Results for "Stephan Diehl"

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Sketches and Diagrams in PracticeJun 28 2017Sketches and diagrams play an important role in the daily work of software developers. In this paper, we investigate the use of sketches and diagrams in software engineering practice. To this end, we used both quantitative and qualitative methods. We ... More
SOTorrent: Reconstructing and Analyzing the Evolution of Stack Overflow PostsMar 20 2018May 07 2018Stack Overflow (SO) is the most popular question-and-answer website for software developers, providing a large amount of code snippets and free-form text on a wide variety of topics. Like other software artifacts, questions and answers on SO evolve over ... More
Navigate, Understand, Communicate: How Developers Locate Performance BugsJun 30 2017Background: Performance bugs can lead to severe issues regarding computation efficiency, power consumption, and user experience. Locating these bugs is a difficult task because developers have to judge for every costly operation whether runtime is consumed ... More
Usage and Attribution of Stack Overflow Code Snippets in GitHub ProjectsFeb 08 2018Stack Overflow (SO) is the largest Q&A website for software developers, providing a huge amount of copyable code snippets. Using those snippets raises maintenance and legal issues. SO's license (CC BY-SA 3.0) requires attribution, i.e., referencing the ... More
Towards a Theory of Software Development ExpertiseJul 16 2018Nov 04 2018Software development includes diverse tasks such as implementing new features, analyzing requirements, and fixing bugs. Being an expert in those tasks requires a certain set of skills, knowledge, and experience. Several studies investigated individual ... More
Usage and Attribution of Stack Overflow Code Snippets in GitHub ProjectsFeb 08 2018Sep 21 2018Stack Overflow (SO) is the most popular question-and-answer website for software developers, providing a large amount of copyable code snippets. Using those snippets raises maintenance and legal issues. SO's license (CC BY-SA 3.0) requires attribution, ... More
Worse Than Spam: Issues In Sampling Software DevelopersJul 04 2017Background: Reaching out to professional software developers is a crucial part of empirical software engineering research. One important method to investigate the state of practice is survey research. As drawing a random sample of professional software ... More
Attribution Required: Stack Overflow Code Snippets in GitHub ProjectsJul 03 2017Stack Overflow (SO) is the largest Q&A website for developers, providing a huge amount of copyable code snippets. Using these snippets raises various maintenance and legal issues. The SO license requires attribution, i.e., referencing the original question ... More
Round-Trip Sketches: Supporting the Lifecycle of Software Development Sketches from Analog to Digital and BackAug 05 2017Sketching is an important activity for understanding, designing, and communicating different aspects of software systems such as their requirements or architecture. Often, sketches start on paper or whiteboards, are revised, and may evolve into a digital ... More
SOTorrent: Studying the Origin, Evolution, and Usage of Stack Overflow Code SnippetsSep 08 2018Stack Overflow (SO) is the most popular question-and-answer website for software developers, providing a large amount of copyable code snippets. Like other software artifacts, code on SO evolves over time, for example when bugs are fixed or APIs are updated ... More
SOTorrent: Studying the Origin, Evolution, and Usage of Stack Overflow Code SnippetsSep 08 2018Mar 09 2019Stack Overflow (SO) is the most popular question-and-answer website for software developers, providing a large amount of copyable code snippets. Like other software artifacts, code on SO evolves over time, for example when bugs are fixed or APIs are updated ... More
Linking Sketches and Diagrams to Source Code ArtifactsJun 29 2017Recent studies have shown that sketches and diagrams play an important role in the daily work of software developers. If these visual artifacts are archived, they are often detached from the source code they document, because there is no adequate tool ... More
Rotation invariants of two dimensional curves based on iterated integralsMay 29 2013We introduce a novel class of rotation invariants of two dimensional curves based on iterated integrals. The invariants we present are in some sense complete and we describe an algorithm to calculate them, giving explicit computations up to order six. ... More
