Results for "N. R. Badnell"

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Dielectronic recombination of Fe 3p^q ions: a key ingredient for describing X-ray absorption in active galactic nucleiAug 16 2006We have carried-out multi-configuration Breit-Pauli AUTOSTRUCTURE calculations for the dielectronic recombination (DR) of Fe^{8+} - Fe^{12+} ions. We obtain total DR rate coefficients for the initial ground-level which are an order of magnitude larger ... More
Dielectronic recombination of Fe^{13+}: benchmarking the M-shellJul 18 2006We have carried-out a series of multi-configuration Breit-Pauli AUTOSTRUCTURE calculations for the dielectronic recombination of Fe^{13+}. We present a detailed comparison of the results with the high-energy resolution measurements reported recently from ... More
Radiative recombination data for modelling dynamic finite-density plasmasApr 06 2006We have calculated partial final-state resolved radiative recombination (RR) rate coefficients from the initial ground and metastable levels of all elements up to and including Zn, plus Kr, Mo, and Xe, for all isoelectronic sequences up to Na-like forming ... More
Opacities and Spectra of the r-process Ejecta from Neutron Star MergersMar 22 2013Material ejected during (or immediately following) the merger of two neutron stars may assemble into heavy elements by the r-process. The subsequent radioactive decay of the nuclei can power electromagnetic emission similar to, but significantly dimmer ... More
Electron-impact excitation of Fe$^{2+}$: a comparison of intermediate coupling frame transformation, Breit-Pauli and Dirac R-matrix calculationsFeb 19 2014Modeling the spectral emission of low-charge iron group ions enables the diagnostic determination of the local physical conditions of many cool plasma environments such as those found in H II regions, planetary nebulae, active galactic nuclei etc. Electron-impact ... More
On the importance of inner-shell transitions for opacity calculationsAug 22 2003For high temperatures and densities, stellar opacities obtained from the Opacity Project (OP) were smaller than those obtained from the OPAL project. Iglesias and Rogers [Ap.J. v443, 469 (1995)] suggested that the discrepancy was due to the omission by ... More
A comparison of Rosseland-mean opacities from OP and OPALApr 22 2004Monochromatic opacities from the Opacity Project (OP) (Seaton et al.) have been augmented by hitherto missing inner-shell contributions (Badnell & Seaton). OP Rosseland-mean opacities are compared with results from OPAL (Iglesias & Rogers) for the elements ... More
The electron energy-loss rate due to radiative recombinationDec 03 2016For photoionized plasmas, electron energy-loss rates due to radiative recombination (RR) are required for thermal equilib- rium calculations, which assume a local balance between the energy gain and loss. While many calculations of total and/or partial ... More
The Tungsten Project: Dielectronic Recombination Data For Collisional-RadiativeModelling In ITEROct 19 2016Tungsten is an important metal in nuclear fusion reactors. It will be used in the divertor component of ITER (Latin for 'the way'). The Tungsten Project aims to calculate partial and total DR rate coefficients for the isonuclear sequence of Tungsten. ... More
Scaling of collision strengths for highly-excited states of ions of the H- and He-like sequencesJul 08 2016Emission lines from highly-excited states (n >= 5) of H- and He-like ions have been detected in astrophysical sources and fusion plasmas. For such excited states, R-matrix or distorted wave calculations for electron-impact excitation are very limited, ... More
Dirac $R$-matrix and Breit-Pauli distorted wave calculations of the electron-impact excitation of W$^{44+}$Jun 12 2015Aug 27 2015With construction of ITER progressing and existing tokamaks carrying out ITER-relevant experiments, accurate fundamental and derived atomic data for numerous ionization stages of tungsten (W) is required to assess the potential effect of this species ... More
R-matrix inner-shell electron-impact excitation of Fe$^{15+}$ including Auger-plus-radiation dampingNov 05 2008We present results for the inner-shell electron-impact excitation of Fe$^{15+}$ using the intermediate-coupling frame transformation {\it R}-matrix approach in which Auger-plus-radiation damping has been included. The target and close-coupling expansions ... More
