Results for "Horst Borrmann"

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Observation and manipulation of maximal Chern numbers in the chiral topological semimetal PdGaJul 19 2019Topological semimetals feature protected nodal band degeneracies characterized by a topological invariant known as the Chern number. The magnitude and sign of this invariant determine many of the exotic properties of such semimetals, including the number ... More
The interplay between shell effects and electron correlations in quantum dotsFeb 17 2000Jun 08 2000We use the Path Integral Monte Carlo method to investigate the interplay between shell effects and electron correlations in single quantum dots with up to 12 electrons. By use of an energy estimator based on the hypervirial theorem of Hirschfelder we ... More
The Origins of Phase Transitions in Small SystemsApr 17 2001The identification and classification of phases in small systems, e.g. nuclei, social and financial networks, clusters, and biological systems, where the traditional definitions of phase transitions are not applicable, is important to obtain a deeper ... More
Synthesis and Crystal Growth of Tetragonal Fe1.00SeAug 21 2015Aug 24 2015Single crystals of tetragonal Fe1.00Se were grown from polycrystalline material by chemical vapor transport reaction at temperatures below 723 K using AlCl3 as transport additive. The plate-shaped single crystals have edge lengths up to 4 mm. The single ... More
Chiral Quasiparticles at the Fermi Surface of the Weyl Semimetal TaAsMar 29 2016Tantalum arsenide is a member of the non-centrosymmetric monopnictides, which are putative Weyl semimetals. In these materials, three-dimensional chiral massless quasiparticles, the so-called Weyl fermions, are predicted to induce novel quantum mechanical ... More
An ergodic diffusion with unbounded inward and outward driftMay 22 2012It is argued that a diffusion may be ergodic even though the drift field has unbounded outward-directed parts. The discussion employs stochastic and numerical methods.
Quantized Photocurrents in the Chiral Multifold Fermion System RhSiFeb 08 2019The rapid pace of discovery of new classes of Weyl semimetals is driving a search for properties that derive from their unique bandstructure topology. One of the most striking of the predicted properties is the quantized circular photogalvanic effect ... More
Summary of theoretical contributionsJun 04 2005Results from various theoretical approaches and ideas presented at this exciting meeting are reviewed. I also point towards future directions, in particular hydrodynamic behaviour induced by jets traveling through the quark-gluon plasma, which might be ... More
Effective field theory for lambda-sigma^0 mixing in nuclear matterOct 16 1998We extend the effective field theory approach which successfully describes ordinary nuclei and nuclear matter to incorporate strangeness in nuclear structure. Central object is a chiral effective Lagrangian involving the baryon octet, the Goldstone boson ... More
Susceptibility Crossover Behavior in He3 and Xe Near Their Liquid-Vapor Critical Point - A Progress ReportMay 16 2001Sep 19 2002A discussion is presented on the crossover of the susceptibility from mean-field to Ising critical behavior upon approaching the critical point from below and from above Tc, both for He3 and Xe. Fits of the experimental susceptibility data are made to ... More
Paradoxical Magnetic Cooling in a Structural Transition ModelSep 04 2000Feb 02 2001In contrast to the experimentally widely used isentropic demagnetization process for cooling to ultra-low temperatures we examine a particular classical model system that does not cool, but rather heats up with isentropic demagnetization. This system ... More
Calculation of thermodynamic properties of finite Bose-Einstein systemsAug 04 2000We derive an exact recursion formula for the calculation of thermodynamic functions of finite systems obeying Bose-Einstein statistics. The formula is applicable for canonical systems where the particles can be treated as noninteracting in some approximation, ... More
Mini Black Holes in the first year of the LHCJul 14 2006Jul 24 2006The experimental signatures of TeV-mass black hole (BH) formation in heavy ion collisions at the LHC is examined. We find that the black hole production results in a complete disappearance of all very high $p_T$ ({$> 500$} GeV) back-to-back correlated ... More
Collective Flow signals the Quark Gluon PlasmaJun 07 2004A critical discussion of the present status of the CERN experiments on charm dynamics and hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A$\cdot$GeV: here the hydrodynamic model has predicted ... More
