Results for "William J. Fischer"

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The WISE Census of Young Stellar Objects in Canis MajorOct 20 2015While searches for young stellar objects (YSOs) with the Spitzer Space Telescope focused on known molecular clouds, photometry from the Wide-field Infrared Survey Explorer (WISE) can be used to extend the search to the entire sky. As a precursor to more ... More
Constraining the Rate of Protostellar Accretion Outbursts in the Orion Molecular CloudsJan 23 2019Outbursts due to dramatic increases in the mass accretion rate are the most extreme type of variability in young stellar objects. We searched for outbursts among 319 protostars in the Orion molecular clouds by comparing 3.6, 4.5, and 24 micron photometry ... More
Origins of the H, He I, and Ca II Line Emission in Classical T Tauri StarsOct 15 2010We perform local excitation calculations to obtain line opacities and emissivity ratios and compare them with observed properties of H, He I, O I, Ca II, and Na I lines to determine the density, temperature, and photon ionization rate. We find that UV ... More
Bethe-Salpeter equations: mesons beyond the rainbow-ladder truncationDec 18 2009We investigate masses of light mesons from a coupled system of Dyson--Schwinger (DSE) and Bethe--Salpeter equations (BSE), taking into account dominant non-Abelian, sub-leading Abelian, and dominant pion cloud contributions to the dressed quark-gluon ... More
Baby steps beyond rainbow-ladderMay 15 2009We discuss the impact of including corrections beyond single gluon exchange in light mesons within the nonperturbative framework of Dyson-Schwinger equations (DSE) and Bethe-Salpeter equations (BSE). We do this by considering unquenching effects in the ... More
Pion-cloud effects in the BSE description of mesonsDec 08 2008We investigate the effect of including hadronic resonance contributions in the description of light quarks and mesons. To this end we take into account the back-coupling of the pion onto the quark propagator within the non-perturbative continuum framework ... More
Discovery of a Population of Bulgeless Galaxies with Extremely Red Mid-IR Colors: Obscured AGN Activity in the Low Mass Regime?Jan 21 2014In contrast to massive, bulge hosting galaxies, very few supermassive black holes (SMBHs) are known in either low mass, or bulgeless galaxies. Such a population could provide clues to the origins of SMBHs and to secular pathways for their growth. Using ... More
A WISE Census of Young Stellar Objects in Canis MajorJun 06 2016With the Wide-Field Infrared Survey Explorer (WISE), we searched for young stellar objects (YSOs) in a 100 deg^2 region centered on the lightly studied Canis Major star forming region. Applying stringent magnitude cuts to exclude the majority of extragalactic ... More
Hadronic light-by-light scattering in the muon g-2: a Dyson-Schwinger equation approachDec 17 2010Apr 15 2011We determine the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon using the framework of Dyson-Schwinger and Bethe-Salpeter equations of QCD. Our result for the pseudoscalar ($\pi^0, \eta, \eta'$) meson exchange ... More
Modeling T Tauri Winds from He I 10830 ProfilesNov 17 2006The high opacity of He I 10830 makes it an exceptionally sensitive probe of the inner wind geometry of accreting T Tauri stars. In this line blueshifted absorption below the continuum results from simple scattering of stellar photons, a situation which ... More
Mid- and Far-Infrared ISO Limits on Dust Disks around Millisecond PulsarsMay 18 2004We report 60 and 90 micron observations of 7 millisecond pulsars with ISO. The pulsar PSR B1257+12 is orbited by three planets, and other millisecond pulsars may be orbited by dust disks that represent planets that failed to form or their residue. We ... More
Light mesons in QCD and unquenching effects from the 3PI effective actionDec 01 2015Feb 08 2016We investigate the impact of unquenching effects on QCD Green's functions, in the form of quark-loop contributions to both the gluon propagator and three-gluon vertex, in a three-loop inspired truncation of the three-particle irreducible (3PI) effective ... More
Non-contact interactions and the hadronic light-by-light contribution to the muon g-2Apr 16 2013We summarise recent results for the quark loop part of the light-by-light scattering contribution to the muons anomalous magnetic moment. In particular we focus on the impact of a momentum dependent quark and quark-photon vertex. We compare the Dyson-Schwinger ... More