Validity of the ICFT R-matrix method: Be-like Al$^{9+}$ a case studyMar 17 2015Apr 20 2015We have carried-out 98-level configuration-interaction / close-coupling (CI/CC) intermediate coupling frame transformation (ICFT) and Breit-Pauli R-matrix calculations for the electron-impact excitation of Be-like Al$^{9+}$. The close agreement that we ... More
Uncertainties on atomic data. A case study: N IVJan 24 2019We consider three recent large-scale calculations for the radiative and electron-impact excitation data of N IV, carried out with different methods and codes. The scattering calculations employed the relativistic Dirac $R$-matrix (DARC) method, the intermediate ... More
The Tungsten Project: Dielectronic Recombination Data For Collisional-Radiative Modelling In ITEROct 19 2016Oct 23 2016Tungsten is an important metal in nuclear fusion reactors. It will be used in the divertor component of ITER (Latin for 'the way'). The Tungsten Project aims to calculate partial and total DR rate coefficients for the isonuclear sequence of Tungsten. ... More
Revised Results for Non-thermal Recombination Flare Hard X-Ray EmissionDec 17 2009Feb 24 2010Brown and Mallik (BM) recently showed that, for hot sources, recombination of non-thermal electrons (NTR) onto highly ionised heavy ions is not negligible compared to non-thermal bremsstrahlung (NTB) as a source of flare hard X-rays (HXRs) and so should ... More
Collision Strengths for [O III] Optical and Infrared LinesNov 25 2013We present electron collision strengths and their thermally averaged values for the forbidden lines of the astronomically abundant doubly-ionized oxygen ion, O^{2+}, in an intermediate coupling scheme using the Breit-Pauli relativistic terms as implemented ... More
Atomic data from the Iron Project. LXIV. Radiative transition rates and collision strengths for Ca IIApr 28 2007This work reports radiative transition rates and electron impact excitation rate coefficients for levels of the n= 3, 4, 5, 6, 7, 8 configurations of Ca II. The radiative data were computed using the Thomas-Fermi-Dirac central potential method in the ... More
Partial and Total Dielectronic Recombination rate coefficients for W73+ to W56+Mar 18 2016Dielectronic recombination (DR) is a key atomic process which affects the spectroscopic diagnostic modelling of tungsten, most of whose ionization stages will be found somewhere in the ITER fusion reactor: in the edge, divertor, or core plasma. Accurate ... More
Radiative transition rates and collision strengths for Si IIOct 28 2009Aims. This work reports radiative transition rates and electron impact excitation collision strengths for levels of the 3s23p, 3s3p2, 3s24s, and 3s23d configurations of Siii. Methods. The radiative data were computed using the Thomas-Fermi-Dirac-Amaldi ... More
Importance of the completeness of the configuration interaction and close coupling expansions in R-matrix calculations for highly-charged ions: electron-impact excitation of Fe $^{20+}$Nov 18 2015Apr 11 2016We have carried-out two intermediate coupling frame transformation (ICFT) R-matrix calculations for the electron-impact excitation of C-like Fe $^{20+}$, both of which use the same expansions for their configuration interaction (CI) and close-coupling ... More
Dielectronic Recombination of Argon-Like IonsMar 24 2010We present a theoretical investigation of dielectronic recombination (DR) of Ar-like ions that sheds new light on the behavior of the rate coefficient at low-temperatures where these ions form in photoionized plasmas. We provide results for the total ... More
Dielectronic recombination and stability of warm gas in AGNNov 07 2007Nov 14 2008Understanding the thermal equilibrium (stability) curve may offer insights into the nature of the warm absorbers often found in active galactic nuclei. Its shape is determined by factors like the spectrum of the ionizing continuum and the chemical composition ... More
Hot DA white dwarf model atmosphere calculations: Including improved Ni PI cross sectionsOct 30 2016To calculate realistic models of objects with Ni in their atmospheres, accurate atomic data for the relevant ionization stages needs to be included in model atmosphere calculations. In the context of white dwarf stars, we investigate the effect of changing ... More
