Urs Schreiber: Postdoctoral Position at the interface of Algebra, Conformal Field Theory and String Theory (December 5, 2006)
Postdoc position in algebra, CFT and strings.
Robert H.: More polymer oscillators (October 31, 2006)
The same day as the “Lessons from the LQG string” appeared on hep-th, there was another paper by Corichi,…
Robert H.: Lessons from the LQG string (October 17, 2006)
It’s now two years, that Giuseppe and I have put out out our paper comparing the usual quantisation of…
Aaron: The Master constraint program in LQG (September 2, 2006)
I’m a little reluctant to post much on the master constraint program because I haven’t read much on it….
Aaron: The Harmonic Oscillator in LQG (September 2, 2006)
I’ve been trying to understand Thomas Thiemann’s riposte to the papers of Nicolai, Peeters and Zamaklar, Nicolai and Peeters…
Aaron: Not Even Wrong (August 19, 2006)
The physics blog-wars have hit the world of publishing with Peter Woit’s Not Even Wrong and Lee Smolin’s The Trouble…
Urs Schreiber: The n-Category Café (August 17, 2006)
New group blog: “The n-Category Cafe”.
Urs Schreiber: Synthetic Transitions (July 28, 2006)
On deriving 2-connection transition laws using synthetic differential geometry.
Urs Schreiber: Quillen’s Superconnections – Functorially (July 26, 2006)
On how to interpret the superconnections appearing on brane/anti-brane configurations in terms of functorial transport.
Urs Schreiber: K-Theory for Dummies, II (July 26, 2006)
Some remarks on K-theory and D-branes.
Urs Schreiber: Brodzki, Mathai, Rosenberg & Szabo on D-Branes, RR-Fields and Duality (July 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”.
Urs Schreiber: 2-Palatini (July 19, 2006)
Some remarks on formulations of (super)gravity in terms of n-connections.
Urs Schreiber: Herbst, Hori & Page on Equivalence of LG and CY (July 18, 2006)
Hori and Herbst on equivalence of Landau-Ginzburg and Calabi-Yau TFT models using gauged linear sigma models.
Urs Schreiber: Gomi on Reps of p-Form Connection Quantum Algebras (July 14, 2006)
Gomi on the construction of projective unitary reps of centrally extended groups of p-form connections.
Urs Schreiber: Seminar on 2-Vector Bundles and Elliptic Cohomology, VI (July 13, 2006)
More detials on elliptic curves, formal groups and “classical” elliptic cohomology.
Urs Schreiber: Freed, Moore, Segal on p-Form Gauge Theory, II (July 11, 2006)
On Heisenberg groups appearing in the quantization of higher chiral gauge theories.
Urs Schreiber: Freed, Moore, Segal on p-Form Gauge Theory, I (July 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.
Urs Schreiber: How many Circles are there in the World? (July 8, 2006)
On 2-torsors for suspended U(1).
Urs Schreiber: Gomi on Chern-Simons terms and central extensions of gerbe gauge groups (July 5, 2006)
Gomi on Chern-Simons field theories in higher dimensions and central extension of gerbe gauge groups.
Urs Schreiber: Seminar on 2-Vector Bundles and Elliptic Cohomology, V (June 28, 2006)
Part V of a seminar on elliptic cohomology and 2-vector bundles. Review of relations between elliptic cohomology and strings.
Urs Schreiber: Gukov on Surface Operators in Gauge Theory and Categorification (June 27, 2006)
Gukov relates knot theory to categorified quantum mechanics and the like.
Urs Schreiber: Kapranov and Getzler on Higher Stuff (June 22, 2006)
Lecture notes of talks by Kapranov on noncommutative Fourier transformation and by Getzler on Lie theory of L_oo algebras.
Urs Schreiber: Varieties and Schemes for Dummies, Part III (June 22, 2006)
Still more notes on elements of algebraic geometry.
Urs Schreiber: Varieties and Schemes for Dummies, Part II (June 22, 2006)
More notes on elements of algebraic geometry.
Urs Schreiber: Sharpe on Derived Categories and Strings on Stacks (June 21, 2006)
Slides of Eric Sharpe’s ESI talk on derived categories, strings on stacks and renormalization group flow.
Urs Schreiber: Varieties and Schemes for Dummies, Part I (June 20, 2006)
Notes on elements of algebraic geometry.
Urs Schreiber: Kapustin on SYM, Mirror Symmetry and Langlands, III (June 17, 2006)
The third part of the lecture.
Urs Schreiber: Kapustin on SYM, Mirror Symmetry and Langlands, II (June 17, 2006)
Second part of A. Kapustin’s talk.
Urs Schreiber: Soibelman on NCG of CFT and Mirror Symmetry (June 16, 2006)
Soibelman on collaps of CFTs on noncommutative target spaces.
Urs Schreiber: Kapustin on SYM, Mirror Symmetry and Langlands, I (June 15, 2006)
Kapustin lectures on mirror symmetry in twisted compactified SYM, realizing geometric Langlands.
Urs Schreiber: Roberts on Nonabelian Cohomology (June 15, 2006)
An old reference to a paper by Roberts on nonabelian cohomology.
Urs Schreiber: Kontsevich Lectures on Mirror Symmetry, I (June 14, 2006)
Kontsevich lectures on mirror symmetry I: TQFTs and CohFTs.