Generalized parton distributions from form factorsOct 17 2005The electromagnetic nucleon form factors provide constraints on generalized quark distributions. Key results of the study presented here are a strong dependence of the average impact parameter of quarks on their longitudinal momentum fraction, a striking ... More
From form factors to generalized parton distributionsJun 25 2013I present an extraction of generalized parton distributions from selected data on the electromagnetic nucleon form factors. The extracted distributions can in particular be used to quantify the contribution to the proton spin from the total angular momentum ... More
Spin and other aspects of generalized parton distributionsJan 14 2002I discuss how generalized parton distribution probe various aspects of QCD bound states. Topics include the interplay between transverse and longitudinal structure, quantum mechanical interference, orbital angular momentum, helicity flip, and higher-spin ... More
Azimuthal angles in diffractive ep collisionsOct 21 1996Sep 15 1997We investigate azimuthal correlations in deep inelastic diffractive scattering, e + p -> e + \tilde{p} + X. The dependence of the ep cross section on the angle between the lepton plane and some direction in the hadronic final state can be written in a ... More
Diffractive production of dijets at HERAJul 29 1994Aug 18 1994We investigate the production of a quark-antiquark pair in diffractive photon- proton scattering, approximating soft pomeron exchange by the exchange of two nonperturbative gluons. In deep inelastic scattering at HERA, events with two jets and the scattered ... More
News from Cosmic Gamma-ray Line ObservationsNov 28 2016The measurement of gamma rays at MeV energies from cosmic radioactivities is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and how they shape objects such as massive stars and supernova explosions. Additionally, the ... More
Cosmic Gamma-Ray SpectroscopyJul 16 2013Gamma-ray instrumentation for astronomical spectroscopy consists of multiple-interaction detectors in space combined with sophisticated post-processing of detector events on ground. Spectral signatures in the MeV regime originate from transitions in the ... More
Introduction to Astronomy with RadioactivityJul 13 2010In the late nineteenth century, Antoine Henri Becquerel discovered radioactivity and thus the physics of weak interactions, well before atomic and quantum physics was known. The different types of radioactive decay, alpha, beta, and gamma decay, all are ... More
The Evolution of Stack Overflow Posts: Reconstruction and AnalysisNov 02 2018Stack Overflow (SO) is the most popular question-and-answer website for software developers, providing a large amount of code snippets and free-form text on a wide variety of topics. Like other software artifacts, questions and answers on SO evolve over ... More
(No) Influence of Continuous Integration on the Commit Activity in GitHub ProjectsFeb 23 2018Sep 14 2018A core goal of Continuous Integration (CI) is to make small incremental changes to software projects, which are integrated frequently into a mainline repository or branch. This paper presents an empirical study that investigates if developers adjust their ... More
Non-Equilibrium Universality in the Heating Dynamics of Interacting Luttinger LiquidsApr 14 2014Jun 02 2016We establish a new non-equilibrium scaling regime in the short time evolution of one-dimensional interacting open quantum systems subject to a generic heating mechanism. This dynamical regime is characterized by uncompensated phonon production and a super-diffusive, ... More
Absence of Criticality in the Phase Transitions of Open Floquet SystemsJul 05 2018Floquet systems hold the promise to realize novel phases of matter without equilibrium counterpart. The coupling to a bath can stabilize a stationary state at finite energy density. We address here the nature of phase transitions in such systems at rapid ... More
The inverse problem for rough controlled differential equationsJul 10 2014Nov 14 2014We provide a necessary and sufficient condition for a rough control driving a differential equation to be reconstructable, to some order, from observing the resulting controlled evolution. Physical examples and applications in stochastic filtering and ... More
Angular correlations in the double Drell-Yan processOct 19 2012Dec 19 2012We study the impact of parton correlations on the double Drell-Yan process, i.e. on the production of two electroweak gauge bosons by double parton scattering in a single proton-proton collision. Spin correlations between two partons in a proton are shown ... More
