotopy dimension and therefore is hypercomplete and admits a conservative family of fibre functors. We also describe the local…

Algebraic Geometry · Mathematics 2024-01-08 Shane Kelly , Shuji Saito

We consider a invariant Dirac operator D on a manifold with a proper and cocompact action of a discrete group G. It gives rise to an equivariant K-homology class [D]. We show how the index of the induced orbifold Dirac operator can be…

K-Theory and Homology · Mathematics 2007-05-23 Ulrich Bunke

We introduce and study the index morphism for G-invariant leafwise G-transversally elliptic operators on smooth closed foliated manifolds which are endowed with leafwise actions of the compact group G. We prove the usual axioms of excision,…

K-Theory and Homology · Mathematics 2021-03-17 Alexandre Baldare , Moulay-Tahar Benameur

Let $G$ be a connected, real semisimple Lie group. Let $K<G$ be maximal compact, and let $\Gamma < G$ be discrete and such that $\Gamma \backslash G$ has finite volume. If the real rank of $G$ is $1$ and $\Gamma$ is torsion-free, then…

K-Theory and Homology · Mathematics 2025-05-06 Hao Guo , Peter Hochs , Hang Wang

We provide an easily verifiable condition for local $k$-connectedness of an inverse limit of polyhedra.

General Topology · Mathematics 2019-02-19 G. C. Bell , A. Nagórko

We use twisted sheaves and their moduli spaces to study the Brauer group of a scheme. In particular, we (1) show how twisted methods can be efficiently used to re-prove the basic facts about the Brauer group and cohomological Brauer group…

Algebraic Geometry · Mathematics 2018-06-18 Max Lieblich

We establish the basics of the analysis of operators on coverings of manifolds with cylindrical ends with a group of deck transformations $\Gamma$. We prove the $\Gamma$-analogue of the Atiyah-Patodi-Singer formula for Dirac operators on…

Differential Geometry · Mathematics 2008-06-26 Boris Vaillant