Results for "W. Benbow"

total 63104took 0.14s
Upper Limits from HESS Observations of AGN in 2005-2007Sep 28 2007Very high energy (VHE; >100 GeV) observations of a sample of selected active galactic nuclei (AGN) were performed between January 2005 and April 2007 with the High Energy Stereoscopic System (HESS), an array of imaging atmospheric-Cherenkov telescopes. ... More
Multi-wavelength Observations of PG 1553+113 with HESSSep 28 2007Very high energy (VHE; >100 GeV) gamma-ray observations of PG 1553+113 were made with the High Energy Stereoscopic System (HESS) in 2005 and 2006. A strong signal, ~10 standard deviations, is detected by HESS during the 2 years of observations (24.8 hours ... More
A search for Very High Energy gamma-ray emission from Passive Super-massive Black HolesSep 18 2007Jets of Active Galactic Nuclei (AGN) are established emitters of very high energy (VHE; >100 GeV) gamma-rays. VHE radiation is also expected to be emitted from the vicinity of super-massive black holes (SMBH), irrespective of their activity state. Accreting ... More
VERITAS Observations of BlazarsJan 05 2010The VERITAS array of four 12-m diameter imaging atmospheric-Cherenkov telescopes in southern Arizona is used to study very high energy (VHE; E>100 GeV) gamma-ray emission from astrophysical objects. VERITAS is currently the most sensitive VHE gamma-ray ... More
Status of the Schwarzchild-Couder Medium-Sized Telescope for the Cherenkov Telescope ArrayOct 12 2016The Cherenkov Telescope Array (CTA) is planned to be the next-generation very-high-energy (VHE; E > 100 GeV) gamma-ray observatory. It is anticipated that CTA will improve upon the sensitivity of the current generation of VHE experiments, such as VERITAS, ... More
A Survey of the Northern Sky for TeV Point SourcesMar 21 2001May 17 2001A search for steady TeV point sources anywhere in the northern sky has been made with data from the Milagrito air-shower-particle detector. Over 3 x 10**9 events collected from 1997 February to 1998 May have been used in this study. No statistically significant ... More
Discovery of Very High Energy gamma - ray emission from the extreme BL Lac object H2356-309 with H.E.S.SFeb 20 2006The understanding of acceleration mechanisms in active galactic nuclei (AGN) jets and the measurement of the extragalactic-background-light (EBL) density are closely linked and require the detection of a large sample of very-high-energy (VHE) emitting ... More
H.E.S.S. observations of galaxy clustersAug 10 2007Clusters of galaxies, the largest gravitationally bound objects in the universe, are expected to contain a significant population of hadronic and leptonic cosmic rays. Potential sources for these particles are merger and accretion shocks, starburst driven ... More
A Spectacular VHE Gamma-Ray Outburst from PKS 2155-304 in 2006Sep 28 2007Since 2002 the VHE (>100 GeV) gamma-ray flux of the high-frequency peaked BL Lac PKS 2155-304 has been monitored with the High Energy Stereoscopic System (HESS). An extreme gamma-ray outburst was detected in the early hours of July 28, 2006 (MJD 53944). ... More
Observation of the giant radio galaxy M87 at TeV energies with H.E.S.SApr 18 2005The giant radio galaxy M 87 was observed at TeV energies with the Cherenkov telescopes of the H.E.S.S. collaboration (High Energy Stereoscopic System). The observations have been performed in the year 2003 during the comissioning phase and in 2004 with ... More
Highlights from the VERITAS AGN Observation ProgramOct 12 2016The VERITAS array of four 12-m imaging atmospheric-Cherenkov telescopes began full-scale operations in 2007, and is one of the world's most sensitive detectors of astrophysical very high energy (VHE; E>100 GeV) gamma rays. Observations of active galactic ... More
A Search for Pulsed Very High-Energy Gamma Rays from Thirteen Young Pulsars in Archival VERITAS DataApr 19 2019We conduct a search for periodic emission in the very high-energy gamma-ray band (VHE; E > 100 GeV) from a total of 13 pulsars in an archival VERITAS data set with a total exposure of over 450 hours. The set of pulsars includes many of the brightest young ... More
Highlights from the VERITAS AGN Observation ProgramAug 28 2015The VERITAS array of four 12-m imaging atmospheric-Cherenkov telescopes began full-scale operations in 2007, and is one of the world's most sensitive detectors of astrophysical VHE (E>100 GeV) $\gamma$-rays. Observations of active galactic nuclei (AGN) ... More
VHE Blazar Discoveries with VERITASSep 30 2011The VERITAS array of 12-m atmospheric-Cherenkov telescopes is used in an intensive observation program focused on the discovery of VHE (E > 100 GeV) gamma-ray-emitting blazars. Since VERITAS began full-scale operation in 2007, more than 1000 hours of ... More
