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Constraining multiple systems with GAIAApr 26 2012GAIA will provide observations of some multiple asteroid and dwarf systems. These observations are a way to determine and improve the quantification of dynamical parameters, such as the masses and the gravity fields, in these multiple systems. Here we ... More

Compositional characterisation of the Themis familyJan 11 2016Context. It has recently been proposed that the surface composition of icy main-belt asteroids (B-,C-,Cb-,Cg-,P-,and D-types) may be consistent with that of chondritic porous interplanetary dust particles (CPIDPs). Aims. In the light of this new association, ... More

The Spectrum of Pluto, 0.40 - 0.93 $μ$m I. Secular and longitudinal distribution of ices and complex organicsSep 01 2015Context. During the last 30 years the surface of Pluto has been characterized, and its variability has been monitored, through continuous near-infrared spectroscopic observations. But in the visible range only few data are available. Aims. The aim of ... More

Spectral and Spin Measurement of Two Small and Fast-Rotating Near-Earth AsteroidsAug 21 2012In May 2012 two asteroids made near-miss "grazing" passes at distances of a few Earth-radii: 2012 KP24 passed at nine Earth-radii and 2012 KT42 at only three Earth-radii. The latter passed inside the orbital distance of geosynchronous satellites. From ... More

The Compositional Structure of the Asteroid BeltJun 16 2015The past decade has brought major improvements in large-scale asteroid discovery and characterization with over half a million known asteroids and over 100,000 with some measurement of physical characterization. This explosion of data has allowed us to ... More

Multiple and Fast: The Accretion of Ordinary Chondrite Parent BodiesMay 27 2014Although petrologic, chemical and isotopic studies of ordinary chondrites and meteorites in general have largely helped establish a chronology of the earliest events of planetesimal formation and their evolution, there are several questions that cannot ... More

Rotationally Resolved Spectroscopy of Asteroid Pairs: No Spectral Variation Suggests Fission is followed by Settling of DustAug 12 2014We examine the spectral properties of asteroid pairs that were disrupted in the last 2 Myrs to examine whether the site of the fission can be revealed. We studied the possibility that the sub-surface material, perhaps on one hemisphere, has spectral characteristics ... More

Mars Encounters cause fresh surfaces on some near-Earth asteroidsSep 19 2013All airless bodies are subject to the space environment, and spectral differences between asteroids and meteorites suggest many asteroids become weathered on very short (<1My) timescales. The spectra of some asteroids, particularly Q-types, indicate surfaces ... More

Comet 162P/Siding Spring: A Surprisingly Large NucleusAug 17 2006We present an analysis of thermal emission from comet 162P/Siding Spring (P/2004 TU12) measured during its discovery apparition in 2004 December. The comet showed no dust coma at this time, so we have sampled emission from the comet's nucleus. Observations ... More

Ultra-Low Delta-v Objects and the Human Exploration of AsteroidsMay 20 2011Jun 15 2011Missions to near-Earth objects (NEOs) are key destinations in NASA's new "Flexible Path" approach. NEOs are also of interest for science, for the hazards they pose, and for their resources. We emphasize the importance of ultra-low delta-v from LEO to ... More

Near-infrared thermal emission from near-Earth asteroids: Aspect-dependent variabilityNov 10 2016Here we explore a technique for constraining physical properties of near-Earth asteroids (NEAs) based on variability in thermal emission as a function of viewing aspect. We present case studies of the low albedo, near-Earth asteroids (285263) 1998 QE2 ... More

The Mission Accessible Near-Earth Objects Survey (MANOS): first photometric resultsJul 12 2016The Mission Accessible Near-Earth Objects Survey (MANOS) aims to physically characterize sub-km Near-Earth Objects (NEOs). We report first photometric results from the survey which began in August, 2013. Photometric observations were performed using 1 ... More

