#### Sample records for amplitude proportional coulomb

1. Optimal Tuning of Amplitude Proportional Coulomb Friction Damper for Maximum Cable Damping

DEFF Research Database (Denmark)

Weber, Felix; Høgsberg, Jan Becker; Krenk, Steen

2010-01-01

spillover to higher modes evoked by the amplitude proportional Coulomb friction damper which clamps the cable at its upper and lower positions. The resulting nonsinusoidal cable motion clearly violates the assumption of pure harmonic motion and explains why such dampers have to be tuned differently from...... damper via harmonic averaging. It turns out that the friction force level has to be adjusted in proportion to cable amplitude at damper position which is realized by amplitude feedback in real time. The performance of this adaptive damper is assessed by simulated free decay curves from which the damping...

2. Exact solution to the Coulomb wave using the linearized phase-amplitude method

Directory of Open Access Journals (Sweden)

Shuji Kiyokawa

2015-08-01

Full Text Available The author shows that the amplitude equation from the phase-amplitude method of calculating continuum wave functions can be linearized into a 3rd-order differential equation. Using this linearized equation, in the case of the Coulomb potential, the author also shows that the amplitude function has an analytically exact solution represented by means of an irregular confluent hypergeometric function. Furthermore, it is shown that the exact solution for the Coulomb potential reproduces the wave function for free space expressed by the spherical Bessel function. The amplitude equation for the large component of the Dirac spinor is also shown to be the linearized 3rd-order differential equation.

3. Amplitude Function of Asymptotic Correlations Along Charged Wall in Coulomb Fluids

Science.gov (United States)

2016-05-01

In classical semi-infinite Coulomb fluids, two-point correlation functions exhibit a slow inverse-power law decay along a uniformly charged wall. In this work, we concentrate on the corresponding amplitude function which depends on the distances of the two points from the wall. Recently Šamaj (J Stat Phys 161:227-249 2015), applying a technique of anticommuting variables to a 2D system of charged rectilinear wall with "counter-ions only", we derived a relation between the amplitude function and the density profile which holds for any temperature. In this paper, using the Möbius conformal transformation of particle coordinates in a disc, a new relation between the amplitude function and the density profile is found for that model. In all exactly solvable cases, the amplitude function factorizes itself in the two distances from the wall. Presupposing this factorization property at any temperature and using specific sum rules for semi-infinite geometries, a relation between the amplitude function of the charge-charge structure function and the charge profile is derived for many-component Coulomb fluids in any dimension.

4. Amplitude Function of Asymptotic Correlations Along Charged Wall in Coulomb Fluids

Science.gov (United States)

2016-07-01

In classical semi-infinite Coulomb fluids, two-point correlation functions exhibit a slow inverse-power law decay along a uniformly charged wall. In this work, we concentrate on the corresponding amplitude function which depends on the distances of the two points from the wall. Recently Šamaj (J Stat Phys 161:227-249 2015), applying a technique of anticommuting variables to a 2D system of charged rectilinear wall with "counter-ions only", we derived a relation between the amplitude function and the density profile which holds for any temperature. In this paper, using the Möbius conformal transformation of particle coordinates in a disc, a new relation between the amplitude function and the density profile is found for that model. In all exactly solvable cases, the amplitude function factorizes itself in the two distances from the wall. Presupposing this factorization property at any temperature and using specific sum rules for semi-infinite geometries, a relation between the amplitude function of the charge-charge structure function and the charge profile is derived for many-component Coulomb fluids in any dimension.

5. Magnitudes and slopes of real and imaginary amplitudes in the Coulomb interference region of pp and pbarp scattering

International Nuclear Information System (INIS)

Full text: We use exact Derivative Dispersion Relations [?, ?] to investigate properties of the real and imaginary amplitudes in the forward region of pp and pbarp scattering. We emphasize that the effective slope in dσ/dt is formed by different exponential slopes in the real and imaginary amplitudes (called BR and BI ). For this purpose a more general treatment of the Coulomb phase is developed. The dσ/dt data in the range from 19 to 1800 GeV for low |t| are analysed in terms of the four quantities σ, ρ, BI, BR that are basic for dynamical models . The usual assumption that BI and BR are the same, with σ not depending strongly on t, does not agree with dispersion relations, for which BR > BI , and with the expectation that the first real zero approaches t=0 as the energy increases. Our work uses dispersion relations to disentangle the quantities that represent observables in terms of imaginary and real parts, intrinsically combined with the Coulomb contribution. To investigate real slopes we use new forms of dispersion relations [?]. With the difference between imaginary and real slopes , the future RHIC and LHC data will require the extended analysis with BR as a free quantity. We investigate in detail the region from 19 to 30 GeV where the real amplitude in pp scattering may vanish. The data for ρ are contradictory in this range. We investigate the meaning of the real slope BR in this region where the parameter ρ is very small, and construct coherent description of the data. In the high energy region we obtain scattering parameters for the RHIC and LHC experiments. (author)

6. Three-particle Coulomb on-shell vertex functions. Behaviour of amplitude of simultaneous transfer reaction of two charged particles in the vicinity of the nearest singularity in cos0

International Nuclear Information System (INIS)

The connection of the on-shell function with the asymptotical coefficient of the three-particle wave functtion of the bound system in a configuration space is found. The expression for the leading singularity term of the exact amplitude of sub-Coulomb reactions is found in the vicinity of the nearest singularity

7. Use of Dirac-Coulomb Sturmians of the first order for relativistic calculations of two-photon bound-bound transition amplitudes in hydrogen-like ions

International Nuclear Information System (INIS)

A fully relativistic treatment of the S-matrix elements describing two-photon bound-bound transition amplitudes in hydrogen-like ions is undertaken in the present work. Several selected transitions from the ground state vertical bar 12S) towards the L and M shells (vertical bar 22S), vertical bar 32S), vertical bar 32D3/2) and vertical bar 32D5/2)) are described. For that purpose, we use the complete set of relativistic Sturmian functions derived by Szmytkowski (1997 J. Phys. B: At. Mol. Opt. Phys. 30 825) from the first-order Sturm-Liouville problems for the Dirac equation. The method followed consists of writing the matrix elements in terms of Green functions expanded over the first-order Dirac-Coulomb Sturmians. Previous approaches used a Sturmian basis associated with the Gell-Mann-Feynman equation. On the other hand, a distinctive feature of our tensor treatment is that the expressions derived are quite general and could be applied to any multipole of the two-photon bound-bound transitions. In the case of dipole transitions, considered also by Szymanowski et al (1997 Phys. Rev. A 56 700) in their calculations, the selection rules derived from our method lead to two additional terms related to l1p = 2 and l2p = 2. The numerical results obtained for the transition from the ground state |12S) towards the L and M shells enable us to draw inferences as to the improvements of our method

8. Proportionality lost - proportionality regained?

DEFF Research Database (Denmark)

Werlauff, Erik

often cannot be done without thorough knowledge of the particular legal field in which the case is anchored, and the ECJ is often left to flounder somewhat on this, with the result that we are suddenly faced with the Court’s acceptance of a restriction. The difficulty often lies - not in recognising the...... restriction, but in testing its proportionality. The article illustrates its point by referring to two categories of decision: (A) proportionality-strong decisions, which illustrate a thorough and firm proportionality assessment, and (B) proportionality-weak decisions, which could have led to a different...... result if the proportionality argument had been based on adequate insight. Proportionality-weak decisions are in the article be categorised as: (1) Cases in which the ECJ allows itself to be “talked into” accepting a restriction, and for which the question of proportionality actually has been considered...

9. Influence of the coulomb vertex effects on peripheral partial wave amplitudes in the mechanism of successive two-proton transfer in the peripheral nuclear A(X,Y)B reaction induced by weakly bound light nuclei at low energies

International Nuclear Information System (INIS)

Full text: In the present work the peripheral two-proton (p1 and p2) transfer A(X,Y)B reaction induced by weakly bound light nuclei at low energies is considered. Herein X = ((Yp2 ) +p1) and B = ((Ap1)+p2). We consider the case when the proton p1(p2) is loosely bound in the nucleus X (B) with the binding energy εX (εB) and the binding energies of the protons p2 and p1, ε(Yp2) and ε(Yp1), in the bound (Yp2 ) and (Ap1) states, respectively, satisfy the conditions ε(Yp2) >>εX, ε(Yp1)>>εB, εX ≅εB. One of the main mechanisms of the investigated reaction corresponds to that, the amplitude of which is described by the square diagram. We have taken into account the fact that the main contribution to the amplitude of that reaction comes from the peripheral partial-wave amplitudes (l>>1), which are determined by the nearest to the physical region -1≤ cosθ≤ 1 singular point cosθ = ζ >1 ( θ is the scattering angle in the c.m.s.). In the case under consideration, the nearest singular point corresponds to the singularity of the Coulomb vertex form factors for the virtual decays X→(Yp2)+p1 and (Ap1)+p2→B (an anomalous mechanism).The explicit forms of the peripheral partial-wave amplitudes Ml (l>>1), which are determined by this singularity, as well as the peripheral partial-wave amplitudes MIDWBA corresponding to the same mechanism of the successive transfer within the conventional DWBA (a usual mechanism), have been found. One notes that the behavior of MIDWBA is determined by the singularity ζp, and ζp>ζ since a value of ζp is determined by the binding energies of εX and ε(Yp2). The asymptotic expressions for Ml and MIDWBA for l>>1 show the different dependence on l. Besides, the explicit forms of the exact amplitude at cosθ→ζ and the singular part of the amplitude corresponding to the usual mechanism of DWBA at cosθ→ζp have been derived. Investigation of analytic properties of the amplitudes of the peripheral transfer reactions 6Li(12N,10B

10. Coulomb-Blockade Oscillations in Semiconductor Nanostructures

OpenAIRE

Houten, van, H.; Beenakker, C. W. J.; Staring, A.A.M.

2005-01-01

I. Introduction (Preface, Basic properties of semiconductor nanostructures). II. Theory of Coulomb-blockade oscillations (Periodicity of the oscillations, Amplitude and lineshape). III. Experiments on Coulomb-blockade oscillations (Quantum dots, Disordered quantum wires, Relation to earlier work on disordered quantum wires). IV. Quantum Hall effect regime (The Aharonov-Bohm effect in a quantum dot, Coulomb blockade of the Aharonov-Bohm effect, Experiments on quantum dots, Experiments on disor...

11. Proportional reasoning

DEFF Research Database (Denmark)

Dole, Shelley; Hilton, Annette; Hilton, Geoff;

2015-01-01

Proportional reasoning is widely acknowledged as a key to success in school mathematics, yet students’ continual difficulties with proportion-related tasks are well documented. This paper draws on a large research study that aimed to support 4th to 9th grade teachers to design and implement tasks...... to foster students’ proportional reasoning. Classroom data revealed limited initial teacher knowledge and awareness of the pervasive nature of proportional reasoning required in the mathematics curriculum. Teacher capacity to seize teachable moments for building students’ proportional reasoning...... skills increased throughout the project. From this background, this paper presents an analysis of the proportional reasoning demands and opportunities of topics within the school mathematics curriculum in Australia. Implications for the study of whole number arithmetic (WNA) and other topics to promote...

12. Formatting of specific protective measures and proportion of cognition scope Formatação de tutelas específicas e dosagem da amplitude da cognição

Directory of Open Access Journals (Sweden)

Odoné Serrano Júnior

2008-01-01

Full Text Available This study starts from the premise that civil protective measures are the expression of the fundamental right to protection, and require the use of the best available technique in the current state of art. Its article will show that formatting techniques of specific protective measures, implemented by combining preventive measures and means for their effectiveness, adapted to the concrete needs of the right in need of protection, and added to the technique of correct proportion of legal cognition scope, contribute for the rationalization of the legal activity. Consequently, such techniques simplify and accelerate the procedure, causing gains in terms of effectiveness.Partindo do pressuposto de que a tutela jurisdicional civil é expressão do direito fundamental de proteção, que exige o emprego da melhor técnica disponível no atual estado da arte, mostrar-se-á que as técnicas de formatação de tutelas específicas, implementadas a partir da possibilidade de combinação de provimentos e dos seus meios de efetivação, adequando-se às necessidades concretas do direito carente de tutela, somada à técnica da dosagem correta da amplitude da cognição judicial, contribuem sobremaneira para a racionalização da atividade jurisdicional, simplificando e acelerando o procedimento, importando, enfim, em ganhos em termos de efetividade.

13. Coulomb-nucleon phase and spin effects in the diffraction dip domain

International Nuclear Information System (INIS)

The total phase of the Coulomb-hadron interaction is calculated with the true hadron scattering amplitude and with the Coulomb amplitude including the form factor of hadrons. This phase includes also the contribution of the phase of the pure coulomb interaction of hadrons taking into account the hadron form factors. The analyzing power AN is calculated in the whole diffraction dip domain of high-energy elastic hadron scattering with the Coulomb-hadron interference effects. (author)

14. Coulomb Energy of Nuclei

OpenAIRE

Shaginyan, V. R.

2002-01-01

The density functional determining the Coulomb energy of nuclei is calculated to the first order in $e^2$. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CC...

15. Ion Coulomb Crystals

CERN Document Server

Thompson, Richard C

2014-01-01

Ion Coulomb crystals (ICC), formed by atomic ions at low temperatures in radiofrequency and Penning ion traps, are structures that have remarkable properties and many applications. Images of Coulomb crystals are striking and reveal the crystal structure, which arises from a balance between the trapping forces acting on the ions and their mutual Coulomb repulsion. Applications of these structures range from frequency standards and quantum simulation through to measurement of the cross sections of chemical reactions of ions.

16. Coulomb energy of nuclei

International Nuclear Information System (INIS)

The density functional determining the Coulomb energy of nuclei is calculated to the first order in e2. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CCE is shown to come from the surface region of nuclei. The CCE effect on the calculated proton drip line is examined, and the maximum charge Z of nuclei near this line is found to decrease by 2 or 3 units. The effect of Coulomb interaction on the effective proton mass is analyzed

17. Coulomb Energy of Nuclei

CERN Document Server

Shaginyan, V R

2001-01-01

The density functional determining the Coulomb energy of nuclei is calculated to the first order in $e^2$. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CCE is shown to come from the surface region of nuclei. The CCE effect on the calculated proton drip line is examined, and the maximum charge $Z$ of nuclei near this line is found to decrease by 2 or 3 units. The effect of Coulomb interaction on the effective proton mass is analyzed.

Energy Technology Data Exchange (ETDEWEB)

Greensite, J.; Olejnik, S.

2003-09-26

We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.

International Nuclear Information System (INIS)

We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.

20. Coulomb Drag in Graphene

OpenAIRE

Tse, Wang-Kong; Hu, Ben Yu-Kuang; Sarma, S. Das

2007-01-01

We study the Coulomb drag between two single graphene sheets in intrinsic and extrinsic graphene systems with no interlayer tunneling. The general expression for the nonlinear susceptibility appropriate for single-layer graphene systems is derived using the diagrammatic perturbation theory, and the corresponding exact zero-temperature expression is obtained analytically. We find that, despite the existence of a non-zero conductivity in an intrinsic graphene layer, the Coulomb drag between int...

1. Three-body processes in the presence of Coulomb forces

International Nuclear Information System (INIS)

Rigorous definitions are provided for the scattering amplitudes describing elastic, inelastic and rearrangement reactions of one charged particle and a bound state of two other charged bodies, and of break-up amplitudes with one neutral and two charged particles. The resulting expressions confirm, and give precise meaning to, what is intuitively anticipated in conventional approaches. Furthermore, integral equations for these transition amplitudes are available which render feasible practical calculations of Coulomb corrections in three-particle reactions. 2 references

2. Positron scattering from hydrogen atom with screened Coulomb potentials

International Nuclear Information System (INIS)

Elastic positron-hydrogen collisions with screened Coulomb potentials have been investigated using a second-order distorted wave Born approximation in the momentum space. Two types of potentials have been considered, namely, static screened Coulomb potential and exponential cosine-screened Coulomb potential. Using a simple variationally determined hydrogenic wave function it has been possible to obtain the scattering amplitude in a closed form. A detailed study has been made on the differential and total cross sections in the energy range 20–300 eV

3. Characteristics of Coulomb fission

OpenAIRE

Oberacker, Volker; Greiner, Walter; Kruse, Hans; Pinkston, William T.

2006-01-01

Within an extended semiquantal theory we perform large-sized coupled-channel calculations involving 260 collective levels for Coulomb fission of 238U. Differential Coulomb fission cross sections are studied as a function of bombarding energy and impact parameter for several projectiles. In the Xe + U case, total cross sections are also given. We find a strong dependence on projectile charge number, PCF(180°)∼(Zp)6 in the region 50≤Zp≤92 for a fixed ratio E/ECoul, which might...

4. Holographic Coulomb branch vevs

CERN Document Server

Skenderis, K; Skenderis, Kostas; Taylor, Marika

2006-01-01

We compute holographically the vevs of all chiral primary operators for supergravity solutions corresponding to the Coulomb branch of N=4 SYM and find exact agreement with the corresponding field theory computation. Using the dictionary between 10d geometries and field theory developed to extract these vevs, we propose a gravity dual of a half supersymmetric deformation of N=4 SYM by certain irrelevant operators.

5. Coulomb drag in graphene

OpenAIRE

Hwang, E. H.; Sarma, S. Das

2011-01-01

We calculate theoretically the Coulomb drag resistivity for two graphene monolayers spatially separated by a distance "$d$". We show that the frictional drag induced by inter-layer electron-electron interaction goes asymptotically as $T^2/n^3$ and $T^2 \\ln(n)/n$ in the high-density ($k_F d \\gg 1$) and low-density ($k_F d \\ll 1$) limits, respectively.

6. Coulomb drag in topological insulator films

Science.gov (United States)

Liu, Hong; Liu, Weizhe Edward; Culcer, Dimitrie

2016-05-01

We study Coulomb drag between the top and bottom surfaces of topological insulator films. We derive a kinetic equation for the thin-film spin density matrix containing the full spin structure of the two-layer system, and analyze the electron-electron interaction in detail in order to recover all terms responsible for Coulomb drag. Focusing on typical topological insulator systems, with a film thicknesses d up to 6 nm, we obtain numerical and approximate analytical results for the drag resistivity ρD and find that ρD is proportional to T2d-4 na-3/2 np-3/2 at low temperature T and low electron density na,p, with a denoting the active layer and p the passive layer. In addition, we compare ρD with graphene, identifying qualitative and quantitative differences, and we discuss the multi-valley case, ultra thin films and electron-hole layers.

7. On Calculation of Amplitudes in Quantum Electrodynamics

OpenAIRE

Karplyuk, Kostyantyn; Zhmudsky, Oleksandr

2012-01-01

A new method of calculation of amplitudes of different processes in quantum electrodynamics is proposed. The method does not use the Feynman technique of trace of product of matrices calculation. The method strongly simplifies calculation of cross sections for different processes. The effectiveness of the method is shown on the cross-section calculation of Coulomb scattering, Compton scattering and electron-positron annihilation.

8. Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation

Energy Technology Data Exchange (ETDEWEB)

Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

1998-03-01

In the Coulomb excitation of {sup 155}Gd with heavy projectiles, {sup 32}S, {sup 58}Ni and {sup 90}Zr, unexpectedly large enhancement of a positive-parity side band has been observed. This enhancement could not be reproduced by a Coulomb-excitation calculation taking into account the recommended upper limits of E1 or E3 transitions, which are compiled in the whole mass region, and is proportional to the electric field accomplished in the Coulomb-scattering process. (author)

9. Coulomb pair-creation

International Nuclear Information System (INIS)

Electron-positron pair production in strong Coulomb fields is outlined. It is shown that the singular behaviour of the adiabatic basis can be removed if solutions of the time dependent external field Dirac equation are used as a basis to expand the fermion field operator. This latter 'asymptotic basis' makes it possible to introduce Feynman-propagator. Applying the reduction technique, the computation of all of the basic quantities can be reduced to the solution of an integral equation. The positron spectrum for separable potential model with Lorentzian time dependence and for potential jump is analyzed in the pole approximation. (author)

10. The Principle of Proportionality

DEFF Research Database (Denmark)

Bennedsen, Morten; Meisner Nielsen, Kasper

2005-01-01

Recent policy initiatives within the harmonization of European company laws have promoted a so-called "principle of proportionality" through proposals that regulate mechanisms opposing a proportional distribution of ownership and control. We scrutinize the foundation for these initiatives by...

11. Relativistic Aharonov--Bohm effect in the presence of two-dimensional Coulomb potential

OpenAIRE

2004-01-01

We obtain exact solutions to the Dirac equation and the relevant binding energies in the combined Aharonov--Bohm--Coulomb potential in 2+1 dimensions. By means of solutions obtained the quantum Aharonov--Bohm effect is studied for free and bound electron states. We show that the total scattering amplitude in the combined Aharonov--Bohm--Coulomb potential is a sum of the Aharonov--Bohm and the Coulomb scattering amplitudes. This modifies expression for the standard Aharonov--Bohm cross section...

12. The Coulomb integrals and the diffraction model of transfer reactions

International Nuclear Information System (INIS)

New asymptotic expressions for the Coulomb integrals are derived and compared with numerical results, the Watson asymptotics and the WKB approximations. The analytical expressions for the Coulomb integrals are used in cross section calculations for single-nucleon transfer reactions in the framework of the diffraction model. The case of the zero orbital angular momentum transfer is considered. The interference of the Fresnel and Fraunhofer parts of the reaction amplitude are discused in detail. The undertaken treatment can be useful for the interpretation of the associated experimental data and the results of DWBA calculations. (orig.)

13. The Proportional Set

Science.gov (United States)

Vilella, Cori

2009-09-01

In this paper we deal with asymmetric TU-cooperative games where every player has an initial positive weight. In this framework we introduce a new set-solution concept, the proportional set, which is based on equity considerations. We provide an algorithm to locate the proportional set inspired by Dutta and Ray [3] algorithm's to find the egalitarian solution in a convex game, and we prove that, for superadditive games and for any weights of the players, the proportional set is included in the equity core, see [9]. For convex games the proportional set has only one element and it is in the core of the game. In the particular case of convex games where all players have the same weight the proportional algorithm coincides with the one given by Dutta and Ray [3] and the solution is the egalitarian solution.

14. Coulomb interactions within halo EFT

International Nuclear Information System (INIS)

Preliminary results of an effective field theory applied to nuclear cluster systems are presented, where Coulomb interactions play a significant role. Presented at the 20th Few-Body Conference, Pisa, Italy, 10-14 September 2007. (author)

15. Hadron diffractive scattering at ultrahigh energies and coulomb interaction

CERN Document Server

Anisovich, V V

2016-01-01

We study the interplay of hadronic and Coulomb interactions for $pp$ scattering at LHC energies on the basis of the previous determination of the real part of the amplitude [{\\it V.V. Anisovich, V.A. Nikonov, J. Nyiri}, Int. J. Mod. Phys. A{\\bf 30}, 1550188 (2015)]. The interference of hadron and Coulomb interactions is discussed in terms of the $K$-matrix function technique. Supposing the black disk mode for the asymptotic interaction of hadrons, we calculate interference effects for the energies right up to $\\sqrt{s}= 10^6$ TeV. It turns out that the real part of the amplitude is concentrated in the impact parameter space at the border of the black disk that results in a growth of interplay effects with the energy increase.

16. Suitability of linear quadrupole ion traps for large Coulomb crystals

OpenAIRE

Tabor, D. A.; Rajagopal, V.; Lin, Y-W.; Odom, B.

2011-01-01

Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial co...

17. Proportional Representation with Uncertainty

OpenAIRE

Francesco De Sinopoli; Giovanna Iannantuoni; Elena Manzoni; Carlos Pimienta

2014-01-01

We introduce a model with strategic voting in a parliamentary election with proportional representation and uncertainty about voters’ preferences. In any equilibrium of the model, most voters only vote for those parties whose positions are extreme. In the resulting parliament, a consensus government forms and the policy maximizing the sum of utilities of the members of the government is implemented.

18. Coulomb explosion of "hot spot"

CERN Document Server

Oreshkin, V I; Chaikovsky, S A; Artyomov, A P

2016-01-01

The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed and estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

19. Coulomb interactions in particle beams

International Nuclear Information System (INIS)

This book develops analytical and computer models for beams in which Coulomb interactions are important. The research into the different phenomena of Coulomb interactions in particle beams is stimulated by developments in the field of electron beam lithography for VLSI electronics. The standard theory of charged particle optics breaks down for intense beams in which interactions between particles are significant. This monograph is devoted to the theory of these intense beams, which are not only used in VLSI electronics but also in scanning electron microscopes. The theory is also applicable to focused ion beams, which are used in VLSI mask repair

20. Renormalization in Coulomb gauge QCD

International Nuclear Information System (INIS)

Research highlights: → The Hamiltonian in the Coulomb gauge of QCD contains a non-linear Christ-Lee term. → We investigate the UV divergences from higher order graphs. → We find that they cannot be absorbed by renormalization of the Christ-Lee term. - Abstract: In the Coulomb gauge of QCD, the Hamiltonian contains a non-linear Christ-Lee term, which may alternatively be derived from a careful treatment of ambiguous Feynman integrals at 2-loop order. We investigate how and if UV divergences from higher order graphs can be consistently absorbed by renormalization of the Christ-Lee term. We find that they cannot.

1. The divine proportion

CERN Document Server

Huntley, H E

1970-01-01

Using simple mathematical formulas, most as basic as Pythagoras's theorem and requiring only a very limited knowledge of mathematics, Professor Huntley explores the fascinating relationship between geometry and aesthetics. Poetry, patterns like Pascal's triangle, philosophy, psychology, music, and dozens of simple mathematical figures are enlisted to show that the ""divine proportion"" or ""golden ratio"" is a feature of geometry and analysis which awakes answering echoes in the human psyche. When we judge a work of art aesthetically satisfying, according to his formulation, we are making it c

2. Entropic Corrections to Coulomb's Law

Science.gov (United States)

Hendi, S. H.; Sheykhi, A.

2012-04-01

Two well-known quantum corrections to the area law have been introduced in the literatures, namely, logarithmic and power-law corrections. Logarithmic corrections, arises from loop quantum gravity due to thermal equilibrium fluctuations and quantum fluctuations, while, power-law correction appears in dealing with the entanglement of quantum fields in and out the horizon. Inspired by Verlinde's argument on the entropic force, and assuming the quantum corrected relation for the entropy, we propose the entropic origin for the Coulomb's law in this note. Also we investigate the Uehling potential as a radiative correction to Coulomb potential in 1-loop order and show that for some value of distance the entropic corrections of the Coulomb's law is compatible with the vacuum-polarization correction in QED. So, we derive modified Coulomb's law as well as the entropy corrected Poisson's equation which governing the evolution of the scalar potential ϕ. Our study further supports the unification of gravity and electromagnetic interactions based on the holographic principle.

3. Electron in the Aharonov-Bohm potential and Coulomb field in (2+1)-dimensions

International Nuclear Information System (INIS)

One derived the precise solutions of the Dirac equation in 2+1 dimensions and determined the electron energy spectrum in the superposition of the Aharonov-Bohm potential and of the Coulomb potential. The expression for the scattering amplitude is presented as a sum of the amplitudes of scattering in the Aharonov-Bohm potential and in the Coulomb potential. The wave function calibration invariant phase or the energy of the electron bound state are shown to be the observed values. One derived a formula for the cross section of the spin-polarized electron scattering in the Aharonov-Bohm potential

4. Bulk and edge quasihole tunneling amplitudes in the Laughlin state

OpenAIRE

Hu, Zi-Xiang; Lee, Ki Hoon; Wan, Xin

2012-01-01

The tunneling between the Laughlin state and its quasihole excitations are studied by using the Jack polynomial. We find a universal analytical formula for the tunneling amplitude, which can describe both bulk and edge quasihole excitations. The asymptotic behavior of the tunneling amplitude reveals the difference and the crossover between bulk and edge states. The effects of the realistic coulomb interaction with a background-charge confinement potential and disorder are also discussed. The ...

5. Treatment versus proportionality

DEFF Research Database (Denmark)

Sorensen, David Woodrow Mattson

2010-01-01

. This critique, which hinges on proportionality, led to a change in the law on July 1, 2000, after which the length of treatment for non-serious-violent crimes was limited to a maximum of five years. This change was itself criticized by the Council of Medical Forensic Specialists, who argued that time...... of release should be based on mental health criteria as opposed to simple time schedules, and that release after five years would not provide adequate time to treat all persons – implying the possibility of a heightened risk of recidivism. The current study compares rates of recidivism among mentally...... disturbed persons sentenced before and after the July 1, 2000 change in the law. The analysis is based on 1510 persons serving 1554 sentences and utilizes data from the criminal register, the central psychiatric register, the cause of death register, and the population register. The data do not support the...

6. Constant Proportion Portfolio Insurance

DEFF Research Database (Denmark)

Jessen, Cathrine

2014-01-01

Portfolio insurance, as practiced in 1987, consisted of trading between an underlying stock portfolio and cash, using option theory to place a floor on the value of the position, as if it included a protective put. Constant Proportion Portfolio Insurance (CPPI) is an option-free variation on the...... theme, originally proposed by Fischer Black. In CPPI, a financial institution guarantees a floor value for the “insured” portfolio and adjusts the stock/bond mix to produce a leveraged exposure to the risky assets, which depends on how far the portfolio value is above the floor. Plain-vanilla portfolio...... insurance largely died with the crash of 1987, but CPPI is still going strong. In the frictionless markets of finance theory, the issuer’s strategy to hedge its liability under the contract is clear, but in the real world with transactions costs and stochastic jump risk, the optimal strategy is less obvious...

7. Coulomb-Born-Oppenheimer approximation in Ps-H scattering

Hasi Ray

2006-02-01

To improve the Coulomb-Born approximation (CBA) theory of ionization in positronium (Ps) and atom scattering, the effect of exchange is introduced. The nine-dimensional exchange amplitude for ionization of Ps in Ps-H scattering is reduced to a two-dimensional integral using the present Coulomb-Born-Oppenheimer approximation (CBOA). The methodology is extremely useful to evaluate ionization parameters for different target systems and for different types of ionization processes. It is then applied to evaluate the Ps-ionization cross-section and to estimate the effect of exchange on Ps-ionization in Ps-H system. We establish the importance of exchange at lower energy region.

8. Renormalization group analysis of graphene with a supercritical Coulomb impurity

CERN Document Server

Nishida, Yusuke

2016-01-01

We develop a field theoretical approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov-Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.

9. Suitability of linear quadrupole ion traps for large Coulomb crystals

CERN Document Server

Tabor, D A; Odom, B

2011-01-01

Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial component of micromotion, which leads to first-order Doppler shifts along the preferred spectroscopy axis in precision measurements on large Coulomb crystals. Finally, we compare trapping potential anharmonicity, which can induce nonlinear resonance heating by shifting normal mode frequencies onto resonance as a crystal grows. We apply a non-deforming crystal approximation for simple calculation of these anharmonicity-induced shifts, allowing a straightforward estimation of when crystal growth can lead to excitation of diff...

10. Antiproton-Nucleus Interaction and Coulomb Effect at High Energies

Institute of Scientific and Technical Information of China (English)

ZHOU Li-Juan; WU Qing; GU Yun-Ting; MA Wei-Xing; TAN Zhen-Qiang; HU Zhao-Hui

2005-01-01

The Coulomb effect in high energy antiproton-nucleus elastic and inelastic scattering from 12C and 16O is studied in the framework of Glauber multiple scattering theory for five kinetic energies ranged from 0.23 to 1.83 GeV.A microscopic shell-model nuclear wave functions, Woods-Saxon single-particle wave functions, and experimental pN amplitudes are used in the calculations. The results show that the Coulomb effect is of paramount importance for filling up the dips of differential cross sections. We claim that the present result for inelastic scattering of antiproton-12C is sufficiently reliable to be a guide for measurements in the very near future. We also believe that antiproton nucleus elastic and inelastic scattering may produce new information on both the nuclear structure and the antinucleon-nucleon interaction, in particular the p-neutron interaction.

11. Coulombic Fluids Bulk and Interfaces

CERN Document Server

Freyland, Werner

2011-01-01

Ionic liquids have attracted considerable interest in recent years. In this book the bulk and interfacial physico-chemical characteristics of various fluid systems dominated by Coulomb interactions are treated which includes molten salts, ionic liquids as well as metal-molten salt mixtures and expanded fluid metals. Of particular interest is the comparison of the different systems. Topics in the bulk phase concern the microscopic structure, the phase behaviour and critical phenomena, and the metal-nonmetal transition. Interfacial phenomena include wetting transitions, electrowetting, surface freezing, and the electrified ionic liquid/ electrode interface. With regard to the latter 2D and 3D electrochemical phase formation of metals and semi-conductors on the nanometer scale is described for a number of selected examples. The basic concepts and various experimental methods are introduced making the book suitable for both graduate students and researchers interested in Coulombic fluids.

12. Coulomb dissociation of N,2120

Science.gov (United States)

Röder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamaño, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkäll, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Datta Pramanik, Ushasi; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Gonzalez Diaz, D.; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hâkan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Sanchez del Rio Saez, Jose; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai; R3B Collaboration

2016-06-01

Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N,2120 are reported. Relativistic N,2120 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the 19N (n ,γ )20N and 20N (n ,γ ) 21N excitation functions and thermonuclear reaction rates have been determined. The 19 (n ,γ )20N rate is up to a factor of 5 higher at T <1 GK with respect to previous theoretical calculations, leading to a 10% decrease in the predicted fluorine abundance.

13. Coulomb interactions in Ga LMIS

Czech Academy of Sciences Publication Activity Database

2008-01-01

Roč. 108, č. 5 (2008), s. 445-454. ISSN 0304-3991 Grant ostatní: EC 5RP(XE) G5RD-CT-2000-00344 Institutional research plan: CEZ:AV0Z20650511 Source of funding: R - rámcový projekt EK Keywords : liquid-metal ion sources * Coulomb interactions * energy width * virtual source size Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.629, year: 2008

14. Strong-Field S-Matrix Theory With Coulomb-Volkov Final State in All Orders

CERN Document Server

Faisal, F H M

2016-01-01

Despite its long standing usefulness for the analysis of various processes in intense laser fields, it is well-known that the so-called strong-field KFR or SFA ansatz does not account for the final-state Coulomb interaction. Due to its importance for the ubiquitous ionisation process, numerous heuristic attempts have been made during the last several decades to account for the final state Coulomb interaction with in the SFA. Also to this end an ad hoc model with the so-called Coulomb-Volkov final state was introduced a long time ago. However, till now, no systematic strong-field S-matrix expansion using the Coulomb-Volkov final state could be found. Here we solve this long standing problem by determining the Coulomb-Volkov Hamiltonian, identifying the rest-interaction in the final state, and explicitly constructng the Coulomb-Volkov propagator (or Green's function). We employ them to derive the complete S-matrix series for the ionisation amplitude governed by the Coulomb-Volkov final state in all orders. The ...

15. Scalar-QED ℎ-corrections to the Coulomb potential

International Nuclear Information System (INIS)

The leading long-distance 1-loop quantum corrections to the Coulomb potential are derived for scalar QED and their gauge-independence is explicitly checked. The potential is obtained from the direct calculation of the 2-particle scattering amplitude, taking into account all relevant 1-loop diagrams. Our investigation should be regarded as first step towards the same programme for effective Quantum Gravity. In particular, with our calculation in the framework of scalar QED, we are able to demonstrate the incompleteness of some previous studies concerning the quantum Gravity counterpart. (author)

16. Differential cross section measurements of the π-p elastic scattering in the Coulomb interference region between 30 and 140 GeV

International Nuclear Information System (INIS)

The differential cross section of elastic π--p scattering in the Coulomb interference region from 30 GeV to 140 GeV has been measured at the CERN SPS using in conjunction an ionization chamber recoil spectrometer and a forward multiwire proportional chamber-magnet spectrometer. The phase of the π--p forward hadronic amplitude was found to go four negative value (at 30 GeV) to positive value (at 140 GeV), passing through zero at about 60 GeV. The logarithmic slope at small /t/ (/t/ approximately 0.03 (GeV/c)2) has also been measured and was found to be higher by about 3 (GeV/c)-2 than the values determined at higher /t/ (/t/ = 0.2 (GeV/c)2)

17. PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems

Science.gov (United States)

Neilson, David; Senatore, Gaetano

2009-05-01

This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas

18. Coulomb-dominated low-energy deuteron stripping

International Nuclear Information System (INIS)

Analysis of a three-body model shows that Coulomb polarization of the deuteron has very little influence on the branching ratio A(d,p)/A(d,n) for transfer reactions on target nucleus A at very low deuteron energies (the Oppenheimer-Phillips effect). We see that polarization effects in transfer reactions are not related to the long range of the Coulomb field, but are caused by the more intense fields near the target nucleus. However, even in that region the induced dipole moment is limited by the deuteron binding, and it is small for low Z targets. We see in addition that the transfer amplitudes tend to be insensitive to any polarization admixtures in the entrance channel. On the other hand, the branching ratio can be affected by the Coulomb barrier for the bound final-state wave function of the proton, especially for very weakly bound final states. Brief remarks about the relation of stripping theory to special properties of the d+d system are included

19. Amplitude mediated chimera states

OpenAIRE

Sethia, Gautam C.; Sen, Abhijit; Johnston, George L.

2013-01-01

We investigate the possibility of obtaining chimera state solutions of the non-local Complex Ginzburg-Landau Equation (NLCGLE) in the strong coupling limit when it is important to retain amplitude variations. Our numerical studies reveal the existence of a variety of amplitude mediated chimera states (including stationary and non-stationary two cluster chimera states), that display intermittent emergence and decay of amplitude dips in their phase incoherent regions. The existence regions of t...

20. Periods and Feynman amplitudes

CERN Document Server

Brown, Francis

2016-01-01

Feynman amplitudes in perturbation theory form the basis for most predictions in particle collider experiments. The mathematical quantities which occur as amplitudes include values of the Riemann zeta function and relate to fundamental objects in number theory and algebraic geometry. This talk reviews some of the recent developments in this field, and explains how new ideas from algebraic geometry have led to much progress in our understanding of amplitudes. In particular, the idea that certain transcendental numbers, such as $\\pi$, can be viewed as a representation of a group, provides a powerful framework to study amplitudes which reveals many hidden structures.

1. Proportional Symbol Mapping in R

OpenAIRE

Susumu Tanimura; Chusi Kuroiwa; Tsutomu Mizota

2006-01-01

Visualization of spatial data on a map aids not only in data exploration but also in communication to impart spatial conception or ideas to others. Although recent carto-graphic functions in R are rapidly becoming richer, proportional symbol mapping, which is one of the common mapping approaches, has not been packaged thus far. Based on the theories of proportional symbol mapping developed in cartography, the authors developed some functions for proportional symbol mapping using R, including ...

2. PREFACE: Strongly Coupled Coulomb Systems

Science.gov (United States)

Fortov, Vladimir E.; Golden, Kenneth I.; Norman, Genri E.