Highlights of the VERITAS Blazar ProgramOct 12 2012The VERITAS array of 12-m atmospheric-Cherenkov telescopes in southern Arizona began full-scale operations in 2007, and is one of the world's most-sensitive detectors of astrophysical VHE (E>100 GeV) gamma rays. Approximately 50 blazars are known to emit ... More
The VERITAS Blazar Key Science ProjectAug 10 2009The VERITAS array of 12-m atmospheric-Cherenkov telescopes in southern Arizona is currently the world's most-sensitive detector of astrophysical very high energy (VHE; E>100 GeV) gamma rays. Approximately 25 blazars are known to emit VHE photons, and ... More
Highlights of the VERITAS Blazar Observation ProgramSep 30 2011The VERITAS array of 12-m atmospheric-Cherenkov telescopes in southern Arizona began full-scale operations in 2007, and it is one of the world's most sensitive detectors of astrophysical VHE (E > 100 GeV) gamma rays. Forty-one blazars are known to emit ... More
Direct measurement of stellar angular diameters by the VERITAS Cherenkov TelescopesApr 12 2019The angular size of a star is a critical factor in determining its basic properties. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. ... More
Strongly Lensed Jets, Time Delays, and the Value of H0Aug 25 2014Nov 10 2014In principle, the most straightforward method of estimating the Hubble constant relies on time delays between mirage images of strongly-lensed sources. It is a puzzle, then, that the values of H0 obtained with this method span a range from 50 - 100 km/s/Mpc. ... More
Very-High-Energy $γ$-Ray Observations of the Blazar 1ES 2344+514 with VERITASAug 09 2017We present very-high-energy $\gamma$-ray observations of the BL Lac object 1ES 2344+514 taken by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) between 2007 and 2015. 1ES 2344+514 is detected with a statistical significance above ... More
A Medium Sized Schwarzschild-Couder Cherenkov Telescope Mechanical Design Proposed for the Cherenkov Telescope ArraySep 10 2015The Cherenkov Telescope Array (CTA) is an international next-generation ground-based gamma-ray observatory. CTA will be implemented as southern and northern hemisphere arrays of tens of small, medium and large-sized imaging Cherenkov telescopes with the ... More
Constraints on Very High Energy gamma-ray emission from Gamma-Ray BurstsMar 11 2005The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high energy particles interacting in the Earth's atmosphere. Milagro has a wide field of view and high duty cycle, monitoring the northern ... More
Resolving the High Energy Universe with Strong Gravitational Lensing: The Case of PKS 1830-211Apr 20 2015Jul 08 2015Gravitational lensing is a potentially powerful tool for elucidating the origin of gamma-ray emission from distant sources. Cosmic lenses magnify the emission from distance sources and produce time delays between mirage images. Gravitationally-induced ... More
Limits on Very High Energy Emission from Gamma-Ray Bursts with the Milagro ObservatoryNov 17 2003Feb 06 2004The Milagro telescope monitors the northern sky for 100 GeV to 100 TeV transient emission through continuous very high energy wide-field observations. The large effective area and ~100 GeV energy threshold of Milagro allow it to detect very high energy ... More
The high-energy gamma-ray fluence and energy spectrum of GRB 970417a from observations with MilagritoJul 06 2002Evidence of TeV emission from GRB970417a has been previously reported using data from the Milagrito detector. Constraints on the TeV fluence and the energy spectrum are now derived using additional data from a scaler system that recorded the rate of signals ... More
Subtracted Dispersion Relations for In-Medium Meson Correlators in QCD Sum RulesJan 22 1999We analyze subtracted dispersion relations for meson correlators at finite baryon density and temperature. Such relations are needed for QCD sum rules. We point out the importance of scattering terms, as well as finite, well-defined subtraction constants. ... More
Low temperature thermodynamics of inverse square spin models in one dimensionApr 29 1998We present a field-theoretic renormalization group calculation in two loop order for classical O(N)-models with an inverse square interaction in the vicinity of their lower critical dimensionality one. The magnetic susceptibility at low temperatures is ... More
Photodisintegration of the triton with realistic potentialsDec 08 1997The process $\gamma + t \to n + d$ is treated by means of three-body integral equations employing in their kernel the W-Matrix representation of the subsystem amplitudes. As compared to the plane wave (Born) approximation the full solution of the integral ... More
