Results for "S. J. Haigh"

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Solar Irradiance Variability and ClimateJun 12 2013The brightness of the Sun varies on all time scales on which it has been observed, and there is increasing evidence that it has an influence on climate. The amplitudes of such variations depend on the wavelength and possibly on the time scale. Although ... More
Cavity mediated coherent coupling of magnetic momentsJun 19 2015Jul 06 2015We demonstrate the long range strong coupling of magnetostatic modes in spatially separated ferromagnets mediated by a microwave frequency cavity. Two spheres of yttrium iron garnet are embedded in the cavity and their magnetostatic modes probed using ... More
Optical studies of two LMC X-ray transients : RX J0544.1-7100 and RX J0520.5-6932Jan 11 2001We report observations which confirm the identities of the optical counterpart to the transient sources RX J0544.1-7100 and RX J0520.5-6932. The counterparts are suggested to be a B-type stars. Optical data from the observations carried out at ESO and ... More
Observations of the unusual counterpart to the X-ray pulsar AX J0051-733Jan 18 2002We report optical and IR observations of the ASCA X-ray pulsar system AX J0051-733. The relationship between the X-ray source and possible optical counterparts is discussed. Long term optical data from over 7 years are presented which reveal both a 1.4d ... More
Acceleration Statistics as Measures of Statistical Persistence of Streamlines in Isotropic TurbulenceJul 30 2004Nov 19 2004We introduce the velocity (Vs) of stagnation points as a means to characterise and measure statistical persistence of streamlines. Using theoretical arguments, Direct Numerical Simulations (DNS) and Kinematic Simulations (KS) of three-dimensional isotropic ... More
Machine Learning Approach to RF Transmitter IdentificationNov 05 2017Nov 07 2017With the development and widespread use of wireless devices in recent years (mobile phones, Internet of Things, Wi-Fi), the electromagnetic spectrum has become extremely crowded. In order to counter security threats posed by rogue or unknown transmitters, ... More
Optimized conditions for direct imaging of bonding charge density in electron microscopyAug 25 2010Nov 09 2010We report on the observability of valence bonding effects in aberration-corrected high resolution electron microscopy (HREM) images along the [010] projection of the mineral Forsterite(Mg2SiO4). We have also performed exit wave restorations using simulated ... More
Assessing the relationship between spectral solar irradiance and stratospheric ozone using Bayesian inferenceAug 14 2014We investigate the relationship between spectral solar irradiance (SSI) and ozone in the tropical upper stratosphere. We find that solar cycle (SC) changes in ozone can be well approximated by considering the ozone response to SSI changes in a small number ... More
Magneto-optical coupling in whispering gallery mode resonatorsOct 22 2015Dec 03 2015We demonstrate that yttrium iron garnet microspheres support optical whispering gallery modes similar to those in non-magnetic dielectric materials. The direction of the ferromagnetic moment tunes both the resonant frequency via the Voigt effect as well ... More
Selection rules for cavity-enhanced Brillouin light scattering from magnetostatic modesApr 03 2018Jun 08 2018We experimentally identify the magnetostatic modes active for Brillouin light scattering in the optical whispering gallery modes of a yttrium iron garnet sphere. Each mode is identified by magnetic field dispersion of ferromagnetic-resonance spectroscopy ... More
Sign of tunnel coupling in barrier-separated Bose-Einstein condensates and stability of double-ring systemsMay 28 2008Aug 16 2009We revisit recent claims about the instability of non-rotating tunnel coupled annular Bose-Einstein condensates leading to the emergence of angular-momentum Josephson oscillation [Phys. Rev. Lett. 98, 050401 (2007), arXiv:quant-ph/0609133v2]. It was predicted ... More
Convergent beam electron holography for analysis of van der Waals heterostructuresJul 05 2018Van der Waals heterostructures, which explore the synergetic properties of two-dimensional (2D) materials when assembled into three-dimensional stacks, have already brought to life a number of exciting new phenomena and novel electronic devices. Still, ... More
