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1

NSDL National Science Digital Library

Plot of the Yukawa potential showing the hard=core formulation of the Yukawa Potential for several combinations of Îµ and Îº. The Yukawa pair potential is used to model the interaction between charge stabilized colloids. It is a purely repulsive potential when considered two particles with like charge; oppositely charged particles will exhibit an attraction.

Iacovella, Christopher R.

2007-05-09

2

NASA Astrophysics Data System (ADS)

Relativistic symmetries of the Dirac equation under spin and pseudo-spin symmetries are investigated and a combination of Deng—Fan and Eckart potentials with Coulomb-like and Yukawa-like tensor interaction terms are considered. The energy equation is obtained by using the Nikiforov—Uvarov method and the corresponding wave functions are expressed in terms of the hypergeometric functions. The effects of the Coulomb and Yukawa tensor interactions are numerically discussed as well.

Akpan, N. Ikot; Zarrinkamar, S.; H. Yazarloo, B.; Hassanabadi, H.

2014-10-01

3

Bound eigenstates for the superposition of the Coulomb and the Yukawa potentials

NASA Astrophysics Data System (ADS)

The eigenvalue problem for two particles interacting through the potential being the superposition of the attractive Coulomb potential (-A/r) and the Yukawa potential B exp(-Cr)/r of arbitrary strength B and screening parameter C is solved by variational means. The energy levels Enl for the states 1s through 7i are calculated as functions of B and C. It is shown that for a given principal quantum number n the energy eigenvalues increase (decrease) with increasing azimuthal quantum number l if the Yukawa potential is attractive (repulsive), i.e., for l>l': Enl>=Enl' if B<0, and Enl<=Enl' if B>0. It leads to the crossing of the energy levels with n>=2. For B>0 the levels with larger n and l become lower than those with smaller n and l, e.g., E3d

Adamowski, Janusz

1985-01-01

4

Bound states of screened coulomb potentials

NASA Astrophysics Data System (ADS)

We propose an extension of the Ecker-Weizel approximation to treat the non-zero angular momentum bound states of a class of screened Coulomb potentials. As an illustration of our prescription, we have calculated the discrete energies Enl of the Yukawa potential, which are in excellent agreement with those of Rogers et al.

Dutt, Ranabir; Ray, Aparna; Ray, Pritam P.

1981-05-01

5

Envelope representations for screened Coulomb potentials

NASA Astrophysics Data System (ADS)

We study the discrete eigenvalues Enl of the Schrödinger Hamiltonian H=-(1/2)?+V(r), where V(r)=g(-1/r) is an increasing concave transformation of the Coulomb potential, and n is the principal (radial) quantum number. It is demonstrated by the method of potential envelopes that upper bounds are provided by the simple formula Enl<= mins>0 \\{(1/2)s+V((n+l)/s1/2)\\}, where s is a real variable. Numerical results are compared with previous work for two specific screened Coulomb potentials. In the case of the Yukawa potential V(r)=-(v/r)exp(-?r), it is shown that the inequality (n+l)2?/v<2/e is sufficient to guarantee the existence of the eigenvalue Enl: In the case of S states, sharp upper and lower bounds are also provided by a different method.

Hall, Richard L.

1985-07-01

6

OBSERVATIONAL EVIDENCE FOR DARK MATTER INTERACTING THROUGH A YUKAWA POTENTIAL

Recent observations in galaxies and clusters indicate that dark matter density profiles exhibit core-like structures which contradict the numerical simulation results of collisionless cold dark matter (CDM). On the other hand, it has been shown that CDM particles interacting through a Yukawa potential could naturally explain the cores in dwarf galaxies. In this Letter, I use the Yukawa potential interacting dark matter model to derive two simple scaling relations on the galactic and cluster scales, respectively, which give excellent agreements with observations. Also, in our model, the masses of the force carrier and dark matter particle can be constrained by the observational data.

Chan, M. H., E-mail: mhchan@phy.cuhk.edu.hk [Department of Physics and Institute of Theoretical Physics, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (Hong Kong)

2013-05-20

7

The generalized pseudospectral approach to the bound states of Hulthen and Yukawa potentials

The generalized pseudospectral method is employed to calculate the bound states of Hulth\\'en and Yukawa potentials in quantum mechanics, with special emphases on higher excited states and stronger couplings. Accurate energy eigenvalues, expectation values and radial probability densities are obtained through a nonuniform and optimal spatial discretization of the radial Schr\\"odinger equation. Results accurate up to thirteen to fourteen significant figures are reported for all the 55 eigenstates of both these potentials with $n\\leq$10 for arbitrary values of the screening parameters covering a wide range of interaction. Furthermore, excited states as high as up to $n=17$ have been computed with good accuracy for both these potentials. Excellent agreement with the available literature data has been observed in all cases. The $n>6$ states of Yukawa potential has been considerably improved over all other existing results currently available, while the same for Hulth\\'en potential are reported here for the first time. Excepting the $1s$ and $2s$ states of Yukawa potential, the present method surpasses in accuracy all other existing results in the stronger coupling region for all other states of both these systems. This offers a simple and efficient scheme for the accurate calculation of these and other screened Coulomb potentials.

Amlan K. Roy

2013-12-20

8

Three-dimensional stereoscopy of Yukawa (Coulomb) balls in dusty plasmas

A stereoscopic approach with standard video cameras for positioning and tracking of micrometer sized polymer particles in a radio-frequency gas discharge is presented. The stereoscopy is applied to simultaneously determine the positions of all particles in a three-dimensional strongly coupled spherical dusty plasma (Yukawa ball). The accuracy of the stereoscopic method is discussed. The shell structure and the occupation number of various Yukawa balls are determined and compared to recent simulations and models.

