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Results for "Stefan Ballmer"

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Detection Prospects of Core-Collapse Supernovae with Supernova-Optimized Third-Generation Gravitational-wave DetectorsMay 31 2019We optimize the third-generation gravitational-wave detector to maximize the range to detect core-collapse supernovae. Based on three-dimensional simulations for core-collapse and the corresponding gravitational-wave waveform emitted, the corresponding ... More
Radiative Thermal Noise for Transmissive Optics in Gravitational-Wave DetectorsJul 21 2014Aug 07 2014Radiative losses have traditionally been neglected in the calculation of thermal noise of transmissive optical elements because for the most commonly used geometries they are small compared to losses due to thermal conduction. We explore the use of such ... More
Folding Gravitational-Wave InterferometersAug 05 2016The sensitivity of kilometer-scale terrestrial gravitational wave interferometers is limited by mirror coating thermal noise. We explore the effect of folding the arm cavities of such interferometers. While simple folding alone does not reduce the mirror ... More
Spectroscopic analysis of stellar mass black-hole mergers in our local universe with ground-based gravitational wave detectorsJul 26 2016Motivated by the recent discoveries of binary black-hole mergers by the Advanced Laser Interferometer Gravitational-wave Observatory (Advanced LIGO), we investigate the prospects of ground-based detectors to perform a spectroscopic analysis of signals ... More
Comparing Finesse simulations, analytical solutions and OSCAR simulations of Fabry-Perot alignment signalsJan 22 2014This document records the results of a comparison of the interferometer simulation Finesse against an analytic (MATLAB based) calculation of the alignment sensing signals of a Fabry Perot cavity. This task was started during the commissioning workshop ... More
Probing the anisotropies of a stochastic gravitational-wave background using a network of ground-based laser interferometersOct 05 2009We present a maximum-likelihood analysis for estimating the angular distribution of power in an anisotropic stochastic gravitational-wave background using ground-based laser interferometers. The standard isotropic and gravitational-wave radiometer searches ... More
Optimal Alignment Sensing of a Readout Mode Cleaner CavityOct 18 2011Critically coupled resonant optical cavities are often used as mode cleaners in optical systems to improve the signal to noise ratio (SNR) of a signal that is encoded as an amplitude modulation of a laser beam. Achieving the best SNR requires maintaining ... More
Observation of photo-thermal feed-back in a stable dual-carrier optical springJul 10 2015Sep 04 2015We report on the observation of photo-thermal feed-back in a stable dual-carrier optical spring. The optical spring is realized in a 7 cm Fabry-Perot cavity comprised of a suspended 0.4 g small end mirror and a heavy input coupler, illuminated by two ... More
A Gravitational Wave Detector with Cosmological ReachOct 02 2014Jan 13 2015Twenty years ago, construction began on the Laser Interferometer Gravitational-wave Observatory (LIGO). Advanced LIGO, with a factor of ten better design sensitivity than Initial LIGO, will begin taking data this year, and should soon make detections ... More
Optimal strategies for gravitational wave stochastic background searches in pulsar timing dataSep 03 2008Dec 16 2008A low frequency stochastic background of gravitational waves may be detected by pulsar timing experiments in the next five to ten years. Using methods developed to analyze interferometric gravitational wave data, in this paper we lay out the optimal techniques ... More
Precise Measurement of Laser Power using an Optomechanical SystemSep 18 2013Jan 26 2014This paper shows a novel method to precisely measure the laser power using an optomechanical system. By measuring a mirror displacement caused by the reflection of an amplitude modulated laser beam, the number of photons in the incident continuous-wave ... More
Cosmic Explorer: The U.S. Contribution to Gravitational-Wave Astronomy beyond LIGOJul 10 2019This white paper describes the research and development needed over the next decade to realize "Cosmic Explorer," the U.S. node of a future third-generation detector network that will be capable of observing and characterizing compact gravitational-wave ... More
