Results for "Ralf Srama"

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Counter Data of the Cosmic Dust Analyzer aboard the Cassini spacecraft and possible "dust clouds" at SaturnOct 01 2014We present the impact rates of dust particles recorded by the Cosmic Dust Analyzer (CDA) aboard the Cassini spacecraft. The "dust counters" evaluate the quality of an impact and give rise to the apparent density of dust particles in space. The raw data ... More
Jovian Dust Streams: A monitor of Io's volcanic plume activitySep 01 2003Streams of high speed dust particles originate from Jupiter's innermost Galilean moon Io. After release from Io, the particles collect electric charges in the Io plasma torus, gain energy from the co-rotating electric field of Jupiter's magnetosphere, ... More
Techniques for Galactic Dust Measurements in the HeliosphereAug 03 1999Galactic interstellar dust (ISD) is the major ingredient in planetary formation. However, information on this important material has been extremely limited. Recently the Ulysses dust detector has identified and measured interstellar dust outside 1.8~AU ... More
Treating `Free Word Order' in Machine TranslationSep 08 1994In `free word order' languages, every sentence is embedded in its specific context. Among others, the order of constituents is determined by the categories `theme', `rheme' and `contrastive focus'. This paper shows how to recognise and to translate these ... More
Spectroscopic investigation of old planetaries V. Distance scalesDec 01 2000Jan 08 2001We use the results of our recent NLTE model atmosphere analysis of central stars of old planetary nebulae (PN) to calculate distances. We perform a comparison with three other methods (trigonometric parallaxes, interstellar NaD lines, and Shklovsky distances) ... More
SU(2) and SU(3) Yang-Mills thermodynamics and some implicationsMar 30 2006Nov 27 2006We sketch the development of effective theories for SU(2) and SU(3) Yang-Mills thermodynamics. The most important results are quoted and some implications for particle physics and cosmology are discussed.
Yang-Mills thermodynamics: The deconfining phaseJul 04 2005Nov 27 2006We summarize recent nonperturbative results obtained for the thermodynamics of an SU(2) and an SU(3) Yang-Mills theory being in its deconfining (electric) phase. Emphasis is put on an explanation of the concepts involved. The presentation of technical ... More
Non-perturbative non-locality: $V\pm A$ correlators in euclidean position spaceSep 02 2001Using an OPE modification, which takes non-perturbative non-locality into account, the difference and sum of vector and axial-vector correlators are evaluated in euclidean position space. For distances up to 0.8 fm the calculated behavior is close to ... More
Nonperturbative approach to Yang-Mills thermodynamicsApr 07 2005Nov 28 2006An analytical and nonperturbative approach to SU(2) and SU(3) Yang-Mills thermodynamics is developed and applied. Each theory comes in three phases: A deconfining, a preconfining, and a confining one. We show how macroscopic and inert scalar fields form ... More
A thermal theory for charged leptonsDec 03 2003Jan 29 2004We propose that charged leptons are the `baryons' of the gauge dynamics subject to a SU(2)$_{e}$$\timesSU(2)_{\mu}\timesSU(2)_{\tau}$ symmetry. The `mesons' of this theory are neutral and thus candidates for dark matter. There is, in addition, a gauge ... More
Deconfining by WindingApr 19 2001Apr 23 2001A model for the quantum effective description of the vacuum structure of thermalized SU(3) Yang-Mills theory is proposed. The model is based on Abelian projection leading to a Ginzburg-Landau theory for the magnetic sector. The possibility of topologically ... More
BPS Saturated Vacua Interpolation along One Compact DimensionApr 26 2000Jun 08 2000A class of generalized Wess-Zumino models with distinct vacua is investigated. These models allow for BPS saturated vacua interpolation along one compact spatial dimension. The properties of these interpolations are studied.
