Results for "Jens Hertkorn"

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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
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
The Fate of the Higgs Mode in a Trapped Dipolar SupersolidJul 22 2019We theoretically investigate the spectrum of elementary excitations of a trapped dipolar quantum gas across the BEC-supersolid phase transition. Our calculations reveal the existence of distinct Higgs and Nambu-Goldstone modes that emerge from the softening ... More
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
M-brane singularity formationDec 09 2008We derive self-similar string solutions in a graph representation, near the point of singularity formation, which can be shown to extend to point-like singularities on M-branes, as well as to the radially symmetric case.
On 7D TFT and 6D chiral CFTJun 13 2002Jul 04 2002We perform a canonical and BRST analysis of a seven-dimensional Chern-Simons theory on a manifold with boundary. The main result is that the 7D theory induces for consistency a chiral two-form on the 6D boundary. We also comment on similar behaviour in ... More
Matrix Models and Lorentz InvarianceJul 30 2010The question of Lorentz invariance in the membrane matrix model is addressed
On The Construction of Zero Energy States in Supersymmetric Matrix Models IIINov 05 1997For a supersymmetric Hamiltonian appearing in the matrix model related to 11 dimensional supermembranes, zero energy states are constructed. A useful symmetry, and an energy-equipartition property is pointed out.
On the Deformation of Time Harmonic FlowsDec 02 1996It is shown that time-harmonic motions of spherical and toroidal surfaces can be deformed non-locally without loosing the existence of infinitely many constants of the motion.
Asymptotic Zero Energy States for SU(N greater or equal 3)Dec 17 1999Some ideas are presented concerning the question which of the harmonic wavefunctions constructed in [hep-th/9909191] may be annihilated by all supercharges.
On M-Algebras, the Quantisation of Nambu-Mechanics, and Volume Preserving DiffeomorphismsFeb 05 1996M-branes are related to theories on function spaces $\cal{A}$ involving M-linear non-commutative maps from $\cal{A} \times \cdots \times \cal{A}$ to $\cal{A}$. While the Lie-symmetry-algebra of volume preserving diffeomorphisms of $T^M$ cannot be deformed ... More
Fundamental Parameters from Precision TestsFeb 12 2001I review how electroweak precision observables can be used to constrain the Higgs boson mass and the strong coupling constant. Implications for physics beyond the Standard Model are also addressed.
Four-Fermi Operators in $e^+$ $e^-$ Annihilation Experiments and Uncertainties in $Z$ Boson PropertiesNov 25 1994We investigate the effects of possible new four-Fermi operators on $e^+$ $e^-$ annihilation experiments. They represent a class of new physics, which has the potential to change the parameters of the $Z$ boson and at the same time interferes with their ... More
Electroweak Physics at LHCJul 28 2006Jul 30 2006The prospects for electroweak physics at the LHC are reviewed focusing mainly on precision studies. This includes projections for measurements of the effective Z pole weak mixing angle, of top quark, W boson, and Higgs scalar properties, and new physics ... More
Implications of Precision Electroweak Measurements for Physics Beyond the SMMar 22 1999We perform a global analysis of electroweak precision measurements to find constraints on physics beyond the Standard Model. In particular, we discuss oblique parameters, which are useful to constrain additional matter fields, as well as extra $Z$ bosons, ... More
Truthful Feedback for Sanctioning Reputation MechanismsMar 15 2012For product rating environments, similar to that of Amazon Reviews, it has been shown that the truthful elicitation of feedback is possible through mechanisms which pay buyer reports contingent on the reports of other buyers. We study whether similar ... More
The Union-Closed Sets Conjecture for Small FamiliesAug 24 2015Aug 25 2015We prove that the union-closed sets conjecture is true for separating union-closed families $\mathcal{A}$ with $|\mathcal{A}| \leq 2\left(m+\frac{m}{\log_2(m)-\log_2\log_2(m)}\right)$ where $m$ denotes the number of elements in $\mathcal{A}$.