Similar origin for low- and high-albedo Jovian Trojans and Hilda asteroids ?Jul 25 2014Hilda asteroids and Jupiter Trojans are two low-albedo (p$_{\rm v}$ ~ 0.07) populations for which the Nice model predicts an origin in the primordial Kuiper Belt region. However, recent surveys by WISE and the Spitzer Space Telescope (SST) have revealed ... More

Modeling the Expected Performance of the REgolith X-ray Imaging Spectrometer (REXIS)Oct 12 2014Oct 18 2014OSIRIS-REx is the third spacecraft in the NASA New Frontiers Program and is planned for launch in 2016. OSIRIS-REx will orbit the near-Earth asteroid (101955) Bennu, characterize it, and return a sample of the asteroid's regolith back to Earth. The Regolith ... More

A 2 km-size asteroid challenging the rubble-pile spin barrier - a case for cohesionDec 22 2015The rubble pile spin barrier is an upper limit on the rotation rate of asteroids larger than ~200-300 m. Among thousands of asteroids with diameters larger than ~300 m, only a handful of asteroids are known to rotate faster than 2.0 h, all are in the ... More

Unexpected D-type Interlopers in the Inner Main BeltDec 10 2013Very red featureless asteroids (spectroscopic D-types) are expected to have formed in the outer solar system far from the sun. They comprise the majority of asteroids in the Jupiter Trojan population, and are also commonly found in the outer main belt ... More

Physical characterization and origin of binary near-Earth asteroid (175706) 1996 FG3Mar 21 2012The near-Earth asteroid (NEA) (175706) 1996 FG3 is a particularly interesting spacecraft target: a binary asteroid with a low-DeltaV heliocentric orbit. The orbit of its satellite has provided valuable information about its mass density while its albedo ... More

Observations of "Fresh" and Weathered Surfaces on Asteroid Pairs and Their Implications on the Rotational-Fission MechanismJan 17 2014The rotational-fission of a rubble-pile asteroid can result in an "asteroid pair", two un-bound asteroids sharing similar orbits. This mechanism might exposes material that previously had never have been exposed to the weathering conditions of space. ... More

The Puzzling Detection of X-rays From Pluto by ChandraOct 25 2016Using Chandra ACIS-S, we have obtained imaging Xray spectrophotometry of the Pluto system in support of the New Horizons flyby on 14 July 2015. 174 ksec of observations were obtained on 4 visits in Feb 2014 to Aug 2015. We measured a net signal of 6.8 ... More

The CH4 cycles on Pluto over seasonal and astronomical timescalesMar 05 2019New Horizons observations suggest that CH4 on Pluto has a complex history, involving reservoirs of different composition, thickness and stability controlled by volatile processes occurring on different timescales. In order to interpret these observations, ... More

Modeling glacial flow on and onto Pluto's Sputnik PlanumJun 18 2016Observations of Pluto's surface made by the New Horizons spacecraft indicates present-day nitrogen ice glaciation in and around the basin known as Sputnik Planum. Motivated by these observations, we have developed an evolutionary glacial flow model of ... More

Near-IR spectroscopy of asteroids 21 Lutetia, 89 Julia, 140 Siwa, 2181 Fogelin, and 5480 (1989YK8), potential targets for the Rosetta mission; remote observations campaign on IRTFDec 29 2003In the frame of the international campaign to observe potential target asteroids for the Rosetta mission, remote observations have been carried out between Observatoire de Paris, in Meudon-France, and the NASA Infrared Telescope Facility on Mauna Kea. ... More

Composition of the L5 Mars Trojans: Neighbors, not SiblingsSep 12 2007Mars is the only terrestrial planet known to have Tro jan (co-orbiting) asteroids, with a confirmed population of at least 4 objects. The origin of these objects is not known; while several have orbits that are stable on solar-system timescales, work ... More