Stable TeV - Black Hole Remnants at the LHC: Discovery through Di-Jet Suppression, Mono-Jet Emission and a Supersonic Boom in the Quark-Gluon PlasmaMay 05 2006Jun 20 2006The production of Large Extra Dimension (LXD) Black Holes (BHs), with a new, fundamental mass scale of $M_f = 1$ TeV, has been predicted to occur at the Large Hadron Collider, LHC, with the formidable rate of $10^8$ per year in p-p collisions at full ... More
The Deconfinement Phase Transition in Asymmetric MatterJan 19 1997We study the phase transition of asymmetric hadronic matter to a quark-gluon plasma within the framework of a simple two-phase model. The analysis is performed in a system with two conserved charges (baryon number and isospin) using the stability conditions ... More
Collapse of Flow: Probing the Order of the Phase TransitionOct 26 2007We discuss the present collective flow signals for the phase transition to the quark-gluon plasma (QGP) and the collective flow as a barometer for the equation of state (EoS). We emphasize the importance of the flow excitation function from 1 to $50 A$ ... More
Long-time behaviour of a fully discrete Lagrangian scheme for a family of fourth orderJan 20 2015Jan 22 2015A fully discrete Lagrangian scheme for solving a family of fourth order equations numerically is presented. The discretization is based on the equation's underlying gradient flow structure w.r.t. the $L^2$-Wasserstein distance, and adapts numerous of ... More
Quantum Oscillations and Magnetic Reconstruction in the Delafossite PdCrO$_2$Apr 30 2015We report quantum oscillation data on the metallic triangular antiferromagnet PdCrO$_2$. We find that, to very high accuracy, the observed frequencies of PdCrO$_2$ can be reproduced by reconstruction of the (nonmagnetic) PdCoO$_2$ Fermi surface into a ... More
Ternary borides Nb$_7$Fe$_3$B$_8$ and Ta$_7$Fe$_3$B$_8$ with Kagome-type iron frameworkJun 09 2016Two new ternary borides $TM$$_7$Fe$_3$B$_8$ ($TM$ = Nb, Ta) were synthesized by high-temperature thermal treatment of samples obtained by arc-melting. This new type of structure with space group $P$6/$mmm$, comprises $TM$ slabs containing isolated planar ... More
Giant anomalous Hall angle in a half-metallic magnetic Weyl semimetalDec 19 2017Dec 31 2017Magnetic Weyl semimetals (WSMs) with time reversal symmetry breaking exhibit Weyl nodes that act as monopoles of Berry curvature and are thus expected to generate a large intrinsic anomalous Hall effect (AHE). However, in most magnetic WSMs, the Weyl ... More
Observation of an anomalous heat current in a Weyl fermion semimetalOct 04 2018The curvature of space-time and its consequences are often far removed from experimental accessibility. A particularly elusive effect is the generation of a heat current by the mixed axial-gravitational anomaly. However, recent theoretical investigations ... More
Pressure-driven Superconductivity in Transition-metal Pentatelluride HfTe5Feb 27 2016Layered transition-metal tellurides have attracted considerable attention because of their rich physics; for example, tungsten ditelluride WTe2 exhibits extremely large magnetoresistance; the tritelluride ZrTe3 shows a charge density wave transition at ... More
Estimating Maximum Error Impact in Dynamic Data-driven Applications for Resource-aware Adaption of Software-based Fault-ToleranceAug 22 2016The rise of transient faults in modern hardware requires system designers to consider errors occurring at runtime. Both hardware- and software-based error handling must be deployed to meet application reliability requirements. The level of required reliability ... More
How sensitive are the thermal fits to heavy-ion hadron yield data to the modeling of the eigenvolume interactions?Jun 20 2016The hadron-resonance gas (HRG) model with eigenvolume corrections is employed to fit the hadron yield data of the NA49 collaboration for central Pb+Pb collisions at $\sqrt{s_{NN}}$ = 6.3, 7.6, 8.8, 12.3, and 17.3 GeV, the hadron midrapidity yield data ... More
Strangeness-changing response functions:an alternative approach to hypernuclear structureOct 29 1999We study strangeness-changing response functions as an alternative description of hypernuclear structure. Hypernuclear states are treated in the same manner as any other conventional nuclear excitation that emerges from the response of the nuclear ground ... More
Critical analysis of a variational method used to describe the molecular electron transportAug 01 2011In a recent paper [I.\ B\^aldea and H.\ K\"oppel, \prb {\bf 78}, 115315 (2008)], we showed that a variational approach [P.\ Delaney and J.\ C.\ Greer, \prl {\bf 93}, 036805 (2004)] proposed to compute the electron transport through molecules, which is ... More
A physical limitation of the Wigner "distribution" function in transportFeb 28 2011We present an example revealing that the sign of the "momentum" $P$ of the Wigner "distribution" function $f(q, P)$ is not necessarily associated with the direction of motion in the real world. This aspect, which is not related to the well known limitation ... More