Urs Schreiber: Castellani on FDA in SuGra: gauge 3-group of M-Theory (June 12, 2006)
Castellani uses free differential algebra, and implictly Line n-algebra connections, for understanding the symmetries of 11D supergravity.
Urs Schreiber: Homological Mirror Symmetry Literature (June 10, 2006)
Some literature on homological mirror symmetry and related issues.
Urs Schreiber: Mathai on T-Duality IV: Distler on CFT Checks (June 10, 2006)
Jacques Distler comments on CFT checks of topological T-duality.
Urs Schreiber: Crane-Sheppeard on 2-Reps (June 9, 2006)
On linear 2-reps as discussed by Crane and Sheppeard.
Urs Schreiber: ESI Workshop on Homological Mirror Symmetry (June 4, 2006)
Kontsevich lectures at ESI on Homological Mirror Symmetry
Urs Schreiber: Going the Wrong Way - for Dummies (June 2, 2006)
The definition of the pullback of sheaves of modules.
Urs Schreiber: Mathai on T-Duality, III: Algebraic Formulation (June 2, 2006)
Mathai on elements of the C-star algebraic formulation of T-duality.
Urs Schreiber: Mathai on T-Duality, II: T-dual K-classes by Fourier-Mukai (June 2, 2006)
First part of V. Mathai’s talk on topological T-duality: T-dual K-classes by means of Fourier-Mukai transformation.
Urs Schreiber: Mathai on T-Duality, I: Overview (June 2, 2006)
Some elements of T-duality in the context of noncommutative topology. Part I: some context.
Urs Schreiber: Fourier-Mukai, T-Duality and other linear 2-Maps (June 1, 2006)
Examples for linear 2-maps.
Urs Schreiber: 2-Spectral Theory, Part II (May 30, 2006)
Complete 2-bases of 2-eigenvectors (with an eye on Hecke eigensheaves and duality defects).
Urs Schreiber: Some Links (May 29, 2006)
A paper on TQFT and String Topology, some lecture notes on derived categories and a paper on TCFT.
Urs Schreiber: 2-Spectral Theory, Part I (May 29, 2006)
Does a categorified spectral theorem connect duality defects in CFT with diagonizable Hecke-like 2-operators?
Urs Schreiber: 2-Metric Geometry (May 25, 2006)
Categorifying Lawvere’s conception of metric spaces.
Urs Schreiber: 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.
Urs Schreiber: Bunke on H, Part II (May 23, 2006)
Transcript of talk by U. Bunke on twisted cohomology and cohomology on gerbes.
Urs Schreiber: 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.
Urs Schreiber: The FRS Theorem on RCFT (May 19, 2006)
Statement of the FRS theorem in rational conformal field theory.
Urs Schreiber: Hecke Eigensheaves and higher Eigenvectors (May 15, 2006)
More details on how Hecke eigensheaves are related to categorified eigenvectors.
Urs Schreiber: Pantev on Langlands, II (May 10, 2006)
Pantev lectures on Langlands duality, D-branes and quantization, part II.
Urs Schreiber: Pantev on Langlands, I (May 9, 2006)
Pantev lectures on Langlands duality, D-branes and quantization.
Urs Schreiber: 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.
Urs Schreiber: Formal HQFT (May 4, 2006)
Porter and Turaev on formal HQFT.
Urs Schreiber: Talk in Bonn on String 2-Group (April 26, 2006)
Talk on the String 2-Group in Bonn.
Urs Schreiber: Huybrechts on Branes in K3, II (April 21, 2006)
Huybrechts analyzes the relation between topological and BPS branes on K3 surfaces, part II.
Urs Schreiber: Huybrechts on Branes in K3, I (April 21, 2006)
Huybrechts analyzes the relation between topological and BPS branes on K3 surfaces.
Urs Schreiber: Jurco on Gerbes and Stringy Applications (April 19, 2006)
Jurco reviews some facts concerning nonabelian gerbes in string theory.
Urs Schreiber: A Note on RCFT and Quiver Reps (April 18, 2006)
A note on how the structure of RCFT is encoded in something very similar to a quiver representation.
Urs Schreiber: (R)CFT on more general 2-Categories (April 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?
Urs Schreiber: More Vietri Talks (April 16, 2006)
Talks on topological membranes and twisted K-theory
Urs Schreiber: RR-Forms and Algebroids (April 12, 2006)
RR forms and free graded differential algebras.
Urs Schreiber: Generalized Worldsheets? (April 12, 2006)
What is known about generalizations of world sheets away from the concept of manifolds?
Urs Schreiber: Picard and Brauer 2-Groups (April 5, 2006)
On the Picard 2-group and the Brauer 2-group of a monoidal category.
Urs Schreiber: More by Bartels on 2-Bundles (April 4, 2006)
Refined notes by Toby Bartels on 2-bundles.
Urs Schreiber: Particles, Strings and the Early Universe in Hamburg (April 4, 2006)
A planned collaborative research center in Hamburg, on strings, HEP and cosmology.
Urs Schreiber: Categorified Gauge Theory in Chicago (April 4, 2006)
Conference with emphasis on categorified gauge theory, covering gerbes and the String group.
Urs Schreiber: String Localization, Once Again (March 29, 2006)
Recap of string localization.
Urs Schreiber: Exotic String Statistics (March 28, 2006)
On generalizations of braid group statistics from points to strings.
Urs Schreiber: Gerbes and Quantization (March 28, 2006)
Report on a paper on gerbes and quantization.