Modeling glacial flow on and onto Pluto's Sputnik PlanitiaJun 18 2016Jul 26 2018Observations of Pluto's surface made by the New Horizons spacecraft indicates present-day nitrogen ice glaciation in and around the basin known as Sputnik Planum. Motivated by these observations, we have developed an evolutionary glacial flow model of ... More

Pluto's global surface composition through pixel-by-pixel Hapke modeling of New Horizons Ralph/LEISA dataApr 28 2016On July 14th 2015, NASA's New Horizons mission gave us a first view of the Pluto system. The complex compositional diversity of Pluto's encounter hemisphere was revealed by the Ralph/LEISA infrared spectrometer on board of New Horizons. We present compositional ... More

Early Observations and Analysis of the Type Ia SN 2014J in M82May 15 2014We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and twenty-three NIR spectra were obtained from 10 days before ($-$10d) to 10 days after (+10d) the time of maximum $B$-band brightness. The relative ... More

The small binary asteroid (939) IsbergaNov 04 2014In understanding the composition and internal structure of asteroids, their density is perhaps the most diagnostic quantity. We aim here to characterize the surface composition, mutual orbit, size, mass, and density of the small main-belt binary asteroid ... More

Impact Craters on Pluto and Charon Indicate a Deficit of Small Kuiper Belt ObjectsFeb 27 2019The flyby of Pluto and Charon by the New Horizons spacecraft provided high-resolution images of cratered surfaces embedded in the Kuiper belt, an extensive region of bodies orbiting beyond Neptune. Impact craters on Pluto and Charon were formed by collisions ... More

New Horizons: Anticipated Scientific Investigations at the Pluto SystemSep 26 2007The New Horizons spacecraft will achieve a wide range of measurement objectives at the Pluto system, including color and panchromatic maps, 1.25-2.50 micron spectral images for studying surface compositions, and measurements of Pluto's atmosphere (temperatures, ... More

The compositional diversity of non-Vesta basaltic asteroidsMay 17 2017We present near-infrared (0.78-2.45 {\mu}m) reflectance spectra for nine middle and outer main belt (a > 2.5 AU) basaltic asteroids. Three of these objects are spectrally distinct from all classifications in the Bus-DeMeo system and could represent spectral ... More

Analysis of the First Disk-Resolved Images of Ceres from Ultraviolet Observations with the Hubble Space TelescopeOct 10 2001We present HST Faint Object Camera observations of the asteroid 1 Ceres at near-, mid-, and far-UV wavelengths (lambda = 3636, 2795, and 1621 A, respectively) obtained on 1995 June 25. The disk of Ceres is well-resolved for the first time, at a scale ... More

Olivine-dominated A-type asteroids in the Main Belt: Distribution, Abundance and Relation to FamiliesJan 09 2019Differentiated asteroids are rare in the main asteroid belt despite evidence for ~100 distinct differentiated bodies in the meteorite record. We have sought to understand why so few main-belt asteroids differentiated and where those differentiated bodies ... More

Pluto's global surface composition through pixel-by-pixel Hapke modeling of New Horizons Ralph/LEISA dataApr 28 2016Nov 30 2016On July 14th 2015, NASA's New Horizons mission gave us an unprecedented detailed view of the Pluto system. The complex compositional diversity of Pluto's encounter hemisphere was revealed by the Ralph/LEISA infrared spectrometer on board of New Horizons. ... More

A spectral comparison of (379) Huenna and its satelliteFeb 08 2011We present near-infrared spectral measurements of Themis family asteroid (379) Huenna (D~98 km) and its 6 km satellite using SpeX on the NASA IRTF. The companion was farther than 1.5" from the primary at the time of observations and was approximately ... More

2011 HM102: Discovery of a High-Inclination L5 Neptune Trojan in the Search for a post-Pluto New Horizons TargetOct 16 2012Feb 21 2013We present the discovery of a long-term stable L5 (trailing) Neptune Trojan in data acquired to search for candidate Trans-Neptunian objects for the New Horizons spacecraft to fly by during an extended post-Pluto mission. This Neptune Trojan, 2011 HM102, ... More