Hadronic contribution to the muon g-2: a Dyson-Schwinger perspectiveNov 03 2011We summarize our results for hadronic contributions to the anomalous magnetic moment of the muon ($a_\mu$), the one from hadronic vacuum-polarisation (HVP) and the light-by-light scattering contribution (LBL), obtained from the Dyson-Schwinger equations ... More
On Gribov's supercriticality picture of quark confinementJul 22 2008Nov 25 2008Some years ago Gribov developed the so-called supercritical light quark confinement scenario. Based on physical arguments he conjectured a drastic change in the analytical properties of the quark propagator when the back-reaction of Goldstone bosons (pions) ... More
Spectra of heavy mesons in the Bethe-Salpeter approachSep 17 2014Jan 30 2015We present a calculation of the spectrum of charmonia, bottomonia and B_c-meson states with `ordinary' and exotic quantum numbers. We discuss the merits and limitations of a rainbow-ladder truncation of Dyson-Schwinger and Bethe-Salpeter equations and ... More
A fresh look at hadronic light-by-light scattering in the muon g-2 with the Dyson-Schwinger approachSep 27 2010Feb 04 2011We present first results for the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon a_{\mu} in the framework of Dyson-Schwinger and Bethe-Salpeter equations. We determine the quark loop and pseudoscalar ({\pi}^0, ... More
The role of vector meson dominance and running masses in the hadronic contributions to the muon $g-2$Feb 21 2013We summarize our recent results for the quark loop part of the light-by-light scattering contribution as well as the hadronic vacuum polarisation contributions to the anomalous magnetic moment of the muon. In particular we focus on the role played by ... More
The role of momentum dependent dressing functions and vector meson dominance in hadronic light-by-light contributions to the muon g-2Oct 05 2012Oct 23 2012We present a refined calculation of the quark-loop contribution to hadronic light-by-light scatter- ing that focuses upon the impact of the transverse components of the quark-photon vertex. These structures are compared and contrasted with those found ... More
Volume behaviour of quark condensate, pion mass and decay constant from Dyson-Schwinger equationsDec 18 2009May 03 2010We solve the coupled system of Dyson-Schwinger and Bethe-Salpeter equations for the quark propagator and the pion Bethe-Salpeter amplitude on a finite volume. To this end we use a truncation scheme that includes pion cloud effects in the quark propagator ... More
U_A(1) anomaly and eta' mass from an infrared singular quark-gluon vertexApr 22 2008Sep 08 2008The $U_A(1)$ problem of QCD is inevitably tied to the infrared behaviour of quarks and gluons with its most visible effect being the $\eta^\prime$ mass. A dimensional argument of Kogut and Susskind showed that the mixing of the pseudoscalar flavour-singlet ... More
Regge behaviour within the Bethe-Salpeter approachDec 17 2014We present a calculation of the spectrum of light and heavy quark bound states in the rainbow-ladder truncation of Dyson-Schwinger/Bethe-Salpeter equations. By extending the formalism include the case of total angular momentum J=3, we are able to explore ... More
The Impact of Stellar Populations on the Dynamics of Merger RemnantsAug 21 2009Many studies and simulations suggest gas-rich mergers do not contribute significantly to the overall star-formation rate and total mass function of galaxies. The velocity dispersions (sigma) of Luminous & Ultraluminous Infrared Galaxies measured using ... More
About Learning in Recurrent Bistable Gradient NetworksAug 29 2016Recurrent Bistable Gradient Networks are attractor based neural networks characterized by bistable dynamics of each single neuron. Coupled together using linear interaction determined by the interconnection weights, these networks do not suffer from spurious ... More
Definable TowersNov 21 2018We study the definability of maximal towers and of inextendible linearly ordered towers (ilt's), a notion that is more general than that of a maximal tower. We show that there is, in the constructible universe, a $\Pi^1_1$ definable maximal tower that ... More
Mass spectra and Regge trajectories of light mesons in the Bethe-Salpeter approachJun 17 2014Aug 07 2014We extend the calculation of relativistic bound-states of a fermion anti-fermion pair in the Bethe-Salpeter formalism to the case of total angular momentum $J=3$. Together with results for $J \le 2$ this allows for the investigation of Regge trajectories ... More
