External links to my publications:

Below is a complete list of my writings.


  1. A representation of the string 2-group
    together with Peter Kristel, Matthias Ludewig, August 2023
  2. Lie 2-groups from loop group extensions
    together with Matthias Ludewig, March 2023
  3. The stringor bundle
    together with Peter Kristel, Matthias Ludewig, June 2022
  4. The insidious bicategory of algebra bundles
    together with Peter Kristel, Matthias Ludewig, April 2022
  5. Categorical symmetries of T-duality
    February 2022
  6. 2-vector bundles
    together with Peter Kristel, Matthias Ludewig, June 2021
  7. Connes fusion of spinors on loop space
    together with Peter Kristel, December 2020

Preprints accepted for publication

  1. Geometric T-duality: Buscher rules in general topology
    Ann. Henri Poincaré, to appear
  2. Pontrjagin duality on multiplicative Gerbes
    together with Jaider Blanco, Bernardo Uribe
    J. Noncommut. Geom., to appear
  3. Observation of multi-skyrmion objects created by size and density control in Ta/CoFeB/MgO films
    together with Christian Denker, Hauke Lars Heyen, Yannik Junk, Enno Lage, Jeffrey McCord, Markus Münzenberg, Sören Nielsen, Malte Römer-Stumm, Jakob Walowski
    Journal of Physics D, to appear
  4. Smooth Fock bundles, and spinor bundles on loop space
    together with Peter Kristel
    J. Diff. Geom., to appear

Journal articles

  1. Smooth Functorial Field Theories from B-Fields and D-Branes , together with Severin Bunk
    J. Homotopy Relat. Struct. 16.1 (2021): 75-153  arxiv:1911.09990  
  2. Fusion of implementers for spinors on the circle , together with Peter Kristel
    Adv. Math. Vol. 402 (2022), 108325  arxiv:1905.00222  
  3. Transgression of D-branes , together with Severin Bunk
    Adv. Theor. Math. Phys., Vol. 25, No. 5 (2021), pp. 1095-1198.  arxiv:1808.04894  
  4. Higher geometry for non-geometric T-duals , together with Thomas Nikolaus
    Commun. Math. Phys. 374, 317–366(2020)  arxiv:1804.00677  
  5. Parallel transport in principal 2-bundles 
    Higher Structures 2(1):57-115, 2018  arxiv:1704.08542  
  6. A global perspective to connections on principal 2-bundles 
    Forum Math. 30 (2017), no. 4, 809-843  arxiv:1608.00401  
  7. Transgressive loop group extensions 
    Math. Z. 286(1) 325-360, 2017  arxiv:1502.05089  
  8. String geometry vs. spin geometry on loop spaces 
    J. Geom. Phys. 97 (2015), 190-226  arxiv:1403.5656  
  9. Local Theory for 2-Functors on Path 2-Groupoids , together with Urs Schreiber
    J. Homotopy Relat. Struct. (2016) 1-42  arxiv:1303.4663  
  10. Spin structures on loop spaces that characterize string manifolds 
    Algebr. Geom. Topol. 16 (2016) 675–709  arxiv:1209.1731  
  11. The gauging of two-dimensional bosonic sigma models on world-sheets with defects , together with Krzysztof Gawedzki, Rafal R. Suszek
    Rev. Math. Phys 25 (2013) 1350010  arxiv:1202.5808  
  12. Lifting Problems and Transgression for Non-Abelian Gerbes , together with Thomas Nikolaus
    Adv. Math. 242 (2013) 50-79  arxiv:1112.4702  
  13. Transgression to Loop Spaces and its Inverse, III: Gerbes and Thin Fusion Bundles 
    Adv. Math. 231 (2012), 3445-3472  arxiv:1109.0480  
  14. Four Equivalent Versions of Non-Abelian Gerbes , together with Thomas Nikolaus
    Pacific J. Math., 264-2 (2013), 355-420  arxiv:1103.4815  
  15. Transgression to Loop Spaces and its Inverse, II: Gerbes and Fusion Bundles with Connection 
    Asian J. Math., Vol. 20, No. 1 (2016), pp. 59-116  arxiv:1004.0031  
  16. Global Gauge Anomalies in two-dimensional Bosonic Sigma Models , together with Krzysztof Gawedzki, Rafal R. Suszek
    Commun. Math. Phys. 302 (2), 513-580 (2011)  arxiv:1003.4154  
  17. Transgression to Loop Spaces and its Inverse, I: Diffeological Bundles and Fusion Maps 
    Cah. Topol. Géom. Différ. Catég., 2012, Vol. LIII, 162-210  arxiv:0911.3212  
  18. Polyakov-Wiegmann Formula and Multiplicative Gerbes , together with Krzysztof Gawedzki
    J. High Energy Phys. 09 (2009) 073  arxiv:0908.1130  
  19. String Connections and Chern-Simons Theory 
    Trans. Amer. Math. Soc. 365 (2013), 4393-4432  arxiv:0906.0117  
  20. Bundle Gerbes for Orientifold Sigma Models , together with Krzysztof Gawedzki, Rafal R. Suszek
    Adv. Theor. Math. Phys. 15 (3), 621-688 (2011)  arxiv:0809.5125  
  21. Connections on non-abelian Gerbes and their Holonomy , together with Urs Schreiber
    Theory Appl. Categ., Vol. 28, 2013, No. 17, pp 476-540  arxiv:0808.1923  
  22. Multiplicative Bundle Gerbes with Connection 
    Differential Geom. Appl. 28(3), 313-340 (2010)  arxiv:0804.4835  
  23. Smooth Functors vs. Differential Forms , together with Urs Schreiber
    Homology, Homotopy Appl., 13(1), 143-203 (2011)  arxiv:0802.0663  
  24. Parallel Transport and Functors , together with Urs Schreiber
    J. Homotopy Relat. Struct. 4, 187-244 (2009)  arxiv:0705.0452  
  25. Bi-branes: Target Space Geometry for World Sheet topological Defects , together with Jürgen Fuchs, Christoph Schweigert
    J. Geom. Phys. 58(5), 576-598 (2008)  arxiv:hep-th/0703145  
  26. More Morphisms between Bundle Gerbes 
    Theory Appl. Categ. 18(9), 240-273 (2007)  arxiv:math/0702652  
  27. WZW Orientifolds and finite Group Cohomology , together with Krzysztof Gawedzki, Rafal R. Suszek
    Commun. Math. Phys. 284(1), 1–49 (2007)  arxiv:hep-th/0701071  
  28. Unoriented WZW Models and Holonomy of Bundle Gerbes , together with Urs Schreiber, Christoph Schweigert
    Commun. Math. Phys. 274(1), 31–64 (2007)  arxiv:hep-th/0512283  