Dust Emission by AGN and StarburstsJun 24 2005Present AGN and starburst models aiming to account for the observed infrared SEDs consider a physical description of the dust and a solution of the radiative transfer problem. MIR spectra obtained at different spatial scales (SST-IRS, ISO and TIMMI2) ... More
Floer homology of algebraically finite mapping classesApr 02 2002Apr 25 2002We compute the Floer homology of mapping classes which do not have any pseudo-Anosov components in the sense of Thurston's theory of surface diffeomorphisms. The formula for the Floer homology is obtained from a topological separation of fixed points ... More
BMM is stronger than BSPFAMay 02 2003It is shown that if BMM (= Bounded Martin's Maximum) holds then each set is contained in an inner model with a strong cardinal. This answers a question that has been asked by various people. It follows that BMM has a much larger consistency strength than ... More
Supersymmetry at Present and Future CollidersJun 23 1995The theoretical expectations for the supersymmetric particle spectrum is reviewed and a brief overview on present constraints on supersymmetric models from collider experiments is presented. Finally, we discuss the discovery potential of future collider ... More
Top-Down Approach to Unified Supergravity ModelsApr 06 1994Apr 08 1994We introduce a new approach for studying unified supergravity models. In this approach all the parameters of the grand unified theory (GUT) are fixed by imposing the corresponding number of low energy observables. This determines the remaining particle ... More
Neutrino properties and SUSY without $R$-paritySep 30 1996In supersymmetric models without $R$-parity neutrinos naturally become massive and mix with each other. We explore the predictions of a very restricted model with only three free parameters and find that this model naturally yields masses and mixing angles ... More
Book review "The Haskell Road to Logic, Maths and Programming"Dec 24 2005Jun 22 2006The textbook by Doets and van Eijck puts the Haskell programming language systematically to work for presenting a major piece of logic and mathematics. The reader is taken through chapters on basic logic, proof recipes, sets and lists, relations and functions, ... More
Typed Generic Traversal With Term Rewriting StrategiesMay 14 2002Jul 28 2002A typed model of strategic term rewriting is developed. The key innovation is that generic traversal is covered. To this end, we define a typed rewriting calculus S'_{gamma}. The calculus employs a many-sorted type system extended by designated generic ... More
On cluster algebras arising from unpunctured surfaces IISep 15 2008Sep 18 2008We study cluster algebras with principal and arbitrary coefficient systems that are associated to unpunctured surfaces. We give a direct formula for the Laurent polynomial expansion of cluster variables in these cluster algebras in terms of certain paths ... More
GRAPESPH with Fully Periodic Boundary Conditions: Fragmentation of Molecular CloudsApr 01 1997A method of adapting smoothed particle hydrodynamics (SPH) with periodic boundary conditions for use with the special purpose device GRAPE is presented. GRAPE (GRAvity PipE) solves the Poisson and force equations for an N-body system by direct summation ... More
Thermal Ground State in Yang-Mills ThermodynamicsSep 27 2011We derive an a useful priori estimate for the thermal ground state of deconfining phase of SU(2) Yang-Mills thermodynamics in four-dimensional, flat spacetime and discuss its implications. Upon a selfconsistent spatial coarse-graining over noninteracting, ... More
"Exotic" quantum effects in the laboratory?Apr 15 2010This Article provides a brief (non-exhaustive) review of some recent developments regarding the theoretical and possibly experimental study of "exotic" quantum effects in the laboratory with special emphasis on cosmological particle creation, Hawking ... More
CPT and Lorentz violation as signatures for Planck-scale physicsJul 08 2009In recent years, the breakdown of spacetime symmetries has been identified as a promising research field in the context of Planck-scale phenomenology. For example, various theoretical approaches to the quantum-gravity problem are known to accommodate ... More
Photon Polarization Precession Spectroscopy for High-Resolution Studies of SpinwavesFeb 17 2014A new type of spectroscopy for high-resolution studies of spin waves that relies on resonant scattering of hard x-rays is introduced. The energy transfer in the scattering process is encoded in the precession of the polarization vector of the scattered ... More
PICARD: A novel code for the Galactic Cosmic Ray propagation problemJan 16 2014In this manuscript we present a new approach for the numerical solution of the Galactic Cosmic Ray propagation problem. We introduce a method using advanced contemporary numerical algorithms while retaining the general complexity of other established ... More