Convergent and divergent beam electron holography and reconstruction of adsorbates on free-standing two-dimensional crystalsOct 24 2018Van der Waals heterostructures have been lately intensively studied because they offer a large variety of properties that can be controlled by selecting 2D materials and their sequence in the stack. The exact arrangement of the layers as well as the exact ... More
Implementation of a local principal curves algorithm for neutrino interaction reconstruction in a liquid argon volumeDec 20 2013May 14 2014A local principal curve algorithm has been implemented in three dimensions for automated track and shower reconstruction of neutrino interactions in a liquid argon time projection chamber. We present details of the algorithm and characterise its performance ... More
Cyclical behaviour and disc truncation in the Be/X-ray binary A0535+26May 12 2003A0535+26 is shown to display quantised IR excess flux states, which are interpreted as the first observational verification of the resonant truncation scheme proposed by Okazaki and Negueruela (2001) for BeXRBs. The simultaneity of X-ray activity with ... More
Identification of spin wave modes strongly coupled to a co-axial cavityJun 09 2015We demonstrate, at room temperature, the strong coupling of the fundamental and non-uniform magnetostatic modes of an yttrium iron garnet (YIG) ferrimagnetic sphere to the electromagnetic modes of a co-axial cavity. The well-defined field profile within ... More
Ballistic molecular transport through two-dimensional channelsMay 15 2018Gas permeation through nanoscale pores is ubiquitous in nature and plays an important role in a plethora of technologies. Because the pore size is typically smaller than the mean free path of gas molecules, their flow is conventionally described by the ... More
Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlatticesJun 28 2012Sep 04 2012By stacking various two-dimensional (2D) atomic crystals [1] on top of each other, it is possible to create multilayer heterostructures and devices with designed electronic properties [2-5]. However, various adsorbates become trapped between layers during ... More
Transport of hydrogen isotopes through interlayer spacing in van der Waals crystalsFeb 09 2018Atoms start behaving as waves rather than classical particles if confined in spaces commensurate with their de Broglie wavelength. At room temperature this length is only about one angstrom even for the lightest atom, hydrogen. This restricts quantum-confinement ... More
Atomically-thin micas as proton conducting membranesJun 11 2019Monolayers of graphene and hexagonal boron nitride (hBN) are highly permeable to thermal protons. For thicker two-dimensional (2D) materials, proton conductivity diminishes exponentially so that, for example, monolayer MoS2 that is just three atoms thick ... More
Demonstrating mesoscopic superpositions in double-well Bose-Einstein condensatesJul 08 2009The availability of Bose-Einstein condensates as mesoscopic or macroscopic quantum objects has aroused new interest in the possiblity of making and detecting coherent superpositions involving many atoms. In this article we show that it may be possible ... More
The SMC X-ray transient XTE J0111.2-7317 : a Be/X-ray binary in a SNR?Dec 10 1999We report observations which confirm the identity of the optical/IR counterpart to the Rossi X-ray Timing Explorer transient source XTE J0111.2-7317. The counterpart is suggested to be a B0-B2 star (luminosity class III--V) showing an IR excess and strong ... More
Anomalous twin boundaries in 2D materialsSep 01 2018The high mechanical strength and excellent flexibility of 2D materials such as graphene are some of their most important properties [1]. Good flexibility is key for exploiting 2D materials in many emerging technologies, such as wearable electronics, bioelectronics, ... More
Observing imperfection in atomic interfaces for van der Waals heterostructuresJul 25 2017Vertically stacked van der Waals heterostructures are a lucrative platform for exploring the rich electronic and optoelectronic phenomena in two-dimensional materials. Their performance will be strongly affected by impurities and defects at the interfaces. ... More
A low field technique for measuring magnetic and magneto-resistance anisotropy coefficients applied to (Ga,Mn)AsAug 27 2009We demonstrate a simple, low cost, magneto-transport method for rapidly characterizing the magnetic anisotropy and anisotropic magneto-resistance (AMR) of ferromagnetic devices with uniaxial magnetic anisotropy. This transport technique is the analogue ... More
