Results for "Jakob Böker"

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Quasiparticle Interference and Symmetry of Superconducting Order Parameter in Strongly Electron-Doped Iron-based SuperconductorsMar 14 2019Motivated by recent experimental reports of significant spin-orbit coupling (SOC) and a sign-changing order-parameter in the Li$_{1-x}$Fe$_x$(OHFe)$_{1-y}$Zn$_y$Se superconductor with only electron pockets present, we study the possible Cooper-pairing ... More
Stellar populations and star formation histories of the nuclear star clusters in six nearby galaxiesJul 23 2018The majority of spiral and elliptical galaxies in the Universe host very dense and compact stellar systems at their centres known as nuclear star clusters (NSCs). In this work we study the stellar populations and star formation histories (SFH) of the ... More
Color Refinement, Homomorphisms, and HypergraphsMar 29 2019Recent results show that the structural similarity of graphs can be characterized by counting homomorphisms to them: the Tree Theorem states that the well-known color-refinement algorithm does not distinguish two graphs G and H if and only if, for every ... More
A realization of the Lie algebra associated to a Kantor triple systemApr 27 2005We present a nonlinear realization of the 5-graded Lie algebra associated to a Kantor triple system. Any simple Lie algebra can be realized in this way, starting from an arbitrary 5-grading. In particular, we get a unified realization of the exceptional ... More
Tensor hierarchies, Borcherds algebras and E11Oct 21 2011Mar 16 2012Gauge deformations of maximal supergravity in D=11-n dimensions generically give rise to a tensor hierarchy of p-form fields that transform in specific representations of the global symmetry group E(n). We derive the formulas defining the hierarchy from ... More
A generalization of the Kantor-Koecher-Tits constructionAug 17 2013The Kantor-Koecher-Tits construction associates a Lie algebra to any Jordan algebra. We generalize this construction to include also extensions of the associated Lie algebra. In particular, the conformal realization of so(p+1,q+1) generalizes to so(p+n,q+n), ... More
Computer Algebra Algorithms for Special Functions in Particle PhysicsMay 03 2013This work deals with special nested objects arising in massive higher order perturbative calculations in renormalizable quantum field theories. On the one hand we work with nested sums such as harmonic sums and their generalizations (S-sums, cyclotomic ... More
Simple transitive $2$-representations of some $2$-categories of projective functorsMay 02 2017We show that every simple transitive $2$-representation of the $2$-category of projective functors for a certain quotient of the quadratic dual of the preprojective algebra associated with a tree is equivalent to a cell $2$-representation.
Unifying N=5 and N=6Mar 24 2011Jul 10 2011We write the Lagrangian of the general N=5 three-dimensional superconformal Chern-Simons theory, based on a basic Lie superalgebra, in terms of our recently introduced N=5 three-algebras. These include N=6 and N=8 three-algebras as special cases. When ... More
Exactly realizable desired trajectoriesMar 02 2016Trajectory tracking of nonlinear dynamical systems with affine open-loop controls is investigated. The control task is to enforce the system state to follow a prescribed desired trajectory as closely as possible. We introduce exactly realizable desired ... More
Infinite-Dimensional Supermanifolds via Multilinear BundlesOct 12 2018Jan 22 2019In this paper, we provide an accessible introduction to the theory of locally convex supermanifolds in the categorical approach. In this setting, a supermanifold is a functor $\mathcal{M}\colon\mathbf{Gr}\to\mathbf{Man}$ from the category of Grassmann ... More
On the 3-torsion Part of the Homology of the Chessboard ComplexMar 26 2012Let $1 \le m \le n$. We prove various results about the chessboard complex $M_{m,n}$, which is the simplicial complex of matchings in the complete bipartite graph $K_{m,n}$. First, we demonstrate that there is nonvanishing 3-torsion in $H_d(M_{m,n};Z)$ ... More
Arakelov motivic cohomology IIMay 17 2012Oct 19 2013We show that the constructions done in part I generalize their classical counterparts: firstly, the classical Beilinson regulator is induced by the abstract Chern class map from $BGL$ to the Deligne cohomology spectrum. Secondly, Arakelov motivic cohomology ... More
Mixed Artin-Tate motives over number ringsMar 05 2010Aug 05 2010This paper studies Artin-Tate motives over number rings. As a subcategory of geometric motives, the triangulated category of Artin-Tate motives DATM(S) is generated by motives of schemes that are finite over the base S. After establishing stability of ... More
Non-elementary proper forcingOct 12 2009May 08 2011We introduce a simplified framework for ord-transitive models and Shelah's non elementary proper (nep) theory. We also introduce a new construction for the countable support nep iteration.