The QuickReduce data reduction pipeline for the WIYN One Degree ImagerOct 18 2013Optimizing one's observing strategy while at the telescope relies on knowing the current observing conditions and the obtained data quality. In particular the latter is not straight forward with current wide-field imagers, such as the WIYN One Degree ... More
Thermodynamics of SU(2) quantum Yang-Mills theory and CMB anomaliesNov 12 2013A brief review of effective SU(2) Yang-Mills thermodynamics in the deconfining phase is given, including the construction of the thermal ground-state estimate in terms of an inert, adjoint scalar field $\phi$, based on non-propagating (anti)selfdual field ... More
Fundamental and effective SU(2) Yang-Mills verticesOct 05 2012Calorons and plane waves within and in between them {\sl collectively} give rise to a thermal ground state. The latter provides a homgeneous energy density and a negative pressure, and it induces quasiparticle masses to part of the propagating spectrum ... More
Quasi-isospectrality on quantum graphsMar 16 2012Jan 30 2015Consider two quantum graphs with the standard Laplace operator and non-Robin type boundary conditions at all vertices. We show that if their eigenvalue-spectra agree everywhere aside from a sufficiently sparse set, then the eigenvalue-spectra and the ... More
Onset of magnetic monopole-antimonopole condensationAug 27 2009We determine the critical strength of the effective electric coupling for the onset of Bose condensation of stable magnetic monopoles and antimonopoles in SU(2) Yang-Mills thermodynamics. Two scenarios are considered: infinitely fast and infinitely slow ... More
CPT-symmetry studies with antihydrogenApr 28 2016Various approaches to physics beyond the Standard Model can lead to small violations of CPT invariance. Since CPT symmetry can be measured with ultrahigh precision, CPT tests offer an interesting phenomenological avenue to search for underlying physics. ... More
Automatic Test Data Generation and Model Checking with CHRJun 09 2014We present an example for application of Constraint Handling Rules to automated test data generation and model checking in verification of mission critical software for satellite control.
Big Data: Perspektiven fuer Smart Grids und Smart BuildingsOct 21 2016This paper gives a short survey of recent trends in the emerging field of big data. It explains the definitions and useful methods. In addition, application fields of smart buildings and smart grids are discussed.
The Formation of Stellar Clusters: Time Varying Protostellar Accretion RatesJan 16 2001Identifying the processes that determine strength, duration and variability of protostellar mass growth is a fundamental ingredient of any theory of star formation. I discuss protostellar mass accretion rates dM/dt from numerical models which follow molecular ... More
Non-local on-shell field redefinition for the SMESep 23 2006This work instigates a study of non-local field mappings within the Lorentz- and CPT-violating Standard-Model Extension (SME). An example of such a mapping is constructed explicitly, and the conditions for the existence of its inverse are investigated. ... More
Spacetime symmetries and varying scalarsAug 29 2005This talk discusses the relation between spacetime-dependent scalars, such as couplings or fields, and the violation of Lorentz symmetry. A specific cosmological supergravity model demonstrates how scalar fields can acquire time-dependent expectation ... More
Lorentz-violating dispersion relations and threshold analysesFeb 12 2004Remnant low-energy effects of Planck-scale Lorentz breaking in candidate fundamental theories typically include modified one-particle dispersion relations. Theoretical constraints on such modifications are discussed leading to the exclusion of a variety ... More
Fundamental physics and Lorentz violationDec 05 2003The violation of Lorentz symmetry can arise in a variety of approaches to fundamental physics. For the description of the associated low-energy effects, a dynamical framework known as the Standard-Model Extension has been developed. This talk gives a ... More
Defining amalgams of compact Lie groupsAug 11 2007For $n \geq 2$ let $\Delta$ be a Dynkin diagram of rank $n$ and let $I = {1, >..., n}$ be the set of labels of $\Delta$. A group $G$ admits a weak Phan system of type $\Delta$ over $\mathbb{C}$ if $G$ is generated by subgroups $U_i$, $i \in I$, which ... More
A matrix-algebraic algorithm for the Riemannian logarithm on the Stiefel manifoldApr 18 2016May 09 2016We derive a numerical algorithm for evaluating the Riemannian logarithm on the Stiefel manifold with respect to the canonical metric. In contrast to the optimization-based approach known from the literature, we work from a purely matrix-algebraic perspective. ... More
A closed-form update for orthogonal matrix decompositions under arbitrary rank-one modificationsNov 22 2017Jun 08 2018We consider rank-one adaptations $X_{new} = X+ab^T$ of a given matrix $X\in \mathbb{R}^{n\times p}$ with known matrix factorization $X = UW$, where $U\in\mathbb{R}^{n\times p}$ is column-orthogonal, i.e. $U^TU=I$. Arguably the most important methods that ... More
