Results for "Wolfgang König"

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Brownian motion in a truncated Weyl chamberAug 18 2010We examine the non-exit probability of a multidimensional Brownian motion from a growing truncated Weyl chamber. Different regimes are identified according to the growth speed, ranging from polynomial decay over stretched-exponential to exponential decay. ... More
Routeing properties in a Gibbsian model for highly dense multihop networksDec 20 2017Feb 15 2019We investigate a probabilistic model for routeing in a multihop ad-hoc communication network, where each user sends a message to the base station. Messages travel in hops via other users, used as relays. Their trajectories are chosen at random according ... More
Geometric characterization of intermittency in the parabolic Anderson modelJul 28 2005Jul 25 2007We consider the parabolic Anderson problem $\partial_tu=\Delta u+\xi(x)u$ on $\mathbb{R}_+\times\mathbb{Z}^d$ with localized initial condition $u(0,x)=\delta_0(x)$ and random i.i.d. potential $\xi$. Under the assumption that the distribution of $\xi(0)$ ... More
Moment asymptotics for multitype branching random walks in random environmentOct 29 2013We study a discrete time multitype branching random walk on a finite space with finite set of types. Particles follow a Markov chain on the spatial space whereas offspring distributions are given by a random field that is fixed throughout the evolution ... More
Doves and hawks in economics revisited. An evolutionary quantum game theory-based analysis of financial crisesApr 14 2009The last financial and economic crisis demonstrated the dysfunctional long-term effects of aggressive behaviour in financial markets. Yet, evolutionary game theory predicts that under the condition of strategic dependence a certain degree of aggressive ... More
Upper tails of self-intersection local times of random walks: survey of proof techniquesNov 13 2010The asymptotics of the probability that the self-intersection local time of a random walk on $\Z^d$ exceeds its expectation by a large amount is a fascinating subject because of its relation to some models from Statistical Mechanics, to large-deviation ... More
Routeing properties in a Gibbsian model for highly dense multihop networksDec 20 2017Jul 12 2018We investigate a probabilistic model for routeing in a multihop ad-hoc communication network, where each user sends a message to the base station. Messages travel in hops via the other users, used as relays. Their trajectories are chosen at random according ... More
The longest excursion of a random interacting polymerMar 01 2011We consider a random $N$-step polymer under the influence of an attractive interaction with the origin and derive a limit law -- after suitable shifting and norming -- for the length of the longest excursion towards the Gumbel distribution. The embodied ... More
Large deviations for many Brownian bridges with symmetrised initial-terminal conditionMar 30 2006Consider a large system of $N$ Brownian motions in $\mathbb{R}^d$ with some non-degenerate initial measure on some fixed time interval $[0,\beta]$ with symmetrised initial-terminal condition. That is, for any $i$, the terminal location of the $i$-th motion ... More
Interacting Brownian motions and the Gross-Pitaevskii formulaSep 18 2007We review probabilistic approaches to the Gross-Pitaevskii theory describing interacting dilute systems of particles. The main achievement are large deviations principles for the mean occupation measure of a large system of interacting Brownian motions ... More
A Gibbsian model for message routeing in highly dense multihop networksApr 11 2017Aug 13 2018We investigate a probabilistic model for routeing of messages in relay-augmented multihop ad-hoc networks, where each transmitter sends one message to the origin. Given the (random) transmitter locations, we weight the family of random, uniformly distributed ... More
Large deviations for the local times of a random walk among random conductances in a growing boxAug 21 2013We derive an annealed large deviation principle (LDP) for the normalised and rescaled local times of a continuous-time random walk among random conductances (RWRC) in a time-dependent, growing box in $\Z^d$. We work in the interesting case that the conductances ... More
Self-intersection local times of random walks: Exponential moments in subcritical dimensionsJul 23 2010Jun 09 2011Fix $p>1$, not necessarily integer, with $p(d-2)<d$. We study the $p$-fold self-intersection local time of a simple random walk on the lattice $\Z^d$ up to time $t$. This is the $p$-norm of the vector of the walker's local times, $\ell_t$. We derive precise ... More
On number fields with $k$-free discriminantsSep 06 2018Given a finite transitive permutation group $G$, we investigate number fields $F/\mathbb{Q}$ of Galois group $G$ whose discriminant is only divisible by small prime powers. This generalizes previous investigations of number fields with squarefree discriminant. ... More
On the number of cyclic transitive subgroups of a permutation groupJan 26 2015Feb 09 2015We prove an upper bound for the number of cyclic transitive subgroups in a finite permutation group and clarify the structure of the groups for which this bound becomes sharp. We also give an application in the theory of number fields.
