Results for "Fabian Böttcher"

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The low-energy Goldstone mode in a trapped dipolar supersolidJun 11 2019A supersolid is a counter-intuitive state of matter that combines the frictionless flow of a superfluid with the crystal-like periodic density modulation of a solid. Since the first prediction in the 1950s, experimental efforts to realize this state have ... More
Embedded Markov chain approximations in Skorokhod topologiesSep 16 2014Jan 30 2018In order to approximate a continuous time stochastic process by discrete time Markov chains one has several options to embed the Markov chains into continuous time processes. On the one hand there is the Markov embedding, which uses exponential waiting ... More
Feller Evolution Systems: Generators and ApproximationMay 02 2013A time and space inhomogeneous Markov process is a Feller evolution process, if the corresponding evolution system on the continuous functions vanishing at infinity is strongly continuous. We discuss generators of such systems and show that under mild ... More
Markovian Maximal Coupling of Markov ProcessesOct 26 2017Markovian maximal couplings of Markov processes are characterized by an equality of total variation and a distance of Wasserstein type. If a Markovian maximal coupling is a Feller process, the generator can be calculated, e.g. for reflection coupled Brownian ... More
Dependence and dependence structures: estimation and visualization using distance multivarianceDec 18 2017Feb 07 2019Distance multivariance is a multivariate dependence measure, which can detect dependencies between an arbitrary number of random vectors each of which can have a distinct dimension. Here we discuss several new aspects and present a concise overview. We ... More
Polarized Parton DensitiesDec 31 2002In this talk we summarize main results of a recent determination of the polarized deeply inelastic parton distributions to NLO from the world data. In the analysis the LO and NLO parton densities and their $1\sigma$ statistical errors were derived and ... More
The Euler scheme for Feller processesNov 27 2009Jun 30 2010We consider the Euler scheme for stochastic differential equations with jumps, whose intensity might be infinite and the jump structure may depend on the position. This general type of SDE is explicitly given for Feller processes and a general convergence ... More
Reverberation mapping of the central regions of active galactic nuclei using high-energy gamma-ray observationsApr 20 1995We calculate the time- and energy-dependent opacity of high-energy gamma-rays attenuated by pair production interaction with accretion-flare photons that are scattered by gas and dust surrounding thenuclei of active galaxies. We show that the temporal ... More
Onset of a modulational instability in trapped dipolar Bose-Einstein condensatesNov 20 2017Jan 23 2018We explore the phase diagram of a finite-sized dysprosium dipolar Bose-Einstein condensate in a cylindrical harmonic trap. We monitor the final state after the scattering length is lowered from the repulsive BEC regime to the quantum droplet regime. Either ... More
Striped states in a many-body system of tilted dipolesJun 28 2017Nov 28 2017We study theoretically and experimentally the behaviour of a strongly confined dipolar Bose-Einstein condensate, in the regime of quantum-mechanical stabilization by beyond-mean-field effects. Theoretically, we demonstrate that self-organized striped ... More
Transient supersolid properties in an array of dipolar quantum dropletsJan 23 2019Mar 08 2019We study theoretically and experimentally the emergence of supersolid properties in a dipolar Bose-Einstein condensate. The theory reveals a ground state phase diagram with three distinct regimes - a regular Bose-Einstein condensate, incoherent and coherent ... More
Anisotropic Superfluid Behavior of a Dipolar Bose-Einstein CondensateApr 12 2018Jul 18 2018We present transport measurements on a dipolar superfluid using a Bose-Einstein condensate of Dy-162 with strong magnetic dipole-dipole interactions. By moving an attractive laser beam through the condensate we observe an anisotropy in superfluid flow. ... More