Rational matrix solutions to the Leech equation: The Ball-Trent approach revisitedJan 22 2013Using spectral factorization techniques, a method is given by which rational matrix solutions to the Leech equation with rational matrix data can be computed explicitly. This method is based on an approach by J.A. Ball and T.T. Trent, and generalizes ... More
On the Geometry of the IBEX RibbonAug 31 2015The Energetic Neutral Atom (ENA) full-sky maps obtained with the Interstellar Boundary Explorer (IBEX) show an unexpected bright narrow band of increased intensity. This so-called ENA ribbon results from charge exchange of interstellar neutral atoms with ... More
Nonuniqueness of Representations of Wave Equations in Lorentzian Space-TimesNov 19 2012This brief note wants to bring to attention that the formulation of physically reasonable initial-boundary value problems for wave equations in Lorentzian space-times is not unique, i.e., that there are inequivalent such formulations that lead to a different ... More
Continuous viscosity solutions to linear-quadratic stochastic control problems with singular terminal state constraintSep 06 2018Jun 27 2019This paper establishes the existence of a unique nonnegative continuous viscosity solution to the HJB equation associated with a Markovian linear-quadratic control problems with singular terminal state constraint and possibly unbounded cost coefficients. ... More
A triviality result in the AdS/CFT correspondence for Euclidean quantum fields with exponential interactionSep 30 2012Aug 27 2013We consider scalar quantum fields with exponential interaction on Euclidean hyperbolic space $\mathbb{H}^2$ in two dimensions. Using decoupling inequalities for Neumann boundary conditions on a tessellation of $\mathbb{H}^2$, we are able to show that ... More
A convergent Lagrangian discretization for a nonlinear fourth order equationOct 07 2014A fully discrete Lagrangian scheme for numerical solution of the nonlinear fourth order DLSS equation in one space dimension is analyzed. The discretization is based on the equation's gradient flow structure in the $L^2$-Wasserstein metric. We prove that ... More
Relaxed commutant lifting: existence of a unique solutionAug 18 2008In this paper we present necessary and sufficient conditions for the existence of a unique solution to the relaxed commutant lifting problem. The obtained conditions are more complicated than those for the classical commutant lifting setting, and earlier ... More
A pre-order on positive real operators and its invariance under linear fractional transformationsAug 03 2014A pre-order and equivalence relation on the class of positive real Hilbert space operators are introduced, in correspondence with similar relations for contraction operators defined by Yu.L. Shmul'yan in [7]. It is shown that the pre-order, and hence ... More
Eigenvectors and eigenfunctionals of homogeneous order-preserving mapsFeb 15 2013This paper considers homogeneous order preserving continuous maps on the normal cone of an ordered normed vector space. It is shown that certain operators of that kind which are not necessarily compact themselves but have a compact power have a positive ... More
Mean Field Games with Singular ControlsDec 16 2016Aug 03 2017This paper establishes the existence of relaxed solutions to mean field games (MFGs for short) with singular controls. We also prove approximations of solutions results for a particular class of MFGs with singular controls by solutions, respectively control ... More
Functional Limit Theorems for Marked Hawkes Point MeasuresAug 19 2019This paper establishes a functional law of large numbers and a functional central limit theorem for marked Hawkes point measures and their corresponding shot noise processes. We prove that the normalized random measure can be approximated in distribution ... More
Conditional Analysis and a Principal-Agent problemDec 15 2014Jun 14 2016We analyze conditional optimization problems arising in discrete time Principal-Agent problems of delegated portfolio optimization with linear contracts. Applying tools from Conditional Analysis we show that some results known in the literature for very ... More
Order-disorder transition in nanoscopic semiconductor quantum ringsAug 31 2000Apr 02 2001Using the path integral Monte Carlo technique we show that semiconductor quantum rings with up to six electrons exhibit a temperature, ring diameter, and particle number dependent transition between spin ordered and disordered Wigner crystals. Due to ... More
Optimal Trade Execution with Instantaneous Price Impact and Stochastic ResilienceNov 10 2016We study an optimal execution problem in illiquid markets with both instantaneous and persistent price impact and stochastic resilience when only absolutely continuous trading strategies are admissible. In our model the value function can be described ... More
