Results for "Peter Bubenik"

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Models and van Kampen theorems for directed homotopy theoryOct 22 2008We study topological spaces with a distinguished set of paths, called directed paths. Since these directed paths are generally not reversible, the directed homotopy classes of directed paths do not assemble into a groupoid, and there is no direct analog ... More
Context for models of concurrencyAug 29 2006Many categories have been used to model concurrency. Using any of these, the challenge is to reduce a given model to a smaller representation which nevertheless preserves the relevant computer-scientific information. That is, one wants to replace a given ... More
Statistical topological data analysis using persistence landscapesJul 27 2012Jan 23 2015We define a new topological summary for data that we call the persistence landscape. Since this summary lies in a vector space, it is easy to combine with tools from statistics and machine learning, in contrast to the standard topological summaries. Viewed ... More
Densities for random balanced samplingAug 29 2006A random balanced sample (RBS) is a multivariate distribution with n components X_1,...,X_n, each uniformly distributed on [-1, 1], such that the sum of these components is precisely 0. The corresponding vectors X lie in an (n-1)-dimensional polytope ... More
Categorification of persistent homologyMay 16 2012Jan 08 2014We redevelop persistent homology (topological persistence) from a categorical point of view. The main objects of study are diagrams, indexed by the poset of real numbers, in some target category. The set of such diagrams has an interleaving distance, ... More
Cell attachments and the homology of loop spaces and differential graded algebrasJan 17 2006The cell-attachment problem, perhaps first studied by J.H.C. Whitehead around 1940, asks one to describe the effect of attaching one or more cells, on the algebraic invariants of a topological space. This thesis studies the effect of cell attachments ... More
Free and semi-inert cell attachmentsDec 19 2003Let $Y$ be the space obtained by attaching a finite-type wedge of cells to a simply-connected, finite-type CW-complex. We introduce the free and semi-inert conditions on the attaching map which broadly generalize the previously studied inert condition. ... More
The persistence landscape and some of its propertiesOct 11 2018Jan 26 2019Persistence landscapes map persistence diagrams into a function space, which may often be taken to be a Banach space or even a Hilbert space. In the latter case, it is a feature map and there is an associated kernel. The main advantage of this summary ... More
Separated Lie models and the homotopy Lie algebraJun 21 2004May 07 2007A simply connected topological space X has homotopy Lie algebra $\pi_*(\Omega X) \tensor \Q$. Following Quillen, there is a connected differential graded free Lie algebra (dgL) called a Lie model, which determines the rational homotopy type of X, and ... More
Simplicial models for concurrencyNov 30 2010Mar 29 2011We model both concurrent programs and the possible executions from one state to another in a concurrent program using simplices. The latter are calculated using necklaces of simplices in the former.
Embeddings of Persistence Diagrams into Hilbert SpacesMay 11 2019Since persistence diagrams do not admit an inner product structure, a map into a Hilbert space is needed in order to use kernel methods. It is natural to ask if such maps necessarily distort the metric on persistence diagrams. We show that persistence ... More
A persistence landscapes toolbox for topological statisticsDec 31 2014Aug 28 2015Topological data analysis provides a multiscale description of the geometry and topology of quantitative data. The persistence landscape is a topological summary that can be easily combined with tools from statistics and machine learning. We give efficient ... More
Topological spaces of persistence modules and their propertiesFeb 22 2018Oct 25 2018Persistence modules are a central algebraic object arising in topological data analysis. The notion of interleaving provides a natural way to measure distances between persistence modules. We consider various classes of persistence modules, including ... More
Homological Algebra for Persistence ModulesMay 14 2019We develop some aspects of the homological algebra of persistence modules, in both the one-parameter and multi-parameter settings, considered as either sheaves or graded modules. The two theories are different. We consider the graded module and sheaf ... More
Stabilizing the output of persistent homology computationsDec 05 2015We propose a general technique for extracting a larger set of stable information from persistent homology computations than is currently done. The persistent homology algorithm is generally seen as a procedure which starts with a filtered complex and ... More