Self-bound droplets of a dilute magnetic quantum liquidJul 25 2016Self-bound many-body systems occur in different scenarios all across the fields of physics. For example in the astrophysical context the stellar classification is based on a detailed balance of attractive self-gravitating forces and repulsive terms e.g. ... More
Transient supersolid properties in an array of dipolar quantum dropletsJan 23 2019We study theoretically and experimentally the emergence of supersolid properties in a dipolar Bose-Einstein condensate. The theory reveals a ground state phase diagram with three distinct regimes - a regular Bose-Einstein condensate, incoherent and coherent ... More
Self-bound droplets of a dilute magnetic quantum liquidJul 25 2016Nov 10 2016Self-bound many-body systems are formed through a balance of attractive and repulsive forces and occur in many physical scenarios. Liquid droplets are an example of a self-bound system, formed by a balance of the mutual attractive and repulsive forces ... More
Scissors mode of dipolar quantum droplets of dysprosium atomsDec 19 2017Mar 25 2018We report on the observation of the scissors mode of a single dipolar quantum droplet. The existence of this mode is due to the breaking of the rotational symmetry by the dipole-dipole interaction, which is fixed along an external homogeneous magnetic ... More
Almost spanning subgraphs of random graphs after adversarial edge removalMar 03 2010Apr 07 2013Let Delta>1 be a fixed integer. We show that the random graph G(n,p) with p>>(log n/n)^{1/Delta} is robust with respect to the containment of almost spanning bipartite graphs H with maximum degree Delta and sublinear bandwidth in the following sense: ... More
On the convergence rate of the three operator splitting schemeOct 25 2016The three operator splitting scheme was recently proposed by [Davis and Yin, 2015] as a method to optimize composite objective functions with one convex smooth term and two convex (possibly non-smooth) terms for which we have access to their proximity ... More
On the convergence rate of the three operator splitting schemeOct 25 2016Oct 29 2016The three operator splitting scheme was recently proposed by [Davis and Yin, 2015] as a method to optimize composite objective functions with one convex smooth term and two convex (possibly non-smooth) terms for which we have access to their proximity ... More
Asynchronous Distributed Automata: A Characterization of the Modal Mu-FragmentNov 25 2016Mar 06 2017We establish the equivalence between a class of asynchronous distributed automata and a small fragment of least fixpoint logic, when restricted to finite directed graphs. More specifically, the logic we consider is (a variant of) the fragment of the modal ... More
Topological order of mixed states in quantum many-body systemsSep 08 2016Jan 16 2017Topological order has become a new paradigm to distinguish ground states of interacting many-body systems without conventional long-range order. Here we discuss possible extensions of this concept to density matrices describing statistical ensembles. ... More
Distributed Automata and LogicMay 16 2018Distributed automata are finite-state machines that operate on finite directed graphs. Acting as synchronous distributed algorithms, they use their input graph as a network in which identical processors communicate for a possibly infinite number of synchronous ... More
Geodesic nets with three boundary verticesMar 10 2018Feb 21 2019We prove that a geodesic net with three boundary (= unbalanced) vertices on a non-positively curved plane has at most one balanced vertex. We do not assume any a priori bound for the degrees of unbalanced vertices. The result seems to be new even in the ... More
"I know it when I see it". Visualization and Intuitive InterpretabilityNov 20 2017Dec 06 2017Most research on the interpretability of machine learning systems focuses on the development of a more rigorous notion of interpretability. I suggest that a better understanding of the deficiencies of the intuitive notion of interpretability is needed ... More
Signal Formation Processes in Micromegas Detectors and Quality Control for large size Detector Construction for the ATLAS New Small WheelAug 04 2017Aug 09 2017The Micromegas technology is one of the most successful MPGD concepts and widely utilized in nuclear and particle physics experiments. Twenty years of research and development rendered the technology sufficiently mature to be selected as precision tracking ... More
