Results for "A. D. K. Finck"

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Anomalous modulation of a zero bias peak in a hybrid nanowire-superconductor deviceDec 05 2012Mar 23 2013We report on sub-gap transport measurements of an InAs nanowire coupled to niobium nitride leads at high magnetic fields. We observe a zero-bias anomaly (ZBA) in the differential conductance of the nanowire for certain ranges of magnetic field and chemical ... More
Exciton Condensation and Perfect Coulomb DragMar 14 2012Coulomb drag is a process whereby the repulsive interactions between electrons in spatially separated conductors enable a current flowing in one of the conductors to induce a voltage drop in the other. If the second conductor is part of a closed circuit, ... More
Exciton Transport and Andreev Reflection in a Bilayer Quantum Hall SystemDec 19 2010Jun 06 2011We demonstrate that counterflowing electrical currents can move through the bulk of the excitonic quantized Hall phase found in bilayer two-dimensional electron systems (2DES) even as charged excitations cannot. These counterflowing currents are transported ... More
Quantum Hall Exciton Condensation at Full Spin PolarizationNov 12 2009Using Coulomb drag as a probe, we explore the excitonic phase transition in quantum Hall bilayers at nu=1 as a function of Zeeman energy, E_Z. The critical layer separation d/l for exciton condensation initially increases rapidly with E_Z, but then reaches ... More
Exciton Transport in a Bilayer Quantum Hall SuperfluidSep 26 2012Bilayer quantum Hall systems at \nu =1 support an excitonic ground state. In addition to the usual charged quasiparticles, this system possesses a condensate degree of freedom: exciton transport. Detection of this neutral transport mode is facilitated ... More
Charge Imbalance and Bilayer 2D Electron Systems at $ν_T = 1$Aug 08 2008Nov 19 2008We use interlayer tunneling to study bilayer 2D electron systems at $\nu_T = 1$ over a wide range of charge density imbalance, $\Delta \nu =\nu_1-\nu_2$, between the two layers. We find that the strongly enhanced tunneling associated with the coherent ... More
Area dependence of interlayer tunneling in strongly correlated bilayer 2D electron systems at $ν_T=1$May 15 2008The area and perimeter dependence of the Josephson-like interlayer tunneling signature of the coherent $\nu_T=1$ quantum Hall phase in bilayer two-dimensional electron systems is examined. Electrostatic top gates of various sizes and shapes are used to ... More
Robust Fabry-Perot interference in dual-gated Bi$_2$Se$_3$ devicesMar 24 2015May 03 2016We study Fabry-Perot interference in hybrid devices, each consisting of a mesoscopic superconducting disk deposited on the surface of a three-dimensional topological insulator. Such structures are hypothesized to contain protected zero modes known as ... More
Phase Coherence and Andreev Reflection in Topological Insulator DevicesMar 21 2014Nov 04 2014Topological insulators (TIs) have attracted immense interest because they host helical surface states. Protected by time-reversal symmetry, they are robust to non-magnetic disorder. When superconductivity is induced in these helical states, they are predicted ... More
Evidence for an anomalous current phase relation in topological insulator Josephson junctionsJul 29 2013Jun 01 2015Josephson junctions with topological insulator weak links can host low energy Andreev bound states giving rise to a current phase relation that deviates from sinusoidal behaviour. Of particular interest are zero energy Majorana bound states that form ... More
Dynamical Gate Tunable Supercurrents in Topological Josephson JunctionsFeb 14 2014Jun 05 2014Josephson junctions made of closely-spaced conventional superconductors on the surface of 3D topological insulators have been proposed to host Andreev bound states (ABSs) which can include Majorana fermions. Here, we present an extensive study of the ... More
Spin and the Coulomb Gap in the Half-Filled Lowest Landau LevelJul 21 2016Aug 25 2016The Coulomb gap observed in tunneling between parallel two-dimensional electron systems, each at half filling of the lowest Landau level, is found to depend sensitively on the presence of an in-plane magnetic field. Especially at low electron density, ... More