Kaeding, Sebastian; Melzer, Andre [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, 17489 Greifswald (Germany)

2006-09-15

9

Stationary solution of NLFP with coulombic potential

In a previous paper, Grassi (2012) [39], a new entropy form has been proposed for which it is possible to obtain a stationary solution of the Non-Linear Fokker-Planck equation (referred as NLFP) with coulombic-like potentials. In this paper we analyze the stationary solution of NLFP obtained by using pure coulombic potentials and we will use this solution to study an 'atomic-like' system. - Highlights: Black-Right-Pointing-Pointer The entropy introduced in a previous work has been studied for a coulombic potential. Black-Right-Pointing-Pointer From this entropy form a NLFP has been derived for a pure coulombic potential. Black-Right-Pointing-Pointer The stationary solution of the NLFP for an 'atomic-like' system has been obtained. Black-Right-Pointing-Pointer A comparison with Boltzmann entropy has been proposed.

Grassi, A., E-mail: agrassi@unict.it

2013-02-15

10

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

ERIC Educational Resources Information Center

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)

Francisco, E.; And Others

1988-01-01

11

In this paper, the Schr\\"odinger equation for 6-body system is studied. We solved this equation for lithium nucleus by using supersymmetry method with the specific potentials. These potentials are Yukawa potential, the generalized Yukawa potential and Hellmann potential. The results of our model for all calculations show that the ground state binding energy of Lithium nucleus with these potentials are very close to the ones obtained in experiments.

Ghazvini, M; Rajabi, A A

2014-01-01

12

QUANTUM PAINLEV II SOLUTION AND APPROXIMATED ANALYTIC SOLUTION OF THE YUKAWA POTENTIAL

QUANTUM PAINLEVÃ? II SOLUTION AND APPROXIMATED ANALYTIC SOLUTION OF THE YUKAWA POTENTIAL IRFAN of potential reduces to the quantum PainlevÃ© II equation and the solution of its Riccati form appears as a dominant term of that potential. Further, we show that PainlevÃ© II Riccati solution is an equivalent

Paris-Sud XI, UniversitÃ© de

13

Analytic superpotential for Yukawa potential by perturbation of the Riccati equation

The basic ingredient of supersymmetry is the analytic superpotential, which demands analytic ground state wave function, which does not exist for an arbitrary potential. We present a nice perturbative solution of the Riccati equation leading to an analytic superpotential for any arbitrary potential. Application to Yukawa potential gives excellent results.

Barnali Chakrabarti; Tapan Kumar Das

2001-01-01

14

TESTING YUKAWA-LIKE POTENTIALS FROM f(R)-GRAVITY IN ELLIPTICAL GALAXIES

We present the first analysis of extended stellar kinematics of elliptical galaxies where a Yukawa-like correction to the Newtonian gravitational potential derived from f(R)-gravity is considered as an alternative to dark matter. In this framework, we model long-slit data and planetary nebula data out to 7 R{sub eff} of three galaxies with either decreasing or flat dispersion profiles. We use the corrected Newtonian potential in a dispersion-kurtosis Jeans analysis to account for the mass-anisotropy degeneracy. We find that these modified potentials are able to fit nicely all three elliptical galaxies and the anisotropy distribution is consistent with that estimated if a dark halo is considered. The parameter which measures the 'strength' of the Yukawa-like correction is, on average, smaller than the one found previously in spiral galaxies and correlates both with the scale length of the Yukawa-like term and the orbital anisotropy.

Napolitano, N. R. [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello, 16, 80131-Napoli (Italy); Capozziello, S.; Capaccioli, M. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Napoli (Italy); Romanowsky, A. J. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Tortora, C., E-mail: napolita@na.astro.it [Institut fuer Theoretische Physik, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057, Zuerich (Switzerland)

2012-04-01

15

Bound eigenstates for two truncated Coulomb potentials

NASA Astrophysics Data System (ADS)

The eigenvalue problem for two particles interacting through the attractive truncated Coulomb potential, V(r)=-Ze2/(rp+?p)1/p, for p=1 and 2 is solved numerically. Energy eigenvalues accurate to within eight to six significant figures for the states 1s to 4f are calculated as a function of the truncation parameter ?. It is found that the level ordering satisfies Enl>Enl' for l

Singh, David; Varshni, Y. P.; Dutt, Ranabir

1985-07-01

16

Potential energy landscapes of Th isotopes within the Lublin Strasbourg drop + Yukawa-folded model

with the Lublin Strasbourg drop (LSD) model [1] and the Yukawa-folded (YF) mean field potential [2 and the corrections due to the shell and pairing effects for protons and neutrons: Etot = ELSD + Eshell + Epair. (1) The LSD model [1] was used to evaluate the macroscopic part of the energy. The shell corrections

Pomorski, Krzysztof

17

Analytical computation of amplification of coupling in relativistic equations with Yukawa potential

The approximate analytic solutions to the Klein-Gordon and Dirac equations with the Yukawa potential were derived by using the quasilinearization method (QLM). The accurate analytic expressions for the ground state energies and wave functions were presented. These high-precision approximate analytic representations are obtained by first casting the proper relativistic equation into a nonlinear Riccati form and then solving that nonlinear

E. Z. Liverts; V. B. Mandelzweig

2009-01-01

18

Analytical computation of amplification of coupling in relativistic equations with Yukawa potential

The approximate analytic solutions to the Klein–Gordon and Dirac equations with the Yukawa potential were derived by using the quasilinearization method (QLM). The accurate analytic expressions for the ground state energies and wave functions were presented. These high-precision approximate analytic representations are obtained by first casting the proper relativistic equation into a nonlinear Riccati form and then solving that nonlinear

