Results for "Ole Martin Brokstad"

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Towards autonomous ocean observing systems using Miniature Underwater Gliders with UAV deployment and recovery capabilitiesFeb 08 2019This paper presents preliminary results towards the development of an autonomous ocean observing system using Miniature Underwater Gliders (MUGs) that can operate with the support of Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vessels (USVs) ... More
Optimal leverage from non-ergodicityFeb 17 2009Aug 09 2010In modern portfolio theory, the balancing of expected returns on investments against uncertainties in those returns is aided by the use of utility functions. The Kelly criterion offers another approach, rooted in information theory, that always implies ... More
Menger 1934 revisitedOct 07 2011Karl Menger's 1934 paper on the St. Petersburg paradox contains mathematical errors that invalidate his conclusion that unbounded utility functions, specifically Bernoulli's logarithmic utility, fail to resolve modified versions of the St. Petersburg ... More
Galaxy cluster strong lensing: image deflections from density fluctuations along the line of sightOct 24 2011Dec 08 2011A standard method to study the mass distribution in galaxy clusters is through strong lensing of background galaxies in which the positions of multiple images of the same source constrain the surface mass distribution of the cluster. However, current ... More
The lattice thermal conductivity of Ti$_x$Zr$_y$Hf$_{1-x-y}$NiSn half-Heusler alloys calculated from first principles: Key role of phonon mode natureNov 06 2016In spite of their relatively high lattice thermal conductivity $\kappa_{\ell}$, the XNiSn (X=Ti, Zr or Hf) half-Heusler compounds are good thermoelectric materials. Previous studies have shown that $\kappa_{\ell}$ can be reduced by sublattice-alloying ... More
Predictive Active Set Selection Methods for Gaussian ProcessesFeb 22 2011Jun 23 2011We propose an active set selection framework for Gaussian process classification for cases when the dataset is large enough to render its inference prohibitive. Our scheme consists of a two step alternating procedure of active set update rules and hyperparameter ... More
Highly sensitive refractometer with photonic crystal fiber long-period gratingNov 19 2007We present highly sensitive refractometers based on a long-period grating in a large mode area PCF. The maximum sensitivity is 1500 nm/RIU at a refractive index of 1.33, the highest reported for any fiber grating. The minimal detectable index change is ... More
Quantum speed limits and optimal Hamiltonians for driven systems in mixed statesDec 21 2013Apr 28 2014Inequalities of Mandelstam-Tamm and Margolus-Levitin type provide lower bounds on the time it takes for a quantum system to evolve from one state into another. Knowledge of such bounds, called quantum speed limits, is of utmost importance in virtually ... More
Ergodicity breaking in geometric Brownian motionSep 20 2012Mar 14 2013Geometric Brownian motion (GBM) is a model for systems as varied as financial instruments and populations. The statistical properties of GBM are complicated by non-ergodicity, which can lead to ensemble averages exhibiting exponential growth while any ... More
Remarks on the paper "Skew Pieri rules for Hall-Littlewood functions" by Konvalinka and LauveAug 20 2012In a recent paper Konvalinka and Lauve proved several skew Pieri rules for Hall-Littlewood polynomials. In this note we show that q-analogues of these rules are encoded in a q-binomial theorem for Macdonald polynomials due to Lascoux and the author.