Tunneling at $ν_T=1$ in Quantum Hall BilayersAug 28 2013Oct 18 2013Interlayer tunneling measurements in the strongly correlated bilayer quantized Hall phase at $\nu_T=1$ are reported. The maximum, or critical current for tunneling at $\nu_T=1$, is shown to be a well-defined global property of the coherent phase, insensitive ... More
Search for excited states in $^{25}$OOct 12 2017Theoretical calculations suggest the presence of low-lying excited states in $^{25}$O. Previous experimental searches by means of proton knockout on $^{26}$F produced no evidence for such excitations. We search for excited states in $^{25}$O using the ... More
Search for unbound 15Be states in the 3n+12Be channelJan 13 201515Be is expected to have low-lying 3/2+ and 5/2+ states. A first search did not observe the 3/2+ [A. Spyrou et al., Phys. Rev. C 84, 044309 (2011)], however, a resonance in 15Be was populated in a second attempt and determined to be unbound with respect ... More
Study of two-neutron radioactivity in the decay of 26OMar 11 2013A new technique was developed to measure the lifetimes of neutron unbound nuclei in the picosecond range. The decay of 26O -> 24O+n+n was examined as it had been predicted to have an appreciable lifetime due to the unique structure of the neutron-rich ... More
Observation of a low-lying neutron-unbound state in 19CMay 03 2013Proton removal reactions from a secondary 22N beam were utilized to populate unbound states in neutron-rich carbon isotopes. Neutrons were measured with the Modular Neutron Array (MoNA) in coincidence with carbon fragments. A resonance with a decay energy ... More
Exploring the Low-$Z$ Shore of the Island of Inversion at $N = 19$Jan 05 2012The technique of invariant mass spectroscopy has been used to measure, for the first time, the ground state energy of neutron-unbound $^{28}\textrm{F},$ determined to be a resonance in the $^{27}\textrm{F} + n$ continuum at $2\underline{2}0 (\underline{5}0)$ ... More
Observation of Ground-State Two-Neutron DecayNov 09 2012Neutron decay spectroscopy has become a successful tool to explore nuclear properties of nuclei with the largest neutron-to-proton ratios. Resonances in nuclei located beyond the neutron dripline are accessible by kinematic reconstruction of the decay ... More
Exploring the neutron dripline two neutrons at a time: The first observations of the 26O and 16Be ground state resonancesAug 14 2012The two-neutron unbound ground state resonances of $^{26}$O and $^{16}$Be were populated using one-proton knockout reactions from $^{27}$F and $^{17}$B beams. A coincidence measurement of 3-body system (fragment + n + n) allowed for the decay energy of ... More
Two-Neutron Sequential Decay of $^{24}$ODec 08 2015A two-neutron unbound excited state of $^{24}$O was populated through a (d,d') reaction at 83.4 MeV/nucleon. A state at $E = 715 \pm 110$ (stat) $\pm 45 $ (sys) keV with a width of $\Gamma < 2$ MeV was observed above the two-neutron separation energy ... More
Search for $^{21}$C and constraints on $^{22}$CApr 16 2013A search for the neutron-unbound nucleus $^{21}$C was performed via the single proton removal reaction from a beam of 22 N at 68 MeV/u. Neutrons were detected with the Modular Neutron Array (MoNA) in coincidence with $^{20}$C fragments. No evidence for ... More
Unconventional Josephson junctions with topological Kondo insulator weak linksAug 06 2019Proximity-induced superconductivity in three dimensional (3D) topological insulators forms a new quantum phase of matter and accommodates exotic quasiparticles such as Majorana bound states. One of the biggest drawbacks of the commonly studied 3D topological ... More
Exploiting neutron-rich radioactive ion beams to constrain the symmetry energyOct 03 2013The Modular Neutron Array (MoNA) and 4 Tm Sweeper magnet were used to measure the free neutrons and heavy charged particles from the radioactive ion beam induced 32Mg + 9Be reaction. The fragmentation reaction was simulated with the Constrained Molecular ... More
Spectroscopy of neutron-unbound $^{27,28}$FMar 07 2012The ground state of $^{28}$F has been observed as an unbound resonance $2\underline{2}0$ keV above the ground state of $^{27}$F. Comparison of this result with USDA/USDB shell model predictions leads to the conclusion that the $^{28}$F ground state is ... More