Theoretical considerations on multiparton interactions in QCDFeb 15 2011Mar 29 2011We investigate several ingredients for a theory of multiple hard scattering in hadron-hadron collisions. Issues discussed include the space-time structure of multiple interactions, their power behavior, spin and color correlations, interference terms, ... More
The transverse spin structure of the pion at short distancesMar 22 2010May 07 2010We study the form factors of the quark tensor currents in the pion at large squared momentum transfer Q^2. It turns out that certain form factors can be evaluated using collinear factorization, whereas others receive important contributions from the end-point ... More
On the analysis of lepton scattering on longitudinally or transversely polarized protonsMar 02 2005We discuss polarized lepton-proton scattering with special emphasis on the difference between target polarization defined relative to the lepton beam or to the virtual photon direction. In particular, this difference influences azimuthal distributions ... More
Anomalous triple gauge couplings in e+ e- -> W+ W- and "optimal" strategies for their measurementJan 31 1997We show how one can measure anomalous WWZ- and WWgamma-couplings with minimal statistical error using integrated observables, without having to assume that the anomalous couplings are small. We propose a parametrisation of these couplings which is well ... More
Functional Integral for Ultracold Fermionic AtomsOct 15 2005Feb 07 2007We develop a functional integral formalism for ultracold gases of fermionic atoms. It describes the BEC - BCS crossover and involves both atom and molecule fields. Beyond mean field theory we include the fluctuations of the molecule field by the solution ... More
Dispersion representations for hard exclusive processesJul 03 2007Several hard exclusive scattering processes admit a description in terms of generalized parton distributions and perturbative hard-scattering kernels. Both the physical amplitude and the hard-scattering kernels fulfill dispersion relations. We give a ... More
Dynamic surface critical behavior of systems with conserved bulk order parameter: Detailed RG analysis of the semi-infinite extensions of model B with and without nonconservative surface termsOct 11 1994The dynamic surface critical behavior of macroscopic systems whose dynamic bulk critical behavior is described by model $B$ is investigated. The semi-infinite extensions of bulk model $B$ introduced in a previous treatment [Phys. Rev. B 49, 2846 (1994)] ... More
Transversity Distribution Does Not Contribute to Hard Exclusive Electroproduction of MesonsJul 26 1999We show that in hard exclusive electroproduction, ep-->eVp, the leading-twist hard-scattering coefficient for the production of a transversely polarized vector meson V vanishes to all orders of perturbation theory. This implies that this process cannot ... More
Introduction to Physical Implementations of Quantum Information ProcessingMar 01 2013This was a contribution to the lecture notes on the 44th IFF Spring School held at Forschungszentrum J\"ulich in 2013 on "Quantum Information Processing". The school as a whole had a strong focus on solid state systems. It was the purpose of this contribution ... More
Recent Progress in Lattice QCDJan 09 2013Recent progress in Lattice QCD is highlighted. After a brief introduction to the methodology of lattice computations the presentation focuses on three main topics: Hadron Spectroscopy, Hadron Structure and Lattice Flavor Physics. In each case a summary ... More
Gauge action improvement and smearingSep 23 2004Dec 28 2005The effect of repeatedly smearing SU(3) gauge configurations is investigated. Six gauge actions (Wilson, Symanzik, Iwasaki, DBW2, Beinlich-Karsch-Laermann, Langfeld; combined with a direct SU(3)-overrelaxation step) and three smearings (APE, HYP, EXP) ... More
Aspects of Quasi-Phasestructure of the Schwinger Model on a Cylinder with Broken Chiral SymmetryMay 19 1998Oct 05 1998We consider the N_f-flavour Schwinger Model on a thermal cylinder of circumference $\beta=1/T$ and of finite spatial length $L$. On the boundaries $x^1=0$ and $x^1=L$ the fields are subject to an element of a one-dimensional class of bag-inspired boundary ... More
Minimal even sets of nodesOct 20 1997We extend some results on even sets of nodes which have been proved for surfaces up to degree 6 to surfaces up to degree 10. In particular, we give a formula for the minimal cardinality of a nonempty even set of nodes.
A Projective Surface of Degree Eight with 168 NodesJul 19 1995The estimate for the maximal number of ordinary double points of a projective surface of degree eight is improved to $168\leq\mu(8)\leq 174$ by constructing a projective surface of degree eight with 168 nodes.