Self-organized Criticality and Absorbing States: Lessons from the Ising ModelNov 29 2004We investigate a suggested path to self-organized criticality. Originally, this path was devised to "generate criticality" in systems displaying an absorbing-state phase transition, but closer examination of the mechanism reveals that it can be used for ... More
Boron-doping of cubic SiC for intermediate band solar cells: a scanning transmission electron microscopy studyApr 18 2018Dec 10 2018Boron (B) has the potential for generating an intermediate band in cubic silicon carbide (3C-SiC), turning this material into a highly efficient absorber for single-junction solar cells. The formation of a delocalized band demands high concentration of ... More
Solitons in coupled atomic-molecular Bose-Einstein condensates in a trapMay 16 2006Mar 26 2008We consider coupled atomic-molecular Bose-Einstein condensate system in a quasi-one-dimensional trap. In the vicinity of a Feshbach resonance the system can reveal soliton-like behavior. We analyze bright soliton solutions for the system in the trap and ... More
Low-bandwidth and non-compute intensive remote identification of microbes from raw sequencing readsJun 06 2013Jun 21 2013Cheap high-throughput DNA sequencing may soon become routine not only for human genomes but also for practically anything requiring the identification of living organisms from their DNA: tracking of infectious agents, control of food products, bioreactors, ... More
Stochastic Market EfficiencyJan 24 2011It is argued that the simple trading strategy of leveraging or deleveraging an investment in the market portfolio cannot outperform the market. Such stochastic market efficiency places strong constraints on the possible stochastic properties of the market. ... More
The A_{2n}^{(2)} Rogers-Ramanujan identitiesSep 20 2013Nov 05 2013The famous Rogers-Ramanujan and Andrews--Gordon identities are embedded in a doubly-infinite family of Rogers-Ramanujan-type identities labelled by positive integers m and n. For fixed m and n the product side corresponds to a specialised character of ... More
Origin of the Orbital Ordering in LaMnO$_3$Mar 12 2003We use the temperature of the structural phase transition to determine the Jahn-Teller (JT) coupling constant in the model derived for LaMnO$_3$ which includes both the superexchange between S=2 spins and the JT effect. We also investigate the dependence ... More
CPDY: Extending the Dolev-Yao Attacker with Physical-Layer InteractionsJul 09 2016Jul 20 2016We propose extensions to the Dolev-Yao attacker model to make it suitable for arguments about security of Cyber-Physical Systems. The Dolev-Yao attacker model uses a set of rules to define potential actions by an attacker with respect to messages (i.e. ... More
Modular Nekrasov-Okounkov formulasFeb 09 2019Using Littlewood's map, which decomposes a partition into its $r$-core and $r$-quotient, Han and Ji have shown that many well-known hook-length formulas admit modular analogues. In this paper we present a variant of the Han-Ji `multiplication theorem' ... More
Laws of large numbers for Hayashi-Yoshida-type functionalsMar 15 2018In high-frequency statistics and econometrics sums of functionals of increments of stochastic processes are commonly used and statistical inference is based on the asymptotic behaviour of these sums as the mesh of the observation times tends to zero. ... More
Testing for simultaneous jumps in case of asynchronous observationsJun 23 2016This paper proposes a novel test for simultaneous jumps in a bivariate It\^o semimartingale when observation times are asynchronous and irregular. Inference is built on a realized correlation coefficient for the jumps of the two processes which is estimated ... More
Protein Secondary Structure Prediction with Long Short Term Memory NetworksDec 25 2014Jan 04 2015Prediction of protein secondary structure from the amino acid sequence is a classical bioinformatics problem. Common methods use feed forward neural networks or SVMs combined with a sliding window, as these models does not naturally handle sequential ... More
Jahn-Teller Effect and Superexchange in Half-Doped ManganitesMar 12 2003We investigate the stability of the charge exchange (CE) phase within a microscopic model which describes a single plane as in La$_{0.5}$Sr$_{1.5}$MnO$_4$. The model includes Coulomb interactions (on-site and intersite), the Jahn-Teller term and the superexchange ... More
Inverse scattering in multimode structuresJul 22 2007We consider the inverse scattering problem associated with any number of interacting modes in one-dimensional structures. The coupling between the modes is contradirectional in addition to codirectional, and may be distributed continuously or in discrete ... More
Conjugate Bailey pairsJun 14 1999In this paper it is shown that the one-dimensional configuration sums of the solvable lattice models of Andrews, Baxter and Forrester and the string functions associated with admissible representations of the affine Lie algebra A$_1^{(1)}$ as introduced ... More