Microscopic Study of Superdeformed Rotational Bands in 151TbDec 17 1996Structure of eight superdeformed bands in the nucleus 151Tb is analyzed using the results of the Hartree-Fock and Woods-Saxon cranking approaches. It is demonstrated that far going similarities between the two approaches exist and predictions related ... More
A Large Area Timing RPCMar 26 2001A large area Resistive Plate Chamber (RPC) with a total active surface of 160x10 cm2 was built and tested. The surface was segmented in two 5 cm wide strips readout on both ends with custom, very high frequency, front end electronics. A timing resolution ... More
Observation of the First Excited State in 23OAug 20 2007The first excited state in neutron-rich 23O was observed in a (2p1n) knock-out reaction from 26Ne on a beryllium target at a beam energy of 86 MeV/A. The state is unbound with respect to neutron emission and was reconstructed from the invariant mass from ... More
Exploring Neutron-Rich Oxygen Isotopes with MoNAAug 20 2007The Modular Neutron Array (MoNA) was used in conjunction with a large-gap dipole magnet (Sweeper) to measure neutron-unbound states in oxygen isotopes close to the neutron dripline. While no excited states were observed in 24O, a resonance at 45(2) keV ... More
Population of neutron unbound states via two-proton knockout reactionsAug 20 2007The two-proton knockout reaction 9Be(26Ne,O2p) was used to explore excited unbound states of 23O and 24O. In 23O a state at an excitation energy of 2.79(13) MeV was observed. There was no conclusive evidence for the population of excited states in 24O. ... More
Selective population and neutron decay of the first excited state of semi-magic O-23Dec 21 2006We have observed an excited state in the neutron-rich semi-magic nucleus O-23 for the first time. No such states have been found in previous searches using gamma-ray spectroscopy. The observation of a resonance in n-fragment coincidence measurements confirms ... More
Three-body correlations in the ground-state decay of 26OMar 20 2015Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound O26 can provide information on the ground-state wave function, which has been predicted to have a dineutron configuration ... More
Zero degree measurements of 12C fragmentation at 95 MeV/nucleon on thin targetsJul 01 2014During therapeutic treatments using ions such as carbon, nuclear interactions between the incident ions and nuclei present in organic tissues may occur, leading to the attenuation of the incident beam intensity and to the production of secondary light ... More
Neutron knockout of 12Be populating neutron-unbound states in 11BeApr 01 2011Apr 15 2011Neutron-unbound resonant states of 11Be were populated in neutron knock-out reactions from 12Be and identified by 10Be-n coincidence measurements. A resonance in the decay-energy spectrum at 80(2) keV was attributed to a highly excited unbound state in ... More
Evidence for the ground-state resonance of 26OFeb 17 2012Evidence for the ground state of the neutron-unbound nucleus 26O was observed for the first time in the single proton-knockout reaction from a 82 MeV/u 27F beam. Neutrons were measured in coincidence with 24O fragments. 26O was determined to be unbound ... More
Prototype tests for the ALICE TRDFeb 26 2001A Transition Radiation Detector (TRD) has been designed to improve the electron identification and trigger capability of the ALICE experiment at the Large Hadron Collider (LHC) at CERN. We present results from tests of a prototype of the TRD concerning ... More
Rigorous Bounds on the Performance of a Hybrid Dynamical Decoupling-Quantum Computing SchemeMar 30 2008We study dynamical decoupling in a multi-qubit setting, where it is combined with quantum logic gates. This is illustrated in terms of computation using Heisenberg interactions only, where global decoupling pulses commute with the computation. We derive ... More
Spin Splitting in Quantum Wires with Perturbed Axial SymmetryNov 26 2001We investigate theoretically perturbations to the confining potential capable of lifting spin degeneracy in axially symmetric quasi-one-dimensional electron gases with the spin-orbit interaction. The role of two different types of perturbations breaking ... More