  1. A Construction of String 2-Group Models using a Transgression-Regression Technique 
    Analysis, Geometry and Quantum Field Theory, edited by C. L. Aldana, M. Braverman, B. Iochum, and C. Neira-Jiménez, volume 584 of Contemp. Math., pages 99-115, AMS, 2012  arxiv:1201.5052  
  2. A Loop Space Formulation for Geometric Lifting Problems 
    J. Aust. Math. Soc. 90, 129-144 (2011)  arxiv:1007.5373  
  3. Bundle Gerbes and Surface Holonomy , together with Jürgen Fuchs, Thomas Nikolaus, Christoph Schweigert
    Proceedings of the 5th European Congress of Mathematics, edited by A. Ran, H. te Riele and J. Wiegerinck, EMS Publishing House, 2008, 167-197  arxiv:0901.2085  

Book contributions

  1. Non-abelian gerbes and some applications in string theory  , together with Christoph Schweigert
    Particles, Strings and the Early Universe : The Structure of Matter and Space-Time, edited by J. Haller and M. Grefe, Verlag Deutsches Elektronen-Synchrotron, 2018  arxiv:1807.05398  
  2. Gerbes and Lie Groups , together with Christoph Schweigert
    Developments and Trends in Infinite-Dimensional Lie Theory, edited by K.-H. Neeb and A. Pianzola, volume 600 of Progr. Math., Birkhäuser, 2010  arxiv:0710.5467  
  3. Surface Holonomy 
    Handbook of pseudo-Riemannian Geometry and Supersymmetry, edited by V. Cortés, IRMA Lectures in Mathematics and Theoretical Physics, EMS Publishing House, 2008  pdf file  


  • Algebraic Structures for Bundle Gerbes and the Wess-Zumino Term in Conformal Field Theory
    PhD thesis, Universität Hamburg, December 2007
    pdf file  
  • The 2-Category of Bundle Gerbes
    Diploma thesis, Universität Hamburg, September 2006
    pdf file  
  • Holonomie von Gerben im Wess-Zumino-Witten-Modell
    Diploma thesis, RWTH Aachen, November 2004
    pdf file