Heat trace asymptotics for quantum graphsDec 12 2012We consider a quantum graph where the operator contains a potential. We show that this operator admits a heat kernel. Under some assumptions on the potential, this heat kernel admits an asymptotic expansion at t=0 with coefficients that depend on the ... More
Categorical aspects of bivariant K-theoryFeb 06 2007Feb 26 2007This survey article on bivariant Kasparov theory and E-theory is mainly intended for readers with a background in homotopical algebra and category theory. We approach both bivariant K-theories via their universal properties and equip them with extra structure ... More
On a representation of the idele class group related to primes and zeros of L-functionsNov 26 2003Mar 16 2005Let K be a global field. Using natural spaces of functions on the adele ring and the idele class group of K, we construct a virtual representation of the idele class group of K whose character is equal to the Weil distribution that occurs in Andre Weil's ... More
Finite dimensional quotients of commutative operator algebrasOct 17 1997The matrix normed structure of the unitization of a (non-selfadjoint) operator algebra is determined by that of the original operator algebra. This yields a classification up to completely isometric isomorphism of two-dimensional unital operator algebras. ... More
Generalized fixed point algebras and square-integrable group actionsNov 13 2000We analzye Rieffel's construction of generalized fixed point algebras in the setting of group actions on Hilbert modules. Let G be a locally compact group acting on a C*-algebra B. We construct a Hilbert module F over the reduced crossed product of G ... More
Cuspidal representations of reductive p-adic groups are relatively injective and projectiveApr 10 2015Nov 21 2015Cuspidal representations of a reductive p-adic group G over a field of characteristic different from p are relatively injective and projective with respect to extensions that split by a U-equivariant linear map for any subgroup U that is compact modulo ... More
The deconfining phase of SU(2) Yang-Mills thermodynamicsJul 17 2006Nov 27 2006We present an overview on nonperturbative thermodynamics in the deconfining phase of an SU(2) Yang-Mills theory. In a unique effective theory the maximal resolution of trivial-topology fluctuations is constrained by coarse-grained, interacting calorons ... More
Nonperturbative and analytical approach to Yang-Mills thermodynamicsApr 29 2004Nov 25 2004An analytical, macroscopic approach to SU(N) Yang-Mills thermodynamics is developed, tested,and applied.
Deconfining by Winding: The Magnetic Monopole Vacua at High TemperaturesJun 15 2000Oct 05 2000Characterizing the vacuum of a thermalized SU(3) Yang-Mills theory in the dual Ginzburg-Landau description, the possibility of topologically nontrivial, classical monopole fields in the deconfining phase is explored. These fields are assumed to be Bogomoln'yi-Prasad-Sommerfield ... More
Gauge boson pair production at LEP and NLCMay 24 1996We compute the dominant one-loop radiative corrections to the cross-section for $e^+ e^- \rightarrow V_1 V_2$ $(V_{1/2} = \gamma, Z, W^\pm$) in the MSSM. We find that the genuine vertex corrections are very small. The oblique corrections are potentially ... More
Lorentz and CPT tests involving antiprotonsFeb 11 2006Lorentz and CPT tests involving matter-antimatter comparisons at low temperatures are discussed. SME predictions for transition frequencies in such systems include both matter-antimatter differences and sidereal variations. In hydrogen-antihydrogen spectroscopy, ... More
SU(2) Yang-Mills Theory: Waves, Particles, and Quantum ThermodynamicsApr 14 2016We elucidate how Quantum Thermodynamics at temperature $T$ emerges from pure and classical SU(2) Yang-Mills theory on a four-dimensional Euclidean spacetime slice $S_1\times {\bf R}^3$. The concept of a (deconfining) thermal ground state, composed of ... More
Vibrational Bandstructures of Bottom-Up Built Nanoscale Phononic CrystalsNov 02 2015The vibrational properties of a phononic crystal assembled from Si nanoparticles and nanowires is studied with large-scale molecular-dynamics simulations. The phonon dispersion relations derived from the simulations show the existence of acoustic band ... More
\nabla_κ, remarkable cardinals, and 0^#May 25 2001For an uncountable regular cardinal \kappa we let \nabla_\kappa(A) be the statement that A \subset \kappa and for all regular \theta > \kappa, the set of all X \in [\theta]^<\kappa such that X \cap \kappa \in \kappa and otp(X \cap OR) is a cardinal in ... More
Spin dependent fragmentatation functions at BelleMay 17 2006Spin dependent fragmentation functions are an important tool to understand the spin structure of the nucleon. The Collins fragmentation function for example describes the fragmentation of a transversely polarized quark into a hadron via the creation of ... More
Heavy-flavor production at RHICMay 14 2005May 19 2005Experimental results on heavy-quark production in proton-proton, deuteron-gold, and gold-gold collisions at sqrt(s_(NN)) = 200 GeV at the Relativistic Heavy Ion Collider (RHIC) are reviewed.