2006-04-01

This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS) which was held during the week of 20 24 June 2005 in Moscow, Russia. The Moscow conference was the tenth in a series of conferences. The previous conferences were organized as follows. 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (organized by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (organized by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, NY, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) After 1995 the name of the series was changed from Strongly Coupled Plasmas' to the present name in order to extend the topics of the conferences. The planned frequency for the future is once every three years. The purpose of these conferences is to provide an international forum for the presentation and discussion of research accomplishments and ideas relating to a variety of plasma liquid and condensed matter systems, dominated by strong Coulomb interactions between their constituents. Strongly coupled Coulomb systems encompass diverse many-body systems and physical conditions. Each meeting has seen an evolution of topics and emphasis as new discoveries and new methods appear. This year, sessions were organized for invited presentations and posters on dense plasmas and warm matter, astrophysics and dense hydrogen, non-neutral and ultracold plasmas, dusty plasmas, condensed matter 2D and layered charged-particle systems, Coulomb liquids, and statistical theory of SCCS. Within

3. Coulomb correction calculations of pp Bremsstrahlung

International Nuclear Information System (INIS)

The effects of the Coulomb interaction upon the photon cross section and analyzing power from pp Bremsstrahlung have been studied in detail. Off-shell properties of the Coulomb T matrices have been considered but the associated, Coulomb modified, hadronic T matrices are important elements in any analyses of low energy, forward proton scattering data. At the lowest energy considered (5 MeV), the full calculations gave cross sections that were half the size of those found without Coulomb effects or with a simple model approximation to them. With increasing energy, the cross sections varied to those characteristic of magnetic interaction dominance and the specific differences due to Coulomb effects diminished. 47 refs., 7 figs

4. Coulomb Potentials between Spherical and Deformed Nuclei

Institute of Scientific and Technical Information of China (English)

ZHANG Gao-Long; LE Xiao-Yun; LIU Zu-Hua

2008-01-01

@@ Coulomb potentials for spherical-deformed reaction partners are calculated in terms of the double folding model as well as the conventional formulas. Our results show that the Coulomb potentials calculated with different approaches have quite different behaviours in the internal region of the potential. Because fusion process is sensitive to the barrier height and the internal part of the potential, the fusion excitation function, especially the fusion barrier distribution, should provide a strict test of the interaction potentiaLs. Therefore, we calculate the fusion excitation function and barrier distribution for the 16O+154 Sm system with different versions of the Coulomb potentials, in comparison with the experimental results. It is found that the fusion excitation function and barrier distribution of 16 O+154 Sm are obviously different for the different versions of the Coulomb potentials.By means of this comparison, we may conclude that the double folding model with the accurate approximate form can provide rather reasonable Coulomb potentials.

5. Logarithmic torus amplitudes

Energy Technology Data Exchange (ETDEWEB)

Flohr, Michael [Physikalisches Institut, University of Bonn, Nussallee 12, D-53115 Bonn (Germany); Gaberdiel, Matthias R [Institut fuer Theoretische Physik, ETH Zuerich, ETH-Hoenggerberg, 8093 Zurich (Switzerland)

2006-02-24

For the example of the logarithmic triplet theory at c = -2, the chiral vacuum torus amplitudes are analysed. It is found that the space of these torus amplitudes is spanned by the characters of the irreducible representations, as well as a function that can be associated with the logarithmic extension of the vacuum representation. A few implications and generalizations of this result are discussed.

6. The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.

Science.gov (United States)

Francisco, E.; And Others

1988-01-01

Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

7. Amplitudes, acquisition and imaging

Energy Technology Data Exchange (ETDEWEB)

Bloor, Robert

1998-12-31

Accurate seismic amplitude information is important for the successful evaluation of many prospects and the importance of such amplitude information is increasing with the advent of time lapse seismic techniques. It is now widely accepted that the proper treatment of amplitudes requires seismic imaging in the form of either time or depth migration. A key factor in seismic imaging is the spatial sampling of the data and its relationship to the imaging algorithms. This presentation demonstrates that acquisition caused spatial sampling irregularity can affect the seismic imaging and perturb amplitudes. Equalization helps to balance the amplitudes, and the dealing strategy improves the imaging further when there are azimuth variations. Equalization and dealiasing can also help with the acquisition irregularities caused by shot and receiver dislocation or missing traces. 2 refs., 2 figs.

8. Proportioning of light weight concrete

DEFF Research Database (Denmark)

Palmus, Lars

1996-01-01

Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory......Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory...

9. Proportional Symbol Mapping in R

Directory of Open Access Journals (Sweden)

Susumu Tanimura

2006-01-01

Full Text Available Visualization of spatial data on a map aids not only in data exploration but also in communication to impart spatial conception or ideas to others. Although recent carto-graphic functions in R are rapidly becoming richer, proportional symbol mapping, which is one of the common mapping approaches, has not been packaged thus far. Based on the theories of proportional symbol mapping developed in cartography, the authors developed some functions for proportional symbol mapping using R, including mathematical and perceptual scaling. An example of these functions demonstrated the new expressive power and options available in R, particularly for the visualization of conceptual point data.

10. Coulomb continuum effects in molecular interference

International Nuclear Information System (INIS)

We study analytically the interference in photoionization of molecules by monochromatic and attosecond x-ray pulses. Using the hydrogen molecule ion as a test case, we obtain simple analytical factors describing the Coulomb continuum molecular interference. We show how chirped attosecond pulse with a frequency-dependent phase and broad bandwidth creates the continuous photoelectron spectra. Due to the long-range Coulomb forces, the plane wave interference patterns are strongly modified by two-centre Coulomb continuum even at large internuclear distances. (letter to the editor)

11. Multiwire proportional chamber with a dielectric film. Numerical study

International Nuclear Information System (INIS)

Electrostatical properties of multiwire proportional chambers with a dielectric film of low conductivity are considered. Distribution of the electric field in the chamber was obtained using numerical methods. This allowed investigating the influence of various parameters (chamber geometry, voltage at the electrodes) on the chamber working characteristics. Dependence of the chamber amplitude characteristics on the counting rate was also obtained

12. Coulomb Friction Driving Brownian Motors

International Nuclear Information System (INIS)

We review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation (linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a “collisional noise”, that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein—Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced. (general)

13. Scattering amplitudes in four- and six-dimensional gauge theories

International Nuclear Information System (INIS)

We study scattering amplitudes in quantum chromodynamics (QCD), N=4 super Yang-Mills (SYM) theory and the six-dimensional N=(1,1) SYM theory, focusing on the symmetries of and relations between the tree-level scattering amplitudes in these three gauge theories. We derive the tree level and one-loop color decomposition of an arbitrary QCD amplitude into primitive amplitudes. Furthermore, we derive identities spanning the null space among the primitive amplitudes. We prove that every color ordered tree amplitude of massless QCD can be obtained from gluon-gluino amplitudes of N=4 SYM theory. Furthermore, we derive analytical formulae for all gluon-gluino amplitudes relevant for QCD. We compare the numerical efficiency and accuracy of evaluating these closed analytic formulae for color ordered QCD tree amplitudes to a numerically efficient implementation of the Berends-Giele recursion. We derive the symmetries of massive tree amplitudes on the coulomb branch of N=4 SYM theory, which in turn can be obtained from N=(1,1) SYM theory by dimensional reduction. Furthermore, we investigate the tree amplitudes of N=(1, 1) SYM theory and explain how analytical formulae can be obtained from a numerical implementation of the supersymmetric BCFW recursion relation and investigate a potential uplift of the massless tree amplitudes of N=4 SYM theory. Finally we study an alternative to dimensional regularization of N=4 SYM theory. The infrared divergences are regulated by masses obtained from a Higgs mechanism. The corresponding string theory set-up suggests that the amplitudes have an exact dual conformal symmetry. We confirm this expectation and illustrate the calculational advantages of the massive regulator by explicit calculations.

14. Quarks in Coulomb gauge perturbation theory

CERN Document Server

Popovici, C; Reinhardt, H

2008-01-01

Coulomb gauge quantum chromodynamics within the first order functional formalism is considered. The quark contributions to the Dyson-Schwinger equations are derived and one-loop perturbative results for the two-point functions are presented.

15. Numerical path integration with Coulomb potential

OpenAIRE

Myrheim, Jan

2003-01-01

A simple and efficient method for quantum Monte Carlo simulation is presented, based on discretization of the action in the path integral, and a Gaussian averaging of the potential, which works well e.g. with the Coulomb potential.

16. Aspects of Confinement in Coulomb Gauge

CERN Document Server

Greensite, Jeff

2009-01-01

I present some new results regarding confinement as it appears in Coulomb gauge. It is found that: i) a recently proposed Yang-Mills vacuum wavefunctional in temporal gauge and 2+1 dimensions yields a Coulomb-gauge ghost propagator and linear Coulomb potential in good agreement with lattice Monte Carlo results; ii) adding a few constituent gluons to heavy quark-antiquark states brings the interaction energy much closer to that of the static quark potential, and suggests the beginnings of gluon-chain formation at roughly one fermi; iii) a perturbative approach to Faddeev-Popov eigenvalues indicates that the zero eigenvalue at the Gribov horizon may occur either at, or away from, p=0, depending on the gauge choice and spacetime dimension. This last result may be relevant to the qualitatively different infrared behavior of the ghost propagator in Coulomb and Landau gauges.

17. Coulomb Interaction Does Not Spread Instantaneously

CERN Document Server

Tzontchev, R I; Rivera-Juarez, J M

2000-01-01

The experiment is described which shows that Coulomb interaction spreads with a limit velocity and thus this kind of interaction cannot be considered as so called "instantaneous action at a distance".

18. Coulomb dissociation at nonrelativistic and relativistic energies

International Nuclear Information System (INIS)

The author studies the breakup of deuterons on nuclei in the framework of DWBA theories which are based on the spectator model. The discrepancies for heavy targets are explained by the mechanism of the Coulomb dissociation. (HSI)

19. Comments on Coulomb pairing in aromatic hydrocarbons

CERN Document Server

Huber, D L

2013-01-01

Recently reported anomalies in the double-photonionization spectra of aromatic molecules such as benzene, naphthalene, anthracene and coronene are attributed to Coulomb-pair resonances of pi electrons.

20. On the modelling of Coulomb friction

Science.gov (United States)

Cull, S. J.; Tucker, R. W.

1999-03-01

This paper analyses two different representations of Coulomb friction in the context of a dynamic simulation of the torsional vibrations of a driven drill-string. A simple model is used to compare the relative merits of a piecewise analytic approach using a discontinuous friction profile to a numerical integration using a smooth nonlinear representation of the Coulomb friction. In both cases the effects of viscous damping on the excitation of torsional relaxation oscillations are exhibited.

1. Cavity QED experiments with ion Coulomb crystals

DEFF Research Database (Denmark)

Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan; Albert, Magnus; Drewsen, Michael

Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained.......Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....

2. Coulomb interactions in particle beams

International Nuclear Information System (INIS)

This thesis presents a theoretical description of the Coulomb interaction between identical charged particles (electrons or ions) in focussed beam. The charge-density effects as well as the various statistical interaction effects, known as the Boersch effect and the 'trajectory displacement effect', are treated. An introductory literature survey is presented from which the large differences in theoretical approach appear. Subsequently the methods are investigated which are used in studies of comparable problems in plasma physics and stellar dynamics. These turn out to be applicable to particle beams only for certain extreme conditions. The approach finally chosen in this study is twofold. On the one hand use is made of a semi-analytical model in which the statistical and dynamical aspects of the N-particle problem are reduced to two-particle problem. This model results in a number of explicit equations in the experimental parameters, with ties of the beam can be determined directly. On the other hand use has been made of a purely numerical Monte Carlo model in which the kinematical equations of an ensemble interacting particles with 'at random' chosen starting conditions are solved exactly. This model does not lead to general expressions, but yields a specific numerical prediction for each simulated experimental situation. The results of both models appear to agree well mutually. This yields a consistent theory which complements the existing knowledge of particle optics and which allow the description of systems in which the interaction between particles can not be neglected. The predictions of this theory are qualitatively and quantitatively compared with those from some other models, recently reported in literature. (author). 256 refs.; 114 figs.; 1180 schemes; 5 tabs

3. 16O Coulomb decomposition project '93

International Nuclear Information System (INIS)

The adaptability of magnetic analyzers in Japan to this research project was compared and investigated, and the Coulomb decomposition process and the experimental conditions for 16O were examined. By the measurement of the delayed-α spectrum in 16N decay, a new restriction was set to the E1 reaction rate of 12C(α, γ)16O reaction. Hereafter, the research on the E2 reaction rate is urgently needed. There is large expectation for the Coulomb decomposition reaction of 16O as the probe especially sensitive to the E2 reaction rate of the important reaction for celestial body physics. At the meeting held on July 30, the RIKEN SMART spectrometer (F2) was judged as optimal, and its merits are explained. Also a demerit is pointed out. The ion optic parameters of the SMART F2 are shown. In the meeting held on December 17, investigation was carried out on α-12C coincidence count rate and projectile fragmentation background, Coulomb decomposition process and focal plane detector. The reaction cross section of Coulomb E2 excitation was evaluated by Monte Carlo method. As to the possibility of applying Coulomb decomposition process under the circumstance that nuclear force and Coulomb force compete, the new direction was indicated. The experimental plan is shown. (K.I.)

4. Yang-Mills theory in Coulomb gauge

International Nuclear Information System (INIS)

In this thesis we study the Yang-Mills vacuum structure by using the functional Schroedinger picture in Coulomb gauge. In particular we discuss the scenario of colour confinement, which was originally formulated by Gribov. After a short introduction, we recall some basic aspects of Yang-Mills theories, its canonical quantization in the Weyl gauge and the functional Schroedinger picture. We then consider the minimal Coulomb gauge and the Gribov problem of the gauge theory. The gauge fixing of the Coulomb gauge is done by using the Faddeev-Popov method, which enables the resolution of the Gauss law - the constraint on physical states. In the third chapter, we variationally solve the stationary Yang-Mills Schroedinger equation in Coulomb gauge for the vacuum state. Therefor we use a vacuum wave functional, which is strongly peaked at the Gribov horizon. The vacuum energy functional is calculated and minimized resulting in a set of coupled Schwinger-Dyson equations for the gluon energy, the ghost and Coulomb form factors and the curvature in gauge orbit space. Using the angular approximation these integral equations have been solved analytically in both the infrared and the ultraviolet regime. The asymptotic analytic solutions in the infrared and ultraviolet regime are reasonably well reproduced by the full numerical solutions of the coupled Schwinger-Dyson equations. In the fourth chapter, we investigate the dependence of the Yang-Mills wave functional in Coulomb gauge on the Faddeev-Popov determinant. (orig.)

5. Asymptotic regimes for diffractive scatterings at ultrahigh energies and coulomb interaction

CERN Document Server

Anisovich, V V; Nyiri, J

2016-01-01

Comparative analysis of the interplay of hadron and Coulomb interactions in $pp^\\pm$ scattering amplitudes is performed for two extreme cases: for the asymptotic interaction of hadrons in black disk and resonant disk modes. The interactions are discussed in terms of the $K$-matrix function technique, the interference effects are estimated in the energy interval $\\sqrt{s}=1-10^6$ TeV. In both cases the real part of the hadronic amplitude is concentrated on the boundary of the disks in the impact parameter space that causes a growth of interference effects with the energy increase. For the $pp$ scattering at $\\sqrt{s}\\sim 10$ TeV an interplay of the hadron and Coulomb interactions in the resonant disk modes is realized in a specific shoulder in $d\\sigma_{el}/d{\\bf q}^2$ at ${\\bf q}^2\\sim 0.0025-0.0075$ GeV$^2$.

6. Development of multiwire proportional chambers

CERN Multimedia

Charpak, G

1969-01-01

It has happened quite often in the history of science that theoreticians, confronted with some major difficulty, have successfully gone back thirty years to look at ideas that had then been thrown overboard. But it is rare that experimentalists go back thirty years to look again at equipment which had become out-dated. This is what Charpak and his colleagues did to emerge with the 'multiwire proportional chamber' which has several new features making it a very useful addition to the armoury of particle detectors. In the 1930s, ion-chambers, Geiger- Muller counters and proportional counters, were vital pieces of equipment in nuclear physics research. Other types of detectors have since largely replaced them but now the proportional counter, in new array, is making a comeback.

7. Bayesian inference on proportional elections.

Science.gov (United States)

Brunello, Gabriel Hideki Vatanabe; Nakano, Eduardo Yoshio

2015-01-01

Polls for majoritarian voting systems usually show estimates of the percentage of votes for each candidate. However, proportional vote systems do not necessarily guarantee the candidate with the most percentage of votes will be elected. Thus, traditional methods used in majoritarian elections cannot be applied on proportional elections. In this context, the purpose of this paper was to perform a Bayesian inference on proportional elections considering the Brazilian system of seats distribution. More specifically, a methodology to answer the probability that a given party will have representation on the chamber of deputies was developed. Inferences were made on a Bayesian scenario using the Monte Carlo simulation technique, and the developed methodology was applied on data from the Brazilian elections for Members of the Legislative Assembly and Federal Chamber of Deputies in 2010. A performance rate was also presented to evaluate the efficiency of the methodology. Calculations and simulations were carried out using the free R statistical software. PMID:25786259

8. Protostring Scattering Amplitudes

CERN Document Server

Thorn, Charles B

2016-01-01

We calculate some tree level scattering amplitudes for a generalization of the protostring, which is a novel string model implied by the simplest string bit models. These bit models produce a lightcone worldsheet which supports $s$ integer moded Grassmann fields. In the generalization we supplement this Grassmann worldsheet system with $d=24-s$ transverse coordinate worldsheet fields. The protostring corresponds to $s=24$ and the bosonic string to $s=0$. The interaction vertex is a simple overlap with no operator insertions at the break/join point. Assuming that $s$ is even we calculate the multi-string scattering amplitudes by bosonizing the Grassmann fields, each pair equivalent to one compactified bosonic field, and applying Mandelstam's interacting string formalism to a system of $s/2$ compactified and $d$ uncompactified bosonic worldsheet fields. We obtain all amplitudes for open strings with no oscillator excitations and for closed strings with no oscillator excitations and zero winding number. We then ...

9. Primakoff production of $\\pi^0$, $\\eta$ and $\\eta'$ in the Coulomb field of a nucleus

OpenAIRE

2011-01-01

Photoproduction of neutral pseudoscalar mesons $\\pi^0,\\eta(547)$ and $\\eta'(958)$ in the Coulomb field of an atomic nucleus is studied using a model which describes the Primakoff and nuclear parts of the production amplitude. At high energies the nuclear background is dominated by the exchange of $C$-parity odd Regge trajectories. In the coherent production the isospin filtering makes the $\\omega(782)$ a dominant trajectory. The calculations are in agreement with $\\pi^0$ data from JLAB provid...

10. Universal Correlations of Coulomb Blockade Conductance Peaks and the Rotation Scaling in Quantum Dots

OpenAIRE

Alhassid, Y.; Attias, H.

1996-01-01

We show that the parametric correlations of the conductance peak amplitudes of a chaotic or weakly disordered quantum dot in the Coulomb blockade regime become universal upon an appropriate scaling of the parameter. We compute the universal forms of this correlator for both cases of conserved and broken time reversal symmetry. For a symmetric dot the correlator is independent of the details in each lead such as the number of channels and their correlation. We derive a new scaling, which we ca...

