Results for "J. M. Rathborne"

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Results from the South Pole InfraRed EXplorer TelescopeOct 20 2003The SPIREX telescope, located at the Amundsen-Scott South Pole Station, was a prototype system developed to exploit the excellent conditions for IR observing at the South Pole. Observations over two winter seasons achieved remarkably deep, high-resolution, ... More
Infrared Dark Clouds: precursors to star clustersFeb 10 2006Infrared Dark Clouds (IRDCs) are dense molecular clouds seen as extinction features against the bright mid-infrared Galactic background. Millimeter continuum maps toward 38 IRDCs reveal extended cold dust emission to be associated with each of the IRDCs. ... More
SMA observations of Infrared Dark Clouds: A tale of two coresAug 21 2008We present high-angular resolution sub-millimeter continuum images and molecular line spectra obtained with the SMA toward two massive cores that lie within Infrared Dark Clouds; one actively star-forming (G034.43+00.24 MM1) and the other more quiescent ... More
Dense cores in the Pipe Nebula: An improved core mass functionApr 27 2009In this paper we derive an improved core mass function (CMF) for the Pipe Nebula from a detailed comparison between measurements of visual extinction and molecular-line emission. We have compiled a refined sample of 201 dense cores toward the Pipe Nebula ... More
The Giant Pillars of the Carina NebulaOct 21 2003Results are presented from a multi-wavelength study of the giant pillars within the Carina Nebula. Using near-IR data from 2MASS, mid-IR data from MSX, 843MHz radio continuum maps from the MOST, and molecular line and continuum observations from the SEST, ... More
On the fidelity of the core mass functions derived from dust column density dataJan 27 2009Aims: We examine the recoverability and completeness limits of the dense core mass functions (CMFs) derived for a molecular cloud using extinction data and a core identification scheme based on two-dimensional thresholding. Methods: We performed simulations ... More
The nature of the dense core population in the Pipe Nebula: A survey of NH3, CCS, and HC5N molecular line emissionAug 27 2007Recent extinction studies of the Pipe Nebula (d=130 pc) reveal many cores spanning a range in mass from 0.2 to 20.4 Msun. These dense cores were identified via their high extinction and comprise a starless population in a very early stage of development. ... More
The southern dust pillars of the Carina NebulaAug 31 2001We present preliminary results from a detailed study towards four previously detected bright mid-infrared sources in the southern part of the Carina Nebula: G287.73--0.92, G287.84--0.82, G287.93--0.99 and G288.07--0.80. All of these sources are located ... More
Massive Protostars in the Infrared Dark Cloud MSXDC G034.43+00.24Aug 22 2005We present a multiwavelength study of the infrared dark cloud MSXDC G034.43+00.24. Dust emission, traced by millimeter/submillimeter images obtained with the IRAM, JCMT, and CSO telescopes, reveals three compact cores within this infrared dark cloud with ... More
The dense ring in the Coalsack: the merging of two subsonic flowsSep 11 2008A recent high angular resolution extinction map toward the most opaque molecular globule, Globule 2, in the Coalsack Nebula revealed that it contains a strong central ring of dust column density. This ring represents a region of high density and pressure ... More
Molecular clouds and clumps in the Boston University-Five College Radio Astronomy Observatory Galactic Ring SurveyApr 07 2009The Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS) of 13 CO (1-0) emission covers Galactic longitudes 18 deg < l < 55.7 deg and Galactic latitudes |b| <= 1 deg. Using the SEQUOIA array on the FCRAO 14m ... More
Star and Stellar Cluster Formation: ALMA-SKA SynergiesApr 14 2015Over the next decade, observations conducted with ALMA and the SKA will reveal the process of mass assembly and accretion onto young stars and will be revolutionary for studies of star formation. Here we summarise the capabilities of ALMA and discuss ... More
The Nature of the Dense Core Population in the Pipe Nebula: Thermal Cores Under PressureSep 07 2007In this paper we present the results of a systematic investigation of an entire population of starless dust cores within a single molecular cloud. Analysis of extinction data shows the cores to be dense objects characterized by a narrow range of density. ... More
