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Results for "Justus Bogner"

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Assuring the Evolvability of Microservices: Insights into Industry Practices and ChallengesJun 12 2019While Microservices promise several beneficial characteristics for sustainable long-term software evolution, little empirical research covers what concrete activities industry applies for the evolvability assurance of Microservices and how technical debt ... More
From Monolith to Microservices: A Classification of Refactoring ApproachesJul 26 2018Jan 24 2019While the recently emerged Microservices architectural style is widely discussed in literature, it is difficult to find clear guidance on the process of refactoring legacy applications. The importance of the topic is underpinned by high costs and effort ... More
Microservices Migration in Industry: Intentions, Strategies, and ChallengesJun 11 2019To remain competitive in a fast changing environment, many companies started to migrate their legacy applications towards a Microservices architecture. Such extensive migration processes require careful planning and consideration of implications and challenges ... More
Algebraic characterization of differential operators of Calabi-Yau typeApr 19 2013We give an algebraic characterization of Picard-Fuchs operators attached to families of Calabi-Yau manifolds with a point of maximally unipotent monodromy and discuss possibilities for their differential Galois groups.
MPL - a program for computations with iterated integrals on moduli spaces of curves of genus zeroOct 14 2015We introduce the computer program MPL for computations with homotopy invariant iterated integrals on moduli spaces $\mathcal{M}_{0,n}$ of curves of genus 0 with $n$ ordered marked points. The program is an implementation of the algorithms presented in ... More
Generalizations of polylogarithms for Feynman integralsMar 01 2016In this talk, we discuss recent progress in the application of generalizations of polylogarithms in the symbolic computation of multi-loop integrals. We briefly review the Maple program MPL which supports a certain approach for the computation of Feynman ... More
Density Matrix Renormalization for Model Reduction in Nonlinear DynamicsJul 30 2007Aug 29 2007We present a novel approach for model reduction of nonlinear dynamical systems based on proper orthogonal decomposition (POD). Our method, derived from Density Matrix Renormalization Group (DMRG), provides a significant reduction in computational effort ... More
Feynman integrals and iterated integrals on moduli spaces of curves of genus zeroAug 08 2014Mar 27 2015This paper describes algorithms for the exact symbolic computation of period integrals on moduli spaces $\mathcal{M}_{0,n}$ of curves of genus $0$ with $n$ ordered marked points, and applications to the computation of Feynman integrals.
Active and Transfer Learning of Grasps by Sampling from DemonstrationNov 19 2016We guess humans start acquiring grasping skills as early as at the infant stage by virtue of two key processes. First, infants attempt to learn grasps for known objects by imitating humans. Secondly, knowledge acquired during this process is reused in ... More
Grasp Learning by Sampling from DemonstrationNov 19 2016Robotic grasping traditionally relies on object features or shape information for learning new or applying already learned grasps. We argue however that such a strong reliance on object geometric information renders grasping and grasp learning a difficult ... More
MESA Models of the Evolutionary State of the Interacting Binary epsilon AurigaeMar 16 2018Using MESA code (Modules for Experiments in Stellar Astrophysics, version 9575), an evaluation was made of the evolutionary state of the epsilon Aurigae binary system (HD 31964, F0Iap + disk). We sought to satisfy several observational constraints: 1) ... More
Blowing up Feynman integralsJun 26 2008In this talk we discuss sector decomposition. This is a method to disentangle overlapping singularities through a sequence of blow-ups. We report on an open-source implementation of this algorithm to compute numerically the Laurent expansion of divergent ... More
Is there a Glass Transition in Planar Vortex Systems?Dec 13 2002The criteria for the existence of a glass transition in a planar vortex array with quenched disorder are studied. Applying a replica Bethe ansatz, we obtain for self-avoiding vortices the exact quenched average free energy and effective stiffness which ... More
Symbolic integration and multiple polylogarithmsSep 28 2012We review a method for the algebraic treatment of a family of functions which contains the multiple polylogarithms, with applications to the symbolic calculation of Feynman integrals.