CleGo: A package for automated computation of Clebsch-Gordan coefficients in Tensor Product Representations for Lie Algebras A - GNov 17 2010We present a program that allows for the computation of tensor products of irreducible representations of Lie algebras A-G based on the explicit construction of weight states. This straightforward approach (which is slower and more memory-consumptive ... More
Beyond partial differential equations: A course on linear and quasi-linear abstract hyperbolic evolution equationsOct 21 2005May 06 2007This course introduces the use of semigroup methods in the solution of linear and nonlinear (quasi-linear) hyperbolic partial differential equations, with particular application to wave equations and Hermitian hyperbolic systems. Throughout the course ... More
On the Completeness of the Quasinormal Modes of the Poeschl-Teller PotentialMar 10 1998The completeness of the quasinormal modes of the wave equation with Poeschl-Teller potential is investigated. A main result is that after a large enough time $t_0$, the solutions of this equation corresponding to $C^{\infty}$-data with compact support ... More
Multifragmentation, Clustering, and Coalescence in Nuclear CollisionsFeb 22 2005Nuclear collisions at intermediate, relativistic, and ultra-relativistic energies offer unique opportunities to study in detail manifold fragmentation and clustering phenomena in dense nuclear matter. At intermediate energies, the well known processes ... More
Continuous viscosity solutions to linear-quadratic stochastic control problems with singular terminal state constraintSep 06 2018This paper establishes the existence of a unique nonnegative continuous viscosity solution to the HJB equation associated with a Markovian linear-quadratic control problems with singular terminal state constraint and possibly unbounded cost coefficients. ... More
The role of scalar and vector interactions on the collective flows in high energy heavy-ion collisions at high baryon density regionsJun 08 2019A newly developed relativistic quantum molecular dynamics approach with scalar and vector interactions based on the relativistic mean-field theory (RQMD.RMF) is employed to study the sensitivities of the equation of state (EoS) on the beam energy dependence ... More
On the stability of the massive scalar field in Kerr space-timeMay 25 2011The current early stage in the investigation of the stability of the Kerr metric is characterized by the study of appropriate model problems. Particularly interesting is the problem of the stability of the solutions of the Klein-Gordon equation, describing ... More
The Rosenthal-Szasz inequality for normed planesMar 31 2018May 27 2018We aim to study the classical Rosenthal-Szasz inequality for a plane whose geometry is given by a norm. This inequality states that the bodies of constant width have the largest perimeter among all planar convex bodies of given diameter. In the case where ... More
Competition of residents and invaders in a variable environment: Response to enemies and dangerous noiseAug 21 2015The possible control of competitive invasion by infection of the invader and multiplicative noise is studied. The basic model is the Lotka-Volterra competition system with emergent carrying capacities. Several stationary solutions of the non-infected ... More
A weak law of large numbers for a limit order book model with fully state dependent order dynamicsFeb 15 2015May 20 2016This paper studies a limit order book (LOB) model, in which the order dynamics depend on both, the current best available prices and the current volume density functions. For the joint dynamics of the best bid price, the best ask price, and the standing ... More
Nuclear Dynamics at the Particle ThresholdOct 14 2014Recently, new low-energy modes of excitation called pygmy resonances have been observed. Their distinct feature is the close connection to nuclear skin oscillations. A successful description of the pygmy resonances could be achieved in a microscopic theoretical ... More
Nuclear pygmy modes and the dynamics of the nuclear skinNov 05 2012The information on pygmy resonances reveals new aspects on the isospin dynamics of the nucleus with important astrophysical consequences. In this connection, the precise knowledge of nuclear response functions plays a key role in the determination of ... More
Heavy-ion hot hadron matter freezes out at T=170-320 MeV?Dec 25 2015Feb 02 2016The conventional hadron-resonance gas (HRG) model with the Particle Data Group (PDG) hadron input and the hadron type dependent eigenvolume corrections is employed to fit the ALICE hadron mid-rapidity yield data on the most central Pb+Pb collisions. For ... More
Evidence for psi' Regeneration in Heavy Ion CollisionsJan 28 2005The production of the psi' meson in Pb+Pb collisions at CERN SPS is analyzed. It provides an evidence for charmonium regeneration via charm quark-antiquark coalescence at hadronization.
