Results for "C. Simenel"

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Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nucleiJan 20 2016Feb 10 2016Octupole vibrations are studied in some doubly magic nuclei using the time-dependent Hartree-Fock (TDHF) theory with a Skyrme energy density functional. Through the use of the linear response theory, the energies and transition amplitudes of the low-lying ... More
Non-Linear Vibrations in NucleiSep 23 2002Jul 21 2004We have perfomed Time Dependant Hartree-Fock (TDHF) calculations on the non linear response of nuclei. We have shown that quadrupole (and dipole) motion produces monopole (and quadrupole) oscillations in all atomic nuclei. We have shown that these findings ... More
Formation and dynamics of fission fragmentsDec 17 2013Mar 13 2014Although the overall time-scale for nuclear fission is long, suggesting a slow process, rapid shape evolution occurs in its later stages near scission. Theoretical prediction of the fission fragments and their characteristics are often based on the assumption ... More
Quantum Calculation of Dipole Excitation in Fusion ReactionNov 10 2000Jul 21 2004The excitation of the giant dipole resonance by fusion is studied with N/Z asymmetry in the entrance channel. the TDHF solution exhibits a strong dipole vibration which can be associated with a giant vibration along the main axis of a fluctuating prolate ... More
Transport properties of isospin asymmetric nuclear matter using TDHFJun 15 2017Jun 25 2017Background: The study of deep-inelastic reactions of nuclei provide a vehicle to investigate nuclear transport phenomena for a full range of equilibration dynamics. These inquires provide us the ingredients to model such phenomena and help answer important ... More
Isospin coupling in time-dependent-mean-field theories and decay of isovector excitationsApr 15 2005We show that isospin non-diagonal terms should appear in the mean field Hamiltonian when neutron-proton symmetry is broken. They give rise to charge mixing in the single-particle wave-functions. We study the Time Dependent Hartree-Fock response of a charge-exchange ... More
Dependence of fusion on isospin dynamicsSep 27 2016We introduce a new microscopic approach to calculate the dependence of fusion barriers and cross-sections on isospin dynamics. The method is based on the time-dependent Hartree-Fock theory and the isoscalar and isovector properties of the energy density ... More
Equilibration dynamics and isospin effects in nuclear reactionsApr 12 2019We discuss equilibration times and isospin effect for various quantities in low-energy heavy-ion reactions. These include equilibration of mass, isospin, and total kinetic energy (TKE) in quasifission and deep-inelastic reactions. The calculations are ... More
Deformed shell effects in $^{48}$Ca+$^{249}$Bk quasifission fragmentsJun 18 2019Background: Quasifission is the main reaction channel hindering the formation of superheavy nuclei (SHN). Its understanding will help to optimize entrance channels for SHN studies. Quasifission also provides a probe to understand the influence of shell ... More
Absence of hindrance in microscopic $^{12}$C+$^{12}$C fusion studyJun 05 2019Background: Studies of low-energy fusion of light nuclei are important in astrophysical modeling, with small variations in reaction rates having a large impact on nucleosynthesis yields. Due to the lack of experimental data at astrophysical energies, ... More
Isovector properties of the nuclear energy density functional from the quark-meson coupling modelApr 26 2017Background: The Skyrme energy density functional is widely used in mean-field calculations of nuclear structure and dynamics. However, its reliance on phenomenology may compromise its isovector properties and its performance for exotic nuclear systems. ... More
Dynamical effects in fusion with exotic nucleiJun 24 2016[Background] Reactions with stable beams have demonstrated a strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. ... More