Feynman graphs in perturbative quantum field theoryDec 22 2009In this talk we discuss mathematical structures associated to Feynman graphs. Feynman graphs are the backbone of calculations in perturbative quantum field theory. The mathematical structures -- apart from being of interest in their own right -- allow ... More
Periods and Feynman integralsNov 30 2007Mar 04 2009We consider multi-loop integrals in dimensional regularisation and the corresponding Laurent series. We study the integral in the Euclidean region and where all ratios of invariants and masses have rational values. We prove that in this case all coefficients ... More
Liquid-gas-solid flows with lattice Boltzmann: Simulation of floating bodiesJan 01 2012This paper presents a model for the simulation of liquid-gas-solid flows by means of the lattice Boltzmann method. The approach is built upon previous works for the simulation of liquid-solid particle suspensions on the one hand, and on a liquid-gas free ... More
Feynman graph polynomialsFeb 18 2010Apr 23 2010The integrand of any multi-loop integral is characterised after Feynman parametrisation by two polynomials. In this review we summarise the properties of these polynomials. Topics covered in this article include among others: Spanning trees and spanning ... More
Resolution of singularities for multi-loop integralsSep 26 2007Dec 03 2007We report on a program for the numerical evaluation of divergent multi-loop integrals. The program is based on iterated sector decomposition. We improve the original algorithm of Binoth and Heinrich such that the program is guaranteed to terminate. The ... More
High-momentum tails from low-momentum effective theoriesAug 08 2012In a recent work \cite{Anderson:2010aq}, Anderson \emph{et al.} used the renormalization group (RG) evolution of the momentum distribution to show that, under appropriate conditions, operator expectation values exhibit factorization in the two-nucleon ... More
Phase Description of Stochastic OscillationsJan 29 2013We introduce an invariant phase description of stochastic oscillations by generalizing the concept of standard isophases. The average isophases are constructed as sections in the state space, having a constant mean first return time. The approach allows ... More
Effective phase description of noise-perturbed and noise-induced oscillationsJun 16 2010An effective description of a general class of stochastic phase oscillators is presented. For this, the effective phase velocity is defined either by invariant probability density or via first passage times. While the first approach exhibits correct frequency ... More
An Empirical Assessment of the Complexity and Realism of Synthetic Social Contact NetworksOct 06 2018Nov 20 2018We use multiple measures of graph complexity to evaluate the realism of synthetically-generated networks of human activity, in comparison with several stylized network models as well as a collection of empirical networks from the literature. The synthetic ... More
Effective phase dynamics of noise-induced oscillations in excitable systemsFeb 02 2010Oct 01 2010We develop an effective description of noise-induced oscillations based on deterministic phase dynamics. The phase equation is constructed to exhibit correct frequency and distribution density of noise-induced oscillations. In the simplest one-dimensional ... More
A novel Skill-based Programming Paradigm based on Autonomous Playing and Skill-centric TestingSep 18 2017We introduce a novel paradigm for robot pro- gramming with which we aim to make robot programming more accessible for unexperienced users. In order to do so we incorporate two major components in one single framework: autonomous skill acquisition by robotic ... More
Deferred Neural Rendering: Image Synthesis using Neural TexturesApr 28 2019The modern computer graphics pipeline can synthesize images at remarkable visual quality; however, it requires well-defined, high-quality 3D content as input. In this work, we explore the use of imperfect 3D content, for instance, obtained from photo-metric ... More
Symbolic integration of a product of two spherical bessel functions with an additional exponential and polynomial factorOct 27 2009Dec 16 2009We present a mathematica package that performs the symbolic calculation of integrals of the form \int^{\infty}_0 e^{-x/u} x^n j_{\nu} (x) j_{\mu} (x) dx where $j_{\nu} (x)$ and $j_{\mu} (x)$ denote spherical Bessel functions of integer orders, with $\nu ... More
Delocalization in Coupled Luttinger Liquids with ImpuritiesOct 12 2001Mar 22 2002We study effects of quenched disorder on coupled two-dimensional arrays of Luttinger liquids (LL) as a model for stripes in high-T_c compounds. In the framework of a renormalization-group analysis, we find that weak inter-LL charge-density-wave couplings ... More