On the Combination Procedure of Correlated ErrorsJul 29 2015When averages of different experimental determinations of the same quantity are computed, each with statistical and systematic error components, then frequently the statistical and systematic components of the combined error are quoted explicitly. These ... More
The rectilinear Steiner tree problem with given topology and length restrictionsDec 16 2014We consider the problem of embedding the Steiner points of a Steiner tree with given topology into the rectilinear plane. Thereby, the length of the path between a distinguished terminal and each other terminal must not exceed given length restrictions. ... More
Science with CMB spectral distortionsMay 27 2014The measurements of COBE/FIRAS have shown that the CMB spectrum is extremely close to a perfect blackbody. There are, however, a number of processes in the early Universe that should create spectral distortions at a level which is within reach of present ... More
4pi Models of CMEs and ICMEsMar 28 2012Coronal mass ejections (CMEs), which dynamically connect the solar surface to the far reaches of interplanetary space, represent a major anifestation of solar activity. They are not only of principal interest but also play a pivotal role in the context ... More
Solitaire Chess is NP-completeJan 26 2015"Solitaire Chess" is a logic puzzle published by Thinkfun, that can be seen as a single person version of traditional chess. Given a chess board with some chess pieces of the same color placed on it, the task is to capture all pieces but one using only ... More
Tautological classes and smooth bundles over BSU(2)Feb 06 2018For a Lie group G and a smooth manifold W, we study the difference between smooth actions of G on W and bundles over the classifying space of G with fiber W and structure group Diff(W). In particular, we exhibit smooth manifold bundles over BSU(2) that ... More
Theory of Drop FormationNov 02 2001We consider the motion of an axisymmetric column of Navier-Stokes fluid with a free surface. Due to surface tension, the thickness of the fluid neck goes to zero in finite time. After the singularity, the fluid consists of two halves, which constitute ... More
Air entrainment through free-surface cuspsNov 14 2000In many industrial processes, such as pouring a liquid or coating a rotating cylinder, air bubbles are entrapped inside the liquid. We propose a novel mechanism for this phenomenon, based on the instability of cusp singularities that generically form ... More
Singularities in droplet pinching with vanishing viscosityApr 30 1997Jan 26 1999A slender-jet model for the pinching of a liquid column is considered in the limit of vanishing viscosity. We find the model to develop a singularity in the gradients of the local radius and the velocity at a finite thread radius, so it does not describe ... More
Diffusion phenomena for partially dissipative hyperbolic systemsOct 04 2011Jan 28 2014In this note we provide some precise estimates explaining the diffusive structure of partially dissipative systems with time-dependent coefficients satisfying a uniform Kalman rank condition. Precisely, we show that under certain (natural) conditions ... More
Thermo-elasticity for anisotropic media in higher dimensionsSep 18 2011In this note we develop tools to study the Cauchy problem for the system of thermo-elasticity in higher dimensions. The theory is developed for general homogeneous anisotropic media under non-degeneracy conditions. For degenerate cases a method of treatment ... More
On t-dependent hyperbolic systems. Part 2Aug 11 2015Oct 18 2016We consider hyperbolic equations with time-dependent coefficients and develop an abstract framework to derive the asymptotic behaviour of the representation of solutions for large times. We are dealing with generic situations where the large-time asymptotics ... More
Coamoebas of polynomials supported on circuitsJan 20 2016We study coamoebas of polynomials supported on circuits. Our results include an explicit description of the space of coamoebas, a relation between connected components of the coamoeba complement and critical points of the polynomial, an upper bound on ... More
Chiral spin-wave excitations of the spin-5/2 trimers in the langasite compound Ba3NbFe3Si2O14Jun 06 2011The inelastic scattering of neutrons from magnetic excitations in the antiferromagnetic phase of the langasite compound Ba3NbFe3Si2O14 is analyzed theoretically. In the calculations presented, the strongly coupled spin-5/2 Fe triangles are accounted for ... More
The Gutzwiller Trace Formula for Quantum Systems with SpinApr 10 2001The Gutzwiller trace formula provides a semiclassical approximation for the density of states of a quantum system in terms of classical periodic orbits. In its original form Gutzwiller derived the trace formula for quantum systems without spin. We will ... More