Fully-coupled pressure-based algorithm for compressible flows: linearisation and iterative solution strategiesJul 11 2018The impact of different linearisation and iterative solution strategies for fully-coupled pressure-based algorithms for compressible flows at all speeds is studied, with the aim of elucidating their impact on the performance of the numerical algorithm. ... More
Theoretical Investigation of C_60 IR SpectrumFeb 16 1996Feb 19 1996A semi-empirical model of the infrared (IR) spectrum of the C$_{60}$ molecule is proposed. The weak IR-active modes seen experimentally in a C$_{60}$ crystalline sample are argued to be combination modes caused by anharmonicity. The origin of these 2-mode ... More
Almost every vector valued modular form is an oldformJan 23 2014Jan 27 2014In this article we show that 'most' of the vector valued modular forms w.r.t. the Weil representation on the groups rings $\mathbb{C}[D]$ of discriminant forms D are oldforms. The precise meaning of oldform is that the form can be represented as a sum ... More
Remarks on a quasi-linear model of the Navier-Stokes EquationsSep 19 2004Dinaburg and Sinai recently proposed a quasi-linear model of the Navier-Stokes equations. Their model assumes that nonlocal interactions in Fourier space are dominant, contrary to the Kolmogorov turbulence phenomenology where local interactions prevail. ... More
On an Exact and Nonparametric Test for the Separability of Two Classes by Means of a Simple ThresholdJul 14 2017This paper introduces a statistical test inferring whether a variable allows separating two classes by means of a single critical value. Its test statistic is the prediction error of a nonparametric threshold classifier. While this approach is adequate ... More
Algebraic Characters of Harish-Chandra Modules and ArithmeticityOct 25 2013These are expanded notes from lectures at the Workshop "Representation Theory and Applications" held at Yeditepe University, Istanbul, in honor of Roger E. Howe. They are supplemented by the application of algebraic character theory to the construction ... More
The pullback of a theta divisor to M_{g,n}Mar 14 2012Jan 07 2013We compute the class of a divisor on M_{g,n} given as the closure of the locus of smooth pointed curves [C; x_1,..., x_n] for which \sum d_j x_j has an effective representative, where d_j are integers summing up to g-1, not all positive. The techniques ... More
Moments of Spinor L-Functions and symplectic Kloosterman sumsMay 29 2018May 29 2019We compute the second moment of spinor $L$-functions at central points of Siegel modular forms on congruence subgroups of large prime level $N$ and give applications to non-vanishing.
Volume, Polar Volume and Euler Characteristic for Convex FunctionsJun 28 2018Functional analogs of the Euler characteristic and volume together with a new analog of the polar volume are characterized as non-negative, continuous, $\operatorname{SL}(n)$ and translation invariant valuations on the space of finite, convex and coercive ... More
Topological order of mixed states in quantum many-body systemsSep 08 2016Topological order has become a new paradigm to distinguish ground states of interacting many-body systems without conventional long-range order. Here we discuss possible extensions of this concept to density matrices describing statistical ensembles. ... More
Modulus of continuity of averages of SRB measures for a transversal family of piecewise expanding unimodal mapsApr 12 2016Let $f_t:[0,1] \to [0,1]$ be a family of piecewise expanding unimodal maps with a common critical point that is dense for almost all $t \in [a,b]$. If $\mu_t$ is the corresponding SRB measure for $f_t$, we study the regularity of $\Gamma(t)=\int \phi ... More
The effect of relative velocity and density perturbations between baryons and dark matter on the clustering of galaxiesFeb 29 2016Aug 24 2016Pre-recombination acoustic oscillations induce non-adiabatic perturbations between baryons and dark matter, corresponding to a constant relative-density $\delta_{bc}$ and decaying relative-velocity perturbation $\vec{v}_{bc}$. Due to their significant ... More
Towards a self-consistent halo model for the nonlinear large-scale structureNov 06 2015Feb 17 2016The halo model is a theoretically and empirically well-motivated framework for predicting the statistics of the nonlinear matter distribution in the Universe. However, current incarnations of the halo model suffer from two major deficiencies: $(i)$ they ... More