An in- and ex-situ TEM study into the oxidisation of titanium (IV) sulphideMay 29 2015The degradation of liquid dispersed titanium (IV) sulphide (TiS$_2$) is studied from the point of view of oxidisation. TiS$_2$ is a layered two-dimensional nanomaterial, with potential for energy storage applications. However, flakes in dispersion were ... More
Van der Waals pressure and its effect on trapped interlayer moleculesMay 23 2016Van der Waals assembly of two-dimensional (2D) crystals continue attract intense interest due to the prospect of designing novel materials with on-demand properties. One of the unique features of this technology is the possibility of trapping molecules ... More
Laser writable high-K dielectric for van der Waals nano-electronicsNov 12 2018Like silicon-based semiconductor devices, van der Waals heterostructures will require integration with high-K oxides. This is needed to achieve suitable voltage scaling, improved performance as well as allowing for added functionalities. Unfortunately, ... More
Magnetoresistance of vertical Co-graphene-NiFe junctions controlled by charge transfer and proximity-induced spin splitting in grapheneJul 04 2016Jun 16 2017Graphene is hailed as an ideal material for spintronics due to weak intrinsic spin-orbit interaction that facilitates lateral spin transport and tunability of its electronic properties, including a possibility to induce magnetism in graphene. Another ... More
Tuneable Sieving of Ions Using Graphene Oxide MembranesJan 19 2017Graphene oxide membranes show exceptional molecular permeation properties, with a promise for many applications. However, their use in ion sieving and desalination technologies is limited by a permeation cutoff of ~9 Angstrom, which is larger than hydrated ... More
Exchange bias of a ferromagnetic semiconductor by a ferromagnetic metalJan 14 2010We demonstrate an exchange bias in (Ga,Mn)As induced by antiferromagnetic coupling to a thin overlayer of Fe. Bias fields of up to 240 Oe are observed. Using element-specific x-ray magnetic circular dichroism measurements, we distinguish a strongly exchange ... More
Heterostructures produced from nanosheet-based inksSep 04 2014The new paradigm of heterostructures based on two-dimensional (2D) atomic crystals has already led to the observation of exciting physical phenomena and creation of novel devices. The possibility of combining layers of different 2D materials in one stack ... More
Magnetoresistance of vertical Co-graphene-NiFe junctions controlled by charge transfer and proximity-induced spin splitting in grapheneJul 04 2016Jul 13 2016Graphene is hailed as potentially an ideal material for spintronics due to weak intrinsic spin-orbit interaction that facilitates spin transport, and tunability of its electronic properties. Additional functionalities in graphene-based spintronic devices ... More
Molecular transport through capillaries made with atomic-scale precisionJun 29 2016Sep 08 2016Nanometre-scale pores and capillaries have long been studied because of their importance in many natural phenomena and their use in numerous applications. A more recent development is the ability to fabricate artificial capillaries with nanometre dimensions, ... More
The Be/X-ray binary LS 992/RX J0812.4-3114: physical parameters and long-term variabilityNov 15 2000We present the first long-term optical and infrared study of the optical counterpart to the source RX J0812.4-3114, an X-ray pulsar with a Be type companion. During the period covered by the observations the profile of some Balmer lines changed from absorption ... More
Light-emitting diodes by bandstructure engineering in van der Waals heterostructuresDec 24 2014The advent of graphene and related 2D materials has recently led to a new technology: heterostructures based on these atomically thin crystals. The paradigm proved itself extremely versatile and led to rapid demonstration of tunnelling diodes with negative ... More
Phase segregation facilitates exfoliation of franckeite crystals to a single unit cell thicknessDec 08 2016Weak interlayer van der Waals interactions in bulk crystals facilitate their mechanical exfoliation to monolayer and few-layer two-dimensional (2D) materials, which exhibit striking physical phenomena absent in their bulk form. Here we study a 2D form ... More
Disc loss and renewal in A0535+26Oct 20 1999This paper presents observations of the Be/X-ray binary system A0535+26 revealing the first observed loss of its circumstellar disc, demonstrated by the loss of its JHK infrared excess and optical/IR line emission. However optical/IR spectroscopy reveals ... More