Pac-Learning Recursive Logic Programs: Efficient AlgorithmsMay 01 1995We present algorithms that learn certain classes of function-free recursive logic programs in polynomial time from equivalence queries. In particular, we show that a single k-ary recursive constant-depth determinate clause is learnable. Two-clause programs ... More
Active Galactic Nuclei under the scrutiny of CTAApr 10 2013Active Galactic Nuclei (hereafter AGN) produce powerful outflows which offer excellent conditions for efficient particle acceleration in internal and external shocks, turbulence, and magnetic reconnection events. The jets as well as particle accelerating ... More
Strong gravitational lensing as a tool to investigate the structure of jets at high energiesMar 20 2014Jun 03 2014The components of blazar jets that emit radiation span a factor of $10^{10}$ in scale. The spatial structure of these emitting regions depends on the observed energy. Photons emitted at different sites cross the lens plane at different distances from ... More
Pairwise Comparisons Rating Scale ParadoxNov 24 2015Dec 01 2015This study demonstrates that incorrect data are entered into a pairwise comparisons matrix for processing into weights for the data collected by a rating scale. Unprocessed rating scale data lead to a paradox. A solution to it, based on normalization, ... More
Geometric relation between centrality and the impact parameter in relativistic heavy-ion collisionsOct 08 2001We show, under general assumptions which are well satisfied in relativistic heavy-ion collisions, that the geometric relation of centrality c to the impact parameter b, namely c ~ pi b^2/sigma_inel, holds to a very high accuracy for all but most peripheral ... More
In-Medium Modifications of Hadron Masses and Chemical Freeze-Out in Ultra-Relativistic Heavy-Ion CollisionsOct 06 1999We confront the hypothesis of chemical freeze-out in ultra-relativistic heavy-ion collisions with the hypothesis of large modifications of hadron masses in nuclear medium. We find that the thermal-model predictions for the ratios of particle multiplicities ... More
A Free Field Representation of the Osp(2|2) current algebra at level k=-2, and Dirac Fermions in a random SU(2) gauge potentialDec 11 2000The Osp(2|2) current algebra at level k=-2 is known to describe the IR fixed point of 2D Dirac fermions, subject to a random SU(2) gauge potential. We show that this theory has a simple free-field representation in terms of a compact, and a non-compact ... More
The Single-Electron-Box and the Helicity Modulus of an inverse square XY-ModelDec 19 1996We calculate the average number of electrons on a metallic single-electron-box as a function of the gate voltage for arbitrary values of the tunneling conductance. In the vicinity of the plateaus the problem is equivalent to calculating the helicity modulus ... More
Temperature-dependent quasiparticle band structure of the ferromagnetic semiconductor EuSJun 24 2002We present calculations for the temperature-dependent electronic structure of the ferromagnetic semiconductor EuS. A combination of a many-body evaluation of a multiband Kondo-lattice model and a first-principles T=0--bandstructure calculation (tight-binding ... More
Radiative capture of protons by deuteronsAug 17 1998Sep 03 1998The differential cross section for radiative capture of protons by deuterons is calculated using different realistic NN interactions. We compare our results with the available experimental data below $E_x = 20 MeV$. Excellent agreement is found when taking ... More
Triton photodisintegration with realistic potentialsDec 05 1997The photodisintegration of $^{3}$H is treated by means of coupled integral equations using separable versions of the Paris and the Bonn potentials in their kernel. The differential cross section for the inverse reaction is obtained via detailed balance. ... More
Topological phases: Classification of topological insulators and superconductors of non-interacting Fermions, and beyondDec 30 2015After briefly recalling the quantum entanglement-based view of topological phases of matter in order to outline the general context, we give an overview of different approaches to the classification problem of topological insulators and superconductors ... More
Large lepton flavour violating signals in supersymmetric particle decaysOct 24 2002We study lepton flavour violating signals at a future e+ e- linear collider within the general MSSM, allowing for the most general flavour structure. We demonstrate that there is a large region in parameter space with large signals, while being consistent ... More