11. Electrostatics of Coulomb gas, lattice paths and discrete polynuclear growth

International Nuclear Information System (INIS)

We study the partition function of a two-dimensional Coulomb gas on a circle, in the presence of external pointlike charges, in a double scaling limit where both the external charges and the number of gas particles are large. Our original motivation comes from studying amplitudes for multi-string emission from a decaying D-brane in the high-energy limit. We analyze the scaling limit of the partition function and calculate explicit results. We also consider applications to random matrix theory. The partition functions can be related to random scattering or to weights of lattice paths in certain growth models. In particular, we consider the discrete polynuclear growth model and use our results to compute the cumulative probability density for the height of long level-1 paths. We also obtain an estimate for an almost certain maximum height.

12. Observation of multistep Coulomb excitation during ion-atom collisions

International Nuclear Information System (INIS)

Well below the Coulomb barrier energies two colliding nuclei may share the energy via electromagnetic interactions and it can lead to excite the nuclear states of one or both the participating nuclei. This long range Coulombic interaction leading to nuclear excitation is called Coulomb excitation. In the present work, we have studied heavy ion induced Coulomb excitation process in 12C nuclei at the sub-Coulomb barrier energies using x-ray spectroscopy technique in combination with the nuclear techniques.

13. Social Justice and Proportional Reasoning

Science.gov (United States)

Simic-Muller, Ksenija

2015-01-01

Ratio and proportional reasoning tasks abound that have connections to real-world situations. Examples in this article demonstrate how textbook tasks can easily be transformed into authentic real-world problems that shed light on issues of equity and fairness, such as population growth and crime rates. A few ideas are presented on how teachers can…

14. Body proportions in Turner's syndrome.

OpenAIRE

Hughes, P C; Ribeiro, J; Hughes, I A

1986-01-01

Body proportion was studied in Turner's syndrome by measurement of standing an sitting heights in relation to chronological and bone age. The mean standard deviation score for standing height was -3.8. Disproportionate growth of the legs was not a major determinant of short stature, either before or after oestrogen replacement.

15. Constant Proportion Debt Obligations (CPDOs)

DEFF Research Database (Denmark)

Cont, Rama; Jessen, Cathrine

2012-01-01

Constant Proportion Debt Obligations (CPDOs) are structured credit derivatives that generate high coupon payments by dynamically leveraging a position in an underlying portfolio of investment-grade index default swaps. CPDO coupons and principal notes received high initial credit ratings from the...

16. Scaling of saturation amplitudes in baroclinic instability

International Nuclear Information System (INIS)

By using finite-amplitude conservation laws for pseudomomentum and pseudoenergy, rigorous upper bounds have been derived on the saturation amplitudes in baroclinic instability for layered and continuously-stratified quasi-geostrophic models. Bounds have been obtained for both the eddy energy and the eddy potential enstrophy. The bounds apply to conservative (inviscid, unforced) flow, as well as to forced-dissipative flow when the dissipation is proportional to the potential vorticity. This approach provides an efficient way of extracting an analytical estimate of the dynamical scalings of the saturation amplitudes in terms of crucial non-dimensional parameters. A possible use is in constructing eddy parameterization schemes for zonally-averaged climate models. The scaling dependences are summarized, and compared with those derived from weakly-nonlinear theory and from baroclinic-adjustment estimates

17. Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals

Science.gov (United States)

Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

2007-04-01

The authors propose a new linear-scaling method for the fast evaluation of Coulomb integrals with Gaussian basis functions called the Gaussian and finite-element Coulomb (GFC) method. In this method, the Coulomb potential is expanded in a basis of mixed Gaussian and finite-element auxiliary functions that express the core and smooth Coulomb potentials, respectively. Coulomb integrals can be evaluated by three-center one-electron overlap integrals among two Gaussian basis functions and one mixed auxiliary function. Thus, the computational cost and scaling for large molecules are drastically reduced. Several applications to molecular systems show that the GFC method is more efficient than the analytical integration approach that requires four-center two-electron repulsion integrals. The GFC method realizes a near linear scaling for both one-dimensional alanine α-helix chains and three-dimensional diamond pieces.

18. Disease proportions attributable to environment

Directory of Open Access Journals (Sweden)

Vineis Paolo

2007-11-01

Full Text Available Abstract Population disease proportions attributable to various causal agents are popular as they present a simplified view of the contribution of each agent to the disease load. However they are only summary figures that may be easily misinterpreted or over-interpreted even when the causal link between an exposure and an effect is well established. This commentary discusses several issues surrounding the estimation of attributable proportions, particularly with reference to environmental causes of cancers, and critically examines two recently published papers. These issues encompass potential biases as well as the very definition of environment and of environmental agent. The latter aspect is not just a semantic question but carries implications for the focus of preventive actions, whether centred on the material and social environment or on single individuals.

19. Proportional counter as neutron detector

Science.gov (United States)

Braby, L. A.; Badhwar, G. D.

2001-01-01

A technique to separate out the dose, and lineal energy spectra of neutrons and charged particles is described. It is based on using two proportional counters, one with a wall, and the other with similar characteristics but wall made from a non-hydrogen containing material. Results of a calibration in a neutron field are also shown. c2001 Elsevier Science Ltd. All rights reserved.

20. Metacarpal proportions in Australopithecus africanus.

Science.gov (United States)

Green, David J; Gordon, Adam D

2008-05-01

Recent work has shown that, despite being craniodentally more derived, Australopithecus africanus had more apelike limb-size proportions than A. afarensis. Here, we test whether the A. africanus hand, as judged by metacarpal shaft and articular proportions, was similarly apelike. More specifically, did A. africanus have a short and narrow first metacarpal (MC1) relative to the other metacarpals? Proportions of both MC breadth and length were considered: the geometric mean (GM) of articular and midshaft measurements of MC1 breadth was compared to those of MC2-4, and MC1 length was compared to MC3 length individually and also to the GM of MC2 and 3 lengths. To compare the extant hominoid sample with an incomplete A. africanus fossil record (11 attributed metacarpals), a resampling procedure imposed sampling constraints on the comparative groups that produced composite intrahand ratios. Resampled ratios in the extant sample are not significantly different from actual ratios based on associated elements, demonstrating the methodological appropriateness of this technique. Australopithecus africanus metacarpals do not differ significantly from the great apes in the comparison of breadth ratios but are significantly greater than chimpanzees and orangutans in both measures of relative length. Conversely, A. africanus has a significantly smaller breadth ratio than modern humans, but does not significantly differ from this group in either measure of relative length. We conclude that the first metacarpals of A. africanus are more apelike in relative breadth while also being more humanlike in relative length, a finding consistent with previous work on A. afarensis hand proportions. This configuration would have likely promoted a high degree of manipulative dexterity, but the relatively slender, apelike first metacarpal suggests that A. africanus did not place the same mechanical demands on the thumb as more recent, stone-tool-producing hominins. PMID:18191176

1. Coulomb-potential-dependent decohesion of Magneli phases

International Nuclear Information System (INIS)

Transition metal oxide Magneli phases are traditionally described as crystallographic shear structures. Some of these phases feature a layered crystal structure based on deformed metal-oxygen octahedra. Here, we describe the correlation between structure, decohesion energies and elastic properties of WO3, ReO3, MoO2, VO2, V2O5 and TiO2 using ab initio calculations. Decohesion energies and elastic constants C44 are inversely proportional to the original distance between the cleaved layers and correspond to the screened Coulomb potential. This can be understood based on the electronic structure. The bond strength decreases rapidly as the distance is increased, resulting in weak coupling between the layers, which in turn causes the formation of easily plastically deformable structures. (fast track communication)

2. Light Meson Distribution Amplitudes

CERN Document Server

Arthur, R; Brommel, D; Donnellan, M A; Flynn, J M; Juttner, A; de Lima, H Pedroso; Rae, T D; Sachrajda, C T; Samways, B

2010-01-01

We calculated the first two moments of the light-cone distribution amplitudes for the pseudoscalar mesons ($\\pi$ and $K$) and the longitudinally polarised vector mesons ($\\rho$, $K^*$ and $\\phi$) as part of the UKQCD and RBC collaborations' $N_f=2+1$ domain-wall fermion phenomenology programme. These quantities were obtained with a good precision and, in particular, the expected effects of $SU(3)$-flavour symmetry breaking were observed. Operators were renormalised non-perturbatively and extrapolations to the physical point were made, guided by leading order chiral perturbation theory. The main results presented are for two volumes, $16^3\\times 32$ and $24^3\\times 64$, with a common lattice spacing. Preliminary results for a lattice with a finer lattice spacing, $32^3\\times64$, are discussed and a first look is taken at the use of twisted boundary conditions to extract distribution amplitudes.

3. Periods and Superstring Amplitudes

CERN Document Server

Stieberger, S

2016-01-01

Scattering amplitudes which describe the interaction of physical states play an important role in determining physical observables. In string theory the physical states are given by vibrations of open and closed strings and their interactions are described (at the leading order in perturbation theory) by a world-sheet given by the topology of a disk or sphere, respectively. Formally, for scattering of N strings this leads to N-3-dimensional iterated real integrals along the compactified real axis or N-3-dimensional complex sphere integrals, respectively. As a consequence the physical observables are described by periods on M_{0,N} - the moduli space of Riemann spheres of N ordered marked points. The mathematical structure of these string amplitudes share many recent advances in arithmetic algebraic geometry and number theory like multiple zeta values, single-valued multiple zeta values, Drinfeld, Deligne associators, Hopf algebra and Lie algebra structures related to Grothendiecks Galois theory. We review the...

4. HIGH AMPLITUDE PROPAGATED CONTRACTIONS

OpenAIRE

2012-01-01

While most colonic motor activity is segmental and non-propulsive, colonic high amplitude propagated contractions (HAPC) can transfer colonic contents over long distances and often precede defecation. HAPC occur spontaneously, in response to pharmacological agents or colonic distention. In this issue of Neurogastroenterology and Motility, Rodriguez and colleagues report that anal relaxation during spontaneous and bisacodyl-induced HAPC exceeds anal relaxation during rectal distention in const...

5. Orbital Ordering Induced by Direct Coulomb Repulsion

Institute of Scientific and Technical Information of China (English)

HUANG Yuan-Yie; ZHANG Yu-Heng

2011-01-01

We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering (OO) based on the direct coulomb repulsion in this article. The results show that the orbital-orbital interaction (OO-I) between the adjacent ions in 180-degree configuration is dominated by the superexchange energy accompanied by a weak orbital-spin coupling, and the OO-I in 90-degree configuration is monitored by the oxygen on-site coulomb repulsion. The ferro-OO is the stable ground state for the one-dimensional chain in the case of the 90-degree configuration.

6. Coulomb interaction in few-nucleon systems

International Nuclear Information System (INIS)

Mathematical aspects of scattering quantum theory are considered. A brief review of methods proposed for solution of the following problems is presented: a) description of properties of resolvant nucleus for the operator of energy of three charged particles system, 2) definition of total system of Coulomb wave functions, 3) definition of unitary Coulomb scattering operator, 4) study of singularity of its nucleus, 5) establishing of relation between stationary and non stationary formulations of the scattering theory. The solution of these problems is obtained by means of a new form of Faddeev integral equations. The equations are formulated and studied in configuration space

7. Testing of Coulomb-Volkov functions

International Nuclear Information System (INIS)

A time-dependent generalization of the Siegert theorem is applied to test the accuracy of the Coulomb-Volkov functions (CVFs) widely used for the description of electron motion in a laser field combined with the Coulomb field of the atomic core. Free-free transitions in the case of arbitrary elliptic polarization of the electromagnetic field are investigated. It is shown that the ratio between the strength of the light wave electric field and its frequency (in atomic units) has crucial importance for estimation of the CVF accuracy. (author)

8. Efficient evaluation of the Coulomb force in the Gaussian and finite-element Coulomb method

Science.gov (United States)

Kurashige, Yuki; Nakajima, Takahito; Sato, Takeshi; Hirao, Kimihiko

2010-06-01

We propose an efficient method for evaluating the Coulomb force in the Gaussian and finite-element Coulomb (GFC) method, which is a linear-scaling approach for evaluating the Coulomb matrix and energy in large molecular systems. The efficient evaluation of the analytical gradient in the GFC is not straightforward as well as the evaluation of the energy because the SCF procedure with the Coulomb matrix does not give a variational solution for the Coulomb energy. Thus, an efficient approximate method is alternatively proposed, in which the Coulomb potential is expanded in the Gaussian and finite-element auxiliary functions as done in the GFC. To minimize the error in the gradient not just in the energy, the derived functions of the original auxiliary functions of the GFC are used additionally for the evaluation of the Coulomb gradient. In fact, the use of the derived functions significantly improves the accuracy of this approach. Although these additional auxiliary functions enlarge the size of the discretized Poisson equation and thereby increase the computational cost, it maintains the near linear scaling as the GFC and does not affects the overall efficiency of the GFC approach.

9. Amplitude scaling of asymmetry-induced transport

International Nuclear Information System (INIS)

Our initial experiments on asymmetry-induced transport in non-neutral plasmas found the radial particle flux at small radii to be proportional to φa2, where φa is the applied asymmetry amplitude. Other researchers, however, using the global expansion rate as a measure of the transport, have observed a φa1 scaling when the rigidity (the ratio of the axial bounce frequency to the azimuthal rotation frequency) is in the range one to ten. In an effort to resolve this discrepancy, we have extended our measurements to different radii and asymmetry frequencies. Although the results to date are generally in agreement with those previously reported (φa2 scaling at low asymmetry amplitudes falling off to a weaker scaling at higher amplitudes), we have observed some cases where the low amplitude scaling is closer to φa1. Both the φa2 and φa1 cases, however, have rigidities less than ten. Instead, we find that the φa1 cases are characterized by an induced flux that is comparable in magnitude but opposite in sign to the background flux. This suggests that the mixing of applied and background asymmetries plays an important role in determining the amplitude scaling of this transport

10. Statistical inference on mixing proportion

Institute of Scientific and Technical Information of China (English)

2008-01-01

In this paper, the interval estimation and hypothesis testing of the mixing proportion in mixture distributions are considered. A statistical inferential method is proposed which is inspired by the generalized p-values and generalized pivotal quantity. In some situations, the true levels of the tests given in the paper are equal to nominal levels, and the true coverage of the interval estimation or confidence bounds is also equal to nominal one. In other situations, under mild conditions, the tests are consistent and the coverage of the interval estimations or the confidence bounds is asymptotically equal to nominal coverage. Meanwhile, some simulations are performed which show that our method is satisfactory.

11. Module of System Galactica with Coulomb's Interaction

OpenAIRE

Smulsky, Joseph J

2014-01-01

The system Galactica of free access is supplemented module for the Coulomb interaction. It is based on a high-precision method for solving differential equations of motion of N charged particles. The paper presents all the theoretical and practical issues required to use this module of system Galactica so that even the beginning researcher could study the motion of particles, atoms and molecules.

12. On Confinement in Coulomb Gauge QCD

International Nuclear Information System (INIS)

Full text: We study the quark propagator in Coulomb gauge QCD and employ the corresponding results to calculate meson properties. We demonstrate a mechanism how color non-singlets as e.g. diquarks in the color anti-triplet state are confined. (author)

13. Bound - states for truncated Coulomb potentials

OpenAIRE

Odeh, Maen; Mustafa, Omar

2000-01-01

The pseudoperturbative shifted - $l$ expansion technique PSLET is generalized for states with arbitrary number of nodal zeros. Bound- states energy eigenvalues for two truncated coulombic potentials are calculated using PSLET. In contrast with shifted large-N expansion technique, PSLET results compare excellently with those from direct numerical integration.

14. Coulomb drag in coherent mesoscopic systems

DEFF Research Database (Denmark)

Mortensen, Niels Asger; Flensberg, Karsten; Jauho, Antti-Pekka

2001-01-01

We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means, such as the...

15. BRST invariance in Coulomb gauge QCD

CERN Document Server

Andrasi, A

2015-01-01

In the Coulomb gauge, the Hamiltonian of QCD contains terms of order h^2, identified by Christ and Lee, which are non-local but instantaneous. The question is addressed how these terms fit in with BRST invariance. Our discussion is confined to the simplest, O(g^4), example.

16. BRST invariance in Coulomb gauge QCD

Science.gov (United States)

Andraši, A.; Taylor, J. C.

2015-12-01

In the Coulomb gauge, the Hamiltonian of QCD contains terms of order ħ2, identified by Christ and Lee, which are non-local but instantaneous. The question is addressed how do these terms fit in with BRST invariance. Our discussion is confined to the simplest, O(g4) , example.

17. Dynamical features of Coulomb-fission

International Nuclear Information System (INIS)

Fission following quasielastic scattering was investigated in the reactions 208Pb -> 238U below the Coulomb Barrier and 7.5 MeV/u 238U -> 238U at scattering angles forward of the grazing angle (870). A kinematically complete analysis of 3-body coincidences was carried out measuring position and time-of-flight of the scattered projectile-like particle and 2 fission fragments in large parallel plate detectors. In the reaction 208Pb -> 238U, measured at backward angles, the slope of the differential cross section at 5.4 MeV/u is in qualitative agreement with the theoretical expectation for Coulomb-fission. The angular distribution of the fission fragments, measured with respect to the semisector axis (apex line towards the projectile), is close to 1/sinTHETA and does not show any of the significant structures predicted by several theories. The anisotropy is smaller in all other coordinate systems investigated. The fission probability in the reaction 238U -> 238U, measured down to 5x10-4 at THETAsub(cm)=540 (corresponding to 75% Esub(cb) at the distance of closest approach) as well as the low excitation energy 0 as expected for Coulomb-fission. The absence of a detectable final state Coulomb interaction yields a lower limit of 1-2x10-20s for the lifetime of the fissioning nucleus. (orig./HSI)

18. Frictional Coulomb drag in strong magnetic fields

DEFF Research Database (Denmark)

Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang;

1997-01-01

A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21) is...

19. Coulomb functions with complex angular momenta

International Nuclear Information System (INIS)

The subroutine CCOULM calculates regular and irregular Coulomb functions and their derivatives associated with complex angular momenta. This program may thus be used, for example, in locating Regge poles that appear in atomic and nuclear scattering problems. The calculation utilized the asymptotic expansion method of Froeberg. (Auth.)

20. Coulomb drag in coherent mesoscopic systems

DEFF Research Database (Denmark)

Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka

2001-01-01

random matrix theory, or by numerical simulations. We show that Coulomb drag is sensitive to localized states. which usual transport measurements do not probe. For chaotic 2D systems we find a vanishing average drag, with a nonzero variance. Disordered 1D wires show a finite drag, with a large variance...

1. Quantum Amplitude Amplification and Estimation

CERN Document Server

Brassard, G; Mosca, M; Tapp, A; Brassard, Gilles; Hoyer, Peter; Mosca, Michele; Tapp, Alain

2000-01-01

Consider a Boolean function $\\chi: X \\to \\{0,1\\}$ that partitions set $X$ between its good and bad elements, where $x$ is good if $\\chi(x)=1$ and bad otherwise. Consider also a quantum algorithm $\\mathcal A$ such that $A \\ket{0} = \\sum_{x\\in X} \\alpha_x \\ket{x}$ is a quantum superposition of the elements of $X$, and let $a$ denote the probability that a good element is produced if $A \\ket{0}$ is measured. If we repeat the process of running $A$, measuring the output, and using $\\chi$ to check the validity of the result, we shall expect to repeat $1/a$ times on the average before a solution is found. *Amplitude amplification* is a process that allows to find a good $x$ after an expected number of applications of $A$ and its inverse which is proportional to $1/\\sqrt{a}$, assuming algorithm $A$ makes no measurements. This is a generalization of Grover's searching algorithm in which $A$ was restricted to producing an equal superposition of all members of $X$ and we had a promise that a single $x$ existed such tha...