Surface Compositions Across Pluto and CharonApr 18 2016The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile ices CH$_4$, CO, and N$_2$, that dominate Pluto's surface, have complicated spatial distributions resulting from sublimation, ... More

Great Expectations: Plans and Predictions for New Horizons Encounter with Kuiper Belt Object 2014 MU69 ('Ultima Thule')Aug 06 2018The New Horizons encounter with the cold classical Kuiper Belt object (KBO) 2014 MU69 (informally named 'Ultima Thule,' hereafter Ultima) on 1 January 2019 will be the first time a spacecraft has ever closely observed one of the free-orbiting small denizens ... More

The REgolith X-Ray Imaging Spectrometer (REXIS) for OSIRIS-REx: Identifying Regional Elemental Enrichment on AsteroidsSep 25 2013The OSIRIS-REx Mission was selected under the NASA New Frontiers program and is scheduled for launch in September of 2016 for a rendezvous with, and collection of a sample from the surface of asteroid Bennu in 2019. 101955 Bennu (previously 1999 RQ36) ... More

The Mission Accessible Near-Earth Objects Survey: Four years of photometrySep 10 2018Over 4.5 years, the Mission Accessible Near-Earth Object Survey (MANOS) assembled 228 Near-Earth Object (NEO) lightcurves. We report rotational lightcurves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, lightcurves with no detected variability ... More

The Small Satellites of Pluto as Observed by New HorizonsApr 18 2016The New Horizons mission has provided resolved measurements of Pluto's moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters of $\approx$40 km for Nix and Hydra and ~10 km for Styx and Kerberos. They are also highly ... More

OSIRIS-REx: Sample Return from Asteroid (101955) BennuFeb 22 2017In May of 2011, NASA selected the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) asteroid sample return mission as the third mission in the New Frontiers program. The other two New Frontiers missions ... More

Formation of Charon's Red Poles From Seasonally Cold-Trapped VolatilesMar 09 2019A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location of ... More

Reorientation of Sputnik Planitia implies a Subsurface Ocean on PlutoMar 13 2019The deep nitrogen-covered Sputnik Planitia (SP; informal name) basin on Pluto is located very close to the longitude of Pluto's tidal axis[1] and may be an impact feature [2], by analogy with other large basins in the solar system[3,4]. Reorientation[5-7] ... More

Pluto's Haze as a Surface MaterialMar 09 2019Pluto's atmospheric haze settles out rapidly compared with geological timescales. It needs to be accounted for as a surface material, distinct from Pluto's icy bedrock and from the volatile ices that migrate via sublimation and condensation on seasonal ... More

A Spectroscopic Comparison of HED Meteorites and V-type Asteroids in the Inner Main BeltMar 12 2010V-type asteroids in the inner Main Belt (a < 2.5 AU) and the HED meteorites are thought to be genetically related to one another as collisional fragments from the surface of the large basaltic asteroid 4 Vesta. We investigate this relationship by comparing ... More

The Geology of Pluto and Charon Through the Eyes of New HorizonsApr 19 2016NASA's New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto's encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick layer of volatile ices that appears to be involved ... More

Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigorMar 13 2019The vast, deep, volatile-ice-filled basin informally named Sputnik Planum is central to Pluto's geological activity[1,2]. Composed of molecular nitrogen, methane, and carbon monoxide ices[3], but dominated by N2-ice, this ice layer is organized into cells ... More

The Design Reference Asteroid for the OSIRIS-REx Mission Target (101955) BennuSep 16 2014The Design Reference Asteroid (DRA) is a compilation of all that is known about the OSIRIS-REx mission target, asteroid (101955) Bennu. It contains our best knowledge of the properties of Bennu based on an extensive observational campaign that began shortly ... More