E. Z. Liverts; V. B. Mandelzweig

2009-01-01

19

Quantum Painlevé II solution and Approximated analytic solution of the Yukawa Potential

We show that one dimensional non-stationary Schr\\"odi-nger equation with a specific choice of potential reduces to the quantum Painlev\\'e II equation and the solution of its Riccati form appears as a dominant term of that potential. Further, we show that Painlev\\'e II Riccati solution is an equivalent representation of centrifugal expression of radial Schr\\"odinger potential. This expression is used to derive the approximated form of the Yukawa potential of radial Schr\\"odinger equation which can be solved by applying the Nikiforov-Uvarov method. Finally, we express the approximated form of Yukawa potential explicitly in terms of qunatume Painlev\\'e II solution.

Irfan Mahmood

2014-03-27

20

Quantum gravity and the Coulomb potential

We apply a singularity-resolution technique utilized in loop quantum gravity to the polymer representation of quantum mechanics on R with the singular -1/|x| potential. On an equispaced lattice, the resulting eigenvalue problem is identical to a finite-difference approximation of the Schroedinger equation. We find numerically that the antisymmetric sector has an energy spectrum that converges to the usual Coulomb spectrum as the lattice spacing is reduced. For the symmetric sector, in contrast, the effect of the lattice spacing is similar to that of a continuum self-adjointness boundary condition at x=0, and its effect on the ground state is significant even if the spacing is much below the Bohr radius. Boundary conditions at the singularity thus have a significant effect on the polymer quantization spectrum even after the singularity has been regularized.

Husain, Viqar; Winkler, Oliver [Department of Mathematics and Statistics, University of New Brunswick, Fredericton, NB E3B 5A3 (Canada); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, N2L 2Y5 ON (Canada); Louko, Jorma [School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2007-10-15

21

An Analysis of 178Pb to 238U Isotopes with the Universal and Yukawa Proximity Potentials

NASA Astrophysics Data System (ADS)

The alpha particle preformation and the penetration probability by the Yukawa proximity potential in the even-even nuclei from 178Pb to 238U are studied. Using the experimental values of the alpha decay half-lives and the decay energies, we extract the preformation factors and the penetration probabilities. We also calculate the assault frequencies and the decay constants. The obtained results are motivating.

Javadimanesh, E.; Hassanabadi, H.; Zarrinkamar, S.

2013-07-01

22

We have carried out calculations of multipole polarizabilities of helium and the hydrogen negative ion interacting with pure Coulomb and screened Coulomb potentials using highly accurate correlated exponential wave functions with exponent generated by a quasirandom process. The dipole, quadrupole, and octupole polarizabilities for the ground 1s{sup 2} {sup 1}S{sup e} state for different screening parameters starting from infinity (pure Coulomb case) to small values of the screening parameters, are reported. The octupole polarizability of the hydrogen negative ion is reported for the first time in the literature. The bound 4 {sup 1}F state energy of helium for different screening parameters are also reported.

Kar, Sabyasachi [Center for Theoretical Atomic and Molecular Physics, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); Ho, Y. K. [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106 (China)

2009-12-15

23

Yukawa-type potential effects in the anomalistic period of celestial bodies

NASA Astrophysics Data System (ADS)

Several contemporary modified models of gravity predict the existence of a non-Newtonian Yukawa-type correction to the classical gravitational potential. We study the motion of a secondary celestial body under the influence of the corrected gravitational force of a primary. We derive two equations to approximate the periastron time rate of change and its total variation over one revolution (i.e., the difference between the anomalistic period and the Keplerian period) under the influence of the non-Newtonian radial acceleration. Kinematically, this influence produces apsidal motion. We performed numerical estimations for Mercury, for the companion star of the pulsar PSR 1913+16, and for the extrasolar Planet b of the star HD 80606. We also considered the case of the artificial Earth satellite GRACE-A, but the results present a low degree of reliability from a practical standpoint.

Haranas, Ioannis; Ragos, Omiros; Mioc, Vasile

2011-03-01

24

Spectral sum for the color-Coulomb potential in SU(3) Coulomb gauge lattice Yang-Mills theory

We discuss the essential role of the low-lying eigenmodes of the Faddeev-Popov (FP) ghost operator on the confining color-Coulomb potential using SU(3) quenched lattice simulations in the Coulomb gauge. The color-Coulomb potential is expressed as a spectral sum of the FP ghost operator and has been explored by partially summing the FP eigenmodes. We take into account the Gribov copy effects that have a great impact on the FP eigenvalues and the color-Coulomb potential. We observe that the lowest eigenvalue vanishes in the thermodynamic limit much faster than that in the Landau gauge. The color-Coulomb potential at large distances is governed by the near-zero FP eigenmodes; in particular, the lowest one accounts for a substantial portion of the color-Coulomb string tension comparable to the Wilson string tension.