On the Critical Exponent of Infinitely Generated Veech GroupsApr 08 2014We prove the existence of Veech groups having a critical exponent strictly greater than any elementary Fuchsian group (i.e. $>\frac{1}{2}$) but strictly smaller than any lattice (i.e. $<1$). More precisely, every affine covering of a primitive L-shaped ... More
Monodromy of subvarieties of PEL-Shimura varietiesSep 26 2012The aim of this paper is to generalize results of C.-L. Chai about the monodromy of Hecke invariant subvarieties to Shimura varieties of PEL-type.
Refractive index perturbations -- Unruh effect, Hawking radiation or dynamical Casimir effect?Oct 27 2011Motivated by recent experimental progress to manipulate the refractive index of dielectric materials by strong laser beams, we study some aspects of the quantum radiation created by such refractive index perturbations.
A nice acyclic matching on the nerve of the partition latticeApr 12 2012Aug 28 2015The author has already proven that the space \Delta(\Pi_n)/G is homotopy equivalent to a wedge of spheres of dimension n-3 for all natural numbers n>=3 and all subgroups G<S_1 X S_{n-1}. We wish to construct an acyclic matching on \Delta(\Pi_n)/G that ... More
Relativity tests and their motivationFeb 14 2011Some motivations for Lorentz-symmetry tests in the context of quantum-gravity phenomenology are reiterated. The description of the emergent low-energy effects with the Standard-Model Extension (SME) is reviewed. The possibility of constraining such effects ... More
In-Medium Vector Mesons, Dileptons and Chiral RestorationOct 08 2010Medium modifications of the electromagnetic spectral function in hadronic and quark-gluon matter are reviewed. A strong broadening of the $\rho$ meson, which dominates the spectral function in the low-mass regime, is quantitatively consistent with dilepton ... More
Monodromy Groups of Vector Bundles on p-adic CurvesMay 28 2010In [DW05] and [DW07], C. Deninger and A. Werner developed a partial p-adic analogue of the classical Narasimhan-Seshadri correspondence between vector bundles and representations of the fundamental group. We will investigate the various monodromy groups ... More
Tests of Lorentz symmetryAug 10 2010A number of approaches to fundamental physics can lead to the violation of Lorentz and CPT symmetry. This talk discusses the low-energy phenomenology associated with such effects and reviews various sample experiments within this context.
Low-frequency line temperatures of the CMBFeb 16 2009Jul 11 2009Based on SU(2) Yang-Mills thermodynamics we interprete Aracde2's and the results of earlier radio-surveys on low-frequency CMB line temperatures as a phase-boundary effect. We explain the excess at low frequencies by evanescent, nonthermal photon fields ... More
Exoplanet search with astrometryApr 07 2009Searching for extrasolar planets by direct detection is extremely challenging for current instrumentation. Indirect methods, that measure the effect of a planet on its host star, are much more promising and have indeed led to the discovery of nearly all ... More
Divide-and-conquer generating functions. Part I. Elementary sequencesJul 02 2003Divide-and-conquer functions satisfy equations in F(z),F(z^2),F(z^4)... Their generated sequences are mainly used in computer science, and they were analyzed pragmatically, that is, now and then a sequence was picked out for scrutiny. By giving several ... More
On the work of Rodriguez Hertz on rigidity in dynamicsJun 02 2016This paper is a survey about recent progress in measure rigidity and global rigidity of Anosov actions, and celebrates the profound contributions by Federico Rodriguez Hertz to rigidity in dynamical systems.
