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I am a postdoc in maths with a degree in theoretical physics. I am interested in mathematical structures in quantum field theory and string theory, see here.
4h

awarded  Announcer 
14h

comment 
Extended TFT with coefficients in spans in any $\infty$topos
I should maybe say that the idea would be to use naturality of the equivalences in the case of $\infty$groupoids to reduce the desired equivalence in the case of general $\mathbf{H}$ to a presheaf of equivalences and then conclude from that. 
2d

asked  Extended TFT with coefficients in spans in any $\infty$topos 
Oct 15 
comment 
“extended TQFT” versus “TQFT with defects”
Yes, representations of cobordisms with singularities encode TFTs with boundaries and defects. For "prequantum" field theory this is discussed in sections 3.9.14.4 to 3.9.14.6 of arxiv.org/abs/1310.7930 (improved version in preparation at ncatlab.org/schreiber/show/Local+prequantum+field+theory). For quantization of this: arxiv.org/abs/1402.7041 . This is based on discussion with Domenico Fiorenza and Alessandro Valentino that recently appeared as arxiv.org/abs/1409.5723 
Oct 15 
awarded  Yearling 
Oct 13 
awarded  Announcer 
Sep 24 
awarded  Autobiographer 
Sep 15 
comment 
From 3framings on $\Sigma$ to $\mathrm{Spin}^c$structures on $\mathrm{Loc}_G(\Sigma)$?
Chris SchommerPries has kindly pointed out that there should be a positive answer to the second of my questions: the projectively flat Hitchin connection on the Riemann moduli space canonically lifts to a genuinely flat connection on the 3framing moduli space. This follows with a) Segal's deprojectivization, 2) the fact that "Atiyah 2framings" provide "level12 riggings" and 3) the observation (which Chris kindly highlighted) that there is a canonical functor from the 1type of 3framings to that of "Atiyah 2framings" (see ncatlab.org/nlab/show/modular+functor#TopologicalLift). 
Sep 11 
reviewed  Approve suggested edit on homotopy exact sequence for the étale fundamental group 
Sep 10 
comment 
When does a moduli space admit a spin structure?
There are of course moduli spaces which are both important and at the same time are geometrically simple, a key example being the (higher) Jacobians ncatlab.org/nlab/show/intermediate+Jacobian which are simply higher dimensional tori. Hence these even admit a framing and in particular admit whatever Gstructure you want. 
Sep 10 
revised 
From 3framings on $\Sigma$ to $\mathrm{Spin}^c$structures on $\mathrm{Loc}_G(\Sigma)$?
fixed trivial typos 
Sep 10 
revised 
From 3framings on $\Sigma$ to $\mathrm{Spin}^c$structures on $\mathrm{Loc}_G(\Sigma)$?
added 2 characters in body 
Sep 10 
asked  From 3framings on $\Sigma$ to $\mathrm{Spin}^c$structures on $\mathrm{Loc}_G(\Sigma)$? 
Sep 9 
comment 
Gaugetheoretic formulation of Maxwell equations
...apart from that saying that the EMfield is a U(1)principal connection is part of mathematical theory building in physics and not something one may derive from first principles. (Well, one may give some general arguments about the need for gauge fields to be modeled in differential cohomology, but I guess that's not what you are after.) 
Sep 9 
comment 
Gaugetheoretic formulation of Maxwell equations
Could you say what exactly you would want to see proven? There is the original Maxwell's equations from the 1850s not nvolving any principal bundles. Then there is Dirac's charge quantization argument from the 1930s which argues that this needs to be refined to the version where the electromagnetic field is a connection on a principal bundle. What one may derive is that this is the right structure to produce U(1)valued line holonomies, which are the gauge coupling action functionals of charged particles (electrons). But apart from that... 
Sep 7 
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Algebraic Ktheory and Homotopy Sheaves
Thanks, Adeel, this is good. Have added these references here: ncatlab.org/nlab/show/algebraic+Ktheory#Descent 
Sep 4 
reviewed  Approve suggested edit on Generalization of the equilateral triangle? 
Sep 4 
answered  Algebraic Ktheory and Homotopy Sheaves 
Aug 31 
awarded  Announcer 
Aug 29 
comment 
Does the notion of a “coherent state” exist in TQFTs? (ETQFTs?)
Maybe one should amplify that such definitions (ncatlab.org/nlab/show/coherent+state+in+geometric+quantization) hence depend on having "prequantum" data (often called "classical" data). If you instead have a quantizED field theory without the information of how it came about from quantizATION, say a TQFT or ETQFT given by (just) a functor/nfunctor, then these definitions of coherent state won't apply. 