Nakagawa, Y.; Nakamura, A. [Research Institute for Information Science and Education, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8521 (Japan); Saito, T. [Integrated Information Center, Kochi University, Kochi, 780-8520 (Japan); Toki, H. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka, 567-0047 (Japan)

2010-03-01

25

Analytical computation of amplification of coupling in relativistic equations with Yukawa potential

The approximate analytic solutions to the Klein-Gordon and Dirac equations with the Yukawa potential were derived by using the quasilinearization method (QLM). The accurate analytic expressions for the ground state energies and wave functions were presented. These high-precision approximate analytic representations are obtained by first casting the proper relativistic equation into a nonlinear Riccati form and then solving that nonlinear equation in the first QLM iteration. The choice of zero iteration is based on general features of the exact solutions near the origin and infinity. To estimate the accuracy of the QLM solutions, the exact numerical solutions were found, as well. The analytical QLM solutions are found to be extremely accurate for a small exponent parameter w of the Yukawa potential. The reasonable accuracy is kept for the medium values of w. When w approaches the critical values, the precision of the QLM results falls down markedly. However, the approximate analytic QLM solution to the Dirac equation corresponding to the maximum relativistic effect turned out to be very accurate even for w close to the exact critical w{sub ex}{sup Dir}=1.6767, whereas the QLM calculations yield w{sub qlm}{sup Dir}=1.6763. This effect of 'amplification' in compare with the Schroedinger equation critical parameter w{sub ex}{sup Sch}=1.1906 was investigated earlier [S. De Leo, P. Rotelli, Phys. Rev. D 69 (2004) 034006]. In this work, it was found that the 'amplification' for the Klein-Gordon equation became all the more evident. The exact numerical value is w{sub ex}{sup KG}{approx_equal}2.25, whereas the QLM approximation yields w{sub qlm}{sup KG}{approx_equal}2.15.

Liverts, E.Z. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)], E-mail: liverts@phys.huji.ac.il; Mandelzweig, V.B. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

2009-02-15

26

We consider a classical system of two-dimensional (2D) charged particles, interacting through a repulsive Yukawa potential exp(-r\\/lambda)\\/r, and confined in a parabolic channel that limits the motion of the particles in the y direction. Along the x direction, the particles are subject to a periodic potential. The ground-state configurations and the normal-mode spectra of the system are obtained as a

J. C. N. Carvalho; W. P. Ferreira; G. A. Farias; F. M. Peeters

2011-01-01

27

Spectra generated by a confined softcore Coulomb potential

NASA Astrophysics Data System (ADS)

Analytic and approximate solutions for the energy eigenvalues generated by a confined softcore Coulomb potentials of the form a/(r + ?) in d > 1 dimensions are constructed. The confinement is effected by linear and harmonic-oscillator potential terms, and also through "hard confinement" by means of an impenetrable spherical box. A byproduct of this work is the construction of polynomial solutions for a number of linear differential equations with polynomial coefficients, along with the necessary and sufficient conditions for the existence of such solutions. Very accurate approximate solutions for the general problem with arbitrary potential parameters are found by use of the asymptotic iteration method.

Hall, Richard L.; Saad, Nasser

2014-08-01

28

Macroscopic Screening of Coulomb Potentials From UV/IR-Mixing

We compute the static potential in a non-commutative theory including a term due to UV/IR-mixing. As a result, the potential decays exponentially fast with distance rather than like a power law Coulomb type potential due to the exchange of massless particles. This shows that when quantum effects are taken into account the introduction of non-commutativity not only modifies physics at short distances but has dramatic macroscopic consequences as well. As a result, we give a lower bound on the scale of non-commutativity (if present at all) to be compatible with observations.

Robert C. Helling; Jiangyang You

2007-07-12

29

Self-diffusion in strongly coupled Yukawa systems (complex plasmas)

NASA Astrophysics Data System (ADS)

We show that the idea of mapping between the Newtonian and Brownian diffusivities proposed and tested on a class of particle systems interacting via soft and ultra-soft potentials (inverse-power-law, Gaussian core, Hertzian, and effective star-polymer) by Pond et al. [Soft Matter 7, 9859 (2011)] is also applicable to the Yukawa (screened Coulomb) interaction. Some consequences of this result with respect to self-diffusion in strongly coupled complex (dusty) plasmas are discussed.

Khrapak, Sergey A.; Vaulina, Olga S.; Morfill, Gregor E.

2012-03-01

30

Heavy quarks, gluons and the confinement potential in Coulomb gauge

We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.

Popovici, Carina; Watson, Peter; Reinhardt, Hugo [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2011-05-23

31

We consider a classical system of two-dimensional (2D) charged particles,\\u000awhich interact through a repulsive Yukawa potential $exp(-r\\/\\\\lambda)\\/r$,\\u000aconfined in a parabolic channel which limits the motion of the particles in the\\u000a$y$-direction. Along the $x$-direction, the particles are also subject to a\\u000aperiodic potential substrate. The ground state configurations and the normal\\u000amode spectra of the system are obtained

J. C. N. Carvalho; W. P. Ferreira; G. A. Farias; F. M. Peeters

2010-01-01

32

Screened Coulomb potentials for astrophysical nuclear fusion reactions

The electron-screening acceleration of laboratory fusion reactions at astrophysical energies is an unsolved problem of great importance to astrophysics. That effect is modeled here by considering the fusion of hydrogen-like atoms whose electron probability density is used in Poisson's equation in order to derive the corresponding screened Coulomb potential energy. That way atomic excitations and deformations of the fusing atoms can be taken into account. Those potentials are then treated semiclassically in order to obtain the screening (accelerating) factor of the reaction. By means of the proposed model the effect of a superstrong magnetic field on laboratory Hydrogen fusion reactions is investigated here for the first time showing that, despite the considerable increase in the cross section of the $% dd$ reaction, the $pp$ reaction is still too slow to justify experimentation. The proposed model is finally applied on the $H^{2}(d,p) H^{3}$ fusion reaction describing satisfactorily the experimental data although some ambiguity remains regarding the molecular nature of the deuteron target. Notably, the present method gives a sufficiently high screening energy for Hydrogen fusion reactions so that the take-away energy of the spectator nucleus can also be taken into account.