Molecular recognition in a lattice model: An enumeration studyJan 05 2005Jan 10 2005We investigate the mechanisms underlying selective molecular recognition of single heteropolymers at chemically structured planar surfaces. To this end, we study systems with two-letter (HP) lattice heteropolymers by exact enumeration techniques. Selectivity ... More
The real radiation antenna functions for $S\rightarrow Q\bar{Q}gg$ at NNLO QCDSep 26 2013We analyze, in the antenna subtraction framework, the real radiation antenna functions for processes involving the production of a pair of heavy quarks and two gluons by an uncolored initial state at NNLO QCD. We provide explicit expressions for these ... More
Analytic continuation and numerical evaluation of the kite integral and the equal mass sunrise integralMay 24 2017Jul 12 2017We study the analytic continuation of Feynman integrals from the kite family, expressed in terms of elliptic generalisations of (multiple) polylogarithms. Expressed in this way, the Feynman integrals are functions of two periods of an elliptic curve. ... More
Drag correlation for dilute and moderately dense fluid-particle systems using the lattice Boltzmann methodJan 09 2014Oct 07 2014This paper presents a numerical study of flow through static random assemblies of monodisperse, spherical particles. A lattice Boltzmann approach based on a two relaxation time collision operator is used to obtain reliable predictions of the particle ... More
Task-Based Algorithm for Matrix Multiplication: A Step Towards Block-Sparse Tensor ComputingApr 20 2015Distributed-memory matrix multiplication (MM) is a key element of algorithms in many domains (machine learning, quantum physics). Conventional algorithms for dense MM rely on regular/uniform data decomposition to ensure load balance. These traits conflict ... More
IMU2Face: Real-time Gesture-driven Facial ReenactmentDec 18 2017We present IMU2Face, a gesture-driven facial reenactment system. To this end, we combine recent advances in facial motion capture and inertial measurement units (IMUs) to control the facial expressions of a person in a target video based on intuitive ... More
Active and Transfer Learning of Grasps by Kernel Adaptive MCMCNov 19 2016Human ability of both versatile grasping of given objects and grasping of novel (as of yet unseen) objects is truly remarkable. This probably arises from the experience infants gather by actively playing around with diverse objects. Moreover, knowledge ... More
25 years of CNNs: Can we compare to human abstraction capabilities?Jul 28 2016We try to determine the progress made by convolutional neural networks over the past 25 years in classifying images into abstractc lasses. For this purpose we compare the performance of LeNet to that of GoogLeNet at classifying randomly generated images ... More
Learning Abstract Classes using Deep LearningJun 17 2016Humans are generally good at learning abstract concepts about objects and scenes (e.g.\ spatial orientation, relative sizes, etc.). Over the last years convolutional neural networks have achieved almost human performance in recognizing concrete classes ... More
Microscopically-constrained Fock energy density functionals from chiral effective field theory. I. Two-nucleon interactionsMar 26 2010The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyme-like energy density functional (EDF) with density-dependent ... More
Nonuniversal Correlations and Crossover Effects in the Bragg-Glass Phase of Impure SuperconductorsNov 29 2000The structural correlation functions of a weakly disordered Abrikosov lattice are calculated in a functional RG-expansion in $d=4-\epsilon$ dimensions. It is shown, that in the asymptotic limit the Abrikosov lattice exhibits still quasi-long-range translational ... More
The sunrise integral around two and four space-time dimensions in terms of elliptic polylogarithmsOct 07 2015In this talk we discuss the solution for the sunrise integral around two and four space-time dimensions in terms of a generalised elliptic version of the multiple polylogarithms. In two space-time dimensions we obtain a sum of three elliptic dilogarithms. ... More
The sunrise integral and elliptic polylogarithmsJun 30 2016We summarize recent computations with a class of elliptic generalizations of polylogarithms, arising from the massive sunrise integral. For the case of arbitrary masses we obtain results in two and four space-time dimensions. The iterated integral structure ... More