On rational functions with monodromy group $M_{11}$Mar 23 2015Dec 14 2015We compute new polynomials with Galois group $M_{11}$ over $\mathbb{Q}(t)$. These polynomials stem from various families of covers of $\mathbb{P}^1\mathbb{C}$ ramified over at least 4 points. Each of these families has features that make a detailed study ... More
A note on the product of two permutations of prescribed ordersAug 10 2015We prove a conjecture by Stefan Kohl on the existence of triples of permutations of bounded degree with prescribed orders and product 1. This result leads to an existence result for covers of the complex projective line with bounded degree and prescribed ... More
Large deviations for trapped interacting Brownian particles and pathsNov 30 2004Sep 22 2006We introduce two probabilistic models for $N$ interacting Brownian motions moving in a trap in $\mathbb {R}^d$ under mutually repellent forces. The two models are defined in terms of transformed path measures on finite time intervals under a trap Hamiltonian ... More
Connection times in large ad-hoc mobile networksMar 15 2013Jun 06 2016We study connectivity properties in a probabilistic model for a large mobile ad-hoc network. We consider a large number of participants of the system moving randomly, independently and identically distributed in a large domain, with a space-dependent ... More
An embedding for the Kesten-Spitzer random walk in random sceneryDec 31 1998For one-dimensional simple random walk in a general i.i.d. scenery and its limiting process we construct a coupling with explicit rate of approximation extending a recent result for Gaussian sceneries due to Khoshnevisan and Lewis. Furthermore we explicity ... More
Large deviations for cluster size distributions in a continuous classical many-body systemJul 19 2011Mar 17 2015An interesting problem in statistical physics is the condensation of classical particles in droplets or clusters when the pair-interaction is given by a stable Lennard-Jones-type potential. We study two aspects of this problem. We start by deriving a ... More
Moment asymptotics for branching random walks in random environmentAug 01 2012We consider the long-time behaviour of a branching random walk in random environment on the lattice $\Z^d$. The migration of particles proceeds according to simple random walk in continuous time, while the medium is given as a random potential of spatially ... More
A variational formula for the free energy of an interacting many-particle systemMar 06 2010Apr 19 2011We consider $N$ bosons in a box in $\mathbb {R}^d$ with volume $N/\rho$ under the influence of a mutually repellent pair potential. The particle density $\rho\in (0,\infty)$ is kept fixed. Our main result is the identification of the limiting free energy, ... More
Large deviations for the local times of a random walk among random conductancesApr 08 2011We derive an annealed large deviation principle for the normalised local times of a continuous-time random walk among random conductances in a finite domain in $\Z^d$ in the spirit of Donsker-Varadhan \cite{DV75}. We work in the interesting case that ... More
Annealed deviations of random walk in random sceneryAug 24 2004Nov 21 2005Let $(Z_n)_{n\in\N}$ be a $d$-dimensional {\it random walk in random scenery}, i.e., $Z_n=\sum_{k=0}^{n-1}Y(S_k)$ with $(S_k)_{k\in\N_0}$ a random walk in $\Z^d$ and $(Y(z))_{z\in\Z^d}$ an i.i.d. scenery, independent of the walk. The walker's steps have ... More
Violation of detailed balance for charge-transfer statistics in Coulomb-blockade systemsOct 14 2016May 21 2017We discuss the possibility to generate in Coulomb-blockade systems steady states that violate detailed balance. This includes both voltage biased and non-biased scenarios. The violation of detailed balance yields that the charge-transfer statistics for ... More
Surface energy and boundary layers for a chain of atoms at low temperatureApr 12 2019We analyze the surface energy and boundary layers for a chain of atoms at low temperature for an interaction potential of Lennard-Jones type. The pressure (stress) is assumed small but positive and bounded away from zero, while the temperature $\beta^{-1}$ ... More
