Posts by Urs Schreiber

Postdoctoral Position at the interface of Algebra, Conformal Field Theory and String Theory (Dec 5, 2006)
Postdoc position in algebra, CFT and strings.
The n-Category Café (Aug 17, 2006)
New group blog: “The n-Category Cafe”.
Synthetic Transitions (Jul 28, 2006)
On deriving 2-connection transition laws using synthetic differential geometry.
Quillen's Superconnections -- Functorially (Jul 26, 2006)
On how to interpret the superconnections appearing on brane/anti-brane configurations in terms of functorial transport.
K-Theory for Dummies, II (Jul 26, 2006)
Some remarks on K-theory and D-branes.
Brodzki, Mathai, Rosenberg & Szabo on D-Branes, RR-Fields and Duality (Jul 20, 2006)
Mathai et al give a detailed analysis of the nature of D-branes, RR-charges and T-duality using and extending the topological/algebraic machinery known from “topological T-duality”.
2-Palatini (Jul 19, 2006)
Some remarks on formulations of (super)gravity in terms of n-connections.
Herbst, Hori & Page on Equivalence of LG and CY (Jul 18, 2006)
Hori and Herbst on equivalence of Landau-Ginzburg and Calabi-Yau TFT models using gauged linear sigma models.
Gomi on Reps of p-Form Connection Quantum Algebras (Jul 14, 2006)
Gomi on the construction of projective unitary reps of centrally extended groups of p-form connections.
Seminar on 2-Vector Bundles and Elliptic Cohomology, VI (Jul 13, 2006)
More detials on elliptic curves, formal groups and “classical” elliptic cohomology.
Freed, Moore, Segal on p-Form Gauge Theory, II (Jul 11, 2006)
On Heisenberg groups appearing in the quantization of higher chiral gauge theories.
Freed, Moore, Segal on p-Form Gauge Theory, I (Jul 10, 2006)
Some aspects of recent work by Freed, Moore and Segal on the quantum theory of abelian p-form fields and the grading of the Hilbert space by electric and magnetic flux modulo torsion.
How many Circles are there in the World? (Jul 8, 2006)
On 2-torsors for suspended U(1).
Gomi on Chern-Simons terms and central extensions of gerbe gauge groups (Jul 5, 2006)
Gomi on Chern-Simons field theories in higher dimensions and central extension of gerbe gauge groups.
Seminar on 2-Vector Bundles and Elliptic Cohomology, V (Jun 28, 2006)
Part V of a seminar on elliptic cohomology and 2-vector bundles. Review of relations between elliptic cohomology and strings.
Gukov on Surface Operators in Gauge Theory and Categorification (Jun 27, 2006)
Gukov relates knot theory to categorified quantum mechanics and the like.
Kapranov and Getzler on Higher Stuff (Jun 22, 2006)
Lecture notes of talks by Kapranov on noncommutative Fourier transformation and by Getzler on Lie theory of L_oo algebras.
Varieties and Schemes for Dummies, Part III (Jun 22, 2006)
Still more notes on elements of algebraic geometry.
Varieties and Schemes for Dummies, Part II (Jun 22, 2006)
More notes on elements of algebraic geometry.
Sharpe on Derived Categories and Strings on Stacks (Jun 21, 2006)
Slides of Eric Sharpe’s ESI talk on derived categories, strings on stacks and renormalization group flow.
Varieties and Schemes for Dummies, Part I (Jun 20, 2006)
Notes on elements of algebraic geometry.
Kapustin on SYM, Mirror Symmetry and Langlands, III (Jun 17, 2006)
The third part of the lecture.
Kapustin on SYM, Mirror Symmetry and Langlands, II (Jun 17, 2006)
Second part of A. Kapustin’s talk.
Soibelman on NCG of CFT and Mirror Symmetry (Jun 16, 2006)
Soibelman on collaps of CFTs on noncommutative target spaces.
Kapustin on SYM, Mirror Symmetry and Langlands, I (Jun 15, 2006)
Kapustin lectures on mirror symmetry in twisted compactified SYM, realizing geometric Langlands.
Roberts on Nonabelian Cohomology (Jun 15, 2006)
An old reference to a paper by Roberts on nonabelian cohomology.
Kontsevich Lectures on Mirror Symmetry, I (Jun 14, 2006)
Kontsevich lectures on mirror symmetry I: TQFTs and CohFTs.