Degenerations of ideal hyperbolic triangulationsAug 16 2005Jun 07 2011Let M be a cusped 3-manifold, and let T be an ideal triangulation of M. The deformation variety D(T), a subset of which parameterises (incomplete) hyperbolic structures obtained on M using T, is defined and compactified by adding certain projective classes ... More
Distribution Functionals for Hard Particles in N DimensionsFeb 15 2015The current article completes our investigation of the hard-particle interaction by determining their distribution functionals. Beginning with a short review of the perturbation expansion of the free-energy functional, we derive two representations of ... More
The MaxEnt extension of a quantum Gibbs family, convex geometry and geodesicsOct 31 2014We discuss methods to analyze a quantum Gibbs family in the ultra-cold regime where the norm closure of the Gibbs family fails due to discontinuities of the maximum-entropy inference. The current discussion of maximum-entropy inference and irreducible ... More
On distances and metrics in discrete ordered setsJun 30 2013Discrete partially ordered sets can be turned into distance spaces in several ways. The distance functions may or may not satisfy the triangle inequality, and restriction of the distance to finite chains may or may not coincide with the natural, difference-of-height ... More
Feasibility of giant fiber-optic gyroscopesJan 04 2013Mar 07 2013The availability of long-distance, underground fiber-optic links opens a perspective of implementing interferometric fiber-optic gyroscopes embracing very large areas. We discuss the potential sensitivity, some disturbances and approaches to overcome ... More
Elliptic curves with square-free $Δ$Mar 05 2015Jun 09 2015Under the Riemann Hypothesis for Dirichlet L-functions, we improve on the error term in a smoothed version of an estimate for the density of elliptic curves with square-free $\Delta=D/16$, where D is the discriminant, by T.D. Browning and the author. ... More
The number of fixed points of Wilf's partition involutionJul 24 2013Wilf partitions are partitions of an integer $n$ in which all nonzero multiplicities are distinct. On his webpage, the late Herbert Wilf posed the problem to find "any interesting theorems" about the number f(n) of those partitions. Recently, Fill, Janson ... More
On the divisor class group of double solidsSep 28 1998Sep 29 1998For a double solid $V\to P_3(C)$ branched over a surface $B\subset P_3(C)$ with only ordinary nodes as singularities, we give a set of generators of the divisor class group $Pic(\tilde{V}})$ in terms of contact surfaces of $B$ with only superisolated ... More
Addendum to "On the $p^λ$ problem"Dec 19 2005We prove that the conditions $\lambda<5/19$ and $L\le T^{1/2}$ in Theorems 3 and 4 of our recent paper "On the $p^{\lambda}$ problem" can be omitted.
On the $p^λ$ problemDec 19 2005We deal with the distribution of the fractional parts of $p^{\lambda}$, $p$ running over the prime numbers and $\lambda$ being a fixed real number lying in the interval $(0,1)$. Roughly speaking, we study the following question: Given a real $\theta$, ... More
Pathwise construction of tree-valued Fleming-Viot processesApr 14 2014Dec 27 2017In a random complete and separable metric space that we call the lookdown space, we encode the genealogical distances between all individuals ever alive in a lookdown model with simultaneous multiple reproduction events. We construct families of probability ... More
Towards a characterization of Markov processes enjoying the time-inversion propertyJun 01 2005Apr 26 2007We give a necessary and sufficient condition for a homogeneous Markov process taking values in $\R^n$ to enjoy the time-inversion property of degree $\alpha$. The condition sets the shape for the semigroup densities of the process and allows to further ... More
Piecewise deterministic Markov processes driven by scalar conservation lawsJan 29 2019We investigate piecewise deterministic Markov processes (PDMP), where the deterministic dynamics follows a scalar conservation law and random jumps in the system are characterized by changes in the flux function. We show under which assumptions we can ... More
Operator systems and convex sets with many normal conesJun 13 2016Sep 13 2016The state space of an operator system of $n$-by-$n$ matrices has, in a sense, many normal cones. Merely this convex geometrical property implies smoothness qualities and a clustering property of exposed faces. The latter holds since each exposed face ... More
Quantum Convex SupportJan 16 2011Sep 08 2011Convex support, the mean values of a set of random variables, is central in information theory and statistics. Equally central in quantum information theory are mean values of a set of observables in a finite-dimensional C*-algebra A, which we call (quantum) ... More