Energy dependence of potential barriers and its effect on fusion cross-sectionsJan 28 2014Couplings between relative motion and internal structures are known to affect fusion barriers by dynamically modifying the densities of the colliding nuclei. The effect is expected to be stronger at energies near the barrier top, where changes in density ... More
Microscopic approach to coupled-channels effects on fusionOct 24 2013Dec 01 2013Background: Near-barrier fusion can be strongly affected by the coupling between relative motion and internal degrees of freedom of the collision partners. The time-dependent Hartree-Fock (TDHF) theory and the coupled-channels (CC) method are standard ... More
Superfluid fission dynamics with microscopic approachesJan 19 2016Recent progresses in the description of the latter stage of nuclear fission are reported. Dynamical effects during the descent of the potential towards scission and in the formation of the fission fragments are studied with the time-dependent Hartree-Fock ... More
Quasifission dynamics in TDHFAug 19 2015For light and medium mass systems the capture cross-section may be considered to be the same as that for complete fusion, whereas for heavy systems leading to superheavy formations the evaporation residue cross-section is dramatically reduced due to the ... More
Fusion and quasifission dynamics in the reactions $^{48}$Ca+$^{249}$Bk and $^{50}$Ti+$^{249}$Bk using TDHFJun 02 2016Background: Synthesis of superheavy elements (SHE) with fusion-evaporation reactions is strongly hindered by the quasifission (QF) mechanism which prevents the formation of an equilibrated compound nucleus and which depends on the structure of the reactants. ... More
Dynamics of quasifissionJul 30 2015Quasifission is the primary reaction mechanism that limits the formation of superheavy nuclei and consequently an important ingredient for choosing the best target-projectile combinations for the heavy element searches. Quasifission is characterized by ... More
Microscopic study of $^{16}$O+$^{16}$O fusionJun 24 2013Aug 31 2013We perform a study of $^{16}$O+$^{16}$O fusion at above and below the interaction barrier energies using three-dimensional time-dependent Hartree-Fock (TDHF) calculations at above barrier energies and density-constrained TDHF calculations for the entire ... More
Dissipative dynamics in quasi-fissionSep 10 2014Quasi-fission is the primary reaction mechanism that prevents the formation of superheavy elements in heavy-ion fusion experiments. Employing the time-dependent density functional theory approach we study quasi-fission in the systems $^{40,48}$Ca+$^{238}$U. ... More
Nuclear Quantum Many-Body Dynamics: From Collective Vibrations to Heavy-Ion CollisionsSep 15 2012Nov 08 2012A summary of recent researches on nuclear dynamics with realistic microscopic quantum approaches is presented. The Balian-V\'en\'eroni variational principle is used to derive the time-dependent Hartree-Fock (TDHF) equation describing the dynamics at the ... More
Shape evolution and collective dynamics of quasifission in TDHFJun 23 2015Background: At energies near the Coulomb barrier, capture reactions in heavy-ion collisions result either in fusion or in quasifission. The former produces a compound nucleus in statistical equilibrium, while the second leads to a reseparation of the ... More
Microscopic study of $^{40}$Ca+$^{58,64}$Ni fusion reactionsFeb 17 2016Background: Heavy-ion fusion reactions at energies near the Coulomb barrier are influenced by couplings between the relative motion and nuclear intrinsic degrees of freedom of the colliding nuclei. The time-dependent Hartree-Fock (TDHF) theory, incorporating ... More
Particle number fluctuations and correlations in transfer reactions obtained using the Balian-Vénéroni variational principleNov 10 2010Feb 21 2011The Balian-V\'en\'eroni (BV) variational principle, which optimizes the evolution of the state according to the relevant observable in a given variational space, is used at the mean-field level to determine the particle number fluctuations in fragments ... More
