Results for "Wolfgang Ackermann"

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Precise exponential decay for solutions of semilinear elliptic equations and its effect on the structure of the solution set for a real analytic nonlinearityMar 12 2015We are concerned with the properties of weak solutions of the stationary Schr\"odinger equation $-\Delta u + Vu = f(u)$, $u\in H^1(\mathbb{R}^N)\cap L^\infty(\mathbb{R}^N)$, where $V$ is H\"older continuous and $\inf V>0$. Assuming $f$ to be continuous ... More
Uncertainty Quantification for Maxwell's Eigenproblem using Isogeometric AnalysisFeb 08 2018May 30 2018The electromagnetic field distribution as well as the resonating frequency of various modes in superconducting cavities used in particle accelerators for example are sensitive to small geometry deformations. The occurring variations are motivated by measurements ... More
Uncertainty Quantification for Maxwell's Eigenproblem based on Isogeometric Analysis and Mode TrackingFeb 08 2018Mar 06 2019The electromagnetic field distribution as well as the resonating frequency of various modes in superconducting cavities used in particle accelerators for example are sensitive to small geometry deformations. The occurring variations are motivated by measurements ... More
Uncertainty Quantification for Geometry Deformations of Superconducting Cavities using Eigenvalue TrackingFeb 08 2018The electromagnetic field distribution as well as the resonating frequency of various modes in superconducting cavities are sensitive to small geometry deformations. The occurring variations are motivated by measurements of an available set of resonators ... More
Limits to the muon flux from neutralino annihilations in the Sun with the AMANDA detectorAug 24 2005A search for an excess of muon-neutrinos from neutralino annihilations in the Sun has been performed with the AMANDA-II neutrino detector using data collected in 143.7 days of live-time in 2001. No excess over the expected atmospheric neutrino background ... More
A twisted Bass-Heller-Swan decomposition for the algebraic K-theory of additive categoriesSep 05 2013Jun 01 2015We prove a twisted Bass-Heller-Swan decomposition for both the connective and the non-connective K-theory spectrum of additive categories.
Non-connective K- and Nil-spectra of additive categorieMar 06 2013Sep 04 2013We present an elementary construction of the non-connective algebraic K-theory spectrum associated to an additive category following the contracted functor approach due to Bass. It comes with a universal property that easily allows us to identify it with ... 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
Searching for New Physics with Flavor Violating ObservablesJun 04 2012In this talk, I review the status and prospects of several low energy flavor observables that are highly sensitive to New Physics effects. In particular I discuss the implications for possible New Physics in b --> s transitions coming from the recent ... More
Top Quark Cross-Section Measurements at the TevatronDec 02 2003Run II of the Tevatron collider at Fermilab is well under way and data samples larger than those of Run I are at hand. In this contribution I summarize the current status of cross-section measurements for top-quark pair production at the CDF and D0 experiments. ... More
A new numerical method to construct binary neutron star initial dataAug 05 2009We present a new numerical method for the generation of binary neutron star initial data using a method along the lines of the the Wilson-Mathews or the closely related conformal thin sandwich approach. Our method uses six different computational domains, ... More
Constructing quasi-equilibrium initial data for binary neutron stars with arbitrary spinsSep 24 2012Nov 04 2014In general neutron stars in binaries are spinning. Recently, a new quasi-equilibrium approximation that includes a rotational velocity piece for each star has been proposed to describe binary neutron stars with arbitrary rotation states in quasi-circular ... More
Comment on the paper "Electromagnetic Wave Dynamics in Matter-Wave Superradiant Scattering" by L. Deng, M.G. Payne, and E.W. HagleyOct 19 2010The paper by Deng et al. (Phys. Rev. Lett. 104, 050402 (2010)) presents an analytic theoretical description of matter-wave superradiance (Phys. Rev. Lett. 85, 4225-4228 (2000)) which claims to go beyond previous theoretical frameworks. I show here that ... More