Preserving Non-Null with Suslin+ forcingNov 25 2002Feb 09 2005We introduce the notion of effective Axiom A and use it to show that some popular tree forcings are Suslin+. We introduce transitive nep and present a simplified version of Shelah's "preserving a little implies preserving much": If I is a Suslin ccc ideal ... More
Uniform central limit theorems for the Grenander estimatorNov 24 2014Jun 26 2015We consider the Grenander estimator that is the maximum likelihood estimator for non-increasing densities. We prove uniform central limit theorems for certain subclasses of bounded variation functions and for H\"older balls of smoothness s>1/2. We do ... More
Discovering and Proving Infinite Binomial Sums IdentitiesJul 07 2015Oct 29 2015We consider binomial and inverse binomial sums at infinity and rewrite them in terms of a small set of constants, such as powers of $\pi$ or $\log(2)$. In order to perform these simplifications, we view the series as specializations of generating series. ... More
Quantum vortex core and missing pseudogap in the multi-band BCS-BEC-crossover superconductor FeSeJan 26 2019FeSe is argued as a superconductor in the Bardeen-Cooper-Schrieffer Bose-Einstein-condensation crossover regime where the superconducting-gap size and the superconducting transition temperature Tc are comparable to the Fermi energy. In this regime, vortex ... More
Quantum dots. A survey of rigorous resultsDec 13 1998The paper reviews rigorous results about quantum dots, in particular exact solutions for few electron dots and limit theorems for high magnetic fields and/or high electron number.
Algebraic K-theory of the infinite placeFeb 23 2012Jun 05 2014In this note, we show that the algebraic K-theory of generalized archimedean valuation rings occurring in Durov's compactification of the spectrum of a number ring is given by stable homotopy groups of certain classifying spaces. We also show that the ... More
Demystifying Gauge SymmetryJan 29 2019Gauge symmetries are often highlighted as a fundamental cornerstone of modern physics. But at the same time, it is commonly emphasized that gauge symmetries are not a fundamental feature of nature but merely redundancies in our description. We argue that ... More
Optimal trajectory trackingDec 23 2015This thesis investigates optimal trajectory tracking of nonlinear dynamical systems with affine controls. The control task is to enforce the system state to follow a prescribed desired trajectory as closely as possible. The concept of so-called exactly ... More
Bosons in Rapid RotationAug 20 2008Some recent progress in the mathematical physics of rapidly rotating, dilute Bose gases in anharmonic traps is reviewed.
Coupled Kähler-Ricci solitons on toric Fano manifoldsNov 27 2017Oct 05 2018We prove a necessary and sufficient condition in terms of the barycenters of a collection of polytopes for existence of coupled K\"ahler-Einstein metrics on toric Fano manifolds. This confirms the toric case of a coupled version of the Yau-Tian-Donaldson ... More
On the Number of Periodic Points of Quadratic Dynamical Systems Modulo a PrimeNov 02 2016In 2004 Vasiga and Shallit studied the number of periodic points of two particular discrete quadratic maps modulo prime numbers. They found the asymptotic behaviour of the sum of the number of periodic points for all primes less than some bound, assuming ... More
Inverse Mellin Transform of Holonomic SequencesJun 09 2016We describe a method to compute the inverse Mellin transform of holonomic sequences, that is based on a method to compute the Mellin transform of holonomic functions. Both methods are implemented in the computer algebra package HarmonicSums.