Some like it cold: molecular emission and effective dust temperatures of dense cores in the Pipe NebulaJun 02 2014(abridged) [...] Methods: In a continued study of the molecular core population of the Pipe Nebula, we present a molecular-line survey of 52 cores. Previous research has shown a variety of different chemical evolutionary stages among the cores. Using ... More
The nature of the dense core population in the pipe nebula: core and cloud kinematics from C18O observationsSep 04 2007We present molecular-line observations of 94 dark cloud cores identified in the Pipe nebula through near-IR extinction mapping. Using the Arizona Radio Observatory 12m telescope, we obtained spectra of these cores in the J=1-0 transition of C18O. We use ... More
Unlocking the Keyhole - H2 and PAH emission from molecular clumps in the Keyhole NebulaOct 08 2000To better understand the environment surrounding CO emission clumps in the Keyhole Nebula, we have made images of the region in H2 1-0 S(1) (2.122 um) emission and polycyclic aromatic hydrocarbon (PAH) emission at 3.29 um. Our results show that the H2 ... More
Photodissociation regions and star formation in the Carina NebulaNov 16 2001We have obtained wide-field thermal infrared (IR) images of the Carina Nebula, using the SPIREX/Abu telescope at the South Pole. Emission from poly-cyclic aromatic hydrocarbons (PAHs) at 3.29um, a tracer of photodissociation regions (PDRs), reveals many ... More
The early stages of star formation in Infrared Dark Clouds: characterizing the core dust propertiesMar 16 2010Identified as extinction features against the bright Galactic mid-infrared background, infrared dark clouds (IRDCs) are thought to harbor the very earliest stages of star and cluster formation. In order to better characterize the properties of their embedded ... More
Dense molecular gas at 12 mm towards Galactic TeV gamma-ray sourcesMay 11 2017The High Energy Stereoscopic System (H.E.S.S.) has revealed many TeV (10 12 eV) gamma-ray sources along the Galactic Plane and around 30 percent of these sources remain unidentified. The morphology and dynamics of dense gas coincident and surrounding ... More
Interferometric Observations of High-Mass Star-Forming Clumps with Unusual N2H+/HCO+ Line RatiosJan 20 2015The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey has detected high-mass star-forming clumps with anomalous N$_2$H$^+$/HCO$^+$(1-0) integrated intensity ratios that are either unusually high ("N$_2$H$^+$ rich") or unusually low ("N$_2$H$^+$ ... More
The RMS Survey: Distribution and properties of a sample of massive young starsAug 18 2010Sep 10 2010The Red MSX Source (RMS) survey has identified a large sample of massive young stellar objects (MYSOs) and ultra compact (UC) HII regions from a sample of ~2000 MSX and 2MASS colour selected sources. Using a recent catalogue of molecular clouds derived ... More
Tracing the Conversion of Gas into Stars in Young Massive Cluster ProgenitorsFeb 12 2015Whilst young massive clusters (YMCs; $M$ $\gtrsim$ 10$^{4}$ M$_{\odot}$, age $\lesssim$ 100 Myr) have been identified in significant numbers, their progenitor gas clouds have eluded detection. Recently, four extreme molecular clouds residing within 200 ... More
Fragmentation in filamentary molecular cloudsDec 21 2015Recent surveys of dust continuum emission at sub-mm wavelengths have shown that filamentary molecular clouds are ubiquitous along the Galactic plane. These structures are inhomogeneous, with over-densities that are sometimes associated with infrared emission ... More
The Molecular Properties of Galactic HII RegionsOct 21 2008We derive the molecular properties for a sample of 301 Galactic HII regions including 123 ultra compact (UC), 105 compact, and 73 diffuse nebulae. We analyze all sources within the BU-FCRAO Galactic Ring Survey (GRS) of 13CO emission known to be HII regions ... More
Comparing Young Massive Clusters and their Progenitor Clouds in the Milky WayFeb 08 2016Young massive clusters (YMCs) have central stellar mass surface densities exceeding $10^{4} M_{\odot} pc^{-2}$. It is currently unknown whether the stars formed at such high (proto)stellar densities. We compile a sample of gas clouds in the Galaxy which ... More