Reply to Comment on "Critical analysis of a variational method used to describe molecular electron transport"Aug 04 2011We show that the failure of the Delaney-Greer (DG) variational ansatz for transport demonstrated by us in Phys.\ Rev.\ B {\bf 80}, 165301 (2009) (I) is not related to an unsuitable constraint that prevents a broken time-reversal symmetry or to real orbitals, ... More
Transition voltage spectroscopy: a challenge for vacuum tunneling models at nanoscaleJul 18 2011Several studies on the transition voltage ($V_t$) are based on calculations of the tunneling current within the Simmons model. In this paper devoted to vacuum nano-junctions, we compare the Simmons results for $V_t$ with those obtained from the exact ... More
Far-infrared absorption in single-electron transistors: Theoretical results and experiment proposalMay 08 2009Dec 30 2009We present theoretical results on far-infrared (FIR) absorption of single-electron transistors. Based on them, we propose and explain how to conduct combined FIR--dc-transport experiments to determine the charging energy and other relevant parameters, ... More
Reply to Comment on "Electron transport through correlated molecules computed using the time-independent Wigner function: Two critical tests''Jun 24 2010In their Comment, Greer et al (i) put us in charge of a pretended wrong claim, which we never made in Phys.~Rev.~B {\bf 78}, 115315 (2008), where we criticized a method (DG)proposed by two of them, (ii) incorrectly claim that the DG method can reproduce ... More
Quantum-wave pattern recognition: From simulations towards implementationMar 14 2003Mar 27 2003A simulated Hopfield-type neural-net-like model, which is realizable using quantum holography, is proposed for quantum associative memory and pattern recognition.
Dielectron production in proton--proton collisions at $\sqrt{s} = 7$\,TeV with ALICEApr 02 2019The ALICE Collaboration measured dielectron production as a function of the invariant mass ($m_{\rm ee}$), the pair transverse momentum ($p_{\rm T,ee}$) and the pair distance of closest approach ($\rm DCA_{ee}$) in pp collisions at $\sqrt{s} = 7$\,TeV. ... More
A new result on the Klein-Gordon equation in the background of a rotating black holeFeb 26 2008This short paper should serve as basis for further analysis of a previously found new symmetry of the solutions of the wave equation in the gravitational field of a Kerr black hole. Its main new result is the proof of essential self-adjointness of the ... More
On the well posedness of the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein's field equationsJun 01 2004We give a well posed initial value formulation of the Baumgarte-Shapiro-Shibata-Nakamura form of Einstein's equations with gauge conditions given by a Bona-Masso like slicing condition for the lapse and a frozen shift. This is achieved by introducing ... More
Remarks on the relation between physics and faithNov 10 2006It is a quite common view among people, that are not aware of the developments in modern physics, that it is part of human nature to substitute religious faith in places where there is no knowledge. Therefore, an increase in knowledge would lead to a ... More
Crossover behavior in He3 and Xe near their liquid-vapor critical pointJun 29 2000We present a detailed discussion of the crossover from mean-field to Ising critical behavior upon approach of the critical point, both for He3 and Xe. By combining different sets of experimental data, we are able to cover an unusually large temperature ... More
Salem numbers from a class of star-like treesJan 22 2015We study the Coxeter polynomials associated with certain star-like trees. In particular, we exhibit large Salem factors of these polynomials and give convergence properties of their dominant roots.