Measurement of the Mass Profile of Abell 1689Apr 01 1995Apr 03 1995In this letter we present calibrated mass and light profiles of the rich cluster of galaxies Abell 1689 out to 1 $h^{-1}$ Mpc from the center. The high surface density of faint blue galaxies at high redshift, selected by their low surface brightness, ... More
Propagators and Matrix Basis on Noncommutative Minkowski SpaceJun 30 2011Dec 09 2011We describe an analytic continuation of the Euclidean Grosse-Wulkenhaar and LSZ models which defines a one-parameter family of duality covariant noncommutative field theories interpolating between Euclidean and Minkowski space versions of these models, ... More
Incentives Don't Solve Blockchain's ProblemsMay 12 2019A blockchain faces two fundamental challenges. It must motivate users to maintain the system while preventing a minority of these users from colluding and gaining disproportionate control. Many popular public blockchains use monetary incentives to encourage ... More
Methanol and its relation to the water snowline in the disk around the young outbursting star V883 OriAug 24 2018We report the detection of methanol in the disk around the young outbursting star V883 Ori with the Atacama Large Millimeter/submillimeter Array (ALMA). Four transitions are observed with upper level energies ranging between 115 and 459 K. The emission ... More
Herschel Observations of Protoplanetary Disks in Lynds 1641Jun 18 2018We analyze Herschel Space Observatory observations of 104 young stellar objects with protoplanetary disks in the ~1.5 Myr star-forming region Lynds 1641 (L1641) within the Orion A Molecular Cloud. We present spectral energy distributions from the optical ... More
Characterizing the Youngest Herschel-detected Protostars I. Envelope Structure Revealed by CARMA Dust Continuum ObservationsNov 04 2014We present CARMA 2.9 mm dust continuum emission observations of a sample of 14 Herschel-detected Class 0 protostars in the Orion A and B molecular clouds, drawn from the PACS Bright Red Sources (PBRS) sample (Stutz et al.). These objects are characterized ... More
UV/IR duality in noncommutative quantum field theoryJan 21 2010Jun 16 2010We review the construction of renormalizable noncommutative euclidean phi(4)-theories based on the UV/IR duality covariant modification of the standard field theory, and how the formalism can be extended to scalar field theories defined on noncommutative ... More
On the asymptotic nature of first order mean field gamesMar 08 2019For a class of finite horizon first order mean field games and associated N-player games, we give a simple proof of convergence of symmetric N-player Nash equilibria in distributed open-loop strategies to solutions of the mean field game in Lagrangian ... More
Results from HOPS: A Multiwavelength Census of Orion ProtostarsDec 05 2012Surveys with the Spitzer and Herschel space observatories are now enabling the discovery and characterization of large samples of protostars in nearby molecular clouds, providing the observational basis for a detailed understanding of star formation in ... More
The Mid-Infrared Evolution of the FU Orionis DiskSep 06 2016We present new SOFIA-FORCAST observations obtained in Feburary 2016 of the archetypal outbursting low mass young stellar object FU Orionis, and compare the continuum, solid state, and gas properties with mid-IR data obtained at the same wavelengths in ... More
HST Scattered Light Imaging and Modeling of the Edge-on Protoplanetary Disk ESO-H$α$ 569Nov 09 2017We present new HST ACS observations and detailed models for a recently discovered edge-on protoplanetary disk around ESO H$\alpha$ 569 (a low-mass T Tauri star in the Cha I star forming region). Using radiative transfer models we probe the distribution ... More
Single pseudoscalar meson pole and pion box contributions to the anomalous magnetic moment of the muonMar 26 2019We present results for single pseudoscalar meson pole contributions and pion box contributions to the hadronic light-by-light (LBL) correction of the muon's anomalous magnetic moment. We follow the recently developed dispersive approach to LBL, where ... More
Characterizing the Youngest Herschel-detected Protostars II. Molecular Outflows from the Millimeter and the Far-infraredJul 04 2016We present CARMA CO (J=1-0) observations and Herschel PACS spectroscopy, characterizing the outflow properties toward extremely young and deeply embedded protostars in the Orion molecular clouds. The sample comprises a subset of the Orion protostars known ... More