Accurate gradient computations for shape optimization via discrete adjoints in CFD-related multiphysics problemsOct 31 2018As more and more multiphysics effects are entering the field of CFD simulations, this raises the question how they can be accurately captured in gradient computations for shape optimization. The latter has been successfully enriched over the last years ... More
Attend, Copy, Parse - End-to-end information extraction from documentsDec 18 2018Document information extraction tasks performed by humans create data consisting of a PDF or document image input, and extracted string outputs. This end-to-end data is naturally consumed and produced when performing the task because it is valuable in ... More
An Adaptive Resample-Move Algorithm for Estimating Normalizing ConstantsApr 07 2016Aug 15 2016The estimation of normalizing constants is a fundamental step in probabilistic model comparison. Sequential Monte Carlo methods may be used for this task and have the advantage of being inherently parallelizable. However, the standard choice of using ... More
Interplay of orbitally polarized and magnetically ordered phases in doped transition metal oxidesFeb 06 2005We investigate the magnetic instabilities of the two-dimensional model of interacting e_g electrons for hole doping away from two electrons per site in the mean-field approximation. In particular, we address the occurrence of orbitally polarized states ... More
New Directions for Trust in the Certificate Authority EcosystemJan 03 2018Many of the benefits we derive from the Internet require trust in the authenticity of HTTPS connections. Unfortunately, the public key certification ecosystem that underwrites this trust has failed us on numerous occasions. Towards an exploration of the ... More
Relative and center-of-mass motion in the attractive Bose-Hubbard modelFeb 16 2012Mar 22 2012We present first-principle numerical calculations for few particle solutions of the attractive Bose-Hubbard model with periodic boundary conditions. We show that the low-energy many-body states found by numerical diagonalization can be written as translational ... More
Bounded Littlewood identitiesJun 09 2015Feb 19 2018We describe a method, based on the theory of Macdonald-Koornwinder polynomials, for proving bounded Littlewood identities. Our approach provides an alternative to Macdonald's partial fraction technique and results in the first examples of bounded Littlewood ... More
A Theory of Solving TAP Equations for Ising Models with General Invariant Random MatricesSep 03 2015Mar 28 2016We consider the problem of solving TAP mean field equations by iteration for Ising model with coupling matrices that are drawn at random from general invariant ensembles. We develop an analysis of iterative algorithms using a dynamical functional approach ... More
Perturbative Corrections for Approximate Inference in Gaussian Latent Variable ModelsJan 12 2013Oct 25 2013Expectation Propagation (EP) provides a framework for approximate inference. When the model under consideration is over a latent Gaussian field, with the approximation being Gaussian, we show how these approximations can systematically be corrected. A ... More
Spherical collapse of dark energy with an arbitrary sound speedAug 31 2010Apr 27 2012We consider a generic type of dark energy fluid, characterised by a constant equation of state parameter w and sound speed c_s, and investigate the impact of dark energy clustering on cosmic structure formation using the spherical collapse model. Along ... More
Ensemble Toolkit: Scalable and Flexible Execution of Ensembles of TasksFeb 01 2016Jun 27 2016There are many science applications that require scalable task-level parallelism and support for flexible execution and coupling of ensembles of simulations. Most high-performance system software and middleware, however, are designed to support the execution ... More
Dynamical Functional Theory for Compressed SensingMay 11 2017We introduce a theoretical approach for designing generalizations of the approximate message passing (AMP) algorithm for compressed sensing which are valid for large observation matrices that are drawn from an invariant random matrix ensemble. By design, ... More
Self-Averaging Expectation PropagationAug 23 2016We investigate the problem of approximate Bayesian inference for a general class of observation models by means of the expectation propagation (EP) framework for large systems under some statistical assumptions. Our approach tries to overcome the numerical ... More
Analysis of the Diffuse Domain Method for second order elliptic boundary value problemsDec 17 2014The diffuse domain method for partial differential equations on complicated geometries recently received strong attention in particular from practitioners, but many fundamental issues in the analysis are still widely open. In this paper we study the diffuse ... More