2. Relativistic study of the energy-dependent Coulomb potential including Coulomb-like tensor interaction

CERN Document Server

Hamzavi, Majid

2012-01-01

The exact Dirac equation for the energy-dependent Coulomb (EDC) potential including a Coulomb-like tensor (CLT) potential has been studied in the presence of spin and pseudospin (p-spin) symmetries with arbitrary spin-orbit quantum number The energy eigenvalues and corresponding eigenfunctions are obtained in the framework of asymptotic iteration method (AIM). Some numerical results are obtained in the presence and absence of EDC and CLT potentials.

3. Sensor Craft Control Using Drone Craft with Coulomb Propulsion System

OpenAIRE

Joe, Hyunsik

2005-01-01

The Coulomb propulsion system has no exhaust plume impingement problem with neighboring spacecraft and does not contaminate their sensors because it requires essentially no propellant. It is suitable to close formation control on the order of dozens of meters. The Coulomb forces are internal forces of the formation and they influence all charged spacecraft at the same time. Highly nonlinear and strongly coupled equations of motion of Coulomb formation makes creating a Coulomb control method a...

4. Spin diffusion in doped semiconductors: the role of Coulomb interactions

OpenAIRE

D'Amico, Irene; Vignale, Giovanni

2000-01-01

We examine the effect of the Coulomb interaction on the mobility and diffusion of spin packets in doped semiconductors. We find that the diffusion constant is reduced, relative to its non-interacting value, by the combined effect of Coulomb-enhanced spin susceptibility and spin Coulomb drag. In ferromagnetic semiconductors, the spin diffusion constant vanishes at the ferromagnetic transition temperature.

5. Excitation and ionization of hydrogen and helium atoms by femtosecond laser pulses: theoretical approach by Coulomb-Volkov states

International Nuclear Information System (INIS)

We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when ℎω > Ip: it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with ℎω p: new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)

6. Voltage Fluctuation to Current Converter with Coulomb-Coupled Quantum Dots

Science.gov (United States)

Hartmann, F.; Pfeffer, P.; Höfling, S.; Kamp, M.; Worschech, L.

2015-04-01

We study the rectification of voltage fluctuations in a system consisting of two Coulomb-coupled quantum dots. The first quantum dot is connected to a reservoir where voltage fluctuations are supplied and the second one is attached to two separate leads via asymmetric and energy-dependent transport barriers. We observe a rectified output current through the second quantum dot depending quadratically on the noise amplitude supplied to the other Coulomb-coupled quantum dot. The current magnitude and direction can be switched by external gates, and maximum output currents are found in the nA region. The rectification delivers output powers in the pW region. Future devices derived from our sample may be applied for energy harvesting on the nanoscale beneficial for autonomous and energy-efficient electronic applications.

7. Closed string amplitudes as single-valued open string amplitudes

International Nuclear Information System (INIS)

We show that the single trace heterotic N-point tree-level gauge amplitude ANHET can be obtained from the corresponding type I amplitude ANI by the single-valued (sv) projection: ANHET=sv(ANI). This projection maps multiple zeta values to single-valued multiple zeta values. The latter represent a subclass of multiple zeta values originating from single-valued multiple polylogarithms at unity. Similar relations between open and closed string amplitudes or amplitudes of different string vacua can be established. As a consequence the α′-expansion of a closed string amplitude is dictated by that of the corresponding open string amplitude. The combination of single-valued projections, Kawai–Lewellen–Tye relations and Mellin correspondence reveal a unity of all tree-level open and closed superstring amplitudes together with the maximally supersymmetric Yang–Mills and supergravity theories

8. Challenging the principle of proportionality.

Science.gov (United States)

2016-04-01

The first objective of this article is to examine one aspect of the principle of proportionality (PP) as advanced by Alan Gewirth in his 1978 bookReason and Morality Gewirth claims that being capable of exercising agency to some minimal degree is a property that justifies having at least prima facie rights not to get killed. However, according to the PP, before the being possesses the capacity for exercising agency to that minimal degree, the extent of her rights depends on to what extent she approaches possession of agential capacities. One interpretation of PP holds that variations in degree of possession of the physical constitution necessary to exercise agency are morally relevant. The other interpretation holds that only variations in degree of actual mental capacity are morally relevant. The first of these interpretations is vastly more problematic than the other. The second objective is to argue that according to the most plausible interpretation of the PP, the fetus' level of development before at least the 20th week of pregnancy does not affect the fetus' moral rights status. I then suggest that my argument is not restricted to such fetuses, although extending my argument to more developed fetuses requires caution. PMID:26839114

9. Drift and proportional tracking chambers

International Nuclear Information System (INIS)

Many techniques have been exploited in constructing tracking chambers, particle detectors which measure the trajectories and momenta of charged particles. The particular features of high-energy interactions - charged particle multiplicities, angular correlations and complex vertex topologies, to name a few - and the experimental environment of the accelerator - event rates, background rates, and so on - accent the importance of certain detector characteristics. In high energy e+e-, anti pp and pp interactions the final states are dominated by closely collimated jets of high multiplicity, requiring good track-pair resolution in the tracking chamber. High energy particles deflect very little in limited magnetic field volumes, necessitating good spatial resolution for accurate momentum measurements. The colliding beam technique generally requires a device easily adapted to full solid-angle coverage, and the high event rates expected in some of these machines put a premium on good time resolution. Finally, the production and subsequent decays of the tau, charmed and beautiful mesons will provide multiple vertex topologies. To reconstruct these vertices reliably will require considerable improvements in spatial resolution and track-pair resolution. This lecture considers the proportional counter and its descendant, the drift chamber, as tracking chambers. Its goal is to review the physics of this device in order to understand its performance limitations and promises

10. Manifestation of nuclear cluster structure in Coulomb sums

CERN Document Server

Buki, A Yu

2016-01-01

Experimental Coulomb sum values of 6^Li and 7^Li nuclei have been obtained, extending the earlier reported momentum transfer range of Coulomb sums for these nuclei up to q = 0.750 ... 1.625 fm^-1. The dependence of the Coulomb sums on the momentum transfers of 6^Li and 7^Li is shown to differ substantially from similar dependences for all the other nuclei investigated. Relationship between the nuclear cluster structure and Coulomb sums has been considered. The momentum transfer value, above which the Coulomb sum becomes constant, is found to be related to the cluster isolation parameter x, which characterizes the degree of nuclear clusterization.

11. Coulomb interaction in Eliashberg theory of superconductivity

Energy Technology Data Exchange (ETDEWEB)

Davydov, Arkady; Sanna, Antonio [Max-Planck-Institute of Microstructure Physics, Halle (Saale) (Germany)

2013-07-01

The Eliashberg theory of superconductivity allows to describe materials with strong pairing interaction. In the non magnetic case it leads to a system of coupled integral multidimensional equations. Computational costs are usually reduced by an isotropic limit, and by restricting the Coulomb interaction to the use of one single parameter, μ{sup *}, often chosen to give the experimental T{sub c}. In this work we present the parameter-free approach in which the screened Coulomb interaction fully accounted within the Random Phase Approximation, entering the Eliashberg's equations on the same footing as the phononic interaction. We will compare this approach with Density Functional Theory for Superconductors where the corresponding approximation leads to a good agreement with experiments.

12. Feynman rules for Coulomb gauge QCD

International Nuclear Information System (INIS)

The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ–Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as ‘pseudo-Feynman’ integrals. We also explain how energy divergences cancel. - Highlights: ► In Coulomb gauge QCD, we re-express Christ–Lee terms in the Hamiltonian as pseudo-Feynman integrals. ► This gives a subgraph structure, and allows the ordinary renormalization process. ► It also leads to cancellation of energy-divergences.

13. Coulomb Bound States of Strongly Interacting Photons

Science.gov (United States)

Maghrebi, M. F.; Gullans, M. J.; Bienias, P.; Choi, S.; Martin, I.; Firstenberg, O.; Lukin, M. D.; Büchler, H. P.; Gorshkov, A. V.

2015-09-01

We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasibound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wave function resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.

14. Coulomb dissociation of $^{20,21}$N

CERN Document Server

Röder, Marko; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J G; Burgunder, G; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A; Farinon, F; Fraile, Luis M; Freer, Martin; Freudenberger, M; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Diaz, Diego Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Bleis, Tudi Le; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Caro, Magdalena Mostazo; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S; Plag, Ralf; Prochazka, A; Rahaman, Md Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Saez, Jose Sanchez del Rio; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G; Wimmer, Christine; Winfield, J S; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai

2016-01-01

Neutron-rich light nuclei and their reactions play an important role for the creation of chemical elements. Here, data from a Coulomb dissociation experiment on $^{20,21}$N are reported. Relativistic $^{20,21}$N ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ and $^{20}\\mathrm{N}(\\mathrm{n},\\gamma)^{21}\\mathrm{N}$ excitation functions and thermonuclear reaction rates have been determined. The $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ rate is up to a factor of 5 higher at $T<1$\\,GK with respect to previous theoretical calculations, leading to a 10\\,\\% decrease in the predicted fluorine abundance.

15. Coulomb bound states of strongly interacting photons

CERN Document Server

Maghrebi, M F; Bienias, P; Choi, S; Martin, I; Firstenberg, O; Lukin, M D; Büchler, H P; Gorshkov, A V

2015-01-01

We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wavefunction resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.

16. Coulomb interaction in Eliashberg theory of superconductivity

International Nuclear Information System (INIS)

The Eliashberg theory of superconductivity allows to describe materials with strong pairing interaction. In the non magnetic case it leads to a system of coupled integral multidimensional equations. Computational costs are usually reduced by an isotropic limit, and by restricting the Coulomb interaction to the use of one single parameter, μ*, often chosen to give the experimental Tc. In this work we present the parameter-free approach in which the screened Coulomb interaction fully accounted within the Random Phase Approximation, entering the Eliashberg's equations on the same footing as the phononic interaction. We will compare this approach with Density Functional Theory for Superconductors where the corresponding approximation leads to a good agreement with experiments.

17. Coulomb blockade at almost perfect transmission

OpenAIRE

Matveev, K. A.

1994-01-01

We study the equilibrium properties of a quantum dot connected to a bulk lead by a single-mode quantum point contact. The ground state energy and other thermodynamic characteristics of the grain show periodic dependence on the gate voltage (Coulomb blockade). We consider the case of almost perfect transmission, and show that the oscillations exist as long as the transmission coefficient of the contact is less than unity. Near the points where the dot charge is half-integer the thermodynamic c...

18. Chaos near the Coulomb barrier. Nuclear molecules

International Nuclear Information System (INIS)

The present work examines in detail the classical behavior of the α + 14C and the 12C + 12C(O+) collison at energies near the Coulomb barrier. The long-time motion of the compound nuclear system is identified in terms of its classical quasiperiodic and chaotic behavior. The consequences of this motion are discussed and interpreted in terms of the evolution of the system along a dynamical energy surface. 45 references

19. Lorenz or Coulomb in Galilean Electromagnetism ?

OpenAIRE

Rousseaux, Germain

2005-01-01

PDF version International audience Galilean Electromagnetism was discovered thirty years ago by Levy-Leblond & Le Bellac. However, these authors only explored the consequences for the fields and not for the potentials. Following De Montigny & al., we show that the Coulomb gauge condition is the magnetic limit of the Lorenz gauge condition whereas the Lorenz gauge condition applies in the electric limit of Lévy-Leblond & Le Bellac. Contrary to De Montigny & al. who used Galilean tensor c...

20. Coulomb drag in the mesoscopic regime

DEFF Research Database (Denmark)

Mortensen, N.A.; Flensberg, Karsten; Jauho, Antti-Pekka

2002-01-01

We present a theory for Coulomb drag between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

1. Coulomb drag in the mesoscopic regime

DEFF Research Database (Denmark)

Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka

2002-01-01

We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

2. Module of System Galactica with Coulomb's Interaction

Directory of Open Access Journals (Sweden)

Joseph J. Smulsky

2014-12-01

Full Text Available The system Galactica of free access is supplemented module for the Coulomb interaction. It is based on a high-precision method for solving differential equations of motion of N charged particles. The paper presents all the theoretical and practical issues required to use this module of system Galactica so that even the beginning researcher could study the motion of particles, atoms and molecules.

3. Coulomb dissociation studies for astrophysical thermonuclear reactions

Energy Technology Data Exchange (ETDEWEB)

Motobayashi, T. [Dept. of Physics, Rikkyo Univ., Toshima, Tokyo (Japan)

1998-06-01

The Coulomb dissociation method was applied to several radiative capture processes of astrophysical interest. The method has an advantage of high experimental efficiency, which allow measurements with radioactive nuclear beams. The reactions {sup 13}N(p,{gamma}){sup 14}O and {sup 7}Be(p,{gamma}){sup 8}B are mainly discussed. They are the key reaction in the hot CNO cycle in massive stars and the one closely related to the solar neutrino problem, respectively. (orig.)

4. Coulomb drag in the mesoscopic regime

DEFF Research Database (Denmark)

Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka

We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....

5. Dynamics of Coulombic and gravitational periodic systems

Science.gov (United States)

Kumar, Pankaj; Miller, Bruce N.

2016-04-01

We study the dynamics and the phase-space structures of Coulombic and self-gravitating versions of the classical one-dimensional three-body system with periodic boundary conditions. We demonstrate that such a three-body system may be reduced isomorphically to a spatially periodic system of a single particle experiencing a two-dimensional potential on a rhombic plane. For the case of both Coulombic and gravitational versions, exact expressions of the Hamiltonian have been derived in rhombic coordinates. We simulate the phase-space evolution through an event-driven algorithm that utilizes analytic solutions to the equations of motion. The simulation results show that the motion exhibits chaotic, quasiperiodic, and periodic behaviors in segmented regions of the phase space. While there is no evidence of global chaos in either the Coulombic or the gravitational system, the former exhibits a transition from a completely nonchaotic phase space at low energies to a mixed behavior. Gradual yet striking transitions from mild to intense chaos are indicated with changing energy, a behavior that differentiates the spatially periodic systems studied in this Rapid Communication from the well-understood free-boundary versions of the three-body problem. Our treatment of the three-body systems opens avenues for analysis of the dynamical properties exhibited by spatially periodic versions of various classes of systems studied in plasma and gravitational physics as well as in cosmology.

6. Elastic Coulomb breakup of $^{34}$Na

CERN Document Server

Singh, G; Chatterjee, R

2016-01-01

Purpose : The aim of this paper is to study the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb to give us a core of $^{33}$Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of $^{34}$Na. Method : A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb at 100 MeV/u. The triple differential cross-section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum and angular distributions as well as the average momenta, along with the energy-angular distributions. Results : The total one neutron removal cross-section is calculated to test the possible ground state configurations of $^{34}$Na. The average momentum results along with energy-angular calculations indicate $^{34}$Na to ha...

7. Off-energy-shell p-p scattering at sub-Coulomb energies via the Trojan horse method

International Nuclear Information System (INIS)

Two-proton scattering at sub-Coulomb energies has been measured indirectly via the Trojan horse method applied to the p + d→p + p + n reaction to investigate off-energy shell effects for scattering processes. The three-body experiment was performed at 5 and 4.7 MeV corresponding to a p-p relative energy ranging from 80 to 670 keV. The free p-p cross section exhibits a deep minimum right within this relative energy region due to Coulomb plus nuclear destructive interference. No minimum occurs instead in the Trojan horse p-p cross section, which was extracted by employing a simple plane-wave impulse approximation. A detailed formalism was developed to build up the expression of the theoretical half-off-shell p-p cross section. Its behavior agrees with the Trojan horse data and in turn formally fits the n-n, n-p, and nuclear p-p cross sections given the fact that in its expression the Coulomb amplitude is negligible with respect to the nuclear one. These results confirm the Trojan horse suppression of the Coulomb amplitude for scattering due to the off-shell character of the process

8. Self-consistent inclusion of classical large-angle Coulomb collisions in plasma Monte Carlo simulations

Energy Technology Data Exchange (ETDEWEB)

Turrell, A.E., E-mail: a.turrell09@imperial.ac.uk; Sherlock, M.; Rose, S.J.

2015-10-15

Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov–Fokker–Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products.

9. Self-consistent inclusion of classical large-angle Coulomb collisions in plasma Monte Carlo simulations

International Nuclear Information System (INIS)

Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov–Fokker–Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products

10. A Brief Comment on Multi-Gluon Amplitudes and Double Parton Interactions

CERN Document Server

Treleani, Daniele

2016-01-01

A typical contribution to a color ordered multi-gluon amplitude, which can split into two weakly correlated two-body gluon scattering amplitudes and may thus contribute to a Double Parton Interaction, is briefly discussed. We find that the color ordered amplitude is not enhanced in the typical configuration generated by a DPI, where the transverse momenta of final state gluons are compensated pairwise, while a dominant contribution to the multi-gluon amplitude is due to terms proportional to the fusion amplitude of two initial state gluons. Which corresponds to an amplitude effectively describing a two rather than a three-body partonic interaction.

11. The effect of electromagnetic structure of heavy ions below the Coulomb barrier

International Nuclear Information System (INIS)

The scattering of two charged bodies (such as heavy ions)at energies below the Coulomb barrier is considered. By solving the radial Schroedinger equation in a simple model it is found that the phase shifts are indeed close to those due to point charges, and the cross-section is very well reproduced by the Rutherford formula. The first-order Born approximation, however, differs violently from the corresponding Born amplitude due to point charges, and achievement of the Rutherford limit in the momentum space is a difficult task. A method of summing up the Born series is indicated and its evaluation in the semiclassical limit is suggested

12. Scalar-QED {Dirac_h}-corrections to the Coulomb potential

Energy Technology Data Exchange (ETDEWEB)

Helayel-Neto, J.A. [Centro Brasileiro de Pesquisas Fisica (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: helayel@cbpf.br; Penna-Firme, A.B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Faculdade de Educacao. E-mail: andrepf@cbpf.br; Shapiro, I.L. [Juiz de Fora Univ., MG (Brazil). Dept. de Fisica. E-mail: shapiro@fisica.ufjf.br

2000-05-01

The leading long-distance 1-loop quantum corrections to the Coulomb potential are derived for scalar QED and their gauge-independence is explicitly checked. The potential is obtained from the direct calculation of the 2-particle scattering amplitude, taking into account all relevant 1-loop diagrams. Our investigation should be regarded as first step towards the same programme for effective Quantum Gravity. In particular, with our calculation in the framework of scalar QED, we are able to demonstrate the incompleteness of some previous studies concerning the quantum Gravity counterpart. (author)

13. CHY formula and MHV amplitudes

CERN Document Server

Du, Yi-jian; Wu, Yong-shi

2016-01-01

In this paper, we study the relation between the Cachazo-He-Yuan (CHY) formula and the maximal-helicity-violating (MHV) amplitudes of Yang-Mills and gravity in four dimensions. We prove that only one special rational solution of the scattering equations found by Weinzierl support the MHV amplitudes. Namely, localized at this solution, the integrated CHY formula reproduces the Parke-Taylor formula for Yang-Mills amplitudes as well as the Hodges formula for gravitational amplitudes. This is achieved by developing techniques, in a manifestly M\\"obius covariant formalism, to explicitly compute relevant reduced Pfaffians/determinants. We observe and prove two interesting properties (or identities), which facilitate the computations. We also check that all the other $(n-3)!-1$ solutions to the scattering equations do not support the MHV amplitudes, and prove analytically that this is indeed true for the other special rational solution proposed by Weinzierl, that actually supports the anti-MHV amplitudes.