Particle transfer reactions with the time-dependent Hartree-Fock theory using a particle number projection techniqueAug 18 2010Nov 08 2010A particle-number projection technique is used to calculate transfer probabilities in the $^{16}$O+$^{208}$Pb reaction below the fusion barrier. The time evolution of the many-body wave function is obtained with the time-dependent Hartree-Fock (TDHF) ... More
From light to hyper-heavy molecules and neutron-star crusts in a dynamical mean-field approachNov 11 2012The richness of phenomena occurring in heavy-ion collisions calls for microscopic approaches where the motion of each nucleon is treated quantum mechanically. The most popular microscopic approach for low-energy collisions between atomic nuclei is the ... More
Probing quantum many-body dynamics in nuclear systemsAug 23 2013Aug 31 2013Quantum many-body nuclear dynamics is treated at the mean-field level with the time-dependent Hartree-Fock (TDHF) theory. Low-lying and high-lying nuclear vibrations are studied using the linear response theory. The fusion mechanism is also described ... More
Effect of shell structure on the fission of sub-lead nucleiApr 02 2019Fission of atomic nuclei often produces mass asymmetric fragments. However, the origin of this asymmetry was believed to be different in actinides and in the sub-lead region [A. Andreyev et al., Phys. Rev. Lett. 105, 252502 (2010)]. It has recently been ... More
How the Pauli exclusion principle affects fusion of atomic nucleiOct 09 2016The Pauli exclusion principle induces a repulsion between composite systems of identical fermions such as colliding atomic nuclei. Our goal is to study how heavy-ion fusion is impacted by this "Pauli repulsion". We propose a new microscopic approach, ... More
Microscopic study of the effect of intrinsic degrees of freedom on fusionApr 11 2014Fusion cross-sections are computed for the $^{40}$Ca$+^{40}$Ca system over a wide energy range with two microscopic approaches where the only phenomenological input is the Skyrme energy density functional. The first method is based on the coupled-channels ... More
Time-Depentent Hartree-Fock description of heavy ions fusionNov 06 2007A microscopic mean-field description of heavy ions fusion is performed in the framework of the Time-Dependent Hartree-Fock (TDHF) theory using a Skyrme interaction with the SLy4d parametrization. A good agreement with experiments is obtained on the position ... More
Coupled collective motion in nuclear reactionsSep 15 2003In this paper, we review the roles of collective modes in nuclear reactions. We emphaize the strong couplings of various collective states with the monopole and quadrupole motions. In inelastic excitation, these couplings can be seen as an important source ... More
On the origin of asymmetric fission of actinidesApr 10 2018Nov 03 2018Background: Nuclear fission of most actinides near the valley of stability is dominated by asymmetric modes with a heavy fragment charge distribution centred around $Z\approx52-55$ protons. Although spherical shell effects in the $^{132}$Sn are often ... More
Effect of Octupole correlations on Fission of Light NucleiJul 10 2019Fission of $^{180}$Hg produces mass asymmetric fragments which are expected to be influenced by deformed shell-effects at N=56 in the heavy fragment and Z=34 in the light fragment [G. Scamps and C. Simenel, arXiv:1904.01275 (2019)]. To investigate both ... More
Effect of Pauli repulsion and transfer on fusionMay 31 2017The effect of the Pauli exclusion principle on the nucleus-nucleus bare potential is studied using a new density-constrained extension of the Frozen-Hartree-Fock (DCFHF) technique. The resulting potentials exhibit a repulsion at short distance. The charge ... More
Influence of entrance-channel magicity and isospin on quasi-fissionNov 11 2011Mar 26 2012The role of spherical quantum shells in the competition between fusion and quasi-fission is studied for reactions forming heavy elements. Measurements of fission fragment mass distributions for different reactions leading to similar compound nuclei have ... More