Borchers' Commutation Relations for Sectors with Braid Group Statistics in Low DimensionsJun 11 2008Jul 10 2008Borchers has shown that in a translation covariant vacuum representation of a theory of local observables with positive energy the following holds: The (Tomita) modular objects associated with the observable algebra of a fixed wedge region give rise to ... More
Star Formation in the Galactic Center EnvironmentDec 05 2017A brief overview of recent advances in the study of star formation in the Galactic Center (GC) environment is presented. Particular attention is paid to new insights concerning the suppression of star formation in GC molecular clouds. Another focus is ... More
Lectures on Minimal SurfacesMar 28 2019Some elementary considerations are presented concerning Catenoids and their stability, separable minimal hypersurfaces, minimal surfaces obtainable by rotating shapes, minimal tori in S3, and the minimality in Rnk of the ordered set of k orthogonal equal-length ... More
Grothendieck topologies on posetsNov 25 2018Lindenhovius has studied Grothendieck topologies on posets and has given a complete classification in the case that the poset is Artinian. We extend his approach to more general posets, by translating known results in locale and domain theory to the study ... More
On the additive period length of the Sprague-Grundy function of certain Nim-like gamesFeb 17 2019Aug 25 2019We examine the structure of the additive period of the Sprague-Grundy function of Nim-like games, among them Wythoff's Game, and deduce a bound for the length of the period and preperiod.
A Serre-Swan theorem for bundles of bounded geometryFeb 14 2013The Serre-Swan theorem in differential geometry establishes an equivalence between the category of smooth vector bundles over a smooth compact manifold and the category of finitely generated projective modules over the unital ring of smooth functions. ... More
Pair correlation and equidistribution on manifoldsMar 02 2019Jun 06 2019This study is motivated by a series of recent papers that show that, if a given deterministic sequence in the unit interval has a Poisson pair correlation function, then the sequence is uniformly distributed. Analogous results have been proved for point ... More
Schwarzschild modelling of elliptical galaxies and their black holesJul 21 2010This article describes the Schwarzschild orbit superposition method. It is the state-of-the-art dynamical modelling tool for early-type galaxies. Tests with analytic models show that masses and orbital anisotropies of not too face-on galaxies can be recovered ... More
Asymptotic properties of solutions to weakly dissipative wave equations below scalingJun 25 2004Jul 27 2004The aim of this paper is to understand the influence of a dissipative term which is small in the sense that it is asymptotically below scaling on the asymptotic properties of solutions. A diagonalization procedure is applied in order to construct the ... More
Exterior powers of F-zipsSep 16 2014An F-zip over a field of positive characteristic is a vector space together with two filtrations whose subquotients are related in a certain way. We will define the category of F-zips and some basic constructions in it, especially exterior powers. If ... More
Electroweak Precision Tests of the SMAug 20 2019A global survey of weak mixing angle measurements at low and high energies is presented. Then I will discuss theoretical uncertainties in precision observables with special emphasis on their correlations. The important role of vacuum polarization in global ... More
Chromatic weight systems and the corresponding knot invariantsJan 13 1997This paper contains a proof that chromatic weight systems, introduced by Chmutov, Duzhin and Lando, can be expressed in terms of weight systems associated with direct sums of the Lie algebras gl_n and so_n. As a consequence the Vassiliev invariants of ... More
Anomaly Cancellation in Six DimensionsApr 22 1993I show that anomaly cancellation conditions are sufficient to determine the two most important topological numbers relevant for Calabi-Yau compactification to six dimensions. This reflects the fact that K3 is the only non-trivial CY manifold in two complex ... More
Low Energy Tests of the Standard Model with Spin Degrees of FreedomDec 04 2006Feb 19 2007After briefly reviewing the status of the standard model, I will focus mainly on polarized electron scattering and other tests of the weak neutral current. I will also address other low energy tests in which polarization degrees of freedom play a crucial ... More
Breakdown of Duality in (0,2) Superstring ModelsJun 16 1993After pointing out the role of the compactification lattice for spectrum calculations in orbifold models, I discuss modular discrete symmetry groups for $Z_N$ or\-bi\-folds. I consider the $Z_7$ orbifold as a nontrivial example of a (2,2) model and give ... More
U(1) invariant Membranes and SingularitiesMay 30 2008A formulation of U(1) - symmetric classical membrane motions (preserving one rotational symmetry) is given, and reductions to systems of ODE's, as well as some ideas concerning singularities and integrability.
