Square root Euler classes and counting sheaves on Calabi-​Yau 4-​folds

Date: 
Thursday, March 25, 2021 - 2:00pm
Location: 
Zoom meeting.
Speaker: 
Richard Thomas
(Imperial College)

Abstract: I will explain a nice characteristic class of SO(2n,C) bundles in both Chow cohomology and K-​theory, and how to localise it to the zeros of an isotropic section. This builds on work of Edidin-​Graham, Polishchuk-​Vaintrob, Anderson and others. This can be used to construct an algebraic virtual cycle (and virtual structure sheaf) on moduli spaces of stable sheaves on Calabi-​Yau 4-​folds. It recovers the real derived differential geometry virtual cycle of Borisov-​Joyce but has nicer properties, like a torus localisation formula. Joint work with Jeongseok Oh (KIAS).

*Zoom link*:
Topic: Geometry/Topology Seminar
Time: Mar 25, 2021 02:00 PM Central Time (US and Canada)

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https://umsystem.zoom.us/j/92239111948?pwd=aEhMUC9RRXdTd05BR2JnQk5Qd2hxQT09

Meeting ID: 922 3911 1948
Passcode: 68582