Dispersive read-out of ferromagnetic resonance for strongly coupled magnons and microwave photonsJun 18 2015We demonstrate the dispersive measurement of ferromagnetic resonance in a yttrium iron garnet sphere embedded within a microwave cavity. The reduction in the longitudinal magnetization at resonance is measured as a frequency shift in the cavity mode coupled ... More
XTE J0111.2-7317 : a nebula-embedded X-ray binary in the SMCJun 05 2003The observed characteristics of the nebulosity surrounding the SMC High Mass X-ray Binary XTE J0111.2-7317 are examined in the context of three possible nebular types: SNR, bowshock and HII region. Observational evidence is presented which appears to ... More
Triple-resonant Brillouin light scattering in magneto-optical cavitiesJul 11 2016Sep 22 2016An enhancement in Brillouin light scattering of optical photons with magnons is demonstrated in magneto-optical whispering gallery mode resonators tuned to a triple resonance point. This occurs when both the input and output optical modes are resonant ... More
Vertical Field Effect Transistor based on Graphene-WS2 Heterostructures for flexible and transparent electronicsNov 21 2012The celebrated electronic properties of graphene have opened way for materials just one-atom-thick to be used in the post-silicon electronic era. An important milestone was the creation of heterostructures based on graphene and other two-dimensional (2D) ... More
Anisotropic magneto-capacitance in ferromagnetic-plate capacitorsMay 01 2015The capacitance of a parallel plate capacitor can depend on applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction dependent ... More
Efficient conversion of light to charge and spin in Hall-bar microdeviceMay 13 2016We report an experimental demonstration of a local amplification of the spin Hall voltage using an expanding depletion zone at a pn-junction in GaAs/AlGaAs Hall-bar microdevices. It is demonstrated that the depletion zone can be spatially expanded by ... More
Discovery of Pulsed X-rays from the SMC Transient RX J0052.1-7319Jul 09 2001Coherent 65 mHz pulsations in the X-ray flux of the Small Magellantic Cloud (SMC) transient source RX J0052.1-7319 have been detected by us in an analysis of ROSAT data. We report on the pulsations we detected in ROSAT HRI data and simultaneous detection ... More
Electronic Properties of Graphene Encapsulated with Different Two-Dimensional Atomic CrystalsMar 20 2014May 24 2014Hexagonal boron nitride is the only substrate that has so far allowed graphene devices exhibiting micron-scale ballistic transport. Can other atomically flat crystals be used as substrates for making quality graphene heterostructures? Here we report on ... More
Results from T2KJan 18 2015The Tokai to Kamioka (T2K) experiment uses a beam of muon neutrinos, produced at the J-PARC facility on the east coast of Japan, to study neutrino oscillations driven by the $\Delta m_{\textrm{atm}}^{2}$ mass splitting. A suite of near detectors located ... More
Low-temperature tunable radio-frequency resonator for sensitive dispersive readout of nanoelectronic devicesJul 20 2018Mar 27 2019We present a sensitive, tunable radio-frequency resonator designed to detect reactive changes in nanoelectronic devices down to dilution refrigerator temperatures. The resonator incorporates GaAs varicap diodes to allow electrical tuning of the resonant ... More
WSe2 light-emitting tunneling transistors with enhanced brightness at room temperatureNov 19 2015Monolayers of molybdenum and tungsten dichalcogenides are direct bandgap semiconductors, which makes them promising for opto-electronic applications. In particular, van der Waals heterostructures consisting of monolayers of MoS2 sandwiched between atomically ... More
Characterization and Simulation of the Response of Multi Pixel Photon Counters to Low Light LevelsJan 11 2011The calorimeter, range detector and active target elements of the T2K near detectors rely on the Hamamatsu Photonics Multi-Pixel Photon Counters (MPPCs) to detect scintillation light produced by charged particles. Detailed measurements of the MPPC gain, ... More
Structure of $^{13}$Be probed via secondary beam reactionsDec 09 2013Feb 28 2014The low-lying level structure of the unbound neutron-rich nucleus $^{13}$Be has been investigated via breakup on a carbon target of secondary beams of $^{14,15}$B at 35 MeV/nucleon. The coincident detection of the beam velocity $^{12}$Be fragments and ... More