Symbolic computation of the Hartree-Fock energy from a chiral EFT three-nucleon interaction at N$^2$LODec 16 2009We present the first of a two-part Mathematica notebook collection that implements a symbolic approach for the application of the density matrix expansion (DME) to the Hartree-Fock (HF) energy from a chiral effective field theory (EFT) three-nucleon interaction ... More
An improved density matrix expansion for spin-unsaturated nucleiOct 27 2009Apr 15 2010A current objective of low-energy nuclear theory is to build non-empirical nuclear energy density functionals (EDFs) from underlying inter-nucleon interactions and many-body perturbation theory (MBPT). The density matrix expansion (DME) of Negele and ... More
Non-Universal Quasi-Long Range Order in the Glassy Phase of Impure SuperconductorsMar 06 1999Jul 12 1999The structural correlation functions of a weakly disordered Abrikosov lattice are calculated for the first time in a systematic RG-expansion in d=4-\epsilon dimensions. It is shown, that in the asymptotic limit the Abrikosov lattice exhibits still quasi ... More
The two-loop sunrise integral around four space-time dimensions and generalisations of the Clausen and Glaisher functions towards the elliptic caseApr 13 2015We present the result for the finite part of the two-loop sunrise integral with unequal masses in four space-time dimensions in terms of the ${\mathcal O}(\varepsilon^0)$-part and the ${\mathcal O}(\varepsilon^1)$-part of the sunrise integral around two ... More
The two-loop sunrise graph with arbitrary massesFeb 27 2013We discuss the analytical solution of the two-loop sunrise graph with arbitrary non-zero masses in two space-time dimensions. The analytical result is obtained by solving a second-order differential equation. The solution involves elliptic integrals and ... More
Curvature estimation from a volume of fluid indicator function for the simulation of surface tension and wetting with a free surface lattice Boltzmann methodSep 25 2015Feb 10 2016The free surface lattice Boltzmann method (FSLBM) is a combination of the hydrodynamic lattice Boltzmann method (LBM) with a volume of fluid (VOF) interface apturing technique for the simulation of incompressible free surface flows. Capillary effects ... More
Low-momentum interaction in few-nucleon systemsMay 06 2004The effective low-momentum interaction Vlowk is applied to three- and four-nucleon systems. We investigate the 3H, 3He and 4He binding energies for a wide range of the momentum cutoffs. By construction, all low-energy two-body observables are cutoff-independent, ... More
In-Medium Similarity Renormalization Group for Open-Shell NucleiMar 12 2012We present a nonperturbative derivation of effective valence-shell Hamiltonians in the framework of the recently developed in-medium similarity renormalization group (IM-SRG). As a first application, we calculate the spectra of $p$- and $sd$-shell nuclei, ... More
The iterated structure of the all-order result for the two-loop sunrise integralDec 17 2015Mar 12 2016We present a method to compute the Laurent expansion of the two-loop sunrise integral with equal non-zero masses to arbitrary order in the dimensional regularisation $\varepsilon$. This is done by introducing a class of functions (generalisations of multiple ... More
The Elliptic SunriseOct 13 2015In this talk, we discuss our recent computation of the two-loop sunrise integral with arbitrary non-zero particle masses. In two space-time dimensions, we arrive at a result in terms of elliptic dilogarithms. Near four space-time dimensions, we obtain ... More
A walk on sunset boulevardJan 14 2016A walk on sunset boulevard can teach us about transcendental functions associated to Feynman diagrams. On this guided tour we will see multiple polylogarithms, differential equations and elliptic curves. A highlight of the tour will be the generalisation ... More
About a class of Calabi-Yau differential equationsOct 24 2013We explain an experimental method to find CY-type differential equations of order $3$ related to modular functions of genus zero. We introduce a similar class of Calabi-Yau differential equations of order $5$, show several examples and make a conjecture ... More
Predicting with limited data - Increasing the accuracy in VIS-NIR diffuse reflectance spectroscopy by SMOTEMar 15 2017Diffuse reflectance spectroscopy is a powerful technique to predict soil properties. It can be used in situ to provide data inexpensively and rapidly compared to the standard laboratory measurements. Because most spectral data bases contain air-dried ... More
Equivalence of model space techniques and the renormalization group for a separable model problemSep 26 2000Dec 15 2000Lee-Suzuki similarity transformations and Krencigowa-Kuo folded diagrams are two common methods used to derive energy independent model space effective interactions for nuclear many-body systems. We demonstrate that these methods are equivalent to a Renormalization ... More
