# about me

I am a postdoc at the theory group of Nikhef, Amsterdam. My field of research is *mathematical physics*.

In my research, I deal with the mathematical structures of *quantum field theories*. These theories describe the behaviour of matter at the fundamental level. The emerging structures have many surprising connections to problems from mathematics. Kevin Hartnett wrote an article about some of these connections for a general audience.

Before coming to Amsterdam, I did my PhD student in Dirk Kreimer's group at Humboldt-Universität zu Berlin.

Download my CV.

### Contact

firstname.surname@nikhef.nl

### Publications

#### Preprints

The Euler characteristic of Out(F

_{n}), preprint July 2019with Karen Vogtmann - accepted for publication in Commentarii Mathematici Helvetici

#### Journal articles

The Hopf algebra structure of the R

^{∗}-operation,*Journal of High Energy Physics*, Article 61, July 2020 (arXiv)with Robert Beekveldt and Franz Herzog

Non-Perturbative Completion of Hopf-Algebraic Dyson-Schwinger Equations,

*Nuclear Physics B*, Volume 957, August 2020, 115096 (arXiv)with Gerald V. Dunne

Renormalized asymptotic enumeration of Feynman diagrams,

*Annals of Physics*, Volume 385, October 2017, Pages 95-135 (arXiv)

Generating asymptotics for factorially divergent sequences,

*Electronic Journal of Combinatorics*, Volume 25, Issue 4, October 2018, P4.1 (arXiv)The results of this article are summarized in this colorful poster for FPSAC 2017.

Algebraic lattices in QFT renormalization,

*Letters in Mathematical Physics*, Volume 106, Issue 7, July 2016, Pages 879-911 (arXiv).Feynman graph generation and calculations in the Hopf algebra of Feynman graphs,

*Computer Physics Communications*, Volume 185, Issue 12, December 2014, Pages 3317-3330 (arXiv):Information and downloads to the two programs

*feyngen*and*feyncop*is available on this page.

#### Proceedings

Generating Asymptotics for factorially divergent sequences,

*Séminaire Lotharingien de Combinatoire*, 78B.28 (2017), 12 pp.Proceedings contribution for FPSAC 2017.

Feynman diagrams and their algebraic lattices,

*Resurgence, Physics and Numbers*CRM Series - Edizioni della Normale, Volume 20, 2017, Pages 91-107 (arXiv)with Dirk Kreimer: Proceedings contribution for Resurgence, Physics and Numbers.

Computations and generation of elements on the Hopf algebra of Feynman graphs,

*Proceedings of 16th International workshop on Advanced Computing and Analysis Techniques in physics research (ACAT)*, J. Phys.: Conf. Ser. 608, 2015 (arXiv)Proceedings contribution for ACAT 2014.

#### Other

Graphs in perturbation theory: Algebraic structure and asymptotics, May 2018 (arXiv):

My PhD thesis - available as hardcover in the Springer Theses series (amazon)

Algorithmization of the Hopf algebra of Feynman graphs, August 2013:

My master's thesis

### Science outreach

Winter 2018, Berlin:

Appearance on the podcast Neues Berlin, where I was interviewed about the implications of quantum mechanics

### Teaching

Summer term 2019

Field Theory in Particle Physics at the Universiteit van Amsterdam: I assisted Eric Laenen, Wouter Waalewijn, Bernard de Wit teaching their course on particle physics

Winter and Summer terms 2016/2017

Interdiscplinary research seminar on Eynard-Oratin Topological recursion at the Humboldt-Universität Berlin Campus Nord

Winter and Summer terms 2015/2016

Interdiscplinary research seminar on Infrared and collinear divergences in perturbative QFT at the Humboldt-Universität Berlin Campus Nord

### Research stays

University of Waterloo - Combinatorics and Optimization Department, Waterloo - Canada, May 2018

Visitor in Karen Yeat's group, which works on combinatorics in quantum field theory.

Erwin Schrödinger International Institute for Mathematics and Physics, Vienna - Austria, October 2017

Participant in the Programme Algorithmic and Enumerative Combinatorics.