Hall micromagnetometry of individual two-dimensional ferromagnetsFeb 19 2019The recent advent of atomically-thin ferromagnetic crystals has allowed experimental studies of two-dimensional (2D) magnetism that not only exhibits novel behavior due to the reduced dimensionality but also often serves as a starting point for understanding ... More
High solar cycle spectral variations inconsistent with stratospheric ozone observationsFeb 20 2016Some of the natural variability in climate is understood to come from changes in the Sun. A key route whereby the Sun may influence surface climate is initiated in the tropical stratosphere by the absorption of solar ultraviolet (UV) radiation by ozone, ... More
Primary thermometry of a single reservoir using cyclic electron tunneling in a CMOS transistorMay 09 2018May 30 2018Temperature is a fundamental parameter in the study of physical phenomena. At the nanoscale, local temperature differences can be harnessed to design novel thermal nanoelectronic devices or test quantum thermodynamical concepts. Determining temperature ... More
Quality heterostructures from two dimensional crystals unstable in air by their assembly in inert atmosphereFeb 12 2015Many layered materials can be cleaved down to individual atomic planes, similar to graphene, but only a small minority of them are stable under ambient conditions. The rest reacts and decomposes in air, which has severely hindered their investigation ... More
Optical spin transfer torque driven domain wall motion in ferromagnetic semiconductorSep 22 2014Mar 05 2015We demonstrate optical manipulation of the position of a domain wall in a dilute magnetic semiconductor, GaMnAsP. Two main contributions are identified. Firstly, photocarrier spin exerts a spin transfer torque on the magnetization via the exchange interaction. ... More
Nanometer Resolution Elemental Mapping in Graphene-based TEM Liquid CellsOct 18 2017We demonstrate a new design of graphene liquid cell consisting of a thin lithographically patterned hexagonal boron nitride crystal encapsulated from both sides with graphene windows. The ultra-thin window liquid cells produced have precisely controlled ... More
Strain control of magnetic anisotropy in (Ga,Mn)As microbarsJul 16 2010We present an experimental and theoretical study of magnetocrystalline anisotropies in arrays of bars patterned lithographically into (Ga,Mn)As epilayers grown under compressive lattice strain. Structural properties of the (Ga,Mn)As microbars are investigated ... More
Real-Time Experimental Demonstration of Multi-band CAP Modulation in a VLC System with Off-the-Shelf LEDsMar 07 2019We demonstrate, for the first time, m-CAP modulation using off-the-shelf LEDs in a VLC in real time experimental setup using field programmable gate arrays based in universal software radio peripherals (USRPs). We demonstrate transmission speeds up to ... More
Piezoelectric strain induced variation of the magnetic anisotropy in a high Curie temperature (Ga,Mn)As sampleMay 16 2012We show that effective electrical control of the magnetic properties in the ferromagnetic semiconductor (Ga,Mn)As is possible using the strain induced by a piezoelectric actuator even in the limit of high doping levels and high Curie temperatures, where ... More
Magnetoresistance in Co-hBN-NiFe tunnel junctions enhanced by resonant tunneling through single defects in ultrathin hBN barriersOct 03 2018Hexagonal boron nitride (hBN) is a prototypical high-quality two-dimensional insulator and an ideal material to study tunneling phenomena, as it can be easily integrated in vertical van der Waals devices. For spintronic devices, its potential has been ... More
Manipulation of the magnetic configuration of (Ga,Mn)As nanostructuresAug 11 2009We have studied the magnetic reversal of L-shaped nanostructures fabricated from (Ga,Mn)As. The strain relaxation due to the lithographic patterning results in each arm having a uniaxial magnetic anisotropy. Our analysis confirms that the magnetic reversal ... More
Emergence of the N=16 shell gap in 21ODec 18 2010The spectroscopy of 21O has been investigated using a radioactive 20O beam and the (d,p) reaction in inverse kinematics. The ground and first excited states have been determined to be Jpi=5/2+ and Jpi=1/2+ respectively. Two neutron unbound states were ... More
Infrared-to-violet tunable optical activity in atomic films of GaSe, InSe, and their heterostructuresOct 03 2018Two-dimensional semiconductors - atomic layers of materials with covalent intra-layer bonding and weak (van der Waals or quadrupole) coupling between the layers - are a new class of materials with great potential for optoelectronic applications. Among ... More