Couplings between dipole and quadrupole vibrations in tin isotopesSep 11 2009Dec 11 2009We study the couplings between collective vibrations such as the isovector giant dipole and isoscalar giant quadrupole resonances in tin isotopes in the framework of the time-dependent Hartree-Fock theory with a Skyrme energy density functional. These ... More
Collision dynamics of two $^{238}$U atomic nucleiApr 20 2009Jun 02 2009Collisions of actinide nuclei form, during very short times of few $10^{-21}$ s, the heaviest ensembles of interacting nucleons available on Earth. Such very heavy ions collisions have been proposed as an alternative way to produce heavy and superheavy ... More
Novel insights into transfer processes in the reaction 16O+208Pb at sub-barrier energiesJan 07 2011The collision of the doubly-magic nuclei $^{16}$O+$^{208}$Pb is a benchmark in nuclear reaction studies. Our new measurements of back-scattered projectile-like fragments at sub-barrier energies show show that transfer of 2 protons ($2p$) is much more ... More
Interplay between quantum shells and orientation in quasi-fissionJun 23 2014Oct 08 2014The quasi-fission mechanism hinders fusion in heavy systems through breakup within zeptoseconds into two fragments with partial mass equilibration. Its dependence on the structure of both the collision partners and the final fragments is a key question. ... More
Effects of Nuclear Structure on Quasi-fissionOct 03 2012The quasi-fission mechanism hinders fusion of heavy systems because of a mass flow between the reactants, leading to a re-separation of more symmetric fragments in the exit channel. A good understanding of the competition between fusion and quasi-fission ... More
Investigation of the role of shell structure in quasi-fission mass distributionsNov 21 2011Systematic measurements of mass-ratio distributions for fission following collisions of $^{48}$Ti projectiles with even-even target nuclei from $^{144}$Sm to $^{208}$Pb have been made at sub-barrier energies. They show the presence of quasifission, and ... More
Fusion process studied with preequilibrium giant dipole resonance in time dependent Hartree-Fock theoryApr 04 2007Aug 24 2007The equilibration of macroscopic degrees of freedom during the fusion of heavy nuclei, like the charge and the shape, are studied in the Time-Dependent Hartree-Fock theory. The pre-equilibrium Giant Dipole Resonance (GDR) is used to probe the fusion path. ... More
Exploring Zeptosecond Quantum Equilibration Dynamics: From Deep-Inelastic to Fusion-Fission Outcomes in $^{58}$Ni+$^{60}$Ni ReactionsDec 26 2017Energy dissipative processes play a key role in how quantum many-body systems dynamically evolve towards equilibrium. In closed quantum systems, such processes are attributed to the transfer of energy from collective motion to single-particle degrees ... More
Quantum calculations of Coulomb reorientation for sub-barrier fusionJan 21 2004Jul 28 2004Classical mechanics and Time Dependent Hartree-Fock (TDHF) calculations of heavy ions collisions are performed to study the rotation of a deformed nucleus in the Coulomb field of its partner. This reorientation is shown to be independent on charges and ... More
Pairing Vibrations Study with the Time-Dependent Hartree-Fock-Bogoliubov theoryAug 26 2008Sep 26 2008We study pairing vibrations in $^{18,20,22}$O and $^{42,44,46}$Ca nuclei solving the time-dependent Hartree-Fock-Bogoliubov equation in coordinate space with spherical symmetry. We use the SLy4 Skyrme functional in the normal part of the energy density ... More
Microscopic description of heavy ion collisions around the barrierApr 17 2009A microscopic mean-field description of heavy ion collisions is performed in the framework of the time dependent Hartree-Fock theory using a Skyrme energy density functional. A good agreement with experiments is obtained on the position of the fusion ... More