An All-Sky Search for Steady VHE Gamma-Ray SourcesJun 23 1999The Milagrito water Cherenkov detector in the Jemez Mountains near Los Alamos, New Mexico took data from February 1997 to April 1998. Milagrito served as a prototype for the larger Milagro detector, which has just begun operations. Milagrito was the first ... More
Calibration of the Milagro Cosmic Ray TelescopeJun 25 1999The Milagro detector is an air shower array which uses the water Cherenkov technique and is capable of continuously monitoring the sky at energies near 1 TeV. The detector consists of 20000 metric tons of pure water instrumented with 723 photo-multiplier ... More
Milagrito Detection of TeV Emission from Mrk 501Jun 24 1999The Milagro water Cherenkov detector near Los Alamos, New Mexico, has been operated as a sky monitor at energies of a few TeV between February 1997 and April 1998. Serving as a test run for the full Milagro detector, Milagrito has taken data during the ... More
VHE gamma-ray emission of PKS 2155-304: spectral and temporal variabilityMay 20 2010May 21 2010Observations of very high energy gamma-rays from blazars provide information about acceleration mechanisms occurring in their innermost regions. Studies of variability in these objects allow a better understanding of the mechanisms at play. To investigate ... More
Status of the Milagro Gamma Ray ObservatoryJun 24 1999The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at ... More
First Results of a Study of TeV Emission from GRBs in MilagritoOct 29 1999Milagrito, a detector sensitive to gamma-rays at TeV energies, monitored the northern sky during the period February 1997 through May 1998. With a large field of view and high duty cycle, this instrument was used to perform a search for TeV counterparts ... More
Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito TelescopeJun 24 1999The Milagrito water Cherenkov telescope operated for over a year. The most probable gamma-ray energy was ~1 TeV and the trigger rate was as high as 400 Hz. We have developed an efficient technique for searching the entire sky for short duration bursts ... More
Search for a TeV Component of GRBs using the Milagrito DetectorJun 24 1999Observing gamma ray bursts (GRBs) in the TeV energy range can be extremely valuable in providing insight to GRB radiation mechanisms and in constraining source distances. The Milagrito detector was an air shower array which used the water Cherenkov technique ... More
Evidence for TeV Emission from GRB 970417aJan 07 2000Milagrito, a detector sensitive to very high energy gamma rays, monitored the northern sky from February 1997 through May 1998. With a large field of view and a high duty cycle, this instrument was well suited to perform a search for TeV gamma-ray bursts ... More
Rigorous QCD-Potential for the $t\bar{t}$-System at ThresholdAug 02 1994Aug 04 1994Recent evidence for the top mass in the region of 160 $GeV$ for the first time provides an opportunity to use the full power of relativistic quantum field theoretical methods, available also for weakly bound systems. Because of the large decay width $\G$ ... More
Weak Coupling Limit and Genuine QCD Predictions for Heavy QuarkoniaAug 03 1994Although individual levels of toponium will be unobservable, the top--anti--top system near threshold fulfills all requirements of a rigorous perturbation theory in QCD for weakly bound systems. Corresponding techniques from positronium may thus be transferred ... More
A note on radial basis function computingJun 03 2001This note carries three purposes involving our latest advances on the radial basis function (RBF) approach. First, we will introduce a new scheme employing the boundary knot method (BKM) to nonlinear convection-diffusion problem. It is stressed that the ... More
Toponium as Nonabelian Positronium ?Jul 01 1993The expected large mass $m_t$ of the top quark provides for the first time a chance to discuss the bound-states of the corresponding quantum system as the nonabelian generalization of positronium, using the full power of relativistic quantum field theoretic ... More
Detection of 6 November 1997 Ground Level Event by MilagritoJun 24 1999Solar Energetic Particles from the 6 November 1997 solar flare/CME(coronal mass ejection) with energies exceeding 10 GeV have been detected by Milagrito, a prototype of the Milagro Gamma Ray Observatory. While particle acceleration beyond 1 GeV at the ... More
Study of the Shadows of the Moon and the Sun with VHE Cosmic RaysJun 24 1999Milagrito, a prototype for the Milagro detector, operated for 15 months in 1997-8 and collected 8.9 billion events. It was the first extensive air shower (EAS) array sensitive to showers intiated by primaries with energy below 1 TeV. The shadows of the ... More