Castellani on FDA in SuGra: gauge 3-group of M-Theory (Jun 12, 2006)
Castellani uses free differential algebra, and implictly Line n-algebra connections, for understanding the symmetries of 11D supergravity.
Homological Mirror Symmetry Literature (Jun 10, 2006)
Some literature on homological mirror symmetry and related issues.
Mathai on T-Duality IV: Distler on CFT Checks (Jun 10, 2006)
Jacques Distler comments on CFT checks of topological T-duality.
Crane-Sheppeard on 2-Reps (Jun 9, 2006)
On linear 2-reps as discussed by Crane and Sheppeard.
ESI Workshop on Homological Mirror Symmetry (Jun 4, 2006)
Kontsevich lectures at ESI on Homological Mirror Symmetry
Going the Wrong Way - for Dummies (Jun 2, 2006)
The definition of the pullback of sheaves of modules.
Mathai on T-Duality, III: Algebraic Formulation (Jun 2, 2006)
Mathai on elements of the C-star algebraic formulation of T-duality.
Mathai on T-Duality, II: T-dual K-classes by Fourier-Mukai (Jun 2, 2006)
First part of V. Mathai’s talk on topological T-duality: T-dual K-classes by means of Fourier-Mukai transformation.
Mathai on T-Duality, I: Overview (Jun 2, 2006)
Some elements of T-duality in the context of noncommutative topology. Part I: some context.
Fourier-Mukai, T-Duality and other linear 2-Maps (Jun 1, 2006)
Examples for linear 2-maps.
2-Spectral Theory, Part II (May 30, 2006)
Complete 2-bases of 2-eigenvectors (with an eye on Hecke eigensheaves and duality defects).
Some Links (May 29, 2006)
A paper on TQFT and String Topology, some lecture notes on derived categories and a paper on TCFT.
2-Spectral Theory, Part I (May 29, 2006)
Does a categorified spectral theorem connect duality defects in CFT with diagonizable Hecke-like 2-operators?
2-Metric Geometry (May 25, 2006)
Categorifying Lawvere’s conception of metric spaces.
Bunke on H, Part III (May 23, 2006)
Second part of U. Bunke’s talk on how to realize twisted deRham cohomology in terms of cohomology on gerbes.
Bunke on H, Part II (May 23, 2006)
Transcript of talk by U. Bunke on twisted cohomology and cohomology on gerbes.
Bunke on H, Part I (May 23, 2006)
U. Bunke et. al propose a (more) natural home for the twisted deRham cohomology appearing in Kalb-Ramond flux backgrounds.
The FRS Theorem on RCFT (May 19, 2006)
Statement of the FRS theorem in rational conformal field theory.
Hecke Eigensheaves and higher Eigenvectors (May 15, 2006)
More details on how Hecke eigensheaves are related to categorified eigenvectors.
Pantev on Langlands, II (May 10, 2006)
Pantev lectures on Langlands duality, D-branes and quantization, part II.
Pantev on Langlands, I (May 9, 2006)
Pantev lectures on Langlands duality, D-branes and quantization.
Eigenbranes and CatLinAlg (May 7, 2006)
The concept of eigenbranes, which appears in the context of geometric Langlands, and the categorified linear algebra of FRS.
Formal HQFT (May 4, 2006)
Porter and Turaev on formal HQFT.
Talk in Bonn on String 2-Group (Apr 26, 2006)
Talk on the String 2-Group in Bonn.
Huybrechts on Branes in K3, II (Apr 21, 2006)
Huybrechts analyzes the relation between topological and BPS branes on K3 surfaces, part II.
Huybrechts on Branes in K3, I (Apr 21, 2006)
Huybrechts analyzes the relation between topological and BPS branes on K3 surfaces.
Jurco on Gerbes and Stringy Applications (Apr 19, 2006)
Jurco reviews some facts concerning nonabelian gerbes in string theory.
A Note on RCFT and Quiver Reps (Apr 18, 2006)
A note on how the structure of RCFT is encoded in something very similar to a quiver representation.
(R)CFT on more general 2-Categories (Apr 18, 2006)
RCFTs can apparently be defined as 2-functors on 2-paths in Riemann surfaces. Can this be generalized to other domain 2-categories?
More Vietri Talks (Apr 16, 2006)
Talks on topological membranes and twisted K-theory
RR-Forms and Algebroids (Apr 12, 2006)
RR forms and free graded differential algebras.