A White Paper on Pluto Follow On Missions: Background, Rationale, and New Mission RecommendationsAug 22 2018Nov 19 2018The exploration of the binary Pluto-Charon and its small satellites during the New Horizons flyby in 2015 revealed not only widespread geologic and compositional diversity across Pluto, but surprising complexity, a wide range of surface unit ages, evidence ... More

Valence Bond Glass Phase in the Diluted Kagome AntiferromagnetsFeb 27 2010We present a theory for site dilution in the Valence Bond Crystal Phase of the Kagome Lattice Heisenberg Model. The presence of an empty site leads to strong singlet bond across the impurity. It also creates a free spin, which delocalizes inside the unit ... More

The Pluto system: Initial results from its exploration by New HorizonsOct 26 2015The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice ... More

Stable pairs and BPS invariantsNov 25 2007Oct 12 2008We define the BPS invariants of Gopakumar-Vafa in the case of irreducible curve classes on Calabi-Yau 3-folds. The main tools are the theory of stable pairs in the derived category and Behrend's constructible function approach to the virtual class. We ... More

The 3-fold vertex via stable pairsSep 24 2007May 24 2008The theory of stable pairs in the derived category yields an enumerative geometry of curves in 3-folds. We evaluate the equivariant vertex for stable pairs on toric 3-folds in terms of weighted box counting. In the toric Calabi-Yau case, the result simplifies ... More

Stable pairs and BPS invariantsNov 25 2007May 23 2017We define the BPS invariants of Gopakumar-Vafa in the case of irreducible curve classes on Calabi-Yau 3-folds. The main tools are the theory of stable pairs in the derived category and Behrend's constructible function approach to the virtual class. We ... More

Almost closed 1-formsApr 18 2012We construct an algebraic almost closed 1-form with zero scheme not expressible (even locally) as the critical locus of a holomorphic function on a nonsingular variety. The result answers a question of Behrend-Fantechi. We correct here an error in our ... More

Two-magnon Raman scattering in spin-ladder geometries and the ratio of rung and leg exchange constantsApr 27 2000Jul 20 2000We discuss ways in which the ratio of exchange constants along the rungs and legs of a spin-ladder material influences the two-magnon Raman scattering spectra and hence can be determined from it. We show that within the Fleury-Loudon-Elliott approach, ... More

Two-magnon Raman scattering in insulating cuprates: Modifications of the effective Raman operatorMar 14 2000May 24 2000Calculations of Raman scattering intensities in spin 1/2 square-lattice Heisenberg model, using the Fleury-Loudon-Elliott theory, have so far been unable to describe the broad line shape and asymmetry of the two magnon peak found experimentally in the ... More

Covariance Properties of Reflection Equation AlgebrasDec 01 1992The reflection equations (RE) are a consistent extension of the Yang-Baxter equations (YBE) with an addition of one element, the so-called reflection matrix or $K$-matrix. For example, they describe the conditions for factorizable scattering on a half ... More

Curve counting via stable pairs in the derived categoryJul 16 2007May 09 2016For a nonsingular projective 3-fold $X$, we define integer invariants virtually enumerating pairs $(C,D)$ where $C\subset X$ is an embedded curve and $D\subset C$ is a divisor. A virtual class is constructed on the associated moduli space by viewing a ... More

BRST analysis of topologically massive gauge theory: novel observationsApr 07 2011Jul 14 2011A dynamical non-Abelian 2-form gauge theory (with B \wedge F term) is endowed with the "scalar" and "vector" gauge symmetry transformations. In our present endeavor, we exploit the latter gauge symmetry transformations and perform the Becchi-Rouet-Stora-Tyutin ... More

Notes on the proof of the KKV conjectureNov 04 2014May 09 2016The Katz-Klemm-Vafa conjecture expresses the Gromov-Witten theory of K3 surfaces (and K3-fibred 3-folds in fibre classes) in terms of modular forms. Its recent proof gives the first non-toric geometry in dimension greater than 1 where Gromov-Witten theory ... More