A Note on Touching Cones and FacesOct 14 2010May 03 2011We study touching cones of a (not necessarily closed) convex set in a finitedimensional real Euclidean vector space and we draw relationships to other concepts in Convex Geometry. Exposed faces correspond to normal cones by an antitone lattice isomorphism. ... More
Tree lengths for general $Λ$-coalescents and the asymptotic site frequency spectrum around the Bolthausen-Sznitman coalescentApr 03 2018Jan 22 2019We study tree lengths in $\Lambda$-coalescents without a dust component from a sample of $n$ individuals. For the total length of all branches and the total length of all external branches we present laws of large numbers in full generality. The other ... More
A representation for exchangeable coalescent trees and generalized tree-valued Fleming-Viot processesAug 29 2016We show that every exchangeable random semi-ultrametric on the integers can be obtained by sampling an iid sequence from a random marked metric measure space and adding the marks to the distances. We use this representation to define tree-valued Fleming-Viot ... More
Anomalous electronic conductance in quasicrystalsJul 27 1999Jul 31 1999Generic quantum interference effects occuring in 1D-quasicrystals are reviewed with emphasis on the joint effect of phason disorder on electronic localization and propagation modes. In close conjunction with properties of real materials, the contributions ... More
The Lorentz group and its finite field analogues: local isomorphism and approximationMay 08 2008Aug 04 2008Finite Lorentz groups acting on 4-dimensional vector spaces coordinatized by finite fields with a prime number of elements are represented as homomorphic images of countable, rational subgroups of the Lorentz group acting on real 4-dimensional space-time. ... More
Tackling master equations with a flux loop transformOct 25 2007Feb 21 2008A procedure is introduced which allows to represent the dynamics of a non-equilibrium system violating detailed balance by its steady state loop fluxes. It is shown that detailed balance is restored in this representation, such that the non-equilibrium ... More
Heavy Quark Physics on the LatticeDec 16 1996We illustrate the current status of heavy quark physics on the lattice. Special emphasis is paid to the question of systematic uncertainties and to the connection of lattice computations to continuum physics. Latest results are presented and discussed ... More
A Steinberg Cross-Section for Non-Connected Affine Kac-Moody GroupsJan 16 2004We generalise the concept of a Steinberg cross-section to non-connected Kac-Moody group. As in the connected case, which was treated by G. Br\"uchert, a quotient map w.r.t the conjugacy action exists only on a certain submonoid of the Kac-Moody group. ... More
Lattice QCD data versus Chiral Perturbation Theory: the case of $M_π$Sep 26 2002Sep 27 2002I present a selection of recent lattice data by major collaborations for the pseudo-Goldstone boson masses in full ($N_f=2$) QCD, where the valence quarks are chosen exactly degenerate with the sea quarks. At least the more chiral points should be consistent ... More
Simple check of the vacuum structure in full QCD lattice simulationsAug 13 2001Given the increasing availability of lattice data for (unquenched) QCD with $N_f=2$, it is worth while to check whether the generated vacuum significantly deviates from the quenched one. I discuss a specific attempt to do this on the basis of topological ... More
Study of the Leutwyler-Smilga regimes: Lessons for full QCD simulationsOct 22 2000Nov 07 2000Some key points out of my recent study of the characteristic features of the small ($x \ll 1$), intermediate ($x \simeq 1$) and large ($x \gg 1$) Leutwyler-Smilga regimes for QCD-type theories in a finite volume ($x = V \Sigma m$) are presented, and a ... More
Theoretical Aspects of Topologically Unquenched QCDSep 08 1999I give an outline of my proposal to take the QCD functional determinant in lattice simulations partially into account: The determinant is split into two factors, the factor referring to a standard background in each topological sector is kept exactly, ... More
Best-First Surface RealizationMay 06 1996Current work in surface realization concentrates on the use of general, abstract algorithms that interpret large, reversible grammars. Only little attention has been paid so far to the many small and simple applications that require coverage of a small ... More
Remarks on antichains in the causality order of space-timeJun 20 2012Jul 07 2012The two closely related Lorentz-invariant partial orders of space-time are distinguished with respect to their maximal chains, the existence of antichain cutsets and the possibility of grading. World lines of particles with or without mass are the maximal ... More
The large sieve with square norm moduli in Z[i]Nov 08 2015Jun 07 2016We prove a large sieve inequality for square norm moduli in Z[i].