Actinide collisions for QED and superheavy elements with the time-dependent Hartree-Fock theory and the Balian-Vénéroni variational principleAug 11 2011Collisions of actinide nuclei form, during very short times of few zs ($10^{-21}$ s), the heaviest ensembles of interacting nucleons available on Earth. Such collisions are used to produce super-strong electric fields by the huge number of interacting ... More
Quantum microscopic approach to low-energy heavy ion collisionsSep 04 2012Oct 03 2012The Time-dependent Hartree-Fock (TDHF) theory is applied to the study of heavy ion collisions at energies around the Coulomb barrier. The competition between fusion and nucleon transfer mechanisms is investigated. For intermediate mass systems such as ... More
Dynamical description of the fission process using the TD-BCS theoryAug 05 2015The description of fission remains a challenge for nuclear microscopic theories. The time-dependent Hartree-Fock approach with BCS pairing is applied to study the last stage of the fission process. A good agreement is found for the one-body observables: ... More
Superfluid dynamics of 258Fm fissionJan 15 2015Theoretical description of nuclear fission remains one of the major challenges of quantum many-body dynamics. The slow, mostly adiabatic motion through the fission barrier is followed by a fast, non-adiabatic descent of the potential between the fragments. ... More
Microscopic approaches for nuclear Many-Body dynamics: applications to nuclear reactionsJun 17 2008Apr 20 2009These lecture notes are addressed to PhD student and/or researchers who want a general overview of microscopic approaches based on mean-field and applied to nuclear dynamics. Our goal is to provide a good description of low energy heavy-ion collisions. ... More
The Role of Tensor Force in Heavy-Ion Fusion DynamicsMay 24 2018Jul 18 2018The tensor force is implemented into the time-dependent Hartree-Fock (TDHF) theory so that both exotic and stable collision partners, as well as their dynamics in heavy-ion fusion, can be described microscopically. The role of tensor force on fusion dynamics ... More
Microscopic description of large amplitude collective motion in the nuclear astrophysics contextMay 13 2015In the last 10 years, we have observed an important increase of interest in the application of time-dependent energy density functional theory (TD-EDF). This approach allows to treat nuclear structure and nuclear reaction from small to large amplitude ... More
Reduced quasifission competition in fusion reactions forming neutron-rich heavy elementsApr 13 2015Measurements of mass-angle distributions (MADs) for Cr + W reactions, providing a wide range in the neutron-to-proton ratio of the compound system, (N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be determined in a model-independent ... More
Study of $^{124}$Sn+$^{136}$Xe fusion-evaporation: analysis of a rare-event experimentNov 12 2011Nov 22 2011Fusion-evaporation in the $^{124}$Sn+$^{136}$Xe system is studied using a high intensity xenon beam provided by the Ganil accelerator and the LISE3 wien filter for the selection of the products. Due to the mass symmetry of the entrance system, the rejection ... More
Entrance Channel Effects on the Quasifission Reaction Channel in Cr + W SystemsMar 16 2017Mar 17 2017Background: Formation of a fully equilibrated compound nucleus is a critical step in the heavy-ion fusion reaction mechanism but can be hindered by orders of magnitude by quasifission, a process in which the dinuclear system breaks apart prior to full ... More
Evidence for the role of proton shell closure in quasi-fission reactions from X-ray fluorescence of mass-identified fragmentsOct 26 2017The atomic numbers and the masses of fragments formed in quasi-fission reactions have been simultaneously measured at scission in 48 Ti + 238 U reactions at a laboratory energy of 286 MeV. The atomic numbers were determined from measured characteristic ... More
Gamow-Teller strengths in 24Na using the 24Mg(t,3He) reaction at 115 AMeVJul 15 2008Gamow-Teller transitions from 24Mg to 24Na were studied via the (t,3He) reaction at 115 AMeV using a secondary triton beam produced via fast fragmentation of 150 AMeV 16O ions. Compared to previous (t,3He) experiments at this energy that employed a primary ... More