Direct subsurface absorption of hydrogen on Pd(111)Dec 13 1995We summarize and discuss some of the available experimental and theoretical data important for understanding the role played by subsurface sites in dissociative chemisorption calculations for the H$_2$/Pd(111) system. Then we use a semi-empirical potential ... More
Diffuse Interface Methods for Inverse Problems: Case Study for an Elliptic Cauchy ProblemJun 18 2015Jul 10 2015Many inverse problems have to deal with complex, evolving and often not exactly known geometries, e.g. as domains of forward problems modeled by partial differential equations. This makes it desirable to use methods which are robust with respect to perturbed ... More
On Gabor frames generated by sign-changing windows and B-splinesMar 07 2015For a class of compactly supported windows we characterize the frame property for a Gabor system $\mts,$ for translation parameters $a$ belonging to a certain range depending on the support size. We show that the obstructions to the frame property are ... More
On extensions of wavelet systems to dual pairs of framesJan 05 2014It is an open problem whether any pair of Bessel sequences with wavelet structure can be extended to a pair of dual frames by adding a pair of singly generated wavelet systems. We consider the particular case where the given wavelet systems are generated ... More
Free Field Representations of Extended Superconformal AlgebrasJul 03 1992We study the classical and quantum $G$ extended superconformal algebras from the hamiltonian reduction of affine Lie superalgebras, with even subalgebras $G\oplus sl(2)$. At the classical level we obtain generic formulas for the Poisson bracket structure ... More
Generic features of modulational instability in nonlocal Kerr mediaMay 22 2001The modulational instability (MI) of plane waves in nonlocal Kerr media is studied for a general, localized, response function. It is shown that there always exists a finite number of well-separated MI gain bands, with each of them characterised by a ... More
End-to-End Information Extraction without Token-Level SupervisionJul 16 2017Most state-of-the-art information extraction approaches rely on token-level labels to find the areas of interest in text. Unfortunately, these labels are time-consuming and costly to create, and consequently, not available for many real-life IE tasks. ... More
Avalanche Behavior in an Absorbing State Oslo ModelMay 19 2004Jul 15 2004Self-organized criticality can be translated into the language of absorbing state phase transitions. Most models for which this analogy is established have been investigated for their absorbing state characteristics. In this article, we transform the ... More
Escape angles in bulk chi(2) soliton interactionsOct 16 2000Nov 06 2001We develop a theory for non-planar interaction between two identical type I spatial solitons propagating at opposite, but arbitrary transverse angles in quadratic nonlinear (or so-called chi(2)) bulk media. We predict quantitatively the outwards escape ... More
Convolutional LSTM Networks for Subcellular Localization of ProteinsMar 06 2015Machine learning is widely used to analyze biological sequence data. Non-sequential models such as SVMs or feed-forward neural networks are often used although they have no natural way of handling sequences of varying length. Recurrent neural networks ... More
Sequential Neural Models with Stochastic LayersMay 24 2016Nov 13 2016How can we efficiently propagate uncertainty in a latent state representation with recurrent neural networks? This paper introduces stochastic recurrent neural networks which glue a deterministic recurrent neural network and a state space model together ... More
Toric Construction of Global F-Theory GUTsJan 25 2011Feb 28 2011We systematically construct a large number of compact Calabi-Yau fourfolds which are suitable for F-theory model building. These elliptically fibered Calabi-Yaus are complete intersections of two hypersurfaces in a six dimensional ambient space. We first ... More
Logarithmic and complex constant term identitiesDec 14 2011Mar 04 2012In recent work on the representation theory of vertex algebras related to the Virasoro minimal models M(2,p), Adamovic and Milas discovered logarithmic analogues of (special cases of) the famous Dyson and Morris constant term identities. In this paper ... More
Domain walls that do not get stuck on impuritiesFeb 19 2019We present a field theoretical model which allows for domain walls that do not get stuck on impurities. For this purpose, we consider a generalized chiral magnet domain wall action with an impurity which couples both to a potential term as well as to ... More
A framework of Rogers-Ramanujan identities and their arithmetic propertiesJan 30 2014Jun 30 2016The two Rogers-Ramanujan $q$-series \[ \sum_{n=0}^{\infty}\frac{q^{n(n+\sigma)}}{(1-q)\cdots (1-q^n)}, \] where $\sigma=0,1$, play many roles in mathematics and physics. By the Rogers-Ramanujan identities, they are essentially modular functions. Their ... More