Characterization of the reorientation transition in classical Heisenberg models with dipole interactionAug 29 1995In this paper the thermodynamics of thin ferromagnetic films are studied in the framework of the classical Heisenberg model with uniaxial anisotropy and long--range dipole interaction. The dependence of the order of the reorientation transition in these ... More
Fractal dust model of the Universe based on Mandelbrot's Conditional Cosmological Principle and General Theory of RelativityJun 18 2002We present a fractal dust model of the Universe based on Mandelbrot's proposal to replace the standard Cosmological Principle by his Conditional Cosmological Principle within the framework of General Theory of Relativity. This model turns out to be free ... More
The orientation of elliptical galaxiesSep 11 2010We determine the orientations of the light distribution of individual elliptical galaxies by combining the profiles of photometric data from the literature with triaxial models. The orientation is given by a Bayesian probability distribution. The likelihood ... More
On the reorientation transition of ultra-thin Ni/Cu(001) filmsDec 30 1998The reorientation transition of the magnetization of ferromagnetic films is studied on a microscopic basis within a Heisenberg spin model. Using a modified mean field formulation it is possible to calculate properties of magnetic thin films with non-integer ... More
Fermi-Dirac corrections to relic abundancesNov 09 1992We derive an equation for the evolution of the number density of a massive particle species in the early Universe, which correctly accounts for the Fermi-Dirac (FD) statistics. The FD-corrections are sizable and potentially important if the decoupling ... More
Influence of magnetic fields on the spin reorientation transition in ultra-thin filmsMar 02 1999The dependence of the spin reorientation transition in ultra-thin ferromagnetic films on external magnetic fields is studied. For different orientations of the applied field with respect to the film, phase diagrams are calculated within a mean field theory ... More
Electromagnetic energy in a dispersive metamaterialMar 23 2006An expression for the electromagnetic field energy density in a dispersive, lossy, left-handed metamaterial, consisting of an array of split-ring resonators and an array of wires is derived. An electromagnetic field with general time-dependence is considered. ... More
Fault-Tolerant Quantum Dynamical DecouplingAug 20 2004Sep 08 2005Dynamical decoupling pulse sequences have been used to extend coherence times in quantum systems ever since the discovery of the spin-echo effect. Here we introduce a method of recursively concatenated dynamical decoupling pulses, designed to overcome ... More
The Ginsparg-Wilson relation and local chiral random matrix theoryMay 19 1998May 20 1998A chiral random matrix model with locality is constructed and examined. The Nielsen-Ninomiya no-go theorem is circumvented by the use of a generally applicable modified Dirac operator which respects the Ginsparg-Wilson relation. We observe the expected ... More
The AKNS Hierarchy Integrability Analysis Revisited: The Vertex Operator Approach and its Lie-Algebraic StructureDec 05 2010Jul 16 2011A regular approach to studying the Lax type integrability of the AKNS hierarchy of nonlinear Lax type integrable dynamical systems in the vertex operator representation is devised. The relationship with the Lie-algebraic integrability scheme is analyzed, ... More
Theory of the Spin Reorientation Transition of Ultra-Thin Ferromagnetic FilmsSep 25 1998The reorientation transition of the magnetization of ferromagnetic films is studied on a microscopic basis within Heisenberg spin models. Analytic expressions for the temperature dependent anisotropy are derived from which it is seen that the reduced ... More
Reorientation transition of ultrathin ferromagnetic filmsJan 08 1997Aug 28 1997We demonstrate that the reorientation transition from out-of-plane to in-plane magnetization with decreasing temperature as observed experimentally in Ni-films on Cu(001) can be explained on a microscopic basis. Using a combination of mean field theory ... More