Urs Schreiber: Cats in MathPhys (March 26, 2006)
List of applications of category theory in mathematical physics and string theory.
Urs Schreiber: Stevenson, Henriques on String(n) (March 22, 2006)
Stevenson and Henriques have articles on the String group.
Urs Schreiber: Remarks on 2-Reps (March 16, 2006)
More on 2-representations of the String(n) group.
Urs Schreiber: Vertex Algebras et al. - Some Literature (March 14, 2006)
Literature on vertex algebras and related topics.
Urs Schreiber: Gerbes and Quantum Field Theory (March 14, 2006)
Mickelsson on the role of gerbes in the study of anomalies in quantum field theory.
Urs Schreiber: Remarks on String(n) (March 11, 2006)
Is Stolz/Teichner’s String-connection a 2-connection in an associated 2-bundle?
Urs Schreiber: What IS a superfield, really? (March 7, 2006)
On the true (functorial) nature of superfields.
Urs Schreiber: Hilbert Uniformization of Moduli Space (March 7, 2006)
On a result by Boedigheimer on Hilbert uniformization.
Urs Schreiber: nEFT at Schloss Mickeln, Part II (March 6, 2006)
Talk by Johannes Ebert on CFT partition functions and modular forms.
Urs Schreiber: nEFT at Schloss Mickeln, Part I (March 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.
Urs Schreiber: Superpoints (March 2, 2006)
First notes from a workshop on elliptic objects.
Urs Schreiber: Kapranov and Ganter on 2-Characters (February 27, 2006)
Ganter and Kapranov have a paper on traces and characters of 2-categorical representations of groups.
Urs Schreiber: Graphs, Operads and Renormalization (February 23, 2006)
On a category of graphs appearing in Riemann surface moduli spaces and in renormalization theory.
Urs Schreiber: On Transport Theory (February 17, 2006)
Overview of the theory of n-transport.
Urs Schreiber: 1st Northern German String workshop (February 12, 2006)
A string workshop at the ZMP.
Urs Schreiber: Problemi Attuali di Fisica Teorica 06 (February 9, 2006)
This year’s meeting in Vietri.
Urs Schreiber: Workshop on Gerbes, Groupoids and QFT (February 9, 2006)
Announcement of a workshop on gerbes and QFT.
Urs Schreiber: FRS Reviews (February 8, 2006)
Two new reviews on FRS formalism.
Urs Schreiber: Special Ambidextrous Adjunctions (February 8, 2006)
Question on special ambidextrous adjunctions.
Urs Schreiber: Philosophy of Real Mathematics (February 7, 2006)
David Corfield on Jacob Lurie’s survey of elliptic cohomology.
Urs Schreiber: Lauda & Pfeiffer on Open-Closed Topological Strings, II (February 6, 2006)
Lauda and Pfeiffer on open/closed topological strings from state sums.
Urs Schreiber: Seminar on 2-Vector Bundles and Elliptic Cohomology, IV (February 5, 2006)
First session, third part.
Urs Schreiber: Seminar on 2-Vector Bundles and Elliptic Cohomology, III (February 5, 2006)
First session, second part.
Urs Schreiber: Seminar on 2-Vector Bundles and Elliptic Cohomology, II (February 3, 2006)
First session, first part.
Urs Schreiber: Seminar on 2-Vector Bundles and Elliptic Cohomology, I (February 2, 2006)
Review of the 2-vector approach towards elliptic cohomology. Part I.
Urs Schreiber: Exploring the Blogosphere (February 2, 2006)
Articles on math/physics weblogs.
Urs Schreiber: Orbifold String Topology: Paths in Smooth Categories (February 2, 2006)
A 2-functorial conception of Lupercio & Uribe’s loop groupoid.
Urs Schreiber: Moerdijk on Orbifolds, III (February 1, 2006)
Transcript of second of two lectures by I. Moerdijk on orbifolds.
Urs Schreiber: Moerdijk on Orbifolds, II (January 31, 2006)
Transcript of first of two lectures by I. Moerdijk on orbifolds.
Urs Schreiber: Moerdijk on Orbifolds, I (January 31, 2006)
I. Moerdijk lectures on the theory of orbifolds.
Urs Schreiber: Spans, 2-Hilbert Spaces and Module Categories (January 27, 2006)
How to obtain 2-Hilbert spaces from span categories.
Urs Schreiber: (String) Physics from (Higher) Algebra, II (January 24, 2006)
Some revisions on the program of categorifying quantum mechanics and relating it to string physics.
Urs Schreiber: TCFT, Part I (January 10, 2006)
Some basic ideas of TCFT.
Urs Schreiber: (String) Physics from (Higher) Algebra (January 9, 2006)
One further refinement of the tale called ‘Strings from categorified quantum mechanics.’
Urs Schreiber: Nekrasov Lecture Online II (January 5, 2006)
The third session of Nikita Nekrasov’s lecture in Jerusalem. Some news on the Cech description of the pure spinor string.
Urs Schreiber: Nekrasov Lecture Online I (January 4, 2006)
Quicktime video of Nikita Nekrasov’s lectures on the pure spinor superstring is available online.
Urs Schreiber: Confusion and Connes Fusions (January 4, 2006)
Elements of Connes fusion.
Urs Schreiber: Bimodules, Adjunctions and the Internal Hom, Part II (January 3, 2006)
More on bimodules, adjunctions, module categories and internal homs.