M-brane dynamical symmetry and quantizationJan 22 2011The recently discovered dynamical symmetry for relativistic extended objects is derived from first principles, and analogues commutators are obtained for the corresponding formal quantum expressions
Star Formation in the Galactic CenterNov 21 2016Research on Galactic Center star formation is making great advances, in particular due to new data from interferometers spatially resolving molecular clouds in this environment. These new results are discussed in the context of established knowledge about ... More
Tests of the Electroweak Standard ModelSep 14 2012Sep 24 2012Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ranging from the lowest to the highest energy experiments. Results from global fits are presented with particular emphasis on the extraction of fundamental ... More
The Depth-Restricted Rectilinear Steiner Arborescence Problem is NP-completeAug 27 2015In the rectilinear Steiner arborescence problem the task is to build a shortest rectilinear Steiner tree connecting a given root and a set of terminals which are placed in the plane such that all root-terminal-paths are shortest paths. This problem is ... More
Tropical multiplier sequencesMay 23 2015We prove that the diagonal operator defined by a positive sequence preserves tropical and central indices if and only if the sequence is log-concave. In particular we obtain an elementary proof of that such an operator preserves the set of sign-independently ... More
SM vacuum stability and the Weyl consistency conditions: Counting to threeJul 27 2015We demonstrate how a new perturbative ordering may result from the structure of the Weyl anomaly. Respecting the abelian nature of the Weyl anomaly at the lowest order enforces the use of beta functions calculated to a different loop order for different ... More
Time-optimal bath-induced unitaries by Zermelo navigation: speed limit and non-Markovian quantum computationJul 31 2015The solution of the quantum Zermelo navigation problem is applied to the non-Markovian open system dynamics of a set of quantum systems interacting with a common environment. We consider a case allowing an exact time-optimal realization of environment-mediated ... More
Toward a description of contact line motion at higher capillary numbersDec 31 2003The surface of a liquid near a moving contact line is highly curved owing to diverging viscous forces. Thus, microscopic physics must be invoked at the contact line and matched to the hydrodynamic solution farther away. This matching has already been ... More
Hydrodynamic theory of de-wettingDec 24 2003A prototypical problem in the study of wetting phenomena is that of a solid plunging into or being withdrawn from a liquid bath. In the latter, de-wetting case, a critical speed exists above which a stationary contact line is no longer sustainable and ... More
Dynamics of nanojetsJan 02 2002We study the breakup of a liquid jet a few nanometers in diameter, based on a stochastic differential equation derived recently by Moseler and Landman [Science {\bf 289}, 1165 (2000)]. In agreement with their simulations, we confirm that noise qualitatively ... More
Selberg's trace formula: an introductionJul 16 2004Feb 13 2008These lecture notes provide a basic introduction to Selberg's trace formula. We discuss the simplest possible case: the spectrum of the Laplacian on a compact Riemannian surface of constant negative curvature. (To appear in Springer LNP.)