Linear structures in nonlinear optimal controlApr 05 2016We investigate optimal control of dynamical systems which are affine, i.e., linear in control, but nonlinear in state. The control task is to enforce the system state to follow a prescribed desired trajectory as closely as possible, a task also known ... More
Practical Concurrent Priority QueuesSep 23 2015Priority queues are abstract data structures which store a set of key/value pairs and allow efficient access to the item with the minimal (maximal) key. Such queues are an important element in various areas of computer science such as algorithmics (i.e. ... More
Proceedings Seventh Workshop on Intersection Types and Related SystemsMar 15 2015This volume contains a final and revised selection of papers presented at the Seventh Workshop on Intersection Types and Related Systems (ITRS 2014), held in Vienna (Austria) on July 18th, affiliated with TLCA 2014, Typed Lambda Calculi and Applications ... More
Quantifying information transfer and mediation along causal pathways in complex systemsAug 16 2015Mar 18 2016Measures of information transfer have become a popular approach to analyze interactions in complex systems such as the Earth or the human brain from measured time series. Recent work has focused on causal definitions of information transfer excluding ... More
Comment on Wibral et al. (2013): Measuring information-transfer delays, PloS ONE 8(2): e55809Apr 30 2013Jan 16 2014Wibral et al. propose a measure of interaction delays rooted in an information-theoretic framework and contrast their measure with the bivariate momentary information transfer (MIT), introduced in Pompe, B., & Runge, J. (2011). Momentary information transfer ... More
Collaborative thesaurus tagging the Wikipedia wayApr 10 2006Apr 27 2006This paper explores the system of categories that is used to classify articles in Wikipedia. It is compared to collaborative tagging systems like and to hierarchical classification like the Dewey Decimal Classification (DDC). Specifics and ... More
Revealing digital documents. Concealed structures in dataMay 29 2011This short paper gives an introduction to a research project to analyze how digital documents are structured and described. Using a phenomenological approach, this research will reveal common patterns that are used in data, independent from the particular ... More
On groups with unbounded Cayley graphsNov 29 2018Jan 29 2019We show that every non-trivial compact connected group and every non-trivial general or special linear group over an infinite field admits a generating set such that the associated Cayley graph has infinite diameter.
Topics in the Mathematical Physics of Cold Bose GasesFeb 04 2014Feb 14 2014In these notes of six lectures on selected topics in the theory of cold, dilute Bose gases, presented at the 5th Warsaw School of Statistical Physics in June 2013, the following topics are discussed: 1) The concept of BEC, 2) the ground state energy of ... More
Trading degree for dimension in the section conjecture: The non-abelian Shapiro LemmaFeb 10 2009This note aims at providing evidence for the section conjecture of anabelian geometry by establishing its behaviour under Weil restriction of scalars. In particular, the etale fundamental group of the Weil restriction is determined by means of a Shapiro ... More
On cuspidal sections of algebraic fundamental groupsAug 29 2008Rational points in the boundary of a hyperbolic curve over a field with sufficiently nontrivial Kummer theory are the source for an abundance of sections of the fundamental group exact sequence. We follow and refine Nakamura's approach towards these boundary ... More
Constructing pairs of dual bandlimited frame wavelets in $L^2(\mathbb{R}^n)$Sep 22 2010Given a real, expansive dilation matrix we prove that any bandlimited function $\psi \in L^2(\mathbb{R}^n)$, for which the dilations of its Fourier transform form a partition of unity, generates a wavelet frame for certain translation lattices. Moreover, ... More
On some Hermite series identities and their applications to Gabor analysisNov 30 2015We prove some infinite series identities for the Hermite functions. From these identities we disprove the Gabor frame set conjecture for Hermite functions of order $4m+2$ and $4m+3$ for $m \in \{0\} \cup \mathbb{N}$. The results hold not only for Hermite ... More
Quasi-symmetric functions and the Chow ring of the stack of expanded pairsJun 27 2018We show that the Hopf algebra of quasi-symmetric functions arises naturally as the integral Chow ring of the algebraic stack of expanded pairs originally described by J. Li, using a more combinatorial description in terms of configurations of line bundles. ... More
Classification of Rigid Irregular $G_2$-ConnectionsSep 12 2016Jul 16 2018Using the Katz-Arinkin algorithm we give a classification of irreducible rigid irregular connections on a punctured $\mathbb{P}^1_{\mathbb{C}}$ having differential Galois group $G_2$, the exceptional simple algebraic group, and slopes having numerator ... More
New entropic uncertainty relations for prime power dimensionsSep 30 2011We consider the question of entropic uncertainty relations for prime power dimensions. In order to improve upon such uncertainty relations for higher dimensional quantum systems, we derive a tight lower bound amount of entropy for multiple probability ... More