Disorder Driven Lock-In Transitions of CDWs and Related StructuresAug 25 1999Thermal fluctuations are known to play an important role in low-dimensional systems which may undergo incommensurate-commensurate or (for an accidentally commensurate wavevector) lock-in transitions. In particular, an intermediate floating phase with ... More
In-Medium Similarity Renormalization Group for NucleiJun 18 2010May 24 2011We present a new ab-initio method that uses similarity renormalization group (SRG) techniques to continuously diagonalize nuclear many-body Hamiltonians. In contrast with applications of the SRG to two- and three-nucleon interactions in free space, we ... More
The two-loop sunrise graph in two space-time dimensions with arbitrary masses in terms of elliptic dilogarithmsMay 22 2014Sep 14 2014We present the two-loop sunrise integral with arbitrary non-zero masses in two space-time dimensions in terms of elliptic dilogarithms. We find that the structure of the result is as simple and elegant as in the equal mass case, only the arguments of ... More
Boundary Conditions for Free Interfaces with the Lattice Boltzmann MethodSep 19 2014Feb 16 2015In this paper we analyze the boundary treatment of the lattice Boltzmann method (LBM) for simulating 3D flows with free surfaces. The widely used free surface boundary condition of K\"orner et al. (2005) is shown to be first order accurate. The article ... More
Direct simulation of liquid-gas-solid flow with a free surface lattice Boltzmann methodDec 19 2017Direct numerical simulation of liquid-gas-solid flows is uncommon due to the considerable computational cost. As the grid spacing is determined by the smallest involved length scale, large grid sizes become necessary -- in particular if the bubble-particle ... More
Key bifurcations of bursting polyrhythms in 3-cell central pattern generatorsDec 28 2013We identify and describe the key qualitative rhythmic states in various 3-cell network motifs of a multifunctional central pattern generator (CPG). Such CPGs are neural microcircuits of cells whose synergetic interactions produce multiple states with ... More
Clustered Low-Rank Tensor Format: Introduction and Application to Fast Construction of Hartree-Fock ExchangeOct 05 2015Clustered Low Rank (CLR) framework for block-sparse and block-low-rank tensor representation and computation is described. The CLR framework depends on 2 parameters that control precision: one controlling the CLR block rank truncation and another that ... More
Skill Learning by Autonomous Robotic Playing using Active Learning and CreativityJun 26 2017We treat the problem of autonomous acquisition of manipulation skills where problem-solving strategies are initially available only for a narrow range of situations. We propose to extend the range of solvable situations by autonomous playing with the ... More
Predicting the Computational Cost of Deep Learning ModelsNov 28 2018Deep learning is rapidly becoming a go-to tool for many artificial intelligence problems due to its ability to outperform other approaches and even humans at many problems. Despite its popularity we are still unable to accurately predict the time it will ... More
Weighted-ensemble Brownian dynamics simulation: Sampling of rare events in non-equilibrium systemsMar 16 2013We provide an algorithm based on weighted-ensemble (WE) methods, to accurately sample systems at steady state. Applying our method to different one- and two-dimensional models, we succeed to calculate steady state probabilities of order $10^{-300}$ and ... More
Action Representations in Robotics: A Taxonomy and Systematic ClassificationSep 12 2018Understanding and defining the meaning of "action" is substantial for robotics research. This becomes utterly evident when aiming at equipping autonomous robots with robust manipulation skills for action execution. Unfortunately, to this day we still ... More
Qualitative and Quantitative Stability Analysis of Penta-rhythmic CircuitsSep 15 2015Inhibitory circuits of relaxation oscillators are often-used models for the dynamics of biological networks. We present a qualitative and quantitative stability analysis of such a circuit constituted by three reciprocally coupled oscillators of a Fitzhugh-Nagumo ... More
Stochastic Methods for Zero Energy Quantum ScatteringMar 10 1997We investigate the use of stochastic methods for zero energy quantum scattering based on a path integral approach. With the application to the scattering of a projectile from a nuclear many body target in mind, we use the potential scattering of a particle ... More