Interaction-driven spin precession in quantum-dot spin valvesDec 11 2002Apr 23 2003We analyze spin-dependent transport through spin valves composed of an interacting quantum dot coupled to two ferromagnetic leads. The spin on the quantum dot and the linear conductance as a function of the relative angle $\theta$ of the leads' magnetization ... More
A large-deviations approach to gelationJan 07 2019A large-deviations principle (LDP) is derived for the state at fixed time, of the multiplicative coalescent in the large particle number limit. The rate function is explicit and describes each of the three parts of the state: microscopic, mesoscopic and ... More
Joint density for the local times of continuous-time Markov chainsNov 17 2006Aug 13 2007We investigate the local times of a continuous-time Markov chain on an arbitrary discrete state space. For fixed finite range of the Markov chain, we derive an explicit formula for the joint density of all local times on the range, at any fixed time. ... More
Deviations of a random walk in a random scenery with stretched exponential tailsNov 16 2004Aug 09 2005Let (Z_n)_{n\in\N_0} be a d-dimensional random walk in random scenery, i.e., Z_n=\sum_{k=0}^{n-1}Y_{S_k} with (S_k)_{k\in\N_0} a random walk in Z^d and (Y_z)_{z\in Z^d} an i.i.d. scenery, independent of the walk. We assume that the random variables Y_z ... More
A two cities theorem for the parabolic Anderson modelFeb 24 2011The parabolic Anderson problem is the Cauchy problem for the heat equation $\partial_tu(t,z)=\Delta u(t,z)+\xi(z)u(t,z)$ on $(0,\infty)\times {\mathbb{Z}}^d$ with random potential $(\xi(z):z\in{\mathbb{Z}}^d)$. We consider independent and identically ... More
Some examples of quadratic fields with finite nonsolvable maximal unramified extensions IISep 25 2017Let $K$ be a number field and $K_{ur}$ be the maximal extension of $K$ that is unramified at all places. In a previous article, the first author found three real quadratic fields $K$ such that $Gal(K_{ur}/K)$ is finite and nonabelian simple under the ... More
Splitting the relative assembly map, Nil-terms and involutionsJan 12 2015Oct 06 2015We show that the relative Farrell-Jones assembly map from the family of finite subgroups to the family of virtually cyclic subgroups for algebraic K-theory is split injective in the setting where the coefficients are additive categories with group action. ... More
Causality constraints for charged particlesOct 31 2012Mar 12 2013In quantum systems with short-range interactions, causality imposes nontrivial constraints on low-energy scattering parameters. We investigate these causality constraints for systems where a long-range Coulomb potential is present in addition to a short-range ... More
Consistent Searches for SMEFT Effects in Non-Resonant Dilepton EventsDec 18 2018Employing the framework of the Standard Model Effective Field Theory, we perform a detailed reinterpretation of measurements of the Weinberg angle in dilepton production as a search for new-physics effects. We truncate our signal prediction at order $1/\Lambda^2$, ... More
Multidimensional multiscale scanning in Exponential Families: Limit theory and statistical consequencesFeb 22 2018Mar 24 2019We consider the problem of finding anomalies in a $d$-dimensional field of independent random variables $\{Y_i\}_{i \in \left\{1,...,n\right\}^d}$, each distributed according to a one-dimensional natural exponential family $\mathcal F = \left\{F_\theta\right\}_{\theta ... More
Fixed Parameter Complexity and Approximability of Norm MaximizationJul 24 2013The problem of maximizing the $p$-th power of a $p$-norm over a halfspace-presented polytope in $\R^d$ is a convex maximization problem which plays a fundamental role in computational convexity. It has been shown in 1986 that this problem is $\NP$-hard ... More
Comment on "Do Intradot Electron-Electron Interactions Induce Dephasing?"Aug 24 2004May 05 2005In a recent Letter, Jiang, Sun, Xie and Wang [Phys. Rev. Lett. 93, 076802 (2004), cond-mat/0408261] study transport through an interacting quantum dot embedded in one arm of an Aharonov-Bohm interferometer. Based on a theoretical analysis of the Aharonov-Bohm ... More
