Welcome to my research portal!

My scientific advances  lie at the intersection of applied mathematics, algebraic & differential geometry, the  phenomenology of vacuum structures & cosmology in string theory,  and computational sciences.

The main focus of my current research is to analyze various model independent aspects of quantum gravity effective field theories to guide towards a deeper understanding of the vacuum structure of our universe.

My current PostDoc affiliation is with the Kavli IPMU, Tokyo university in Japan.

Selected Recent Talks

  • Upcoming:  8. Dec. 2017 – String Theory Workshop, KIAS,  Seoul
  • 7 Sep. 2017 – Seminar at YITP, Stoney Brook University, USA
  • 5 Sep. 2017 – Theory seminar at Cornell University, Ithaca, USA
  • 31 Jul 2017 – Theory seminar at the Max PIanck Institute for Physics in Munich, Germany
  • 6 Jan 2017 – Plenary talk at workshop, theor. Physics dept. Berkeley @ KIPMU week, Berkeley, USA

Research

To evolve a complete understanding of the vacuum structure of our universe one needs to study an ultraviolet complete theory of all interactions thus in particular a theory of quantum gravity. The starting point for such a study is widely believed to be string theory.

My research is devoted to gaining full model independent control of the relevant string length and Kaluza Klein quantum induced corrections to the Wilsonian low energy effective field theories of string theory. The phenomenologically relevant low energy effective theories are four-dimensional supersymmetric theories of gravity and other fields such as scalars, vectors, and fermions. The main focus of those studies concern the Kählerpotential of 4d, N=1 and 3d, N=2 supergravity theories, due to their relevance for phemonemlogy of particle physics and cosmology within string theory.  You may also follow me on HEP-Inspire.  or on Research Gate.

 

2017

  •  The three-dimensional  Kählerpotential, the no-scale structure & the uplift to four dimensions. We will cast light on the elusive correction to the 3d/4d Kählerpotential of our previous work. (to appear)
  • Revising higher-derivative terms in ten & eleven dimensions. We use supersymmetry in four and five dimensions to draw conclusions about the structure of the ten and eleven-dimensional theories. In fact, we encounter novel eight-derivative terms in ten as well as eleven dimensions, which have been overseen in the literature but are necessary for consistency of the theories. view publication

 

2016

  • Revisiting the Euler characteristic correction to the 4d, N=1 Kählerpotential for Calabi-Yau threefolds with an arbitrary number of 4-cycles. I.e. the BBHL correction to the Kählerpotential is recomputed for arbitrary number of Kähler moduli. We explicitly derive the metric background by solving the ten-dimensional modified Einstein equations. The resulting internal six-dimenisonal manifold is no longer Ricci -flat, i.e. is no longer Calabi-Yau.  view publication
  • Novel  four-derivative terms to four-dimensional theories or in other words  string theory induced friction terms for inflation are computed. More concretely, those are four-derivative terms of an arbitrary number of Kähler deformations of Calabi-Yau threefold which couple to the four-dimensional Ricci tensor. Those couplings favour slow role inflation when the role of the  inflaton is played by one of the Kähler moduli.   view publication

 

2015

  • My Ph.D. thesis on geometric corrections to string effective actions. New results include higher-deriviative induced terms of complex structure  deformations of the internal manifold. Those correspond to deformations of 4-cycles of the internal fourfold. Also the imprint of  5-cycle deformations on the effective theory are presented.  view publication
  • The effective action of warped M-theory reductions with higher-derivative terms – Part II .  Following up the previous – Part I – we show that the warp factor in full generality may be integrated into a Kählerpotential. We furthermore, suggest that  the Kähler-coordinates  i.e. the complex structure on the Kähler moduli space needs to be expressed as divisor integrals of the  compactification fourfold. view publication

 

2014

  • The effective action of warped M-theory reductions with higher-derivative terms – Part I. The effective three-dimensional theory including the dynamical imprint of deformations of an arbitrary number of 6-cycles in the internal space is derived. view publication
  • We reexamine M-theory warped fourfold vacua in the presence of higher-curvature terms. The modified Einstein equations @ eight-derivatives are solved explicitly for the  new background metric. The internal space is no longer Calabi-Yau, thus no longer Ricci-flat. Furthermore, we find that the 5th torsion class is non-vanishing.  view publication

     

    2013

    • We analyze the hypothetical uplift – in F-theory – of a novel topological correction from a three-dimensional theory to four dimensions. The previously derived correction in three dimension given by the third Chern form of the internal manifold when naively uplifted to four dimensions simply counts the number of the self intersections of present stacks of D7 branes. view publication
    • We derive a novel  correction to the 3d, N=2 Kählerpotential given by the third Chern form of the internal Calabi-Yau fourfold. Uplifted to four dimensions in the framework of F-theory this results in a leading order alpha prime squared – the fourth power in the string length – correction. view publication

Outreach

My most prominent public outreach

Munich Science Slam 2013 (winner) – A comedian 10 minute play about string theory (TV-broadcast).

 

Representing the Max-Planck society @ Prince of Asturias award 2013. My outreach in this week contained a TV interview about the importance of  international collaborations in science as well as  a TV broadcasted podium discussion about  the same topic. The highlight of the week was  the award ceremony.

Teaching

  • Co-founder of the “ForscherInnen-werkstatt Physik” in 2007, a program where interested high-school scholars of age 12 to 15 could sign up to participate in experiments held at the university of Graz.  I am happy to announce that the “ForscherInnen-werkstatt Physik” had been successfully continued. The experiments were designed analogously to the “Physics Olympiad” programs which exists worldwide, but with a strong focus on hands on experiments.

Computational Physics

The Tensor Calculus Package

The XTensor (xAct) package is an Algebra package for abstract tensor computations in arbitrary dimensions.

The XArus package (currently non-publicly available) was developed independently during the last years, and extends the XTensor package to be applicable on complex manifolds of arbitrary even dimension.

Furthermore, the code allows for non-trivially manipulations of higher-derivative  Lagrangians and E.O.M’s.

One of the most powerful segments is the possibility of generating all Shouten identities and total derivative identities of a given set of higher-derivative operators, as well as Bianchi identities when gravity is involved. This allows to perform non-trivial manipulations of the action. As those analytical identities needed to answer questions relevant in our research can easily grow in the order of thousands we heavily rely on the support of XArus.

Most prominently the package is thus ideal to perform compactifications of higher-derivative supergravity theories relevant in string theory.

Machine Learning – Gravitational Lensing.

Picture deep learning algorithms (AI) are ideal for the search for gravitational lenses, however have been rarely implemented in this context so far. Instead this challenging tasks are mostly performed by conventional algorithms. When a massive object like a galaxy is covering another galaxy in the line of view light bends around the lensing galaxy and becomes thus visible to us. The goal is to try to outsmart conventional algorithms with deep learning image recognition analysis to find many more gravitational lenses in observational images of our universe which have remained undiscovered so far.