Pathwise construction of tree-valued Fleming-Viot processesApr 14 2014Aug 28 2016In a random complete and separable metric space that we call the lookdown space, we encode the genealogical distances between all individuals ever alive in a lookdown model with simultaneous multiple reproduction events. We construct families of probability ... More
The Neutron and the Universe - History of a RelationshipMay 11 2012We discuss selected topics in the field of particle- and astrophysics with neutrons. They have a direct link with our understanding of the history of the Universe and are related to recent, ongoing or future measurements. They deal with the structure ... More
The Puzzle of Neutron LifetimeFeb 01 2009Mar 06 2009In this paper we review the role of the neutron lifetime and discuss the present status of measurements. In view of the large discrepancy observed by the two most precise individual measurements so far we describe the different techniques and point out ... More
Heavy Baryons - Different Facets of Experimental resultsMar 10 1999This paper reviews the experimental status of heavy baryons. It covers the aspec ts of production, spectroscopy and decay presenting recent results obtained in this fi eld. It closes with an outlook on further work on and with heavy baryons and their ... More
An A(oo)-structure on the cohomology ring of the symmetric group Sp with coefficients in FpFeb 01 2013Let p be a prime. Let FpSp be the group algebra of the symmetric group over the finite field Fp with |Fp|=p$. Let Fp be the trivial FpSp-module. We present a projective resolution PRes Fp of the module Fp and equip the Yoneda algebra Ext(Fp,Fp) with an ... More
Character varieties of mutative 3--manifoldsJun 03 2003Apr 06 2004We describe a birational map between subvarieties in the character varieties of mutative 3-manifolds. By studying the birational map, one can decide in certain circumstances whether a mutation surface is detected by an ideal point of the character variety. ... More
On McMillan's theorem about uniquely decipherable codesJun 19 2008Jun 21 2008Karush's proof of McMillan's theorem is recast as an argument involving polynomials with non-commuting indeterminates certain evaluations of which yield the Kraft sums of codes, proving a strengthened version of McMillan's theorem.
On CM values of Borcherds products and harmonic weak Maass forms of weight oneAug 11 2012We show that the values of Borcherds products on Shimura varieties of orthogonal type at certain CM points are given in terms of coefficients of the holomorphic part of weight one harmonic weak Maass forms. Furthermore, we investigate the arithmetic properties ... More
On equivariant homotopy theory for model categoriesAug 04 2013Feb 16 2016We introduce and compare two approaches to equivariant homotopy theory in a topological or ordinary Quillen model category. For the topological model category of spaces, we generalize Piacenza's result that the categories of topological presheaves indexed ... More
Taut Submanifolds and FoliationsDec 27 2011Jan 03 2012We give an equivalent description of taut submanifolds of complete Riemannian manifolds as exactly those submanifolds whose normal exponential map has the property that every preimage of a point is a union of submanifolds. It turns out that every taut ... More
$α_s(μ)$ from $M_{χ_{0c(0b)}}-M_{η_{c(b)}}$@N2LODec 19 2018This note complements and clarifies the results obtained in the original paper {\it QCD Parameters Correlations from Heavy Quarkonia} [1] where, here, we present a more detailed discussion of the \alpha_s-results obtained @ N2LO at two different subtraction ... More
Numerical evaluation of multi-loop integralsNov 28 2018We present updates on the development of pySecDec, a toolbox to numerically evaluate parameter integrals in the context of dimensional regularization. We discuss difficulties with loop integrals in the special kinematic condition where the squared momentum ... More
Properties of the fixed ring of a preprojective algebraMay 08 2018Oct 24 2018For a finite group acting on a polynomial ring, the Chevalley-Shephard-Todd Theorem proves that the fixed subring is isomorphic to a polynomial ring if and only if the group is generated by pseudo-reflections. In recent years, progress was made in work ... More
The structure of minimal surfaces in CAT(0) spacesAug 20 2018We prove that a minimal disc in a CAT(0) space is a local embedding away from a finite set of "branch points". On the way we establish several basic properties of minimal surfaces: monotonicity of area densities, density bounds, limit theorems and the ... More
CM values of regularized theta lifts and harmonic weak Maaß forms of weight oneJan 13 2017We study special values of regularized theta lifts at complex multiplication (CM) points. In particular, we show that CM values of Borcherds products can be expressed in terms of finitely many Fourier coefficients of certain harmonic weak Maa{\ss} forms ... More