A Computer Algebra Toolbox for Harmonic Sums Related to Particle PhysicsNov 04 2010In this work we present the computer algebra package HarmonicSums and its theoretical background for the manipulation of harmonic sums and some related quantities as for example Euler-Zagier sums and harmonic polylogarithms. Harmonic sums and generalized ... More
Borcherds and Kac-Moody extensions of simple finite-dimensional Lie algebrasMar 22 2012Jul 12 2012We study the Borcherds superalgebra obtained by adding an odd (fermionic) null root to the set of simple roots of a simple finite-dimensional Lie algebra. We compare it to the Kac-Moody algebra obtained by replacing the odd null root by an ordinary simple ... More
Exceptional Lie algebras and M-theoryDec 08 2009In this thesis we study algebraic structures in M-theory, in particular the exceptional Lie algebras arising in dimensional reduction of its low energy limit, eleven-dimensional supergravity. We focus on e8 and its infinite-dimensional extensions e9 and ... More
Permanental Point Processes on Real Tori, Theta Functions and Monge-Ampère EquationsApr 19 2016May 18 2016Inspired by constructions in complex geometry we introduce a thermodynamic framework for Monge-Amp\`ere equations on real tori. We show convergence in law of the associated point processes and explain connections to complex Monge-Amp\`ere equations and ... More
Exceptional geometry and Borcherds superalgebrasJul 31 2015Jun 20 2016We study generalized diffeomorphisms in exceptional geometry with U-duality group E_{n(n)} from an algebraic point of view. By extending the Lie algebra e_n to an infinite-dimensional Borcherds superalgebra, involving also the extension to e_{n+1}, the ... More
Discovering and Proving Infinite Pochhammer Sum IdentitiesFeb 28 2019We consider nested sums involving the Pochhammer symbol at infinity and rewrite them in terms of a small set of constants, such as powers of $\pi,$ $\log(2)$ or zeta values. In order to perform these simplifications, we view the series as specializations ... More
On the graph-theoretical interpretation of Pearson correlations in a multivariate process and a novel partial correlation measureOct 18 2013The dependencies of the lagged (Pearson) correlation function on the coefficients of multivariate autoregressive models are interpreted in the framework of time series graphs. Time series graphs are related to the concept of Granger causality and encode ... More
Tagging, Folksonomy & Co - Renaissance of Manual Indexing?Jan 10 2007Jan 26 2007This paper gives an overview of current trends in manual indexing on the Web. Along with a general rise of user generated content there are more and more tagging systems that allow users to annotate digital resources with tags (keywords) and share their ... More
Even more simple cardinal invariantsJun 03 2007Jul 16 2007Using GCH, we force the following: There are continuum many simple cardinal characteristics with pairwise different values.
A logarithmic view towards semistable reductionMay 18 2003The geometric condition of T. Saito for trivial action of the wild monodromy of a smooth proper curve over the generic point of a trait is transformed to the condition of logarithmic smooth reduction. The proof emphasizes methods and results from logarithmic ... More
The Role of Type III Factors in Quantum Field TheoryNov 17 2004Dec 04 2004One of von Neumann's motivations for developing the theory of operator algebras and his and Murray's 1936 classification of factors was the question of possible decompositions of quantum systems into independent parts. For quantum systems with a finite ... More
f-cohomology and motives over number ringsMar 05 2010Mar 16 2015This paper is concerned with an interpretation of f-cohomology, a modification of motivic cohomology of motives over number fields, in terms of motives over number rings. Under standard assumptions on mixed motives over finite fields, number fields and ... More
Exact Sequences for the Homology of the Matching ComplexMar 26 2012Building on work by Bouc and by Shareshian and Wachs, we provide a toolbox of long exact sequences for the reduced simplicial homology of the matching complex $M_n$, which is the simplicial complex of matchings in the complete graph $K_n$. Combining these ... More
Five-Torsion in the Homology of the Matching Complex on 14 VerticesMar 26 2012J. L. Andersen proved that there is 5-torsion in the bottom nonvanishing homology group of the simplicial complex of graphs of degree at most two on seven vertices. We use this result to demonstrate that there is 5-torsion also in the bottom nonvanishing ... More
On the birational section conjecture with local conditionsMar 14 2012Sep 17 2015A birationally liftable Galois section s of a hyperbolic curve X/k over a number field k yields an adelic point x(s) in the smooth completion of X. We show that x(s) is X-integral outside a set of places of Dirichlet density 0, or s is cuspidal. The proof ... More
The Brauer-Manin obstruction for sections of the fundamental groupOct 26 2009We establish Grothendieck's section conjecture for an open subset of the Reichardt-Lind curve, and introduce the notion of a Brauer-Manin obstruction for sections of the fundamental group extension.
