On spin structures and orientations for gauge-theoretic moduli spaces

Let X be a compact manifold, G a Lie group, P→X a principal G-bundle, and B_P the infinite-dimensional moduli space of connections on P modulo gauge. For a real elliptic operator E we previously studied orientations on the real determinant line bundle over B_P. These are used to construct orientatio...

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Main Authors: Joyce, D, Upmeier, M
Format: Working paper
Published: 2019
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author Joyce, D
Upmeier, M
author_facet Joyce, D
Upmeier, M
author_sort Joyce, D
collection OXFORD
description Let X be a compact manifold, G a Lie group, P→X a principal G-bundle, and B_P the infinite-dimensional moduli space of connections on P modulo gauge. For a real elliptic operator E we previously studied orientations on the real determinant line bundle over B_P. These are used to construct orientations in the usual sense on smooth gauge theory moduli spaces, and have been extensively studied since the work of Donaldson. Here we consider complex elliptic operators F and introduce the idea of spin structures, square roots of the complex determinant line bundle of F. These may be used to construct spin structures in the usual sense on smooth complex gauge theory moduli spaces. We study the existence and classification of such spin structures. Our main result identifies spin structures on X with orientations on X×S1. Thus, if P→X and Q→X×S1 are principal G-bundles with Q|X×{1}≅P, we relate spin structures on (B_P,F) to orientations on (B_Q,E) for a certain class of operators F on X and E on X×S1. Combined with arXiv:1811.02405, we obtain canonical spin structures for positive Diracians on spin 6-manifolds and gauge groups G=U(m),SU(m). In a sequel we will apply this to define canonical orientation data for all Calabi-Yau 3-folds X over the complex numbers, as in Kontsevich-Soibelman arXiv:0811.2435, solving a long-standing problem in Donaldson-Thomas theory.
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spelling oxford-uuid:c4e2db5f-4705-4ba8-a361-052547dd55552022-03-27T06:26:48ZOn spin structures and orientations for gauge-theoretic moduli spacesWorking paperhttp://purl.org/coar/resource_type/c_8042uuid:c4e2db5f-4705-4ba8-a361-052547dd5555Symplectic Elements at Oxford2019Joyce, DUpmeier, MLet X be a compact manifold, G a Lie group, P→X a principal G-bundle, and B_P the infinite-dimensional moduli space of connections on P modulo gauge. For a real elliptic operator E we previously studied orientations on the real determinant line bundle over B_P. These are used to construct orientations in the usual sense on smooth gauge theory moduli spaces, and have been extensively studied since the work of Donaldson. Here we consider complex elliptic operators F and introduce the idea of spin structures, square roots of the complex determinant line bundle of F. These may be used to construct spin structures in the usual sense on smooth complex gauge theory moduli spaces. We study the existence and classification of such spin structures. Our main result identifies spin structures on X with orientations on X×S1. Thus, if P→X and Q→X×S1 are principal G-bundles with Q|X×{1}≅P, we relate spin structures on (B_P,F) to orientations on (B_Q,E) for a certain class of operators F on X and E on X×S1. Combined with arXiv:1811.02405, we obtain canonical spin structures for positive Diracians on spin 6-manifolds and gauge groups G=U(m),SU(m). In a sequel we will apply this to define canonical orientation data for all Calabi-Yau 3-folds X over the complex numbers, as in Kontsevich-Soibelman arXiv:0811.2435, solving a long-standing problem in Donaldson-Thomas theory.
spellingShingle Joyce, D
Upmeier, M
On spin structures and orientations for gauge-theoretic moduli spaces
title On spin structures and orientations for gauge-theoretic moduli spaces
title_full On spin structures and orientations for gauge-theoretic moduli spaces
title_fullStr On spin structures and orientations for gauge-theoretic moduli spaces
title_full_unstemmed On spin structures and orientations for gauge-theoretic moduli spaces
title_short On spin structures and orientations for gauge-theoretic moduli spaces
title_sort on spin structures and orientations for gauge theoretic moduli spaces
work_keys_str_mv AT joyced onspinstructuresandorientationsforgaugetheoreticmodulispaces
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