On choosing the start time of binary black hole ringdownNov 02 2017Nov 06 2017The final stage of a binary black hole merger is ringdown, in which the system is described by a Kerr black hole with quasinormal mode perturbations. It is far from straightforward to identify the time at which the ringdown begins. Yet determining this ... More
The midpoint between dipole and parton showersJun 16 2015Sep 19 2015We present a new parton-shower algorithm. Borrowing from the basic ideas of dipole cascades, the evolution variable is judiciously chosen as the transverse momentum in the soft limit. This leads to a very simple analytic structure of the evolution. A ... More
Interactive Natural Language Acquisition in a Multi-modal Recurrent Neural ArchitectureMar 24 2017Feb 07 2018For the complex human brain that enables us to communicate in natural language, we gathered good understandings of principles underlying language acquisition and processing, knowledge about socio-cultural conditions, and insights about activity patterns ... More
The H-Covariant Strong Picard GroupoidSep 08 2004Apr 25 2005The notion of H-covariant strong Morita equivalence is introduced for *-algebras over C = R(i) with an ordered ring R which are equipped with a *-action of a Hopf *-algebra H. This defines a corresponding H-covariant strong Picard groupoid which encodes ... More
A shortcut to (sun)flowers: Kernels in logarithmic space or linear timeApr 30 2015We investigate whether kernelization results can be obtained if we restrict kernelization algorithms to run in logarithmic space. This restriction for kernelization is motivated by the question of what results are attainable for preprocessing via simple ... More
Weak Limit of the 3-State Quantum Walk on the LineApr 04 2014May 21 2014We revisit the one dimensional discrete time quantum walk with 3 states and the Grover coin. We derive analytic expressions for observed the localization, an long time approximation for the probability density function (PDF). We also connect the time ... More
Streaming KernelizationMay 06 2014Kernelization is a formalization of preprocessing for combinatorially hard problems. We modify the standard definition for kernelization, which allows any polynomial-time algorithm for the preprocessing, by requiring instead that the preprocessing runs ... More
On the commutability of homogenization and linearization in finite elasticityNov 16 2010May 16 2011We study non-convex elastic energy functionals associated to (spatially) periodic, frame indifferent energy densities with a single non-degenerate energy well at SO(n). Under the assumption that the energy density admits a quadratic Taylor expansion at ... More
Finite-Size Corrections for Ground States of Edwards-Anderson Spin GlassesOct 28 2011May 30 2012Extensive computations of ground state energies of the Edwards-Anderson spin glass on bond-diluted, hypercubic lattices are conducted in dimensions d=3,..,7. Results are presented for bond-densities exactly at the percolation threshold, p=p_c, and deep ... More
Superstability of the yeast cell cycle dynamics: Ensuring causality in the presence of biochemical stochasticityMay 05 2006Gene regulatory dynamics is governed by molecular processes and therefore exhibits an inherent stochasticity. However, for the survival of an organism it is a strict necessity that this intrinsic noise does not prevent robust functioning of the system. ... More
The generating of Fractal Images Using MathCAD ProgramMar 24 2009This paper presents the graphic representation in the z-plane of the first three iterations of the algorithm that generates the Sierpinski Gasket. It analyzes the influence of the f(z) map when we represent fractal images.
Projection methods for ill-posed problems revisitedJul 13 2015The discretization of least-squares problems for linear ill-posed operator equations in Hilbert spaces is considered. The main subject of this article concerns conditions for convergence of the associated discretized minimum-norm least-squares solution ... More
Twisted Reidemeister torsion, the Thurston norm and fibered manifoldsJan 29 2013We prove that the twisted Reidemeister torsion of a 3-manifold corresponding to a fibered class is monic and we show that it gives lower bounds on the Thurston norm. The former fixes a flawed proof in [FV10], the latter gives a quick alternative argument ... More
Reidemeister torsion, the Thurston norm and Harvey's invariantsAug 31 2005Feb 25 2006Recently twisted and higher order Alexander polynomials were used by Cochran, Harvey, Friedl--Kim and Turaev to give lower bounds on the Thurston norm. We first show how Reidemeister torsion relates to these Alexander polynomials. We then give lower bounds ... More