The muon g-2: Dyson-Schwinger status on hadronic light-by-light scatteringNov 28 2014Dec 17 2014We give a status report on the hadronic light-by-light scattering contribution to the muon's anomalous magnetic moment from the Dyson-Schwinger approach. We discuss novel, model-independent properties of the light-by-light amplitude: we give its covariant ... More
F, G, K, M Spectral Standards in the Y Band (0.95-1.11 um)Nov 10 2009Jan 27 2010We take advantage of good atmospheric transparency and the availability of high quality instrumentation in the 1 um near-infrared atmospheric window to present a grid of F, G, K, and M spectral standards observed at high spectral resolution (R ~ 25,000). ... More
Probing T Tauri Accretion and Outflow with 1 Micron SpectroscopyApr 01 2006In a high dispersion 1 micron survey of 39 classical T Tauri stars veiling is detected in 80%, and He I 10830 and Pgamma line emission in 97% of the stars. On average, the 1 micron veiling exceeds the level expected from previously identified sources ... More
Electromagnetic decays of the neutral pion investigated in the Dyson-Schwinger formalismOct 23 2017Oct 30 2017We summarize recent work in determining the transition form factor (TFF) of the neutral pion ($\pi^0 \to \gamma^*\gamma^*$), by solving the non-perturbative Dyson-Schwinger and Bethe-Salpeter equations. We first study the transition form factor, followed ... More
Redshifted Absorption at He I 10830 as a Probe of the Accretion Geometry of T Tauri StarsJul 16 2008We probe the geometry of magnetospheric accretion in classical T Tauri stars by modeling red absorption at He I 10830 via scattering of the stellar and veiling continua. Under the assumptions that the accretion flow is an azimuthally symmetric dipole ... More
On the large-Q^2 behavior of the pion transition form factorApr 19 2017Nov 15 2017We study the transition of non-perturbative to perturbative QCD in situations with possible violations of scaling limits. To this end we consider the singly- and doubly-virtual pion transition form factor $\pi^0\to\gamma\gamma$ at all momentum scales ... More
Quark Condensates: Flavour DependenceMar 23 2007We determine the q-bar q condensate for quark masses from zero up to that of the strange quark within a phenomenologically successful modelling of continuum QCD by solving the quark Schwinger-Dyson equation. The existence of multiple solutions to this ... More
${\bar {q}}q$ condensate for light quarks beyond the chiral limitDec 06 2006We determine the ${\bar{q}}q$ condensate for quark masses from zero up to that of the strange quark within a phenomenologically successful modelling of continuum QCD by solving the quark Schwinger-Dyson equation. The existence of multiple solutions to ... More
Characterizing the IYJ Excess Continuum Emission in T Tauri StarsJan 24 2011We present the first characterization of the excess continuum emission of accreting T Tauri stars between optical and near-infrared wavelengths. With nearly simultaneous spectra from 0.48 to 2.4 microns acquired with HIRES and NIRSPEC on Keck and SpeX ... More
Electromagnetic decays of the neutral pionApr 20 2017May 08 2017We complement studies of the neutral pion transition form factor pi^0 --> gamma^(*) gamma^(*) with calculations for the electromagnetic decay widths of the processes pi^0 --> e^+ e^-, pi^0 --> e^+ e^- gamma and pi^0 --> e^+ e^- e^+ e^-. Their common feature ... More
Effects of Anisotropy in QED3 from Dyson-Schwinger equations in a boxMar 08 2011Jun 29 2011We investigate the effect of anisotropies in the fermion velocities of 2+1 dimensional QED on the critical number N_f^c of fermions for dynamical mass generation. Our framework are the Dyson-Schwinger equations for the gauge boson and fermion propagators ... More
Analysis of Rapidity Gap Cuts in Diffractive DISMay 31 1999The requirement of a large pseudo-rapidity gap to select diffractive DIS events at HERA restricts the kinematically accessible region of phase space for a significant range of $Q^2$, $\beta$ and $\xpom$. Consequences of this include a breakdown of $\xpom$-factorization ... More
On an asymptotic estimate of the $n$-loop correction in perturbative QCDOct 15 1992A recently proposed method of estimating the asymptotic behaviour of QCD perturbation theory coefficients is critically reviewed and shown to contain numerous invalid mathematical operations and unsubstantiated assumptions. We discuss in detail why this ... More