A Scaling Limit for Limit Order Books Driven by Hawkes ProcessesSep 05 2017Aug 08 2018In this paper we derive a scaling limit for an infinite dimensional limit order book model driven by Hawkes random measures. The dynamics of the incoming order flow is allowed to depend on the current market price as well as on a volume indicator. With ... More
Complete sets need not be reduced in Minkowski spacesFeb 25 2015It is well known that in $n$-dimensional Euclidean space ($n\geq 2$) the classes of (diametrically) complete sets and of bodies of constant width coincide. Due to this, they both form a proper subfamily of the class of reduced bodies. For $n$-dimensional ... More
Convergence of a fully discrete variational scheme for a thin-film equationSep 04 2015This paper is concerned with a rigorous convergence analysis of a fully discrete Lagrangian scheme for the Hele-Shaw flow, which is the fourth order thin-film equation with linear mobility in one space dimension. The discretization is based on the equation's ... More
Algorithms for ball hulls and ball intersections in strictly convex normed planesNov 26 2014Extending results of Hershberger and Suri for the Euclidean plane, we show that ball hulls and ball intersections of sets of $n$ points in strictly convex normed planes can be constructed in $O(n \log n)$ time. In addition, we confirm that, like in the ... More
Multi-dimensional Optimal Trade Execution under Stochastic ResilienceApr 11 2018Sep 06 2018We study a multi-dimensional optimal execution problem in illiquid markets with both instantaneous and persistent price impact and stochastic resilience. In our model the value function can be described by a multi-dimensional backward stochastic Riccati ... More
A pre-order and an equivalence relation on Schur class functions and their invariance under linear fractional transformationsAug 03 2014Motivated by work of Yu.L. Shmul'yan a pre-order and an equivalence relation on the set of operator-valued Schur class functions are introduced and the behavior of Redheffer linear fractional transformations (LFTs) with respect to these relations is studied. ... More
A diffusion approximation for limit order book modelsAug 05 2016Aug 24 2017This paper derives a diffusion approximation for a sequence of discrete-time one-sided limit order book models with non-linear state dependent order arrival and cancellation dynamics. The discrete time sequences are specified in terms of an $\R_+$-valued ... More
A law of large numbers for limit order booksJan 05 2015We define a stochastic model of a two-sided limit order book in terms of its key quantities \textit{best bid [ask] price} and the \textit{standing buy [sell] volume density}. For a simple scaling of the discreteness parameters, that keeps the expected ... More
Pygmy resonances and nucleosynthesisOct 09 2014Nov 14 2014A microscopic theoretical approach based on a self-consistent density functional theory for the nuclear ground state and QRPA formalism extended with multi-phonon degrees of freedom for the nuclear excited states is implemented in investigations of new ... More
Thermodynamics of finite magnetic two-level systemsJan 29 1996We use Monte Carlo simulations to investigate the thermodynamical behaviour of aggregates consisting of few superparamagnetic particles in a colloidal suspension. The potential energy surface of this classical two-level system with a stable and a metastable ... More
Thermal Properties of Asymmetric Nuclear MatterJul 09 2014Mar 01 2015The thermal properties of asymmetric nuclear matter are investigated in a relativistic mean- field approach. We start from free space NN-interactions and derive in-medium self-energies by Dirac-Brueckner theory. By the DDRH procedure we derive in a self-consistent ... More
Analysis of hadron yield data within hadron resonance gas model with multi-component eigenvolume correctionsOct 07 2016We analyze the sensitivity of thermal fits to heavy-ion hadron yield data of ALICE and NA49 collaborations to the systematic uncertainties in the hadron resonance gas (HRG) model related to the modeling of the eigenvolume interactions. We find a surprisingly ... More
On a method to calculate conductance by means of the Wigner function: two critical testsJun 03 2008We have implemented the linear response approximation of a method proposed to compute the electron transport through correlated molecules based on the time-independent Wigner function [P. Delaney and J. C. Greer, \prl {\bf 93}, 36805 (2004)]. The results ... More
Results on the spectrum of R-Modes of slowly rotating relativistic starsMar 12 2002The paper considers the spectrum of axial perturbations of slowly uniformly rotating general relativistic stars in the framework of Y. Kojima. In a first step towards a full analysis only the evolution equations are treated but not the constraint. Then ... More
On the stability of the Kerr metricAug 16 2000The reduced (in the angular coordinate $\phi$) wave equation and Klein-Gordon equation are considered on a Kerr background and in the framework of $C^{0}$-semigroup theory. Each equation is shown to have a well-posed initial value problem,i.e., to have ... More
The Effects of Using Business Intelligence Systems on an Excellence Management and Decision-Making Process by Start-Up Companies: A Case StudyJan 18 2019The rapid increase in data volumes in companies has meant that momentous and comprehensive information gathering is barely possible by manual means. Business intelligence solutions can help here. They provide tools with appropriate technologies to assist ... More