A non-periodic and two-dimensional example of elliptic homogenizationNov 25 2008Aug 13 2009The focus in this paper is on elliptic homogenization of a certain kind of possibly non-periodic problems. A non-periodic and two-dimensional example is studied, where we numerically illustrate the homogenized matrix.
Semiclassical expectation values for relativistic particles with spin 1/2Sep 29 2000For relativistic particles with spin 1/2, which are described by the Dirac equation, a semiclassical trace formula is introduced that incorporates expectation values of observables in eigenstates of the Dirac-Hamiltonian. Furthermore, the semiclassical ... More
Energy conserving Anisotropic Anhysteretic Magnetic Modelling for Finite Element AnalysisDec 20 2012To model ferromagnetic material in finite element analysis a correct description of the constitutive relationship (BH-law) must be found from measured data. This article proposes to use the energy density function as a centrepiece. Using this function, ... More
1/z-renormalization of the mean-field behavior of the dipole-coupled singlet-singlet system HoF_3Dec 15 1993The two main characteristics of the holmium ions in HoF_3 are that their local electronic properties are dominated by two singlet states lying well below the remaining 4f-levels, and that the classical dipole-coupling is an order of magnitude larger than ... More
Mean-field model of the ferromagnetic ordering in the superconducting phase of ErNi_2B_2CJan 09 2002A mean-field model explaining most of the details in the magnetic phase diagram of ErNi_2B_2C is presented. The low-temperature magnetic properties are found to be dominated by the appearance of long-period commensurate structures. The stable structure ... More
A topological groupoid representing the topos of presheaves on a monoidJun 06 2019Butz and Moerdijk famously showed that every (Grothendieck) topos with enough points is equivalent to the category of sheaves on some topological groupoid. We give an alternative, more algebraic construction in the special case of a topos of presheaves ... More
Transfer Learning in the Field of Renewable Energies -- A Transfer Learning Framework Providing Power Forecasts Throughout the Lifecycle of Wind Farms After Initial Connection to the Electrical GridJun 03 2019In recent years, transfer learning gained particular interest in the field of vision and natural language processing. In the research field of vision, e.g., deep neural networks and transfer learning techniques achieve almost perfect classification scores ... More
Precision Electroweak Measurements at Run 2 and BeyondApr 26 2017After reviewing the key features of the global electroweak fit, I will provide updated results and offer experimental and theoretical contexts. I will also make the case for greater precision and highlight future directions.
Which spectral distortions does $Λ$CDM actually predict?Mar 08 2016May 20 2016Ever refined cosmological measurements have established the $\Lambda$CDM concordance model, with the key cosmological parameters being determined to percent-level precision today. This allows us to make explicit predictions for the spectral distortions ... More
Theoretical Implications of Precision MeasurementsOct 17 2017Results of an updated global electoweak fit to the Standard Model (SM) are presented, where special attention is paid to some key observables, such as the weak mixing angle, the $W$ boson mass, and the anomalous magnetic moment of the muon. Implications ... More
Beyond the Ultra-Dense Barrier - Paradigm shifts on the road beyond 1000x wireless capacityJun 11 2016It has become increasingly clear that the current design paradigm for mobile broadband systems is not a scalable and economically feasible way to solve the expected future 'capacity crunch', in particular in indoor locations with large user densities. ... More
The CPT and Bisognano-Wichmann Theorems for Anyons and Plektons in d=2+1Feb 25 2009Feb 26 2009We prove the Bisognano-Wichmann and CPT theorems for massive particles obeying braid group statistics in three-dimensional Minkowski space. We start from first principles of local relativistic quantum theory, assuming Poincare covariance and asymptotic ... More
Quantum LeaksMar 28 2005We show that eigenfunctions of the Laplacian on certain non-compact domains with finite area may localize at infinity--provided there is no extreme level clustering--and thus rule out quantum unique ergodicity for such systems. The construction is elementary ... More
Block-diagonalisation of matrices and operatorsOct 14 2008In this short note we deal with a constructive scheme to decompose a continuous family of matrices $A(\rho)$ asymptotically as $\rho\to0$ into blocks corresponding to groups of eigenvalues of the limit matrix A(0). We also discuss the extension of the ... More