Generalized Worldsheets? (Apr 12, 2006)
What is known about generalizations of world sheets away from the concept of manifolds?
Picard and Brauer 2-Groups (Apr 5, 2006)
On the Picard 2-group and the Brauer 2-group of a monoidal category.
More by Bartels on 2-Bundles (Apr 4, 2006)
Refined notes by Toby Bartels on 2-bundles.
Particles, Strings and the Early Universe in Hamburg (Apr 4, 2006)
A planned collaborative research center in Hamburg, on strings, HEP and cosmology.
Categorified Gauge Theory in Chicago (Apr 4, 2006)
Conference with emphasis on categorified gauge theory, covering gerbes and the String group.
String Localization, Once Again (Mar 29, 2006)
Recap of string localization.
Exotic String Statistics (Mar 28, 2006)
On generalizations of braid group statistics from points to strings.
Gerbes and Quantization (Mar 28, 2006)
Report on a paper on gerbes and quantization.
Cats in MathPhys (Mar 26, 2006)
List of applications of category theory in mathematical physics and string theory.
Stevenson, Henriques on String(n) (Mar 22, 2006)
Stevenson and Henriques have articles on the String group.
Remarks on 2-Reps (Mar 16, 2006)
More on 2-representations of the String(n) group.
Vertex Algebras et al. - Some Literature (Mar 14, 2006)
Literature on vertex algebras and related topics.
Gerbes and Quantum Field Theory (Mar 14, 2006)
Mickelsson on the role of gerbes in the study of anomalies in quantum field theory.
Remarks on String(n) (Mar 11, 2006)
Is Stolz/Teichner’s String-connection a 2-connection in an associated 2-bundle?
What IS a superfield, really? (Mar 7, 2006)
On the true (functorial) nature of superfields.
Hilbert Uniformization of Moduli Space (Mar 7, 2006)
On a result by Boedigheimer on Hilbert uniformization.
nEFT at Schloss Mickeln, Part II (Mar 6, 2006)
Talk by Johannes Ebert on CFT partition functions and modular forms.
nEFT at Schloss Mickeln, Part I (Mar 4, 2006)
Talk by E. Markert on concepts and results in describing generalized cohomology in terms of euclidean field theory. Part I. Mostly pesonal remarks on the general program.
Superpoints (Mar 2, 2006)
First notes from a workshop on elliptic objects.
Kapranov and Ganter on 2-Characters (Feb 27, 2006)
Ganter and Kapranov have a paper on traces and characters of 2-categorical representations of groups.
Graphs, Operads and Renormalization (Feb 23, 2006)
On a category of graphs appearing in Riemann surface moduli spaces and in renormalization theory.
On Transport Theory (Feb 17, 2006)
Overview of the theory of n-transport.
1st Northern German String workshop (Feb 12, 2006)
A string workshop at the ZMP.
Problemi Attuali di Fisica Teorica 06 (Feb 9, 2006)
This year’s meeting in Vietri.
Workshop on Gerbes, Groupoids and QFT (Feb 9, 2006)
Announcement of a workshop on gerbes and QFT.
FRS Reviews (Feb 8, 2006)
Two new reviews on FRS formalism.
Special Ambidextrous Adjunctions (Feb 8, 2006)
Question on special ambidextrous adjunctions.
Philosophy of Real Mathematics (Feb 7, 2006)
David Corfield on Jacob Lurie’s survey of elliptic cohomology.
Lauda & Pfeiffer on Open-Closed Topological Strings, II (Feb 6, 2006)
Lauda and Pfeiffer on open/closed topological strings from state sums.
Seminar on 2-Vector Bundles and Elliptic Cohomology, IV (Feb 5, 2006)
First session, third part.
Seminar on 2-Vector Bundles and Elliptic Cohomology, III (Feb 5, 2006)
First session, second part.
Seminar on 2-Vector Bundles and Elliptic Cohomology, II (Feb 3, 2006)
First session, first part.
Seminar on 2-Vector Bundles and Elliptic Cohomology, I (Feb 2, 2006)
Review of the 2-vector approach towards elliptic cohomology. Part I.
Exploring the Blogosphere (Feb 2, 2006)
Articles on math/physics weblogs.
Orbifold String Topology: Paths in Smooth Categories (Feb 2, 2006)
A 2-functorial conception of Lupercio & Uribe’s loop groupoid.
Moerdijk on Orbifolds, III (Feb 1, 2006)
Transcript of second of two lectures by I. Moerdijk on orbifolds.