Theoretical analysis of oxygen vacancies in layered sodium cobaltate Na_xCoO_{2-δ}Nov 24 2011Nov 05 2012Sodium cobaltate with high Na content is a promising thermoelectric material. It has recently been reported that oxygen vacancies can alter the material properties, reducing its figure of merit. However, experimental data concerning the oxygen stoichiometry ... More
Dark energy properties from large future galaxy surveysApr 08 2013Apr 29 2014We perform a detailed forecast on how well a {\sc Euclid}-like survey will be able to constrain dark energy and neutrino parameters from a combination of its cosmic shear power spectrum, galaxy power spectrum, and cluster mass function measurements. We ... More
Confronting the sound speed of dark energy with future cluster surveysMay 02 2012Future cluster surveys will observe galaxy clusters numbering in the hundred thousands. We consider this work how these surveys can be used to constrain dark energy parameters: in particular, the equation of state parameter w and the non-adiabatic sound ... More
Gutzwiller theory of band magnetism in LaOFeAsSep 05 2011We use the Gutzwiller variational theory to calculate the ground-state phase diagram and quasi-particle bands of LaOFeAs. The Fe3d--As4p Wannier-orbital basis obtained from density-functional theory defines the band part of our eight-band Hubbard model. ... More
Amplitude noise and coherence degradation of femtosecond supercontinuum generation in all-normal-dispersion fibersFeb 04 2019Supercontinuum (SC) generation via femtosecond (fs) pumping in all-normal-dispersion (ANDi) fiber is predicted to offer completely coherent broadening mechanisms, potentially allowing for substantially reduced noise levels in comparison to those obtained ... More
Quasiperiodic Envelope SolitonsJul 26 1999We analyse nonlinear wave propagation and cascaded self-focusing due to second-harmonic generation in Fibbonacci optical superlattices and introduce a novel concept of nonlinear physics, the quasiperiodic soliton, which describes spatially localized self-trapping ... More
Molten o-H3PO4 - A New Electrolyte for the Anodic Synthesis of Self-Organized Oxide Structures: WO3 Nanochannel Layers and OthersOct 17 2016We introduce the use of pure molten ortho-phosphoric acid (o-H3PO4) as an electrolyte for selforganizing electrochemistry. This electrolyte allows for the formation of self-organized oxide architectures (one-dimensional nanotubes, nanochannels, nanopores) ... More
Influence of isolated and clustered defects on electronic and dielectric properties of wustiteJan 20 2015The influence of intrinsic Fe defects in FeO (either single cation vacancies or prototypical 4:1 vacancy clusters) on the electronic and dielectric properties is studied within the density functional theory. The importance of local Coulomb interactions ... More
Machine Learning for Novel Thermal-Materials Discovery: Early Successes, Opportunities, and ChallengesJan 17 2019High-throughput computational and experimental design of materials aided by machine learning have become an increasingly important field in material science. This area of research has emerged in leaps and bounds in the thermal sciences, in part due to ... More
Stable rotating dipole solitons in nonlocal optical mediaDec 20 2005We reveal that nonlocality can provide a simple physical mechanism for stabilization of multi-hump optical solitons, and present the first example of stable rotating dipole solitons and soliton spiraling, known to be unstable in all types of realistic ... More
Two-Stage Transfer Learning for Heterogeneous Robot Detection and 3D Joint Position Estimation in a 2D Camera Image using CNNFeb 15 2019Collaborative robots are becoming more common on factory floors as well as regular environments, however, their safety still is not a fully solved issue. Collision detection does not always perform as expected and collision avoidance is still an active ... More
Full-field hard x-ray microscopy with interdigitated silicon lensesJun 22 2015Full-field x-ray microscopy using x-ray objectives has become a mainstay of the biological and materials sciences. However, the inefficiency of existing objectives at x-ray energies above 15 keV has limited the technique to weakly absorbing or two-dimensional ... More
Pebble Games and Linear EquationsApr 09 2012Mar 24 2015We give a new, simplified and detailed account of the correspondence between levels of the Sherali-Adams relaxation of graph isomorphism and levels of pebble-game equivalence with counting (higher-dimensional Weisfeiler-Lehman colour refinement). The ... More
Modern Regularization Methods for Inverse ProblemsJan 30 2018Regularization methods are a key tool in the solution of inverse problems. They are used to introduce prior knowledge and make the approximation of ill-posed (pseudo-)inverses feasible. In the last two decades interest has shifted from linear towards ... More