A Comment on the Infra-Red Problem in the AdS/CFT CorrespondenceSep 27 2007In this note we report on some recent progress in proving the AdS/CFT correspondence for quantum fields using rigorously defined Euclidean path integrals. We also comment on the infra-red problem in the AdS/CFT correspondence and argue that it is different ... More
New Moduli for Banach SpacesSep 06 2016Modifying the moduli of supporting convexity and supporting smoothness, we introduce new moduli for Banach spaces which occur, e.g., as lengths of catheti of right-angled triangles (defined via so-called quasi-orthogonality). These triangles have two ... More
Controllability of NLS in the vicinity of solitary wave solutionsAug 05 2006Local exact controllability of the 1D NLS (subject to zero boundary conditions) with distributed control is shown to hold in a $H^1$--neighbourhood of the nonlinear ground state. The Hilbert Uniqueness Method (HUM), due to J.-L. Lions, is applied to the ... More
Redheffer representations and relaxed commutant liftingJun 04 2009Oct 23 2009It is well known that the solutions of a (relaxed) commutant lifting problem can be described via a linear fractional representation of the Redheffer type. The coefficients of such Redheffer representations are analytic operator-valued functions defined ... More
Second order approximations for limit order booksAug 24 2017Mar 02 2018In this paper we derive a second order approximation for an infinite dimensional limit order book model, in which the dynamics of the incoming order flow is allowed to depend on the current market price as well as on a volume indicator (e.g.~the volume ... More
Involutes of Polygons of Constant Width in Minkowski PlanesJun 12 2014Jul 02 2015Consider a convex polygon P in the plane, and denote by U a homothetical copy of the vector sum of P and (-P). Then the polygon U, as unit ball, induces a norm such that, with respect to this norm, P has constant Minkowskian width. We define notions like ... More
Geometry of simplices in Minkowski spacesOct 12 2017There are many problems and configurations in Euclidean geometry that were never extended to the framework of (normed or) finite dimensional real Banach spaces, although their original versions are inspiring for this type of generalization, and the analogous ... More
New Modes of Nuclear ExcitationsSep 30 2013Oct 01 2013We present a theoretical approach based on density functional theory supplemented by a microscopic multi-phonon model which is applied for investigations of pygmy resonances and other excitations of different multipolarities in stable and exotic nuclei. ... More
Observation of an anomalous heat current in GdPtBiOct 04 2018Aug 08 2019In condensed matter Weyl systems, it is predicted that the generation of a heat current by the mixed axial-gravitational anomaly leads to a negative magnetothermal resistivity (MTR), locked to the parallel alignment of the applied temperature gradient ... More
Illiquidity and Derivative ValuationDec 31 2008In illiquid markets, option traders may have an incentive to increase their portfolio value by using their impact on the dynamics of the underlying. We provide a mathematical framework within which to value derivatives under market impact in a multi-player ... More
Risk Minimization and Optimal Derivative Design in a Principal Agent GameOct 29 2007We consider the problem of Adverse Selection and optimal derivative design within a Principal-Agent framework. The principal's income is exposed to non-hedgeable risk factors arising, for instance, from weather or climate phenomena. She evaluates her ... More
A functional convergence theorem for interpolated Markov chains to an infinite dimensional diffusionAug 05 2016This paper is concerned with the derivation of a functional scaling limit theorem for a certain class of discrete time Markov chains, each consisting of a one dimensional reference process and an $L^2_{loc}$-valued volume process, for which the conditional ... More
Sources of negative differential resistance in electric nanotransportFeb 26 2010Apr 12 2010A negative differential resistance (NDR) in the nanotransport is often ascribed to electron correlations. We present a simple example which demonstrates that finite electrode bandwidths and energy dependent electrode density of states are responsible ... More
Studying the single--electron transistor by photoionizationNov 17 2008Mar 16 2009We present theoretical results demonstrating that photoionization can be a useful tool for investigating single--electron transistors. Suggestions are given on how to conduct experiments using photoionization alone or in combination with transport measurements. ... More
The Superluminal Tunneling StoryApr 10 2013Since 1992 experimental evidence of superluminal (faster than light, FTL) signals are causing much excitement in the physical community and in the media. Superluminal signal velocity and zero time tunneling was first observed in an analog tunneling experiment ... More
The return of the bow shockDec 04 2013Recently it has been discussed whether a bow shock ahead of the heliospheric stagnation region does exist or not. This discussion was triggered by measurements indicating that the Alfv\'en speed and that of fast magnetosonic waves are higher than the ... More
DETOx: Towards Optimal Software-based Soft-Error Detector ConfigurationsAug 22 2016Application developers often place executable assertions -- equipped with program-specific predicates -- in their system, targeting programming errors. However, these detectors can detect data errors resulting from transient hardware faults in main memory ... More