Radio-frequency capacitive gate-based sensingJan 29 2018Developing fast, accurate and scalable techniques for quantum state readout is an active area in semiconductor-based quantum computing. Here, we present results on dispersive sensing of silicon corner state quantum dots coupled to lumped-element electrical ... More
Self-limiting growth of two-dimensional palladium between graphene oxide layersJun 07 2019The ability of different materials to display self-limiting growth has recently attracted enormous attention due to the importance of nanoscale materials in applications for catalysis, energy conversion, (opto)electronics, etc. Here, we show that electrochemical ... More
Combining Neutrino Oscillation Experiments with the Feldman-Cousins MethodApr 16 2012Jun 16 2012In this article we describe how two or more experimental results can be combined within the procedure of Feldman and Cousins, to provide combined confidence limits on the physical parameters of interest. We demonstrate the technique by combining the recent ... More
The Electromagnetic Calorimeter for the T2K Near Detector ND280Aug 15 2013Sep 18 2013The T2K experiment studies oscillations of an off-axis muon neutrino beam between the J-PARC accelerator complex and the Super-Kamiokande detector. Special emphasis is placed on measuring the mixing angle theta_13 by observing electron neutrino appearance ... More
Photon detector system timing performance in the DUNE 35-ton prototype liquid argon time projection chamberMar 16 2018Jun 06 2018The 35-ton prototype for the Deep Underground Neutrino Experiment far detector was a single-phase liquid argon time projection chamber with an integrated photon detector system, all situated inside a membrane cryostat. The detector took cosmic-ray data ... More
Indirect to direct gap crossover in two-dimensional InSe revealed by ARPESJan 21 2019Atomically thin films of III-VI post-transition metal chalcogenides (InSe and GaSe) form an interesting class of two-dimensional semiconductor that feature strong variations of their band gap as a function of the number of layers in the crystal [1-4] ... More
Non-Orthogonal Multi-band CAP for Highly Spectrally Efficient VLC SystemsJun 21 2018In this work we propose and experimentally demonstrate a novel non-orthogonal multi-band carrier-less amplitude and phase (NM-CAP) scheme for bandlimited visible light communication systems in order to increase the spectral efficiency. We show that a ... More
Measurement of neutrino and antineutrino oscillations by the T2K experiment including a new additional sample of $ν_e$ interactions at the far detectorJul 04 2017Jul 05 2017The T2K experiment reports an updated analysis of neutrino and antineutrino oscillations in appearance and disappearance channels. A sample of electron neutrino candidates at Super-Kamiokande in which a pion decay has been tagged is added to the four ... More
Measurement of $\barν_μ$ and $ν_μ$ charged current inclusive cross sections and their ratio with the T2K off-axis near detectorJun 13 2017We report a measurement of cross section $\sigma(\nu_{\mu}+{\rm nucleus}\rightarrow\mu^{-}+X)$ and the first measurements of the cross section $\sigma(\bar{\nu}_{\mu}+{\rm nucleus}\rightarrow\mu^{+}+X)$ and their ratio $R(\frac{\sigma(\bar \nu)}{\sigma(\nu)})$ ... More
A new SATIRE-S spectral solar irradiance reconstruction for solar cycles 21--23 and its implications for stratospheric ozoneAug 02 2014We present a revised and extended total and spectral solar irradiance (SSI) reconstruction, which includes a wavelength-dependent uncertainty estimate, spanning the last three solar cycles using the SATIRE-S model. The SSI reconstruction covers wavelengths ... More
On topological spaces and topological groups with certain local countable networksDec 03 2014Being motivated by the study of the space $C_c(X)$ of all continuous real-valued functions on a Tychonoff space $X$ with the compact-open topology, we introduced in [15] the concepts of a $cp$-network and a $cn$-network (at a point $x$) in $X$. In the ... More
Diffeomorphisms of the Klein Bottle and Projective PlaneJan 14 1994We calculate the Riemann curvature tensor and sectional curvature for the Lie group of volume-preserving diffeomorphisms of the Klein bottle and projective plane. In particular, we investigate the sign of the sectional curvature, and find a possible disagreement ... More
Functional determinants on certain domainsJun 30 1995Jul 03 1995Functional determinants on various domains of the sphere and flat space are presented for scalar and spinor fields.