A monodromy criterion for extending curvesAug 23 2004Nov 10 2004A family of proper smooth curves of genus $\geq 2$, parametrised by an open dense subset $U$ of a normal variety $S$, extends to $S$ if the natural map $\pi_1(U) \to \pi_1(S)$ on fundamental groups is an isomorphism. The criterion of this note is actually ... More
Affine anabelian curves in positive characteristicJun 18 2002An investigation of morphisms that coincide topologically is used to generalize to all characteristics and partly reprove Tamagawa's theorem on the Grothendieck conjecture in anabelian geometry for affine hyperbolic curves. The theorem now deals with ... More
Conic bundles and iterated root stacksSep 25 2017Jun 21 2018We generalize a classical result by V. G. Sarkisov about standard models for conic bundles to the case of a not necessarily algebraically closed perfect field, using iterated root stacks, destackification, and resolution of singularities.
Discovering and Proving Infinite Pochhammer Sum IdentitiesFeb 28 2019Apr 10 2019We consider nested sums involving the Pochhammer symbol at infinity and rewrite them in terms of a small set of constants, such as powers of $\pi,$ $\log(2)$ or zeta values. In order to perform these simplifications, we view the series as specializations ... More
Connecting generalized parton distributions and light-cone wave functionsSep 26 2000The relation of generalized (skewed) quark distributions to nucleon wave functions is discussed in the context of light-cone quantization.
Wide Angle Compton ScatteringOct 16 2000We present the handbag contribution to Wide Angle Compton Scattering (WACS) at moderately large momentum transfer obtained with a proton distribution amplitude close to the asymptotic form. In comparison it is found to be significantly larger than results ... More
Proton-Proton Elastic Scattering; Landshoff Contributions in the Diquark ModelJun 08 1994Independent multiple scattering (`Landshoff') contributions to proton-proton elastic scattering at wide angles are calculated in the quark-diquark model. Results confirm previous observations about the magnitude of these contributions. The use of the ... More
The Classification of Rigid Irregular $G_2$-ConnectionsSep 12 2016Sep 28 2016Using the Katz-Arinkin algorithm we give a complete classification of irreducible rigid irregular connections on a punctured $\mathbb{P}^1_{\mathbb{C}}$ having differential Galois group $G_2$, the exceptional simple algebraic group. In addition to hypergeometric ... More
A note on the Thom isomorphism in geometric (co)homologyMar 31 2004Using geometric homology and cohomology we give a simple and conceptual proof of the Thom isomorphism theorem.