University of Waterloo - Combinatorics and Optimization Department, Waterloo - Canada, March 2017

Visitor in Karen Yeat's group, which works on combinatorics in quantum field theory.

Radboud University Nijmegen - IMAPP, Nijmegen - Netherlands, November 2013 - January 2014

Visitor in Walter van Suijlekom's group, where we studied BRST symmetries and associated cohomologies in matrix models.

CERN, Geneva - Switzerland, June - September 2012

In the scope of the CERN Summer Student Programme, I programmed tools to facilitate high energy physics data analysis under the supervision of Lorenzo Moneta.

### Invited talks

#### 2019/2020

~~Graph Complexes and Quantum Field Theory, Berlin - Germany, 21-25 September 2020~~~~Talk on 'Out(F_n), M_gn and renormalized topological field theory'~~*(postponed due to SARS-CoV-2)*Topology Seminar, Karlsruhe - Germany, 02 July 2020

Talk on 'The Euler characteristic of Out(Fn) and renormalized topological field theory'

*(online talk)*Structure of Local Quantum Field Theories, Berlin - Germany, 04 May 2020

Talk on 'Fast Feynman parametric integral evaluation via tropical sampling'

*(online talk)*~~Resurgence in string and gauge theory, AIM - San Jose - US, 05 Mai 2020~~~~Talk on 'The ring of factorially divergent power series and its applications'~~*(canceled due to SARS-CoV-2)*~~Algebraic Structures in Perturbative Quantum Field Theory, IHES - Paris - France, 30 March 2020~~~~Talk on 'The Hopf algebra structure of the R* operation'~~*(postponed due to SARS-CoV-2)*Theoretical Physics Seminar, Liverpool - UK, 26 February 2020

Talk on 'Graphical functions applied to phi^3 in D = 6' (slides)

Emmy-Noether-Seminar, Erlangen - Germany, 7 February 2020

Talk on 'The Euler characteristic of Out(F_n)' (slides)

Geometry Seminar, Nijmegen - Netherlands, 28 January 2020

Talk on 'Renormalized topological field theory and the Euler characteristic of Out(F_n)' (slides)

Algebraic Combinatorics Seminar, Waterloo - Canada, 12 December 2019

Talk on 'Out(F_n), M_gn and renormalized topological field theory'

Canadian Mathematical Society Winter Meeting, Toronto - Canada, 9 December 2019

Talk on 'Constrained Graph Counting' (slides)

Theory Seminar of the Max-Planck-Institute, Munich - Germany, 4 December 2019

Talk on 'Efficient Monte-Carlo on Feynman parametric integrals'

Combinatorics Seminar, Vienna - Austria, 21 November 2019

Talk on 'Renormalized topological field theory'

Mathematical Physics Seminar, Vienna - Austria, 19 November 2019

Talk on 'The graphical function method applied to phi^3 in D=6' (slides)

Topology Seminar, Oxford - UK, 4 November 2019

Talk on 'The Euler characteristic of Out(Fn) and renormalized topological field theory'

Emmy-Noether-Seminar, Erlangen - Germany, 18 September 2019

Talk on 'The graphical function method in 2n-dimensions' (slides)

RADCOR 2019, Avignon - France, 12 September 2019

Talk on 'Systematic integration of higher loop gauge theory amplitudes in position space' (slides)

#### 2018/2019

Structure of Local Quantum Field Theories, Berlin - Germany, 28 Januar 2019

Talk on 'The Euler characteristic of OutFn'

Emmy-Noether-Seminar, Erlangen - Germany, 16 November 2018

Talk on 'Deriving asymptotics for factorially divergent power series'

Higgs as Probe and Portal Meeting, Amsterdam - Netherlands, 21 September 2018

Talk on 'Asymptotics and algebraic structure in perturbation theory'

#### 2017/2018

Summer school on structures in local quantum field theory, Les Houches - France, 4 - 15 June 2018

Talk on 'Graphs in Perturbation Theory' (slides)