Moerdijk on Orbifolds, II (Jan 31, 2006)
Transcript of first of two lectures by I. Moerdijk on orbifolds.
Moerdijk on Orbifolds, I (Jan 31, 2006)
I. Moerdijk lectures on the theory of orbifolds.
Spans, 2-Hilbert Spaces and Module Categories (Jan 27, 2006)
How to obtain 2-Hilbert spaces from span categories.
(String) Physics from (Higher) Algebra, II (Jan 24, 2006)
Some revisions on the program of categorifying quantum mechanics and relating it to string physics.
TCFT, Part I (Jan 10, 2006)
Some basic ideas of TCFT.
(String) Physics from (Higher) Algebra (Jan 9, 2006)
One further refinement of the tale called ‘Strings from categorified quantum mechanics.’
Nekrasov Lecture Online II (Jan 5, 2006)
The third session of Nikita Nekrasov’s lecture in Jerusalem. Some news on the Cech description of the pure spinor string.
Nekrasov Lecture Online I (Jan 4, 2006)
Quicktime video of Nikita Nekrasov’s lectures on the pure spinor superstring is available online.
Confusion and Connes Fusions (Jan 4, 2006)
Elements of Connes fusion.
Bimodules, Adjunctions and the Internal Hom, Part II (Jan 3, 2006)
More on bimodules, adjunctions, module categories and internal homs.
Bimodules, Adjunctions and the Internal Hom, Part I (Jan 2, 2006)
Notes on certain phenomena concerning algebra objects and adjunctions in tensor categories.
More by Gustavsson on Non-Abelian Strings (Jan 2, 2006)
More by A. Gustavsson on nonabelian strings
Winter School on Elliptic Objects (Dec 24, 2005)
Winter School on Elliptic Objects
Müger on Doplicher-Roberts (Dec 23, 2005)
Mueger has a new proof of Doplicher Roberts.
Equivariant Structures on Gerbes (Dec 23, 2005)
Some literature on gerbes on orbifolds.
Unoriented Strings and Gerbe Holonomy (Dec 22, 2005)
New preprint on gerbe holonomy over unoriented surfaces.
3D TFT Literature (Dec 20, 2005)
Literature on 3D TFT and its relation to 2D CFT.
Lauda on Frobenius Algebras and Open Topological Strings (Dec 15, 2005)
Lauda on Frobenius algebras and open topological strings and membranes.
Frobenius Algebras and 2D QFT (Dec 15, 2005)
On Frobenius algebras in 2D TFT and CFT.
Topological Strings from 2-Transport (Dec 14, 2005)
Fukuma-Hosono-Kawai TFT is obtained from 2-transport in Vect.
E. Sharpe on Derived Categories (Dec 13, 2005)
Encyclopedia article on derived categories by E. Sharpe.
D-Branes in Landau-Ginzburg Models (Dec 8, 2005)
Some elementary background on B-branes in LG models.
NABGs from 2-Transport I: Synthetic Bibundles (Dec 7, 2005)
Deriving nonabelian bundle gerbes from 2-functor 1-morphisms.
2-Connections on 2-Bundles (Dec 2, 2005)
2-connections on 2-bundles once again
"Area Metric" Manifolds (Nov 29, 2005)
On Schuller and Wohlfarth on area metric geometry and strings.
Line-2-Bundles and Bundle Gerbes (Nov 22, 2005)
On parallel transport of string in line-2-bundles.
CFT and SLE (Nov 15, 2005)
Notes on the SLE approach to CFT.
Lauda & Pfeiffer on Open-Closed Topological Strings (Nov 13, 2005)
Lauda and Pfeiffer fill some gaps in the rigorous understanding of open topological strings.
Strings on Stacks II (Nov 9, 2005)
More on Eric Sharpe and Tony Pantev on strings on stacks.
Strings on Stacks I (Nov 8, 2005)
Notes on E. Sharpe’s work on strings on stacks.
2-Equivariance and "Weak Pullback" (Nov 7, 2005)
On equivariant 2-bundles and strings on orbifolds.
Classical, Canonical, Stringy (Nov 2, 2005)
A stringy 3-form generalization of 2-form symplectic canonical mechanics.
Gerbes, strings, and Nambu brackets (Nov 1, 2005)
How are symplectic forms and Poisson brackets related to closed 3-forms and string physics?
