KW-Euler Classes via Twisted Symplectic Bundles

Fuente: arXiv
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Auteur principal: D'Angelo, Alessandro
Format: Preprint
Publié: 2024
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author D'Angelo, Alessandro
author_facet D'Angelo, Alessandro
contents In this paper we are going to compute the $ \mathrm{KW} $-Euler classes for rank 2 vector bundles on the classifying stack $ \mathcal{B}N $, where $N$ is the normaliser of the standard torus in $SL_2$ and $\mathrm{KW}$ represents Balmer's derived Witt groups. Using these computations we will recover, through a new and different strategy, the formulas previously obtained by Levine in Witt-sheaf cohomology. In order to obtain our results, we will prove Künneth formulas for products of $GL_n$'s and $SL_n$'s classifying spaces and we will develop from scratch the basic theory of twisted symplectic bundles with their associated twisted Borel classes in $SL$-oriented theories.
format Preprint
id arxiv_https___arxiv_org_abs_2411_06504
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle KW-Euler Classes via Twisted Symplectic Bundles
D'Angelo, Alessandro
Algebraic Geometry
Algebraic Topology
K-Theory and Homology
In this paper we are going to compute the $ \mathrm{KW} $-Euler classes for rank 2 vector bundles on the classifying stack $ \mathcal{B}N $, where $N$ is the normaliser of the standard torus in $SL_2$ and $\mathrm{KW}$ represents Balmer's derived Witt groups. Using these computations we will recover, through a new and different strategy, the formulas previously obtained by Levine in Witt-sheaf cohomology. In order to obtain our results, we will prove Künneth formulas for products of $GL_n$'s and $SL_n$'s classifying spaces and we will develop from scratch the basic theory of twisted symplectic bundles with their associated twisted Borel classes in $SL$-oriented theories.
title KW-Euler Classes via Twisted Symplectic Bundles
topic Algebraic Geometry
Algebraic Topology
K-Theory and Homology
url https://arxiv.org/abs/2411.06504