13/2 ways of counting curvesNov 07 2011May 09 2016In the past 20 years, compactifications of the families of curves in algebraic varieties X have been studied via stable maps, Hilbert schemes, stable pairs, unramified maps, and stable quotients. Each path leads to a different enumeration of curves. A ... More

Observer dependence of the quasi-local energy and momentum in Schwarzschild space-timeJan 23 2008Sep 03 2008The observer dependence of the quasi-local energy (QLE) and momentum in the Schwarzschild geometry is illustrated. Using the Brown-York prescription, the QLE for families of non-geodesic and geodesic observers penetrating the event horizon is obtained. ... More

Logarithmic rate dependence in deforming granular materialsOct 08 2002Rate-independence for stresses within a granular material is a basic tenet of many models for slow dense granular flows. By contrast, logarithmic rate dependence of stresses is found in solid-on-solid friction, in geological settings, and elsewhere. In ... More

Sextic potential for $γ$-rigid prolate nucleiAug 04 2015The equation of the Bohr-Mottelson Hamiltonian with a sextic oscillator potential is solved for $\gamma$-rigid prolate nuclei. The associated shape phase space is reduced to three variables which are exactly separated. The angular equation has the spherical ... More

Updated study of the quintuple system V994 HerculisApr 05 2016Aims: We present a new updated study of the unique quintuple system of two eclipsing binaries, V994 Her. Methods: Based on new obtained photometric observations, we analysed the period variations of the two eclipsing pairs of V994 Her. Results: We found ... More

An analysis of dynamical suppression of spontaneous emissionSep 04 1998It has been shown recently [see, for example, S.-Y. Zhu and M. O. Scully, Phys. Rev. Lett. {\bf 76}, 388 (1996)] that a dynamical suppression of spontaneous emission can occur in a three-level system when an external field drives transitions between a ... More

Quark confinement and metric fluctuationsAug 23 2009We analyse, by doing very simple calculations, the internal degree of freedom leading to the de Broglie frequency associated to a material particle, as well, the confinement of quarks provided both by the Cornell potential and by the MIT bag model.We ... More

Fluctuations in the Gravitational, Strong and Weak Nuclear Fields through an Effective Harmonic Oscillator ModelDec 10 2001We propose an effective harmonic oscillator model in order to treat the fluctuations of the gravitational, strong and weak nuclear fields. With respect to the gravitational field, first we use the model to estimate its fluctuating strength, necessary ... More

Second RPA and correlated realistic interactionsMay 27 2008We examine the response of closed-shell nuclei using a correlated interaction, derived with the Unitary Correlation Operator Method (UCOM) from the Argonne V18 potential, in second RPA (SRPA) calculations. The same correlated two-body interaction is used ... More

Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell ModelMay 28 2007We propose an importance truncation scheme for the no-core shell model, which enables converged calculations for nuclei well beyond the p-shell. It is based on an a priori measure for the importance of individual basis states constructed by means of many-body ... More

What is Physics: The individual and the universal, and seeing past the noiseMay 09 2016Along with weaving together observations, experiments, and theoretical constructs into a coherent mesh of understanding of the world around us, physics over its past five centuries has continuously refined the base concepts on which the whole framework ... More

Dimensions, nodes and phases in quantum numbersJun 26 2009Students of quantum mechanics encounter discrete quantum numbers in a somewhat incoherent and bewildering number of ways. For each physical system studied, quantum numbers seem to be introduced in its own specific way, some enumerating from 1 and others ... More

The pulsation modes, masses and evolution of luminous red giantsFeb 10 2015The period-luminosity sequences and the multiple periods of luminous red giant stars are examined using the OGLE III catalogue of long-period variables in the Large Magellanic Cloud. It is shown that the period ratios in individual multimode stars are ... More

Dynamical Systems, Stability, and ChaosFeb 23 2007Apr 26 2007In this expository and resources chapter we review selected aspects of the mathematics of dynamical systems, stability, and chaos, within a historical framework that draws together two threads of its early development: celestial mechanics and control ... More