Collisional Ionization Equilibrium for Optically Thin Plasmas. I. Updated Recombination Rate Coefficients for Bare though Sodium-like IonsApr 17 2006Aug 01 2006Reliably interpreting spectra from electron-ionized cosmic plasmas requires accurate ionization balance calculations for the plasma in question. However, much of the atomic data needed for these calculations have not been generated using modern theoretical ... More
Dielectronic recombination of W^20+ (4d^10 4f^8): addressing the half-open f-shellApr 10 2012A recent measurement of the dielectronic recombination (DR) of W^20+ [Schippers et al Phys. Rev. A83, 012711 (2011)] found an exceptionally large contribution from near threshold resonances (<1eV). This still affected the Maxwellian rate coefficient at ... More
A possible solution to the Lyman/Balmer line problem in hot DA white dwarfsOct 03 2014Arguably, the best method for determining the effective temperature ($T_{\mathrm{eff}}$) and surface gravity (log $g$) of a DA white dwarf is by fitting the Hydrogen Lyman and Balmer absorption features. However, as has been shown for white dwarfs with ... More
Bootstrapping dielectronic recombination from second-row elements and the Orion NebulaMar 19 2015Dielectronic recombination (DR) is the dominant recombination process for most heavy elements in photoionized clouds. Accurate DR rates for a species can be predicted when the positions of autoionizing states are known. Unfortunately such data are not ... More
Suppression of Dielectronic Recombination Due to Finite Density EffectsMar 10 2013We have developed a general model for determining density-dependent effective dielectronic recombination (DR) rate coefficients in order to explore finite-density effects on the ionization balance of plasmas. Our model consists of multiplying by a suppression ... More
R-matrix electron-impact excitation data for astrophysically abundant sulphur ionsJul 30 2011Aug 04 2011We present results for the electron-impact excitation of highly-charged sulphur ions (S8+ - S11+) obtained using the intermediate-coupling frame transformation R-matrix approach. A detailed comparison of the target structure has been made for the four ... More
H, He-like recombination spectra II: $l$-changing collisions for He Rydberg statesAug 31 2016Cosmological models can be constrained by determining primordial abundances. Accurate predictions of the He I spectrum are needed to determine the primordial helium abundance to a precision of $< 1$% in order to constrain Big Bang Nucleosynthesis models. ... More
H, He-like recombination spectra I: $l$-changing collisions for hydrogenApr 13 2016Hydrogen and helium emission lines in nebulae form by radiative recombination. This is a simple process which, in principle, can be described to very high precision. Ratios of He I and H I emission lines can be used to measure the He$^+$/H$^+$ abundance ... More
H-, He-like recombination spectra III: $n$-changing collisions in highly-excited Rydberg states and their impact on the radio, IR and optical recombination linesMar 13 2019At intermediate to high densities, electron (de-)excitation collisions are the dominant process for populating or depopulating high Rydberg states. In particular, the accurate knowledge of the energy changing ($n$-changing) collisional rates is determinant ... More
Up-dated opacities from the Opacity ProjectOct 29 2004Dec 18 2004Using the code AUTOSTRUCTURE, extensive calculations of inner-shell atomic data have been made for the chemical elements He, C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Cr, Mn, Fe and Ni. The results are used to obtain up-dated opacities from the Opacity ... More
H-, He-like recombination spectra III: $n$-changing collisions in highly-excited Rydberg states and their impact on the radio, IR and optical recombination linesMar 13 2019Mar 18 2019At intermediate to high densities, electron (de-)excitation collisions are the dominant process for populating or depopulating high Rydberg states. In particular, the accurate knowledge of the energy changing ($n$-changing) collisional rates is determinant ... More
Suppression of Dielectronic Recombination Due to Finite Density Effects II: Analytical Refinement and Application to Density-dependent Ionization Balances and AGN Broad-line EmissionAug 22 2018We present improved fits to our treatment of suppression of dielectronic recombination at intermediate densities. At low densities, most recombined excited states eventually decay to the ground state, and therefore the total dielectronic recombination ... More