Discrete Compactness for p-Version of Tetrahedral Edge ElementsJan 07 2009We consider the first family of $\Hcurl$-conforming Ned\'el\'ec finite elements on tetrahedral meshes. Spectral approximation ($p$-version) is achieved by keeping the mesh fixed and raising the polynomial degree $p$ uniformly in all mesh cells. We prove ... More
Cardinal arithmetic and Woodin cardinalsMar 08 2002Suppose that there is a measurable cardinal. If \aleph_\omega is a strong limit cardinal, but the power of \aleph_\omega is bigger than \aleph_{\omega_1}, then there is an inner model with a Woodin cardinal. Modulo the need of the measurable cardinal ... More
Analytic cyclic cohomologyJun 29 1999We prove excision in entire and periodic cyclic cohomology and construct a Chern-Connes character for Fredholm modules over a C*-algebra without summability restrictions, taking values in a variant of Connes's entire cyclic cohomology. Before these results ... More
Bornological versus topological analysis in metrizable spacesOct 15 2003Feb 09 2004Given a metrizable topological vector space, we can also use its von Neumann bornology or its bornology of precompact subsets to do analysis. We show that the bornological and topological approaches are equivalent for many problems. For instance, they ... More
Comparisons between periodic, analytic and local cyclic cohomologyMay 27 2002Dec 18 2003We compute periodic, analytic and local cyclic cohomology for convolution algebras of compact Lie groups in order to exhibit differences between these theories. A surprising result is that the periodic and analytic cyclic cohomology of the smooth convolution ... More
Yang-Mills thermodynamicsOct 04 2007Nov 05 2009We present a quantitative analysis of Yang-Mills thermodynamics in 4D flat spacetime. The focus is on the gauge group SU(2). Results for SU(3) are mentioned in passing. Although all essential arguments and results were reported elsewhere we summarize ... More
Spontaneously broken, local Z$_2$ symmetry and the anatomy of a leptonDec 03 2003Feb 11 2004In the framework of the gauge symmetry ${SU(2)}_{\tiny{CMB}}\times {SU(2)}_{\tiny{e}}\times {SU(2)}_{\tiny{\mu}}\times {SU(2)}_{\tiny{\tau}}$ we provide a microscopic argument why a spontaneously broken, local Z$_2$ symmetry surviving the 1$^{\tiny{st}}$ ... More
Reshuffling the OPE: Delocalized Operator ExpansionJul 29 2002A generalization of the operator product expansion for Euclidean correlators of gauge invariant QCD currents is presented. Each contribution to the modified expansion, which is based on a delocalized multipole expansion of a perturbatively determined ... More
Modifying operator product expansions by non-perturbative non-localitySep 02 2001Nov 12 2001Local quark-hadron duality violations in conventional applications of the operator product expansion are proposed to have their origin in the fact that the QCD vacuum or a hadronic state is not only characterized by nonvanishing expectation values of ... More
Confinement, Chiral Symmetry Breaking, and Axial Anomaly from Domain Formation at Intermediate ResolutionMar 26 2001Jul 02 2001Based on general renormalization group arguments, Polyakov's loop-space formalism, and recent analytical lattice arguments, suggesting, after Abelian gauge fixing, a description of pure gluodynamics by means of a Georgi-Glashow like model, the corresponding ... More
Analytical approach to nonperturbative Yang-Mills thermodynamicsDec 03 2003Dec 05 2003An analytical and inductive approach to hot SU(N) Yang-Mills dynamics is developed. For N=2,3 pressure and energy density are pointwise compared with lattice data.