Combinatorial structures in perturbative QFT, Waterloo - Canada, 25 May 2018

Talk on 'Counting graphs without given edge-induced subgraphs' (slides)

University of Waterloo: Algebraic Combinatorics Seminar, Waterloo - Canada, 10 May 2018

Talk on 'Hopf algebra of graphs for restricted graphical enumeration'

Workshop on Enumerative Combinatorics, Vienna - Austria, 16 - 20 October, 2017

Talk on 'Hopf algebras and factorial divergent power series: Algebraic tools for graphical enumeration' (slides)

ALEA in Europe, Vienna - Austria, 9 - 13 October, 2017

Talk on 'Generating Asymptotics for factorially divergent sequences' (slides)

#### 2016/2017

Formal Power Series and Algebraic Combinatorics (FPSAC), London - United Kingdom, 9 - 13 July, 2017

Poster about 'Generating Asymptotics for factorially divergent sequences'

Proceedings contribution: Generating Asymptotics for factorially divergent sequences,

*Séminaire Lotharingien de Combinatoire*, 78B.28 (2017), 12 pp.Algebraic Combinatorics, Resurgence, Moulds and Applications (CARMA), Luminy - France, 26 - 30 June, 2017

Talk on 'Flag decompositions of graphs and their Hopf algebraic structure'

International school of subnuclear physics, Erice - Italy, 14 - 23 June 2017

Talk on 'Bounds and estimates for Feynman-perturbative expansions' (slides)

University of Waterloo: Algebraic Combinatorics Seminar, Waterloo - Canada, 30 March 2017

Talk on 'Zero-dimensional quantum field theory or counting classes of graphs using Gaussian integrals and Hopf algebras'

#### 2015/2016

Resurgence in Gauge and String Theories, Lisbon - Portugal, 18 - 22 July 2016

Talk on 'Asymptotic Calculus for Combinatorial Dyson-Schwinger Equations' (slides)

Kolleg Mathematik Physik Berlin (KMPB-Day), Berlin - Germany, 20 June 2016

Talk on 'Factorially divergent expansions from a QFT perspective'

Combinatorial Structures in Perturbative Quantum Field Theory, Vancouver - Canada, 21 March 2016

Talk on 'Generating functions' asymptotics' generating functions' (slides)

Paths to, from and in renormalisation, Potsdam - Germany, 8 - 12 February 2016

Talk on 'Asymptotic expansions and combinatorial Dyson-Schwinger equations' (slides)

#### 2014/2015

Resurgence, Physics and Numbers, Pisa - Italy, 18 - 22 May 2015

Talk on 'Combinatorics of Feynman diagrams and the algebraic lattice structure in QFT' (slides)

Proceedings contribution with Dirk Kreimer: Feynman diagrams and their algebraic lattices,

*Resurgence, Physics and Numbers*CRM Series - Edizioni della Normale, Volume 20, 2017, Pages 91-107 (arXiv)

Dyson-Schwinger Equations in Modern Mathematics & Physics, Trento - Italy, 22 - 26 September 2014

Talk on 'The Hopf-Algebra of Feynman graphs as the foundation of Dyson-Schwinger equations'

Parallel session - Track 3, 16th International workshop on Advanced Computing and Analysis Techniques in physics research (ACAT), Prague - Czech Republic, 1 - 5 September 2014

Talk on 'Computations and generation of elements on the Hopf algebra of Feynman graphs'

Proceedings contribution: Computations and generation of elements on the Hopf algebra of Feynman graphs,

*Proceedings of 16th International workshop on Advanced Computing and Analysis Techniques in physics research (ACAT)*, J. Phys.: Conf. Ser. 608, 2015 (arXiv).

#### 2013/2014

Summer school on structures in local quantum field theory, Les Houches - France, 9 - 20 June 2014

Talk on 'The Hopf algebra of Feynman graphs as foundation for Dyson Schwinger equations'

#### 2012/2013

CERN Summer Student Lecture Programme, CERN - Switzerland, Summer 2012