Nuclear parton density modifications from low-mass lepton pair production at the LHCJan 27 2014In this article, we investigate the potential of low-mass lepton pair production in proton-ion collisions at the LHC to constrain nuclear modifications of parton densities. Similarly to prompt photon production, the transverse momentum spectrum is shown ... More
Neutrino Anarchy and Renormalization Group EvolutionNov 19 2015May 25 2016The observed pattern of neutrino mixing angles is in good agreement with the hypothesis of neutrino anarchy, which posits that Nature has chosen the entries of the leptonic mixing matrix at random. In this paper we investigate how stable this conclusion ... More
Kondo Correlations and the Fano Effect in Closed AB-InterferometersApr 25 2001Oct 01 2001We study the Fano-Kondo effect in a closed Aharonov-Bohm (AB) interferometer which contains a single-level quantum dot and predict a frequency doubling of the AB oscillations as a signature of Kondo-correlated states. Using Keldysh formalism, Friedel ... More
Up-To Techniques for Behavioural Metrics via FibrationsJun 28 2018Up-to techniques are a well-known method for enhancing coinductive proofs of behavioural equivalences. We introduce up-to techniques for behavioural metrics between systems modelled as coalgebras and we provide abstract results to prove their oundness ... More
The complex Busemann-Petty problem on sections of convex bodiesJul 26 2007The complex Busemann-Petty problem asks whether origin symmetric convex bodies in $\C^n$ with smaller central hyperplane sections necessarily have smaller volume. We prove that the answer is affirmative if $n\le 3$ and negative if $n\ge 4.$
Effective Field Theory after a New-Physics DiscoveryJun 04 2018Aug 09 2018When a new heavy particle is discovered at the LHC or at a future high-energy collider, it will be interesting to study its decays into Standard Model particles using an effective field-theory framework. We point out that the proper effective theory can ... More
A Joint Motion Model for Human-Like Robot-Human HandoverAug 28 2018In future, robots will be present in everyday life. The development of these supporting robots is a challenge. A fundamental task for assistance robots is to pick up and hand over objects to humans. By interacting with users, soft factors such as predictability, ... More
Supersymmetric QCD corrections to quark pair production in e+ e- annihilationMay 25 1993We calculate supersymmetric QCD corrections (squark/gluino loops) to quark pair production in e+ e- annihilation, allowing for mixing between left- and right-handed squarks and taking into account the effects of nonzero quark masses. Corrections to the ... More
SwarmRob: A Toolkit for Reproducibility and Sharing of Experimental Artifacts in Robotics ResearchJan 12 2018Jan 25 2018Due to the complexity of robotics, the reproducibility of results and experiments is one of the fundamental problems in robotics research. While the problem has been identified by the community, the approaches that address the problem appropriately are ... More
Simplicial Differential Calculus, Divided Differences, and Construction of Weil FunctorsSep 13 2010Jan 11 2011We define a simplicial differential calculus by generalizing divided differences from the case of curves to the case of general maps, defined on general topological vector spaces, or even on modules over a topological ring K. This calculus has the advantage ... More
Probing the MSSM flavor structure with low energy CP violationSep 15 2009We report on an extensive analysis of FCNC and CPV effects in SUSY theories. We present results for Delta F=2 and Delta F=1 processes governed by b --> s transitions both in the low and high tanbeta regime, focussing in particular on S_psi_phi, the phase ... More
On Calibrating Stochastic Volatility Models with time-dependent ParametersOct 06 2010We consider stochastic volatility models using piecewise constant parameters. We suggest a hybrid optimization algorithm for fitting the models to a volatility surface and provide some numerical results. Finally, we provide an outlook on how to further ... More
Comment on the paper: Quantum backaction of optical observations on Bose-Einstein condensates by U. Leonhardt, T. Kiss, and P. Piwnicki, Eur. Phys. J. D7, 413 (1999)Jun 27 2000A recent paper, Quantum backaction of optical observations on Bose-Einstein condensates by U. Leonhardt, T. Kiss, and P. Piwnicki, Eur. Phys. J. D7, 413 (1999), emphasized that the limit of dispersive imaging of Bose-Einstein condensates with off-resonant ... More