A Hidden Signal in the Ulam sequenceJul 01 2015Jul 06 2016The Ulam sequence is defined as $a_1 =1, a_2 = 2$ and $a_n$ being the smallest integer that can be written as the sum of two distinct earlier elements in a unique way. This gives $$1, 2, 3, 4, 6, 8, 11, 13, 16, 18, 26, 28, 36, 38, 47, \dots$$ Ulam remarked ... More
New Bounds for the Traveling Salesman ConstantNov 25 2013Mar 27 2014Let $X_1, X_2, \dots, X_n$ be independent and uniformly distributed random variables in the unit square $[0,1]^2$ and let $L(X_1, \dots, X_n)$ be the length of the shortest traveling salesman path through these points. In 1959, Beardwood, Halton $\&$ ... More
Nonextensive statistical mechanics and complex scale-free networksSep 07 2006One explanation for the impressive recent boom in network theory might be that it provides a promising tool for an understanding of complex systems. Network theory is mainly focusing on discrete large-scale topological structures rather than on microscopic ... More
Aging Exponents in Self-Organized CriticalityJun 11 1997Aug 07 1997In a recent Letter [Phys. Rev. Lett. 79, 889 (1997) and cond-mat/9702054] we have demonstrated that the avalanches in the Bak-Sneppen model display aging behavior similar to glassy systems. Numerical results for temporal correlations show a broad distribution ... More
Stiffness of the Edwards-Anderson Model in all DimensionsAug 01 2005Sep 23 2005A comprehensive description in all dimensions is provided for the scaling exponent $y$ of low-energy excitations in the Ising spin glass introduced by Edwards and Anderson. A combination of extensive numerical as well as theoretical results suggest that ... More
Neutron skin thickness of heavy nuclei with $α$-particle correlations and the slope of the nuclear symmetry energyMar 12 2014Jun 16 2014The formation of $\alpha$-particle clusters on the surface of heavy nuclei is described in a generalized relativistic mean-field model with explicit cluster degrees of freedom. The effects on the size of the neutron skin of Sn nuclei and ${}^{208}$Pb ... More
Fermions and the scattering equationsDec 18 2014Mar 03 2015This paper investigates how tree-level amplitudes with massless quarks, gluons and/or massless scalars transforming under a single copy of the gauge group can be expressed in the context of the scattering equations as a sum over the inequivalent solutions ... More
The SISCone jet algorithm optimised for low particle multiplicitiesAug 09 2011Dec 10 2011The SISCone jet algorithm is a seedless infrared-safe cone jet algorithm. There exists an implementation which is highly optimised for a large number of final state particles. However, in fixed-order perturbative calculations with a small number of final ... More
Does one need the O(epsilon)- and O(epsilon^2)-terms of one-loop amplitudes in an NNLO calculation ?Jul 26 2011Sep 12 2011This article discusses the occurences of one-loop amplitudes within a next-to-next-to-leading order calculation. In an NNLO calculation the one-loop amplitude enters squared and one would therefore naively expect that the O(epsilon)- and O(epsilon^2)-terms ... More
Automated calculations for multi-leg processesJul 23 2007Jul 26 2007The search for signals of new physics at the forthcoming LHC experiments involves the analysis of final states characterised by a high number of hadronic jets or identified particles. Precise theoretical predictions for these processes require the computation ... More
Hopf algebra structures in particle physicsOct 14 2003In the recent years, Hopf algebras have been introduced to describe certain combinatorial properties of quantum field theories. I will give a basic introduction to these algebras and review some occurrences in particle physics.
Moments of event shapes in electron-positron annihilation at NNLOSep 28 2009Nov 10 2009This article gives the perturbative NNLO results for the moments of the most commonly used event shape variables associated to three-jet events in electron-positron annihilation: Thrust, heavy jet mass, wide jet broadening, total jet broadening, C parameter ... More
Introduction to Monte Carlo methodsJun 23 2000These lectures given to graduate students in high energy physics, provide an introduction to Monte Carlo methods. After an overview of classical numerical quadrature rules, Monte Carlo integration together with variance-reducing techniques is introduced. ... More
Calculational techniques (not only) for single top productionMay 29 2000A next-to-leading order calculation for single top production including spin-dependent observables requires efficient techniques for the calculation of the relevant loop amplitudes. We discuss the adaption of dimensional regularization, the spinor helicity ... More