Assessment of the Fluorescence and Auger Data Base used in Plasma ModelingApr 10 2003We have investigated the accuracy of the 1s-vacancy fluorescence data base of Kaastra & Mewe (1993, A&AS, 97, 443) resulting from the initial atomic physics calculations and the subsequent scaling along isoelectronic sequences. In particular, we have ... More
A Quantitative Comparison of Opacities Calculated Using the Distorted- Wave and $\boldsymbol{R}$-Matrix MethodsApr 10 2018The present debate on the reliability of astrophysical opacities has reached a new climax with the recent measurements of Fe opacities on the Z-machine at the Sandia National Laboratory \citep{Bailey2015}. To understand the differences between theoretical ... More
Recombination of W18+ ions with electrons: Absolute rate coefficients from a storage-ring experiment and from theoretical calculationsSep 08 2014We present new experimentally measured and theoretically calculated rate coefficients for the electron-ion recombination of W$^{18+}$([Kr] $4d^{10}$ $4f^{10}$) forming W$^{17+}$. At low electron-ion collision energies, the merged-beam rate coefficient ... More
Electron-ion Recombination of Fe XII forming Fe XI: Laboratory Measurements and Theoretical CalculationsApr 27 2012We have measured electron-ion recombination for Fe XII forming Fe XI using a merged beams configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. The measured merged beams recombination ... More
Dielectronic recombination data for dynamic finite-density plasmas I. Goals and methodologyApr 15 2003A programme is outlined for the assembly of a comprehensive dielectronic recombination database within the generalized collisional--radiative (GCR) framework. It is valid for modelling ions of elements in dynamic finite-density plasmas such as occur in ... More
Ionisation state, excited populations and emission of impurities in dynamic finite density plasmas. I: The generalised collisional-radiative model for light elementsNov 18 2005The paper presents an integrated view of the population structure and its role in establishing the ionisation state of light elements in dynamic, finite density, laboratory and astrophysical plasmas. There are four main issues, the generalised collisional-radiative ... More
Dielectronic Recombination in Photoionized Gas. II. Laboratory Measurements for Fe XVIII and Fe XIXMar 12 1999In photoionized gases with cosmic abundances, dielectronic recombination (DR) proceeds primarily via nlj --> nl'j' core excitations (Dn=0 DR). We have measured the resonance strengths and energies for Fe XVIII to Fe XVII and Fe XIX to Fe XVIII Dn=0 DR. ... More
Dielectronic Recombination of Ground-State and Metastable Li+ IonsJul 19 1999Dielectronic recombination has been investigated for Delta-n = 1 resonances of ground-state Li+(1s^2) and for Delta-n = 0 resonances of metastable Li+(1s2s ^3S). The ground-state spectrum shows three prominent transitions between 53 and 64 eV, while the ... More
Electron-ion Recombination of Fe X forming Fe IX and of Fe XI forming Fe X: Laboratory Measurements and Theoretical CalculationsApr 01 2009We have measured electron-ion recombination for Fe$^{9+}$ forming Fe$^{8+}$ and for Fe$^{10+}$ forming Fe$^{9+}$ using merged beams at the TSR heavy-ion storage-ring in Heidelberg. The measured merged beams recombination rate coefficients (MBRRC) for ... More
Dielectronic Recombination (via N=2 --> N'=2 Core Excitations) and Radiative Recombination of Fe XX: Laboratory Measurements and Theoretical CalculationsAug 02 2001We have measured the resonance strengths and energies for dielectronic recombination (DR) of Fe XX forming Fe XIX via N=2 --> N'=2 (Delta_N=0) core excitations. We have also calculated the DR resonance strengths and energies using AUTOSTRUCTURE, HULLAC, ... More
Recombination of open-f-shell tungsten ionsFeb 11 2017We review experimental and theoretical efforts aimed at a detailed understanding of the recombination of electrons with highly-charged tungsten ions characterised by an open 4f sub-shell. Highly-charged tungsten occurs as a plasma contaminant in ITER-like ... More
Dielectronic Recombination of Fe XV forming Fe XIV: Laboratory Measurements and Theoretical CalculationsApr 06 2007We have measured resonance strengths and energies for dielectronic recombination (DR) of Mg-like Fe XV forming Al-like Fe XIV via N=3 -> N' = 3 core excitations in the electron-ion collision energy range 0-45 eV. All measurements were carried out using ... More