Polynomial Separating Algebras and Reflection GroupsJul 29 2013This note considers a finite algebraic group $G$ acting on an affine variety $X$ by automorphisms. Results of Dufresne on polynomial separating algebras for linear representations of $G$ are extended to this situation. For that purpose, we show that the ... More
Leafwise fixed points for $C^0$-small Hamiltonian flows and local coisotropic Floer homologyAug 20 2014Sep 10 2015Consider a closed coisotropic submanifold $N$ of a symplectic manifold $(M,\omega)$ and a Hamiltonian diffeomorphism $\phi$ on $M$. The main result of this article is that $\phi$ has a leafwise fixed point with respect to $N$, provided that it is the ... More
Hilbert-Samuel multiplicities of certain deformation ringsDec 20 2012Mar 31 2014We compute presentations of crystalline framed deformation rings of a two dimensional representation $\bar{\rho}$ of the absolute Galois group of $\mathbb{Q}_p$, when $\bar{\rho}$ has scalar semi-simplification, the Hodge-Tate weights are small and $p>2$. ... More
Distributed Graph AutomataApr 25 2014Inspired by distributed algorithms, we introduce a new class of finite graph automata that recognize precisely the graph languages definable in monadic second-order logic. For the cases of words and trees, it has been long known that the regular languages ... More
Weakly coupled N=4 Super Yang-Mills and N=6 Chern-Simons theories from u(2|2) Yangian symmetryOct 21 2008In this paper we derive the universal R-matrix for the Yangian Y(u(2|2)), which is an abstract algebraic object leading to rational solutions of the Yang-Baxter equation on representations. We find that on the fundamental representation the universal ... More
Monodromic Dark EnergySep 05 2017Oct 06 2017Since the discovery of the accelerated expansion of the Universe, the constraints on the equation of state $w_\text{DE}$ of dark energy, the stress-energy component responsible for the acceleration, have tightened significantly. These constraints generally ... More
Evolving neural networks with genetic algorithms to study the String LandscapeJun 21 2017Aug 10 2017We study possible applications of artificial neural networks to examine the string landscape. Since the field of application is rather versatile, we propose to dynamically evolve these networks via genetic algorithms. This means that we start from basic ... More
Recent progress in the partial-wave analysis of the diffractively produced $π^-π^+π^-$ final state at COMPASSAug 28 2018The COMPASS spectrometer at CERN has collected a large data set for diffractive three-pion production of $46\times10^6$ exclusive events. Based on previous conventional Partial-Wave Analyses (PWA), we performed a `freed-isobar PWA' on the same data, removing ... More
Improved tuning methods for Monte Carlo generatorsJan 22 2018The Monte Carlo event generators (MC) are used for the simulation of different processes in high energy physics. To achieve the best description of the data, the parameters of simulations are adjusted (tuned) with different methods. In this thesis extensions ... More
Separating Invariants of Finite GroupsApr 13 2017This paper studies separating invariants of finite groups acting on affine varieties through automorphisms. Several results, proved by Serre, Dufresne, Kac-Watanabe and Gordeev, and Jeffries and Dufresne exist that relate properties of the invariant ring ... More
Stable Frames in Model CategoriesFeb 15 2010We develop a stable analogue to the theory of cosimplicial frames in model cagegories; this is used to enrich all homotopy categories of stable model categories over the usual stable homotopy category and to give a different description of the smash product ... More
Valuations on Log-Concave FunctionsJul 20 2017A classification of $\operatorname{SL}(n)$ and translation covariant Minkowski valuations on log-concave functions is established. The moment vector and the recently introduced level set body of log-concave functions are characterized. Furthermore, analogs ... More
A remark on a relation between foliations and number theoryMay 07 2006We interpret a formula for meromorphic functions on foliations by Riemann surfaces as an analogue to the product formula of valuations in algebraic number theory.