On the extraction of weak transition strengths via the (3He,t) reaction at 420 MeVJul 19 2007Mar 27 2008Differential cross sections for transitions of known weak strength were measured with the (3He,t) reaction at 420 MeV on targets of 12C, 13C, 18O, 26Mg, 58Ni, 60Ni, 90Zr, 118Sn, 120Sn and 208Pb. Using this data, it is shown the proportionalities between ... More
Quantum calculation of Coulomb reorientation and near-barrier fusionMay 08 2006We investigate the role of deformation on the fusion probability around the barrier using the Time-Dependent Hartree-Fock theory with a full Skyrme force. We obtain a distribution of fusion probabilities around the nominal barrier due to the different ... More
Generating functional analysis of Minority Games with real market historiesOct 13 2004It is shown how the generating functional method of De Dominicis can be used to solve the dynamics of the original version of the minority game (MG), in which agents observe real as opposed to fake market histories. Here one again finds exact closed equations ... More
Statistical Mechanics of Recurrent Neural Networks II. DynamicsJun 01 2000A lecture notes style review of the non-equilibrium statistical mechanics of recurrent neural networks with discrete and continuous neurons (e.g. Ising, graded-response, coupled-oscillators). To be published in the Handbook of Biological Physics (North-Holland). ... More
Non-equilibrium statistical mechanics of Minority GamesMay 13 2002In this paper I give a brief introduction to a family of simple but non-trivial models designed to increase our understanding of collective processes in markets, the so-called Minority Games, and their non-equilibrium statistical mathematical analysis. ... More
NSV 13983: A New Dwarf Nova in the Period GapJun 17 2008Aims. NSV 13983 is catalogued as a dwarf nova based on a reported outburst from 2005. The system has not yet been studied spectroscopically. We attempt to confirm its nature as a dwarf nova and determine its orbital period. Methods. We derive the orbital ... More
Computation of the topological type of a real Riemann surfaceApr 21 2012We present an algorithm for the computation of the topological type of a real compact Riemann surface associated to an algebraic curve, i.e., its genus and the properties of the set of fixed points of the anti-holomorphic involution $\tau$, namely, the ... More
A new and trivial CP symmetry for extended $A_4$ flavorJan 05 2016May 18 2016The combination of $\nu_\mu$-$\nu_\tau$ exchange together with CP conjugation in the neutrino sector (known as $\mathrm{CP}^{\mu\tau}$ symmetry or $\mu\tau$-reflection) is known to predict the viable pattern: $\theta_{23}=45^\circ$, maximal Dirac CP phase ... More
Scaling of the superfluid density in severely underdoped YBa2Cu3O6+yNov 20 2009Recent measurements on extremely-underdoped YBa2Cu3O6+y [Phys. Rev. Lett. 99, 237003 (2007)] have allowed the critical temperature (T_c), superfluid density [rho_0 (T << T_c)] and dc conductivity [sigma_dc (T ~ T_c)] to be determined for a series of electronic ... More
Quantum-mechanical picture of peripheral chiral dynamicsMar 06 2015The nucleon's peripheral transverse charge and magnetization densities are computed in chiral effective field theory. The densities are represented in first-quantized form, as overlap integrals of chiral light-front wave functions describing the transition ... More
Eclipsing Binary PulsarsApr 05 2004The first eclipsing binary pulsar, PSR B1957+20, was discovered in 1987. Since then, 13 other eclipsing low-mass binary pulsars have been found, 12 of these are in globular clusters. In this paper we list the known eclipsing binary pulsars and their properties, ... More
Poincare duality in dimension 3Oct 03 2004The paper gives a review of progress towards extending the Thurston programme to the Poincare duality case. For a full abstract, see the published version at the above link.