Sheaves of CDOs (Oct 31, 2005)
Literature on Cech-methods in CFT.
Plasma-Ball Duals of Black Holes (Oct 27, 2005)
Aharony on plasma-ball duals to black holes and Berkooz on Q-ball excitations in MSSM as inflaton candidates.
ZMP Colloquium, Thursday: Nekrasov on Pure Spinor Superstring (Oct 20, 2005)
A talk by N. Nekrasov on the pure-spinor superstring and its apparent relation to gerbes.
Kalkkinen: Nonabelian Gerbes from twisted SYM (Oct 18, 2005)
Kalkkinen has a new paper where he points out relations between twisted SYM on 5-branes and nonabelian gerbes.
Synthetic Differential Geometry and Surface Holonomy (Oct 11, 2005)
Synthetic differential geometry and its use in the literature on higher gauge theory.
What is "the" Gerbe of a 2-Bundle? (Oct 5, 2005)
An observation on how a gerbe arises from a 2-bundle in an intrinsic (rather than cocyclic) way.
Literature on Exotic R4s (Sep 27, 2005)
Question on literature on exotic R4s.
Center for MathPhys Opening Colloquium in Hamburg (Sep 23, 2005)
Colloquium on mathematical aspects of string and field theory in Hamburg.
A. Gustavsson on Surface Holonomy (Sep 23, 2005)
A new proposal for nonabelian surface holonomy by Andreas Gustavsson.
Gerbes, Algebroids and Groupoid Bundles, the emerging Picture (Sep 2, 2005)
The big picture of gerbes, algebroids, groupoid bundles and some generalized geometry.
CFT, Gerbes and K-Theory in Oberwolfach, VII (Aug 24, 2005)
You’ll have noticed that I failed to report on the talks of the last two days in Oberwolfach, either…
Lecture Notes on Higher Gauge Theory (Aug 22, 2005)
John Baez’s lecture notes on Higher Gauge Theory, Homotopy Theory and n-Categories,
CFT, Gerbes and K-Theory in Oberwolfach, VI (Aug 20, 2005)
Jurco’s talk on classification of gerbes.
CFT, Gerbes and K-Theory in Oberwolfach, V (Aug 17, 2005)
Wednesday in Oberwolfach.
CFT, Gerbes and K-Theory in Oberwolfach, IV (Aug 16, 2005)
Tuesday in Oberwolfach: stacks, gerbes, M-theory and K-theory.
CFT, Gerbes and K-Theory in Oberwolfach, III (Aug 15, 2005)
Talks on gerbes in WZW models and some other stuff.
CFT, Gerbes and K-Theory in Oberwolfach, II (Aug 15, 2005)
Monday morning at Oberwolfach: M-theory for mathematicians and 2-gerbes for supergravity.
K-theory for dummies, I (Aug 12, 2005)
A list of some basic concepts in K-theory.
CFT, Gerbes and K-Theory in Oberwolfach, I (Aug 12, 2005)
On a workshop in Oberwolfach next week and some details on joint ideas with Igor Bakovic.
Q: Open Strings in KR Background (Jul 23, 2005)
How to understand the coupling of the KR field to open strings.
Costello on Open Topological Strings (Jul 17, 2005)
On a paper about open topological strings by K. Costello.
Talks in Hamburg, Lectures in Bad Honnef (Jul 15, 2005)
Random notes on HQFT and BCFT.
2-Holonomy in Terms of 2-Torsors (Jul 5, 2005)
Details on 2-holonomy in terms of 2-torsors and some pointers to the Streetfest conference.
From Loop Space Mechanics to Nonabelian Strings (Jun 23, 2005)
My thesis.
String(n), Part II (May 18, 2005)
Review of issues related to String(n).
String(n), Part I (May 18, 2005)
Review of issues related to String(n).
Nonabelian Weak Deligne Hypercohomology (May 17, 2005)
Generalizing Deligne cohomology to the nonabelian and weak case.
PSM and Algebroids, Part V (May 16, 2005)
Transitions in a p-bundle in terms of algebroid morphisms.
PSM and Algebroids, Part IV (May 13, 2005)
Last time I discussed how Lie pp-algebroids (and hence Lie pp-algebras) and dg-algebras on graded vector spaces of maximal…
PSM and Algebroids, Part III (May 4, 2005)
On the equivalence between algebroids, dg algebras and Lie p-algebras, the definition of algebroid YM theories and the relation to generalized geometry and abelian p-bundles and p-gerbes.