Towards OPE based local quark-hadron duality: Light-quark channelsSep 02 2001Various light-quark channel current-current correlators are subjected to the concept of a non-perturbative component of coarse graining in operator product expansions introduced in a parallel work. This procedure allows for low-energy structure of the ... More
Neutrino Masses and Mixing Angles in SUSY-GUT Theories with explicit R-Parity BreakingNov 10 1995Sep 10 1996In minimal SUSY GUT models the $R$-parity breaking terms are severely constrained by SU(5) gauge invariance. We consider the particular case where the explicit $R$-parity breaking occurs only via dimension 2 terms of the superpotential. This model possesses ... More
On Hopf algebra structures over free operadsApr 26 2005Nov 30 2005The operad Lie can be constructed as the operad of primitives Prim As from the operad As of associative algebras. This is reflected by the theorems of Friedrichs, Poincare'-Birkhoff-Witt and Cartier-Milnor-Moore. We replace As by families of free operads ... More
Towards Generic RefactoringMar 01 2002We study program refactoring while considering the language or even the programming paradigm as a parameter. We use typed functional programs, namely Haskell programs, as the specification medium for a corresponding refactoring framework. In order to ... More
Neutral pions and eta mesons as probes of the expanding hadronic fireball in nucleus-nucleus collisions at SISMar 02 1998The production of neutral pions and eta mesons in collisions of light, intermediate-mass, and heavy nuclei at beam energies between 0.8 A GeV and 2.0 A GeV is discussed in the framework of a model assuming equilibrium at hadrochemical and thermal freeze-out, ... More
A mapping between Lorentz-violating and conventional electrodynamicsNov 29 2007Feb 17 2011The Chern-Simons-type term in the photon sector of the Lorentz- and CPT-breaking minimal Standard-Model Extension (mSME) is considered. It is argued that under certain circumstances this term can be removed from the mSME. In particular, it is demonstrated ... More
Aspects of spacetime-symmetry violationsFeb 19 2006The violation of spacetime symmetries provides a promising candidate signal for underlying physics, possibly arising at the Planck scale. This talk gives an overview over various aspects in the field, including some mechanisms for Lorentz breakdown, the ... More
Cosmology and spacetime symmetriesAug 31 2005Cosmological models often contain scalar fields, which can acquire global nonzero expectation values that change with the comoving time. Among the possible consequences of these scalar-field backgrounds, an accelerated cosmological expansion, varying ... More
Quantum-gravity phenomenology, Lorentz symmetry, and the SMEMar 16 2007Violations of spacetime symmetries have recently been identified as promising signatures for physics underlying the Standard Model. The present talk gives an overview over various topics in this field: The motivations for spacetime-symmetry research, ... More
Quantum gravity and spacetime symmetriesDec 30 2006Small violations of spacetime symmetries have recently been identified as promising Planck-scale signals. This talk reviews how such violations can arise in various approaches to quantum gravity, how the emergent low-energy effects can be described within ... More
Lorentz violation as a quantum-gravity signatureAug 29 2005Many theoretical approaches to quantum gravity predict the breakdown of Lorentz symmetry at Planck energies. Kinematical cosmic-ray studies are a sensitive tool in the search for such effects. This talk discusses the construction of test dispersion relations ... More
L(R) absoluteness under proper forcingsSep 08 1999We isolate a new large cardinal concept, "remarkability." Consistencywise, remarkable cardinals are between ineffable and omega-Erdos cardinals. They are characterized by the existence of "0^sharp-like" embeddings; however, they relativize down to L. ... More
Lorentz and CPT violation in the Standard-Model ExtensionApr 20 2016Lorentz and CPT invariance are among the symmetries that can be investigated with ultrahigh precision in subatomic physics. Being spacetime symmetries, Lorentz and CPT invariance can be violated by minuscule amounts in many theoretical approaches to underlying ... More
Electromagnetic waves and photonsJul 21 2015Aug 24 2015We explore how the thermal ground states of two mixing and pure SU(2) Yang-Mills theories, SU(2)$_{\tiny\mbox{CMB}}$ of scale $\Lambda_{\tiny\mbox{CMB}}\sim 10^{-4}\,$eV and SU(2)$_{e}$ of scale $\Lambda_{e}\sim 5\times 10^5\,$eV, associate either wave ... More
Relic photon temperature versus redshift and the cosmic neutrino backgroundJul 02 2014Jan 19 2015Presuming that CMB photons are described by the deconfining phase of an SU(2) Yang-Mills theory with the critical temperature for the deconfining-preconfining phase transition matching the present CMB temperature $T_0\sim 2.725\,$K (SU(2)$_{\tiny{CMB}}$), ... More
Kinematical Lorentz-symmetry tests at particle collidersMar 24 2014Violations of Lorentz symmetry are typically associated with modifications of one-particle dispersion relations. The physical effects of such modifications in particle collisions often grow with energy, so that ultrahigh-energy cosmic rays provide an ... More
On the geometry of global function fields, the Riemann-Roch theorem, and finiteness properties of S-arithmetic groupsAug 21 2010Jan 30 2011Harder's reduction theory provides filtrations of euclidean buildings that allow one to deduce cohomological and homological properties of S-arithmetic groups over global function fields. In this survey I will sketch the main points of Harder's reduction ... More
Emergent Horizons in the LaboratoryApr 15 2010The concept of a horizon known from general relativity describes the loss of causal connection and can be applied to non-gravitational scenarios such as out-of-equilibrium condensed-matter systems in the laboratory. This analogy facilitates the identification ... More