Classification of Hamiltonian group actions on exact symplectic manifolds with proper momentum mapsJun 25 2018Jul 31 2018Let $G$ be a compact and connected Lie group. The $G$-model functor maps the category of symplectic representations of closed subgroups of $G$ to the category of exact Hamiltonian $G$-actions. Based on previous joint work with Y. Karshon, the restriction ... More
Non-Singlet QCD Analysis of the Structure Function F_2 in 3-LoopsJul 07 2004Jul 09 2004First results of a non--singlet QCD analysis of the structure function $F_2(x,Q^2)$ in 3--loop order based on the non--singlet world data are presented. Correlated errors are determined and their propagation through the evolution equations is performed ... More
Large-scale Velocities and Primordial Non-GaussianityMay 21 2010Jun 01 2010We study the peculiar velocities of density peaks in the presence of primordial non-Gaussianity. Rare, high density peaks in the initial density field can be identified with tracers such as galaxies and clusters in the evolved matter distribution. The ... More
Self-Consistent Cosmological Simulations of DGP Braneworld GravityMay 06 2009Sep 16 2009We perform cosmological N-body simulations of the Dvali-Gabadadze-Porrati braneworld model, by solving the full non-linear equations of motion for the scalar degree of freedom in this model, the brane bending mode. While coupling universally to matter, ... More
Dynamical Masses in Modified GravityMar 01 2010Mar 11 2010Differences in masses inferred from dynamics, such as velocity dispersions or X-rays, and those inferred from lensing are a generic prediction of modified gravity theories. Viable models however must include some non-linear mechanism to restore General ... More
Cosmological Simulations of Normal-Branch Braneworld GravityOct 01 2009Nov 30 2009We introduce a cosmological model based on the normal branch of DGP braneworld gravity with a smooth dark energy component on the brane. The expansion history in this model is identical to LambdaCDM, thus evading all geometric constraints on the DGP cross-over ... More
spikeSlabGAM: Bayesian Variable Selection, Model Choice and Regularization for Generalized Additive Mixed Models in RMay 26 2011The R package spikeSlabGAM implements Bayesian variable selection, model choice, and regularized estimation in (geo-)additive mixed models for Gaussian, binomial, and Poisson responses. Its purpose is to (1) choose an appropriate subset of potential covariates ... More
Dust in the Early (z>1) UniverseApr 01 2009Although dust emission at cosmological distances has only been detected a little more than a decade ago, remarkable progress has been achieved since then in characterizing the far-infrared emission of high-redshift systems. The mere fact that dust can ... More
On Period Relations for Automorphic L-functions IIApr 14 2016We study Hecke algebras for pairs (g,K) over arbitrary fields E of characteristic 0, define the Bernstein functor and give another definition of the Zuckerman functor over E. Building on this we show that hard duality remains valid over E and apply this ... More
A local proof of the Breuil-Mézard conjecture in the scalar semi-simplification caseJun 03 2015We give a new local proof of the Breuil-M\'ezard conjecture in the case of a reducible representation of the absolute Galois group of $\mathbb{Q}_p$, $p>2$, that has scalar semi-simplification, via a formalism of Pa\v{s}k\=unas.