Dynamical Decoupling Using Slow Pulses: Efficient Suppression of 1/f NoiseNov 14 2002May 23 2003The application of dynamical decoupling pulses to a single qubit interacting with a linear harmonic oscillator bath with $1/f$ spectral density is studied, and compared to the Ohmic case. Decoupling pulses that are slower than the fastest bath time-scale ... More
Non-radiating and radiating configurations driven by left-handed metamaterialsNov 13 2005It is shown that a pair of identical emitters (e.g. wire dipole antennas) in the focal points of a disc, made of left-handed metamaterial (a "perfect" lens), form a non-radiating electromagnetic configuration. The emitters are fed with voltages of equal ... More
On the origin of double main-sequence turn-offs in star clusters of the Magellanic CloudsDec 03 2008Recent observational studies of intermediate-age star clusters (SCs) in the Large Magellanic Cloud (LMC) have reported that a significant number of these objects show double main-sequence turn-offs (DMSTOs) in their color-magnitude diagrams (CMDs). One ... More
Monte-Carlo study of the reorientation transition in Heisenberg models with dipole interactionsJan 31 1995We simulated the classical two-dimensional anisotropic Heisenberg model with full long range dipole interaction with an algorithm especially designed for long range models. The results show strong evidence for a first order reorientation transition at ... More
Simulation Studies of Some Voronoi Point ProcessesNov 01 2006We introduce a new class of dynamic point process models with simple and intuitive dynamics that are based on the Voronoi tessellations generated by the processes. Under broad conditions, these processes prove to be ergodic and produce, on stabilisation, ... More
Comparison of two analysis methods for nuclear reaction measurements of 12C +12C interactions at 95 MeV/u for hadrontherapyMar 31 2013During therapeutic treatment with heavier ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the ... More
Double di ffential fragmentation cross sections measurements of 95 MeV/u 12C on thin targets for hadrontherapyJun 03 2013During therapeutic treatment with heavy ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the surrounding ... More
Anisotropy of ultra-thin ferromagnetic films and the spin reorientation transitionFeb 28 2002The influence of uniaxial anisotropy and the dipole interaction on the direction of the magnetization of ultra-thin ferromagnetic films in the ground-state is studied. The ground-state energy can be expressed in terms of anisotropy constants which are ... More
Coupled polar-axial magnetar oscillationsDec 15 2011May 07 2012We study coupled axial and polar axisymmetric oscillations of a neutron star endowed with a strong magnetic field, having both poloidal and toroidal components. The toroidal component of the magnetic field is driving the coupling between the polar and ... More
Radiation enhancement and radiation suppression by a left-handed metamaterialMay 06 2006The perfect lens property of a dispersive and lossy left-handed metamaterial (LHM) disk is exploited to superimpose a source of electromagnetic radiation onto its mirror image, formed as a result of reflection from a perfect electric conductor (PEC) or ... More
Quantum Computing in the Presence of Detected Spontaneous EmissionJan 20 2003Jun 18 2005A new method for quantum computation in the presence of detected spontaneous emission is proposed. The method combines strong and fast (dynamical decoupling) pulses and a quantum error correcting code that encodes $n$ logical qubits into only $n+1$ physical ... More
B -> X_s gamma in Supersymmetry with Explicit CP ViolationJul 31 2001Oct 16 2001We discuss B -> X_s gamma decay in both constrained and unconstrained supersymmetric models with explicit CP violation within the minimal flavor violation scheme by including tan(beta) -enhanced large contributions beyond the leading order. In this analysis, ... More
On multidimensional solutions in the Einstein-Gauss-Bonnet model with a cosmological termFeb 17 2016A D-dimensional gravitational model with Gauss-Bonnet and cosmological term is considered. When ansatz with diagonal cosmological metrics is adopted, we overview recent solutions for zero cosmological term and find new examples of solutions for non-zero ... More