Localization and Entanglement in Relativistic Quantum PhysicsJan 12 2014The combination of quantum theory and special relativity leads to structures that differ in several respects from non-relativistic quantum mechanics of particles. These differences are quite familiar to practitioners of Algebraic Quantum Field Theory ... More
On the Relative Strength of Pebbling and ResolutionMar 15 2010Apr 22 2010The last decade has seen a revival of interest in pebble games in the context of proof complexity. Pebbling has proven a useful tool for studying resolution-based proof systems when comparing the strength of different subsystems, showing bounds on proof ... More
Generalized conformal realizations of Kac-Moody algebrasNov 03 2007Nov 17 2008We present a construction which associates an infinite sequence of Kac-Moody algebras, labeled by a positive integer n, to one single Jordan algebra. For n=1, this reduces to the well known Kantor-Koecher-Tits construction. Our generalization utilizes ... More
The Arithmetic Katz-Arinkin Algorithm and Wildly Ramified Rigid $G_2$-Local SystemsJul 26 2018We employ the arithmetic version of the Katz-Arinkin algorithm to give a classification of wildly ramified irreducible rigid $\ell$-adic local systems on open subsets of $\mathbb{P}^1_k$, $k$ the algebraic closure of a finite field, with monodromy group ... More
Conditional Value-at-Risk: Theory and ApplicationsOct 31 2015This thesis presents the Conditional Value-at-Risk concept and combines an analysis that covers its application as a risk measure and as a vector norm. For both areas of application the theory is revised in detail and examples are given to show how to ... More
Simple transitive $2$-representations of left cell $2$-subcategories of projective functors for star algebrasMay 15 2018In this paper we study simple transitive $2$-representations of certain $2$-subcategories of the $2$-category of projective functors over a star algebra. We show that in the simplest case, which is associated to the Dynkin type $A_2$, simple transitive ... More
The package HarmonicSums: Computer Algebra and Analytic aspects of Nested SumsJul 23 2014This paper summarizes the essential functionality of the computer algebra package HarmonicSums. On the one hand HarmonicSums can work with nested sums such as harmonic sums and their generalizations and on the other hand it can treat iterated integrals ... More
The tensor hierarchy algebraApr 30 2013We introduce an infinite-dimensional Lie superalgebra which is an extension of the U-duality Lie algebra of maximal supergravity in D dimensions, for D between 3 and 7. The level decomposition with respect to the U-duality Lie algebra gives exactly the ... More
Pebble Games, Proof Complexity, and Time-Space Trade-offsJul 15 2013Sep 20 2013Pebble games were extensively studied in the 1970s and 1980s in a number of different contexts. The last decade has seen a revival of interest in pebble games coming from the field of proof complexity. Pebbling has proven to be a useful tool for studying ... More
Dark Matter in $E_6$ Grand UnificationApr 13 2017We discuss fermionic dark matter in non-supersymmetric $E_6$ Grand Unification. The fundamental representation of $E_6$ contains, in addition to the standard model fermions, exotic fermions and we argue that one of them is a viable, interesting dark matter ... More
Attacks on Fitness Trackers Revisited: A Case-Study of Unfit Firmware SecurityApr 12 2016Fitness trackers - wearables that continuously record a wearer's step count and related activity data - are quickly gaining in popularity. Apart from being useful for individuals seeking a more healthy lifestyle, their data is also being used in court ... More
Conditional independence testing based on a nearest-neighbor estimator of conditional mutual informationSep 05 2017Conditional independence testing is a fundamental problem underlying causal discovery and a particularly challenging task in the presence of nonlinear and high-dimensional dependencies. Here a fully non-parametric test for continuous data based on conditional ... More
Encoding changing country codes for the Semantic Web with ISO 3166 and SKOSJan 25 2008This paper shows how authority files can be encoded for the Semantic Web with the Simple Knowledge Organisation System (SKOS). In particular the application of SKOS for encoding the structure, management, and utilization of country codes as defined in ... More
On the average distribution of primes represented by binary quadratic formsDec 05 2013We investigate the average distribution of primes represented by positive definite integral binary quadratic forms, the average being taken over negative fundamental discriminants in long ranges. In particular, we prove corresponding results of Bombieri-Vinogradov ... More
On the period-index problem in light of the section conjectureFeb 28 2008Period and index of a curve $X/K$ over a $p$-adic local field $K$ such that the fundamental group $\pi_1(X/K)$ admits a splitting are shown to be powers of $p$. As a consequence, examples of curves over number fields are constructed where having sections ... More
More Torsion in the Homology of the Matching ComplexMar 26 2012Mar 28 2012A matching on a set $X$ is a collection of pairwise disjoint subsets of $X$ of size two. Using computers, we analyze the integral homology of the matching complex $M_n$, which is the simplicial complex of matchings on the set $\{1, >..., n\}$. The main ... More