Urs Schreiber: Bimodules, Adjunctions and the Internal Hom, Part I (January 2, 2006)
Notes on certain phenomena concerning algebra objects and adjunctions in tensor categories.
Urs Schreiber: More by Gustavsson on Non-Abelian Strings (January 2, 2006)
More by A. Gustavsson on nonabelian strings
Urs Schreiber: Winter School on Elliptic Objects (December 24, 2005)
Winter School on Elliptic Objects
Urs Schreiber: Müger on Doplicher-Roberts (December 23, 2005)
Mueger has a new proof of Doplicher Roberts.
Urs Schreiber: Equivariant Structures on Gerbes (December 23, 2005)
Some literature on gerbes on orbifolds.
Urs Schreiber: Unoriented Strings and Gerbe Holonomy (December 22, 2005)
New preprint on gerbe holonomy over unoriented surfaces.
Urs Schreiber: 3D TFT Literature (December 20, 2005)
Literature on 3D TFT and its relation to 2D CFT.
Urs Schreiber: Lauda on Frobenius Algebras and Open Topological Strings (December 15, 2005)
Lauda on Frobenius algebras and open topological strings and membranes.
Urs Schreiber: Frobenius Algebras and 2D QFT (December 15, 2005)
On Frobenius algebras in 2D TFT and CFT.
Urs Schreiber: Topological Strings from 2-Transport (December 14, 2005)
Fukuma-Hosono-Kawai TFT is obtained from 2-transport in Vect.
Urs Schreiber: E. Sharpe on Derived Categories (December 13, 2005)
Encyclopedia article on derived categories by E. Sharpe.
Urs Schreiber: D-Branes in Landau-Ginzburg Models (December 8, 2005)
Some elementary background on B-branes in LG models.
Urs Schreiber: NABGs from 2-Transport I: Synthetic Bibundles (December 7, 2005)
Deriving nonabelian bundle gerbes from 2-functor 1-morphisms.
Urs Schreiber: 2-Connections on 2-Bundles (December 2, 2005)
2-connections on 2-bundles once again
Urs Schreiber: “Area Metric” Manifolds (November 29, 2005)
On Schuller and Wohlfarth on area metric geometry and strings.
Urs Schreiber: Line-2-Bundles and Bundle Gerbes (November 22, 2005)
On parallel transport of string in line-2-bundles.
Robert H.: KK Reference (November 17, 2005)
I am looking for a reference for the fact that it is impossible to get non-abelian gauge groups or chiral…
Urs Schreiber: CFT and SLE (November 15, 2005)
Notes on the SLE approach to CFT.
Urs Schreiber: Lauda & Pfeiffer on Open-Closed Topological Strings (November 13, 2005)
Lauda and Pfeiffer fill some gaps in the rigorous understanding of open topological strings.
Urs Schreiber: Strings on Stacks II (November 9, 2005)
More on Eric Sharpe and Tony Pantev on strings on stacks.
Urs Schreiber: Strings on Stacks I (November 8, 2005)
Notes on E. Sharpe’s work on strings on stacks.
Urs Schreiber: 2-Equivariance and “Weak Pullback” (November 7, 2005)
On equivariant 2-bundles and strings on orbifolds.
Urs Schreiber: Classical, Canonical, Stringy (November 2, 2005)
A stringy 3-form generalization of 2-form symplectic canonical mechanics.
Urs Schreiber: Gerbes, strings, and Nambu brackets (November 1, 2005)
How are symplectic forms and Poisson brackets related to closed 3-forms and string physics?
Urs Schreiber: Sheaves of CDOs (October 31, 2005)
Literature on Cech-methods in CFT.
Urs Schreiber: Plasma-Ball Duals of Black Holes (October 27, 2005)
Aharony on plasma-ball duals to black holes and Berkooz on Q-ball excitations in MSSM as inflaton candidates.
Urs Schreiber: ZMP Colloquium, Thursday: Nekrasov on Pure Spinor Superstring (October 20, 2005)
A talk by N. Nekrasov on the pure-spinor superstring and its apparent relation to gerbes.
Urs Schreiber: Kalkkinen: Nonabelian Gerbes from twisted SYM (October 18, 2005)
Kalkkinen has a new paper where he points out relations between twisted SYM on 5-branes and nonabelian gerbes.
Urs Schreiber: Synthetic Differential Geometry and Surface Holonomy (October 11, 2005)
Synthetic differential geometry and its use in the literature on higher gauge theory.
Urs Schreiber: What is “the” Gerbe of a 2-Bundle? (October 5, 2005)
An observation on how a gerbe arises from a 2-bundle in an intrinsic (rather than cocyclic) way.
Urs Schreiber: Literature on Exotic R4s (September 27, 2005)
Question on literature on exotic R4s.
Urs Schreiber: Center for MathPhys Opening Colloquium in Hamburg (September 23, 2005)
Colloquium on mathematical aspects of string and field theory in Hamburg.
Urs Schreiber: A. Gustavsson on Surface Holonomy (September 23, 2005)
A new proposal for nonabelian surface holonomy by Andreas Gustavsson.
Robert H.: What does the density of vacua predict? (September 21, 2005)
Imagine a room where the floor has the profile (1)z(x,y)=sin(π/x). z(x,y) = \sin(\pi/x). Now, you throw a ball into…
Urs Schreiber: Gerbes, Algebroids and Groupoid Bundles, the emerging Picture (September 2, 2005)
The big picture of gerbes, algebroids, groupoid bundles and some generalized geometry.