Supersymmetry and other beyond the Standard Model physics: Prospects for determining mass, spin and CP propertiesDec 10 2008The prospects of measuring masses, spin and CP properties within Supersymmetry and other beyond the Standard Model extensions at the LHC are reviewed. Emphasis is put on models with missing transverse energy due to undetected particles, as in Supersymmetry ... More
Westerlund 1 and its Galactic siblings -Observation confronts TheoryMar 13 2008Because of their large number of stars spread over the entire stellar mass spectrum, starburst clusters are highly suitable to benchmark and calibrate star formation models and theories. Among the handful of Galactic starburst clusters, Westerlund 1 with ... More
Full Salpeter Equation with Confining Interactions: Analytic Stability ProofOct 30 2008The most popular 3-dimensional reduction of the Bethe-Salpeter formalism for the description of bound states within quantum field theory is the Salpeter equation, found as the instantaneous limit of the Bethe-Salpeter framework if allowing, in addition, ... More
Light scalar meson spectrumNov 23 2001We discuss the classification of the light scalar mesons with mass below 2 GeV into q qbar nonets and glueballs. The information on production and decay of these states, in particular recent information on f_0(980), f_0(400-1200) (or sigma(600)) and f_0(1500) ... More
Scalar mesons: in search of the lightest glueballSep 20 2006According to the QCD expectations the lightest glueball should be a scalar particle (J^{PC}=0^{++}). Different scenarios have been considered for a classification of these states but -- despite considerable progress in recent years -- the experimental ... More
The Calculus of Expected Loss: Backtesting Parameter-Based Expected Loss in a Basel II FrameworkNov 21 2012Aug 08 2013The dependency structure of credit risk parameters is a key driver for capital consumption and receives regulatory and scientific attention. The impact of parameter imperfections on the quality of expected loss (EL) in the sense of a fair, unbiased estimate ... More
On the Solvability of Maxwell's EquationsSep 13 2012Complementing a study which was published in this journal in 2005, we present explicit calculations of fields predicted by Maxwell's equations both in Lorenz and in Coulomb gauge. Analytic expressions are obtainable, when the source of the fields is an ... More
On Scalar and Vector Potentials for the Nonlinear Electromagnetic ForcesMay 08 2008The potential concept that is successful in classical electrodynamics should also be applicable to the nonlinear electromagnetic forces acting on matter. The obvious method of determining these potentials should be provided by Helmholtz's theorem. It ... More
Comment on: I-Shih Liu: Constitutive theory of anisotropic rigid heat conductorsJun 15 2011In I-Shih Liu's paper \C{1}, the compatibility of anisotropy and material frame indifference of a rigid heat conductor is investigated. For this purpose, the deformation gradient is introduced into the domain of the constitutive mapping. Because of the ... More
Non-Equilibrium Thermodynamics and Stochasticity, A Phenomenological Look on Jarzynki's EqualityMar 07 2016The theory of phenomenological Non-equilibrium Thermodynamics is extended by includimg stochastic processes in order to account for recently derived thermodynamical relations such as the Jarzynski equality. Four phenomenological axioms are postulated ... More
Photons in a BallOct 15 2015Dec 16 2015The electromagnetic field inside a spherical cavity of large radius R is considered in the presence of stationary charge and current densities. R provides infra-red regularization while maintaining gauge invariance. The quantum ground state of physical ... More
Darwinian Adverse SelectionJul 14 2015We develop a model to study the role of rationality in economics and biology. The model's agents differ continuously in their ability to make rational choices. The agents' objective is to ensure their individual survival over time or, equivalently, to ... More