Optimal Phase Description of Chaotic OscillatorsOct 19 2011We introduce an optimal phase description of chaotic oscillations by generalizing the concept of isochrones. On chaotic attractors possessing a general phase description, we define the optimal isophases as Poincar\'e surfaces showing return times as constant ... More
BSM Kaon Mixing at the Physical PointFeb 27 2017We present new preliminary results for bag parameters and ratios of the BSM kaon mixing operators measured at the physical point. The results are obtained from simulations of domain wall fermion QCD with 2+1 flavours with an Iwasaki gauge, and now include ... More
IGNOR: Image-guided Neural Object RenderingNov 26 2018We propose a new learning-based novel view synthesis approach for scanned objects that is trained based on a set of multi-view images. Instead of using texture mapping or hand-designed image-based rendering, we directly train a deep neural network to ... More
From low-momentum interactions to nuclear structureDec 17 2009Jun 11 2010We present an overview of low-momentum two-nucleon and many-body interactions and their use in calculations of nuclei and infinite matter. The softening of phenomenological and effective field theory (EFT) potentials by renormalization group (RG) transformations ... More
Comment on "Problems in the derivations of the renormalization group equation for the low momentum nucleon interactions"Jun 09 2008The criticisms in manuscript arXiv:0803.4371 do not change the renormalization group equation for the "$\vlowk$" interaction nor do they affect any results in the literature. Several other potentially misleading statements about low-momentum interactions ... More
Differential equations for Feynman integrals beyond multiple polylogarithmsDec 10 2017Dec 13 2017Differential equations are a powerful tool to tackle Feynman integrals. In this talk we discuss recent progress, where the method of differential equations has been applied to Feynman integrals which are not expressible in terms of multiple polylogarithms. ... More
Low-momentum interactions in three- and four-nucleon scatteringFeb 11 2008Low momentum two-nucleon interactions obtained with the renormalization group method and the similarity renormalization group method are used to study the cutoff dependence of low energy 3N and 4N scattering observables. The residual cutoff dependence ... More
Scalable Task-Based Algorithm for Multiplication of Block-Rank-Sparse MatricesSep 01 2015Oct 09 2015A task-based formulation of Scalable Universal Matrix Multiplication Algorithm (SUMMA), a popular algorithm for matrix multiplication (MM), is applied to the multiplication of hierarchy-free, rank-structured matrices that appear in the domain of quantum ... More
Hierarchical Haptic Manipulation for Complex Skill LearningMar 02 2016In complex manipulation scenarios (e.g. tasks requiring complex interaction of two hands or in-hand manipulation), generaliza- tion is a hard problem. Current methods still either require a substantial amount of (supervised) training data and / or strong ... More
Robotic Playing for Hierarchical Complex Skill LearningMar 02 2016Aug 13 2017In complex manipulation scenarios (e.g. tasks requiring complex interaction of two hands or in-hand manipulation), generalization is a hard problem. Current methods still either require a substantial amount of (supervised) training data and / or strong ... More
Monte Carlo calculations for the hard PomeronOct 29 1996Starting from the same input as the standard BFKL Pomeron, we directly calculate the ``hard'' Pomeron as a gluonic ladder by using Monte Carlo methods. We reproduce the characteristic features of the the BFKL Pomeron and are now also able to evaluate ... More
Chemokinetic search with one bit of memoryApr 24 2019The benefit of chemokinesis in motile cells, i.e., the regulation of speed and directional persistence as function of spatial position by non-directional cues, is not well understood. We develop a theory of chemokinetic search agents that can detect the ... More
FaceVR: Real-Time Facial Reenactment and Eye Gaze Control in Virtual RealityOct 11 2016We introduce FaceVR, a novel method for gaze-aware facial reenactment in the Virtual Reality (VR) context. The key component of FaceVR is a robust algorithm to perform real-time facial motion capture of an actor who is wearing a head-mounted display (HMD), ... More
Proceedings of the 2nd Workshop on Robots in Clutter: Preparing robots for the real world (Berlin, 2013)Jun 15 2013This volume represents the proceedings of the 2nd Workshop on Robots in Clutter: Preparing robots for the real world, held June 27, 2013, at the Robotics: Science and Systems conference in Berlin, Germany.