Candidate super star cluster progenitor gas clouds possibly triggered by close passage to Sgr A*Apr 08 2013Super star clusters are the end product of star formation under the most extreme conditions. As such, studying how their final stellar populations are assembled from their natal progenitor gas clouds can provide strong constraints on star formation theories. ... More
Asymmetric Line Profiles in Dense Molecular Clumps Observed in MALT90: Evidence for Global CollapseNov 13 2018Using molecular line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90), we have searched the optically thick \hcop\, line for the "blue asymmetry" spectroscopic signature of infall motion in a large sample of high-mass, dense molecular ... More
G337.342-0.119 (the "Pebble"): A Cold, Dense, High-Mass Molecular Cloud with Unusually Large Linewidths and a Candidate High-Mass Star Cluster ProgenitorNov 14 2018Nov 16 2018Exactly how high-mass star clusters form, especially the young massive clusters (YMCs: age $<100$ Myr; mass $>10^4$ solar masses), remains an open problem, largely because they are so rare that examples of their cold, dense, molecuar progenitors remain ... More
The Formation and Early Evolution of Young Massive ClustersJan 16 2014We review the formation and early evolution of the most massive and dense young stellar clusters, focusing on the role they can play in our understanding of star and planet formation as a whole. Young massive cluster (YMC) progenitor clouds in the Galactic ... More
Linking Dense Gas from the Milky Way to External GalaxiesMar 30 2016Jun 01 2016In a survey of 65 galaxies, Gao & Solomon (2004) found a tight linear relation between the infrared luminosity ($L_{\rm{IR}}$, a proxy for the star formation rate) and the HCN(1-0) luminosity ($L_{\rm{HCN}}$). Wu et al. (2005, 2010) found that this relation ... More
Using young massive star clusters to understand star formation and feedback in high-redshift-like environmentsJan 11 2016The formation environment of stars in massive stellar clusters is similar to the environment of stars forming in galaxies at a redshift of 1 - 3, at the peak star formation rate density of the Universe. As massive clusters are still forming at the present ... More
Chemical Evolution in High-Mass Star-Forming Regions: Results from the MALT90 SurveySep 13 2013The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary stages of dense ... More
Turbulence sets the initial conditions for star formation in high-pressure environmentsSep 03 2014Despite the simplicity of theoretical models of supersonically turbulent, isothermal media, their predictions successfully match the observed gas structure and star formation activity within low-pressure (P/k < 10^5 K cm^-3) molecular clouds in the solar ... More
A cluster in the making: ALMA reveals the initial conditions for high-mass cluster formationJan 29 2015G0.253+0.016 is a molecular clump that appears to be on the verge of forming a high mass, Arches-like cluster. Here we present new ALMA observations of its small-scale (~0.07 pc) 3mm dust continuum and molecular line emission. The data reveal a complex ... More
The link between solenoidal turbulence and slow star formation in G0.253+0.016Sep 28 2016Star formation in the Galactic disc is primarily controlled by gravity, turbulence, and magnetic fields. It is not clear that this also applies to star formation near the Galactic Centre. Here we determine the turbulence and star formation in the CMZ ... More
G0.253+0.016: A centrally condensed, high-mass protoclusterMar 05 2014Despite their importance as stellar nurseries and the building blocks of galaxies, very little is known about the formation of the highest mass clusters. The dense clump G0.253+0.016 represents an example of a clump that may form an Arches-like, high-mass ... More
The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016Sep 19 2016Star formation is primarily controlled by the interplay between gravity, turbulence, and magnetic fields. However, the turbulence and magnetic fields in molecular clouds near the Galactic Center may differ substantially from spiral-arm clouds. Here we ... More
Bipolar HII regions - Morphology and star formation in their vicinity - I - G319.88$+$00.79 and G010.32$-$00.15Jul 01 2015Our goal is to identify bipolar HII regions and to understand their morphology, their evolution, and the role they play in the formation of new generations of stars. We use the Spitzer and Herschel Hi-GAL surveys to identify bipolar HII regions. We search ... More