Dark energy and the angular size - redshift diagram for milliarcsecond radio sourcesSep 04 2001May 22 2002We investigate observational constraints on the cosmic equation of state from measurements of angular size for a large sample of milliarcsecond compact radio sources. The results are based on a flat Friedmann-Robertson-Walker (FRW) type models driven ... More
Dark energy and the epoch of galaxy formationJan 30 2001The influence of a dark component on the first epoch of galaxy formation is analysed by using the ages of the three oldest high-redshift galaxies known in the literature. Our results, based on a spatially flat accelerated Universe driven by a "quintessence" ... More
Modelling the redshift-space distortion of galaxy clusteringJul 16 1997We use a set of large, high-resolution cosmological N-body simulations to examine the redshift-space distortions of galaxy clustering on scales of order 10-200h^{-1} Mpc. Galaxy redshift surveys currently in progress will, on completion, allow us to measure ... More
Evidence for the Absence of Gluon Orbital Angular Momentum in the NucleonAug 19 2006Oct 20 2006The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. ... More
Helical relativistic electron beam and THz radiationNov 06 2011A THz laser generation utilizing a helical relativistic electron beam propagating through a strong magnetic field is discussed. The initial amplification rate in this scheme is much stronger than that in the conventional free electron laser. A magnetic ... More
Hard x-ray or gamma ray laser by a dense electron beamOct 23 2011Feb 12 2012A coherent x-ray or gamma ray can be created from a dense electron beam propagating through an intense laser undulator. It is analyzed by using the Landau damping theory which suits better than the conventional linear analysis for the free electron laser, ... More
Leading Order Calculation of Electric Conductivity in Hot Quantum Electrodynamics from Diagrammatic MethodsOct 18 2006Jan 12 2007Using diagrammatic methods, we show how the Ward identity can be used to constrain the ladder kernel in transport coefficient calculations. More specifically, we use the Ward identity to determine the necessary diagrams that must be resummed using an ... More
First Muon-Neutrino Disappearance Study with an Off-Axis BeamJan 06 2012We report a measurement of muon-neutrino disappearance in the T2K experiment. The 295-km muon-neutrino beam from Tokai to Kamioka is the first implementation of the off-axis technique in a long-baseline neutrino oscillation experiment. With data corresponding ... More
Comment on "New Limits on Intrinsic Charm in the Nucleon from Global Analysis of Parton Distributions"Apr 04 2015Jul 15 2015A Comment on the Letter by P. Jimenez-Delgado, T.J. Hobbs, J.T. Londergan, and W. Melnitchouk, Phys. Rev. Lett. 114, 082002 (2015).