Urs Schreiber: CFT, Gerbes and K-Theory in Oberwolfach, VII (August 24, 2005)
You’ll have noticed that I failed to report on the talks of the last two days in Oberwolfach, either…
Urs Schreiber: Lecture Notes on Higher Gauge Theory (August 22, 2005)
John Baez’s lecture notes on Higher Gauge Theory, Homotopy Theory and n-Categories,
Urs Schreiber: CFT, Gerbes and K-Theory in Oberwolfach, VI (August 20, 2005)
Jurco’s talk on classification of gerbes.
Urs Schreiber: CFT, Gerbes and K-Theory in Oberwolfach, V (August 17, 2005)
Wednesday in Oberwolfach.
Urs Schreiber: CFT, Gerbes and K-Theory in Oberwolfach, IV (August 16, 2005)
Tuesday in Oberwolfach: stacks, gerbes, M-theory and K-theory.
Urs Schreiber: CFT, Gerbes and K-Theory in Oberwolfach, III (August 15, 2005)
Talks on gerbes in WZW models and some other stuff.
Urs Schreiber: CFT, Gerbes and K-Theory in Oberwolfach, II (August 15, 2005)
Monday morning at Oberwolfach: M-theory for mathematicians and 2-gerbes for supergravity.
Urs Schreiber: K-theory for dummies, I (August 12, 2005)
A list of some basic concepts in K-theory.
Urs Schreiber: CFT, Gerbes and K-Theory in Oberwolfach, I (August 12, 2005)
On a workshop in Oberwolfach next week and some details on joint ideas with Igor Bakovic.
Robert H.: Background independence (August 2, 2005)
Last week, Lee Smolin has put a paper on the arxive which on nearly fifty pages does not contain any…
Guest: Non-Commutative Geometry School I (July 27, 2005)
I never meant to say much about this week, but in a completely unexpected turn of events yesterday, Getzler…
Guest: Streetfest Workshop 3 (July 24, 2005)
Let’s start with Katzarkov’s talk on ‘Mirror symmetry and manifolds of general type’. He began with a question: are…
Urs Schreiber: Q: Open Strings in KR Background (July 23, 2005)
How to understand the coupling of the KR field to open strings.
Guest: Streetfest Workshop II (July 22, 2005)
The Streetfest ended yesterday with a talk by Eugenia Cheng on degenerate higher categories and the periodic table of…
Guest: Streetfest Workshop I (July 18, 2005)
Greetings from Canberra! It is very pleasant here. There was a good frost this morning and some black swans…
Urs Schreiber: Costello on Open Topological Strings (July 17, 2005)
On a paper about open topological strings by K. Costello.
Urs Schreiber: Talks in Hamburg, Lectures in Bad Honnef (July 15, 2005)
Random notes on HQFT and BCFT.
Guest: Thursday at the Streetfest III (July 14, 2005)
Gorbunov decided to talk about Gerbes of Chiral Differential Operators instead of what was in his abstract, motivation being…
Guest: Thursday at the Streetfest II (July 14, 2005)
David here I thought I’d talk a bit about Ezra Getzler’s talk (which was only loosely connected to his…
Guest: Thursday at the Streetfest I (July 13, 2005)
Well it’s Thursday morning and I thought I’d say hi now because it’s going to be a very busy…
Guest: Wednesday at the Streetfest IV (July 13, 2005)
Well, I’m going to have dinner with Marnie and David and some other people, but I have a little…
Guest: Wednesday at the Streetfest IV (July 13, 2005)
Well, I’m going to have dinner with Marnie and David and some other people, but I have a little…
Guest: Wednesday at the Streetfest III (July 13, 2005)
Besides Bouwknegt’s talk on D-branes and generalized geometry, which Marnie and David are writing about, and Mueger’s talk on…
Guest: Wednesday at the Streetfest II (July 13, 2005)
Hi - I’ve decided to join in the fun and write a little about Michael Mueger’s talk in the…
Guest: Wednesday at the Streetfest I (July 13, 2005)
Bouwknegt started Wednesday with an apology for not being a category theorist. The main focus of the talk (I…
Guest: Tuesday at the Streetfest III (July 13, 2005)
Where were we. Yes - Bondal on derived categories of toric varieties… Idea 1: for an algebraic variety XX…
Guest: Tuesday at the Streetfest II (July 12, 2005)
Yesterday was a bit of a blur for me - lack of sleep in the previous week catching up,…
Guest: Tuesday at the Streetfest I (July 12, 2005)
Hello again! Wednesday already here. I already have 50 pages of notes. It’s quite overwhelming. Now let’s see. Kapranov…
Guest: Monday at the Streetfest II (July 12, 2005)
David here - I thought I’d mention some of the stuff that went on in the afternoon - a…
Guest: Monday at the Streetfest I (July 11, 2005)
While others report from conferences on Strings or Loops, in Sydney we are enjoying the balmy winter and the…
Urs Schreiber: 2-Holonomy in Terms of 2-Torsors (July 5, 2005)
Details on 2-holonomy in terms of 2-torsors and some pointers to the Streetfest conference.
Urs Schreiber: From Loop Space Mechanics to Nonabelian Strings (June 23, 2005)
My thesis.