Chiral gauge theories on the lattice without gauge fixing?Nov 30 1993We discuss two proposals for a non-perturbative formulation of chiral gauge theories on the lattice. In both cases gauge symmetry is broken by the regularization. We aim at a dynamical restoration of symmetry. If the gauge symmetry breaking is not too ... More
Limiting soft particle production and QCDNov 10 2010We present some basic elements of the treatment of particle multiplicities in jets from high energy collisions within perturbative QCD. Then we discuss the universal features of the inclusive particle spectrum for the limiting case of momentum p\to 0 ... More
Scaling and scale breaking phenomena in QCD jetsNov 12 1996The perturbative QCD approach to multiparticle production assuming Local Parton Hadron Duality (LPHD) and some recent results are discussed. Finite asymptotic scaling limits are obtained for various observables, after an appropriate rescaling, in the ... More
UNIVERSAL PROPERTIES OF ANGULAR CORRELATIONS IN QCD JETSJan 16 1995Predictions for angular correlations between an arbitrary number of partons are derived in the high energy limit. The quantities considered depend on angles and primary energy through a single variable $\epsilon$ which implies certain scaling properties ... More
On the Solvability of Magnetic Differential EquationsOct 14 2005The calculation of both resistive and ideal plasma equilibria amounts to solving a number of magnetic differential equations which are of the type $\vec {B}\cdot \nabla \Phi =s$. We apply the necessary and sufficient criterion for the existence of the ... More
Instantaneous Interaction between Charged ParticlesNov 19 2005Mar 20 2013The interaction between charged particles through quasi-static fields must occur instantaneously; otherwise a violation of the energy principle would occur. As a consequence, the instantaneous transmission of both energy and information over macroscopic ... More
Superconvergent Perturbation Method in Quantum MechanicsDec 30 1994An analogue of Kolmogorov's superconvergent perturbation theory in classical mechanics is constructed for self adjoint operators. It is different from the usual Rayleigh--Schr\"odinger perturbation theory and yields expansions for eigenvalues and eigenvectors ... More
Quantum Averaging I: Poincaré--von Zeipel is Rayleigh--SchrödingerDec 30 1994An exact analogue of the method of averaging in classical mechanics is constructed for self--adjoint operators. It is shown to be completely equivalent to the usual Rayleigh--Schr\"odinger perturbation theory but gives the sums over intermediate states ... More
Measurement of the CKM Matrix Elements |Vcb| and |Vub| at the B-factoriesJul 18 2006Recent results on inclusive and exclusive semileptonic B decays from B-factories are presented. The impact of these measurements on the determination of the CKM matrix elements |Vub| and |Vcb| is discussed.
2d quantum gravity with torsion, dilaton theory and black hole formationOct 06 2000Starting from the work of the author in 1990 with different collaborators, essential progress in 2d gravity theories has been made. Now all such theories (and not only certain special models) can be treated at the classical as well as at the quantum level. ... More
Conceptual Differential Calculus. I: First Order Local Linear AlgebraMar 16 2015Jul 23 2015We give a rigorous formulation of the intuitive idea that a differentiable map should be thesame thing as a locally, or infinitesimally, linear map: just as a linear map respects the operations of addition and multiplication by scalars ina vector space ... More
Twisting $L^2$-invariants with finite-dimensional representationsSep 30 2015Nov 18 2015We investigate how one can twist L^2-invariants such as L^2-Betti numbers and L^2-torsion with finite-dimensional representations. As a special case we assign to the universal covering of a finite connected CW-complex X together with an element phi in ... More
Weil Spaces and Weil-Lie GroupsFeb 11 2014We define Weil spaces, Weil manifolds, Weil varieties and Weil Lie groups over an arbitrary commutative base ring K (in particular, over discrete rings such as the integers), and we develop the basic theory of such spaces, leading up the definition of ... More