Flat bands and long range Coulomb interactions: conducting or insulating?Jul 23 2014Dispersionless (flat) electronic bands are investigated regarding their conductance properties. Due to "caging" of carriers these bands are usually insulating at partial filling, at least on the non-interacting level. Considering the specific example ... More
The initial value problem as it relates to numerical relativityOct 12 2016Spacetime is foliated by spatial hypersurfaces in the 3+1 split of General Relativity. The initial value problem then consists of specifying initial data for all relevant fields on one such a spatial hypersurface. These fields are the 3-metric and extrinsic ... More
The Linearization of Pairwise Markov NetworksFeb 17 2015Belief Propagation (BP) allows to approximate exact probabilistic inference in graphical models, such as Markov networks (also called Markov random fields, or undirected graphical models). However, no exact convergence guarantees for BP are known, in ... More
Semi-Supervised Learning with HeterophilyDec 09 2014We propose a novel linear semi-supervised learning formulation that is derived from a solid probabilistic framework: belief propagation. We show that our formulation generalizes a number of label propagation algorithms described in the literature by allowing ... More
New Physics Interpretations of the B-->K*mu+mu- AnomalyMay 20 2014This talk discusses possible new physics interpretations of recent experimental results on the B-->K*mu+mu- decay that show a discrepancy with the Standard Model predictions. A model independent analysis that takes into account all the relevant observables ... More
On the number of soft quanta in classical field configurationsJun 26 2013Aug 26 2013A crucial ingredient in the large-N quantum portrait of black holes proposed by Dvali and Gomez is the estimate of the number of soft quanta that make up the classical gravitational field. It is argued here that the coherent state formalism provides a ... More
Temperatures of Fragment Kinetic Energy SpectraNov 28 1994Nov 29 1994Multifragmentation reactions without large compression in the initial state (proton-induced reactions, reverse-kinematics, projectile fragmentation) are examined, and it is verified quantitatively that the high temperatures obtained from fragment kinetic ... More
Particle-particle correlations and the space-time structure of heavy ion collisionsFeb 26 1993The present status of the use of two-particle intensity interferometry as a diagnostic tool to study the space-time dynamics of intermediate energy heavy ion collisions is examined. Calculations for the two-proton and two-pion correlation functions are ... More
On Designs for Recursive Least Squares Residuals to Detect AlternativesJun 28 2016Linear regression models are checked by a lack-of-fit (LOF) test to be sure that the model is at least approximatively true. In many practical cases data are sampled sequentially. Such a situation appears in industrial production when goods are produced ... More
Janus-Facedness of the Pion: Analytic Instantaneous Bethe-Salpeter ModelsJul 08 2016Inversion enables the construction of interaction potentials underlying - under fortunate circumstances even analytic - instantaneous Bethe-Salpeter descriptions of all lightest pseudoscalar mesons as quark-antiquark bound states of Goldstone-boson nature. ... More
Hawking radiation is corpuscularJun 06 2016Jun 29 2016The total number of Hawking quanta emitted during the evaporation of a Schwarzschild black hole is proportional to the square of the initial mass or, equivalently, to the Bekenstein entropy. This simple, but little appreciated, fact is interpreted in ... More
Generating functional for gravitational null initial dataMay 15 2019A field theory on a three-dimensional manifold is introduced, whose field equations are the constraint equations for general relativity on a three-dimensional null hypersurface. The underlying boundary action consists of two copies of the dressed Chern-Simons ... More
Fluxon-induced losses in niobium thin-film cavities revisitedApr 15 2019Long standing data from niobium thin film accelerating cavities will be revisited and analyzed by the two-fluid model of RF superconductivity. Firstly, the applicability and limitation of this model are explored using data of the BCS surface resistance ... More