Perturbed gradient flow trees and $A_\infty$-algebra structures on Morse cochain complexesNov 23 2016We elaborate on an idea of M. Abouzaid of equipping the Morse cochain complex of a smooth Morse function on a closed oriented manifold with the structure of an $A_\infty$-algebra. This is a variation on K. Fukaya's definition of Morse-$A_\infty$-categories ... More
Non-Autonomous Maximal Regularity for Forms Given by Elliptic Operators of Bounded VariationSep 28 2016We show maximal $L^p$-regularity for non-autonomous Cauchy problems provided the trace spaces are stable in some parameterized sense and the time dependence is of bounded variation. In particular, on $L^2$, we obtain for all $p \in (1,2]$ maximal $L^p$-regularity ... More
Invariance principles for tree-valued Cannings chainsAug 29 2016Feb 24 2017We consider sequences of tree-valued Markov chains that describe evolving genealogies in Cannings models, and we show their convergence in distribution to tree-valued Fleming-Viot processes. Under the conditions of M\"ohle and Sagitov, this convergence ... More
Phase Transition in the Number Partitioning ProblemJul 06 1998Sep 21 1998Number partitioning is an NP-complete problem of combinatorial optimization. A statistical mechanics analysis reveals the existence of a phase transition that separates the easy from the hard to solve instances and that reflects the pseudo-polynomiality ... More
A new perspective on the Holstein polaron problemJun 12 1996The single-polaron band structure of the Holstein model in one and two dimensions is studied using a new form of resummed strong-coupling perturbation theory. Well converged results are obtained for phonon frequencies of the order of the hopping integral ... More
Decay Constants of Heavy-Light Mesons from QCDNov 18 2015Nov 29 2015We summarize recently improved results for the pseudoscalar [1,2] and vector [3] meson decay constants and their ratios from QCD spectral sum rules where N2LO + estimate of the N3LO PT and power corrections up to d< 6 dimensions have been included in ... More
On the number of colored Birch and Tverberg partitionsAug 02 2012Dec 09 2012In 2009, Blagojevic, Matschke & Ziegler established the first tight colored Tverberg theorem, but no lower bounds for the number of colored Tverberg partitions. We develop a colored version of our previous results (2008), and we extend our results from ... More
A note on inhomogeneous foliations with sectionsOct 03 2013We give an easy example showing that sections of a singular Riemannian foliation on a simply connected space neither have to be isometric nor injectively immersed.
Test of Symmetries with Neutrons and NucleiFeb 10 2009Mar 06 2009Precision experiments at low energies probing weak interaction are a very promising and complementary tool for investigating the structure of the electro-weak sector of the standard model, and for searching for new phenomena revealing signs for an underlaying ... More
Lineare Rekurrenzen, Potenzreihen und ihre erzeugenden FunktionenApr 19 2007Apr 20 2007Diese kurze Einfuehrung in Theorie und Berechnung linearer Rekurrenzen versucht, eine Luecke in der Literatur zu fuellen. Zu diesem Zweck sind viele ausfuehrliche Beispiele angegeben. This short introduction to theory and usage of linear recurrences tries ... More
Dark matter constraints in the minimal and nonminimal SUSY standard modelSep 05 1997Feb 24 1998We determine the allowed parameter space and the particle spectra of the minimal SUSY standard model (MSSM) and nonminimal SUSY standard model (NMSSM) imposing correct electroweak gauge-symmetry breaking and recent experimental constraints. The parameters ... More
A primer on A-infinity-algebras and their Hochschild homologyJan 15 2016We present an elementary and self-contained construction of $A_\infty$-algebras, $A_\infty$-bimodules and their Hochschild homology and cohomology groups. In addition, we discuss the cup product in Hochschild cohomology and the spectral sequence of the ... More
Maximal Regularity: Positive Counterexamples on UMD-Banach Lattices and Exact Intervals for the Negative Solution of the Extrapolation ProblemNov 16 2014Using methods from Banach space theory, we prove two new structural results on maximal regularity. The first says that there exist positive analytic semigroups on UMD-Banach lattices, namely $\ell_p(\ell_q)$ for $p \neq q \in (1, \infty)$, without maximal ... More
Maximum-entropy inference and inverse continuity of the numerical rangeFeb 13 2015Aug 13 2015We study the continuity of the maximum-entropy inference map for two observables in finite dimensions. We prove that the continuity is equivalent to the strong continuity of the set-valued inverse numerical range map. This gives a continuity condition ... More