Theodore E. Liolios

2000-05-05

33

NASA Astrophysics Data System (ADS)

We present a detailed derivation of the renormalization group equations for two-dimensional electromagnetic Coulomb gases whose charges lie on a triangular lattice (magnetic charges) and its dual (electric charges). The interactions between the charges involve both angular couplings and a new electromagnetic potential. This motivates the denomination of "elastic" Coulomb gas. Such elastic Coulomb gases arise naturally in the study of the continuous melting transition of two-dimensional solids coupled to a substrate, either commensurate or with quenched disorder.

Carpentier, David; Le Doussal, Pierre

2008-06-01

34

Effective-Mass Klein-Gordon-Yukawa Problem for Bound and Scattering States

Bound and scattering state solutions of the effective-mass Klein-Gordon equation are obtained for the Yukawa potential with any angular momentum $\\ell$. Energy eigenvalues, normalized wave functions and scattering phase shifts are calculated as well as for the constant mass case. Bound state solutions of the Coulomb potential are also studied as a limiting case. Analytical and numerical results are compared with the ones obtained before.

Altug Arda; Ramazan Sever

2011-08-22

35

NASA Astrophysics Data System (ADS)

We consider a classical system of two-dimensional (2D) charged particles, interacting through a repulsive Yukawa potential exp(-r/?)/r, and confined in a parabolic channel that limits the motion of the particles in the y direction. Along the x direction, the particles are subject to a periodic potential. The ground-state configurations and the normal-mode spectra of the system are obtained as a function of the periodicity and strength of the periodic potential (V0) and density. An interesting set of tunable ground-state configurations are found, with first- or second-order structural transitions between them. A configuration with particles aligned, perpendicular to the x direction, in each minimum of the periodic potential is obtained for V0 larger than some critical value that has a power-law dependence on the density. The phonon spectrum of different configurations was also calculated. A localization of the modes into a small frequency interval is observed for sufficiently large strength of the periodic potential, and a tunable gap in the phonon spectrum is found as a function of V0.

Carvalho, J. C. N.; Ferreira, W. P.; Farias, G. A.; Peeters, F. M.

2011-03-01

36

We consider a classical system of two-dimensional (2D) charged particles, which interact through a repulsive Yukawa potential $exp(-r/\\lambda)/r$, confined in a parabolic channel which limits the motion of the particles in the $y$-direction. Along the $x$-direction, the particles are also subject to a periodic potential substrate. The ground state configurations and the normal mode spectra of the system are obtained as function of the periodicity and strength of the periodic potential ($V_0$), and density. An interesting set of tunable ground state configurations are found, with first and second order structural transitions between them. A magic configuration with particles aligned in each minimum of the periodic potential is obtained for V_0 larger than some critical value which has a power law dependence on the density. The phonon spectrum of different configurations were also calculated. A localization of the modes into a small frequency interval is observed for a sufficient strength of the periodic potential. A tunable band-gap is found as a function of $V_0$. This model system can be viewed as a generalization of the Frenkel and Kontorova model.

J. C. N. Carvalho; W. P. Ferreira; G. A. Farias; F. M. Peeters

2010-06-10

37

NASA Astrophysics Data System (ADS)

The liquid-vapor phase diagrams of equal size diameter ? binary mixtures of screened potentials have been reported for several ranges of interaction using Monte Carlo simulation methods [J. B. Caballero, A. M. Puertas, A. Fer?andez-Barbero, F. J. de las Nieves, J. M. Romero-Enrique, and L. F. Rull, J. Chem. Phys. 124, 054909 (2006); A. Fortini, A.-P. Hynninen, and M. Dijkstra, J. Chem. Phys. 125, 094502 (2006)]. Both works report controversial results about the stability of the phase diagram with the inverse Debye screening length ?. Caballero found stability for values of ?? up to 20 while Fortini reported stability for ?? up to 20 while Fortini reported stability for ?? <= 4. In this work a spinodal decomposition process where the liquid and vapor phases coexist through an interface in a slab geometry is used to obtain the phase equilibrium and surface properties using a discontinuous molecular dynamics simulations for mixtures of equal size particles carrying opposite charge and interacting with a mixture of attractive and repulsive Yukawa potentials at different values of ??. An crude estimation of the triple point temperatures is also reported. The isothermal-isobaric method was also used to determine the phase stability using one phase simulations. We found that liquid-vapor coexistence is stable for values of ?? > 20 and that the critical temperatures have a maximum value at around ?? = 10, in agreement with Caballero et al. calculations. There also exists a controversy about the liquid-vapor envelope stability of the pure component attractive Yukawa model which is also discussed in the text. In addition, details about the equivalence between continuous and discontinuous molecular dynamics simulations are given, in the Appendix, for Yukawa and Lennard-Jones potentials.

Chapela, Gustavo A.; del Río, Fernando; Alejandre, José

2013-02-01

38

The algebra of the quantum nondegenerate three-dimensional Kepler-Coulomb potential

The classical generalized Kepler-Coulomb potential, introduced by Verrier and Evans, corresponds to a quantum superintegrable system, with quadratic and quartic integrals of motion. In this paper we show that the algebra of the integrals is a quadratic ternary algebra, i.e a quadratic extension of a Lie triple system.