Robert H.: Talking to myself (May 26, 2005)
Since nobody answered my question about how to properly generalize the calibration condition for BPS-branes if the gauge field…
Urs Schreiber: String(n), Part II (May 18, 2005)
Review of issues related to String(n).
Urs Schreiber: String(n), Part I (May 18, 2005)
Review of issues related to String(n).
Urs Schreiber: Nonabelian Weak Deligne Hypercohomology (May 17, 2005)
Generalizing Deligne cohomology to the nonabelian and weak case.
Urs Schreiber: PSM and Algebroids, Part V (May 16, 2005)
Transitions in a p-bundle in terms of algebroid morphisms.
Urs Schreiber: 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…
Urs Schreiber: 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.
Urs Schreiber: PSM and Algebroids, Part II (April 29, 2005)
How Courant algebroids gives rise to L_infinity algebras.
Robert H.: Calibrations with gauge field (April 21, 2005)
Assume some closed string background preserving some susy. This comes with at least one Killing spinor whose square can…
Urs Schreiber: Akhmedov comments (April 20, 2005)
More on Akhmedov’s ideas concerning 2D TFTs.
Urs Schreiber: Weak NABG (April 15, 2005)
On weak nonabelian bundle gerbes.
Urs Schreiber: PSM and Algebroids, Part I (April 14, 2005)
There seem to be interesting relations of the Poisson σ\sigma-model (PSM) and of Lie algebroids to all kinds of…
Urs Schreiber: Open topological strings (April 13, 2005)
Some literature on open topological strings.
Robert M.: The arXiv in your pocket. (April 13, 2005)
As pointed out on several other blogs, Joanna Karczmarek has been testing the waters with a downloadable version of the…
Aaron: Susskind on wormholes (April 11, 2005)
Lenny Susskind was recently here and discussed his recent paper on wormholes. As you probably know, he’s mentioned some…
Urs Schreiber: Lessons from low Dimensions (April 9, 2005)
I am currently visting a CFT workshop at University of Bonn, Lessons from low Dimensions - the many Aspects of Conformal Field Theory.
Urs Schreiber: New preprint: From Loop Groups to 2-Groups (and the String Group) (April 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).
Urs Schreiber: 2-NCG: First Refinement (April 1, 2005)
Is 2-NCG an April Fool’s joke?
Urs Schreiber: Akhmedov: Nonabelian 2-Holonomy using TFT (March 31, 2005)
Discussion of Akhmedov’s paper on 2-holonomy.
Urs Schreiber: Derived Categories for Dummies, Part IV (March 22, 2005)
How branes and strings are described by the derived category of coherent sheaves.
Urs Schreiber: Derived Categories for Dummies, Part III (March 20, 2005)
Elementary aspects of derived categories of quiver representations – plus a remark on how this relates to 2-bundles.
Urs Schreiber: Derived Categories for Dummies, Part II (March 19, 2005)
Review of the definition of derived functors.
Urs Schreiber: Rasetti: Quantum Computers based on TQFT (March 19, 2005)
Rasetti proposes that topological quantum field theories may be models for P=NP-quantumcomputers.
Urs Schreiber: Talk at IIASS: Nonabelian Strings (March 16, 2005)
Slides for my talk at the IIASS on nonabelian strings.
Urs Schreiber: Derived categories for dummies, Part I (March 13, 2005)
Some facts about derived categories. And an open question…
Urs Schreiber: Quiver reps and vector 2-bundles (March 11, 2005)
A note on how quiver reps seem to be related to vector 2-bundles as in Baas,Dundas&Rognes.
Urs Schreiber: What’s next (February 24, 2005)
I have just returned from my two week visit of John Baez’s group at UC Riverside, which was extremely nice…
Urs Schreiber: Project: 2-NCG (February 15, 2005)
A discussion of categorified NCG and its relation to superstrings.
Urs Schreiber: Conversation with Kea: Categorified NCG (February 11, 2005)
Conversation with Kea on NCG and categorification.
Robert H.: To baldly go where no man went before (February 10, 2005)
In his reference frame, Lubos reports on a seminar by Reall on higher dimensional black holes and black rings and…
Urs Schreiber: Categorified Gauge Theory and M-Theory (February 9, 2005)
Does categorification of gauge theory know about the dimensions of the fundamental objects in M-theory?
Urs Schreiber: 2-Holonomy LEGO (February 3, 2005)
Category LEGO used to define and discuss global nonabelian 2-holonomy.
Urs Schreiber: New paper: 2-Connections on 2-Bundles (December 30, 2004)
Mine and John Baez’s paper ‘2-connections on 2-bundles’ is available as a preprint.
Urs Schreiber: Re: Categorified Gauge Theory (December 27, 2004)
Comments on how nonabelian surface holonomy relates to nonabelian volume integrals.
Urs Schreiber: Nonabelian Self-Duality (December 15, 2004)
This is a followup to Peter Woit’s recent blog entry Langlands Program and Physics. There, Peter mentions the following…
Urs Schreiber: Re: Category Theory and Physics (December 3, 2004)
Reply to Lubos’s comments on the last entry on categories and strings.
Urs Schreiber: Categorified Points: Strings as Morphisms (November 24, 2004)
Over at sci.math.research there are some comments on categorification and its relation to string theory. Of course categories, being…
Urs Schreiber: Weak groups, hard computation (November 18, 2004)
Results on 2-bundles with coherent structure 2-groups.