The Pulsar Population in Globular Clusters and in the GalaxyOct 15 2012Oct 23 2012In this paper, I review some of the basic properties of the pulsar population in globular clusters (GCs) and compare it with the the Galactic disk population. The neutron stars (NSs) in GCs were likely formed - and appear to continue forming - in highly ... More
Decay width of light quark hybrid meson from the latticeMar 06 2006Apr 13 2006Lattice QCD with $N_f=2$ flavours of sea quark is used to explore the spectrum and decay of a $J^{PC}=1^{-+}$ spin-exotic hybrid meson. We test lattice determination of S-wave decay amplitudes at threshold using $b_1 \to \pi \omega$ where agreement with ... More
Staggered Chiral Perturbation Theory with Heavy-Light MesonsSep 08 2004We merge heavy quark effective theory with staggered chiral perturbation theory to calculate heavy-light (B, D) meson quantities. We present results at NLO for the $B(D)$ meson decay constant in the partially quenched and full QCD cases, and discuss the ... More
Transverse stability of periodic traveling waves in Kadomtsev-Petviashvili equations: A numerical studyAug 16 2011We numerically investigate transverse stability and instability of so-called cnoidal waves, i.e., periodic traveling wave solutions of the Korteweg-de Vries equation, under the time-evolution of the Kadomtsev-Petviashvili equation. In particular, we find ... More
Azimuthal decorrelation of Mueller-Navelet jets at the Tevatron and the LHCApr 25 2007Nov 05 2008We study the production of Mueller-Navelet jets at hadron colliders in the Balitsky-Fadin-Kuraev-Lipatov (BFKL) framework. We show that a measurement of the relative azimuthal angle \Delta\Phi between the jets can provide a good testing ground for corrections ... More
High-dielectric constant and wide band gap inverse silver oxide phases of the ordered ternary alloys of SiO$_{2}$, GeO$_{2}$ and SnO$_{2}$Jul 14 2006Dec 01 2006High-dielectric constant and wide band gap oxides have important technological applications. The crystalline oxide polymorphs having lattice constant compatibility to silicon are particularly desirable. One recently reported candidate is the inverse silver ... More
Single crystal growth and anisotropy of CeRuPOSep 26 2007Dec 05 2007We report on the single crystal growth of the ferromagnetic Kondo lattice system CeRuPO using a Sn flux method. Magnetic susceptibility and electrical resistivity measurements indicate strong anisotropy of this structurally layered compound. They evidence ... More
8--13 micron spectroscopy of luminous and ultraluminous infrared galaxiesMar 17 1999New moderate-resolution mid-infrared spectroscopy at 10 micron of 27 infrared galaxies is presented. The galaxies have been chosen from three 60 micron selected and one 12 micron selected complete flux-limited catalogs of galaxies; 17 of these sources ... More
Solving the mystery of IapetusApr 29 2005Jul 19 2007For a much better-founded theory, check Wing Ip, GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L16203, doi:10.1029/2005GL025386, 2006 (see also
Transverse charge and magnetization densities in the nucleon's chiral peripheryOct 02 2013In the light-front description of nucleon structure the electromagnetic form factors are expressed in terms of frame-independent transverse densities of charge and magnetization. Recent work has studied the transverse densities at peripheral distances ... More
Chiral dynamics and peripheral transverse densitiesAug 07 2013In the partonic (or light-front) description of relativistic systems the electromagnetic form factors are expressed in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral ... More
FIRST `Winged' and `X'-shaped Radio Source CandidatesJan 10 2007Mar 16 2008A small number of double-lobed radio galaxies (17 from our own census of the literature) show an additional pair of low surface brightness `wings', thus forming an overall `X'-shaped appearance. The origin of the wings in these radio sources is unclear. ... More
Compton X-ray and Gamma-ray Emission from Extended Radio GalaxiesApr 06 2007The extended lobes of radio galaxies are examined as sources of X-ray and gamma-ray emission via inverse Compton scattering of 3K background photons. The Compton spectra of two exemplary examples, Fornax A and Centaurus A, are estimated using available ... More
Panchromatic Views of Large-scale Extragalactic JetsDec 14 2006Highlights of recent observations of extended jets in AGN are presented. Specifically, we discuss new spectral constraints enabled by Spitzer, studies of the highest-redshift (z~4) radio/X-ray quasar jets, and a new VLBA detection of superluminal motion ... More
Elements stability: a microcosmos effect?Sep 13 2006The electronic structure of heavy elements, when described in a space-time which the metric is affected by the electromagnetic interaction, presents instabilities. These instabilities increase with the atomic number, and above a critical value, become ... More