On Some Microlocal Properties of the Range of a Pseudo-Differential Operator of Principal TypeMar 08 2010Jun 13 2011The purpose of this paper is to obtain microlocal analogues of results by L. H \"ormander about inclusion relations between the ranges of first order differential operators with coefficients in $C^\infty$ which fail to be locally solvable. Using similar ... More
On the existence of the Moller wave operator for wave equations with small dissipative termsOct 07 2002Oct 20 2002The aim of this short note is to reconsider and to extend a former result of K. Mochizuki on the existence of the scattering operator for wave equations with small dissipative terms. Contrary to the approach used by Mochizuki we construct the wave operator ... More
On modular semifinite index theoryNov 28 2011We propose a definition of a modular spectral triple which covers existing examples arising from KMS-states, Podles sphere and quantum SU(2). The definition also incorporates the notion of twisted commutators appearing in recent work of Connes and Moscovici. ... More
On harmonic and asymptotically harmonic homogeneous spacesSep 20 2004Oct 04 2005We classify noncompact homogeneous spaces which are Einstein and asymptotically harmonic. This completes the classification of Riemannian harmonic spaces in the homogeneous case: Any simply connected homogeneous harmonic space is flat, or rank-one symmetric, ... More
Generalized axially symmetric potentials with distributional boundary valuesNov 16 2014Nov 12 2015We study a counterpart of the classical Poisson integral for a family of weighted Laplace differential equations in Euclidean half space, solutions of which are known as generalized axially symmetric potentials. These potentials appear naturally in the ... More
Anisotropic thermo-elasticity in 2D -- Part II: ApplicationsAug 02 2007Nov 15 2007In this note we present concrete applications of the general treatment of anisotropic thermo-elasticity developed in Part I.
Solution Representations for a Wave Equation with Weak DissipationOct 02 2002We consider the Cauchy problem for the weakly dissipative wave equation $$ \bx v+\frac\mu{1+t}v_t=0, \qquad x\in\R^n,\quad t\ge 0, $$ parameterized by $\mu>0$, and prove a representation theorem for its solution using the theory of special functions. ... More
Global fits of the SM parametersAug 20 2019I present a global survey of weak mixing angle measurements and other precision experiments and discuss the issue of correlations of the theoretical uncertainties in precision observables. Hadronic vacuum polarization effects complicate global fits in ... More
Designs and codes in affine geometryMay 12 2016May 23 2016Classical designs and their (projective) q-analogs can both be viewed as designs in matroids, using the matroid of all subsets of a set and the matroid of linearly independent subsets of a vector space, respectively. Another natural matroid is given by ... More
Entry and return times for semi-flowsMay 09 2016Dec 05 2016Haydn, Lacroix and Vaienti [Ann. Probab. 33 (2005)] proved that, for a given ergodic map, the entry time distribution converges in the small target limit, if and only if the corresponding return time distribution converges. The present note explains how ... More
The low-density limit of the Lorentz gas: periodic, aperiodic and randomApr 12 2014The Lorentz gas is one of the simplest, most widely used models to study the transport properties of rarified gases in matter. It describes the dynamics of a cloud of non-interacting point particles in an infinite array of fixed spherical scatterers. ... More
Pair correlation densities of inhomogeneous quadratic formsOct 14 2002Apr 20 2004Under explicit diophantine conditions on $(\alpha,\beta)\in\RR^2$, we prove that the local two-point correlations of the sequence given by the values $(m-\alpha)^2+\break (n-\beta)^2$, with $(m,n)\in\ZZ^2$, are those of a Poisson process. This partly ... More
Fit to Electroweak Precision DataJun 12 2006A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is presented. The global fit to all data including the most recent results on the masses of the top quark and the W boson reinforces the preference for a relatively ... More
The Probability Density of the Higgs Boson MassOct 15 2000Jan 11 2001The LEP Collaborations have reported a small excess of events in their combined Higgs boson analysis at center of mass energies up to about 208 GeV. In this communication, I present the result of a calculation of the probability distribution function ... More
Implications of Precision Electroweak Measurements for the Standard Model Higgs BosonApr 05 1999We summarize the status of the Standard Model with special emphasis on the extraction of the Higgs boson mass using Bayesian inference.