Debian Astro: An open computing platform for astronomyNov 22 2016Debian Astro is a Debian Pure Blend that aims to distribute the available astronomy software within the Debian operating system. Using Debian as the foundation has unique advantages for end-users and developers such as an easy installation and upgrading ... More
Status of the vertex detector program of the CBM experiment at FAIROct 19 2018The Compressed Baryonic Matter Experiment (CBM) is one of the core experiments of the future FAIR facility (Darmstadt/Germany). The fixed-target experiment will explore the phase diagram of strongly interacting matter in the regime of high net baryon ... More
Photo-acoustic sensor for detection of oil contamination in compressed air systemsDec 13 2016We demonstrate an online (in-situ) sensor for continuous detection of oil contamination in compressed air systems complying with the ISO-8573 standard. The sensor is based on the photo-acoustic (PA) effect. The online and real-time PA sensor system has ... More
Solving systems of linear equations on a quantum computerFeb 05 2013Systems of linear equations are used to model a wide array of problems in all fields of science and engineering. Recently, it has been shown that quantum computers could solve linear systems exponentially faster than classical computers, making for one ... More
A New Riemannian Setting for Surface RegistrationJun 03 2011Sep 19 2014We present a new approach for matching regular surfaces in a Riemannian setting. We use a Sobolev type metric on deformation vector fields which form the tangent bundle to the space of surfaces. In this article we compare our approach with the diffeomorphic ... More
A tight bound on the speed-up through storage for quickest multi-commodity flowsJun 18 2014Multi-commodity flows over time exhibit the non-intuitive property that letting flow wait can allow us to send flow faster overall. Fleischer and Skutella (IPCO~2002) show that the speed-up through storage is at most a factor of~$2$, and that there are ... More
On the representation of polyhedra by polynomial inequalitiesMar 26 2002Oct 24 2002A beautiful result of Br\"ocker and Scheiderer on the stability index of basic closed semi-algebraic sets implies, as a very special case, that every $d$-dimensional polyhedron admits a representation as the set of solutions of at most $d(d+1)/2$ polynomial ... More
Optimal Partitioning for Dual-Pivot QuicksortMar 21 2013Oct 13 2015Dual-pivot quicksort refers to variants of classical quicksort where in the partitioning step two pivots are used to split the input into three segments. This can be done in different ways, giving rise to different algorithms. Recently, a dual-pivot algorithm ... More
Neutralino Dark Matter and the CurvatonNov 30 2006Mar 09 2007We build a realistic model of curvaton cosmology, in which the energy content is described by radiation, WIMP dark matter and a curvaton component. We calculate the curvature and isocurvature perturbations, allowing for arbitrary initial density perturbations ... More
Algorithmic Optimisations for Iterative Deconvolution MethodsApr 26 2013We investigate possibilities to speed up iterative algorithms for non-blind image deconvolution. We focus on algorithms in which convolution with the point-spread function to be deconvolved is used in each iteration, and aim at accelerating these convolution ... More
Enhancement of thermoelectric properties by energy filtering: Theoretical potential and experimental reality in nanostructured ZnSbMar 21 2016Energy filtering has been suggested by many authors as a means to improve thermoelectric properties. The idea is to filter away low-energy charge carriers in order to increase Seebeck coefficient without compromising electronic conductivity. This concept ... More
Self-Awareness of Cloud ApplicationsNov 01 2016Cloud applications today deliver an increasingly larger portion of the Information and Communication Technology (ICT) services. To address the scale, growth, and reliability of cloud applications, self-aware management and scheduling are becoming commonplace. ... More
Six problems in frame theoryAug 23 2013We discuss various problems in frame theory that have been open for some years. A short discussion of frame theory is also provided, but it only contains the information that is necessary in order to understand the open problems and their role.
Quasi-4-Connected ComponentsFeb 14 2016We introduce a new decomposition of a graphs into quasi-4-connected components, where we call a graph quasi-4-connected if it is 3-connected and it only has separations of order 3 that remove a single vertex. Moreover, we give a cubic time algorithm computing ... More
Sharp Bounds for Eigenvalues and Multiplicities on Surfaces of RevolutionApr 12 1996We find sharp upper bounds for the multiplicities and the numerical values of all the distinct eigenvalues on a surface of revolution diffeomorphic to the sphere.