Urs Schreiber: Nonabelian gerbes with connection and curving from 2-bundles with 2-holonomy (November 3, 2004)
A proof that a 2-bundle with 2-holonomy defines a nonabelian gerbe with certain connection and curving.
Robert H.: Effective theories and gravity (October 29, 2004)
To rebut fears that having my own blog would let me forget about the coffee table i would like…
Urs Schreiber: Thoughts on n-cube Scaling on 5-Branes (October 27, 2004)
Some thoughts on possible formal reasons for the n-cube scaling of degrees of freedom on 5-branes.
Urs Schreiber: Re: Self-dual strings and M5-brane anomalies (October 22, 2004)
Comment on Lubos’ comment on Berman&Harvey’s Self-Dual String Anomalies.
Urs Schreiber: 2-bundles (October 19, 2004)
Finally there is a paper on 2-bundles.
Urs Schreiber: Tensionless strings and Polyakov’s loops (October 14, 2004)
Aspects of tensionless strings.
Robert M.: Bryce DeWitt (October 3, 2004)
In my last post I didn’t give very many details about the talks at the Quantum Theory of Black…
Robert M.: Finally! (September 19, 2004)
Okay, I’m a bit embarassed but I’ve finally gotten around to contributing something to the String Coffee Table. I’m embarassed…
Urs Schreiber: DDF=Pohlmeyer known in 1981 (September 16, 2004)
Readers of this blog will recall that I was involved in some thinking about Pohlmeyer invariants. It all started with…
Urs Schreiber: States of string in non-abelian 2-form background (September 12, 2004)
Strings in non-abelian 2-form backgrounds again: Some conceptual issues.
Urs Schreiber: r-flatness = 2-associativity (August 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…
Urs Schreiber: News release on emergent string spacetime (August 27, 2004)
My friend Rüdiger Vaas, who is working as a science journalist for the german science magazin Bild der Wissenschaft,…
Urs Schreiber: On loop space and 2-group holonomy (August 27, 2004)
A pdf with my notes on the relation between loop space holonomy and 2-group holonomy is now available.
Urs Schreiber: Why does 2-group theory miss surface holonomies with nonvanishing B+F? (August 24, 2004)
One more observation about the relation between 2-group theory and loop space holonomy.
Urs Schreiber: 1+1D LQG is really about boundary states (August 23, 2004)
What does LQG have to do with boundary states?
Urs Schreiber: Super-Pohlmeyer invariants and boundary states for non-abelian gauge fields (August 20, 2004)
I have just submitted the following to the preprint server: Urs Schreiber: Super-Pohlmeyer invariants and boundary states for non-abelian…
Urs Schreiber: Everybody agrees on the non-abelian boundary state! (August 19, 2004)
I realize that the different definitions of the non-abelian boundary state in the literature all agree.
Urs Schreiber: Microscopic relation between loop space connections and 2-group holonomies (August 18, 2004)
I discuss how loop space holonomies and 2-group holonomies are related.
Urs Schreiber: Escape from the Fog (August 16, 2004)
Report from vacation in Norway - and the inevitable remarks on some string theory.
Urs Schreiber: On Holiday (July 30, 2004)
I’ll be on holiday the next two weeks.
Urs Schreiber: A bird, a plane? No, super-Pohlmeyer! (July 27, 2004)
Recently I had talked about how I think Pohlmeyer invariants are related to boundary states of D-branes with gauge…
Urs Schreiber: More remarks on flat loop space connections (July 23, 2004)
More comments on flat connections on loop space and their relation to surface holonomies.
Urs Schreiber: Three ways to loop flatness (July 22, 2004)
Today I was contacted by Luiz Agostinho Ferreira who kindly called my attention to the paper Orlando Alvarez &…
Urs Schreiber: To loose or not to loose information (July 22, 2004)
Comment on Hawking’s talk on the black hole information loss problem.
Urs Schreiber: Talking to ’t Hooft about tossing TVs (July 19, 2004)
Summary of a talk by ’t Hooft.
Urs Schreiber: Mathematical loop space literature (July 15, 2004)
Readers of my writings will have noticed that I mention the tem loop space from time to time. Now, I…
Urs Schreiber: Nonabelian B-field equations of motion (July 13, 2004)
I try to derive the equations of motion of a nonabelian B-field from boundary state divergences.
Urs Schreiber: Not Abelian - but Flat (July 12, 2004)
The crucial condition for non-abelian 2-form connections is their flatness in loop space.
Urs Schreiber: Scandinavian but not Abelian (July 9, 2004)
I have attended a conference in Karlstad and thought about nonabelian 2-forms.
Urs Schreiber: From Paris to Karlstad (via Bonn) (July 4, 2004)
I am preparing for talks in Bonn and Karlstad.
Urs Schreiber: Cabinet de Curiosites dot com - STRINGS 04 (June 30, 2004)
The annual string theory conference is taking place at College de France in Paris this year. Fortunately this is…
Urs Schreiber: Nonabelian 2-form connection from SCFT deformation (June 21, 2004)
I show how the loop space connection of a nonabelian 2-form arises from the obvious SCFT deformation.
Urs Schreiber: Pohlmeyer invariants and states of the IIB matrix model (June 13, 2004)
Discussion of a relation between Pohlmeyer invariants and distributions of D(-1) branes which solve the IIB matrix model.
Urs Schreiber: Open string backgrounds from boundary state deformations (June 11, 2004)
Review of some aspects of the boundary state deformation technique studied by Koji Hashimoto.