Calculation of the QED Coupling alpha (M_Z) in the Modified Minimal-Subtraction SchemeMar 26 1998Nov 09 1998I calculate the QED coupling, alpha, directly in the MS-bar scheme using an unsubtracted dispersion relation for the three light quarks, and perturbative QCD for charm and bottom quarks. Compact analytical expressions are presented, making this approach ... More
Alpha_s with GAPPFeb 27 2011Details are provided how GAPP evaluates the strong coupling constant from Z and tau decays and the corresponding uncertainties.
Radiative Corrections and Z'Sep 29 2009Radiative corrections to parity violating deep inelastic electron scattering are reviewed including a discussion of the renormalization group evolution of the weak mixing angle. Recently obtained results on hypothetical Z' bosons - for which parity violating ... More
Electroweak Precision Data and New Gauge BosonsJul 05 2009I review constraints on the Standard Model (SM) Higgs boson from high energy electroweak (EW) precision data. The same data set also strongly limits various mixing effects of hypothetical extra neutral gauge bosons (Z') with the ordinary Z. I also discuss ... More
Constraining Electroweak PhysicsOct 16 2003I summarize the status of the Standard Model after the 2003 summer conferences.
Electroweak Radiative Corrections to Semileptonic Tau DecaysNov 22 2002Nov 25 2002I present an update on the electroweak radiative correction factor to semileptonic tau decays, including a next-to-leading order resummation of large logarithms. My result differs both qualitatively and quantitatively from the one recently obtained by ... More
Chiral Models of Weak Scale SupersymmetryJun 05 2000I discuss supersymmetric extensions of the Standard Model containing an extra U(1)' gauge symmetry which provide a solution to the mu-problem and at the same time protect the proton from decaying via dimension 4 operators. Moreover, all fields are protected ... More
Asymmetric Orbifolds and Higher Level ModelsFeb 07 1996Nov 29 1996I introduce a class of string constructions based on asymmetric orbifolds leading to level two models. In particular, I derive in detail various models with gauge groups $E_6$ and SO(10), including a four generation $E_6$ model with two adjoint representations. ... More
The SLD Asymmetry in View of the LEP ResultsJun 30 1994LEP determines $\sin^2 \theta_{\rm eff}$, by combining the various asymmetry measurements to be $0.2321 \pm 0.0005$. On the other hand, the left-right asymmetry as measured at SLC corresponds to \seff = $0.2292 \pm 0.0010$. I will discuss the possibilities ... More
Quantum Group Structure and Local Fields in the Algebraic Approach to 2D GravityDec 21 1994This review contains a summary of work by J.-L. Gervais and the author on the operator approach to 2d gravity. Special emphasis is placed on the construction of local observables -the Liouville exponentials and the Liouville field itself - and the underlying ... More
Non-linear realization of Poincare invariance in the graph-representation of extremal hypersurfacesJun 03 2008In the Born-Infeld 'harmonic gauge' description of M-branes moving in R^{M+1} the underlying M+2 dimensional Poincare - invariance gives rise to an interesting system of conservation laws showing signs of integrability.
Surface Motions and Fluid DynamicsMay 02 1994Jul 20 1994A certain class of surface motions, including those of a relativistic membrane minimizing the 3-dimensional volume swept out in Minkowski-space, is shown to be equivalent to 3-dimensional steady-state irrotational inviscid isentropic gas-dynamics. The ... More