Evolution of Mass Outflow in ProtostarsNov 16 2015We have surveyed 84 Class 0, Class I, and flat-spectrum protostars in mid-infrared [Si II], [Fe II] and [S I] line emission, and 11 of these in far-infrared [O I] emission. We use the results to derive their mass outflow rates. Thereby we observe a strong ... More
$T$-odd correlations in polarized top quark decays in the sequential decay $t(\uparrow) \to X_b+W^+(\to \ell^+ + ν_\ell)$ and in the quasi three-body decay $t(\uparrow) \to X_b+ \ell^+ + ν_\ell$Feb 07 2018We identify the $T$-odd structure functions that appear in the description of polarized top quark decays in the sequential decay $t(\uparrow) \to X_b+W^+(\to \ell^+ + \nu_\ell)$ (two structure functions) and the quasi three-body decay $t(\uparrow) \to ... More
Comparing PyMorph and SDSS photometry. I. Background sky and model fitting effectsFeb 27 2017A number of recent estimates of the total luminosities of galaxies in the SDSS are significantly larger than those reported by the SDSS pipeline. This is because of a combination of three effects: one is simply a matter of defining the scale out to which ... More
Studying pion effects on the chiral phase transitionNov 18 2008We investigate the chiral phase transition at finite temperatures and zero chemical potential with Dyson-Schwinger equations. Our truncation for the quark-gluon interaction includes mesonic degrees of freedom, which allows us to study the impact of the ... More
Charge separation in photosynthesis via a spin exchange coupling mechanismAug 05 1997A new mechanism for the primary photoinduced charge separation in photosynthesis is proposed. It involves as real intermediate between the excited special pair state P* and the primary charge separated state P+HL- a trip-trip-singlet PTBLT, which consists ... More
$T$-odd correlations in polarized top quark decays in the sequential decay $t(\uparrow) \to X_b+W^+(\to \ell^+ + ν_\ell)$ and in the quasi three-body decay $t(\uparrow) \to X_b+ \ell^+ + ν_\ell$Feb 07 2018May 03 2018We identify the $T$-odd structure functions that appear in the description of polarized top quark decays in the sequential decay $t(\uparrow) \to X_b+W^+(\to \ell^+ + \nu_\ell)$ (two structure functions) and the quasi-three-body decay $t(\uparrow) \to ... More
HOPS 383: An Outbursting Class 0 Protostar in OrionJan 02 2015Jan 06 2015We report the dramatic mid-infrared brightening between 2004 and 2006 of HOPS 383, a deeply embedded protostar adjacent to NGC 1977 in Orion. By 2008, the source became a factor of 35 brighter at 24 microns with a brightness increase also apparent at ... More
The Herschel Orion Protostar Survey: Luminosity and Envelope EvolutionApr 19 2017The Herschel Orion Protostar Survey obtained well-sampled 1.2 - 870 micron spectral energy distributions (SEDs) of over 300 protostars in the Orion molecular clouds, home to most of the young stellar objects (YSOs) in the nearest 500 pc. We plot the bolometric ... More
Interpretation of a low-lying excited state of the reaction center of Rb.sphaeroides as a double tripletFeb 13 1997The recently observed transient absorption of the lowest excited state of the special pair P* at 2710 cm-1 is assigned as a singlet which arises from the coupling of the two lowest triplets from the two dimer halves. INDO calculations are used to predict ... More
Reconstructing Neural Parameters and Synapses of arbitrary interconnected Neurons from their Simulated Spiking ActivityAug 22 2016To understand the behavior of a neural circuit it is a presupposition that we have a model of the dynamical system describing this circuit. This model is determined by several parameters, including not only the synaptic weights, but also the parameters ... More
The structure of fluid trifluoromethane and methylfluorideJun 09 2000We present hard X-ray and neutron diffraction measurements on the polar fluorocarbons HCF3 and H3CF under supercritical conditions and for a range of molecular densities spanning about a factor of ten. The Levesque-Weiss-Reatto inversion scheme has been ... More
The Evolution of Protostars: Insights from Ten Years of Infrared Surveys with Spitzer and HerschelJan 08 2014Jan 10 2014Stars form from the gravitational collapse of dense molecular cloud cores. In the protostellar phase, mass accretes from the core onto a protostar, likely through an accretion disk, and it is during this phase that the initial masses of stars and the ... More
