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Localizing virtual structure sheaves for almost perfect obstruction theories
Journal article   Open access   Peer reviewed

Localizing virtual structure sheaves for almost perfect obstruction theories

Young-Hoon Kiem and Michail Savvas
Forum of mathematics. Sigma, Vol.8, e61
2020
DOI: 10.1017/fms.2020.59
url
https://doi.org/10.1017/fms.2020.59View
Published (Version of record) Open Access

Abstract

Almost perfect obstruction theories were introduced in an earlier paper by the authors as the appropriate notion in order to define virtual structure sheaves and K-theoretic invariants for many moduli stacks of interest, including K-theoretic Donaldson-Thomas invariants of sheaves and complexes on Calabi-Yau threefolds. The construction of virtual structure sheaves is based on the K-theory and Gysin maps of sheaf stacks. In this paper, we generalize the virtual torus localization and cosection localization formulas and their combination to the setting of almost perfect obstruction theory. To this end, we further investigate the K-theory of sheaf stacks and its functoriality properties. As applications of the localization formulas, we establish a K-theoretic wall-crossing formula for simple $\mathbb{C} ^\ast $ -wall crossings and define K-theoretic invariants refining the Jiang-Thomas virtual signed Euler characteristics.
Mathematical Physics

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