Academic Work...

Recent Research:

My research work is focused on F-theory GUT model building (a branch of non-perturbative string theory), following the developments in this area since its “minirevolution” in early 2008. From a very conservative perspective F-theory is just a geometric interpretation and different description of Type-IIB superstring vacua, where two non-trivial background fields parameterize a potentially singular torus at each point of the ten-dimensional space-time. However, a proper treatment actually reveals a much more intricate structure. Many non-perturbative “artificial” ingredients of the perturbative Type-IIB string theory have an unified and elegant description in terms of F-theory. Therefore, in another light, F-theory GUT model building actually goes right into the direction of Einstein’s final dream of a complete geometrization of all of known forces and matter constituents, which makes this subject all the more interesting to me...

Contributions:

After some early failed attempts to get a better understanding of the relationship between F-theory and IIB-orientifolds based on (p,q) 7-branes and ABC-brane collections, finally some work in this direction was completed. The work revealed a number of more or less surprising restrictions on the gauge group one can obtain in global F-theory models obtained from simple IIB uplifts. In a more involved investigation of the model building properties, the usage of the spectral cover description of the gauge flux allowed us to provide further details on the phenomenological issues in global F-theory GUT model building. In particular, we were able to find a rather simple global model having three chiral matter generations as an explicit example. In our next project we considered the uplift of D3-brane instantons in IIB-orientifolds with their supposed uplift counterparts, the M5-brane instantons. Parallel to this project, we also investigated a new algorithm for computing the sheaf cohomology of line bundles on toric varieties, a task which appeared more and more often in our work. Considerable time was spend on a suitable implementation and subsequent questions arising from this project. to be continued...

I’ve written an elementary introduction into the subject of string theory and F-theory in case you want to know more.

Academic background:

Chronicles enroute to a PhD:

My PhD time at the Max-Planck-Institute of Physics in Munich started in May 2008. A few months later in early October 2008 I went to the first conference as part of the Munich group at the Erwin-Schrödinger-Insititut in Vienna, Austria, which focused on mathematical aspects of string phenomenology and model building. Right after the christmas holidays I followed an invitation from a former colleague from Bielefeld: Aleksander Rakic, who had moved to Würzburg for his first post-doctoral work, asked me to give an overview talk on string theory and recent developments as part of their weekly graduate seminar. My second external trip was to a 3-day-workshop at the DESY in Hamburg on string-related GUT model building in early February. A week of June 2009 I spend in the capital of Poland—Warsaw—attending the String Phenomenology 2009 conference. In late July together with the other PhD and diploma students of the MPI I stayed a week at Castle Ringberg for the annual IMPRS Young Scientists Workshop in order to exchange ideas in a relaxed environment. From March to April 2010 I had the distinct pleasure of spending an entire month at the KITP in Santa Barbara, California as an affiliate participant of the 10-week “Strings at the LHC and in the Early Universe” program. to be continued...

Physics in Bielefeld:

In July 2007, I finished my first diploma in theoretical physics (in German called “Diplomarbeit”, internationally comparable with a M.Sc.) entitled Semi-Realistic Orbifold Compactification of Heterotic Strings under the supervision of R. Kögerler. For the thesis I reviewed the different classical methods of space-time compactification, particularly Calabi-Yau and orbifold compactifications of the E8xE8-heterotic string, which in recent years yielded semi-realistic effective 4-dimensional theories that are quite comparable with the Standard Model. Rather large portions of the text focused on the mathematical background of spinors and bundles, which are relevant to fully understand the requirement of minimal supersymmetry in the resulting effective theories.

It was due to rather furtunate circumstances that I could work on this topic, considering the fact that there is no reseach group on string theory in Bielefeld. The idea for a mathematically flavored thesis did arise in the aftermath of a joined seminar between the theoretical physics and mathematics department, which was held back in the summer semester 2006 (if I remember correctly). My later physics’ advisor Prof. Kögerler proposed to write a concise (compared to the avaiblable literature) but mathematical rather accurate summary of orbifold compactification. While reading into the subject of string theory (which I essentially had to learn exclusively from the literature) I developed a great interest in the Calabi-Yau compactification process, as one needs far more advanced (i.e. interesting) mathematical tools to access the relevant topological and geometrical information of those particular spaces. However, this required a thorough understanding of spinor geometry, which ultimately resulted in the thesis as presented above.

A month earlier, from 25th to 29th of June 2007, I went to the large international Strings 2007 conference held at the Universidad Autonoma / Cantoblanco in Madrid (Spain), where quite a number of interesting new results were presented from speakers all over the world. Back at that time, it was a rather odd experience—I did not know anyone from the community which naturally isolates somewhat—but which also paved the way of my further studies in an important manner: I met my later PhD advisor R. Blumenhagen back there for the first time. Therefore I like to remember this conference as one of the main cornerstones along my academic road. After an apparently well-received 15-minute presentation talk (slides here) following an official application in the IMPRS program I choose Munich to pursue my PhD. However, this put quite a time pressure on my second main interest...

Mathematics on the sidetrack:

During the last days of April 2008 I completed my second diploma in pure mathematics. In the thesis—called Dimensional Reduction of Spin(7)-Instantons and supervised by K. A. Frøyshov—I considered certain generalizations of classical 4d gauge instantons to higher dimensions, using certain 8-dimensional base spaces with the reduced holonomy group Spin(7). The available general methods are then applied in two particular examples.

Due to my background in theoretical physics and my interest in geometry and topology, my advisor suggested this particular topic as work suitable for a diploma thesis. In the aftermath, certain steps proved to be very straineous, but I certainly learned quite a lot from reading into the subject. However, as I’ve mentioned in the thesis’ acknowledgement, I feel that the thesis was released premature—there are a number of fine points that I would have liked to improve, but the deadline to the beginning of my PhD work at the MPI in Munich was rather restrictive.