Absorption Filaments Towards the Massive Clump G0.253+0.016Sep 12 2014ALMA HCO+ observations of the infrared dark cloud G0.253+0.016 located in the Central Molecular Zone of the Galaxy are presented. The 89 GHz emission is area-filling, optically thick, and sub-thermally excited. Two types of filaments are seen in absorption ... More
The Boston University-Five College Radio Astronomy Observatory Galactic Ring SurveyFeb 07 2006The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey is a new survey of Galactic 13CO (1-0) emission. The survey used the SEQUOIA multi pixel array on the Five College Radio Astronomy Observatory 14 m telescope to cover ... More
A hot molecular outflow driven by the ionized jet associated with IRAS 16562-3959May 17 2011We report molecular line observations in the CO J=3$\rightarrow$2, 6$\rightarrow$5 and 7$\rightarrow$6 transitions, made using the Atacama Pathfinder Experiment Telescope (APEX), toward the massive and dense core IRAS 16562$-$3959. This core harbors a ... More
The Millimeter Astronomy Legacy Team 90 GHz Survey (MALT90) and ALMAMar 12 2013ALMA will revolutionize our understanding of star formation within our galaxy, but before we can use ALMA we need to know where to look. The Millimeter Astronomy Legacy Team 90 GHz (MALT90) Survey is a large international project to map the molecular ... More
Characterizing the properties of cluster precursors in the MALT90 surveyNov 29 2016In the Milky Way there are thousands of stellar clusters each harboring from a hundred to a million stars. Although clusters are common, the initial conditions of cluster formation are still not well understood. To determine the processes involved in ... More
Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring SurveyOct 14 2010We derive the physical properties of 580 molecular clouds based on their 12CO and 13CO line emission detected in the University of Massachusetts-Stony Brook (UMSB) and Galactic Ring surveys. We provide a range of values of the physical properties of molecular ... More
A Catalog of MSX Infrared Dark Cloud CandidatesNov 02 2005We use 8.3 um mid-infrared images acquired with the Midcourse Space Experiment satellite to identify and catalog Infrared Dark Clouds (IRDCs) in the first and fourth quadrants of the Galactic plane. Because IRDCs are seen as dark extinction features against ... More
The "Nessie" Nebula: Cluster Formation in a Filamentary Infrared Dark CloudJul 30 2010The "Nessie" Nebula is a filamentary infrared dark cloud (IRDC) with a large aspect ratio of over 150:1 (1.5 degrees x 0.01 degrees, or 80 pc x 0.5 pc at a kinematic distance of 3.1 kpc). Maps of HNC (1-0) emission, a tracer of dense molecular gas, made ... More
Kinematic Distances to Molecular Clouds identified in the Galactic Ring SurveyMay 06 2009Kinematic distances to 750 molecular clouds identified in the 13CO J=1-0 Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (BU-FCRAO GRS) are derived assuming the Clemens rotation curve of the Galaxy. The kinematic distance ... More
Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular cloudsMar 14 2019Young massive clusters (YMCs) are the most compact, high-mass stellar systems still forming at the present day. The precursor clouds to such systems are, however, rare due to their large initial gas mass reservoirs and rapid dispersal timescales due to ... More
Molecular gas kinematics within the central 250 pc of the Milky WayJan 14 2016Feb 10 2016Using spectral-line observations of HNCO, N2H+, and HNC, we investigate the kinematics of dense gas in the central ~250 pc of the Galaxy. We present SCOUSE (Semi-automated multi-COmponent Universal Spectral-line fitting Engine), a line fitting algorithm ... More
Far-Infrared Dust Temperatures and Column Densities of the MALT90 Molecular Clump SampleNov 03 2015We present dust column densities and dust temperatures for $\sim3000$ young high-mass molecular clumps from the Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey, derived from adjusting single temperature dust emission models to the far-infrared ... More
High-mass star-forming cloud G0.38+0.04 in the Galactic Center Dust Ridge contains H2CO and SiO masersOct 21 2015Nov 16 2015We have discovered a new H$_2$CO (formaldehyde) $1_{1,0}-1_{1,1}$ 4.82966 GHz maser in Galactic Center Cloud C, G0.38+0.04. At the time of acceptance, this is the eighth region containing an H$_2$CO maser detected in the Galaxy. Cloud C is one of only ... More