Tanoudis, Y.; Daskaloyannis, C., E-mail: daskalo@math.auth.gr [Aristotle University of Thessaloniki, Mathematics Department (Greece)

2011-07-15

39

Physica E 40 (2008) 12701272 Potential dependent intra-dot Coulomb interaction in quantum dots

, by attaching ligand fields. Such modification of potential alters not only the single-electron energy spectrum but also mutual Coulomb interaction. The latter results in compli- cated movements of many-body energy and the response to magnetic field. 2. Experiment Fig. 1(a) is a scanning electron microscope (SEM) image of our

Iye, Yasuhiro

40

Simple eigenvalue formula for the Coulomb-plus-linear potential

NASA Astrophysics Data System (ADS)

The eigenvalues Enl(?) of the Hamiltonian H=-?-1r+?r are analyzed with the help of potential envelopes and kinetic potentials. The result is the following simple approximate eigenvalue formula: ?={2(?E)3-?E2[(1+3?2E)12-1]}?[(1+3?2E)12-1]3, where E>=-14?2 is a lower bound to Enl(?) if ?=?=(n+l), an upper bound if ?=?=(2n+l-12), and a good approximation when ?=(n+l) and ?=(1.794n+l-0.418).

Hall, Richard L.

1984-07-01

41

Quantum Monte Carlo method for attractive Coulomb potentials

Starting from an exact lower bound on the imaginary-time propagator, we\\u000apresent a Path-Integral Quantum Monte Carlo method that can handle singular\\u000aattractive potentials. We illustrate the basic ideas of this Quantum Monte\\u000aCarlo algorithm by simulating the ground state of hydrogen and helium.

J. S. Kole; H. De Raedt

2001-01-01

42

Quantum Monte Carlo method for attractive Coulomb potentials

Starting from an exact lower bound on the imaginary-time propagator, we present a path-integral quantum Monte Carlo method that can handle singular attractive potentials. We illustrate the basic ideas of this quantum Monte Carlo algorithm by simulating the ground state of hydrogen and helium.

J. S. Kole; H. de Raedt

2001-01-01

43

Dependence of Coulomb Sum Rule on the Short Range Correlation by Using Av18 Potential

NASA Astrophysics Data System (ADS)

The Coulomb sum rule (CSR) and structure factor are calculated for inelastic electron scattering from nuclear matter at zero and finite temperature in the nonrelativistic limit. The effect of short-range correlation (SRC) is presented by using lowest order constrained variational (LOCV) method and the Argonne Av18 and ?-Reid soft-core potentials. The effects of different potentials as well as temperature are investigated. It is found that the nonrelativistic version of Bjorken scaling approximately sets in at the momentum transfer of about 1.1 to 1.2 GeV/c and the increase of temperature makes it to decrease. While different potentials do not significantly change CSR, the SRC improves the Coulomb sum rule and we get reasonably close results to both experimental data and others theoretical predictions.

Modarres, M.; Moeini, H.; Moshfegh, H. R.

44

Self Diffusion of Yukawa system in presence of external magnetic field

Diffusion of dust particles is one of the most significant transport processes of strongly coupled dusty plasma that reflect the nature of inter particle interaction and characterize thermodynamics of the system. In this paper the effect of magnetic field on diffusion of dust particles in strongly coupled dusty plasma is investigated by using molecular dynamics simulations. Self- diffusion coefficients of Yukawa systems are obtained for a wide range of plasma parameters and magnetic field strength using Green- Kubo expression which is based on integrated velocity autocorrelation function (VACF). It is assumed that dust particles interact with each other by modified Yukawa (i.e. screened Coulomb) potential. The study gives interesting results of dust particle diffusion in magnetized plasma.

Begum, Mahmuda

2014-01-01

45

Close-coupling techniques often break down when transitions to a continuum or quasicontinuum cannot be neglected. This work describes an extension of a recently proposed method [L. F. Errea, L. Mendez, and A. Riera, Chem. Phys. Lett. 164, 261 (1989)] to deal with such situations, when the coupling terms involve Coulomb potentials. A connection with the method of packet states is made, and a preliminary application of the method is presented.

Dreizler, R.M. (Institut fuer Theoretische Physik der Universitaet Frankfurt, Robert Mayer Strasse 8, D-6000 Frankfurt (Germany)); Errea, L.F. (Departamento de Quimica, C-XIV, Universidad Autonoma de Madrid, Canto Blanco, 28049-Madrid (Spain)); Henne, A.; Luedde, H.J. (Institut fuer Theoretische Physik der Universitaet Frankfurt, Robert Mayer Strasse 8, D-6000 Frankfurt (Germany)); Riera, A.; Sanchez, P. (Departamento de Quimica, C-XIV, Universidad Autonoma de Madrid, Canto Blanco, 28049-Madrid (Spain))

1993-05-01

46

Chiral symmetry breaking in the truncated Coulomb Gauge II. Non-confining power law potentials

In this paper we study the breaking of chiral symmetry with non-confining power-like potentials. The region of allowed exponents is identified and, after the previous study of confining (positive exponent) potentials, we now specialize in shorter range non-confining potentials, with a negative exponent. These non-confining potentials are close to the Coulomb potential, and they are also relevant as corrections to the linear confinement, and as models for the quark potential at the deconfinement transition. The mass-gap equation is constructed and solved, and the quarks mass, the chiral angle and the quark energy are calculated analytically with a exponent expansion in the neighbourhood of the Coulomb potential. It is demonstrated that chiral symmetry breaking occurs, but only the chiral invariant false vacuum and a second non-trivial vacuum exist. Moreover chiral symmetry breaking is led by the UV part of the potential, with no IR enhancement of the quark mass. Thus the breaking of chiral symmetry driven by non-confining potentials differs from the one lead by confining potentials.