New boundary variables for classical and quantum gravity on a null surfaceApr 24 2017The covariant Hamiltonian formulation for general relativity is studied in terms of self-dual variables on a manifold with an internal and lightlike boundary. At this inner boundary, new canonical variables appear: a spinor and a spinor-valued two-form ... More
New ISR Cross Section Results on KS KL pi0 and KS KL pi0 pi0 From BABARNov 25 2016We present preliminary measurements of the cross sections for e+e- --> KS KL pi0 and KS KL pi0 pi0 obtained using the technique of Initial State Radiation with 469 fb^-1 of e+e- collision data collected with the BABAR detector at or near the Upsilon(4S) ... More
Accelerated Landweber methods based on co-dilated orthogonal polynomialsJun 09 2012Dec 20 2012In this article, we introduce and study accelerated Landweber methods for linear ill-posed problems obtained by an alteration of the coefficients in the three-term recurrence relation of the \nu-methods. The residual polynomials of the semi-iterative ... More
The Burnside Ring and Equivariant Stable Cohomotopy for Infinite GroupsApr 04 2005Jul 12 2005After we have given a survey on the Burnside ring of a finite group, we discuss and analyze various extensions of this notion to infinite (discrete) groups. The first three are the finite-G-set-version, the inverse-limit-version and the covariant Burnside ... More
The Segal Conjecture for Infinite GroupsJan 26 2019We formulate and prove a version of the Segal Conjecture for infinite groups. For finite groups it reduces to the original version. The condition that G is finite is replaced in our setting by the assumption that there exists a finite model for the classifying ... More
Shadows of graphical mean curvature flowApr 18 2016We consider mean curvature flow of an initial surface that is the graph of a function over some domain of definition in $R^n$. If the graph is not complete then we impose a constant Dirichlet boundary condition at the boundary of the surface. We establish ... More
K- and L-theory of the semi-direct product of the discrete 3-dimensional Heisenberg group by Z/4Dec 08 2004Sep 11 2005We compute the group homology, the topological K-theory of the reduced C^*-algebra, the algebraic K-theory and the algebraic L-theory of the group ring of the semi-direct product of the three-dimensional discrete Heisenberg group by Z/4. These computations ... More
Difference Problems and Differential ProblemsDec 03 2007We state some elementary problems concerning the relation between difference calculus and differential calculus, and we try to convince the reader that, in spite of the simplicity of the statements, a solution of these problems would be a significant ... More
The Poincaré series of some special quasihomogeneous surface singularitiesApr 13 2000Sep 26 2001In the author's paper ''Poincar\'{e} series and monodromy of a two-dimensional quasihomogeneous hypersurface singularity'' a relation is proved between the Poincar\'{e} series of the coordinate algebra of a two-dimensional quasihomogeneous isolated hypersurface ... More
Asymptotic optimality of scalar Gersho quantizersMar 16 2012Jun 21 2013In his famous paper [7] Gersho stressed that the codecells of optimal quantizers asymptotically make an equal contribution to the distortion of the quantizer. Motivated by this fact, we investigate in this paper quantizers in the scalar case, where each ... More
On a Fair Copy of Riemann's 1859 Publication Created by Alfred ClebschDec 09 2015Dec 16 2015We will verify that the fair copy "Ueber die Anzahl der Primzahlen unter einer gegebenen Gr\"osse" found in Riemann's Nachlass is not in Riemann's hand. Further, we will show that this paper was written by Alfred Clebsch and that it was used after Clebsch's ... More
Presentations of symbolic dynamical systems by labelled directed graphs (Notes for a "mini-cours", SDA2, Paris 4-5 October 2007)Sep 10 2012We develop some aspects of a general theory of presentations of subshifts by labelled directed graphs, in particular by compact graphs. Also considered are synchronization properties of subshifts that lead to presentations by countable graphs.