Reverse Reconciliation Continuous Variable Quantum Key Distribution Based on the Uncertainty PrincipleMay 23 2014Nov 18 2014A big challenge in continuous variable quantum key distribution is to prove security against arbitrary coherent attacks including realistic assumptions such as finite-size effects. Recently, such a proof has been presented in [Phys. Rev. Lett. 109, 100502 ... More
First results from an extended freed-isobar analysis at COMPASSNov 29 2017One of the goals of the COMPASS experiment is the precision study of light-meson spectroscopy with data for various final states. With $46\times10^6$ exclusive events, the process $\pi^- p\to\pi^-\pi^+\pi^- p$ constitutes the flagship channel. Based on ... More
Non-abelian $p$-adic Rankin-Selberg $L$-functions and non-vanishing of central $L$-valuesAug 08 2017Oct 30 2018We prove new congruences between special values of Rankin-Selberg $L$-functions for $\mathrm{GL}(n+1)\times\mathrm{GL}(n)$ over arbitrary number fields. This allows us to control the behavior of $p$-adic $L$-functions under Tate twists and to prove the ... More
An example for a nontrivial irreducible geodesic net in the planeFeb 21 2019We construct a geodesic net in the plane with four unbalanced (boundary) vertices that has 16 balanced vertices and does not contain proper geodesic subnets. This is the first example of an irreducible geodesic net in the Euclidean plane with 4 boundary ... More
An extension of the Siegel space of complex abelian varieties and conjectures on stability structuresAug 20 2018We study semi--algebraic domains associated with symplectic tori and conjecturally identified with spaces of stability conditions on the Fukaya categories of these tori. Our motivation is to test which results from the theory of flat surfaces could hold ... More
On the convergence rate of the three operator splitting schemeOct 25 2016Dec 22 2016The three operator splitting scheme was recently proposed by [Davis and Yin, 2015] as a method to optimize composite objective functions with one convex smooth term and two convex (possibly non-smooth) terms for which we have access to their proximity ... More
Extraction of the $π^+π^-$ Subsystem in Diffractively Produced $π^-π^+π^-$ at COMPASSSep 27 2016The COMPASS experiment at CERN has collected a large data sample of 50 million diffractively produced $\pi^-\pi^+\pi^-$ events using a $190\,$GeV$/c$ negatively charged hadron beam. The partial-wave analysis (PWA) of these high-precision data reveals ... More
Hermitian Azumaya modules and arithmetic Chern classesJul 27 2016We compute arithmetic Chern classes of sheaves on an arithmetic surface X associated to a Hermitian Azumaya algebra.
Weak Lensing Probes of Modified GravityMay 30 2008Jul 14 2008We study the effect of modifications to General Relativity on large scale weak lensing observables. In particular, we consider three modified gravity scenarios: f(R) gravity, the DGP model, and TeVeS theory. Weak lensing is sensitive to the growth of ... More
On Period Relations for Automorphic L-functions IIApr 14 2016Nov 29 2016We study Hecke algebras for pairs $({\mathfrak g},K)$ over arbitrary fields $E$ of characteristic $0$, define the Bernstein functor and give another definition of the Zuckerman functor over $E$. Building on this and the author's previous work on rational ... More
On Period Relations for Automorphic L-functions IApr 27 2015Nov 16 2017This paper is the first in a series of two dedicated to the study of period relations of the type $$ L(\frac{1}{2}+k,\Pi)\;\in\;(2\pi i)^{d\cdot k}\Omega_{(-1)^k}{\mathbb Q}(\Pi),\quad \frac{1}{2}+k\;\text{critical}, $$ for certain automorphic representations ... More
Modular symbols for reductive groups and p-adic Rankin-Selberg convolutions over number fieldsMar 09 2009May 27 2009We give a construction of a wide class of modular symbols attached to reductive groups. As an application we construct a p-adic distribution interpolating the special values of the twisted Rankin-Selberg L-function attached to cuspidal automorphic representations ... More
Relative Hofer Geometry and the Asymptotic Hofer-Lipschitz ConstantFeb 24 2011Mar 25 2011Let $(M,\omega)$ be a symplectic manifold and $U\subseteq M$ an open subset. I study the natural inclusion of the group of Hamiltonian diffeomorphisms of $U$ into the group of Hamiltonian diffeomorphisms of $M$. The main result is an upper bound for this ... More
Leafwise fixed points for $C^0$-small Hamiltonian flowsAug 20 2014Jul 14 2017Consider a closed coisotropic submanifold $N$ of a symplectic manifold $(M,\omega)$ and a Hamiltonian diffeomorphism $\phi$ on $M$. The main result of this article states that $\phi$ has at least the cup-length of $N$ many leafwise fixed points w.r.t. ... More