The identification of glueballs - further testsFeb 03 2014The indirect evidence for gluonic objects in gluon jets is recalled, more accurate tests at the LHC are possible. Estimates of gluonic and quarkonic components of scalar mesons are presented, which could be improved by further studies, in particular of ... More
Über erreichbare und baumartige unzerlegbare Darstellungen von KöchernJan 05 2014Let $A$ be a finite-dimensional algebra over an algebraically closed field. The problem of constructing indecomposable $A$-modules inductively from simple ones by means of exact sequences - called accessibility - is the starting point of the present diploma-thesis. ... More
A Global Game with Heterogenous PriorsDec 30 2013This paper relaxes the common prior assumption in the public and private information game of Morris and Shin (2000, 2004). For the generalized game, where the agent's prior expectations are heterogenous, it derives a sharp condition for the emergence ... More
Hamiltonian Path Integrals In Momentum Space Representation via White Noise TechniquesJul 16 2013The concepts of Feynman integrals in white noise analysis are used to construct the Feynman integrand for the harmonic oscillator in momentum space representation as a Hida distribution. Moreover it is shown that in a limit sense, the potential free case ... More
Jordan Geometries - an Approach by InversionsAug 27 2013Feb 17 2014Jordan geometries are defined as spaces equipped with point reflections depending on triples of points, exchanging two of the points and fixing the third. In a similar way, symmetric spaces have been defined by Loos (Symmetric Spaces I, 1969) as spaces ... More
Instantaneous Bethe-Salpeter Approach to Pseudoscalar MesonsAug 14 2013Light pseudoscalar mesons are Janus-type particles: Within quantum chromodynamics, they must be described as bound states of its fundamental degrees of freedom and as the (pseudo-) Goldstone bosons of its spontaneously broken chiral symmetry. This janiform ... More
Combinatorics of Lattice QCD at Strong CouplingNov 17 2014Thermodynamics in the strong coupling limit of lattice QCD has features which may be similar to those of continuum QCD, such as a chiral critical end point and a nuclear liquid gas transition. Here I compare the combinatorics of staggered and Wilson fermions ... More
Estimates for spectral density functions of matrices over C[Z^d]Oct 31 2013Oct 29 2014We give a polynomial bound on the spectral density function of a matrix over the complex group ring of Z^d. It yields an explicit lower bound on the Novikov-Shubin invariant associated to this matrix showing in particular that the Novikov-Shubin invariant ... More
Lie CalculusFeb 27 2017Jun 28 2017We explain that general differential calculus and Lie theory have a common foundation: Lie Calculus is differential calculus, seen from the point of view of Lie theory, by making use of the groupoid concept as link between them. Higher order theory naturally ... More
Hadron Physics from Lattice QCDMay 25 2016We sketch the basic ideas of the lattice regularization in Quantum Field Theory, the corresponding Monte Carlo simulations, and applications to Quantum Chromodynamics (QCD). This approach enables the numerical measurement of observables at the non-perturbative ... More
Simplified Bethe-Salpeter Description of Basic Pseudoscalar-Meson FeaturesJul 11 2018We assess a description of pseudoscalar mesons as pseudo-Goldstone bosons by its compatibility with some Gell-Mann-Oakes-Renner-type relation.
An Essay on the Completion of Quantum Theory. I: General SettingNov 23 2017We propose a geometric setting of the axiomatic mathematical formalism of quantum theory. Guided by the idea that understanding the mathematical structures of these axioms is of similar importance as was historically the process of understanding the axioms ... More
Second Law and Non-Equilibrium Entropy of Schottky Systems -- Doubts and VerificationJul 11 2018Meixner's historical remark in 1969 "... it can be shown that the concept of entropy in the absence of equilibrium is in fact not only questionable but that it cannot even be defined...." is investigated from today's insight. Several statements --such ... More
On a class of highly symmetric Markov-Dyck shiftsJun 06 2018Jun 07 2018A class of highly symmetric Markov-Dyck shifts is introduced. Expressions for zeta functions are derived and topological entropies are determined.