A model category for local po-spacesJun 17 2005Jan 10 2006Locally partial-ordered spaces (local po-spaces) have been used to model concurrent systems. We provide equivalences for these spaces by constructing a model category containing the category of local po-spaces. We show the category of simplicial presheaves ... More
A statistical approach to persistent homologyJul 25 2006Aug 01 2007Assume that a finite set of points is randomly sampled from a subspace of a metric space. Recent advances in computational topology have provided several approaches to recovering the geometric and topological properties of the underlying space. In this ... More
Graph products of spheres, associative graded algebras and Hilbert seriesJan 28 2009Mar 08 2010Given a finite, simple, vertex-weighted graph, we construct a graded associative (non-commutative) algebra, whose generators correspond to vertices and whose ideal of relations has generators that are graded commutators corresponding to edges. We show ... More
Wasserstein distance for generalized persistence modules and abelian categoriesSep 25 2018In persistence theory and practice, measuring distances between modules is central. The Wasserstein distances are the standard family of L^p distances for persistence modules. They are defined in a combinatorial way for discrete invariants called persistence ... More
Graded persistence diagrams and persistence landscapesApr 29 2019We introduce a refinement of the persistence diagram, the graded persistence diagram. It is a sequence of diagrams whose sum is the persistence diagram. The points in the k-th graded persistence diagram are signed and are the local maxima and minima, ... More
Stabilizing the unstable output of persistent homology computationsDec 05 2015Oct 25 2018We propose a general technique for extracting a larger set of stable information from persistent homology computations than is currently done. The persistent homology algorithm is usually viewed as a procedure which starts with a filtered complex and ... More
Min-type Morse theory for configuration spaces of hard spheresAug 15 2011Aug 29 2011We study configuration spaces of hard spheres in a bounded region. We develop a general Morse-theoretic framework, and show that mechanically balanced configurations play the role of critical points. As an application, we find the precise threshold radius ... More
Higher interpolation and extension for persistence modulesMar 24 2016The use of topological persistence in contemporary data analysis has provided considerable impetus for investigations into the geometric and functional-analytic structure of the space of persistence modules. In this paper, we isolate a coherence criterion ... More
Higher interpolation and extension for persistence modulesMar 24 2016Mar 20 2017The use of topological persistence in contemporary data analysis has provided considerable impetus for investigations into the geometric and functional-analytic structure of the space of persistence modules. In this paper, we isolate a coherence criterion ... More
Interleaving and Gromov-Hausdorff distanceJul 19 2017Apr 26 2018One of the central notions to emerge from the study of persistent homology is that of interleaving distance. It has found recent applications in symplectic and contact geometry, sheaf theory, computational geometry, and phylogenetics. Here we present ... More
Metrics for generalized persistence modulesDec 13 2013Feb 05 2015We consider the question of defining interleaving metrics on generalized persistence modules over arbitrary preordered sets. Our constructions are functorial, which implies a form of stability for these metrics. We describe a large class of examples, ... More
Statistical topology via Morse theory, persistence and nonparametric estimationAug 25 2009Mar 04 2010In this paper we examine the use of topological methods for multivariate statistics. Using persistent homology from computational algebraic topology, a random sample is used to construct estimators of persistent homology. This estimation procedure can ... More
Closed Model Categories for Presheaves of Simplicial Groupoids and Presheaves of 2-GroupoidsJan 06 2003Feb 05 2009It is shown that the category of presheaves of simplicial groupoids and the category of presheaves of 2-groupoids have Quillen closed model structures. Furthermore, their homotopy categories are equivalent to the homotopy categories of simplicial presheaves ... More
Using persistent homology and dynamical distances to analyze protein bindingDec 03 2014Jul 30 2015Persistent homology captures the evolution of topological features of a model as a parameter changes. The most commonly used summary statistics of persistent homology are the barcode and the persistence diagram. Another summary statistic, the persistence ... More
Proceedings of the Twenty-Sixth Conference on Uncertainty in Artificial Intelligence (2010)May 11 2012Aug 28 2014This is the Proceedings of the Twenty-Sixth Conference on Uncertainty in Artificial Intelligence, which was held on Catalina Island, CA, July 8 - 11 2010.