Neutron Star Astronomy with the HSTDec 10 2010Since its launch in 1990, HST has played a leading role in optical studies of isolated neutron stars, both radio-loud pulsars and radio-silent ones, paving the way to follow-up observations performed with 8m-class telescopes, like the VLT, the Gemini, ... More

The HST contribution to neutron star astronomyOct 29 2007While isolated neutron stars (INSs) are among the brightest gamma-ray sources, they are among the faintest ones in the optical, and their study is a challenging task which require the most powerful telescopes. HST has lead neutron star optical astronomy ... More

Multi-wavelength observations of Isolated Neutron StarsJul 03 2012Almost 30 Isolated Neutron Stars (INSs) of different flavours have been identified at optical, ultraviolet, or infrared (UVOIR) wavelengths. Here, I present a short review of the historical background and describe the scientific impact of INS observations ... More

Optical pulsations from isolated neutron starsNov 23 2011Being fast rotating objects, isolated neutron stars (INSs) are obvious targets for high-time resolution observations. With the number of optical/UV/IR INS detections now increased to 24, timing observations become more and more important in INS astrophysics. ... More

The Crab optical and ultraviolet polarimetryFeb 03 2009Polarisation measurements of pulsars and of their pulsar wind nebulae (PWNe) are uniquely able to provide deep insights into the highly magnetised relativistic environment of young, rotation-powered isolated neutron stars (INSs). Besides the radio band, ... More

Muon to electron conversion: The COMET and Mu2e experimentsDec 03 2014I describe the new generation of muon-to-electron conversion experiments, COMET and Mu2e, being constructed to make use of new high power pulsed muon beams a J-PARC and Fermilab respectively. A brief overview of the physics explored by the muon to electron ... More

Chaotic and fractal properties of deterministic diffusion-reaction processesApr 08 1998Jul 10 1998We study the consequences of deterministic chaos for diffusion-controlled reaction. As an example, we analyze a diffusive-reactive deterministic multibaker and a parameter-dependent variation of it. We construct the diffusive and the reactive modes of ... More

Influence of the electric field on edge dislocations in smecticsMay 09 1995The electric field applied perpendicularly to smectic layers breaks the rotational symmetry of the system. Consequently, the elastic energy associated with distortions induced by an edge dislocation diverges logarithmically with the size of the system. ... More

Coherent transport in disordered metals: zero dimensional limitSep 02 2002We consider non-equilibrium transport in disordered conductors. We calculate the interaction correction to the current for a short wire connected to electron reservoirs by resistive interfaces. In the absence of charging effects we find a universal current-voltage-characteristics. ... More

Order and chaos in hydrodynamic BL Her modelsSep 23 2013Many dynamical systems of different complexity, e.g. 1D logistic map, the Lorentz equations, or real phenomena, like turbulent convection, show chaotic behaviour. Despite huge differences, the dynamical scenarios for these systems are strikingly similar: ... More

Non-linear modelling of beat Cepheids: Resonant and non-resonant modelsAug 23 2010The phenomenon of double-periodic Cepheid pulsation is still poorly understood. Recently we rediscussed the problem of modelling the double-periodic pulsation with non-linear hydrocodes. We showed that the published non-resonant double-mode models are ... More

Optomechanics of a Quantum-Degenerate Fermi GasNov 25 2009Feb 09 2010We explore theoretically the optomechanical interaction between a light field and a mechanical mode of ultracold fermionic atoms inside a Fabry-P\'{e}rot cavity. The low-lying phonon mode of the fermionic ensemble is a collective density oscillation associated ... More

Spinons, Solitons and Magnons in One-dimensional Heisenberg-Ising AntiferromagnetsOct 12 1995We calculate the excitation spectra for the one-$d$ Heisenberg-Ising antiferromagnets by expansions around the Ising limit. For $S=1/2$, the calculated expansion coefficients for the spinon-spectra agree term by term with the solution of Johnson and McCoy. ... More