Free expansion of lowest Landau level states of trapped atoms: a wavefunction microscopeJun 13 2003Aug 05 2003We show that for any lowest-Landau-level state of a trapped, rotating, interacting Bose gas, the particle distribution in coordinate space in a free expansion (time of flight) experiment is related to that in the trap at the time it is turned off by a ... More
Parton Distributions in Nucleon on the Basis of a Relativistic Independent Quark ModelAug 28 2001At a low resolution scale with $Q^2={\mu}^2$ corresponding to the nucleon bound state; deep inelastic unpolarized structure functions $F_1(x,{\mu}^2)$ and $F_2(x,{\mu}^2)$ are derived with correct support using the symmetric part of the hadronic tensor ... More
Synthesis and study of alpha-Fe1.4Ga0.6O3: An advanced Ferromagnetic SemiconductorApr 11 2011We report the synthesis of alpha-Fe1.4Ga0.6O3 compound and present its structural phase stability and interesting magnetic, dielectric and photo-absorption properties. In our work Ga doped alpha-Fe2O3 samples are well stabilized in alpha phase (rhombohedral ... More
Unconventional relaxation in antiferromagnetic CoRh$_2$O$_4$ nanoparticlesOct 17 2006Magnetic relaxation in antiferromagnetic CoRh$_2$O$_4$ nanoparticles is investigated at 2 K by cooling the sample from a temperature (70 K) well above the antiferromagnetic ordering temperature at 27 K, following zero field cooled (ZFC) and field cooled ... More
New Patterns of Natural R-Parity Violation with Supersymmetric Gauged FlavorJan 16 2013We point out that supersymmetric gauged flavor models provide a realization of R-parity violation (RPV) that is natural in the sense that it does not lead to catastrophic proton decay for natural values of parameters in the theory. Within specific realizations ... More
Testing leptonic SU(2) horizontal symmetry using neutrino mixingsJul 31 2002Aug 14 2002After some preliminary arguments suggesting that neutrino mixings with inverted mass pattern may be easier to understand within the framework of a local horizontal symmetry SU(2)_H acting on leptons, we construct a specific extension of the minimal supersymmetric ... More
Bimaximal Neutrino Mixixing from a Local SU(2) Horizontal SymmetryJul 08 2002Aug 08 2002Freedom from global anomalies in the presence of a local SU(2)_H horizontal symmetry under which right handed charged leptons transform nontrivially requires that there be at least two right handed neutrinos with masses of order of the horizontal symmetry ... More
Radiatively Induced Type II seesaw and Vector-like 5/3 Charge QuarksJun 26 2013Understanding small neutrino masses in type II seesaw models with TeV scale SM triplet Higgs bosons requires that its coupling with the standard model Higgs doublet H be dialed down to be order eV to KeV, which is a fine-tuning by a factor of $10^{-11}-10^{-8}$ ... More
Re-entrant spin glass and magnetoresistance in Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxideAug 21 2002We have investigated the static and dynamic response of magnetic clusters in Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide, where a sequence of magnetic phase transitions, i.e., paramagnetic (PM) to ferromagnetic at T_{C} $\leq$ 270K and ferromagnetic ... More
Upper bound on the $W_R$ mass in automatically R-conserving SUSY modelsSep 08 1995We show that in automatically R-conserving minimal SUSY left-right symmetric models there is a theoretical upper limit on the mass of the right-handed $W_R$ boson given by $M_{W_R}\leq g M_{SUSY}/f$, where $M_{SUSY}$ is the scale of supersymmetry breaking, ... More
The Bethe Ansatz for Z_S Orbifolds of N=4 Super Yang-Mills TheoryOct 24 2005Worldsheet techniques can be used to argue for the integrability of string theory on AdS_5xS^5/Z_S, which is dual to the strongly coupled Z_S-orbifold of N=4 SYM. We analyze the integrability of these field theories in the perturbative regime and construct ... More
A four-year baseline Swift study of enigmatic X-ray transients located near the Galactic centerJul 01 2010Oct 01 2010We report on continued monitoring observations of the Galactic center carried out by the X-ray telescope aboard the Swift satellite in 2008 and 2009. This campaign revealed activity of the five known X-ray transients AX J1745.6-2901, CXOGC J174535.5-290124, ... More