Relativistic Bound State Equation for Unstable Fermions and the Toponium WidthJan 31 1995The bound state problem for a fermion-antifermion system is considered taking into account a finite decay width of the constituents. We propose an exactly solvable relativistic zero order equation similar to that of Barbieri and Remiddi, but including ... More
Gauge-Independent Bound-State Corrections to the Toponium Decay WidthAug 03 1994Off-shell and relativistic bound-state corrections for the decay $t \to b+W$ are calculated to $O(\a_s^2)$ making full use of the Bethe-Salpeter formalism for weakly bound systems. Thus we are able to take into account all terms to that order in a systematic ... More
Large lepton flavor violating signals in supersymmetric particle decays at future e+ e- collidersJan 30 2002We study lepton flavor violating signals at a future e+ e- linear collider within the general MSSM, allowing for the most general flavor structure. We demonstrate that there is a large region in parameter space with large signals, while being consistent ... More
Nucleon Structure Functions from Relativistic Constituent QuarksJun 30 1994We investigate deep inelastic lepton scattering from the nucleon within a constituent quark picture, in which the internal structure of constituent quarks is modeled by meson and diquark dressing. In a covariant framework this structure leads to a breakdown ... More
Pac-learning Recursive Logic Programs: Negative ResultsMay 01 1995In a companion paper it was shown that the class of constant-depth determinate k-ary recursive clauses is efficiently learnable. In this paper we present negative results showing that any natural generalization of this class is hard to learn in Valiant's ... More
On the variability of the GeV and multi-TeV gamma-ray emission from the Crab NebulaNov 18 2010Feb 15 2011Recently the AGILE $\gamma$-ray telescope has reported the enhanced $\gamma$-ray emission above 100 MeV from the direction of the Crab Nebula during a period of a few days. This intriguing observation has been confirmed by the Fermi-LAT telescope. This ... More
Instrumented Water Tanks can Improve Air Shower Detector SensitivityJul 15 1999Previous works have shown that water Cherenkov detectors have superior sensitivity to those of scintillation counters as applied to detecting extensive air showers (EAS). This is in large part due to their much higher sensitivity to EAS photons which ... More
Observation and Spectral Measurements of the Crab Nebula with MilagroOct 03 2011The Crab Nebula was detected with the Milagro experiment at a statistical significance of 17 standard deviations over the lifetime of the experiment. The experiment was sensitive to approximately 100 GeV - 100 TeV gamma ray air showers by observing the ... More
The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studiesFeb 09 2015Feb 10 2015We performed a 4.5-month multi-instrument campaign (from radio to VHE gamma rays) on Mrk421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. ... More
The extreme HBL behaviour of Markarian 501 during 2012Aug 13 2018Aug 14 2018A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift ... More
A Monte Carlo Study of Pairwise ComparisonsMay 07 2015Consistent approximations obtained by geometric means ($GM$) and the principal eigenvector ($EV$), turned out to be close enough for 1,000,000 not-so-inconsistent pairwise comparisons matrices. In this respect both methods are accurate enough for most ... More
Parton distributions from lattice QCDAug 02 2001Sep 27 2001We extract the x dependence of the nonsinglet u-d distribution function in the nucleon from the lowest few moments calculated on the lattice, using an extrapolation formula which ensures the correct behavior in the chiral and heavy quark limits. We discuss ... More
Some recent advances on the RBFJul 26 2002This paper aims to survey our recent work relating to the radial basis function (RBF) and its applications to numerical PDEs. We introduced the kernel RBF involving general pre-wavelets and scale-orthogonal wavelets RBF. A dimension-independent RBF error ... More
SRF Cavity Fabrication and MaterialsJan 28 2015The technological and metallurgical requirements of material for highgradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. ... More
Positive time fractional derivativeOct 07 2002In mathematical modeling of the non-squared frequency-dependent diffusions, also known as the anomalous diffusions, it is desirable to have a positive real Fourier transform for the time derivative of arbitrary fractional or odd integer order. The Fourier ... More