Emergence and coherence of oscillations in star networks of stochastic excitable elementsDec 04 2015We study the emergence and coherence of stochastic oscillations in star networks of excitable elements in which peripheral nodes receive independent random inputs. A biophysical model of a distal branch of sensory neuron in which peripheral nodes of Ranvier ... More
Coordination via predictive assistants: time series algorithms and game-theoretic analysisMar 16 2018Oct 05 2018We study data-driven assistants that provide congestion forecasts to users of crowded facilities (roads, cafeterias, etc.), to support coordination between them. Having multiple agents and feedback loops from predictions to outcomes, new problems arise ... More
Weinberg Eigenvalues and Pairing with Low-Momentum PotentialsSep 05 2007The nonperturbative nature of nucleon-nucleon interactions evolved to low momentum has recently been investigated in free space and at finite density using Weinberg eigenvalues as a diagnostic. This analysis is extended here to the in-medium eigenvalues ... More
Low-momentum interactions with smooth cutoffsSep 01 2006Nucleon-nucleon potentials evolved to low momentum, which show great promise in few- and many-body calculations, have generally been formulated with a sharp cutoff on relative momenta. However, a sharp cutoff has technical disadvantages and can cause ... More
Low momentum nucleon-nucleon potentials with half-on-shell T-matrix equivalenceApr 24 2002We study a method by which realistic nucleon-nucleon potentials V_NN can be reduced, in a physically equivalent way, to an effective low-momentum potential V-low-k confined within a cut-off momentum k-cut. Our effective potential is obtained using the ... More
Applying the Density Matrix Expansion with Coordinate-Space Chiral InteractionsNov 11 2016We apply the density matrix expansion (DME) at Hartree-Fock level with long-range chiral effective field theory interactions defined in coordinate space up to next-to-next-to-leading order. We consider chiral potentials both with and without explicit ... More
Test of Replica Theory: Thermodynamics of 2D Model Systems with Quenched DisorderSep 05 2003We study the statistics of thermodynamic quantities in two related systems with quenched disorder: A (1+1)-dimensional planar lattice of elastic lines in a random potential and the 2-dimensional random bond dimer model. The first system is examined by ... More
The Magnus expansion and the in-medium similarity renormalization groupJul 24 2015Aug 03 2015We present an improved variant of the in-medium similarity renormalization group (IM-SRG) based on the Magnus expansion. In the new formulation, one solves flow equations for the anti-hermitian operator that, upon exponentiation, yields the unitary transformation ... More
Effective Interactions for the Three-Body ProblemApr 09 2004The three-body energy-dependent effective interaction given by the Bloch-Horowitz (BH) equation is evaluated for various shell-model oscillator spaces. The results are applied to the test case of the three-body problem (triton and He3), where it is shown ... More
The number of master integrals as Euler characteristicSep 10 2018We give a brief introduction to a parametric approach for the derivation of shift relations between Feynman integrals and a result on the number of master integrals. The shift relations are obtained from parametric annihilators of the Lee-Pomeransky polynomial ... More
Free Surface Lattice Boltzmann with Enhanced Bubble ModelApr 06 2016This paper presents an enhancement to the free surface lattice Boltzmann method (FSLBM) for the simulation of bubbly flows including rupture and breakup of bubbles. The FSLBM uses a volume of fluid approach to reduce the problem of a liquid-gas two-phase ... More
The kite integral to all orders in terms of elliptic polylogarithmsJul 06 2016We show that the Laurent series of the two-loop kite integral in $D=4-2\varepsilon$ space-time dimensions can be expressed in each order of the series expansion in terms of elliptic generalisations of (multiple) polylogarithms. Using differential equations ... More
Similarity Renormalization Group for Nucleon-Nucleon InteractionsNov 13 2006Jun 04 2007The similarity renormalization group (SRG) is based on unitary transformations that suppress off-diagonal matrix elements, forcing the hamiltonian towards a band-diagonal form. A simple SRG transformation applied to nucleon-nucleon interactions leads ... More
Localization-dependent charge separation efficiency at an organic/inorganic hybrid interfaceDec 01 2014Jan 05 2016By combining complementary optical techniques, photoluminescence and time-resolved excited state absorption, we achieve a comprehensive picture of the relaxation processes in the organic/inorganic hybrid system SP6/ZnO. We identify two long-lived excited ... More
Nuclear matter from chiral low-momentum interactionsMar 19 2009Nuclear matter calculations based on low-momentum interactions derived from chiral nucleon-nucleon and three-nucleon effective field theory interactions and fit only to few-body data predict realistic saturation properties with controlled uncertainties. ... More
Convergence of the Born Series with Low-Momentum InteractionsFeb 22 2006May 17 2006The nonperturbative nature of nucleon-nucleon interactions as a function of a momentum cutoff is studied using Weinberg eigenvalues as a diagnostic. This investigation extends an earlier study of the perturbative convergence of the Born series to partial ... More
Comment on "A Bragg glass phase in the vortex lattice of a type II superconductor"Oct 29 2001Oct 30 2001In a recent letter Klein et al. [Nature 413, 404 (2001); cond-mat/0110018] provide experimental evidence for the existence of the Bragg glass phase in impure type II superconductors. Here we show that a more complete consideration of recent theoretical ... More
Three-Body Forces Produced by a Similarity Renormalization Group Transformation in a Simple ModelAug 12 2007Oct 25 2007A simple class of unitary renormalization group transformations that force hamiltonians towards a band-diagonal form produce few-body interactions in which low- and high-energy states are decoupled, which can greatly simplify many-body calculations. One ... More