## June 8, 2010

### At “Geometry, Quantum Fields, and Strings: Categorial Aspects”

#### Posted by Urs Schreiber

This week at Oberwolfach takes place a workshop titled Geometry, Quantum Fields, and Strings: Categorial Aspects, organized by Peter Bouwknegt, Dan Freed, Christoph Schweigert.

The workshop’s webpage is here.

Posted at June 8, 2010 12:48 PM UTC

TrackBack URL for this Entry:   http://golem.ph.utexas.edu/cgi-bin/MT-3.0/dxy-tb.fcgi/2225

### Orientifold differential cohomology

Close to my heart today was the talk by Greg Moore on his work with Jacques Distler and Dan Freed (which we have talked about before here on various occasions) on the differential cohomology of orientifold backgrounds for string sigma-models.

The slides he pesented are available here:

Posted by: Urs Schreiber on June 8, 2010 1:21 PM | Permalink | Reply to this

### Differential T-duality

Yesterday Alexander Kahle told us about his work with Alessandro Valentino on refining the aspect of T-duality that is known as topological T-duality from an operation acting on just K-theory cocycles to an action on differential K-classes – the RR-fields:

Posted by: Urs Schreiber on June 8, 2010 3:49 PM | Permalink | Reply to this

### Tricategory of conformal nets

Not that I necessarily have to travel to hear about this, but Arthur Bartels gave another nice summary of the main result of

on the symmetric monoidal tricategory of conformal nets.

Posted by: Urs Schreiber on June 8, 2010 4:07 PM | Permalink | Reply to this

### A-oo-category valued FQFT from Lagrangian correspondence

Chris Woodward talked about his joint work with Kathrin Wehrheim on Lagrangian correspondences and $A_\infty$-category valued TFTs.

Posted by: Urs Schreiber on June 8, 2010 9:43 PM | Permalink | Reply to this

### Re: At Geometry, Quantum Fields, and Strings: Categorial Aspects

A bunch of us (Samson Abramsky, Peter Hines, Lou Kaufman, Sanjeevi Krishnan, Jimie Lawson, Gordon Plotkin, Jamie Vicary, …) are also in Germany, at Oberwolfach’s CS-counterpart Dagstuhl where The Semantics of Information organized by Mike Mislove and Keye Martin is taking place.

Posted by: bob on June 9, 2010 1:22 PM | Permalink | Reply to this

### At The Semantics of Information

A bunch of us […] are also in Germany, at Oberwolfach’s CS-counterpart Dagstuhl where The Semantics of Information organized by Mike Mislove and Keye Martin is taking place.

Then we should have a dedicated entry on this. If you would like to make a guest post, just send me some content by email (preferably code that also compiles in a comment-window here) and I’ll post it for you.

Posted by: Urs Schreiber on June 9, 2010 9:29 PM | Permalink | Reply to this

### Geometric and topological structures related to M-branes

Hisham Sati gave a brief survey of aspects of Geometric and topological structures related to M-branes.

Posted by: Urs Schreiber on June 10, 2010 2:25 AM | Permalink | Reply to this

### Motivic Donaldson-Thomas invariants

Yan Soibelman talked about his work with Maxim Kontsevich on motivic Donaldson-Thomas invariants (see there for a review).

Maybe I find time to post my notes later. But we were told tat just a few minutes before the talk, Maxim Kontsevich submitted a preprint with more details to the arXiv. So I suppose tomorrow I can to that, too.

By the way, a message to my fellow $n$-lab assistants: i haven’t been able to open the $n$-Forum page for days (I think precisely for the days that I am here in Oberwolfach): when I point my browser to it, it keeps loading and loading and loading, and nothing ever appears. So that’s why I haven’t been logging my recent edits.

Posted by: Urs Schreiber on June 10, 2010 11:40 AM | Permalink | Reply to this

### Re: Motivic Donaldson-Thomas invariants

That’s not a general problem with the n-Forum. It’s working for me and others.

Posted by: David Corfield on June 10, 2010 11:57 AM | Permalink | Reply to this

### Re: Motivic Donaldson-Thomas invariants

But we were told tat just a few minutes before the talk, Maxim Kontsevich submitted a preprint with more details to the arXiv. So I suppose tomorrow I can point to that, too.

As Zoran reminds me, it’s Cohomological Hall algebra, exponential Hodge structures and motivic Donaldson-Thomas invariants

Posted by: Urs Schreiber on June 15, 2010 7:10 PM | Permalink | Reply to this

### 2d TQFT and Filtrations of the moduli space of surfaces

Ezra Getzler gave again a talk on his work on the topology of the moduli space of punctured surfaces. By putting a filtration on this that reflects the $n$-categorical filtration of the modular operad, one can very efficiently read off various kinds of classication results of 2d TQFTs from the homotopy groups of the filtered subspaces.

I put my notes from his talk at 2d TQFT into the section Filtrations of the moduli space of surfaces.

Posted by: Urs Schreiber on June 10, 2010 1:41 PM | Permalink | Reply to this

### Witt classes of vertex operator algebras

Alexei Davydov spoke about how two vertex operator algebras may appear as the left and right chiral parts of a full 2d CFT precisely if their modular tensor categories of representations have the same Witt class.

Notes on the central statement I put into the section Full versus chiral CFT at conformal field theory.

I missed the reference to be given here, will try to provide it later.

Posted by: Urs Schreiber on June 10, 2010 4:22 PM | Permalink | Reply to this

### T-duality from path-integral reasoning

Kentaro Hori gave a review of the path-integral heuristic argument for seeing T-duality for the string on the circle. So I used the opportunity to add that part of the standard story to the $n$Lab entry, at Path integral heuristics deriving T-duality.

If I understand correctly then Kentaro Hori’s point is to give a particularly elegant collection of auxiliary fields on the worldsheet such that T-duality becomes manifest simply by integrating these out in two different orders.

He also did the superstring analog, but that I found too tedious to type out.

Posted by: Urs Schreiber on June 11, 2010 11:28 AM | Permalink | Reply to this

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