Urs Schreiber: String entropy and black hole correspondence (June 10, 2004)
Brief summary of aspects of the string/black hole correspondence principle.
Urs Schreiber: Experiments probing quantum gravity (June 10, 2004)
List of experiments that try to probe quantum gravity in one way or another.
Urs Schreiber: Sigh. (June 7, 2004)
Bogdanov and Bogdanov have done it again.
Robert H.: Unlooping the LQG string (May 26, 2004)
A report on Thomas Thiemann’s seminar at DAMTP on his quantization of the bosonic string.
Urs Schreiber: CFTs from OSFT! (May 19, 2004)
The relation between classical SFT solutions and (boundary) conformal field theories is further discussed.
Urs Schreiber: 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….
Urs Schreiber: 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.
Urs Schreiber: CFTs from OSFT? (April 29, 2004)
A comment about a relation between string field theory and deformed CFTs on the worldsheet.
Urs Schreiber: Billiards at half-past E10 (April 26, 2004)
Aspects of sigma-models on Kac-Moody groups.
Urs Schreiber: New York, New York (April 23, 2004)
I have visited Ioannis Giannakis in New York, discussing superfconformal deformations.
Urs Schreiber: Power Supply (April 14, 2004)
I am visiting the AEI in Potsdam, discussing Pohlmeyer invariants and issues of quantization of string.
Urs Schreiber: Billiards, random matrices, M-theory and all that (April 8, 2004)
I am currently at a seminar on quantum chaos and related stuff. You cannot enjoy meetings like these without…
Urs Schreiber: Notions of string-localization (March 30, 2004)
Bert Schroer made me aware of the notion of ‘string-localized fields’, which are quite different from ordinary string fields.
Urs Schreiber: Visualization of Superstring States (March 18, 2004)
Heuristic visualization of the massless states of superstring.
Urs Schreiber: DPG Symposium 2004 (March 13, 2004)
I am on my way to the spring conference of the German Physical Society, the Frühjahrstagung der Deutschen Physikalischen Gesellschaft…
Urs Schreiber: Introductory String Theory Seminar (March 11, 2004)
List of introductory literature for string theory.
Urs Schreiber: Poll for sci.physics.strings (March 9, 2004)
Probably everybody has seen the Call for Votes for the creation of a new USENET newsgroup with the proposed…
Urs Schreiber: Simple but not trivial (March 8, 2004)
Discussion of a paper concerned with constant R-R 2-form background in NSR formalism.
Urs Schreiber: Before the flood (March 5, 2004)
On how to approach Type II strings by abstract differential calculus.
Urs Schreiber: [Admin.] How to participate in the String Coffee Table dicussion (February 21, 2004)
A list of tips and tricks for how to participate in the discussion at the String Coffee Table.
Urs Schreiber: The joy of IIB Matrix Models (February 20, 2004)
As readers of sci.physics.research might remember, a while ago I had learned about the IIB Matrix Model and had…
Urs Schreiber: Torsion Gravity from String Theory (February 15, 2004)
I was asked by A. Pelster, who has worked on torsion gravity together with H. Kleinert and F. Hehl,…
Urs Schreiber: [Review] DDF states (January 29, 2004)
The recent discussion about attempts to quantize the (super-)string by studying its algebra of classical invariants (i.e. of phase…
Urs Schreiber: Pohlmeyer charges, DDF states and string-gauge duality (January 29, 2004)
It’s half past two in the morning here in central Europe and a can’t sleep because my brain is thinking…
Urs Schreiber: Thiemann’s quantization of the Nambu-Goto action (January 27, 2004)
Aspects of the recent paper by Th. Thiemann on the ‘LQG-string’ are discussed.
Urs Schreiber: The search for discrete differential geometry (January 26, 2004)
At first it may look like a trivial problem whose solution should have been known for ages, being used…
Urs Schreiber: [Review] Type II on AdS_3, Part I: Lightcone spectrum (January 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.
Urs Schreiber: [Exercise] Canonical analysis of D-string action (January 15, 2004)
The author tries to work his way through the canonical anaylsis of the D-string action. Help him! :-)
Urs Schreiber: Classical deformations of 2d SCFTs - Part II: Algebra Isomorphisms (December 30, 2003)
It has been shown in Part I (see also hep-th/0401175) that the modes of the KK-deformed exterior derivative d…
Urs Schreiber: Classical deformations of 2d SCFTs - Part I: Loop space (December 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 =…
Urs Schreiber: Cosmic F- and D-strings (December 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…
Luboš: Join the stringy discussion on news.groups (December 17, 2003)
Dear Ladies and Gentlemen! A very interesting discussion has been started at news.groups - it is a name of a…
Arvind: Ed’s latest (December 16, 2003)
Ed Witten’s latest: Is weakly coupled (N=4) Yang-Mills-theory also a perturbative string theory? He conjectures that it is, and…
Urs Schreiber: deformation of SCFTs (December 15, 2003)
This environment is very inspiring, I’ll start with a couple of questions right away: :-) Is there anything known about…
Luboš: Thanks to Jacques (December 15, 2003)
It seems that this string coffee table works, because you are able to see this sentence. Thanks to Jacques. So…
Distler: Inaugural Post (December 15, 2003)
Welcome Aaron Bergman, Robert Helling, Lubos Motl, Arvind Rajaraman and Urs Schreiber, and their brand-new blog, The String Coffee…