Aspects of workDec 08 2015Various approaches of defining and determining work performed on a quantum system are compared. Any operational definition of work, however, must allow for two facts, first, that work characterizes a process rather than an instantaneous state of a system, ... More
Phi, Omega and Rho production from deconfined matter in relativistic heavy ion collisions at CERN SPSSep 29 1999We investigate the production of the Phi meson and the Omega baryon which interact weakly with hot hadronic matter, and thus their spectra reflect the early stage of the heavy ion collisions. Our analysis shows that the hadronization temperature, T_had, ... More
Regret and Jeffreys Integrals in Exp. FamiliesMar 31 2009The problem of whether minimax redundancy, minimax regret and Jeffreys integrals are finite or infinite are discussed.
General Solutions for Multispin Two-Time Correlation and Response Functions in the Glauber-Ising ChainJul 09 2003The kinetic Glauber-Ising spin chain is one of the very few exactly solvable models of non-equilibrium statistical mechanics. Nevertheless, existing solutions do not yield tractable expressions for two-time correlation and response functions of observables ... More
Changing gears: Isospectrality via eigenderivative transplantationSep 11 2015We introduce a new method for constructing isospectral quantum graphs that is based on transplanting derivatives of eigenfunctions. We also present simple digraphs with the same reversing zeta function, which generalizes the Bartholdi zeta function to ... More
A spatial model for selection and cooperationMar 02 2016Nov 02 2016We study the evolution of cooperation in an interacting particle system with two types. The model we investigate is an extension of a two-type biased voter model. One type (called defector) has a (positive) bias $\alpha$ with respect to the other type ... More
A spatial model for selection and cooperationMar 02 2016Oct 11 2016We study the evolution of cooperation in an interacting particle system with two types. The model we investigate is an extension of a two-type biased voter model. One type (called defector) has a (positive) bias $\alpha$ with respect to the other type ... More
Structural Intervention Distance (SID) for Evaluating Causal GraphsJun 05 2013Apr 07 2014Causal inference relies on the structure of a graph, often a directed acyclic graph (DAG). Different graphs may result in different causal inference statements and different intervention distributions. To quantify such differences, we propose a (pre-) ... More
Spectral asymptotics of the Laplacian on supercritical bond-percolation graphsJun 21 2005Jul 03 2007We investigate Laplacians on supercritical bond-percolation graphs with different boundary conditions at cluster borders. The integrated density of states of the Dirichlet Laplacian is found to exhibit a Lifshits tail at the lower spectral edge, while ... More
Statistical Cosmology with Quadratic Density FieldsAug 15 2002Primordial fluctuations in the cosmic density are usually assumed to take the form of a Gaussian random field that evolves under the action of gravitational instability. In the early stages, while they have low amplitude, the fluctuations grow linearly. ... More
Galaxy-galaxy-galaxy lensing: Third-order correlations between the galaxy and mass distributions in the UniverseFeb 25 2005Galaxy-galaxy lensing (GGL) measures the 2-point cross-correlation between galaxies and mass in the Universe. In this work we seek to generalise this effect by considering the third-order correlations between galaxies and mass: galaxy-galaxy-galaxy lensing. ... More
Open system trajectories specify fluctuating work but not heatMay 24 2016Aug 26 2016Based on the explicit knowledge of a Hamiltonian of mean force, the classical statistical mechanics and equilibrium thermodynamics of open systems in contact with a thermal environment at arbitrary interaction strength can be formulated. Even though the ... More
Aging in One-Dimensional Coagulation-Diffusion Processes and the Fredrickson-Andersen ModelFeb 26 2007We analyse the aging dynamics of the one-dimensional Fredrickson-Andersen (FA) model in the nonequilibrium regime following a low temperature quench. Relaxation then effectively proceeds via diffusion limited pair coagulation (DLPC) of mobility excitations. ... More
Observable Dependent Quasi-Equilibrium in Slow DynamicsMay 31 2004Apr 18 2005We present examples demonstrating that quasi-equilibrium fluctuation-dissipation behavior at short time differences is not a generic feature of systems with slow non-equilibrium dynamics. We analyze in detail the non-equilibrium fluctuation-dissipation ... More