Coherent states and geodesics: cut locus and conjugate locusFeb 22 1995Sep 15 1995The intimate relationship between coherent states and geodesics is pointed out. For homogenous manifolds on which the exponential from the Lie algebra to the Lie group equals the geodesic exponential, and in particular for symmetric spaces, it is proved ... More
Symmetry Dependence of Localization in Quasi- 1- dimensional Disordered WiresMar 26 2000Jun 25 2000The crossover in energy level statistics of a quasi-1-dimensional disordered wire as a function of its length L is used, in order to derive its averaged localization length, without magnetic field, in a magnetic field and for moderate spin orbit scattering ... More
Indirect Detection of Dark Matter with gamma raysOct 10 2013Feb 12 2014The details of what constitutes the majority of the mass that makes up dark matter in the Universe remains one of the prime puzzles of cosmology and particle physics today - eighty years after the first observational indications. Today, it is widely accepted ... More
Status of the NLO Corrections to the Photon Impact FactorJun 20 2002We present the status of the programme of calculating the next-to-leading order corrections to the virtual photon impact factor. In particular, we discuss new results for the transversely polarized photon. We briefly outline the definition of infrared ... More
Herwig++ for e+e- collisionsAug 03 2004Some results obtained with the new Monte Carlo event generator Herwig++ are presented. In its first version (1.0), Herwig++ is capable of simulating e+e- Annihilation events. We discuss its relevance for future e+e- colliders and show results on the multiplicity ... More
From Unified Theories to Precision Neutrino ExperimentsAug 31 2006The expected high sensitivities of future neutrino oscillation experiments will allow precision tests of unified theories of flavour. In order to compare GUT scale predictions for neutrino masses, leptonic mixing angles and CP violating phases with experimental ... More
On Polynomial Kernels for Integer Linear Programs: Covering, Packing and FeasibilityFeb 14 2013Feb 15 2013We study the existence of polynomial kernels for the problem of deciding feasibility of integer linear programs (ILPs), and for finding good solutions for covering and packing ILPs. Our main results are as follows: First, we show that the ILP Feasibility ... More
On Polynomial Kernels for Sparse Integer Linear ProgramsFeb 14 2013Feb 15 2013Integer linear programs (ILPs) are a widely applied framework for dealing with combinatorial problems that arise in practice. It is known, e.g., by the success of CPLEX, that preprocessing and simplification can greatly speed up the process of optimizing ... More
Polynomial Kernelizations for MIN F^+Pi_1 and MAX NPFeb 11 2009Dec 13 2011It has been observed in many places that constant-factor approximable problems often admit polynomial or even linear problem kernels for their decision versions, e.g., Vertex Cover, Feedback Vertex Set, and Triangle Packing. While there exist examples ... More
The asymptotic rank of metric spacesJan 08 2007Oct 20 2008In this article we define and study a notion of asymptotic rank for metric spaces and show in our main theorem that for a large class of spaces, the asymptotic rank is characterized by the growth of the higher filling functions. For a proper, cocompact, ... More
Nilpotent groups without exactly polynomial Dehn functionApr 16 2010We prove super-quadratic lower bounds for the growth of the filling area function of a certain class of Carnot groups. This class contains groups for which it is known that their Dehn function grows no faster than $n^2\log n$. We therefore obtain the ... More
Theta divisors with curve summands and the Schottky problemSep 10 2014Aug 25 2015We prove the following converse of Riemann's Theorem: let (A,\Theta) be an indecomposable principally polarized abelian variety whose theta divisor can be written as a sum of a curve and a codimension two subvariety \Theta=C+Y. Then C is smooth, A is ... More
A Remark on Non-equivalent Star Products via Reduction for CP^nFeb 17 1998In this paper we construct non-equivalent star products on CP^n by phase space reduction. It turns out that the non-equivalent star products occur very natural in the context of phase space reduction by deforming the momentum map of the U(1)-action on ... More
The Covariant Picard Groupoid in Differential GeometrySep 23 2005In this article we discuss some general results on the covariant Picard groupoid in the context of differential geometry and interpret the problem of lifting Lie algebra actions to line bundles in the Picard groupoid approach.