Modified Newtonian Mechanics from an interpolating metricJan 04 2016Jun 22 2018A few years ago Baker \cite{baker} proposed a Lema$\hat{i}$tre-Tolman metric to interpolate smoothly between the Schwarzschild metric at small scales and the Friedmann-Robertson-Walker (FRW) metric at large scales. As it stands, by implementing the Bona-Stela ... More
Series of convex functions: subdifferential, conjugate and applications to entropy minimizationJun 03 2015A formula for the sub\-differential of the sum of a series of convex functions defined on a Banach space was provided by X. Y. Zheng in 1998. In this paper, besides a slight extension to locally convex spaces of Zheng's results, we provide a formula for ... More
Torsion cohomology classes and algebraic cycles on complex projective manifoldsMar 16 2004Jan 15 2005Atiyah and Hirzebruch gave examples ofeven degree torsion classes in the singularcohomology of a smooth complex projective manifold, which arenot Poincar\'{e} dual to an algebraiccycle. We notice that the order ofthese classes are small comparedto the ... More
Understanding Convolutional Neural Networks with A Mathematical ModelSep 14 2016This work attempts to address two fundamental questions about the structure of the convolutional neural networks (CNN): 1) why a non-linear activation function is essential at the filter output of every convolutional layer? 2) what is the advantage of ... More
Threshold effects in open-string theoryMay 05 1996May 14 1996We analyze the one-loop effective gauge-field action in $Z_2$-orbifold compactifications of type-I theory. We show how, for non-abelian group factors, the threshold effects are ultraviolet finite though given entirely by a six-dimensional field theory ... More
Hidden Symmetry of a Fluid Dynamical ModelMay 28 2001A connection between solutions of the relativistic d-brane system in (d+1) dimensions with the solutions of a Galileo invariant fluid in d-dimensions is by now well established. However, the physical nature of the light-cone gauge description of a relativistic ... More
A quantum topological phase transition at the microscopic levelJul 13 2007Mar 01 2008We study a quantum phase transition between a phase which is topologically ordered and one which is not. We focus on a spin model, an extension of the toric code, for which we obtain the exact ground state for all values of the coupling constant that ... More
Explicit Gravitational Radiation in Hyperbolic Systems for Numerical RelativityFeb 14 2002Feb 28 2002A method for studying the causal structure of space-time evolution systems is presented. This method, based on a generalization of the well known Riemann problem, provides intrinsic results which can be interpreted from the geometrical point of view. ... More
Flux Limiter Methods in 3D Numerical RelativityFeb 28 2002New numerical methods have been applied in relativity to obtain a numerical evolution of Einstein equations much more robust and stable. Starting from 3+1 formalism and with the evolution equations written as a FOFCH (first-order flux conservative hyperbolic) ... More
Staggered Chiral Perturbation Theory for Heavy-Light MesonsOct 18 2005Jan 25 2006We incorporate heavy-light mesons into staggered chiral perturbation theory, working to leading order in 1/m_Q, where m_Q is the heavy quark mass. At first non-trivial order in the chiral expansion, staggered taste violations affect the chiral logarithms ... More
Replica methods for loopy sparse random graphsJan 29 2016I report on the development of a novel statistical mechanical formalism for the analysis of random graphs with many short loops, and processes on such graphs. The graphs are defined via maximum entropy ensembles, in which both the degrees (via hard constraints) ... More
Statistical Mechanics of Recurrent Neural Networks I. StaticsJun 01 2000A lecture notes style review of the equilibrium statistical mechanics of recurrent neural networks with discrete and continuous neurons (e.g. Ising, coupled-oscillators). To be published in the Handbook of Biological Physics (North-Holland). Accompanied ... More
Light-front representation of chiral dynamics with Delta isobar and large-N_c relationsMar 29 2016Transverse densities describe the spatial distribution of electromagnetic current in the nucleon at fixed light-front time. At peripheral distances b = O(M_pi^{-1}) the densities are governed by chiral dynamics and can be calculated model-independently ... More
Radio Identification of the X-ray Jet in the z=4.3 Quasar GB 1508+5714Oct 25 2003Dec 01 2003The recent discovery of an X-ray jet in the z=4.3 quasar GB 1508+5714 by Yuan et al. (astro-ph/0309318) and Siemiginowska et al. (astro-ph/0310241) prompted a search for its radio counterpart. Here, we report the successful discovery of faint radio emission ... More