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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeOct 17th 2013
    • (edited Oct 17th 2013)

    Inspired by Matthew Ando’s talk at the Conference on twisted cohomology that I am currently attending, I finally typed up a note on

    • CommentRowNumber2.
    • CommentAuthorUrs
    • CommentTimeOct 18th 2013
    • (edited Oct 18th 2013)

    I have now added what I think is a (simple) formal proof that a Heis( WZW)Heis(\mathcal{L}_{WZW})-structure on some BB induces a GG-fiber \infty-bundle on BB equipped with a map to B nU(1) conn\mathbf{B}^n U(1)_{conn} which restricts on each fiver to WZW\mathcal{L}_{WZW}. (I still need an argument that this G-bundle is indeed G-principal).

    This is at

    Leaving the WZW-terminology aside, this is completely general and formal and has nothing specifically to do with the special situation.

    I am using the following general abstract statements, which I hope I am not mixed up about:

    1. dependent sum preserves fiber products (because limits over cospan diagram in the slice are computed as limits over the corresponding co-cone diagrams down in the base and the inclusion of a cospan diagram into its co-cone diagram is final)

    2. by the same argument dependent sum preserves effective epimorphisms .

    Maybe some abstractly-minded reader can help me see why the argument at the above link also shows GG-principality (if it does).

    • CommentRowNumber3.
    • CommentAuthorDavidRoberts
    • CommentTimeOct 18th 2013

    Isn’t there a universal version of this over BG?

    • CommentRowNumber4.
    • CommentAuthorUrs
    • CommentTimeOct 19th 2013
    • (edited Oct 19th 2013)

    Over BHeis( WZW)\mathbf{B} Heis(\mathcal{L}_{WZW}). That’s what I am trying to construct.

    So far I have explicit constructions in local models and I have a general formal argument that lifts from GG-cocycles to Heis( WZW)Heis(\mathcal{L}_{WZW}) cocycles induced GG-fiber \infty-bundles with an nn-connection on the total space that restricts on each fiber to WZW\mathcal{L}_{WZW}. What I am still lacking is a general formal argument that this GG-fiber bundle is the GG-principal bundle classified by the underlying GG-cocycle.

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeFeb 3rd 2015

    Prodded by discussion with Eric Sharpe, I have added to the entry pointers to the original articles by Jim Gates, such as Gates-Siegel 88.

    Then I have replaced some of the discussion in the entry by pointers to the meanwhile more comprehensive note cwzw. Eventually I’ll go back and turn this into nnLab material. For the moment I have just expanded the Idea-section a little bit, mentioning more of the story for the heterotic string.

    Much more needs to be done here.

    • CommentRowNumber6.
    • CommentAuthorperezl.alonso
    • CommentTimeOct 17th 2023

    So surely there’s also a notion of fibered Chern-Simons which has the same relation with fibered WZW as that of CS/WZW? Is this supposed to be related to the M2 brane worldvolume theory?

    • CommentRowNumber7.
    • CommentAuthorUrs
    • CommentTimeOct 17th 2023
    • (edited Oct 17th 2023)

    For the example of the heterotic current sector, yes.

    But for the GS-functionals I doubt it, because these super Lie algebra cocycles are not transgressive (as per eq. 180, 181, p. 40 here), I think. (I feel like I knew this for a fact once, but now I am just saying it from memory. Certainly no transgression is known.)

    This was actually the point in my evolution where I changed my mind from “Oh, everything is fundamentally Chern-Simons theory or its bounday theory.” To “Oh, no, yet more fundamentally everything is fundamentally a WZW model.” Because there are WZW-type theories which do not come from Chern-Simons type theories.

    • CommentRowNumber8.
    • CommentAuthorperezl.alonso
    • CommentTimeOct 17th 2023

    What does one make of that situation where cocycles are not transgressive? What is the meaning of the obstruction, and when can one add other cocycles so as to make the combination transgressive, in the spirit of a GS mechanism (though of course one cannot call this an “anomaly”)?

    • CommentRowNumber9.
    • CommentAuthorUrs
    • CommentTimeOct 17th 2023

    These are good questions to ask.