Multiwavelength Observations of V2775 Ori, an Outbursting Protostar in L 1641: Exploring the Edge of the FU Orionis RegimeJul 10 2012Individual outbursting young stars are important laboratories for studying the physics of episodic accretion and the extent to which this phenomenon can explain the luminosity distribution of protostars. We present new and archival data for V2775 Ori ... More
A Herschel and APEX Census of the Reddest Sources in Orion: Searching for the Youngest ProtostarsFeb 05 2013We perform a census of the reddest, and potentially youngest, protostars in the Orion molecular clouds using data obtained with the PACS instrument onboard the Herschel Space Observatory and the LABOCA and SABOCA instruments on APEX as part of the Herschel ... More
A Spitzer-IRS Detection of Crystalline Silicates in a Protostellar EnvelopeApr 22 2011We present the Spitzer Space Telescope Infrared Spectrograph spectrum of the Orion A protostar HOPS-68. The mid-infrared spectrum reveals crystalline substructure at 11.1, 16.1, 18.8, 23.6, 27.9, and 33.6 microns superimposed on the broad 9.7 and 18 micron ... More
HOPS 136: An Edge-On Orion Protostar Near the End of Envelope InfallDec 20 2013Edge-on protostars are valuable for understanding the disk and envelope properties of embedded young stellar objects, since the disk, envelope, and envelope cavities are all distinctly visible in resolved images and well constrained in modeling. Comparing ... More
Identifying Young Stellar Objects in the Outer Galaxy: l = 224 deg Region in Canis MajorNov 29 2018We study a very young star-forming region in the outer Galaxy that is the most concentrated source of outflows in the Spitzer Space Telescope GLIMPSE360 survey. This region, dubbed CMa-l224, is located in the Canis Major OB1 association. CMa-l224 is relatively ... More
Kepler-424 b: A "Lonely" Hot Jupiter That Found A CompanionSep 29 2014Hot Jupiter systems provide unique observational constraints for migration models in multiple systems and binaries. We report on the discovery of the Kepler-424 (KOI-214) two-planet system, which consists of a transiting hot Jupiter (Kepler-424b) in a ... More
Old, Rich, and Eccentric: Two Jovian Planets Orbiting Evolved Metal-Rich StarsApr 17 2009Jun 20 2009We present radial velocity measurements of two stars observed as part of the Lick Subgiants Planet Search and the Keck N2K survey. Variations in the radial velocities of both stars reveal the presence of Jupiter-mass exoplanets in highly eccentric orbits. ... More
The Atacama Large Aperture Submillimeter Telescope (AtLAST)Jul 10 2019The sub-mm sky is a unique window for probing the architecture of the Universe and structures within it. From the discovery of dusty sub-mm galaxies, to the ringed nature of protostellar disks, our understanding of the formation, destruction, and evolution ... More
Hierarchical On-Surface Synthesis of Deterministic Graphene Nanoribbon HeterojunctionsNov 15 2017Bottom-up graphene nanoribbon (GNR) heterojunctions are nanoscale strips of graphene whose electronic structure abruptly changes across a covalently bonded interface. Their rational design offers opportunities for profound technological advancements enabled ... More
Planet Hunters: A Transiting Circumbinary Planet in a Quadruple Star SystemOct 12 2012Mar 22 2013We report the discovery and confirmation of a transiting circumbinary planet (PH1b) around KIC 4862625, an eclipsing binary in the Kepler field. The planet was discovered by volunteers searching the first six Quarters of publicly available Kepler data ... More
Towards Understanding the Predictability of Stock Markets from the Perspective of Computational ComplexityOct 14 2000Oct 17 2000This paper initiates a study into the century-old issue of market predictability from the perspective of computational complexity. We develop a simple agent-based model for a stock market where the agents are traders equipped with simple trading strategies, ... More
Baryons as relativistic three-quark bound statesJun 30 2016Jul 22 2016We review the spectrum and electromagnetic properties of baryons described as relativistic three-quark bound states within QCD. The composite nature of baryons results in a rich excitation spectrum, whilst leading to highly non-trivial structural properties ... More
On the quark-gluon vertex at non-vanishing temperatureMay 15 2018We perform a semi-perturbative calculation of the quark-gluon vertex inspired from the three-loop expanded 3PI effective action and investigate the relative strengths of the chirally symmetric/broken tensor structures below and above the crossover.