Noise Analysis and Detection Based on RF Energy Duration in wireless LANOct 11 2011Noise is the major problem while working with wireless LAN. In this paper we analyze the noise by using active receiving antenna and also propose the detection mechanism based on RF energy duration. The standard back off mechanism of 802.11 wireless LAN ... More
Dynamic Quantized Fracture MechanicsApr 20 2005A new quantum action-based theory, Dynamic Quantized Fracture Mechanics (DQFM), is presented that modifies continuum-based dynamic fracture mechanics. The crack propagation is assumed as quantized in both space and time. The static limit case corresponds ... More
A Note on Genome Organisation in RNA Viruses with Icosahedral SymmetryNov 06 2006The structural organisation of the viral genome within its protein container, called the viral capsid, is an important aspect of virus architecture. Many single-stranded (ss) RNA viruses organise a significant part of their genome in a dodecahedral cage ... More
Extended solutions of the harmonic map equation in the special unitary groupApr 15 2013We classify all harmonic maps of finite uniton number from a Riemann surface into SU(n) in terms of certain pieces of the Bruhat decomposition of the subgroup of algebraic loops in SU(n). We give a description of the "Frenet frame data" for such harmonic ... More
Self - Interaction Force for the Particle in the Cone Space - TimeMar 30 1994The force acting on the charged particle moving along an arbitrary trajectory near the straight cosmic string is calculated. This interaction leads to the scattering of particles by the cosmic string. The scattering cross section is considered.
KKM-type theorems for products of simplices and cutting sets and measures by straight linesSep 03 2009In this paper a version of Knaster-Kuratowski-Mazurkiewicz theorem for products of simplices is formulated. Some corollaries for measure partition in the plane and cutting families of sets in the plane by lines are given.
The hard X-ray view of bright infrared galaxiesFeb 09 2009Aims. The synthesis of the cosmic X-ray background (CXB) requires a large population of Compton-thick active galactic nuclei that have not been detected so far. We probe whether bright infrared galaxies could harbor a population of Compton-thick nuclei ... More
Refined Astrometry and Positions for 179 Swift X-ray AfterglowsNov 01 2006Dec 22 2006We present a refined catalog for the positions of 179 Gamma-ray burst (GRB) X-ray afterglows observed by the X-ray Telescope (XRT) on Swift prior to November 1, 2006. The positions are determined by detecting X-ray field sources in the deep X-ray images ... More
The origin of long-period X-ray pulsarsNov 14 2006Nov 22 2006Several relatively bright, persistent X-ray sources display regular pulses, with periods in the range of 700-10000 s. These sources are identified with massive close binaries in which a neutron star accretes material onto its surface. The observed pulsations ... More
Neutron-Anti-Neutron Oscillation: Theory and PhenomenologyFeb 05 2009The discovery of neutrino masses has provided strong hints in favor of the possibility that B-L symmetry is an intimate feature of physics beyond the standard model. I discuss how important information about this symmetry as well as other scenarios for ... More
Massive Neutrinos as Probe of Higher UnificationJun 17 1993There are strong indications for neutrino masses and mixings in the data on solar neutrinos as well as in the observed deficit of muon neutrinos from the atmosphere. The COBE data and other analysis of the large scale structure in the Universe also seems ... More
Minimal SO(10) Grand Unification: Predictions for Proton Decay and Neutrino Masses and Mixings:Oct 11 1993Prospects for SO(10) as a minimal grand unification group have recently been heightened by several considerations such as the MSW resolution of the solar neutrino puzzle, baryogenesis, possibility for understanding fermion masses etc. I review the present ... More
Invariants of links with flat connections in their complements.II. Holonomy R-matrices related to quantized universal enveloping algebras at roots of 1Feb 21 2002Holonomy R-matrices parametrized by finite-dimensional representations are constructed for quantized universal enveloping algebras of simple Lie algebras at roots of 1.