Nilpotent Symmetries of a Diffeomorphism Invariant Theory: BRST ApproachAug 16 2016Within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism, we discuss the full set of proper BRST and anti-BRST transformations for a diffeomorphism invariant theory which is described by the Lagrangian density of a standard bosonic string (proposed ... More

Nilpotent (anti-)BRST symmetry transformations for dynamical non-Abelian 2-form gauge theory: superfield formalismMay 27 2010Sep 30 2010We derive the off-shell nilpotent and absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for the dynamical non-Abelian 2-form gauge theory within the framework of geometrical superfield formalism. We obtain ... More

Superfield Approach To Nilpotent Symmetries For QED From A Single Restriction: An Alternative To The Horizontality ConditionOct 19 2005Aug 04 2006We derive together the exact local, covariant, continuous and off-shell nilpotent Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for the U(1) gauge field (A_\mu), the (anti-)ghost fields ((\bar C)C) and the Dirac fields (\psi, ... More

Superfield Approach to (Non-)local Symmetries for One-Form Abelian Gauge TheoryJun 19 2003Dec 31 2003We exploit the geometrical superfield formalism to derive the local, covariant and continuous Becchi-Rouet-Stora-Tyutin (BRST) symmetry transformations and the non-local, non-covariant and continuous dual-BRST symmetry transformations for the free Abelian ... More

Jacobi Identity for Poisson Brackets: A Concise ProofOct 29 2002Aug 20 2004In view of the recent interest in a short proof of the Jacobi identity for the Poisson-brackets, we provide an alternative simple proof for the same. Our derivation is based on the validity of the Leibnitz rule in the context of dynamical evolution.

Lagrangian formulation of some q-deformed systemsMar 08 2003Sep 19 2003In the framework of Lagrangian formulation, some q-deformed physical systems are considered. The q-deformed Legendre transformation is obtained for the free motion of a non-relativistic particle on a quantum line. This is subsequently exploited to obtain ... More

Gauge Transformations, BRST Cohomology and Wigner's Little GroupDec 19 2002Nov 28 2006We discuss the (dual-)gauge transformations and BRST cohomology for the two (1 + 1)-dimensional (2D) free Abelian one-form and four (3 + 1)-dimensional (4D) free Abelian 2-form gauge theories by exploiting the (co-)BRST symmetries (and their corresponding ... More

Charged Brownian Particle in a Magnetic FieldNov 07 2000We derive explicit forms of Markovian transition probability densities for the velocity space and phase-space Brownian motion of a charged particle in a constant magnetic field.

Predictions in SU(5) Supergravity Grand Unification with Proton Stability and Relic Density ConstraintsFeb 26 1993Apr 14 1993It is shown that in the physically interesting domain of the parameter space of SU(5) supergravity GUT, the Higgs and the Z poles dominate the LSP annihilation. Here the naive analyses on thermal averaging breaks down and formulae are derived which give ... More

A comparison of radio emission from neutron star and black hole X-ray binariesNov 03 1999I compare the properties of radio emission from neutron star and black hole X-ray binaries. In both transient and persistent systems the ratio of X-ray : radio fluxes is comparable for (low field) neutron stars and black holes. It appears that, broadly ... More

New radio observations of Circinus X-1Jul 03 1997New radio observations of the radio-jet X-ray binary Circinus X-1 over nearly an entire 16.6-day orbit are presented. The source continues to undergo radio flaring in the phase interval 0.0 - 0.2 and appears to be brightening since observations in the ... More

Nonlocal Metric Realizations of MONDMar 26 2014I discuss relativistic extensions of MOND in which the metric couples normally to matter. I argue that MOND might be a residual effect from the vacuum polarization of infrared gravitons produced during primordial inflation. If so, MOND corrections to ... More