PSM and Algebroids, Part II (Apr 29, 2005)
How Courant algebroids gives rise to L_infinity algebras.
Akhmedov comments (Apr 20, 2005)
More on Akhmedov’s ideas concerning 2D TFTs.
Weak NABG (Apr 15, 2005)
On weak nonabelian bundle gerbes.
PSM and Algebroids, Part I (Apr 14, 2005)
There seem to be interesting relations of the Poisson σ\sigma-model (PSM) and of Lie algebroids to all kinds of…
Open topological strings (Apr 13, 2005)
Some literature on open topological strings.
Lessons from low Dimensions (Apr 9, 2005)
I am currently visting a CFT workshop at University of Bonn, Lessons from low Dimensions - the many Aspects of Conformal Field Theory.
New preprint: From Loop Groups to 2-Groups (and the String Group) (Apr 7, 2005)
We have a new preprint demonstrating a relation between weak Lie 2-algebras, 2-groups coming from centrally extended loop groups and the group String(n).
2-NCG: First Refinement (Apr 1, 2005)
Is 2-NCG an April Fool’s joke?
Akhmedov: Nonabelian 2-Holonomy using TFT (Mar 31, 2005)
Discussion of Akhmedov’s paper on 2-holonomy.
Derived Categories for Dummies, Part IV (Mar 22, 2005)
How branes and strings are described by the derived category of coherent sheaves.
Derived Categories for Dummies, Part III (Mar 20, 2005)
Elementary aspects of derived categories of quiver representations – plus a remark on how this relates to 2-bundles.
Derived Categories for Dummies, Part II (Mar 19, 2005)
Review of the definition of derived functors.
Rasetti: Quantum Computers based on TQFT (Mar 19, 2005)
Rasetti proposes that topological quantum field theories may be models for P=NP-quantumcomputers.
Talk at IIASS: Nonabelian Strings (Mar 16, 2005)
Slides for my talk at the IIASS on nonabelian strings.
Derived categories for dummies, Part I (Mar 13, 2005)
Some facts about derived categories. And an open question…
Quiver reps and vector 2-bundles (Mar 11, 2005)
A note on how quiver reps seem to be related to vector 2-bundles as in Baas,Dundas&Rognes.
What's next (Feb 24, 2005)
I have just returned from my two week visit of John Baez’s group at UC Riverside, which was extremely nice…
Project: 2-NCG (Feb 15, 2005)
A discussion of categorified NCG and its relation to superstrings.
Conversation with Kea: Categorified NCG (Feb 11, 2005)
Conversation with Kea on NCG and categorification.
Categorified Gauge Theory and M-Theory (Feb 9, 2005)
Does categorification of gauge theory know about the dimensions of the fundamental objects in M-theory?
2-Holonomy LEGO (Feb 3, 2005)
Category LEGO used to define and discuss global nonabelian 2-holonomy.
New paper: 2-Connections on 2-Bundles (Dec 30, 2004)
Mine and John Baez’s paper ‘2-connections on 2-bundles’ is available as a preprint.
Re: Categorified Gauge Theory (Dec 27, 2004)
Comments on how nonabelian surface holonomy relates to nonabelian volume integrals.
Nonabelian Self-Duality (Dec 15, 2004)
This is a followup to Peter Woit’s recent blog entry Langlands Program and Physics. There, Peter mentions the following…
Re: Category Theory and Physics (Dec 3, 2004)
Reply to Lubos’s comments on the last entry on categories and strings.
Categorified Points: Strings as Morphisms (Nov 24, 2004)
Over at sci.math.research there are some comments on categorification and its relation to string theory. Of course categories, being…
Weak groups, hard computation (Nov 18, 2004)
Results on 2-bundles with coherent structure 2-groups.
Nonabelian gerbes with connection and curving from 2-bundles with 2-holonomy (Nov 3, 2004)
A proof that a 2-bundle with 2-holonomy defines a nonabelian gerbe with certain connection and curving.
Thoughts on n-cube Scaling on 5-Branes (Oct 27, 2004)
Some thoughts on possible formal reasons for the n-cube scaling of degrees of freedom on 5-branes.
Re: Self-dual strings and M5-brane anomalies (Oct 22, 2004)
Comment on Lubos’ comment on Berman&Harvey’s Self-Dual String Anomalies.
2-bundles (Oct 19, 2004)
Finally there is a paper on 2-bundles.