P. Bicudo

2008-11-04

47

Chiral symmetry breaking in the truncated Coulomb Gauge II. Non-confining power law potentials

In this paper we study the breaking of chiral symmetry with non-confining power-like potentials. The region of allowed exponents is identified and, after the previous study of confining (positive exponent) potentials, we now specialize in shorter range non-confining potentials, with a negative exponent. These non-confining potentials are close to the Coulomb potential, and they are also relevant as corrections to the linear confinement, and as models for the quark potential at the deconfinement transition. The mass-gap equation is constructed and solved, and the quarks mass, the chiral angle and the quark energy are calculated analytically with a exponent expansion in the neighbourhood of the Coulomb potential. It is demonstrated that chiral symmetry breaking occurs, but only the chiral invariant false vacuum and a second non-trivial vacuum exist. Moreover chiral symmetry breaking is led by the UV part of the potential, with no IR enhancement of the quark mass. Thus the breaking of chiral symmetry driven by n...

Bicudo, P

2008-01-01

48

Treatment of the two-body Coulomb problem as a short-range potential

The scattering wave function and the transition amplitude for the two-body Coulomb problem are written as power series of the Sommerfeld parameter. Making use of a mathematical study of the nth derivatives of Kummer function with respect to its first parameter, the series coefficients are expressed analytically in terms of multivariable hypergeometric functions. We establish the connection with the Born series based on the free particle Green's function and show its applicability to long-range potentials. We also relate our analysis to recent works on the distorted-wave theory for the Coulomb problem. For the transition amplitude, the Born series is presented and compared to the series obtained from the exact well-known Rutherford result. Since the two series differ, care must be taken when extracting the relevant information about the scattering. Finally, implications for three-body problems are discussed.

Gasaneo, G. [Departamento de Fisica, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8000 Bahia Blanca, Buenos Aires (Argentina); Ancarani, L. U. [Laboratoire de Physique Moleculaire et des Collisions, Universite Paul Verlaine-Metz, 57078 Metz (France)

2009-12-15

49

Decrypting gauge-Yukawa cookbooks

NASA Astrophysics Data System (ADS)

For many years, theorists have calculated formulas for useful quantities in general gauge-Yukawa theories. However, these cookbooks are often very difficult to use since the general notation is far removed from practical model building. In this paper, we present the structure delta, which allows us to use a surprisingly convenient notation that bridges the gap between general gauge-Yukawa theories and specific models. This is particularly useful for the computation of beta functions, but can also be extended to handle spontaneous symmetry breaking, the effective potential and a variety of other quantities. We will introduce it using the standard model of particle physics and a toy model with an SU( N c ) gauge symmetry.

Mølgaard, Esben

2014-07-01

50

New look at the modified Coulomb potential in a strong magnetic field

NASA Astrophysics Data System (ADS)

The static Coulomb potential of quantum electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass mdyn, i.e., |q?2|?mdyn2?|eB| and mdyn2?|q?2|?|eB|, where q? is the longitudinal component of the momentum relative to the external magnetic field B. The result is then compared with the static potential arising from Born approximation. Both results coincide. Although the arising potentials show different behavior in the aforementioned regimes, a novel dependence on the angle ? between the particle-antiparticle’s axis and the direction of the magnetic field is observed. In the regime |q?2|?mdyn2?|eB|, for strong enough magnetic field and depending on the angle ?, a qualitative change occurs in the Coulomb-like potential; whereas for ?=0, ? the potential is repulsive, it exhibits a minimum for angles ??]0,?[.

Sadooghi, N.; Jalili, A. Sodeiri

2007-09-01

51

A new look at the modified Coulomb potential in a strong magnetic field

The static Coulomb potential of Quantum Electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level (LLL) approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass $m_{dyn.}$, {\\it i.e.}, $|{\\mathbf{q}}_{\\|}^{2}|\\ll m_{dyn.}^{2}\\ll |eB|$ and $m_{dyn.}^{2}\\ll |\\mathbf{q}_{\\|}^{2}|\\ll|eB|$, where $\\mathbf{q}_{\\|}$ is the longitudinal components of the momentum relative to the external magnetic field $B$. The result is then compared with the static potential arising from Born approximation. Both results coincide. Although the arising potentials show different behavior in the aforementioned regimes, a novel dependence on the angle $\\theta$ between the particle-antiparticle's axis and the direction of the magnetic field is observed. In the regime $|{\\mathbf{q}}_{\\|}^{2}|\\ll m_{dyn.}^{2}\\ll |eB|$, for strong enough magnetic field and depending on the angle $\\theta$, a qualitative change occurs in the Coulomb-like potential; Whereas for $\\theta=0,\\pi$ the potential is repulsive, it exhibits a minimum for angles $\\theta\\in]0,\\pi[$.

N. Sadooghi; A. Sodeiri Jalili

2007-05-30

52

NASA Astrophysics Data System (ADS)

Using eight different versions of the nuclear potential, we have calculated the height and position of the Coulomb barrier for reactions induced by loosely bound projectiles, 6Li, 7Li and 9Be. A total of 13 reactions have been studied and by comparing the results with the empirical values, we found the prediction of all the potentials quite satisfactory as they could reproduce the empirical values within 5% on average. The potentials Bass 80, BW 91 and AW 95 can determine the experimental barrier within 2% on average. For the reaction 6Li + 152Sm the deviations from the empirical values are unusually large. On applying the correction of the Coulomb potential for the deformed target 152Sm the new values obtained are found to be closer to the empirical values. Applying Wong's formula the fusion cross-sections for four reactions are compared with the results of single BPM. The fittings of the fusion cross-section for the potentials of CW 76, BW 91 and Bass 80 are better than the rest.

Phookan, C. K.; Kalita, K.