Flavor physics with $Λ_b$ baryonsJan 13 2014Feb 26 2015At the LHC, bottom baryons are being produced in unprecedented quantities, which opens up a new field for flavor physics. For example, the decay $\Lambda_b \to p \mu^- \bar{\nu}$ can be used to obtain a novel determination of the CKM matrix element $|V_{ub}|$, ... More
A causal perspective on random geometryMay 02 2009In this thesis we investigate the importance of causality in non-perturbative approaches to quantum gravity. Firstly, causal sets are introduced as a simple kinematical model for causal geometry. It is shown how causal sets could account for the microscopic ... More
Hyperon-nucleon interaction and baryonic contact terms in SU(3) chiral effective field theoryDec 16 2013In this proceeding we summarize results for baryonic contact terms derived within SU(3) chiral effective field theory. The four-baryon contact terms, necessary for the description of the hyperon-nucleon interaction, include SU(3) symmetric and explicit ... More
Density of states near the Mott-Hubbard transition in the limit of large dimensionsMar 12 1998Oct 30 1998The zero temperature Mott-Hubbard transition as a function of the Coulomb repulsion U is investigated in the limit of large dimensions. The behavior of the density of states near the transition at U=U_c is analyzed in all orders of the skeleton expansion. ... More
A model of semimetallic behavior in strongly correlated electron systemsNov 17 1998Metals with values of the resistivity and the Hall coefficient much larger than typical ones, e.g., of sodium, are called semimetals. We suggest a model for semimetals which takes into account the strong Coulomb repulsion of the charge carriers, especially ... More
Data Unfolding Methods in High Energy PhysicsNov 07 2016A selection of unfolding methods commonly used in High Energy Physics is compared. The methods discussed here are: bin-by-bin correction factors, matrix inversion, template fit, Tikhonov regularisation and two examples of iterative methods. Two procedures ... More
The semiclassical small-$\hbar$ limit of loci of roots of fundamental solutions for polynomial potentialsMay 04 2008Dec 15 2008In this paper a description of the small-$\hbar$ limit of loci of zeros of fundamental solutions for polynomial potentials is given. The considered cases of the potentials are bounded to the ones which provided us with simple turning points only. Among ... More
New opportunities with spectro-interferometry and spectro-astrometryDec 15 2013Latest-generation spectro-interferometric instruments combine a milliarcsecond angular resolution with spectral capabilities, resulting in an immensely increased information content. Here, I present methodological work and results that illustrate the ... More
A Common View on Strong, Uniform, and Other Notions of Equivalence in Answer-Set ProgrammingDec 06 2007Logic programming under the answer-set semantics nowadays deals with numerous different notions of program equivalence. This is due to the fact that equivalence for substitution (known as strong equivalence) and ordinary equivalence are different concepts. ... More
A generalized likelihood ratio test statistic for Cherenkov telescope dataDec 04 2011Jun 15 2012Astrophysical sources of TeV gamma rays are usually established by Cherenkov telescope observations. These counting type instruments have a field of view of few degrees in diameter and record large numbers of particle air showers via their Cherenkov radiation ... More
An amusing sequence of functionsOct 11 2016We consider the amusing sequence of functions $f_n: \mathbb{R} \rightarrow \mathbb{R}$ given by $$ f_n(x) = \sum_{k=1}^{n}{\frac{|\sin{(k \pi x)}|}{k}}.$$ Every rational point is eventually the location of a strict local minimum of $f_n$: more precisely, ... More
Generation of real algebraic loci via complex detoursOct 19 2015May 03 2016We discuss the locus generation algorithm used by the dynamic geometry software Cinderella, and how it uses complex detours to resolve singularities. We show that the algorithm is independent of the orientation of its complex detours. We conjecture that ... More
On the arithmetic rank of projective subspace arrangementsJul 08 2016If $V$ is a projective subspace arrangement over an infinite field, consisting of $m$ irreducible components all intersecting in the empty set, and each of codimension $c_i,i=1,\ldots,m$, then the arithmetic rank of the defining ideal of $V$ is bounded ... More
Power correction analyses in e+e- annihilationSep 29 2000The current status of theoretical work and experimental analyses on power corrections in QCD for e+e- annihilation will be reviewed. Measurements of the number of active quark flavours n_f and the QCD colour factors C_A and C_F derived from QCD fits to ... More
Deformations of WZW modelsDec 17 2003Jan 12 2004Current-current deformations for WZW models of semisimple compact groups are discussed in a sigma model approach. We start with the abelian rank one group U(1). Afterwards, we keep the rank one but allow for non abelian structures by considering SU(2). ... More
Gauging Flavour in Meta-Stable Susy Breaking ModelsAug 04 2006Aug 16 2006We modify the first ISS model (hep-th/0602239) by gauging a diagonal flavour symmetry. We add additional multiplets transforming as fundamentals and anti-fundamentals under the gauged flavour group. Their number is chosen such that the microscopic theory ... More
Strings, Branes and Extra DimensionsOct 05 2001Jan 03 2002This review is devoted to strings and branes. Firstly, perturbative string theory is introduced. The appearance of various types of branes is discussed. These include orbifold fixed planes, D-branes and orientifold planes. The connection to BPS vacua ... More
Implementation and Evaluation of multimodal input/output channels for task-based industrial robot programmingMar 17 2015Programming industrial robots is not very intuitive, and the programmer has to be a domain expert for e.g. welding and programming to know how the task is optimally executed. For SMEs such employees are not affordable, nor cost-effective. Therefore a ... More
Lectures on configuration space methods for sunrise-type diagramsJul 23 2003In this lecture series I will give a fundamental insight into configuration space techniques which are of help to calculate a broad class of Feynman diagrams, the sunrise-type diagrams. Applications are shown along with basic concepts and techniques.