14. Hidden Beauty in Multiloop Amplitudes

OpenAIRE

Cachazo, Freddy(Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada); Spradlin, Marcus; Volovich, Anastasia

2006-01-01

Planar L-loop maximally helicity violating amplitudes in N = 4 supersymmetric Yang-Mills theory are believed to possess the remarkable property of satisfying iteration relations in L. We propose a simple new method for studying the iteration relations for four-particle amplitudes which involves the use of certain linear differential operators and eliminates the need to fully evaluate any loop integrals. We carry out this procedure in explicit detail for the two-loop amplitude and argue that t...

15. Amplitude oscillation of DCLC mode

International Nuclear Information System (INIS)

A quasilinear model and a simulation code taking into account the electron bounce resonance damping have been developed to describe the amplitude oscillation of the drift cyclotron loss-cone mode, which has been observed in mirror experiments. It was found that this oscillatory behavior of the amplitude is caused by the temporal variation of the growth rate and the effect of electron bounce resonance damping on the amplitude of this mode. (author)

16. Motivic amplitudes and cluster coordinates

OpenAIRE

J.K. Golden; Goncharov, A. B.; M. Spradlin; C. Vergu; Volovich, A.

2014-01-01

In this paper we study motivic amplitudes--objects which contain all of the essential mathematical content of scattering amplitudes in planar SYM theory in a completely canonical way, free from the ambiguities inherent in any attempt to choose particular functional representatives. We find that the cluster structure on the kinematic configuration space Conf_n(P^3) underlies the structure of motivic amplitudes. Specifically, we compute explicitly the coproduct of the two-loop seven-particle MH...

17. Graviton amplitudes from collinear limits of gauge amplitudes

OpenAIRE

Stephan Stieberger; Taylor, Tomasz R.

2015-01-01

We express all tree-level graviton amplitudes in Einstein's gravity as the collinear limits of a linear combination of pure Yang–Mills amplitudes in which each graviton is represented by two gauge bosons, each of them carrying exactly one half of graviton's momentum and helicity.

18. Heavy ion reactions around the Coulomb barrier

Institute of Scientific and Technical Information of China (English)

2011-01-01

The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The ex perimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the Coulomb barrier are measured and analyzed within a semi-classical model. The obvious effect of positive Q-value multi-neutron transfers on the sub-barrier fusion enhancement is observed in the 32S+96Zr system. In addition, the excitation functions of quasi-elastic scattering at a backward angle have been measured with high precision for the systems of 16O+208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. Considering the deformed coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. The elastic scattering angular distribution of 17F+12C at 60 MeV is measured and calculated by using the continuum-discretized coupled-channels (CDCC) approach. It is found that the diffuseness parameter of the real part of core-target potential has to be increased by 20% to reproduce the experimental result, which corresponds to an increment of potential depth at the surface re gion. The breakup cross section and the coupling between breakup and elastic scattering are small.

19. Coulomb drag in multiwall armchair carbon nanotubes

DEFF Research Database (Denmark)

Lunde, A.M.; Jauho, Antti-Pekka

2004-01-01

We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...

20. Coulomb field in a constant electromagnetic background

CERN Document Server

2016-01-01

Nonlinear Maxwell equations are written up to the third-power deviations from a constant-field background, valid within any local nonlinear electrodynamics including QED with Euler-Heisenberg effective Lagrangian. Linear electric response to imposed static finite-sized charge is found in the vacuum filled by an arbitrary combination of constant and homogeneous electric and magnetic fields. The modified Coulomb field, corrections to the total charge and to the charge density are given in terms of derivatives of the effective Lagrangian with respect to the field invariants.

1. Dynamic properties of the Coulomb fission

International Nuclear Information System (INIS)

The heavy ion induced fission after quasi-elastic scattering was studied in the systems 208Pb -> 238U for central collision at energies below the Coulomb barrier and 238U -> 238U for peripheral collisions at scattering angles smaller than the grazing angle. The dynamical properties and the phase-space distributions of the reactions could be determined by the method of the kinematical coincidences where positions and time-of-flight of two fission fragments and a scattered projectile-like nucleus were measured at the same time in large-area gas-filled parallel plate counters. (orig./HSI)

2. Multiple Coulomb scattering in thin silicon

International Nuclear Information System (INIS)

We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50–140 μm) silicon targets. The data were obtained with the EUDET telescope Aconite at DESY and are compared to parametrisations as used in the Geant4 software package. We find good agreement between data and simulation in the scattering distribution width but large deviations in the shape of the distribution. In order to achieve a better description of the shape, a new scattering model based on a Student's t distribution is developed and compared to the data

3. Resonances in the two centers Coulomb system

Energy Technology Data Exchange (ETDEWEB)

Seri, Marcello

2012-09-14

In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.

4. Expectation values in relativistic Coulomb problems

Energy Technology Data Exchange (ETDEWEB)

Suslov, Sergei K, E-mail: sks@asu.ed [School of Mathematical and Statistical Sciences and Mathematical, Computational, and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1804 (United States)

2009-09-28

We evaluate the matrix elements (Or{sup p}), where O = {l_brace}, {beta},i{alpha}n{beta}{r_brace} are the standard Dirac matrix operators and the angular brackets denote the quantum-mechanical average for the relativistic Coulomb problem, in terms of generalized hypergeometric functions {sub 3}F{sub 2}(1) for all suitable powers. Their connections with the Chebyshev and Hahn polynomials of a discrete variable are emphasized. As a result, we derive two sets of Pasternack-type matrix identities for these integrals, when p -> -p - 1 and p -> -p - 3, respectively. Some applications to the theory of hydrogenlike relativistic systems are reviewed.

5. Ordering transitions induced by Coulomb interactions

International Nuclear Information System (INIS)

We briefly review recent progress in treating phase transitions to ordered states driven by Coulomb interactions. Wigner crystallization of the one-component plasma, in the degenerate Fermi limit and in the classical limit, is the foremost example and developments in its theory are discussed in some detail. Attention is also given to quasi-twodimensional realizations of the plasma model in the laboratory. The usefulness of these ideas in relation to freezing and ordering transitions is illustrated with reference to alkali metals, elemental and polar semiconductors, and various types of ionic systems (molten salts, colloidal suspensions and astrophysical plasmas). (author). 70 refs, 5 figs

6. Feynman rules for Coulomb gauge QCD

CERN Document Server

Andrasi, A

2012-01-01

The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the subgraph structure of ordinary Feynamn graphs. The CL terms do not have subgraph structure. We show how to carry out enormalization in the presene of CL erms, by re-expressing these as pseudo-Feynman' inegrals. We also explain how energy divergences cancel.

7. Overlap Quark Propagator in Coulomb Gauge QCD

CERN Document Server

2014-01-01

The chirally symmetric Overlap quark propagator is explored in Coulomb gauge. This gauge is well suited for studying the relation between confinement and chiral symmetry breaking, since confinement can be attributed to the infrared divergent Lorentz-vector dressing function. Using quenched gauge field configurations on a $20^4$ lattice, the quark propagator dressing functions are evaluated, the dynamical quark mass is extracted and the chiral limit of these quantities is discussed. By removing the low-lying modes of the Dirac operator, chiral symmetry is artificially restored. Its effect on the dressing functions is discussed.

8. Electroweak Sudakov logarithms in the Coulomb gauge

OpenAIRE

Beenakker, W.; Werthenbach, A.

2000-01-01

We describe a formalism for calculating electroweak Sudakov logarithms in the Coulomb gauge. This formalism is applicable to arbitrary electroweak processes. For illustration we focus on the specific reactions e^+e^- -> f \\bar{f} and e^+e^- -> W_T^+W_T^-, W_L^+W_L^-, which contain all the salient details of dealing with the various types of particles. We discuss an explicit two-loop calculation and have a critical look at the (non-)exponentiation and factorisation properties of the Sudakov lo...

9. Resonances in the two centers Coulomb system

International Nuclear Information System (INIS)

In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.

10. Action principle for Coulomb collisions in plasmas

CERN Document Server

Hirvijoki, Eero

2015-01-01

In this letter we derive an action principle for Coulomb collisions in plasmas. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth potentials. Exact conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles. Being suitable for discretization, the presented action allows construction of variational integrators. Numerical implementation is left for a future study.

11. Static color-Coulomb force from restriction to Gribov region

International Nuclear Information System (INIS)

The static color-Coulomb interaction potential is determined as the solution of a non-linear integral equation. This equation expresses a self-consistency condition which arises in the Coulomb Hamiltonian formulation of lattice gauge theory when the restriction to the interior of the Gribov horizon is implemented. The potential obtained is in qualitatively agreement with expectations, being Coulombic with logarithmic corrections at short range, and confining at long range. (author)

12. Coulomb sum rules in the relativistic Fermi gas model

International Nuclear Information System (INIS)

Coulomb sum rules are studied in the framework of the Fermi gas model. A distinction is made between mathematical and observable sum rules. Differences between non-relativistic and relativistic Fermi gas predictions are stressed. A method to deduce a Coulomb response function from the longitudinal response is proposed and tested numerically. This method is applied to the 40Ca data to obtain the experimental Coulomb sum rule as a function of momentum transfer

13. Vacuum structure of the Coulomb gas in two dimensions

International Nuclear Information System (INIS)

We study the plasma phase of the two-dimensional Coulomb gas in the small density limit. The analysis is done using the correspondence of the Coulomb gas with the 1 + 1 sine-Gordon model, which has been exactly solved by the quantum inverse method. We construct the correct vacuum of the field theory, improving the former results. We obtain exact results for the Coulomb gas, which confirm the previous perturbative calculations. (orig.)

14. Coulomb corrections for interferometry analysis of expanding hadron systems

International Nuclear Information System (INIS)

The problem of the Coulomb corrections to the two-boson correlation functions for the systems formed in ultra-relativistic heavy ion collisions is considered for large effective system volumes. The modification of the standard zero-distance correction (so called Gamow or Coulomb factor) has been proposed for such a kind of systems. For the π+π+ and K+K+ correlation functions the analytical calculations of the Coulomb correction are compared with the exact numerical results. (author)

15. Large amplitude oscillatory elongation flow

DEFF Research Database (Denmark)

Rasmussen, Henrik K.; Laillé, Philippe; Yu, Kaijia

2008-01-01

A filament stretching rheometer (FSR) was used for measuring the elongation flow with a large amplitude oscillative elongation imposed upon the flow. The large amplitude oscillation imposed upon the elongational flow as a function of the time t was defined as epsilon(t) =(epsilon) over dot(0)t...

16. The mystery of Coulomb friction in sediment transport

Science.gov (United States)

Pähtz, Thomas; Duran, Orencio

Nearly all analytical models of sediment transport in Newtonian fluid (e.g., air or water) are based on Bagnold's assumption of a constant Coulomb friction coefficient (particle-shear-pressure-ratio, μ) at the interface (zb) between sediment bed and transport layer. In fact, this assumption is the main reason why these models predict the sediment load (and subsequently the sediment transport rate) to be proportional to the excess shear stress (τ -τt), a scaling which has been confirmed in many wind-tunnel and flume experiments. Attempts to explain why μ (zb) is constant have usually been based on the sliding-friction analogy or rheology arguments. However, here we analytically derive μ (zs) √{ 3} - 1 , where zs is the location at which the production rate of particle fluctuation energy is maximal. Our derivation is based on the assumption that the rate of collisional transfer of horizontal into vertical kinetic energy is typically much larger than the rate of energy dissipation. Using state-of-the-art numerical simulations of sediment transport in Newtonian fluid, we validate all assumptions and approximation involved in our derivation. Interestingly, the location zs can significantly deviate from zb depending on the simulated conditions. We acknowledge support from grants National Natural Science Foundation of China (Nos. 1151101041 and 41376095) and Natural Science Foundation of Zhejiang Province (No. LR16E090001).

17. Effect of Coulomb interaction on multi-electronwave packet dynamics

Energy Technology Data Exchange (ETDEWEB)

Shiokawa, T. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571 (Japan); Takada, Y. [Faculty of Engineering, Tokyo University of Science, Chiyoda, Tokyo, 102-0073, Japan and CREST, Japan Science and Technology Agency (Japan); Konabe, S.; Hatsugai, Y. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and CREST, Japan Science and Technology Agency (Japan); Muraguchi, M. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and CREST, Japan Science and Technology Agency (Japan); Endoh, T. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and Center for Spintronics Integrated Systems, Tohoku University, Sendai, 980-8577, Japan and CREST, Japan Science and Technology Agency (Japan); Shiraishi, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and Center for Computational Science, University of Tsukuba, Tsukuba, 305-8577, Japan and CREST, Japan Science and Technology Agency (Japan)

2013-12-04

We have investigated the effect of Coulomb interaction on electron transport in a one-dimensional nanoscale structure using a multi-electron wave packet approach. To study the time evolution, we numerically solve the time-dependent Hartree-Fock equation, finding that the electron wave packet dynamics strongly depends on the Coulomb interaction strength. When the Coulomb interaction is large, each electron wave packet moves separately in the presence of an electric field. With weak Coulomb interaction, however, the electron wave packets overlap, forming and moving as one collective wave packet.

18. Coulomb excitation of radioactive {sup 79}Pb

Energy Technology Data Exchange (ETDEWEB)

Lister, C.J.; Blumenthal, D.; Davids, C.N. [and others

1995-08-01

The technical challenges expected in experiments with radioactive beams can already be explored by using ions produced in primary reactions. In addition, the re-excitation of these ions by Coulomb excitation allows a sensitive search for collective states that are well above the yrast line. We are building an experiment to study Coulomb excitation of radioactive ions which are separated from beam particles by the Fragment Mass Analyzer. An array of gamma detectors will be mounted at the focal plane to measure the gamma radiation following re-excitation. Five Compton-suppressed Ge detectors and five planar LEPS detectors will be used. The optimum experiment of this type appears to be the study of {sup 79}Rb following the {sup 24}Mg ({sup 58}Ni,3p) reaction. We calculate that about 5 x 10{sup 5} {sup 79}Rb nuclei/second will reach the excitation foil. This rubidium isotope was selected for study as it is strongly produced and is highly deformed, so easily re-excited. The use of a {sup 58}Ni re-excitation foil offers the best yields. After re-excitation the ions will be subsequently transported into a shielded beamdump to prevent the accumulation of activity.

19. Coulomb dissociation in nonrelativistic and relativistic collisions

International Nuclear Information System (INIS)

Electromagnetic excitations in the Coulomb field of nuclei have been studied using quantum as well as semiclassical methods. Even at relatively modest incident energies, the Coulomb dissociation cross sections of projectiles with relatively low particle thresholds could be of sizeable order of magnitude. Such a study complements our knowledge about radiative capture processes, which are of interest for nuclear astrophysics. Quite a few questions remain to be answered, like the importance of nuclear interactions for small angle scattering, interference of different multipolarities for triple differentiial cross sections and distortion effects on the three-body final states. In the case of dissociation at relativistic energies it is shown that only for the total cross section both semiclassical and quantim-mechanical methods yield the same results. As an example the Primakoff effect is considered, where in an M1 excitation of ≅ 80 MeV a Λ hyperion is converted into a Σo hyperion by means of the virtual photon field of heavy target nuclei. Virtual photon spectra for all multipolarities can be calculated. This provides a sound basis for the analysis of electromagnetic dissociation experiments at relativistic heavy ion accelerators, like the BEVALAC. 10 figs., 25 refs

20. Elastic scattering of vortex electrons provides direct access to the Coulomb phase

CERN Document Server

Ivanov, I P; Surzhykov, A; Fritzsche, S

2016-01-01

Vortex electron beams are freely propagating electron waves carrying adjustable orbital angular momentum with respect to the propagation direction. Such beams were experimentally realized just a few years ago and are now used to probe various electromagnetic processes. So far, these experiments used the single vortex electron beams, either propagating in external fields or impacting a target. Here, we investigate the elastic scattering of two such aligned vortex electron beams and demonstrate that this process allows one to experimentally measure features which are impossible to detect in the usual plane-wave scattering. The scattering amplitude of this process is well approximated by two plane-wave scattering amplitudes with different momentum transfers, which interfere and give direct experimental access to the Coulomb phase. This phase (shift) affects the scattering of all charged particles and has thus received significant theoretical attention but was never probed experimentally. We show that a properly ...

1. Coherence, interference and the Pauli principle: Coulomb scattering of carbon from carbon

International Nuclear Information System (INIS)

When nuclei are scattered from each other at energies far below the Coulomb barrier, the angular distribution of the scattered intensity does not necessarily correspond to the familiar sin-4 1/2theta dependence of Rutherford scattering. When projectile and target nuclei are of the same kind, pronounced angular oscillations are generated by quantum interference of the two coherent amplitudes f(theta) and f(π-theta). The relative sign of the two amplitudes is given by the Pauli principle, i.e. by whether the identical particles are bosons or fermions. This article describes the observation and interpretation of such quantum interference effects in scattering processes with nuclei of the carbon isotopes 12C and 13C. All the data shown were taken by students with no previous training in the field. The educational aspects are emphasised of this realistic version of the famous 'two slits' Gedanken experiment. (author)

2. CHY formula and MHV amplitudes

Science.gov (United States)

Du, Yi-Jian; Teng, Fei; Wu, Yong-Shi

2016-05-01

In this paper, we study the relation between the Cachazo-He-Yuan (CHY) formula and the maximal-helicity-violating (MHV) amplitudes of Yang-Mills and gravity in four dimensions. We prove that only one special rational solution of the scattering equations found by Weinzierl supports the MHV amplitudes. Namely, localized at this solution, the integrated CHY formula produces the Parke-Taylor formula for MHV Yang-Mills amplitudes as well as the Hodges formula for MHV gravitational amplitudes, with an arbitrary number of external gluons/gravitons. This is achieved by developing techniques, in a manifestly Möbius covariant formalism, to explicitly compute relevant reduced Pfaffians/determinants. We observe and prove two interesting properties (or identities), which facilitate the computations. We also check that all the other ( n - 3)! - 1 solutions to the scattering equations do not support the MHV amplitudes, and prove analytically that this is indeed true for the other special rational solution proposed by Weinzierl, that actually supports the anti-MHV amplitudes. Our results reveal a mysterious feature of the CHY formalism that in Yang-Mills and gravity theory, solutions of scattering equations, involving only external momenta, somehow know about the configuration of external polarizations of the scattering amplitudes.

3. Cluster Functions and Scattering Amplitudes for Six and Seven Points

CERN Document Server

Harrington, Thomas

2015-01-01

Scattering amplitudes in planar super-Yang-Mills theory satisfy several basic physical and mathematical constraints, including physical constraints on their branch cut structure and various empirically discovered connections to the mathematics of cluster algebras. The power of the bootstrap program for amplitudes is inversely proportional to the size of the intersection between these physical and mathematical constraints: ideally we would like a list of constraints which determine scattering amplitudes uniquely. We explore this intersection quantitatively for two-loop six- and seven-point amplitudes by providing a complete taxonomy of the Gr(4,6) and Gr(4,7) cluster polylogarithm functions of arXiv:1401.6446 at weight 4.

4. Amplitude sorting of oscillatory burst signals by sampling

Science.gov (United States)

Davis, Thomas J.

1977-01-01

A method and apparatus for amplitude sorting of oscillatory burst signals is described in which the burst signal is detected to produce a burst envelope signal and an intermediate or midportion of such envelope signal is sampled to provide a sample pulse output. The height of the sample pulse is proportional to the amplitude of the envelope signal and to the maximum burst signal amplitude. The sample pulses are fed to a pulse height analyzer for sorting. The present invention is used in an acoustic emission testing system to convert the amplitude of the acoustic emission burst signals into sample pulse heights which are measured by a pulse height analyzer for sorting the pulses in groups according to their height in order to identify the material anomalies in the test material which emit the acoustic signals.