Tensionless strings and Polyakov's loops (Oct 14, 2004)
Aspects of tensionless strings.
DDF=Pohlmeyer known in 1981 (Sep 16, 2004)
Readers of this blog will recall that I was involved in some thinking about Pohlmeyer invariants. It all started with…
States of string in non-abelian 2-form background (Sep 12, 2004)
Strings in non-abelian 2-form backgrounds again: Some conceptual issues.
r-flatness = 2-associativity (Aug 30, 2004)
I am further discussing loop space-, surface- and and 2-group-holonomy with those interested. While trying to convince the 2-group-theorists…
News release on emergent string spacetime (Aug 27, 2004)
My friend Rüdiger Vaas, who is working as a science journalist for the german science magazin Bild der Wissenschaft,…
On loop space and 2-group holonomy (Aug 27, 2004)
A pdf with my notes on the relation between loop space holonomy and 2-group holonomy is now available.
Why does 2-group theory miss surface holonomies with nonvanishing B+F? (Aug 24, 2004)
One more observation about the relation between 2-group theory and loop space holonomy.
1+1D LQG is really about boundary states (Aug 23, 2004)
What does LQG have to do with boundary states?
Super-Pohlmeyer invariants and boundary states for non-abelian gauge fields (Aug 20, 2004)
I have just submitted the following to the preprint server: Urs Schreiber: Super-Pohlmeyer invariants and boundary states for non-abelian…
Everybody agrees on the non-abelian boundary state! (Aug 19, 2004)
I realize that the different definitions of the non-abelian boundary state in the literature all agree.
Microscopic relation between loop space connections and 2-group holonomies (Aug 18, 2004)
I discuss how loop space holonomies and 2-group holonomies are related.
Escape from the Fog (Aug 16, 2004)
Report from vacation in Norway - and the inevitable remarks on some string theory.
On Holiday (Jul 30, 2004)
I’ll be on holiday the next two weeks.
A bird, a plane? No, super-Pohlmeyer! (Jul 27, 2004)
Recently I had talked about how I think Pohlmeyer invariants are related to boundary states of D-branes with gauge…
More remarks on flat loop space connections (Jul 23, 2004)
More comments on flat connections on loop space and their relation to surface holonomies.
Three ways to loop flatness (Jul 22, 2004)
Today I was contacted by Luiz Agostinho Ferreira who kindly called my attention to the paper Orlando Alvarez &…
To loose or not to loose information (Jul 22, 2004)
Comment on Hawking’s talk on the black hole information loss problem.
Talking to ’t Hooft about tossing TVs (Jul 19, 2004)
Summary of a talk by ’t Hooft.
Mathematical loop space literature (Jul 15, 2004)
Readers of my writings will have noticed that I mention the tem loop space from time to time. Now, I…
Nonabelian B-field equations of motion (Jul 13, 2004)
I try to derive the equations of motion of a nonabelian B-field from boundary state divergences.
Not Abelian - but Flat (Jul 12, 2004)
The crucial condition for non-abelian 2-form connections is their flatness in loop space.
Scandinavian but not Abelian (Jul 9, 2004)
I have attended a conference in Karlstad and thought about nonabelian 2-forms.
From Paris to Karlstad (via Bonn) (Jul 4, 2004)
I am preparing for talks in Bonn and Karlstad.
Cabinet de Curiosites dot com - STRINGS 04 (Jun 30, 2004)
The annual string theory conference is taking place at College de France in Paris this year. Fortunately this is…
Nonabelian 2-form connection from SCFT deformation (Jun 21, 2004)
I show how the loop space connection of a nonabelian 2-form arises from the obvious SCFT deformation.
Pohlmeyer invariants and states of the IIB matrix model (Jun 13, 2004)
Discussion of a relation between Pohlmeyer invariants and distributions of D(-1) branes which solve the IIB matrix model.
Open string backgrounds from boundary state deformations (Jun 11, 2004)
Review of some aspects of the boundary state deformation technique studied by Koji Hashimoto.
String entropy and black hole correspondence (Jun 10, 2004)
Brief summary of aspects of the string/black hole correspondence principle.
Experiments probing quantum gravity (Jun 10, 2004)
List of experiments that try to probe quantum gravity in one way or another.
Sigh. (Jun 7, 2004)
Bogdanov and Bogdanov have done it again.
CFTs from OSFT! (May 19, 2004)
The relation between classical SFT solutions and (boundary) conformal field theories is further discussed.