Analyzing QCD Sum Rules for Heavy Baryons at Next-to-Leading Order in α_SOct 15 1997In this talk I consider QCD sum rules for the ground state heavy baryons to leading order in $1/m_Q$ and at next-to-leading order in $\alpha_S$ within the context of Heavy Quark Symmetry. The analysis is done at a fixed scale $\mu=1 GeV$. The evolution ... More
On the Stokes matrices of the $tt^*$-Toda equationOct 01 2016We derive a formula for the signature of the symmetrized Stokes matrix $\cal{S}+\cal{S}^\mathrm{T}$ for the $tt^*$-Toda equation. As a corollary, we verify a conjecture of Cecotti and Vafa regarding when $\cal{S}+\cal{S}^\mathrm{T}$ is positive definite, ... More
Gaia - A White Dwarf Discovery MachineOct 30 2006The Gaia data will help to improve the construction of a luminosity function for the disk and the halo and will provide a more accurate determination of the age of our solar neighborhood. Moreover, reliable stellar dynamical investigations of the disk ... More
Gauge covariant heat kernel expansion at finite temperatureFeb 18 2003The heat kernel method is extended to the case of finite temperature. Special emphasis is given to the study of gauge theories. Due to the compactness of space in the Euclidean time direction (inverse temperature) the field strength cannot completely ... More
Resummation of soft modes in the free energy of Phi^4 theoryAug 26 1998Nov 24 1998A new method is proposed for the calculation of the free energy of an N-component Phi^4 theory at finite temperature. The method combines a perturbative treatment of the hard modes with a non-perturbative treatment in the effectively three-dimensional ... More
A model and sensitivity analysis of the quality economics of defect-detection techniquesDec 12 2016One of the main cost factors in software development is the detection and removal of defects. However, the relationships and influencing factors of the costs and revenues of defect-detection techniques are still not well understood. This paper proposes ... More
The Use of Application Scanners in Software Product Quality AssessmentNov 21 2016Software development needs continuous quality control for a timely detection and removal of quality problems. This includes frequent quality assessments, which need to be automated as far as possible to be feasible. One way of automation in assessing ... More
A Compactness Principle for Maximizing Smooth Functions over Toroidal GeodesicsMay 07 2018Nov 15 2018Let $f \in C^2(\mathbb{T}^2)$ have mean value 0 and consider $$ \sup_{\gamma~{\tiny \mbox{closed geodesic}}}{~~~ \frac{1}{|\gamma|} \left| \int_{\gamma}{ f ~~d\mathcal{H}^1}\right| },$$ where $\gamma$ ranges over all closed geodesics $\gamma:\mathbb{S}^1 ... More
Link concordance, boundary link concordance and eta invariantsJun 09 2003We study the eta-invariants of links and show that in many cases they form link concordance invariants, in particular that many eta-invariants vanish for slice links. This result contains and generalizes previous invariants by Smolinsky and Cha--Ko. We ... More
A remark on the Chisini conjectureJan 20 2000The Chisini conjecture asserts that a generic ramified covering over the complex projective plane of degree at least 5 is uniquely determined by its branch curve. We prove this for degree at least 12 using the work of Kulikov (math-AG/9803144).