Maximum entropy and the problem of moments: A stable algorithmDec 27 2004We present a technique for entropy optimization to calculate a distribution from its moments. The technique is based upon maximizing a discretized form of the Shannon entropy functional by mapping the problem onto a dual space where an optimal solution ... More
Effect of baryon density on parton production, chemical equilibration and thermal photon emission from quark gluon plasmaDec 15 1999The effect of baryon density on parton production processes of $gg\rightleftharpoons ggg$ and $gg\rightleftharpoons q{\bar q}$ is studied using full phase space distribution function and also with inclusion of quantum statistics i.e. Pauli blocking and ... More
Chemical equilibration and thermal dilepton production from the quark gluon plasma at finite baryon densityMay 05 1999The chemical equilibration of a highly unsaturated quark-gluon plasma has been studied at finite baryon density. It is found that in the presence of small amount of baryon density, the chemical equilibration for gluon becomes slower and the temperature ... More
Carrier envelope phase effects in ultrafast, strong-field ionization dynamics of multielectron systems: Xe and CS$_2$Jan 16 2013Carrier envelope phase (CEP) stabilized 5 fs and 22 fs pulses of intense 800 nm light are used to probe the strong-field ionization dynamics of multielectron entities, xenon and carbon disulfide. We compare ion yields obtained with and without CEP-stabilization: ... More
Control of the Onset of Filamentation in Condensed MediaAug 09 2007Propagation of intense, ultrashort laser pulses through condensed media like crystals of BaF$_2$ and sapphire results in the formation of filaments. We demonstrate that the onset of filamentation may be controlled by rotating the plane of polarization ... More
Brans-Dicke theory: Jordan vs Einstein FrameMay 19 2006It is well known that, in contrast to general relativity, there are two conformally related frames, the Jordan frame and the Einstein frame, in which the Brans-Dicke theory, a prototype of generic scalar-tensor theory, can be formulated. There is a long ... More
Thermal Quantum Fields in Static Electromagnetic BackgroundsFeb 24 2000We present and discuss, at a general level, new mathematical results on the spatial nonuniformity of thermal quantum fields coupled minimally to static background electromagnetic potentials. Two distinct examples are worked through in some detail: uniform ... More
Integrals of motion and Robertson-Schrödinger correlated states of electromagnetic field in time-dependent linear mediaSep 28 2010Apr 07 2015Integrals of motion and statistical properties of quantized electromagnetic field (e.-m. field) in time-dependent linear dielectric and conductive media are considered, using Choi-Yeon quantization, based on Caldirola-Kanai type Hamiltonian. Eigenstates ... More
A Preliminary Study of Oxidation of Lignin from Rubber Wood to Vanillin in Ionic Liquid MediumJun 11 2013In this study, lignin was oxidised to vanillin by means of oxygen in ionic liquid (1,3-dimethylimidazolium methylsulphate) medium. The parameters of the oxidation reaction that have been investigated were the following: concentration of oxygen (5, 10, ... More
Bond-selective fragmentation of water molecules with intense, ultrafast, carrier envelope phase stabilized laser pulsesJul 29 2013Carrier envelope phase (CEP) stabilized pulses of intense 800 nm light of 5 fs duration are used to probe the dissociation dynamics of dications of isotopically-substituted water, HOD. HOD$^{2+}$ dissociates into either H$^+$ + OD$^+$ or D$^+$ + OH$^+$. ... More
All-optical Control of the Propagation of Intense Laser Light in Condensed MediaAug 09 2006We experimentally demonstrate optical control of filamentation that occurs during propagation of intense, ultrashort laser pulses through crystals like barium fluoride and sapphire. Control is exercised by rotating the plane of polarization of the incident ... More
Dissipative phenomena in chemically non-equilibrated quark gluon plasmaAug 14 1999The dissipative corrections to the hydrodynamic equations describing the evolution of energy-momentum tensor and parton densities are derived in a simple way using the scaling approximation for the expanding quark gluon plasma at finite baryon density. ... More