Identifiability of Gaussian structural equation models with equal error variancesMay 11 2012Aug 28 2013We consider structural equation models in which variables can be written as a function of their parents and noise terms, which are assumed to be jointly independent. Corresponding to each structural equation model, there is a directed acyclic graph describing ... More
Some limit results for Markov chains indexed by treesJun 14 2014We consider a sequence of Markov chains $(\mathcal X^n)_{n=1,2,...}$ with $\mathcal X^n = (X^n_\sigma)_{\sigma\in\mathcal T}$, indexed by the full binary tree $\mathcal T = \mathcal T_0 \cup \mathcal T_1 \cup ...$, where $\mathcal T_k$ is the $k$th generation ... More
Percolation HamiltoniansFeb 26 2010Jan 09 2011There has been quite some activity and progress concerning spectral asymptotics of random operators that are defined on percolation subgraphs of different types of graphs. In this short survey we record some of these results and explain the necessary ... More
A spatial model for selection and cooperationMar 02 2016We study the evolution of cooperation in an interacting particle system with two types. The model we investigate is an extension of a two-type biased voter model. One type (called defector) has a (positive) bias $\alpha$ with respect to the other type ... More
The Tasaki-Crooks quantum fluctuation theoremMay 09 2007Starting out from the recently established quantum correlation function expression of the characteristic function for the work performed by a force protocol on the system [cond-mat/0703213] the quantum version of the Crooks fluctuation theorem is shown ... More
Studying Attractor Symmetries by Means of Cross Correlation SumsMay 02 1996We use the cross correlation sum introduced recently by H. Kantz to study symmetry properties of chaotic attractors. In particular, we apply it to a system of six coupled nonlinear oscillators which was shown by Kroon et al. to have attractors with several ... More
Pion-Nucleon Distribution AmplitudesSep 12 2007This is a short presentation of the results for the pion-nucleon distribution amplitudes which are expressed in terms of the nucleon distribution amplitudes with the help of current algebra. Everything is considered to be at threshold.
Typical fast thermalization processes in closed many-body systemsMar 02 2016Lack of knowledge about the detailed many-particle motion on the microscopic scale is a key issue in any theoretical description of a macroscopic experiment. For systems at or close to thermal equilibrium, statistical mechanics provides a very successful ... More
The minimum principle from a Hamiltonian point of viewDec 28 1997Let G be a complex Lie group, G_R a real form of G and X a G_R-stable domain of holomorphy in a complex G-manifold. If there is a G_R-invariant strictly plurisubharmonic function on X which has certain exhaustion properties, then we show that the extended ... More
On removable sets for Sobolev spaces in the planeNov 26 1991Let $K$ be a compact subset of $\bar{\bold C} ={\bold R}^2$ and let $K^c$ denote its complement. We say $K\in HR$, $K$ is holomorphically removable, if whenever $F:\bar{\bold C} \to\bar{\bold C}$ is a homeomorphism and $F$ is holomorphic off $K$, then ... More
Bloch-type conjectures and an example of a threefold of general typeFeb 11 2009The hypothetical existence of a good theory of mixed motives predicts many deep phenomena related to algebraic cycles. One of these, a generalization of Bloch's conjecture says that "small Hodge diamonds" go with "small Chow groups". Voisin's method (which ... More
The SKA and the Unknown UnknownsJun 29 2015As new scientists and engineers join the SKA project and as the pressures come on to maintain costs within a chosen envelope it is worth restating and updating the rationale for the 'Exploration of the Unknown' (EoU). Maintaining an EoU philosophy will ... More
Weakly polydisperse systems: Perturbative phase diagrams that include the critical regionSep 10 2007Mar 03 2008The phase behaviour of a weakly polydisperse system, such as a colloid with a small spread of particle sizes, can be related perturbatively to that of its monodisperse counterpart. I show how this approach can be generalized to remain well-behaved near ... More
Gaussian Process Regression with Mismatched ModelsJun 22 2001Learning curves for Gaussian process regression are well understood when the `student' model happens to match the `teacher' (true data generation process). I derive approximations to the learning curves for the more generic case of mismatched models, ... More