Uniform approximation of the integrated density of states for long-range percolation HamiltoniansNov 18 2010In this paper we study the spectrum of long-range percolation graphs. The underlying geometry is given in terms of a finitely generated amenable group. We prove that the integrated density of states (IDS) or spectral distribution function can be approximated ... More
On the strict Arnold chord property and coisotropic submanifolds of complex projective spaceSep 01 2014Jan 19 2015Let $\alpha$ be a contact form on a manifold $M$, and $L\subseteq M$ a closed Legendrian submanifold. I prove that $L$ intersects some characteristic for $\alpha$ at least twice if all characteristics are closed and of the same period, and $\alpha$ embeds ... More
Gravitational Infall onto Molecular FilamentsApr 16 2013Two aspects of filamentary molecular cloud evolution are addressed: (1) Exploring analytically the role of the environment for the evolution of filaments demonstrates that considering them in isolation (i.e. just addressing the fragmentation stability) ... More
Non-Gaussian Halo Bias Beyond the Squeezed LimitApr 05 2013Jun 13 2013Primordial non-Gaussianity, in particular the coupling of modes with widely different wavelengths, can have a strong impact on the large-scale clustering of tracers through a scale-dependent bias with respect to matter. We demonstrate that the standard ... More
The Maxflow problem and a generalization to simplicial complexesDec 05 2012The problem of Maxflow is a widely developed subject in modern mathematics. Efficient algorithms exist to solve this problem, that is why a good generalization may permit these algorithms to be understood as a particular instance of solutions in a wider ... More
A Deligne pairing for Hermitian Azumaya modulesJan 21 2015In this short note we want to give a definition of a generalized Deligne pairing for modules over an Azumaya algebra on an arithmetic surface $X$. We do this by defining Hermitian metrics on the Azumaya algebra and on the modules in question. Then we ... More
Highlights from COMPASS in hadron spectroscopyDec 31 2014Since Quantum Choromdynamics allows for gluon self-coupling, quarks and gluons cannot be observed as free particles, but only their bound states, the hadrons. This so-called confinement phenomenon is responsible for $98\%$ of the mass in the visible universe. ... More
An all-coupling theory for the Fröhlich polaronSep 29 2015The Fr\"ohlich model describes the interaction of a mobile impurity with a surrounding bath of phonons which leads to the formation of a quasiparticle, the polaron. In this article an efficient renormalization group approach is presented which provides ... More
The Vacuum Structure of Vector Mesons in QCDApr 14 2015We study the chiral dynamics of vector mesons in two-flavor QCD in vacuum by utilizing a functional renormalization group approach. This allows us to capture the dynamical transition from the quark-gluon phase at high energies to the hadronic phase at ... More
Asynchronous Distributed Automata: A Characterization of the Modal Mu-FragmentNov 25 2016We establish the equivalence on finite directed graphs between a class of asynchronous distributed automata and a small fragment of least fixpoint logic. More specifically, the logic we consider is (a variant of) the fragment of modal $\mu$-calculus that ... More
Majorana QubitsApr 03 2014Contribution to the 44th IFF Spring School held at the Forschungszentrum J\"ulich in 2013 on "Quantum Information Processing". The notes include a pedagogic (but incomplete) introduction to Majorana fermions; especially paying attention to the usefulness ... More
The nonlinear stochastic Schrödinger equation via stochastic Strichartz estimatesNov 22 2016We consider the stochastic NLS with linear multiplicative noise in $L^2(\mathbb{R}^d)$ and prove the existence and uniqueness of a global solution in the subcritical and a local solution in the critical case, respectively. In particular, we relax the ... More
Framework of two-dimensional functional walksSep 14 2017This paper gives a general introduction to two-dimensional functional walks with particular attention to notation and definition. We also give applications of functional walks and a visual overview of some walks generated by $f(n)=n^2$ and $f(n)=n^3$. ... More
On some dyadic models of the Euler equationsOct 17 2004Oct 19 2004Katz and Pavlovic recently proposed a dyadic model of the Euler equations for which they proved finite time blow-up in the $H^{3/2+\epsilon}$ Sobolev norm. It is shown that their model can be reduced to the dyadic inviscid Burgers equation where nonlinear ... More
p-adic L-functions for Rankin-Selberg convolutions over number fieldsJan 19 2015We unconditionally construct cyclotomic p-adic L-functions for Rankin-Selberg convolutions for GL(n+1) x GL(n) over arbitrary number fields, and show that they satisfy an expected functional equation.