A spectral interpolation scheme on the unit sphere based on the nodes of spherical Lissajous curvesFeb 19 2018Jul 20 2018For sampling values along spherical Lissajous curves we establish a spectral interpolation and quadrature scheme on the sphere. We provide a mathematical analysis of spherical Lissajous curves and study the characteristic properties of their intersection ... More
Lehmer's Problem for arbitrary groupsJan 03 2019We consider the problem whether for a group G there exists a constant Lambda(G) > 1 such that for any (r,s)-matrix A over the integral group ring ZG the Fuglede-Kadison determinant of the G-equivariant bounded operator from L^2(G)^r to L^2(G)^s given ... More
A note on distinguished bases of singularitiesNov 18 2016Jun 12 2017For an isolated hypersurface singularity which is neither simple nor simple elliptic, it is shown that there exists a distinguished basis of vanishing cycles which contains two basis elements with an arbitrary intersection number. This implies that the ... More
Survey on Classifying Spaces for Families of SubgroupsDec 19 2003Jun 02 2004We define for a topological group G and a family of subgroups F two versions for the classifying space for the family F, the G-CW-version E_F(G) and the numerable G-space version J_F(G). They agree if G is discrete, or if G is a Lie group and each element ... More
Jordan structures and non-associative geometryJun 11 2007In this survey paper we give an overview over constructions of geometries associated to Jordan structures (algebras, triple systems and pairs), featuring analogs of these constructions with the Lie functor on the one hand and with the approach of non-commutative ... More
On the universal property of Waldhausen's K-theoryMar 06 2017In this note we show that Waldhausen's K-theory functor from Waldhausen categories to spaces has a universal property: It is the target of the "universal global Euler characteristic", in other words, the "additivization" of the functor sending a Waldhausen ... More
On compact homogeneous $\mathrm{G}_{2(2)}$-manifoldsAug 30 2018We prove that among all compact homogeneous spaces for an effective transitive action of a Lie group whose Levi subgroup has no compact simple factors, the seven-dimensional flat torus is the only one that admits an invariant torsion-free $\mathrm{G}_{2(2)}$-structure. ... More
An Additivity theorem for cobordism categoriesMay 10 2018Oct 25 2018Using methods inspired from algebraic $K$-theory, we give a new proof of the Genauer fibration sequence, relating the cobordism categories of closed manifolds with cobordism categories of manifolds with boundaries, and of the B\"okstedt-Madsen delooping ... More
A Supplement to the Classification of Flat Homogeneous Spaces of Signature (m,2)Dec 08 2013Jun 23 2015Duncan and Ihrig (1993) gave a classification of the flat homogeneous spaces of metric signature (m,2), provided that a certain condition on the development image of these spaces holds. In this note we show that this condition can be dropped, so that ... 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
Strain mediated adatom stripe morphologies on Cu<111> simulatedJul 27 2012Jan 29 2013Substrate strain mediated adatom configurations on Cu<111> surfaces have been simulated in a coverage range up to nearly 1 monolayer. Interacting adatoms occupy positions on a triangular lattice in two dimensions. The elastic interaction is taken from ... More
Strain Induced Adatom CorrelationsMar 10 2012A Born-Green-Yvon type model for adatom density correlations is combined with a model for adatom interactions mediated by the strain in elastic anisotropic substrates. The resulting nonlinear integral equation is solved numerically for coverages from ... More
The most powerful particles in the Universe: a cosmic smashMay 06 2013This year we are celebrating 101 years since the discovery of cosmic rays. They are whizzing all around the Universe, and they occur at very different energies, including the highest particle energies that exist. However, theory predicts an abrupt suppression ... More
Flavor Changing Neutral Current Processes in a SO(10) SUSY GUT with Family SymmetryOct 08 2007We report on a detailed analysis of a SO(10) SUSY GUT model of Dermisek and Raby (DR) with a D3 family symmetry. The model is completely specified in terms of only 24 parameters and is able to successfully describe both quark and lepton masses and mixings, ... 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
Dynamical modeling and the interactions with the ISMSep 22 2011This paper is a review of some of the recent modeling efforts to improve our understanding of structure formation and evolution of planetary nebulae including their interaction with the interstellar medium. New propositions have been made for the formation ... 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
Application of Microlocal Analysis to the Theory of Quantum Fields Interacting with a Gravitational FieldJan 10 1997It is explained how techniques from microlocal analysis can be used to settle some long-standing questions that arise in the study of the interaction of quantum matter fields with a classical gravitational background field.