Interplay of site and bond electron-phonon coupling in one dimensionOct 07 2016The interplay of bond and charge correlations is studied in a one-dimensional model with both Holstein and Su-Schrieffer-Heeger (SSH) couplings to quantum phonons. The problem is solved exactly by quantum Monte Carlo simulations. If one of the couplings ... More
A variance reduced estimator of the connected two-point function in the presence of a broken Z_2 symmetryDec 08 2015The exchange or geometric cluster algorithm allows us to define a variance reduced estimator of the connected two-point function in the presence of a broken Z_2-symmetry. We present first numerical tests for the improved Blume-Capel model on the simple ... More
Search for CP Violation in the Decay Z -> b (b bar) gAug 01 1996About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between ... More
M-branes on U-foldsDec 27 2007We give a preliminary discussion of how the addition of extra coordinates in M-theory, which together with the original ones parametrise a U-fold, can serve as a tool for formulating brane dynamics with manifest U-duality. The redundant degrees of freedom ... More
Superspace Methods in String Theory, Supergravity and Gauge TheoryMay 18 2001In these two lectures, delivered at the XXXVII Karpacz Winter School, February 2001, I review some applications of superspace in various topics related to string theory and M-theory. The first lecture is mainly devoted to descriptions of brane dynamics ... More
World-volume fields and background coupling of branesJun 18 1998This is the written version of an invited talk delivered at the workshop ``Quantum gravity in the Southern Cone'' held in San Carlos de Bariloche, Argentina, January 7-10, 1998. After giving a brief introduction to the concept of branes and their role ... More
Aspects of D-brane actionsDec 14 1996A couple of issues concerning the effective dynamics of D-branes in string theory are discussed. Primarily, I am concerned with linearization of the actions by introduction of non-propagating fields and a full super- and kappa-symmetric description of ... More
T-duality and non-geometric solutions from double geometrySep 15 2014Although the introduction of generalised and extended geometry has been motivated mainly by the appearance of dualities upon reductions on tori, it has until now been unclear how (all) the duality transformations arise from first principles in extended ... More
Thoughts on Membranes, Matrices and Non-CommutativityOct 11 2004We review the passage from the supermembrane to matrix theory via a consistent truncation following a non-commutative deformation in light-cone gauge. Some indications are given that there should exist a generalisation of non-commutativity involving a ... More
Confinement at Weak CouplingNov 03 2005The free energy of U(N) and SU(N) gauge theory was recently found to be of order N^0 to all orders of a perturbative expansion about a center-symmetric orbit of vanishing curvature. Here I consider extended models for which this expansion is perturbatively ... More
Mass Generation in Continuum SU(2) Gauge Theory in Covariant Abelian GaugesSep 02 1999Jan 17 2000The local action of an SU(2) gauge theory in general covariant Abelian gauges and the associated equivariant BRST symmetry that guarantees the perturbative renormalizability of the model are given. I show that a global SL(2,R) symmetry of the model is ... More
Quantization in the Presence of Gribov AmbiguitiesOct 21 1998The non-perturbative validity of covariant BRST-quantization of gauge theories on compact Euclidean space-time manifolds is reviewed. BRST-quantization is related to the construction of a Topological Quantum Field Theory (TQFT) of Witten type on the gauge ... More
Systematic Study of Hadronic Molecules in the Heavy-Quark SectorMay 16 2014In this work we study the properties of hadronic molecules in the heavy-quark sector. These have become increasingly important since from the beginning of this century a large number of states have been measured that for different reasons do not fit the ... More
Filtration shrinkage, strict local martingales and the Föllmer measureNov 30 2011May 19 2014When a strict local martingale is projected onto a subfiltration to which it is not adapted, the local martingale property may be lost, and the finite variation part of the projection may have singular paths. This phenomenon has consequences for arbitrage ... More
Spectrum and Quantum Symmetries of the ${\rm AdS}_5 \times {\rm S}^5$ SuperstringJul 10 2015The the duality between ${\cal N}=4$ SYM and the AdS$_5\times\;$S$^5$ superstring appears to enjoy quantum integrability in the planar limit, which allowed to devise powerful methods ostensibly solving the spectral problem. However, quantization of the ... More
Charge-Ordering Phenomena in One-Dimensional SolidsMay 13 2007As the dimensionality is reduced, the world becomes more and more interesting; novel and fascinating phenomena show up which call for understanding. Physics in one dimension is a fascinating topic for theory and experiment: for the former often a simplification, ... More
NNLO contributions to epsilon_K and rare kaon decaysSep 11 2009We discuss the theory prediction of epsilon_K and the rare K -> pi nu nu-bar decays and review the structure and current status of higher-order contributions to these flavour changing processes in the standard model in some detail. This includes the next-to-next-to-leading ... More