Integral Brauer-Manin obstructions for sums of two squares and a powerApr 03 2013We use Brauer-Manin obstructions to explain failures of the integral Hasse principle and strong approximation away from infinity for the equation x^2+y^2+z^k=m with fixed integers k>=3 and m. Under Schinzel's hypothesis (H), we prove that Brauer-Manin ... More
Algebraic Characters for Harish-Chandra modulesJan 12 2012Oct 25 2013We give a cohomological treatment of a character theory for (g,K)-modules. This leads to a nice formalism extending to large categories of not necessarily admissible (g,K)-modules. Due to results of Hecht, Schmid and Vogan the classical results of Harish-Chandra's ... More
Embedding into bipartite graphsJul 23 2009The conjecture of Bollob\'as and Koml\'os, recently proved by B\"ottcher, Schacht, and Taraz [Math. Ann. 343(1), 175--205, 2009], implies that for any $\gamma>0$, every balanced bipartite graph on $2n$ vertices with bounded degree and sublinear bandwidth ... More
Measurement of the charge asymmetry in top quark pair production in pp collision data at sqrt(s) = 7 TeV using the ATLAS detectorApr 04 2012A measurement of the charge asymmetry in the production of top quark pairs in the semileptonic decay channel has been performed. A dataset corresponding to an integrated luminosity of 1.04 inverse femtobarn, obtained at a centre-of-mass energy of 7 TeV ... More
Yangians in Integrable Field Theories, Spin Chains and Gauge-String DualitiesJan 09 2012In the following paper, which is based on the authors PhD thesis submitted to Imperial College London, we explore the applicability of Yangian symmetry to various integrable models, in particular, in relation with S-matrices. One of the main themes in ... More
The Violent Interstellar Medium of Nearby Dwarf GalaxiesMar 31 1999High resolution HI observations of nearby dwarf galaxies (most of which are situated in the M 81 group at a distance of about 3.2 Mpc) reveal that their neutral interstellar medium (ISM) is dominated by hole-like features most of which are expanding. ... More
State-dependent jump activity estimation for Markovian semimartingalesNov 15 2018The jump behavior of an infinitely active It\^o semimartingale can be conveniently characterized by a jump activity index of Blumenthal-Getoor type, typically assumed to be constant in time. We study Markovian semimartingales with a non-constant, state-dependent ... More
Simultaneous Diophantine approximation on affine subspaces and Dirichlet improvabilityNov 22 2017We show that affine coordinate subspaces of dimension at least two in Euclidean space are of Khintchine type for divergence. For affine coordinate subspaces of dimension one, we prove a result which depends on the dual Diophantine type of the base point ... More
Spectral fluctuations of the atomic vibrations in glasses: random matrix theory and beyondApr 24 2001It is demonstrated on a realistic model of amorphous alloy Si$_{0.9}$Ge$_{0.1}$ with 1000 atoms, that short-range spectral fluctuations of propagons and diffusons are universal and in agreement with random matrix theory. The universality ceases at distances ... More
On the Decay of Localized Vibrational States in Glasses: a one-dimensional exampleOct 14 1996The interaction between three localized vibrational modes is shown to be as relevant for the lifetimes of localized modes as the interaction involving two localized and one extended, and one localized and two extended modes. This contrasts with previous ... More