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arXiv · 0712.0085

On some global problems in the tetrad approach to quasi-local quantities

Laszlo B Szabados
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Abstract

The potential global topological obstructions to the tetrad approach to finding the quasi-local conserved quantities, associated with closed, orientable spacelike 2-surfaces S, are investigated. First we show that the Lorentz frame bundle is always globally trivializable over an open neighbourhood U of any such S if an open neighbourhood of S is space and time orientable, and hence a globally trivializable SL(2,C) spin frame bundle can also be introduced over U. Then it is shown that all the spin frames belonging to the same spinor structure on S have always the same homotopy class. On the other hand, on a 2-surface with genus g, there are $2^{2g}$ homotopically different Lorentz frame fields, and there is a natural one-to-one correspondence between these homotopy classes and the different SL(2,C) spinor structures.

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Laszlo B Szabados. 2008-08-06. On some global problems in the tetrad approach to quasi-local quantities. https://doi.org/10.1088/0264-9381%2F25%2F19%2F195004

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