Brief CV
Research associate, Humboldt-Universität zu Berlin, GER, 2020–
Research associate, Michigan State University, USA, 2018-2020
Research associate, Technische-Universität München, GER, 2014-2018
Ph.D. in Physics, Johannes Gutenberg-Universität Mainz, GER, 2015
Exchange Student at Tsukuba University, JPN, 2010-2012
Diploma in Physics, Johannes Gutenberg-Universität Mainz, GER, 2008
Teaching activities
Habilitation
Currently, I am pursuing my habilitation, with Hard probes of hot nuclear matter as the topic of the thesis. In the wake of this process, I am heavily engaged in teaching, and have contributed so far to Computations Physics II (Winter 20/21, 21/22, 22/23, 23/24), Computations Physics III (Summer 21), Introduction to Lattice Field Theory (Summer 22, 23, 24), Classical Theoretical Physics (Winter 22/23, 23/24), and Quantum Mechanics (Summer 23, 24). While I have been tutor in most courses, I have recently started to lecture fully independently, and I enjoy this very much.
Mentoring
Since spring/summer 2023 I have been mentoring my first two Bachelor students, Florian Bakenecker and Robert Seibt. Both are working on different aspects of novel lattice fermions. Robert has graduated in winter 2023 with outstanding results, and we aim to publish soon. I also serve as an additional mentor to a few Ph.D students at HU Berlin or at other institutions, i.e. Ilaria Costa within the RTG, Ioannis Trimis at Michigan State University, Sebastian Steinbeißer (now at Leibniz Rechenzentrum, previously at Technische Universität München), Amit Kumar (during his time at Wayne State University).
Summer schools on Methods of Effective Field Theory and Lattice Field Theory
Back in 2016 I have created a new summer school series on Effective Field Theory and Lattice Field Theory together with Nora Brambillat, my PI at Technische Universität München. The first edition in 2017 was held at Garching Forschungszentrum, made possible by funding from VolkswagenStiftung and local support by Leibniz Rechenzentrum. After being forced to virtual operations for the second edition in 2021, we had the third edition in 2023 again as a face-to-face event at Physikzentrum Bad Honnef thanks to the support by Deutsche Physikalische Gesellschaft (DPG). I have contributed as a lecturer already twice. We look forward to a fourth edition in 2026. Please stay tuned!
Research projects
I have been working on a broad range of topics in the Lattice Field Theory group under supervision of Prof. A. Patella. Please see below a summary on some of my research topics. For more details, please have a look at my author profile on Inspire-hep. or on ORCID.
Superstring worldsheet on the lattice: theory and simulations
In the initial GRK proposal we set out to investigate the non-perturbative dynamics of the AdS-superstring using the lattice approach. In this project we have discretized a two-parameter continuum formulation of the gauge-fixed AdS-superstring worldsheet as a two-dimensional non-linear sigma model (NLSM), with four parameters on the lattice such that it respects the global $U(1)\times SU(4)$ symmetry. With the two additional parameters fixed at tree level by demanding the symmetry on the level of 2-point functions, some quantities that we studied at one-loop automatically reproduce the continuum results. Yet this is not sufficient to prove renormalizability and existence of a continuum limit, given the infinite number of diagrams at each loop order.
These models have a sign problem due to the presence of four-fermion operators, which makes the prospects for success with Monte Carlo lattice simulations unclear. We have started to study a somewhat simpler theory with a similar sign problem, namely, the OSP(N+2m|2m)/OSP(N+2m-1|2m) supersphere NLSM. For this model, some analytic results are known from integrability. The fermions of this model violate unitarity and do not to satisfy the spin-statistics theorem. Renormalization of this NLSM is the same as for a more simple O(N) sigma model. We have found a discretization of this model in terms of rescaled boson field variables, removed four-fermion operators with suitable Hubbard-Stratonovich fields, and implemented an Hybrid Monte Carlo algorithm with pseudofermions, Hasenbusch precondtioning and sign reweighting. Results so far indicate a severe sign problem, we have started to explore new algorithms instead of HMC to alleviate it.
To learn more about this project, please visit the AdS/CFT correspondence Research Webpage
Hard probes of hot nuclear matter
The matter content of the visible universe mostly consists of atomic nuclei, whose composition from quarks with gluons as the respective force carriers is described by quantum chromdynamics (QCD). Under extreme conditions such as high temperatures and/or densities, they are liberated from their confinement into nuclei or other hadrons, and instead form a new state matter, the quark-gluon plasma (QGP), which pervades the early universe. Many major experimental facilities (LHC@CERN, RHIC@BNL, FAIR@GSI) have significant parts of their programs dedicated to exploring the properties of QGP by creating primordial fireballs of nuclear matter in heavy-ion collisions (HIC). The only tools that permit probing these fireballs at short distances and early times are hard probes such as heavy quarks, heavy quarkonia, or jets.
As even weakly-coupled hot or dense media at asymptotically high temperatures have non-perturbative properties, it is clear that these must be studied in the lattice approach, in lockstep with tools such as effective field theories (EFT). This is even more true for media of phenomenological interest, i.e. the fireballs in HIC or the neutron stars, which are both known to be strongly-coupled systems. In this context, I have mostly contributed on the lattice side to studies of in-medium bottomonia, both relativistic or in the static limit, probes of thermal dissociation and chromoelectric screening, heavy quark diffusion, and jet transport on the LGT side. I am taking a closer look at the influence of heavy quarks in the sea, i.e. the charm contribution to the equation of state or to the static potential, and to pseudoscalar charmed meson correlator’s time moments as a probe to measure the strong coupling and charm mass. Finally, I am also engaging in more phenomenological approaches in this context. Together, these different results for in-medium hard probes coherently suggest that the perturbative hard thermal loop approach is inadequate, which still informs many dynamical models; thus, our results might eventually trigger some rethinking in HIC phenonenology.
To learn more about this project, pleas visit the Inspire-hep profiles of the TUMQCD and
HotQCD collaborations, which I am most aligned with.
Novel lattice fermions
I have been very active for many years in the search for novel lattice fermion actions. These may help extend the accessible range of LGT at finite density, that is affected by an np-hard sign problem, and requires a rethinking the lattice approach. I have demonstrated that minimally doubled fermions, a technique that I have pioneered in simulations during my doctorate, correctly perceive topology of a gauge field background in two dimensions. My expertise in this area is unique and recognized across the global LGT community, and I do my best to share this fascination with young students as a pathway to access the beauty and intricacies of lattice field theory. I have submitted a proposal Toward practical application of Minimally Doubled Fermion actions for QCD matter for the Heisenberg program of DFG in December 2023.
To learn more about this project, please visit the website of our recent workshop at Novel Lattice Fermions and their Suitability for High-Performance Computing and Perturbation Theory