A new definition of the fractional LaplacianSep 18 2002It is noted that the standard definition of the fractional Laplacian leads to a hyper-singular convolution integral and is also obscure about how to implement the boundary conditions. This purpose of this note is to introduce a new definition of the fractional ... More
A direct time-domain FEM modeling of broadband frequency-dependent absorption with the presence of matrix fractional power: Model IAug 20 2002The frequency-dependent attenuation of broadband acoustics is often confronted in many different areas. However, the related time domain simulation is rarely found in literature due to enormous technical difficulty. The currently popular relaxation models ... More
Entanglement moleculesJun 22 2000We investigate the entanglement properties of multiparticle systems, concentrating on the case where the entanglement is robust against disposal of particles. Two qubits -belonging to a multipartite system- are entangled in this sense iff their reduced ... More
Continuous representations of scalar products of Bethe vectorsJul 28 2016Sep 22 2016We present families of single determinantal representations of on-shell scalar products of Bethe vectors. Our families of representations are parameterized by a continuous complex variable which can be fixed at convenience. Here we consider Bethe vectors ... More
The Euclid space-time diagram of the theory of relativityJun 03 2014A conventional space-time diagram is $r-ct$ one, which satisfies the Minkowski geometry. This geometry conflict the intuition from the Euclid geometry. In this work an Euclid space-time diagram is proposed to describe relativistic world lines with an ... More
A new calculation formula of the nuclear cross-section of therapeutic protonsFeb 24 2014We have previously developed for nuclear cross-sections of therapeutic protons a calculation model, which is founded on the collective model as well as a quantum mechanical many particle problem to derive the S matrix and transition probabilities. In ... More
Characterization of specific nuclear reaction channels by deconvolution in the energy space of the total nuclear cross-section of protons - applications to proton therapy and technical problems (transmutations)Apr 28 2016May 06 2016The total nuclear cross-section Qtot(E) resulting from the interaction of protons with nuclei is decomposed in 3 different contributions: 1. elastic scatter at the complete nucleus, which adopts a part of the proton kinetic energy; 2. inelastic scatter ... More
G0.087-0.087, a highly polarized flat spectrum filament near the Galactic Centre ArcFeb 18 200332 GHz observations with the Effelsberg 100-m telescope revealed a highly polarized Galactic Centre filament: G0.087-0.087, running parallel to the well-known Arc structure. It has a similar flat spectrum, but it is an order of magnitude weaker. G0.087-0.087 ... More
Quark-Hadron Duality in Electron ScatteringOct 26 2000Quark-hadron duality addresses some of the most fundamental issues in strong interaction physics, in particular the nature of the transition from the perturbative to non-perturbative regions of QCD. I summarize recent developments in quark-hadron duality ... More
Quark-hadron duality in electron-pion scatteringAug 28 2002Apr 02 2003We explore the relationship between exclusive and inclusive electromagnetic scattering from the pion, focusing on the transition region at intermediate Q^2. Combining Drell-Yan data on the leading twist quark distribution in the pion with a model for ... More
QCD and the Structure of the Nucleon in Electron ScatteringJun 15 2000Aug 28 2001The internal structure of the nucleon is discussed within the context of QCD. Recent progress in understanding the distribution of flavor and spin in the nucleon is reviewed, and prospects for extending our knowledge of nucleon structure in electron scattering ... More
Flavour singlet physics in lattice QCD with background fieldsOct 09 2004Apr 08 2005We show that hadronic matrix elements can be extracted from lattice simulations with background fields that arise from operator exponentiation. Importantly, flavour-singlet matrix elements can be evaluated without requiring the computation of disconnected ... More
Case study: calculation of a narrow resonance with the LIT methodMar 12 2008The possibility to resolve narrow structures in reaction cross sections in calculations with the Lorentz integral transform (LIT) method is studied. To this end we consider a fictitious two-nucleon problem with a low-lying and narrow resonance in the ... More
BPS States, Weight Spaces and Vanishing CyclesJul 03 1995We review some simple group theoretical properties of BPS states, in relation with the singular homology of level surfaces. Primary focus is on classical and quantum N=2 supersymmetric Yang-Mills theory, though the considerations can be applied to string ... More