Adiabatic Vacua and Hadamard States for Scalar Quantum Fields on Curved SpacetimeJul 19 1995Quasifree states of a linear Klein-Gordon quantum field on globally hyperbolic spacetime manifolds are considered. Using techniques from the theory of pseudodifferential operators and wavefront sets on manifolds a criterion for a state to be an Hadamard ... More
Robust Processing of Natural LanguageJul 13 1995Jul 14 1995Previous approaches to robustness in natural language processing usually treat deviant input by relaxing grammatical constraints whenever a successful analysis cannot be provided by ``normal'' means. This schema implies, that error detection always comes ... More
Parsing of Spoken Language under Time ConstraintsSep 09 1994Spoken language applications in natural dialogue settings place serious requirements on the choice of processing architecture. Especially under adverse phonetic and acoustic conditions parsing procedures have to be developed which do not only analyse ... 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
On Matrix Factorizations, Residue Pairings and Homological Mirror SymmetryMar 27 2018Apr 11 2018We argue how boundary B-type Landau-Ginzburg models based on matrix factorizations can be used to compute exact superpotentials for intersecting D-brane configurations on compact Calabi-Yau spaces. In this paper, we consider the dependence of open-string, ... More
Ladder operators for Klein-Gordon equation with scalar curvature termOct 03 2017Dec 20 2017Recently, Cardoso, Houri and Kimura constructed generalized ladder operators for massive Klein-Gordon scalar fields in space-times with conformal symmetry. Their construction requires a closed conformal Killing vector, which is also an eigenvector of ... 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
Adatom pair distribution up to half coverage: O-Pd(100)Dec 03 2017Aug 18 2018The superposition approximation allows to calculate from pair potentials pair distributions in thermal equilibrium with the Born-Green-Yvon (BGY) equation. A 2-d variant can be used to derive adatom pair distributions from arbitrary analytical pair potentials. ... More
First-principles lattice-gas Hamiltonian revisited: O-Pd(100)Oct 28 2016Nov 30 2017The methodology of deriving an adatom lattice-gas Hamiltonian (LGH) from first principles (FP) calculations is revisited. Such LGH cluster expansions compute a large set of lateral pair-, trio-, quarto interactions by solving a set of linear equations ... More
The initial value problem as it relates to numerical relativityOct 12 2016Dec 23 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
Goldstone-Type Pseudoscalar Mesons: Instantaneous Bethe-Salpeter ModelsSep 06 2016A nontrivial instantaneous variant of the Bethe-Salpeter formalism allows us to discuss massless pseudoscalar mesons from a configuration-space-potential point of view.
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
Quantum Approximate Optimization with Parallelizable GatesFeb 04 2018Mar 01 2018The quantum approximate optimization algorithm (QAOA) has been introduced as a heuristic digital quantum computing scheme to find approximate solutions of combinatorial problems with shallow circuits. We present a scheme to parallelize this approach for ... 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
L^2-Invariants from the Algebraic Point of ViewOct 31 2003We give a survey on L^2-invariants such as L^2-Betti numbers and L^2-torsion taking an algebraic point of view. We discuss their basic definitions, properties and applications to problems arising in topology, geometry, group theory and K-theory.
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
On the geometry of cohomogeneity one manifolds with positive curvatureJul 23 2007This is a survey on cohomogeneity one manifolds with positive curvature. We discuss the known examples of this type and their geometry and the functions that describe the metric. We also describe the classification of cohomogeneity one manifolds that ... More
Holonomy Groups of Complete Flat Pseudo-Riemannian Homogeneous SpacesMay 15 2012Aug 13 2012We show that a complete flat pseudo-Riemannian homogeneous manifold with non-abelian linear holonomy is of dimension at least 14. Due to an example constructed in a previous article by Oliver Baues and the author, this is a sharp bound. Also, we give ... More
Tables of prehomogeneous modules and étale modules of reductive algebraic groupsOct 22 2016This document contains tables with the classification of prehomogeneous modules for reductive algebraic groups with up to two simple factors due to Sato, Kimura and many others, as well as corresponding tables of the \'etale modules appearing in this ... 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