Characterization of the MALT90 Survey and the Mopra Telescope at 90 GHzJun 03 2013Jul 09 2013We characterize the Millimeter Astronomy Legacy Team 90 GHz (MALT90) Survey and the Mopra telescope at 90 GHz. We combine repeated position-switched observations of the source G300.968+01.145 with a map of the same source in order to estimate the pointing ... More
A CH3CN and HCO+ survey towards southern methanol masers associated with star formationDec 23 2005We present the initial results of a 3-mm spectral line survey towards 83 methanol maser selected massive star-forming regions. Here we report observations of the J=5-4 and 6-5 rotational transitions of methyl cyanide (CH3CN) and the J=1-0 transition of ... More
Structure and radial equilibrium of filamentary molecular cloudsMay 22 2013Recent dust continuum surveys have shown that filamentary structures are ubiquitous along the Galactic plane. While the study of their global properties has gained momentum recently, we are still far from fully understanding their origin and stability. ... More
Distributed Low-Mass Star Formation in the IRDC G34.43+00.24Jul 22 2014Sep 02 2014We have used deep near-infrared observations with adaptive optics to discover a distributed population of low-mass protostars within the filamentary Infrared Dark Cloud G34.43+00.24. We use maps of dust emission at multiple wavelengths to determine the ... More
GASKAP -- The Galactic ASKAP SurveyJul 04 2012A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (HI) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder telescope. The survey ... More
MALT90: The Millimetre Astronomy Legacy Team 90 GHz SurveyOct 03 2013The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey aims to characterise the physical and chemical evolution of high-mass star-forming clumps. Exploiting the unique broad frequency range and on-the-fly mapping capabilities of the Australia Telescope ... More
Infall Signatures in a Prestellar Core embedded in the High-Mass 70 $μ$m Dark IRDC G331.372-00.116May 04 2018Using Galactic Plane surveys, we have selected a massive (1200 M$_\odot$), cold (14 K) 3.6-70 $\mu$m dark IRDC G331.372-00.116. This IRDC has the potential to form high-mass stars and, given the absence of current star formation signatures, it seems to ... More
The Millimeter Astronomy Legacy Team 90 GHz (MALT90) Pilot SurveyAug 22 2011We describe a pilot survey conducted with the Mopra 22-m radio telescope in preparation for the Millimeter Astronomy Legacy Team Survey at 90 GHz (MALT90). We identified 182 candidate dense molecular clumps using six different selection criteria and mapped ... More
Fragmentation at the Earliest Phase of Massive Star FormationFeb 04 2009We present 1.3mm continuum and spectral line images of two massive molecular clumps P1 and P2 in the G28.34+0.06 region with the Submillimeter Array. While the two clumps contain masses of 1000 and 880 \msun, respectively, P1 has a luminosity $< 10^2$ ... More
G0.253+0.016: a molecular cloud progenitor of an Arches-like clusterNov 14 2011Young massive clusters (YMCs) with stellar masses of 10^4 - 10^5 Msun and core stellar densities of 10^4 - 10^5 stars per cubic pc are thought to be the `missing link' between open clusters and extreme extragalactic super star clusters and globular clusters. ... More
The Interstellar Medium White PaperJul 02 2013Dec 17 2013The interstellar medium is the engine room for galactic evolution. While much is known about the conditions within the ISM, many important areas regarding the formation and evolution of the various phases of the ISM leading to star formation, and its ... More
Rational streams coalgebraicallyJul 25 2008Sep 19 2008We study rational streams (over a field) from a coalgebraic perspective. Exploiting the finality of the set of streams, we present an elementary and uniform proof of the equivalence of four notions of representability of rational streams: by finite dimensional ... More
Visualising a FuseOct 27 2010Nov 09 2010In this brief article I describe an experiment to illustrate how a fuse works. I have used this as part of lessons for my year 11 classes to demonstrate how an electrical fuse 'blows' when too high a current passes through it.
