Welcome!
I am a postdoctoral researcher at the Leibniz University of Hannover's physics department. In 2017, I have finished my PhD at the University of Regensburg's math department.
My areas of specialization are mathematical physics and calculus of variations. Furthermore, I am interested in foundational physics, in particular in:
 The Theory of Causal Fermion Systems (Wiki, Introductory Article, Recording of Spring School)
 Foundations of Quantum Theory
 Mathematical Physics
 Aspects of General Relativity
Upcoming events:


Other events which I have coorganized.
Publications:
6.) A Class of Conserved Surface Layer Integrals for Causal Variational Principles
Felix Finster, Johannes Kleiner arXiv:1801.087155.) Dynamics of Causal Fermion Systems  Field Equations and Correction Terms for a New Unified Physical Theory (PhD Thesis)
University of Regensburg urn:nbn:de:bvb:355epub362894
I gratefully acknowledge the support of the Studienstiftung des Deutschen Volkes.4.) A Hamiltonian Formulation of Causal Variational Principles
Felix Finster, Johannes Kleiner arXiv:1612.07192 J. Calc. Var. (2017) 56:733.) Quantum Mathematical Physics (Birkhäuser 2015)
Eds. Felix Finster, Johannes Kleiner, Christian Röken, Jürgen Tolksdorf ISBN 97833192690232.) NoetherLike Theorems for Causal Variational Principles
Felix Finster, Johannes Kleiner arXiv:1506.09076 J. Calc. Var. (2016) 55:351.) Causal Fermion Systems as a Candidate for a Unified Physical Theory
Felix Finster, Johannes Kleiner arXiv:1502.03587 2015 J. Phys.: Conf. Ser. 626 012020
Vita:
Here is my scientific CV. Also, I am involved in the Campus Asyl mentoring program for refugees, the Studienstiftung/DAAD program an(ge)kommen and the Basic Research Community for Physics e.V.
Miscellanea:
The following video explains the Theory of Causal Fermion Systems to a general audience in German:
Talks:
30.) Dynamics of Causal Fermion Systems (PhD Defence, Colloquium of Department for Mathematics, Regensburg University, September 2017)
29.) Correction Terms for Field Equations from Causal Fermion Systems (Working Seminar Mathematical Physics, Regensburg University, July 2017)
28.) La cuisine différente. Impressions from a new approach to fundamental physics (Quantum Lunch Seminar, University of Oxford, June 2017)
27.) Causal Variational Principles (PDE CDT Student Seminar, University of Oxford, June 2017)
26.) Causal Fermion Systems as a Candidate for a Unified Physical Theory (Lobster Lunch Seminar, University of Oxford, May 2017)
25.) Reductionism, ad absurdum? (Rethinking Foundations of Physics Workshop 2017, Dorfgastein, Austria, March 2017)
24.) Naked Singularities and the Penrose Inequality II (Working Seminar Mathematical Physics, Regensburg University, January 2017)
23.) Naked Singularities and the Penrose Inequality I (Working Seminar Mathematical Physics, Regensburg University, December 2016)
22.) Hamiltonian Time Evolution for Causal Variational Priciples (McGill University, Montreal, Canada, November 2016)
21.) Hamiltonian Time Evolution for Causal Variational Priciples (Harvard CMSA Members' Seminar, USA, September 2016)
20.) A New Candidate for a Unified Physical Theory (Harvard CMSA Mathematical Physics Seminar, USA, September 2016)
19.) Towards a Connection between Loop Quantum Gravity and Causal Fermion Systems (Working Seminar Mathematical Physics, University of Regensburg, Germany 2016)
18.) Spring School on Causal Fermion Systems (Regensburg, Germany, March 2016, Link)
17.) The jet bundle dynamics of causal fermion systems (Seminar Partial Differential Equations on Globally Hyperbolic Spacetimes and Working Seminar Mathematical Physics, Regensburg, October 2015)
16.) Physik und Transzendenz (Doktorandentagung Studienstiftung des deutschen Volkes, Bonn, November 2015)
15.) NoetherLike Theorems for Causal Variational Principles (Seminar Partial Differential Equations on Globally Hyperbolic Spacetimes and Working Seminar Mathematical Physics, Regensburg, October 2015)
14.) Causal Fermion Systems as a Candidate for a Unified Physical Theory (Conference "Quantum Theory: from foundations to technologies", Växjö, Sweden)
13.) Noetherlike theorems for causal variational principles (Working Seminar Mathematical Physics, Regensburg, June 2015)
12.) Imre Lakatos' Conception of Science (Doktorandentagung Studienstiftung des deutschen Volkes, Heidelberg, April 2015)
11.) Physik und Transzendenz (A series of three talks: "Albert Einstein  Naturwissenschaft und Religion", "Arthur Eddington  Wissenschaft und Mystizismus", "Carl Friedrich von Weizsäcker  Naturgesetz und Theodizee", based on essays of the three scientists which carry the same name as the talk; Neupfarrkirche Regensburg, October + November 2014)
10.) Causal fermion systems: a dynamical collapse theory? (Workshop DICE2014, Castiglioncello Italy, September 2014)
9.) Introduction to the theory of causal fermion systems (Oberseminar Mathematische Physik, LMU Munich, July 2014)
8.) QT and GR united? An introduction to causal fermion systems (Conference "Quantum Roundabout", Nottingham GB, July 2014)
7.) Paradigms of Modern Physics and Causal Fermion Systems (Series "Zurück zu den Zusammenhängen", Erlangen, April 2014)
6.) QT and GR united? A review of causal fermion systems (Working Seminar Mathematical Physics, Regensburg, May 2014)
5.) QT, QFT and GR united? Causal Fermion Systems: idea and paradigms behind (Paradigms of Modern Physics Workshop, Dorfgastein, March 2014)
4.) Mass and momentum of asymptotically flat manifolds (Seminar Recent mathematical progress in General Relativity, Regensburg, September 2013)
3.) The measurement problem in linear (quantum) theories (Working Seminar Mathematical Physics, Regensburg, May 2013)
2.) Locality in quantum theory (Philosophy of Quantum Theory Cabin Workshop, Hammerlochhäusle, March 2013)
1.) Experimental Status of Foundations of Gravity (Seminar Modern Experiments in Special and General Relativity, Heidelberg, 2012)
Last but not least:
My public email address: contact@jkleiner.de. My public PGP key. (What is PGP?) Further contact info here.