Special L-values of geometric motivesMar 05 2010Aug 03 2015This paper proposes a conjecture on special values of L-functions of geometric motives over Z. This includes L-functions of mixed motives over Q and Hasse-Weil zeta-functions of schemes over Z. We conjecture the following: the order of L(M, s) at s=0 ... More
A SINFONI view of Galaxy Centers: Morphology and Kinematics of five Nuclear Star Formation RingsOct 22 2007We present near-infrared (H- and K-band) integral-field observations of the circumnuclear star formation rings in five nearby spiral galaxies. The data, obtained at the Very Large Telescope with the SINFONI spectrograph, are used to construct maps of ... More
Physics at the LHC -- From Standard Model measurements to Searches for New PhysicsJun 29 2012The successful operation of the {\em Large Hadron Collider} (LHC) during the past two years allowed to explore particle interaction in a new energy regime. Measurements of important Standard Model processes like the production of high-\pt\ jets, $W$ and ... More
Spin-dependent Fragmentation FunctionsJun 26 2002I will give an overview on fragmentation functions with particular emphasis on spin-dependence. A straightforward classification scheme permits to label all independent fragmentation functions for a given physical situation in an unambiguous way. In the ... More
Computing the Inverse Mellin Transform of Holonomic Sequences using Kovacic's AlgorithmJan 02 2018We describe how the extension of a solver for linear differential equations by Kovacic's algorithm helps to improve a method to compute the inverse Mellin transform of holonomic sequences. The method is implemented in the computer algebra package HarmonicSums. ... More
Three-algebras, triple systems and 3-graded Lie superalgebrasMay 15 2009Dec 08 2009The three-algebras used by Bagger and Lambert in N=6 theories of ABJM type are in one-to-one correspondence with a certain type of Lie superalgebras. We show that the description of three-algebras as generalized Jordan triple systems naturally leads to ... More
Simple transitive $2$-representations of Soergel bimodules in type $B_2$Sep 04 2015Jun 17 2016We prove that every simple transitive $2$-representation of the fiat $2$-category of Soergel bimodules (over the coinvariant algebra) in type $B_2$ is equivalent to a cell $2$-representation. We also describe some general properties of the $2$-category ... More
Stability of position control of traveling waves in reaction-diffusion systemsDec 30 2013We consider the stability of position control of traveling waves in reaction-diffusion system as proposed in {[}J. L\"ober, H. Engel, arXiv:1304.2327{]}. Instead of analyzing the controlled reaction-diffusion system, stability is studied on the reduced ... More
SST polarization model and polarimeter calibrationOct 20 2010A telescope polarization model for the SST [Swedish 1-m Solar Telescope] is developed and the parameters of this model are fitted to polarization measurements made with a 1-meter linear polarizer in front of the entrance window. In this model, the 1-meter ... More
Gauge Coupling Unification without SupersymmetryAug 30 2018Oct 16 2018We investigate the prospects to achieve unification of the gauge couplings in models without supersymmetry. We restrict our discussion to $SU(5), SO(10)$ and $E_6$ models that mimic the structure of the Standard Model as much as possible ("conservative ... More
Pitowsky's Kolmogorovian models and Super-DeterminismJun 22 2016Sep 28 2016In an attempt to demonstrate that local hidden variables are mathematically possible, Pitowsky constructed "spin-$\frac12$ functions" and later "Kolmogorovian models", which employs a nonstandard notion of probability. We describe Pitowsky's analysis ... More
Geometric Brauer residue via root stacksMar 12 2018Jun 21 2018We reinterpret the residue map for the Brauer group of a smooth variety using a root stack construction and Weil restriction for algebraic stacks, and apply the result to find a geometric representative of for the residue of a Brauer class associated ... More
Birational p-adic Galois sections in higher dimensionsFeb 13 2012This note explores the consequences of Koenigsmann's model theoretic argument from the proof of the birational p-adic section conjecture for curves in the context of higher dimensional varieties over p-adic local fields.
Polar sets of anisotropic Gaussian random fieldsAug 03 2012This paper studies polar sets of anisotropic Gaussian random fields, i.e. sets which a Gaussian random field does not hit almost surely. The main assumptions are that the eigenvalues of the covariance matrix are bounded from below and that the canonical ... More
Confidence sets in nonparametric calibration of exponential Lévy modelsFeb 29 2012Sep 19 2013Confidence intervals and joint confidence sets are constructed for the nonparametric calibration of exponential L\'evy models based on prices of European options. To this end, we show joint asymptotic normality in the spectral calibration method for the ... More
Symmetry Groups of Principal Bundles Over Non-Compact BasesOct 31 2013Nov 06 2013In this work, we describe how to obtain the structure of an infinite-dimensional Lie group on the group of compactly carried bundle automorphisms Autc(P) for a locally convex prinicpal bundle P over a finite-dimensional smooth sigma-compact base M. This ... More