Trapped surfaces, horizons and exact solutions in higher dimensionsMar 30 2002May 18 2002A very simple criterion to ascertain if (D-2)-surfaces are trapped in arbitrary D-dimensional Lorentzian manifolds is given. The result is purely geometric, independent of the particular gravitational theory, of any field equations or of any other conditions. ... More
Applications of Super-Energy TensorsDec 13 1999In this contribution I intend to give a summary of the new relevant results obtained by using the general superenergy tensors. After a quick review of the definition and properties of these tensors, several of their mathematical and physical applications ... More
Super-energy tensorsJun 21 1999A purely algebraic construction of super-energy tensors for arbitrary fields is presented in any dimensions. These tensors have good mathematical and physical properties, and they can be used in any theory having as basic arena an n-dimensional manifold ... More
(Super)^n-Energy for arbitrary fields and its interchange: Conserved quantitiesMay 17 1999Inspired by classical work of Bel and Robinson, a natural purely algebraic construction of super-energy tensors for arbitrary fields is presented, having good mathematical and physical properties. Remarkably, there appear quantities with mathematical ... More
Remarks on Superenergy TensorsJan 07 1999We define super-energy tensors for arbitrary physical fields, including the gravitational, electromagnetic and massless scalar fields. We also define super-super-energy tensors, and so on. All these tensors satisfy the so-called "Dominant Superenergy ... More
Superenergy tensors and their applicationsFeb 20 2002In Lorentzian manifolds of any dimension the concept of causal tensors is introduced. Causal tensors have positivity properties analogous to the so-called ``dominant energy condition''. Further, it is shown how to build, from ANY given tensor $A$, a new ... More
The global properties of all variety of AGNDec 13 2004Active Galactic Nuclei (AGN) have been a challenging field of research for the past six decades. Nevertheless, many questions still remain unanswered today, regardless of the tremendous theoretical and technological advances. In this brief review I propose ... More
Mobile Phone Faraday CageDec 23 2011A Faraday cage is an interesting physics phenomena where an electromagnetic wave can be excluded from a volume of space by enclosure with an electrically conducting material. The practical application of this in the classroom is to block the signal to ... More
The Wonders of LevitationOct 27 2010I discuss some interesting classroom demonstrations of diamagnetism and how this effect can produce levitation. The possibilities for hands-on demonstrations of diamagnetic and superconducting levitation are discussed. To conclude I discuss some practical ... More
LEP1 vs. Future Colliders: Effective Operators And Extended Gauge GroupJul 24 1992In an effective Lagrangian approach to physics beyond the Standard Model, it has been argued that imposing $SU(2) \times U(1)$ invariance severely restricts the discovery potential of future colliders. We exhibit a possible way out in an extended gauge ... More
Gravitational waves from the collapse and bounce of a stellar core in tensor-scalar gravityNov 16 1999Tensor-scalar theory of gravity allows the generation of gravitational waves from astrophysical sources, like Supernov\ae{}, even in the spherical case. That motivated us to study the collapse of a degenerate stellar core, within tensor-scalar gravity, ... More
The Domino EffectJan 07 2004The physics of a row of toppling dominoes is discussed. In particular the forces between the falling dominoes are analyzed and with this knowledge, the effect of friction has been incorporated. A set of limiting situations is discussed in detail, such ... More
Trace anomalies and the $ΔI = 1/2$ ruleNov 30 2000Trace Anomaly Dominance in weak $K$-decays successfully reproduces the $\Delta I = {1\over 2}$ selection rule results, as observed in $K_S \to \pi\pi, K_L \to \pi\pi\pi, K_S \to \gamma\gamma$ and $K_L \to \pi^0 \gamma\gamma$.