Intrinsic Shapes of Very Flat Elliptical GalaxiesOct 27 2010Photometric data from the literature is combined with triaxial mass models to derive variation in the intrinsic shapes of the light distribution of elliptical galaxies NGC 720, 2768 and 3605. The inferred shape variation in given by a Bayesian probability ... More
Change of the charge modulation during superconducting transition in SmFeAsO(0.91)F(0.09) seen by 57Fe Mössbauer spectroscopySep 11 2015Nov 03 2015Iron-based superconductor SmFeAsO(0.91)F(0.09) has been investigated by the 57Fe Moessbauer spectroscopy versus temperature with the special attention paid to the region of the superconducting transition at about 47 K. Modulation of the electron charge ... More
Direct photon production in d+Au collisions at sqrt(s_NN)=200 GeVAug 06 2012Direct photons have been measured in sqrt(s_NN)=200 GeV d+Au collisions at midrapidity. A wide p_T range is covered by measurements of nearly-real virtual photons (1<p_T<6 GeV/c) and real photons (5<p_T<16 GeV/c). The invariant yield of the direct photons ... More
Some formal results for the valence bond basisMay 03 2006In a system with an even number of SU(2) spins, there is an overcomplete set of states--consisting of all possible pairings of the spins into valence bonds--that spans the S=0 Hilbert subspace. Operator expectation values in this basis are related to ... More
5s correlation confinement resonances in Xe-endo-fullerenesSep 24 2011Spectacular trends in the modification of the Xe 5s photoionization via interchannel coupling with confinement resonances emerging in the Xe 4d giant resonance upon photoionization of the Xe@C60, Xe@C240 and Xe@C60@C240 endo-fullerenes are theoretically ... More
Constraints on the Magnetic Field Geometry of MagnetarsNov 09 2007Oct 03 2008We study the effect of the magnetic field geometry on the oscillation spectra of strongly magnetized stars. The magnetic field distributions include both toroidal and poloidal contributions. We observe that the toroidal contribution does not influence ... More
Baryogenesis from Gravitational Decay of TeV-Particles in Theories with Low Scale GravityDec 02 2006Mar 07 2007In models with the fundamental gravity scale in the TeV range, early cosmology is quite different from the standard picture, because the universe must have arisen at a much lower temperature and the electroweak symmetry was probably never restored. In ... More
Statistics of eigenstates near the localization transition on random regular graphsOct 26 2018Dynamical and spatial correlations of eigenfunctions as well as energy level correlations in the Anderson model on random regular graphs (RRG) are studied. We consider the critical point of the Anderson transition and the delocalized phase. In the delocalized ... More
Distance Bounds on Quantum DynamicsMar 29 2008We derive rigorous upper bounds on the distance between quantum states in an open system setting, in terms of the operator norm between the Hamiltonians describing their evolution. We illustrate our results with an example taken from protection against ... More
Chromospheric Emission from Red Giants in the Open Cluster NGC 6940Oct 24 1997The observation of the Ca II H and K lines in red giants in NGC 6940 allows the strength of chromospheres and their behavior to be evaluated in a population whose evolution is well understood. Spectra in the Ca II lines have been obtained for giant stars ... More
Higgs-strahlung in Abelian Extended Supersymmetric Standard ModelSep 13 1998We analyze the Higgs production via the Higgs-strahlung process $e^{+}e^{-}\to h_{k}{\it{l}}^{+}{\it{l}}^{-}$ in an Abelian Extended Supersymmetric SM. We work in the large Higgs trilinear coupling driven minimum of the potential, and find that the next-to-lightest ... More
A Mechanism for Coronal Hole JetsApr 24 2008Bald patches are magnetic topologies in which the magnetic field is concave up over part of a photospheric polarity inversion line. A bald patch topology is believed to be the essential ingredient for filament channels and is often found in extrapolations ... More
An Exact Local Hybrid Monte Carlo Algorithm for Gauge TheoriesNov 16 1993We introduce a new Monte Carlo method for pure gauge theories. It is not intended for use with dynamical fermions. It belongs to the class of Local Hybrid Monte Carlo (LHMC) algorithms, which make use of the locality of the action by updating individual ... More