An explicit solution of a non-linear quadratic constrained stochastic control problem with an application to optimal liquidation in dark pools with adverse selectionApr 11 2012Apr 26 2013We study a constrained stochastic control problem with jumps; the jump times of the controlled process are given by a Poisson process. The cost functional comprises quadratic components for an absolutely continuous control and the controlled process and ... More
Interacting Random Trajectories: a DiscussionNov 29 2016Shared control fuses operator inputs and autonomy inputs into a single command. However, if environmental or operator predictions are multimodal, state of the art approaches are suboptimal with respect to safety, efficiency, and operator-autonomy agreement: ... More
The exclusive Drell-Yan process and deeply virtual pion productionNov 05 2016In this talk it is reported on analyses of l p -> l pi+ n and pi- p -> l+ l- n within the handbag approach. It is argued that recent measurements of hard pion production performed by HERMES and CLAS clearly indicate the occurrence of strong contributions ... More
Representation stability for filtrations of Torelli groupsAug 23 2016We show, rational $\mathsf{VIC}_{\mathbb Q}$-modules and $\mathsf{SI}_{\mathbb Q}$-modules that are generated in finite degree are multiplicity stable. We use this to prove two conjectures of Church and Farb, which state that the quotients of the lower ... More
Simulating phase transitions by means of quasi static state changes: the capabilities of the time dependent Van der Waals equation of stateSep 29 2016The Van der Waals equation (VdW-EoS) is a prototype equation of state for realistic systems, because it contains the excluded volume and the particle interactions. Additionally, the simulated annealing (and the similar simulated compressing) approach ... More
Local Convergence of the Heavy-ball Method and iPiano for Non-convex OptimizationJun 29 2016Oct 18 2016A local convergence result for abstract descent methods is proved: The sequence of iterates is attracted by a local (or global) minimum, stays in its neighborhood and converges within this neighborhood. This result allows algorithms to exploit local properties ... More
Decay of density waves in coupled one-dimensional many-body-localized systemsJun 15 2016Oct 11 2016The behavior of coupled disordered one-dimensional systems, as modelled by identical fermionic Hubbard chains with the on-site potential disorder and coupling emerging through the inter-chain hopping $t'$, is analysed. The study is motivated by the experiment ... More
The generalized Catalan equation in positive characteristicOct 20 2016Let $K = \mathbb{F}_p(z_1, \ldots, z_r)$ be a finitely generated field over $\mathbb{F}_p$. In this article we study the generalized Catalan equation $ax^m + by^n = 1$ in $x, y \in K$ and integers $m, n > 1$ coprime with $p$. Our main result shows that ... More
Plasticity-rigidity cycles: A general adaptation mechanismNov 04 2015Nov 06 2015Successful adaptation helped the emergence of complexity. Alternating plastic- and rigid-like states were recurrently considered to play a role in adaptive processes. However, this extensive knowledge remained fragmented. In this paper I describe plasticity-rigidity ... More
Elementary construction of Lusztig's canonical basisFeb 16 2016Jun 06 2016In this largely expository article we present an elementary construction of Lusztig's canonical basis in type ADE. The method, which is essentially Lusztig's original approach, is to use the braid group to reduce to rank two calculations. Some of the ... More
Quantum circuits of T-depth oneOct 03 2012Apr 03 2013We give a Clifford+T representation of the Toffoli gate of T-depth 1, using four ancillas. More generally, we describe a class of circuits whose T-depth can be reduced to 1 by using sufficiently many ancillas. We show that the cost of adding an additional ... More
Generators and relations for n-qubit Clifford operatorsOct 25 2013Jun 18 2015We define a normal form for Clifford circuits, and we prove that every Clifford operator has a unique normal form. Moreover, we present a rewrite system by which any Clifford circuit can be reduced to normal form. This yields a presentation of Clifford ... More
Killip-Simon problem and Jacobi flow on GMP matricesMay 05 2015One of the first theorems in perturbation theory claims that for an arbitrary self-adjoint operator A there exists a perturbation B of Hilbert-Schmidt class, which destroys completely the absolutely continuous spectrum of A (von Neumann). However, if ... More
The Length Scales of Dynamic Heterogeneity: Results from Molecular Dynamics SimulationsSep 29 2010Over times shorter than that required for relaxation of enthalpy, a liquid can exhibit striking heterogeneities. The picture of these heterogeneities is complex with transient patches of rigidity, irregular yet persistent, intersected by tendrils of mobile ... More