Spin Waves in Canted Phases: An Application to Doped ManganitesNov 29 1999Dec 12 2000We present the effective lagrangian for low energy and momentum spin waves in canted phases at next to leading order in the derivative expansion. The symmetry breaking pattern SU(2) --> 1 of the internal spin group and that of the crystallographic space ... More
Elastic s-wave scattering phase shifts and |Vub| from lattice calculations of form factors for exclusive semileptonic decaysNov 21 2007Omnes dispersion relations make a connection between form factors for exclusive semileptonic decays and phase shifts in the corresponding elastic scattering channels. We describe two applications. In the first, we use lattice form factor calculations ... More
Breakdown of Landau Fermi liquid properties in the $2D$ Boson-Fermion modelDec 07 1995We study the normal state spectral properties of the fermionic excitations in the Boson-Fermion model. The fermionic single particle excitations show a flattening of the dispersion as the Fermi vector ${\bf k}_{_F}$ is approached from below, forshadowing ... More
The Spin Gap in the Context of the Boson-Fermion Model for High $T_c$ SuperconductivityDec 18 1996The issue of the spin gap in the magnetic susceptibility $\chi''(q,\omega)$ in high T_c superconductors is discussed within a scenario of a mixture of localized tightly bound electron pairs in singlet states (bi-polarons) and itinerant electrons. Due ... More
Stochastic MultiresonanceMar 02 1997We present a class of systems for which the signal-to-noise ratio as a function of the noise level may display a multiplicity of maxima. This phenomenon, referred to as stochastic multiresonance, indicates the possibility that periodic signals may be ... More
All tree-level amplitudes in N=4 SYMAug 19 2008Mar 16 2009We give an explicit formula for all tree amplitudes in N=4 SYM, derived by solving the recently presented supersymmetric tree-level recursion relations. The result is given in a compact, manifestly supersymmetric form and we show how to extract from it ... More
Stability of string defects in models of non-Abelian symmetry breakingJul 09 1998Aug 12 1998In this paper we describe a new type of topological defect, called a homilia string, which is stabilized via interactions with the string network. Using analytical and numerical techniques, we investigate the stability and dynamics of homilia strings, ... More
Revealing the extended radio emission from the gamma-ray binary HESS J0632+057Aug 01 2011Sep 04 2011Context. After the detection of a 321-days periodicity in X-rays, HESS J0632+057 can be robustly considered a new member of the selected group of gamma-ray binaries. These sources are known to show extended radio structure at scales of milliarcseconds ... More
O(alpha_s) Spin-Spin Correlations for Top and Bottom Quark Production in e+ e- AnnihilationJun 23 1997Oct 15 1997We present the full O(alpha_s) longitudinal spin-spin correlations for heavy-quark pair production at e+ e- high-energy colliders in closed analytical form. In such reactions, quark and antiquark have strongly correlated spins, and the longitudinal components ... More
Optical Control of Donor Spin Qubits in SiliconJul 28 2015Oct 26 2015We show how to achieve optical, spin-selective transitions from the ground state to excited orbital states of group-V donors (P, As, Sb, Bi) in silicon. We consider two approaches based on either resonant, far-infrared (IR) transitions of the neutral ... More
X-ray properties of active M dwarfs as observed by XMM-NewtonApr 06 2005We present a comparative study of X-ray emission from a sample of active M dwarfs with spectral types \hbox{M3.5 - M4.5} using XMM-Newton observations of two single stars, AD Leonis and EV Lacertae, and two unresolved binary systems, AT Microscopii and ... More