Performance Limits for Cherenkov InstrumentsMar 03 2006Mar 17 2006The performance of Cherenkov instruments for the detection of very high energy gamma rays is ultimately limited by the fluctuations in the development of air showers. With particular emphasis on the angular resolution, the ultimate performance limits ... More
Flow in the Driven Cavity Calculated by the Lattice Boltzmann MethodJul 08 1994The lattice Boltzmann method with enhanced collisions and rest particles is used to calculate the flow in a two-dimensional lid-driven cavity. The abilitity of this method to compute the velocity and the pressure of an incompressible fluid in a geometry ... More
Dynamical Electroweak Symmetry BreakingMar 04 2003Apr 28 2003Dynamical symmetry breaking provides a possible solution to the electroweak hierarchy problem. It requires new strong interactions that are effective at some high-energy scale. If there is no light Higgs boson, this scale is constrained to be in the TeV ... More
Strong Decays Of Heavy Hadrons In HQETAug 08 1997We discuss the application of the tensor formalism of HQET to the strong decays of heavy hadrons. We treat both meson and baryon decays, and note that all of our results are in agreement with the `spin-counting' arguments of Isgur and Wise. We briefly ... More
Relativity in binary systems as root of quantum mechanics and space-timeAug 14 2004Aug 28 2004Inspired by Bohr's dictum that "physical phenomena are observed relative to different experimental setups", this article investigates the notion of relativity in Bohr's sense, starting from a set of binary elements. The most general form of information ... More
Amplitudes for left-handed stringsDec 08 2015Dec 15 2015We consider a class of string-like models introduced previously where all modes are left-handed, all states are massless, T-duality is manifest, and only a finite number of orders in the string tension can appear. These theories arise from standard string ... More
Introduction to string field theoryJul 11 2001The 1988 book, now free, with corrections and bookmarks (for pdf).
FieldsDec 21 1999Aug 23 2005The first free comprehensive textbook on quantum (and classical) field theory. The approach is pragmatic, rather than traditional or artistic: It includes practical techniques, such as the 1/N expansion (color ordering) and spacecone (spinor helicity), ... More
Hidden Gravity in Open-String Field TheoryDec 14 1993We clarify the nature of the graviton as a bound state in open-string field theory: The flat metric in the action appears as the vacuum value of an OPEN string field. The bound state appears as a composite field in the FREE field theory.
Manifest Duality in Low-Energy SuperstringsAug 27 1993String theories inspire a new formalism for their low-energy limits. In this approach to these field theories, spacetime duality and stringy left/right handedness are manifest. Enlarged tangent-space symmetries allow the different fields (graviton, axion, ... More
AdS/CFT in superspaceMay 13 2010May 25 2010We relate the 10D IIB superstring (primarily free supergravity) expanded about AdS_5\timesS^5 to 4D N=4 Yang-Mills directly in superspace. The sphere becomes the CFT internal space of projective superspace, plus a coordinate counting the number of supergluons. ... More
Actions for QCD-like stringsJan 02 1996We introduce a random lattice corresponding to ordinary Feynman diagrams, with 1/p-squared propagators instead of the Gaussians used in the usual strings. The continuum limit defines a new type of string action with two worldsheet metrics, one Minkowskian ... More
Randomizing the SuperstringMar 23 1994Apr 18 1994We find a simpler formulation of the Green-Schwarz action, for which the Wess-Zumino term is the square of supersymmetric currents, like the rest of the action. On a random lattice it gives Feynman diagrams of a particle superfield theory.
The N=2(4) string is self-dual N=4 Yang-MillsMay 20 1992May 28 1992N=2 string amplitudes, when required to have the Lorentz covariance of the equivalent N=4 string, describe a self-dual form of N=4 super Yang-Mills in 2+2 dimensions. Spin-independent couplings and the ghost nature of SO(2,2) spacetime make it a topological-like ... More
The N=4 string is the same as the N=2 stringApr 02 1992May 28 1992We redo the quantization of the N=4 string, taking into account the reducibility of the constraints. The result is equivalent to the N=2 string, with critical dimension D=4 and signature (++--). The N=4 formulation has several advantages: the sigma-model ... More