Cross-intersecting integer sequencesDec 31 2012Jan 17 2014We call $(a_1, \dots, a_n)$ an \emph{$r$-partial sequence} if exactly $r$ of its entries are positive integers and the rest are all zero. For ${\bf c} = (c_1, \dots, c_n)$ with $1 \leq c_1 \leq \dots \leq c_n$, let $S_{\bf c}^{(r)}$ be the set of $r$-partial ... More
Electronic transport in strongly anisotropic disordered systems: model for the random matrix theory with non-integer betaSep 17 2000Jan 18 2002We study numerically an electronic transport in strongly anisotropic weakly disorderd two-dimensional systems. We find that the conductance distribution is gaussian but the conductance fluctuations increase when anisotropy becomes stronger. We interpret ... More
Correction to the 2005 paper: "Digit Selection for SRT Division and Square Root"Nov 24 2014It has been pointed out by counterexamples in a 2013 paper in the IEEE Transactions on Computers [1], that there is an error in the previously ibid.\ in 2005 published paper [2] on the construction of valid digit selection tables for SRT type division ... More
A Review of the Instability of Hot Electroweak Theory and its Bounds on $m_h$ and $m_t$Dec 22 1992[Talk presented at the International Seminar Quarks `92, Zvenigorod, Russia, May 11-17, 1992.] The electroweak vacuum need not be absolutely stable. For certain top and Higgs masses in the Minimal Standard Model, it is instead metastable with a lifetime ... More
An Overview of the $ε$ Expansion and the Electroweak Phase TransitionJul 18 1994Talk presented at the NATO Advanced Workshop on Electroweak Physics and the Early Universe: Sintra, Portugal, 1994. I summarize work done with Larry Yaffe on applying $\epsilon$ expansion techniques to the electroweak phase transition.
Energy Spectrum of Quasi-Geostrophic TurbulenceJul 24 2002We consider the energy spectrum of a quasi-geostrophic model of forced, rotating turbulent flow. We provide a rigorous a priori bound E(k) <= Ck^{-2} valid for wave numbers that are smaller than a wave number associated to the forcing injection scale. ... More
Versal embeddings of compact, regular 3-pseudoconcave CR submanifoldsSep 24 2001We prove that for an induced CR structure on a compact, generic, regular 3-pseudoconcave CR submanifold ${\bold M}\subset{\bold G}$, of a complex manifold ${\bold G}$, satisfying condition $\dim H^1({\bold M}, T^{\prime}({\bold G})|_{\bold M})=0$ all ... More
A note on pseudo-Anosov maps with small growth rateSep 25 2003We present an explicit sequence of pseudo-Anosov maps $\phi_k: S_{2k}\to S_{2k}$ of surfaces of genus $2k$ whose growth rates converge to one.
Morita base change in quantum groupoidsApr 29 2002Let $L$ be a quantum semigroupoid, more precisely a $\times_R$-bialgebra in the sense of Takeuchi. We describe a procedure replacing the algebra $R$ by any Morita equivalent, or in fact more generally any $\sqrt{\text{Morita}}$ equivalent (in the sense ... More
Spin Correlations in Monte Carlo SimulationsOct 08 2001We show that the algorithm originally proposed by Collins and Knowles for spin correlations in the QCD parton shower can be used in order to include spin correlations between the production and decay of heavy particles in Monte Carlo event generators. ... More
Maximizing the spin correlation of top quark pairs produced at the LHCDec 07 2004The measurement of top quark spin correlation is an important tool for precise studies of top quark interactions. In this letter I construct a quantization axis maximizing the spin correlation at the LHC within the Standard Model. Using this axis a spin ... More
Signal transport in and conductance of correlated nanostructuresJul 16 2013Here we report on our project concerning the application of time dependent DMRG to strongly correlated systems. We show that a previously reported simulation of the spin charge separation in a one-dimensional Hubbard system exceeds a relative error of ... More
The dark side of DFT based transport calculationsFeb 13 2013We compare the conductance of an interacting ring of six lattice sites threaded by flux $\pi$ in a two terminal setup with the conductance of the corresponding Kohn-Sham particles. Based on symmetry considerations we can show that even within (lattice) ... More
Calculating Green Functions from Finite SystemsJan 15 2010In calculating Green functions for interacting quantum systems numerically one often has to resort to finite systems which introduces a finite size level spacing. In order to describe the limit of system size going to infinity correctly, one has to introduce ... More