Interpreting Near Infrared Hydrogen Line Ratios in T Tauri StarsSep 17 2013Sep 19 2013In accreting young stars one of the prominent spectral features in the near infrared is the Paschen and Brackett series in emission. We examine hydrogen line ratios for 16 classical T Tauri stars from SpeX spectra and and assess the trends with veiling ... More
On propagators and three-point functions in Landau gauge QCD and QCD-like theoriesMay 28 2014Recent progress in our studies of propagators and three-point functions in Landau gauge for QCD and QCD-like theories is presented. Special emphasis is put on the properties of the three-gluon vertex and the quark-gluon vertex. The effect of unquenching ... More
Thermoelectric power factor of a 70 nm Ni-nanowire in a magnetic fieldNov 08 2011Thermoelectric (TE) properties of a single nanowire (NW) are investigated in a microlab which allows the determination of the Seebeck coefficient S and the conductivity {\sigma}. A significiant influence of the magnetization of a 70 nm ferromagnetic Ni-NW ... More
Natural $Z'$ model with an inverse seesaw and leptonic dark matterJul 13 2012Feb 13 2013We consider a model for a Z'-boson coupled only to baryon minus lepton number and hypercharge. Besides the usual right-handed neutrinos, we add a pair of fermions with a fractional lepton charge, which we therefore call leptinos. One of the leptinos is ... More
Radio-frequency dressed state potentials for neutral atomsAug 29 2006Potentials for atoms can be created by external fields acting on properties like magnetic moment, charge, polarizability, or by oscillating fields which couple internal states. The most prominent realization of the latter is the optical dipole potential ... More
A singlet-triplet extension for the Higgs search at LEP and LHCDec 21 2012We describe a simple extension of the standard model, containing a scalar singlet and a triplet fermion. The model can explain the possible enhancement in the decay $H \rightarrow \gamma \gamma$ at the LHC together with the excess found in the Higgs boson ... More
Far-Infrared ISO Limits on Dust Disks around Millisecond PulsarsSep 26 2001We report 60 and 90 micron observations of 7 millisecond pulsars with the ISOPHOT instrument and describe our analysis procedures. No pulsars were detected, and typical (3\sigma) upper limits are 150 mJy. We combine our results with others in the literature ... More
Future prospects for inference on solar-type starsSep 28 2011We discuss prospects for asteroseismic inference on solar-type stars, in particular opportunities that are being made possible by the large ensemble of exquisite-quality Kepler data.
One Repeat Point Gives a Closed, Unbounded Ultrafilter on {ω_1}Mar 19 2014It is shown that the consistency strength of ZF + DC + "the closed unbounded ultrafilter on omega_1 is an ultrafilter" is exactly ZFC + one measurable cardinal.
I[omega_2] can be the nonstationary ideal on Cof(omega_1)Jul 13 2004Apr 30 2007We answer a question of Shelah by showing that it is consistent that every set of ordinals of cofinality omega_1 in I[omega_2] is nonstationary if and only if it is consistent that that there is a kappa^+ Mahlo cardinal kappa.