Referee reports on SCFT deformations and Pohlmeyer invariants (May 13, 2004)
Readers of this weblog will recall that we had discussed here two drafts which I have meanwhile submitted to JHEP….
Talk: N=2 NCG, fields and strings (May 3, 2004)
I am giving a talk at the Hamburg theory seminar on discrete NCG, fields and strings.
CFTs from OSFT? (Apr 29, 2004)
A comment about a relation between string field theory and deformed CFTs on the worldsheet.
Billiards at half-past E10 (Apr 26, 2004)
Aspects of sigma-models on Kac-Moody groups.
New York, New York (Apr 23, 2004)
I have visited Ioannis Giannakis in New York, discussing superfconformal deformations.
Power Supply (Apr 14, 2004)
I am visiting the AEI in Potsdam, discussing Pohlmeyer invariants and issues of quantization of string.
Billiards, random matrices, M-theory and all that (Apr 8, 2004)
I am currently at a seminar on quantum chaos and related stuff. You cannot enjoy meetings like these without…
Notions of string-localization (Mar 30, 2004)
Bert Schroer made me aware of the notion of ‘string-localized fields’, which are quite different from ordinary string fields.
Visualization of Superstring States (Mar 18, 2004)
Heuristic visualization of the massless states of superstring.
DPG Symposium 2004 (Mar 13, 2004)
I am on my way to the spring conference of the German Physical Society, the Frühjahrstagung der Deutschen Physikalischen Gesellschaft…
Introductory String Theory Seminar (Mar 11, 2004)
List of introductory literature for string theory.
Poll for sci.physics.strings (Mar 9, 2004)
Probably everybody has seen the Call for Votes for the creation of a new USENET newsgroup with the proposed…
Simple but not trivial (Mar 8, 2004)
Discussion of a paper concerned with constant R-R 2-form background in NSR formalism.
Before the flood (Mar 5, 2004)
On how to approach Type II strings by abstract differential calculus.
[Admin.] How to participate in the String Coffee Table dicussion (Feb 21, 2004)
A list of tips and tricks for how to participate in the discussion at the String Coffee Table.
The joy of IIB Matrix Models (Feb 20, 2004)
As readers of sci.physics.research might remember, a while ago I had learned about the IIB Matrix Model and had…
Torsion Gravity from String Theory (Feb 15, 2004)
I was asked by A. Pelster, who has worked on torsion gravity together with H. Kleinert and F. Hehl,…
[Review] DDF states (Jan 29, 2004)
The recent discussion about attempts to quantize the (super-)string by studying its algebra of classical invariants (i.e. of phase…
Pohlmeyer charges, DDF states and string-gauge duality (Jan 29, 2004)
It’s half past two in the morning here in central Europe and a can’t sleep because my brain is thinking…
Thiemann's quantization of the Nambu-Goto action (Jan 27, 2004)
Aspects of the recent paper by Th. Thiemann on the ‘LQG-string’ are discussed.
The search for discrete differential geometry (Jan 26, 2004)
At first it may look like a trivial problem whose solution should have been known for ages, being used…
[Review] Type II on AdS_3, Part I: Lightcone spectrum (Jan 26, 2004)
The calculation of the exact lightcone spectrum of superstrings on AdS_3 x S^3 is reviewed as a preparation for a demonstration of perturbative calculations of the same thing using curvature corrections to the Penrose limit.
[Exercise] Canonical analysis of D-string action (Jan 15, 2004)
The author tries to work his way through the canonical anaylsis of the D-string action. Help him! :-)
Classical deformations of 2d SCFTs - Part II: Algebra Isomorphisms (Dec 30, 2003)
It has been shown in Part I (see also hep-th/0401175) that the modes of the KK-deformed exterior derivative d…
Classical deformations of 2d SCFTs - Part I: Loop space (Dec 23, 2003)
Motivated by the representation of the classical super Virasoro constraints as generalized Dirac-Kaehler constraints (d±d +)|ψ⟩=0(\mathbf{d} \pm \mathbf{d}^+)|\psi\rangle =…
Cosmic F- and D-strings (Dec 17, 2003)
In the paper Copeland, Myers, Polchinski, Cosmic F- and D-strings the authors discuss cosmic strings and F/D-strings on the same…
deformation of SCFTs (Dec 15, 2003)
This environment is very inspiring, I’ll start with a couple of questions right away: :-) Is there anything known about…