Photon-induced Reactions in Stars and in the Laboratory: A Critical ComparisonMay 28 2004Photon-induced reactions during the astrophysical p- (or gamma-) process occur at typical temperatures of 1.8 < T9 < 3.3. Experimental data of (gamma,n), (gamma,p), or (gamma,alpha) reactions - if available in the relevant energy region - cannot be used ... More
Unexpected properties of the $^{33}$S($α$,p)$^{36}$Cl reaction cross section at low energiesApr 24 2014Apr 26 2014New experimental data for the $^{33}$S($\alpha$,p)$^{36}$Cl reaction show a very unusual energy dependence. Contrary to common findings for many other $\alpha$-induced reactions, statistical model calculations underestimate the measured cross sections ... More
Total reaction cross section $σ_{\rm{reac}}$ of $α$-induced reactions from elastic scattering: the example $^{140}$Ce($α$,$α$)$^{140}$CeMar 06 2013Angular distributions of elastic $^{140}$Ce($\alpha$,$\alpha$)$^{140}$Ce scattering are analyzed in the framework of the optical model from low energies around the Coulomb barrier up to about 40\,MeV. From the local fits the total reaction cross section ... More
Central hadron production in crossing of dedicated hadronic beamsMay 04 2004The original aim of this work, was to give a {\it brief} review of gluonic mesons, to be searched for in an experiment dedicated to central production of a relatively low mass hadronic system, whereby rapidity gaps are possible to impose, requiring initial ... More
Mass Generation in QCD -- Oscillating Quarks and GluonsApr 20 2014The present lecture is devoted to embedding the approximate genuine harmonic oscillator structure of valence q qbar mesons and in more detail the q q q configurations for up,down,strange - flavored baryons in Q C D for three light flavors of quark.
A quantum of historySep 21 2014With reference to primary sources it is shown that key claims made regarding the history of the pilot wave theory in Quantum Theory at the Crossroads are not supported by the historical record. It is also argued that the association of de Broglie with ... More
Spin-like current from phase space distributionsJan 04 2009The spin 0 generalized phase space approach provides a general expression for local current which depends on the choice of distribution function and generally deviates from the Schrodinger current. It is shown that the continuity equation restricts the ... More
What's wrong with Einstein's 1927 hidden-variable interpretation of quantum mechanics?Jan 05 2004Einstein's unpublished 1927 deterministic trajectory interpretation of quantum mechanics is critically examined, in particular with regard to the reason given by Einstein for rejecting his theory. It is shown that the aspect Einstein found objectionable ... More
Uniqueness of conserved currents in quantum mechanicsMay 29 2003It is proved by a functional method that the conventional expression for the Dirac current is the only conserved 4-vector implied by the Dirac equation that is a function of just the quantum state. The demonstration is extended to derive the unique conserved ... More
Quantum potential energy as concealed motionOct 01 2014Nov 13 2014It is known that the Schroedinger equation may be derived from a hydrodynamic model in which the Lagrangian position coordinates of a continuum of particles represent the quantum state. Using Routh\s method of ignorable coordinates it is shown that the ... More
The roads not taken: empty waves, wavefunction collapse and protective measurement in quantum theorySep 19 2014Within the class of ontological interpretations of quantum theory where a physical system comprises a particle and a field (wavefunction) guiding it, an empty wave is a segment of the wavefunction not containing the particle. We examine the impact of ... More
Hydrodynamics, particle relabelling and relativityMay 18 2011Using the wave equation as an example, it is shown how to extend the hydrodynamic Lagrangian-picture method of constructing field evolution using a continuum of trajectories to second-order theories. The wave equation is represented through Eulerian-picture ... More
Schrodinger dynamics as a two-phase conserved flow: an alternative trajectory construction of quantum propagationJul 28 2008Dec 16 2008It is shown that the Schrodinger equation can be cast in the form of two coupled real conservation equations, in Euclidean spacetime in the free case and in a five-dimensional Eisenhart geometry in the presence of an external potential. This implies a ... More
An estimate about multiple stochastic integrals with respect to a normalized empirical measureOct 20 2003Let a sequence of iid. random variables $\xi_1,...,\xi_n$ be given on a measurable space $(X,\cal X)$ with distribution $\mu$ together with a function $f(x_1,...,x_k)$ on the product space $(X^k,{\cal X}^k)$. Let $\mu_n$ denote the empirical measure defined ... More