Pulsar timing and its applicationsJan 12 2018Pulsars are remarkably precise "celestial clocks" that can be used to explore many different aspects of physics and astrophysics. In this article I give a brief summary of pulsar properties and describe some of the applications of pulsar timing, including ... More
Little-used Mathematical Structures in Quantum Mechanics II. Representations of the CCR and SuperseparabilityJan 24 2012It often goes unnoticed that, even for a finite number of degrees of freedom, the canonical commutation relations have many inequivalent irreducible unitary representations; the free particle and a particle in a box provide examples that are both simple ... More
Little-used Mathematical Structures in Quantum Mechanics I. Galilei Invariance and the welcher Weg ProblemJan 24 2012Results of the welcher Weg experiment of Duerr, Nonn and Rempe are explained by using ray representations of the Galilei group. The key idea is that the state of the incoming atom be regarded as belonging to an irreducible unitary ray representation of ... More
Solitary Waves of Planar Ferromagnets and the Breakdown of the Spin-Polarized Quantum Hall EffectJan 15 1998A branch of uniformly-propagating solitary waves of planar ferromagnets is identified. The energy dispersion and structures of the solitary waves are determined for an isotropic ferromagnet as functions of a conserved momentum. With increasing momentum, ... More
Note on the Curvature and Index of Almost Unitary Contraction OperatorJul 28 2000Dec 04 2000In the recent preprint (OA/0006224) S. Parrott proved the equality between the Arveson`s curvature and the Fredholm index of a "pure" contraction with finite defect numbers. In the present note one derives a similar formula in the "non-pure" case.
The genus and the category of configuration spacesMay 05 2009Jul 16 2009In this paper configuration spaces of smooth manifolds are considered. The accent is made on actions of certain groups (mostly $p$-tori) on this spaces by permuting their points. For such spaces the cohomological index, the genus in the sense of Krasnosel'skii-Schwarz, ... More
Calculating multiloop integrals using dimensional recurrence relation and D-analyticityJul 14 2010We review the method of the calculation of multiloop integrals recently suggested in Ref.[Lee2010]. A simple method of derivation of the dimensional recurrence relation suitable for automatization is given. Some new analytic results are given.
Regular embeddings of manifolds and topology of configuration spacesJun 03 2010Jun 28 2011For a topological space $X$ we study continuous maps $f : X\to \mathbb R^m$ such that images of every pairwise distinct $k$ points are affinely (linearly) independent. Such maps are called affinely (linearly) $k$-regular embeddings. We investigate the ... More
A measure of non-convexity in the plane and the Minkowski sumMay 07 2010In this paper a measure of non-convexity for a simple polygonal region in the plane is introduced. It is proved that for "not far from convex" regions this measure does not decrease under the Minkowski sum operation, and guarantees that the Minkowski ... More
$Z_2$-index of the grassmanian $G_{2n}^n$Jun 11 2010We study the real Grassmann manifold $G_{2n}^n$ (of $n$-subspaces in $\mathbb R^{2n}$), and the action of $Z_2$ on it by taking the orthogonal complement. The homological index of this action is estimated from above and from below. In case $n$ is a power ... More
Aspects of the zero $Λ$ limit in the AdS/CFT correspondenceNov 28 2013Nov 18 2014We examine the correspondence between QFT observables and bulk solutions in the context of AdS/CFT in the limit as the cosmological constant $\Lambda \to 0$. We focus specifically on the spacetime metric and a non-backreacting scalar in the bulk, compute ... More
Theorems of Borsuk-Ulam type for flats and common transversalsMay 17 2009Nov 25 2009In this paper some results on the topology of the space of $k$-flats in $\mathbb R^n$ are proved, similar to the Borsuk-Ulam theorem on coverings of sphere. Some corollaries on common transversals for families of compact sets in $\mathbb R^n$, and on ... More
On finite-sheeted covering mappings onto solenoidsDec 15 2003We study limit mappings from a solenoid onto itself. It is shown that each equivalence class of finite-sheeted covering mappings from connected topological spaces onto a solenoid is determined by a limit mapping. Properties of periodic points of limit ... More