5. Collision between two ortho-positronium (Ps) atoms: A four-body Coulomb problem

RAY HASI

2016-05-01

The elastic collision between two ortho-positronium (e.g. $S = 1$) atoms is studied using an {\\it ab-initio} static exchange model (SEM) in the centre of mass (CM) frame by considering the system as a four-body Coulomb problem where all the Coulomb interaction terms in the direct and exchange channels are treated exactly. A coupled channel methodology in momentum space is used to solve Lippman–Schwinger equation following the integral approach. A new SEM code is developed in which the Born–Oppenheimer (BO) scattering amplitude acts as input to derive the SEM amplitude adapting the partial wave analysis. The $s$-, $p$- and $d$-wave elastic phase shifts and the corresponding partial cross-sections for the spin alignment $S = 0$, i.e., singlet (+) and $S = 2$, i.e., triplet (−) states are studied. An augmented Born approximation is used to includethe contribution of higher partial waves more accurately to determine the total/integrated elastic cross-section $(\\sigma)$, the quenching cross-section (σq) and ortho-to-para conversion ratio $(\\sigma/\\sigma q)$. The effective range theory is used to determine the scattering lengths and effective ranges in the s-wave elastic scattering. The theory includes the non-adiabatic short-range effects due to exchange.

6. Teleporting Superpositions of Chiral Amplitudes

CERN Document Server

Maierle, C S; Harris, R A; Maierle, Christopher S.; Lidar, Daniel A.; Harris, Robert A.

1998-01-01

Chiral molecules may exist in superpositions of left- and right-handed states. We show how the amplitudes of such superpositions may be teleported to the polarization degrees of freedom of a photon. Two experimental schemes are proposed, one leading to perfect, the other to state-dependent teleportation. Both methods yield complete information about the amplitudes. This is the first explicit example of "inter-species" teleportation, where the amplitudes of the quantum superposition of one species are transferred at the end of the process to a different species. The latter is then easily accessible for measurement.

7. Elastic Coulomb breakup of 34Na

Science.gov (United States)

Singh, G.; Shubhchintak, Chatterjee, R.

2016-08-01

Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our

8. Positive Amplitudes In The Amplituhedron

CERN Document Server

Arkani-Hamed, Nima; Trnka, Jaroslav

2014-01-01

The all-loop integrand for scattering amplitudes in planar N = 4 SYM is determined by an "amplitude form" with logarithmic singularities on the boundary of the amplituhedron. In this note we provide strong evidence for a new striking property of the superamplitude, which we conjecture to be true to all loop orders: the amplitude form is positive when evaluated inside the amplituhedron. The statement is sensibly formulated thanks to the natural "bosonization" of the superamplitude associated with the amplituhedron geometry. However this positivity is not manifest in any of the current approaches to scattering amplitudes, and in particular not in the cellulations of the amplituhedron related to on-shell diagrams and the positive grassmannian. The surprising positivity of the form suggests the existence of a "dual amplituhedron" formulation where this feature would be made obvious. We also suggest that the positivity is associated with an extended picture of amplituhedron geometry, with the amplituhedron sitting...

9. Scattering amplitudes in gauge theories

CERN Document Server

Henn, Johannes M

2014-01-01

At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge.   These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum ...

10. Model selection for amplitude analysis

International Nuclear Information System (INIS)

Model complexity in amplitude analyses is often a priori under-constrained since the underlying theory permits a large number of possible amplitudes to contribute to most physical processes. The use of an overly complex model results in reduced predictive power and worse resolution on unknown parameters of interest. Therefore, it is common to reduce the complexity by removing from consideration some subset of the allowed amplitudes. This paper studies a method for limiting model complexity from the data sample itself through regularization during regression in the context of a multivariate (Dalitz-plot) analysis. The regularization technique applied greatly improves the performance. An outline of how to obtain the significance of a resonance in a multivariate amplitude analysis is also provided

11. Analytization of elastic scattering amplitude

CERN Document Server

Troshin, S M

2016-01-01

Dependence of the real part of the elastic scattering amplitude on the transferred momentum -t at the asymptotical energies has been restored from the corresponding imaginary part on the basis of derivative analyticity relations (analytization).

12. Spherical Calogero model with oscillator/Coulomb potential: quantum case

CERN Document Server

Correa, Francisco; Lechtenfeld, Olaf; Nersessian, Armen

2016-01-01

We consider the quantum mechanics of Calogero models in an oscillator or Coulomb potential on the N-dimensional sphere. Their Hamiltonians are obtained by an appropriate Dunkl deformation of the oscillator/Coulomb system on the sphere and its restriction to (Coxeter reflection) symmetric wave functions. By the same method we also find the symmetry generators and compute their algebras.

13. Coulomb interaction between a spherical and a deformed nuclei

CERN Document Server

Takigawa, N; Ihara, N; Takigawa, Noboru; Rumin, Tamanna; Ihara, Naoki

2000-01-01

We present analytic expressions of the Coulomb interaction between a spherical and a deformed nuclei which are valid for all separation distance. We demonstrate their significant deviations from commonly used formulae in the region inside the Coulomb radius, and show that they remove various shortcomings of the conventional formulae.

14. Coulomb corrections in the low-energy scattering

International Nuclear Information System (INIS)

Renormalization of the coefficients of the ''effective range expansion'' is considered for the short-range Coulomb problem. The exactly solvable model of the Coulomb plus short range potential is considered. Exact solutions are compared with approximations frequently used in the theory of hadronic atoms

15. Effect of operational parameters on Coulombic efficiency in bioelectrochemical systems

NARCIS (Netherlands)

Sleutels, T.H.J.A.; Darus, L.; Hamelers, H.V.M.; Buisman, C.J.N.

2011-01-01

To create an efficient bioelectrochemical system, a high Coulombic efficiency is required. This efficiency is a direct measure for the competition between electrogens and methanogens when acetate is used as substrate. In this study the Coulombic efficiency in a microbial electrolysis cell was invest

16. Correlated Coulomb drag in capacitively coupled quantum-dot structures

DEFF Research Database (Denmark)

Kaasbjerg, Kristen; Jauho, Antti-Pekka

2016-01-01

We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach which accounts for higher-order tunneling (cotunneli...

17. Antilocalization of Coulomb Blockade in a Ge-Si Nanowire

DEFF Research Database (Denmark)

Higginbotham, Andrew P.; Kuemmeth, Ferdinand; Larsen, Thorvald Wadum;

2014-01-01

The distribution of Coulomb blockade peak heights as a function of magnetic field is investigated experimentally in a Ge-Si nanowire quantum dot. Strong spin-orbit coupling in this hole-gas system leads to antilocalization of Coulomb blockade peaks, consistent with theory. In particular, the peak...

18. Coulomb blockade of spin-dependent shuttling

Science.gov (United States)

Park, Hee Chul; Kadigrobov, Anatoli M.; Shekhter, Robert I.; Jonson, M.

2013-12-01

We show that nanomechanical shuttling of single electrons may enable qualitatively new functionality if spin-polarized electrons are injected into a nanoelectromechanical single-electron tunneling (NEM-SET) device. This is due to the combined effects of spin-dependent electron tunneling and Coulomb blockade of tunneling, which are phenomena that occur in certain magnetic NEM-SET devices. Two effects are predicted to occur in such structures. The first is a reentrant shuttle instability, by which we mean the sequential appearance, disappearance and again the appearance of a shuttle instability as the driving voltage is increased (or the mechanical dissipation is diminished). The second effect is an enhanced spin polarization of the nanomechanically assisted current flow.

19. Study on Coulomb explosions of ion mixtures

CERN Document Server

Boella, E; D'Angola, A; Coppa, G; Silva, L O

2015-01-01

The paper presents a theoretical work on the dynamics of Coulomb explosion for spherical nanoplasmas composed by two different ion species. Particular attention has been dedicated to study the energy spectra of the ions with the larger charge-to-mass ratio. The connection between the formation of shock shells and the energy spread of the ions has been the object of a detailed analysis, showing that under particular conditions the width of the asymptotic energy spectrum tends to become very narrow, which leads to a multi-valued ion phase-space. The conditions to generate a quasi mono-energetic ion spectrum have been rigorously demonstrated and verifed by numerical simulations, using a technique that, exploiting the spherical symmetry of the problem, allows one to obtain very accurate and precise results.

20. Gauge Theories on the Coulomb branch

CERN Document Server

Schwarz, John H

2014-01-01

We construct the world-volume action of a probe D3-brane in $AdS_5 \\times S^5$ with $N$ units of flux. It has the field content, symmetries, and dualities of the $U(1)$ factor of ${\\cal N} =4$ $U(N+1)$ super Yang--Mills theory, spontaneously broken to $U(N) \\times U(1)$ by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a highly effective action' (HEA). We construct an $SL(2,Z)$ multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that it reproduces the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a soliton bubble', which is interpreted as a phase boundary.

1. Relativistic Aharonov endash Bohm endash Coulomb problem

International Nuclear Information System (INIS)

The ((2+1)-dimensional) Aharonov endash Bohm effect is analyzed for a spin-1/2 particle in the case that a 1/r potential is present. Scalar and vector couplings are each considered. It is found that the approach in which the flux tube is given a finite radius that is taken to zero only after a matching of boundary conditions does not give physically meaningful results. Specifically, the operations of taking the limit of zero flux tube radius and the Galilean limit do not commute. Thus there appears to be no satisfactory solution of the relativistic Aharonov endash Bohm endash Coulomb problem using the finite radius flux tube method. Copyright copyright 1996 Academic Press, Inc

2. Coulomb dissociation of light unstable nuclei

Energy Technology Data Exchange (ETDEWEB)

Kido, Toshihiko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Yabana, Kazuhiro; Suzuki, Yoshiyuki

1997-05-01

The aim of this study is that a simulation method applicable to the atomic nucleus with neutron halo structure developed till now is applied to a wider range unstable nucleus containing proton excess nucleus to also attribute understanding of nuclear reaction with interest in astronomical nuclear reaction. The proton dissociation energy in {sup 8}B nucleus is small value of 138 eV, which is thought to have a structure of proton at the most outer shell bound much weakly by core nucleus and spread in thinner thickness. For the coulomb excitation of such weak bound system, quantum theoretical and non-perturbational treatment is important. Therefore, 3-dimensional time-dependent Schroedinger equation on relative wave function of the core nucleus {sup 7}Be and halo proton p will be dissolved in time space and will execute a time developmental simulation. (G.K.)

3. Multiple Coulomb excitation experiment of 68Zn

International Nuclear Information System (INIS)

Coulomb excitation experiment was carried out with a 68Zn beam bombarding a natPb target. Two E2 matrix elements and the quadrupole moment of the 21+ state were newly derived with the least-squares search code GOSIA. The potential energy surface (PES) was calculated with the Nilsson-Strutinsky model, showing two shallow minima: the first minimum does not contain the 1g9/2 orbit below the Fermi surface, while the second minimum does. The ground state band and the intruder band seem to be constructed on the first and the second minimum, respectively. As for the ground state band, the asymmetric rotor model and the IBM in O(6) limit reproduced the experimental values rather well. The shallow PES may suggest instability of the shape. The ground state band structure may be explained assuming a soft triaxial deformation

4. Simplistic Coulomb Forces in Molecular Dynamics

DEFF Research Database (Denmark)

Hansen, Jesper Schmidt; Schrøder, Thomas; Dyre, J. C.

2012-01-01

salt model the SF approximation overall reproduces the structural and dynamical properties as accurately as does the Wolf method. It is shown that the optimal Wolf damping parameter depends on the property in focus and that neither the potential energy nor the radial distribution function are useful...... measures for the convergence of the Wolf method to the Ewald summation method. The SF approximation is also tested for the SPC/Fw model of liquid water at room temperature, showing good agreement with both the Wolf and the particle mesh Ewald methods; this confirms previous findings [Fennell, C. J......In this paper we compare the Wolf method to the shifted forces (SF) method for efficient computer simulation of bulk systems with Coulomb forces, taking results from the Ewald summation and particle mesh Ewald methods as representing the true behavior. We find that for the Hansen–McDonald molten...

5. One loop multiphoton helicity amplitudes

CERN Document Server

Mahlon, G

1994-01-01

We use the solutions to the recursion relations for double-off-shell fermion currents to compute helicity amplitudes for $n$-photon scattering and electron-positron annihilation to photons in the massless limit of QED. The form of these solutions is simple enough to allow {\\it all}\\ of the integrations to be performed explicitly. For $n$-photon scattering, we find that unless $n=4$, the amplitudes for the helicity configurations (+++...+) and (-++...+) vanish to one-loop order.

6. Little String Amplitudes (and the Unreasonable Effectiveness of 6D SYM)

CERN Document Server

Chang, Chi-Ming; Shao, Shu-Heng; Wang, Yifan; Yin, Xi

2014-01-01

We study tree level scattering amplitudes of four massless states in the double scaled little string theory, and compare them to perturbative loop amplitudes in six-dimensional super-Yang-Mills theory. The little string amplitudes are computed from correlators in the cigar coset CFT and in N=2 minimal models. The results are expressed in terms of integrals of conformal blocks and evaluated numerically in the alpha' expansion. We find striking agreements with up to 2-loop scattering amplitudes of massless gluons in 6D SU(k) SYM at a Z_k invariant point on the Coulomb branch. We comment on the issue of UV divergence at higher loop orders in the gauge theory and discuss the implication of our results.

7. Motivic amplitudes and cluster coordinates

International Nuclear Information System (INIS)

In this paper we study motivic amplitudes — objects which contain all of the essential mathematical content of scattering amplitudes in planar SYM theory in a completely canonical way, free from the ambiguities inherent in any attempt to choose particular functional representatives. We find that the cluster structure on the kinematic configuration space Confn(ℙ3) underlies the structure of motivic amplitudes. Specifically, we compute explicitly the coproduct of the two-loop seven-particle MHV motivic amplitude A7,2M and find that like the previously known six-particle amplitude, it depends only on certain preferred coordinates known in the mathematics literature as cluster X-coordinates on Confn(ℙ3). We also find intriguing relations between motivic amplitudes and the geometry of generalized associahedrons, to which cluster coordinates have a natural combinatoric connection. For example, the obstruction to A7,2M being expressible in terms of classical polylogarithms is most naturally represented by certain quadrilateral faces of the appropriate associahedron. We also find and prove the first known functional equation for the trilogarithm in which all 40 arguments are cluster X-coordinates of a single algebra. In this respect it is similar to Abel’s 5-term dilogarithm identity

8. Coulomb excitation effects on alpha-particle optical potential below the Coulomb barrier

CERN Document Server

Avrigeanu, V; Mănăilescu, C

2016-01-01

A competition of the low-energy Coulomb excitation (CE) with the compound nucleus (CN) formation in alpha-induced reactions below the Coulomb barrier has recently been assumed in order to make possible the description of the latter as well as the alpha-particle emission by the same optical model (OM) potential. On the contrary, we show in the present work that the corresponding partial waves and integration radii provide evidence for the distinct account of the CE cross section and OM total-reaction cross section $\\sigma_R$. Thus the largest contribution to CE cross section comes by far from partial waves larger than the ones contributing to the $\\sigma_R$ values.

9. Coulomb vs. physical string tension on the lattice

CERN Document Server

Burgio, G; Reinhardt, H; Vogt, H

2015-01-01

We investigate the precise relationship between the Coulomb and the physical (Wilson) string tension on the lattice, as the former is generally known to give an upper bound for the latter. We give evidence that the two string tensions are in a one to one correspondence at zero temperature, while they become unrelated at finite temperatures. More precisely, we show that the standard lattice calculations of the Coulomb gauge confinement scenario are always tied to the spatial string tension, which is known to survive the deconfinement phase transition and to cause screening effects in the quark-gluon plasma. Our analysis is based on the identification and elimination of center vortices which allows to control the physical string tension and study its effect on the Coulomb gauge observables. We also show how alternative definitions of the Coulomb potential may sense the deconfinement transition, although a true static Coulomb gauge order parameter for the phase transition is still elusive on the lattice.

10. The Coulomb potential in quantum mechanics and related topics

International Nuclear Information System (INIS)

This dissertation consists of an analytic study of the Coulomb interaction in nonrelativistic quantum mechanics and some related topics. The author investigates in a number of self-contained articles various interesting and important properties of the Coulomb potential. Some of these properties are shared by other potentials which also play a role in quantum mechanics. For such related interactions a comparative study is made. The principal difficulties in the description of proton-deuteron scattering and break-up reactions, due to the Coulomb interaction, are studied by working out a simple model. The bound states are studied for the Coulomb plus Yamaguchi potential, for the symmetric shifted Coulomb potential, and for local potentials with an inverse-distance-squared asymptotic behaviour. (Auth.)

11. Proportional Reasoning and the Visually Impaired

Science.gov (United States)

Hilton, Geoff; Hilton, Annette; Dole, Shelley L.; Goos, Merrilyn; O'Brien, Mia

2012-01-01

Proportional reasoning is an important aspect of formal thinking that is acquired during the developmental years that approximate the middle years of schooling. Students who fail to acquire sound proportional reasoning often experience difficulties in subjects that require quantitative thinking, such as science, technology, engineering, and…

12. Tritium measurement with a proportional counter

International Nuclear Information System (INIS)

The purpose of this study is to investigate a feasibility of real-time measurement of tritium concentration with a proportional counter. For the purpose, we constructed a flow-through type of proportional counter. The characteristics of the counter for seven gases, PR, H2, D2, Ar, CH4, N2, and air, were investigated to research appropriate gases. (author)

13. Prospective Elementary School Teachers' Proportional Reasoning

Science.gov (United States)

Valverde, Gabriela; Castro, Encarnación

2012-01-01

We present the findings of a study on prospective elementary teachers' proportional reasoning. After describing some of the teachers' performance in solving multiplicative structure problems that involve ratios and relations of direct proportionality between quantities, we were able to establish classifications of their answers according to…

14. Cold transfer between deformed, Coulomb excited nuclei; Kalter Transfer zwischen deformierten, Coulomb-angeregten Kernen

Energy Technology Data Exchange (ETDEWEB)

Bauer, H.

1998-12-31

The scattering system {sup 162}Dy {yields} {sup 116}Sn has been examined at energies in the vicinity of the Coulomb barrier using the Heidelberg-Darmstadt Crystal Ball spectrometer combined with 5 Germanium-CLUSTER detectors. In order to study pairing correlations as a function of angular momentum cold events were selected in the 2n stripping channel by identifying and suppressing the dominant hot part of the transfer with the Crystal Ball. The CLUSTER detectors with their high {gamma}-efficiency were used to identify the transfer channel and to resolve individual final states. Cross sections for the population of individual yrast states in a cold transfer reaction have been measured for the first time indicating the strong influence of higher transfer multipolarities. At small surface distances Coulomb-nuclear interferences were found to be responsible for the stronger decline of the population of higher yrast states in the transfer channel as compared to the Coulex channel. As a preparatory study for 2n transfer measurements between high spin yrast states in the backbending region of deformed nuclei the Coulomb excitation process in the crossing region of two bands in {sup 162}Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)

15. Human skeleton proportions from monocular data

Institute of Scientific and Technical Information of China (English)

PENG En; LI Ling

2006-01-01

This paper introduces a novel method for estimating the skeleton proportions ofa human figure from monocular data.The proposed system will first automatically extract the key frames and recover the perspective camera model from the 2D data.The human skeleton proportions are then estimated from the key frames using the recovered camera model without posture reconstruction. The proposed method is tested to be simple, fast and produce satisfactory results for the input data. The human model with estimated proportions can be used in future research involving human body modeling or human motion reconstruction.