X-ray emission from the remarkable A-type star HR 8799Apr 08 2010We present a Chandra observation of the exceptional planet bearing A5V star HR 8799, more precisely classified as a kA5hF0mA5 star and search for intrinsic X-ray emission. We clearly detect HR 8799 at soft X-ray energies with the ACIS-S detector in a ... More
Shades of Hyperbolicity for HamiltoniansDec 19 2012We prove that a C2 Hamiltonian system H in M is globally hyperbolic if any of the following statements holds: H is robustly topologically stable; H is stably shadowable; H is stably expansive; and H has the stable weak specification property. Moreover, ... More
Diffuse flux of galactic neutrinos and gamma raysOct 08 2016We calculate the fluxes of neutrinos and gamma rays from interactions of cosmic rays with interstellar matter in our galaxy. We use EPOS-LHC, SIBYLL and GHEISHA to obtain the yield of these particles in proton, helium and iron collisions at kinetic energies ... More
How to separate the low amplitude delta Scuti variation from the instrumental ones in CoRoT data?Apr 01 2016Rich regular frequency patterns were found in the Fourier spectra of low-amplitude delta Scuti stars observed by CoRoT satellite (see Papar\'o et al. 2016a,b). The CoRoT observations are, however, influenced by the disturbing effect of the South Atlantic ... More
Classical information capacity of a class of quantum channelsDec 16 2004Apr 14 2005We consider the additivity of the minimal output entropy and the classical information capacity of a class of quantum channels. For this class of channels the norm of the output is maximized for the output being a normalized projection. We prove the additivity ... More
Breathers in the weakly coupled topological discrete sine-Gordon systemFeb 19 1998Jul 06 1998Existence of breather (spatially localized, time periodic, oscillatory) solutions of the topological discrete sine-Gordon (TDSG) system, in the regime of weak coupling, is proved. The novelty of this result is that, unlike the systems previously considered ... More
Good rotationsMay 20 1998Numerical integrations in celestial mechanics often involve the repeated computation of a rotation with a constant angle. A direct evaluation of these rotations yields a linear drift of the distance to the origin. This is due to roundoff in the representation ... More
Stochastic modelling of dynamical systems with several attractorsJun 19 2017The usual Langevin approach to describe systems driven by noise fails to describe the long time behavior of systems with multiple attractors. The solution of the associated linear Fokker-Planck equation is always unique, even though it might show one ... More
Theory of Electric Field-Induced Photoluminescence Quenching in Disordered Molecular SolidsFeb 12 1998The dynamics of excitons in disordered molecular solids is studied theoretically, taking into account migration between different sites, recombination, and dissociation into free charge carriers in the presence of an electric field. The theory is applied ... More
The Adsorption of H2O on TiO2 and SnO2(110) Studied by First-Principles CalculationsAug 24 1995First-principles calculations based on density functional theory and the pseudopotential method have been used to investigate the energetics of H$_2$O adsorption on the (110) surface of TiO$_2$ and SnO$_2$. Full relaxation of all atomic positions is performed ... More
Domino MagnificationJan 03 2013Jan 28 2013The conditions are investigated under which a row of increasing dominoes is able to keep tumbling over. The analysis is restricted to the simplest case of frictionless dominoes that only can topple not slide. The model is scale invariant, i.e. dominoes ... More
Continuum Double Exchange ModelOct 29 1998Jun 18 1999We present a continuum model for doped manganites which consist of two species of quantum spin 1/2 fermions interacting with classical spin fields. The phase structure at zero temperature turns out to be considerably rich: antiferromagnetic insulator, ... More