Entanglement between distant qubits in cyclic XX chainsJun 04 2009We evaluate the exact concurrence between any two spins in a cyclic XX chain of n spins placed in a uniform transverse magnetic field, both at zero and finite temperature, by means of the Jordan-Wigner transformation plus a number parity projected statistics. ... More
A peculiar thermonuclear X-ray burst from the transiently accreting neutron star SAX J1810.8-2609Oct 25 2012We report on a thermonuclear (type-I) X-ray burst that was detected from the neutron star low-mass X-ray binary SAX J1810.8-2609 in 2007 with Swift. This event was longer (~20 min) and more energetic (a radiated energy of Eb~6.5E39 erg) than other X-ray ... More
Cepheids as Distance IndicatorsNov 04 1996We review the use of Cepheids as distance indicators with particular emphasis on the methods which have been applied to HST observations of Cepheids. The calibration of the period-luminosity relations is examined in detail and we identify possible problems ... More
Method for reducing of noise by improving signal-to-noise-ratio in wireless LANOct 11 2011The signal to noise ratio (SNR) is one of the important measures for reducing the noise.A technique that uses a linear prediction error filter (LPEF) and an adaptive digital filter (ADF) to achieve noise reduction in a speech and image degraded by additive ... More
Algebraic Exact Solvability of trigonometric-type Hamiltonians associated to root systemsOct 27 1998In this article, we study and settle several structural questions concerning the exact solvability of the Olshanetsky-Perelomov quantum Hamiltonians corresponding to an arbitrary root system. We show that these operators can be written as linear combinations ... More
Uniformly Accelerated Mirrors. Part 2: Quantum CorrelationsSep 18 2002We study the correlations between the particles emitted by a moving mirror. To this end, we first analyze $< T_{\mu\nu}(x) T_{\alpha\beta}(x') >$, the two-point function of the stress tensor of the radiation field. In this we generalize the work undertaken ... More
Connecting bimaximal neutrino mixing to a light sterile neutrinoJul 25 2001Aug 24 2001It is shown that if small neutrino masses owe their origin to the conventional seesaw mechanism and the MNS mixing matrix is in the exact bimaximal form, then there exist symmetries in the theory that allow one of the righthanded neutrinos to become naturally ... More
Origin of neutrino masses and mixingsAug 22 2000Aug 31 2000A brief overview of the important theoretical issues in neutrino physics is presented and some of the current ideas for addressing them in the framework of the seesaw mechanism of neutrino masses are discussed. Among the topics discussed are ways to understand ... More
Sterile NeutrinosMar 04 1999A simultaneous understanding of the results of the LSND experiment indicating $\nu_{\mu}-\nu_e$ oscillation together with other evidences for neutrino oscillations from solar and atmospheric neutrino data seems to require the existence of at least one ... More
Supersymmetric Grand UnificationJan 07 1998Jan 12 1998These lectures begin with a brief introduction to the minimal supersymmetric standard model (MSSM) and the various mechanisms for hidden sector supersymmetry breaking and go on to provide a pedagogical discussion of the various kinds of supersymmetric ... More
Neutrino Mass Textures and the Nature of New Physics Implied by Present Neutrino DataFeb 03 1997If all indications for neutrino oscillations observed in the solar, atmospheric neutrino data as well as in the LSND experiments are borne out by the ongoing and future experiments, then they severely constrain the neutrino mass texture. In particular, ... More
Particle Physics Implications of Neutrinoless Double Beta DecayAug 10 1998Aug 14 1998Neutrinoless double beta decay is a sensitive probe of the patterns of neutrino masses and mixings if the neutrinos are Majorana particles as well as other new physics scenarios beyond the standard model. In this talk, the present experimental lower bound ... More
Supersymmetric Left-Right Model, Automatic R-parity Conservation and Constraints on the $W_R$ MassJun 29 1998Supersymmetric left-right models with the see-saw mechanism for the neutrino masses have the attractive property that they conserve baryon and lepton number exactly in the Lagrangian. In this talk, I review the recent results valid for a large class of ... More
Neutrino Physics in a Muon colliderNov 24 1997Dec 19 1997A muon collider is expected to produce a high intensity neutrino beam which is an admixture of either $\nu_{\mu}+\bar{\nu_e}$ or $\bar{\nu}_{\mu} +\nu_e$ which can can be directed to underground detectors far away from the source. It will not only allow ... More