Progress and problems in quantum gravityDec 01 2005From the point of view of an uncompromising field theorist quantum gravity is beset with serious technical and, above all, conceptual problems with regard especially to the meaning of genuine "physical" observables. This situation is not really improved ... More
Search for Single-Top Production at CDFMay 21 2007This article reports on recent searches for single-top-quark production by the CDF collaboration at the Tevatron using a data set that corresponds to an integrated luminosity of 955 pb^-1. Three different analyses techniques are employed, one using likelihood ... More
Stability and Dynamic of strain mediated Adatom Superlattices on Cu<111>May 11 2012Substrate strain mediated adatom density distributions have been calculated for Cu<111> surfaces. Complemented by Monte Carlo calculations a hexagonal close packaged adatom superlattice in a coverage range up to 0.045 ML is derived. Conditions for the ... More
Strain mediated interaction of adatom dimersJan 16 2013Oct 25 2016An earlier model for substrate strain mediated interactions between monomer adatoms is extended to the interaction of monomers with dimers and the interaction of dimers. While monomers (sitting on high symmetric sites) are supposed to create isotropic ... More
Fayet-Iliopoulos Potentials from Four-FoldsSep 19 1997We show how certain non-perturbative superpotentials W, which are the two-dimensional analogs of the Seiberg-Witten prepotential in 4d, can be computed via geometric engineering from 4-folds. We analyze an explicit example for which the relevant compact ... More
Analytic Quest for Confining Interaction Kernels in Instantaneous Bethe-Salpeter EquationsOct 05 2010The Salpeter equation, a standard tool in hadron physics, constitutes a well-defined three-dimensional approximation to the Bethe-Salpeter formalism for the description of bound states within quantum field theories. However, if confinement is implemented ... More
Bethe-Salpeter Equations with Instantaneous Confinement: Establishing Stability of Bound StatesAug 08 2010Salpeter equations with potential functions rising to infinity in configuration space do not automatically predict stable bound states. For this to happen, also the Lorentz behaviour of the involved Bethe-Salpeter kernels is crucial. At least for interaction ... More
General (anti-)commutators of gamma matricesNov 09 2007Commutators and anticommutators of gamma matrices with arbitrary numbers of (antisymmetrized) indices are derived.
The Method of Geodesic Expansions and its Application to the Semiclassical Sum over Immersed ManifoldsSep 11 1997Dec 06 1997The method of geodesic expansions is systematically explained. Based on the Haar measures of the group of geodesic expansions the semiclassical sum over immersed manifolds is constructed. Gauge fixing is performed via the Faddeev Popov method.
The Polyakov Loop of Anti-symmetric Representations as a Quantum Impurity ModelDec 09 2010Jan 21 2011The Polyakov loop of an operator in the anti-symmetric representation in N=4 SYM theory on spacial R^3 is calculated, to leading order in 1/N and at large 't Hooft coupling, by solving the saddle point equations of the corresponding quantum impurity model. ... More
Searching for the Scalar GlueballMay 07 2008Existence of gluonic resonances is among the early expectations of QCD. Today, QCD calculations predict the lightest glueball to be a scalar state with mass within a range of about 900-1700 MeV but there is no consensus about its experimental evidence. ... More