Enriques surfaces with normal K3-like coveringsMar 09 2017We study simply-connected Enriques surface in characteristic two whose K3-like covering is normal, building on the work of Ekedahl, Hyland and Shepherd-Barron. We develop general methods to construct examples in a systematic fashion, including the case ... More
The Quantum Query Complexity of Elliptic PDEDec 27 2005The complexity of the following numerical problem is studied in the quantum model of computation: Consider a general elliptic partial differential equation of order 2m in a smooth, bounded domain Q\subset \R^d with smooth coefficients and homogeneous ... More
Non-equilibrium almost-stationary states and linear response for gapped quantum systemsAug 11 2017Sep 30 2018We prove the validity of linear response theory at zero temperature for perturbations of gapped Hamiltonians describing interacting fermions on a lattice. As an essential innovation, our result requires the spectral gap assumption only for the unperturbed ... More
Recent Progress in Effective Field Theory in the One-Nucleon SectorOct 12 2007Chiral perturbation theory (ChPT) is the effective field theory of the strong interactions at low energies. We will address the issue of a consistent power counting scheme in a manifestly Lorentz-invariant formulation of baryon ChPT. As applications we ... More
The real Jacobi group revisitedMar 26 2019The real Jacobi group $G^J_1(\mathbb{R})$, defined as the semidirect product of the group $\rm{SL}(2,\mathbb{R})$ with the Heisenberg group $H_1$, is embedded in the $4\times 4$ matrix realisation of the group $\text{Sp}(2,\mathbb{R})$. The left-invariant ... More
A sharp Lp Lq Fourier restriction theorem for a conical surface of finite typeAug 29 2012Aug 04 2015We present a restriction theorem for the Fourier transform to a 2-dimensional conical surface of finite type, obtaining a sharp result, which improves previous work by Barcelo.
Diffusion of a Test Chain in a Quenched Background of Semidilute PolymersMar 03 1999Based on a recently established formalism (U. Ebert, J. Stat. Phys. 82, 183 (1996)) we analyze the diffusive motion of a long polymer in a quenched random medium. The medium is modeled by a frozen semidilute polymer system. In the framework of standard ... More
Full signature invariants for $L_0(F(t))$May 28 2003We find full invariants for detecting non--zero elements in ${L}_0(F(t))\otimes \Q$, this group plays an important role in topology in the work done by Casson and Gordon.
A Metric Sturm-Liouville theory in Two DimensionsSep 04 2018A central result of Sturm-Liouville theory (also called the Sturm-Hurwitz Theorem) states that if $\phi_k$ is a sequence of eigenfunctions of a second order differential operator on the interval $I \subset \mathbb{R}$, then any linear combination satisfies ... More
Lasso and equivalent quadratic penalized modelsJan 10 2014The least absolute shrinkage and selection operator (lasso) and ridge regression produce usually different estimates although input, loss function and parameterization of the penalty are identical. In this paper we look for ridge and lasso models with ... More
Changing the topology of Tensor NetworksMar 07 2012In many applications, it is needed to change the topology of a tensor network directly and without approximation. This work will introduce a general scheme that satisfies these needs. We will describe the procedure by two examples and show its efficiency ... More
Algorithms for lattice QCD: progress and challengesNov 25 2010The development of improved algorithms for QCD on the lattice has enabled us to do calculations at small quark masses and get control over the chiral extrapolation. Also finer lattices have become possible, however, a severe slowing down associated with ... More
Algorithms for dynamical overlap fermionsSep 28 2006An overview of the current status of algorithmic approaches to dynamical overlap fermions is given. In particular the issue of changing the topological sector is discussed.
Dynamics near manifolds of equilibria of codimension one and bifurcation without parametersApr 20 2010Sep 07 2010We investigate the breakdown of normal hyperbolicity of a manifold of equilibria of a flow. In contrast to classical bifurcation theory we assume the absence of any flow-invariant foliation at the singularity transverse to the manifold of equilibria. ... More
ICARUS and Status of Liquid Argon TechnologyOct 07 2011ICARUS is the largest liquid argon TPC detector ever built (~600 ton LAr mass). It operates underground at the LNGS laboratory in Gran Sasso. It has been smoothly running since summer 2010, collecting data with the CNGS beam and with cosmics. Liquid argon ... More
Some results on the lattice parameters of quaternionic Gabor framesJul 17 2015Gabor frames play a vital role not only modern harmonic analysis but also in several fields of applied mathematics, for instances, detection of chirps, or image processing. In this work we present a non-trivial generalization of Gabor frames to the quaternionic ... More
Point Lattices and Oscillating Recurrence SequencesFeb 14 2005Feb 21 2005We consider the following question: Which real sequences (a(n)) that satisfy a linear recurrence with constant coefficients are positive for sufficiently large n? We show that the answer is negative for both (a(n)) and (-a(n)), if the dominating characteristic ... More