16. Nonsinglet pentagons and NMHV amplitudes

Energy Technology Data Exchange (ETDEWEB)

Belitsky, A.V., E-mail: andrei.belitsky@asu.edu

2015-07-15

Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.

17. Nonsinglet pentagons and NMHV amplitudes

Directory of Open Access Journals (Sweden)

A.V. Belitsky

2015-07-01

Full Text Available Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.

18. Factorization of Chiral String Amplitudes

CERN Document Server

Huang, Yu-tin; Yuan, Ellis Ye

2016-01-01

We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: As found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.

19. Coulomb-Born calculation of the triple-differential cross section for inner-shell electron-impact ionization of carbon

International Nuclear Information System (INIS)

A Coulomb-Born approximation is used to compute the triple-differential cross section for electron-impact inner-shell (1s) ionization of carbon. We employ a perturbation series that allows the use of Coulomb waves with arbitrary Zeff for the incoming, scattered, and ejected electrons. Most of the features of the triple-differential cross section observed experimentally are reproduced, even though these wave functions are distorted by an effective Coulomb potential and therefore do not satisfy the plane-wave boundary conditions at infinity. In order to explain some features that appear in the cross section, and in order to probe the validity of a dipole approximation, we make a multipole expansion of the transition matrix and show that the amplitudes of the multipole components are similar to those obtained in the Born approximation, while the relative phases of the multipoles differ greatly

20. Proportional sharing assumption in tracing methodology

Energy Technology Data Exchange (ETDEWEB)

Bialek, J.W. [Edinburgh Univ. (United Kingdom). School of Engineering and Electronics; Kattuman, P.A. [Cambridge Univ. (United Kingdom). Judge Inst. of Management

2004-07-01

In order to overcome problems related to the marginal pricing of transmission costs, tracing methodology has been proposed as an alternative, most notably for transmission pricing of cross-border trades in Europe. The tracing methodology is based on the assumption that, at any network node, the incoming flows are proportionally distributed among the outcoming flows. This assumption can be neither proved nor disproved physically and the authors aim to rationalise it. The analysis presented here is of the loss allocation problem. First it is shown that the proportionality assumption leads to the cost allocation which is aggregation invariant. Then the proportional sharing principle is rationalised using game theory and the information theory. We show that the Shapley value solution concept, which satisfies all properties one may demand of a loss allocation scheme, substantiates the proportional sharing rule. We have also shown that the rule can be derived from the maximum entropy principle. (author)

1. Proportional sharing assumption in tracing methodology

International Nuclear Information System (INIS)

In order to overcome problems related to the marginal pricing of transmission costs, tracing methodology has been proposed as an alternative, most notably for transmission pricing of cross-border trades in Europe. The tracing methodology is based on the assumption that, at any network node, the incoming flows are proportionally distributed among the outcoming flows. This assumption can be neither proved nor disproved physically and the authors aim to rationalise it. The analysis presented here is of the loss allocation problem. First it is shown that the proportionality assumption leads to the cost allocation which is aggregation invariant. Then the proportional sharing principle is rationalised using game theory and the information theory. We show that the Shapley value solution concept, which satisfies all properties one may demand of a loss allocation scheme, substantiates the proportional sharing rule. We have also shown that the rule can be derived from the maximum entropy principle. (author)

2. Universal trading under proportional transaction costs

OpenAIRE

Martin, Richard J.

2016-01-01

The theory of optimal trading under proportional transaction costs has been considered from a variety of perspectives. In this paper, we show that all the results can be interpreted using a universal law, illustrating the results in trading algorithm design.

3. OPE for all Helicity Amplitudes

CERN Document Server

Basso, Benjamin; Cordova, Lucia; Sever, Amit; Vieira, Pedro

2014-01-01

We extend the Operator Product Expansion (OPE) for scattering amplitudes in planar N=4 SYM to account for all possible helicities of the external states. This is done by constructing a simple map between helicity configurations and so-called charged pentagon transitions. These OPE building blocks are generalizations of the bosonic pentagons entering MHV amplitudes and they can be bootstrapped at finite coupling from the integrable dynamics of the color flux tube. A byproduct of our map is a simple realization of parity in the super Wilson loop picture.

4. Proportionality and employment discrimination in the UK.

OpenAIRE

Baker, Aaron

2008-01-01

This paper argues that the justification defence in UK statutory indirect discrimination cases should incorporate proportionality as applied by the European Court of Human Rights (ECtHR). It first analyses the evolution of the UK approach to proportionality before the enactment of the Human Rights Act 1998 (HRA), when its primary influence was the jurisprudence of the European Court of Justice (ECJ) applying EC equal treatment directives. This assessment shows that the UK judiciary was alread...

5. Characterizing intra-exciton Coulomb scattering in terahertz excitations

International Nuclear Information System (INIS)

An intense terahertz field is applied to excite semiconductor quantum wells yielding strong non-equilibrium exciton distributions. Even though the relaxation channels involve a complicated quantum kinetics of Coulomb and phonon effects, distinct relaxation signatures of Coulomb scattering are identified within time-resolved photoluminescence by comparing the experiment with a reduced model that contains all relevant microscopic processes. The analysis uncovers a unique time scale for the Coulomb scattering directly from experiments and reveals the influence of phonon relaxation as well as radiative decay

6. Coulomb displacement energies in nuclei: a new approach

International Nuclear Information System (INIS)

The neutron core polarization gives rise to an important correction to the direct Coulomb contribution when one calculates the Coulomb displacement energies. In the Hartree-Fock model it is shown that this correction is about 2% to 4.5% in medium and heavy nuclei. The core polarization as well as other higher order effects can be included by using a selfconsistent description of the analog state in a complete proton particle-neutron hole space. The Coulomb displacement energies in 48Ca, 88Sr and 208Pb have been calculated using Skyrme interactions SIII and SIV. A good agreement with experiment is obtained

7. Ionic Coulomb Blockade and Resonant Conduction in Biological Ion Channels

CERN Document Server

Kaufman, I Kh; Eisenberg, R S

2014-01-01

The conduction and selectivity of calcium/sodium ion channels are described in terms of ionic Coulomb blockade, a phenomenon based on charge discreteness and an electrostatic model of an ion channel. This novel approach provides a unified explanation of numerous observed and modelled conductance and selectivity phenomena, including the anomalous mole fraction effect and discrete conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The model is equally applicable to other nanopores.

8. On Coulomb disintegration of relativistic nuclei and hypernuclei

International Nuclear Information System (INIS)

The dependence of the total cross-section of excitation and disintegration of a relativistic nucleus in the Coulomb field on the energy and parameters characterizing nuclear dimensions is investigated. The analogy with the problem of atomic ionization at the passage of charged particles through matter is used. The results are applied to the description of the Coulomb dissociation of nuclei with small binding energies. An explicit expression for the effective cross-section of the Coulomb disintegration of the hypernucleus-Λ3H into a deuteron and Λ-particle. 12 refs

9. Nuclear Interference effects in 8B sub-Coulomb breakup

OpenAIRE

Nunes, F. M.; Thompson, I.J.

1998-01-01

The breakup of $^8$B on $^{58}$Ni below the Coulomb barrier was measured recently with the aim of determining the Coulomb breakup components. We reexamine this reaction, and perform one step quantum-mechanical calculations that include E1, E2 and nuclear contributions. We show that the nuclear contribution is by no means negligible at the intermediate angular range where data was taken. Our results indicate that, for an accurate description of this reaction, Coulomb E1, E2 and nuclear process...

10. Deep inelastic scattering near the Coulomb barrier

Energy Technology Data Exchange (ETDEWEB)

Gehring, J.; Back, B.; Chan, K. [and others

1995-08-01

Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.

11. Accelerated Monte Carlo Methods for Coulomb Collisions

Science.gov (United States)

Rosin, Mark; Ricketson, Lee; Dimits, Andris; Caflisch, Russel; Cohen, Bruce

2014-03-01

We present a new highly efficient multi-level Monte Carlo (MLMC) simulation algorithm for Coulomb collisions in a plasma. The scheme, initially developed and used successfully for applications in financial mathematics, is applied here to kinetic plasmas for the first time. The method is based on a Langevin treatment of the Landau-Fokker-Planck equation and has a rich history derived from the works of Einstein and Chandrasekhar. The MLMC scheme successfully reduces the computational cost of achieving an RMS error ɛ in the numerical solution to collisional plasma problems from (ɛ-3) - for the standard state-of-the-art Langevin and binary collision algorithms - to a theoretically optimal (ɛ-2) scaling, when used in conjunction with an underlying Milstein discretization to the Langevin equation. In the test case presented here, the method accelerates simulations by factors of up to 100. We summarize the scheme, present some tricks for improving its efficiency yet further, and discuss the method's range of applicability. Work performed for US DOE by LLNL under contract DE-AC52- 07NA27344 and by UCLA under grant DE-FG02-05ER25710.

12. Electron attraction mediated by Coulomb repulsion

Science.gov (United States)

Hamo, A.; Benyamini, A.; Shapir, I.; Khivrich, I.; Waissman, J.; Kaasbjerg, K.; Oreg, Y.; von Oppen, F.; Ilani, S.

2016-07-01

One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed ‘excitonic’, promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the ‘glue’ that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.

13. Monopole defects and magnetic Coulomb blockade

International Nuclear Information System (INIS)

Magnetic monopoles, predicted by Dirac, entered a new paradigm with the discovery of emergent monopoles within dipole lattices known as bulk and artificial spin ices. The observation of monopoles in certain artificial systems, and their absence from other similar structures, is a significant puzzle. Connected artificial spin-ice structures attract much attention in terms of the possibility to read states electrically, and offer the possibility of monopole defect control via well-understood domain wall processes. Nevertheless, full comprehension of the underlying processes is lacking. Here, we establish one of the overriding components. We demonstrate using high-resolution scanning transmission x-ray microscopy (STXM) the cooperative process associated with two transverse domain walls that creates the monopole defect in NiFe. The feature size of the array is large compared to the exchange length in the ferromagnet, and the two transverse domain walls give a rich internal structure to the monopole defect vertex. The magnetic Coulomb repulsion between two domain walls carrying the same sign of magnetic charge stabilizes the monopole defects at fields greater than the depinning field for a single wall at that vertex. These observations allow us to form an overview of monopole defect control possibilities from extrinsic pinning as in Co arrays (the extreme extrinsic limit being isolated bar structures) to intrinsic pinning captured here.

14. Employing helicity amplitudes for resummation

Science.gov (United States)

Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.

2016-05-01

Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d -dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for p p →H +0 , 1, 2 jets, p p →W /Z /γ +0 , 1, 2 jets, and p p →2 , 3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e+e- and e-p collisions.

15. Positivity of spin foam amplitudes

International Nuclear Information System (INIS)

The amplitude for a spin foam in the Barrett-Crane model of Riemannian quantum gravity is given as a product over its vertices, edges and faces, with one factor of the Riemannian 10j symbols appearing for each vertex, and simpler factors for the edges and faces. We prove that these amplitudes are always nonnegative for closed spin foams. As a corollary, all open spin foams going between a fixed pair of spin networks have real amplitudes of the same sign. This means one can use the Metropolis algorithm to compute expectation values of observables in the Riemannian Barrett-Crane model, as in statistical mechanics, even though this theory is based on a real-time (eiS) rather than imaginary-time e-S path integral. Our proof uses the fact that when the Riemannian 10j symbols are nonzero, their sign is positive or negative depending on whether the sum of the ten spins is an integer or half-integer. For the product of 10j symbols appearing in the amplitude for a closed spin foam, these signs cancel. We conclude with some numerical evidence suggesting that the Lorentzian 10j symbols are always nonnegative, which would imply similar results for the Lorentzian Barrett-Crane model

16. Discontinuity formulas for multiparticle amplitudes

International Nuclear Information System (INIS)

It is shown how discontinuity formulas for multiparticle scattering amplitudes are derived from unitarity and analyticity. The assumed analyticity property is the normal analytic structure, which was shown to be equivalent to the space-time macrocausality condition. The discontinuity formulas to be derived are the basis of multi-particle fixed-t dispersion relations

17. Scattering amplitudes in gauge theories

International Nuclear Information System (INIS)

First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.

18. Employing Helicity Amplitudes for Resummation

CERN Document Server

Moult, Ian; Tackmann, Frank J; Waalewijn, Wouter J

2015-01-01

Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in $4$- and $d$-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard m...

19. Employing helicity amplitudes for resummation

International Nuclear Information System (INIS)

Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for pp → H+0,1,2 jets, pp → W/Z/γ+0,1,2 jets, and pp → 2,3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e+e- and e-p collisions.

20. N-loop string amplitude

International Nuclear Information System (INIS)

Work on the derivation of an explicit perturbation series for string and superstring amplitudes is reviewed. The light-cone approach is emphasized, but some work on the Polyakov approach is also mentioned, and the two methods are compared. The calculation of the measure factor is outlined in the interacting-string picture

1. N-loop string amplitude

Energy Technology Data Exchange (ETDEWEB)

Mandelstam, S.

1986-06-01

Work on the derivation of an explicit perturbation series for string and superstring amplitudes is reviewed. The light-cone approach is emphasized, but some work on the Polyakov approach is also mentioned, and the two methods are compared. The calculation of the measure factor is outlined in the interacting-string picture. (LEW)

2. Veneziano Amplitude for Winding Strings

OpenAIRE

Khuri, Ramzi R.

1993-01-01

String configurations with nonzero winding number describe soliton string states. We compute the Veneziano amplitude for the scattering of arbitrary winding states and show that in the large radius limit the strings always scatter trivially and with no change in the individual winding numbers of the strings. In this limit, then, these states scatter as true solitons.

3. Discontinuity formulas for multiparticle amplitudes

Energy Technology Data Exchange (ETDEWEB)

Stapp, H.P.

1976-03-01

It is shown how discontinuity formulas for multiparticle scattering amplitudes are derived from unitarity and analyticity. The assumed analyticity property is the normal analytic structure, which was shown to be equivalent to the space-time macrocausality condition. The discontinuity formulas to be derived are the basis of multi-particle fixed-t dispersion relations.

4. Proportion congruency effects: Instructions may be enough

Directory of Open Access Journals (Sweden)

Olga eEntel

2014-10-01

Full Text Available Learning takes time, namely, one needs to be exposed to contingency relations between stimulus dimensions in order to learn, whereas intentional control can be recruited through task demands. Therefore showing that control can be recruited as a function of experimental instructions alone, that is, adapting the processing according to the instructions before the exposure to the task, can be taken as evidence for existence of control recruitment in the absence of learning. This was done by manipulating the information given at the outset of the experiment. In the first experiment, we manipulated list-level congruency proportion. Half of the participants were informed that most of the stimuli would be congruent, whereas the other half were informed that most of the stimuli would be incongruent. This held true for the stimuli in the second part of each experiment. In the first part, however, the proportion of the two stimulus types was equal. A proportion congruent effect was found in both parts of the experiment, but it was larger in the second part. In our second experiment, we manipulated the proportion of the stimuli within participants by applying an item-specific design. This was done by presenting some color words most often in their congruent color, and other color words in incongruent colors. Participants were informed about the exact word-color pairings in advance. Similar to Experiment 1, this held true only for the second experimental part. In contrast to our first experiment, informing participants in advance did not result in an item-specific proportion effect, which was observed only in the second part. Thus our results support the hypothesis that instructions may be enough to trigger list-level control, yet learning does contribute to the proportion congruent effect under such conditions. The item-level proportion effect is apparently caused by learning or at least it is moderated by it.

5. Reassessing manual proportions in Australopithecus afarensis.

Science.gov (United States)

2013-11-01

Previous analyses of hand morphology in Australopithecus afarensis have concluded that this taxon had modern human-like manual proportions, with relatively long thumbs and short fingers. These conclusions are based on the A.L.333 composite fossil assemblage from Hadar, Ethiopia, and are premised on the ability to assign phalanges to a single individual, and to the correct side and digit. Neither assignment is secure, however, given the taphonomy and sample composition at A.L.333. We use a resampling approach that includes the entire assemblage of complete hand elements at Hadar, and takes into account uncertainties in identifying phalanges by individual, side and digit number. This approach provides the most conservative estimates of manual proportions in Au. afarensis. We resampled hand long bone lengths in Au. afarensis and extant hominoids, and obtained confidence limits for distributions of manual proportions in the latter. Results confirm that intrinsic manual proportions in Au. afarensis are dissimilar to Pan and Pongo. However, manual proportions in Au. afarensis often fall at the upper end of the distribution in Gorilla, and very lower end in Homo, corresponding to disproportionately short thumbs and long medial digits in Homo. This suggests that manual proportions in Au. afarensis, particularly metacarpal proportions, were not as derived towards Homo as previously described, but rather are intermediate between gorillas and humans. Functionally, these results suggest Au. afarensis could not produce precision grips with the same efficiency as modern humans, which may in part account for the absence of lithic technology in this fossil taxon. PMID:24104947

6. Root-mean-square pulse-amplitude-to-number converters

International Nuclear Information System (INIS)

The amplitude dispersion of pulses from gas-discharge and other detectors of ionizing radiation is determined by the sum of the analog additive noise and is proportional to the amplitude of the Poisson component. Losses of energy resolution or overexpenditure of channels are reduced by conversion of pulse amplitude to code by comparison of the peak value with a periodic parabolic voltage. The described converter has a scale that is linear with respect to atomic number and provides a constancy peak width that is acceptable for a digital spectrum filter with constant parameters. With 256 channels, the dead time is less than or equal to 25.6 microseconds and the error of the root-mean-square scale is less than 0.1% of the instantaneous value. The described converter has undergone prolonged testing under laboratory and field conditions in conjunction with an AMA-8 portable x-ray spectrometer and has shown sufficiently high metrological characteristics

7. Remarks on Coulomb effects in multiple scattering theories

International Nuclear Information System (INIS)

We investigate the problem of introducing the Coulomb potential in Watson's multiple scattering expansion: in particular we formally analyse the implications for the optical potential and discuss various approximations necessary in order to make practical calculations

8. Fano effect through parallel-coupled double Coulomb islands

International Nuclear Information System (INIS)

By means of the nonequilibrium Green function and equation of motion method, the electronic transport is theoretically studied through a parallel-coupled double quantum dot (DQD) in the presence of on-dot Coulomb interaction U. With focus on the quantum interference in the U-dominant parallel-coupled DQD, we find two types of Fano interferences in the conductance spectra. If the one-particle DQD bonding and antibonding bands are well separated from their Coulomb blockade counterparts, the main features of Fano interference in usual DQD systems are recovered with minor revisions. The most interesting is the hybridization between the antibonding state and the Coulomb counterpart of the bonding state, which gives rises to two new channels for Fano resonance. The Fano interference in the Coulomb hybridized systems can be controlled by the electrostatic and magnetic approaches, and exhibits properties quite different from what are reported in the noninteracting Fano-Anderson model

9. Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures

Science.gov (United States)

Kaasbjerg, Kristen; Jauho, Antti-Pekka

2016-05-01

We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs)—a bias-driven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach that accounts for higher-order tunneling (cotunneling) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters. Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments on Coulomb drag in CQD systems.

10. Progress in studying scintillator proportionality: Phenomenological model

Energy Technology Data Exchange (ETDEWEB)

Bizarri, Gregory; Cherepy, Nerine; Choong, Woon-Seng; Hull, Giulia; Moses, William; Payne, Sephen; Singh, Jai; Valentine, John; Vasilev, Andrey; Williams, Richard

2009-04-30

We present a model to describe the origin of non-proportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non-linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation non-proportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.