Production and Backreaction of Fermions from Axion-$SU(2)$ Gauge Fields during InflationMay 22 2019$SU(2)$ gauge fields and axions can have a stable, isotropic and homogeneous configuration during inflation. However, couplings to other matter species lead to particle production, which in turn induces backreaction on and destabilization of the non-abelian ... More
Capillary Rise in Nanopores: Molecular Dynamics Evidence for the Lucas-Washburn EquationMar 30 2007When a capillary is inserted into a liquid, the liquid will rapidly flow into it. This phenomenon, well studied and understood on the macroscale, is investigated by Molecular Dynamics simulations for coarse-grained models of nanotubes. Both a simple Lennard-Jones ... More
A close look at the Centaurus A group of galaxies: I. Metallicity distribution functions and population gradients in early-type dwarfsFeb 01 2010We study dwarf galaxies in the Centaurus A group to investigate their metallicity and possible environmental effects. The Centaurus A group (at ~4 Mpc from the Milky Way) contains about 50 known dwarf companions of different morphologies and stellar contents, ... More
Oka's lemma, convexity, and intermediate positivity conditionsDec 21 2011A new proof of Oka's lemma is given for smoothly bounded, pseudoconvex domains $D\subset\mathbb{C}^n$. The method of proof is then also applied to other convexity-like hypotheses on the boundary of $D$.
A microscopic model for exchange biasJun 18 2001The domain state model for exchange bias has been further investigated by considering vector spins for the antiferromagnet instead of Ising spins used in the earlier studies. The qualitative results are similar to those with infinite anisotropy for the ... More
Modeling exchange bias microscopicallyMar 14 2002Mar 15 2002Exchange bias is a horizontal shift of the hysteresis loop observed for a ferromagnetic layer in contact with an antiferromagnetic layer. Since exchange bias is related to the spin structure of the antiferromagnet, for its fundamental understanding a ... More
Off-diagonal parton distributions and their evolutionJul 26 1998Aug 12 1998We construct off-diagonal parton distributions defined on the interval 0 < X < 1 starting from the off-forward distributions defined by Ji. We emphasize the particular role played by the symmetry relations in the "ERBL-like" region. We find the evolution ... More
A smoothing property of the Bergman projectionOct 26 2010Let B be the Bergman projection associated to a domain on which the dbar-Neumann operator is compact. We show that arbitrary L^2 derivatives of Bf are controlled by derivatives of f taken in a single, distinguished direction. As a consequence, functions ... More
Total variation approximation for quasi-equilibrium distributions, IIMay 31 2011Quasi-stationary distributions, as discussed by Darroch & Seneta (1965), have been used in biology to describe the steady state behaviour of population models which, while eventually certain to become extinct, nevertheless maintain an apparent stochastic ... More
Diagnostics of the Coronal Hole and the adjacent Quiet Sun by The Hinode/EUV Imaging Spectrometer (EIS)Sep 03 2014A comparison between a Coronal Hole (CH) and the adjacent Quiet-Sun (QS) has been performed using spectroscopic diagnostics of Hinode/ the EUV Imaging Spectrometer (EIS). Coronal funnels play an important role in the formation and propagation of the nascent ... More
Transverse-energy distributions at midrapidity in $p$$+$$p$, $d$$+$Au, and Au$+$Au collisions at $\sqrt{s_{_{NN}}}=62.4$--200~GeV and implications for particle-production modelsDec 23 2013Measurements of the midrapidity transverse energy distribution, $d\Et/d\eta$, are presented for $p$$+$$p$, $d$$+$Au, and Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV and additionally for Au$+$Au collisions at $\sqrt{s_{_{NN}}}=62.4$ and 130 GeV. The ... More
Collective traffic-like movement of ants on a trail: dynamical phases and phase transitionsNov 26 2004The traffic-like collective movement of ants on a trail can be described by a stochastic cellular automaton model. We have earlier investigated its unusual flow-density relation by using various mean field approximations and computer simulations. In this ... More