Inference of Boundaries in Causal SetsOct 26 2017Jun 26 2018We investigate the extrinsic geometry of causal sets in $(1+1)$-dimensional Minkowski spacetime. The properties of boundaries in an embedding space can be used not only to measure observables, but also to supplement the discrete action in the partition ... More
The part-frequency matrices of a partitionJan 05 2016A new combinatorial object is introduced, the part-frequency matrix sequence of a partition, which is elementary to describe and is naturally motivated by Glaisher's bijection. We prove results that suggest surprising usefulness for such a simple tool, ... More
CP Violation in Charged Higgs ProductionMay 13 2005I present a study estimating the amount of CP violation present in the production of charged Higgs bosons due to the presence of complex trilinear scalar couplings. I compare the results of my study with previous results for the decay. I briefly comment ... More
Optimal conditions for observing Josephson oscillations in a double-well Bose-gas condensateFeb 08 2001The Josephson oscillations between condensates in a double-well trap are known theoretically to be strongly effected by the mean field interaction in dilute atomic gases. The most important effect is that the amplitude of oscillation in the relative population ... More
Recent QCD Results from LEP-1 and LEP-2Mar 12 1999A summary is given of some recent QCD results from LEP. For LEP-2, the topics include event shape measurements, determinations of the strong coupling constant, and measurements of the charged particle multiplicity distribution at the recently completed ... More
The Loop-Gas Approach to Bose-Einstein Condensation for Trapped ParticlesJun 11 1999We examine Bose-Einstein condensation (BEC) for particles trapped in a harmonic potential by considering it as a transition in the length of permutation cycles that arise from wave-function symmetry. This ``loop-gas'' approach was originally developed ... More
Distribution of the full rank in residue classes for odd moduliMay 22 2009The distribution of values of the full ranks of marked Durfee symbols is examined in prime and nonprime arithmetic progressions. The relative populations of different residues for the same modulus are determined: the primary result is that k-marked Durfee ... More
Polynomial analogues of Ramanujan congruences for Han's hooklength formulaSep 06 2011Oct 15 2012This article considers the eta power $\prod {(1-q^k)}^{b-1}$. It is proved that the coefficients of $\frac{q^n}{n!}$ in this expression, as polynomials in $b$, exhibit equidistribution of the coefficients in the nonzero residue classes mod 5 when $n=5j+4$. ... More
System Parameters for the Eclipsing B-Star Binary HD 42401Sep 22 2008Nov 19 2008I present results from an optical spectroscopic investigation of the binary system HD 42401 (V1388 Ori; B2.5 IV-V + B3 V). A combined analysis of V-band photometry and radial velocities indicates that the system has an orbital period of 2.18706 +/- 0.00005 ... More
A construction of critical GJMS operators using Wodzicki's residueMar 23 2004Jan 13 2005For an even dimensional, compact, conformal manifold without boundary we construct a conformally invariant differential operator of order the dimension of the manifold. In the conformally flat case, this operator coincides with the critical {\sf GJMS} ... More
Differential forms and the Wodzicki residueNov 22 2002Feb 27 2003For a pseudodifferential operator $S$ of order 0 acting on sections of a vector bundle $B$ on a compact manifold $M$ without boundary, we associate a differential form of order dimension of $M$ acting on $C^\infty(M)\times C^\infty(M)$. This differential ... More
On an early paper of Maryam MirzakhaniSep 21 2017Oct 17 2017Maryam Mirzakhani, the first female (and first Iranian) Fields Medalist, passed away on July 14, 2017 at the age of 40. This short note remembers her 1996 article in the Bulletin of the Institute of Combinatorics and its Applications and her early years ... More
The Slide Dimension of Point ProcessesApr 16 2014We associate with any finite subset of a metric space an infinite sequence of scale invariant numbers $\rho_1,\rho_2,\dots$ derived from a variant of differential entropy called the genial entropy. As statistics for point processes, these numbers often ... More