The effects of viewing angle on the mass distribution of exoplanetsJul 18 2012We present a mathematical method to statistically decouple the effects of unknown inclination angles on the mass distribution of exoplanets that have been discovered using radial-velocity techniques. The method is based on the distribution of the product ... More
Overcoming the Child Langmuir law via Pondermotive Potential of the intense lasersOct 23 2011The maximum current that could be carried in a vacuum tube is given by the so-called Child Langmuir law. A scheme where this limit could be overcome via the pondermotive potential is proposed. The estimation shows that the limit could be overcome by a ... More
Leading Order Calculation of Shear Viscosity in Hot Quantum Electrodynamics from Diagrammatic MethodsAug 12 2007We compute the shear viscosity at leading order in hot Quantum Electrodynamics. Starting from the Kubo relation for shear viscosity, we use diagrammatic methods to write down the appropriate integral equations for bosonic and fermionic effective vertices. ... More
Remarks on the notion of quantum integrabilityDec 16 2010We discuss the notion of integrability in quantum mechanics. Starting from a review of some definitions commonly used in the literature, we propose a different set of criteria, leading to a classification of models in terms of different integrability ... More
Intraday variability in x-ray selected BL Lacertae objectsSep 12 1997We present a study of the intraday variability behaviour of two samples of x-ray selected BL Lac objects, the EMSS and EXOSAT samples consisting of 22 and 11 sources, respectively. In both samples we were able to detect intraday variability in less than ... More
Cosmological implications of old galaxies at high redshiftsJan 04 2002Old high-$z$ galaxies are important tools for understanding the structure formation problem and may become the key to determine the ultimate fate of the Universe. In this {\it letter}, the inferred ages of the three oldest galaxies at high redshifts reported ... More
Thermodynamics, Spectral Distribution and the Nature of Dark EnergyFeb 11 2004Sep 09 2004Recent astronomical observations suggest that the bulk of energy in the Universe is repulsive and appears like a dark component with negative pressure ($\omega \equiv p_x/\rho_x < 0$). In this work we investigate thermodynamic and statistical properties ... More
Measurements of the T2K neutrino beam properties using the INGRID on-axis near detectorNov 14 2011Precise measurement of neutrino beam direction and intensity was achieved based on a new concept with modularized neutrino detectors. INGRID (Interactive Neutrino GRID) is an on-axis near detector for the T2K long baseline neutrino oscillation experiment. ... More
Double fluctuations on the attractive Hubbard model: ladder approximationJan 05 1997We explore, for the first time, the effect of double fluctuations on both the diagonal and off-diagonal self-energy. We use the T-Matrix equations below $T_c$, developed recently by the Z\"urich group (M.H. Pedersen et al) for the local pair attraction ... More
Ordered Phases and Quantum Criticality in Cubic Heavy Fermion CompoundsMar 06 2014Quantum criticality in cubic heavy fermion compounds remains much less explored than in quasi-two-dimensional systems. However, such materials are needed to broadly test the recently suggested global phase diagram for heavy fermion quantum criticality. ... More
Transport Properties of the One Dimensional Ferromagnetic Kondo Lattice Model : A Qualitative Approach to Oxide ManganitesSep 23 1998The transport properties of the ferromagnetic Kondo lattice model in one dimension are studied via bosonization methods. The antiferromagnetic fluctuations, which normally appear because of the RKKY interactions, are explicitly taken into account as a ... More
Evading the CKM Hierarchy: Intrinsic Charm in B DecaysAug 15 2001Nov 20 2001We show that the presence of intrinsic charm in the hadrons' light-cone wave functions, even at a few percent level, provides new, competitive decay mechanisms for B decays which are nominally CKM-suppressed. For example, the weak decays of the B-meson ... More
Collective Field Theory of the Fractional Quantum Hall Edge State and the Calogero-Sutherland ModelJun 29 1994\noindent Using hydrodynamic collective field theory approach we show that one-particle density matrix of the $\nu=1/m$ fractional quantum Hall edge state interpolates between chiral Luttinger liquid behavior $\langle \psi^{\dagger}(r) \psi(0) \rangle ... More
$N=2$ Topological Yang-Mills Theories and Donaldson's PolynomialsApr 03 1994Sep 09 1994The $N=2$ topological Yang-Mills and holomorphic Yang-Mills theories on simply connected compact K\"{a}hler surfaces with $p_g\geq 1$ are reexamined. The $N=2$ symmetry is clarified in terms of a Dolbeault model of the equivariant cohomology. We realize ... More