2013-02-01

53

General Pade Effective Potential for Coulomb Problems in Condensed and Soft Matters

NASA Astrophysics Data System (ADS)

Effective potentials for finding the ground states and physical configurations have essential meaning in many Coulomb problems of condensed and soft matters. The ordinary n-Pade approximation potentials define as the ratio of Pi(r)/Pi+1(r), where Pi(r) are the polynomials of i-th order of charge separation r, give quite good fit and agreement of calculation results and experimental data for Coulomb problems, where screening effects are not important or exchange photons still are massless. In this work we consider a general Pade effective potential by included a factor of exponential form, which could give more accurate results also for above mentioned cases. This general Pade effective potentials with analytical expressions were useful to perform analytical calculations, estimations and to reduce the amount of computational time for future investigations in condensed and soft matter topics. For example of soft matter problems, we study the case of MS2 virus, the general Pade potential gives much more correct results comparing with ordinary Pade approximation.

Quyen, B. L.; Mai, D. N.; Hoa, N. M.; Van, T. T. T.; Hoai, N. L.; Viet, N. A.

2014-09-01

54

A new look at the modified Coulomb potential in a strong magnetic field

The static Coulomb potential of Quantum Electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level (LLL) approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass m_{dyn.}, i.e., |{\\mathbf{q}}_{\\|}^2| magnetic field B. The result is then compared with the static potential arising from a Born approximation. Both results coincide. Although the arising potentials show different behavior in the aforementioned regimes, a novel dependence on the angle \\theta between the particle-antiparticle's axis and the direction of the magnetic field is observed. A qualitative analysis of these potentials shows that in the regime |{\\mathbf{q}}_{\\|}^2| << m_{dyn.}^2 <...

Sadooghi, N

2007-01-01

55

Effect of a relativistic correction to the Coulomb potential on the energy levels of hydrogen atom

Based on classical electrodynamics, it is argued that the Coulomb potential (which is strictly valid for two point charges at rest), commonly used in the study of energy levels of hydrogen atom is not the correct one, because the electron in the hydrogen atom moves with relativistic speeds with respect to the nucleus. Retardation effect has to be considered in accordance with Li\\'{e}nard-Wiechert (or retarded) potential of a moving charge or the relativistic electrodynamics. However, such a consideration introduces a correction to the Coulomb potential, whose quantum mechanical expectation value is estimated at $E_{ret} = - \\frac{mc^2\\alpha ^4}{2n^3(l+1/2)}$, which is of the same order as the fine structure of hydrogen atom and hence added to the standard energy eigenvalue values of H-atom. This correction lifts the $l$-degeneracy in the spectra of H-atom and hence modifies the standard result. The result disturbs the existing agreement between the theory and experiments on H-atom and hence requires further theoretical and experimental re-examination. The implications of this result for the Kepler-problem in general is also discussed in the context of Heaviside's gravity, which seems to offer an alternative explanation for the non-Newtonian perihelion advance of Mercury without invoking the space-time curvature formalism of Einstein's general theory of relativity.

Harihar Behera

2012-01-08

56

In the three-dimensional flat space, a classical Hamiltonian, which has five functionally independent integrals of motion, including the Hamiltonian, is characterized as superintegrable. Kalnins, Kress and Miller (J. Math. Phys. 48 (2007), 113518, 26 pages) have proved that, in the case of nondegenerate potentials, i.e. potentials depending linearly on four parameters, with quadratic symmetries, posses a sixth quadratic integral, which is linearly independent of the other integrals. The existence of this sixth integral imply that the integrals of motion form a ternary quadratic Poisson algebra with five generators. The superintegrability of the generalized Kepler-Coulomb potential that was investigated by Verrier and Evans (J. Math. Phys. 49 (2008), 022902, 8 pages) is a special case of superintegrable system, having two independent integrals of motion of fourth order among the remaining quadratic ones. The corresponding Poisson algebra of integrals is a quadratic one, having the same special form, characteristic to the nondegenerate case of systems with quadratic integrals. In this paper, the ternary quadratic associative algebra corresponding to the quantum Verrier-Evans system is discussed. The subalgebras structure, the Casimir operators and the the finite-dimensional representation of this algebra are studied and the energy eigenvalues of the nondegenerate Kepler-Coulomb are calculated.

Yannis Tanoudis; Costas Daskaloyannis

2011-02-02

57

Evidence of kaon nuclear and Coulomb potential effects on soft K+ production from nuclei

The ratio of forward K+ production on copper, silver and gold targets to that on carbon has been measured at proton beam energies between 1.5 and 2.3 GeV as a function of the kaon momentum p_K using the ANKE spectrometer at COSY-Juelich. The strong suppression in the ratios observed for p_K<200-250 MeV/c can be ascribed to a combination of Coulomb and nuclear repulsion in the K+A system. This opens a new way to investigate the interaction of K+-mesons in the nuclear medium. Our data are consistent with a K+A nuclear potential of V_K~20 MeV at low kaon momenta and normal nuclear density. Given the sensitivity of the data to the kaon potential, the current experimental precision might allow one to determine V_K to better than 3 MeV.

M. Nekipelov; M. Buescher; W. Cassing; M. Hartmann; V. Hejny; V. Kleber; H. R. Koch; V. Koptev; Y. Maeda; R. Maier; S. Merzliakov; S. Mikirtychiants; H. Ohm; A. Petrus; D. Prasuhn; F. Rathmann; Z. Rudy; R. Schleichert; H. Schneider; K. Sistemich; H. J. Stein; H. Stroeher; K. -H. Watzlawik; C. Wilkin

2002-02-26

58

Diffusivity in asymmetric Yukawa ionic mixtures in dense plasmas.

In this paper we present molecular dynamics (MD) calculations of the interdiffusion coefficient for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and inertial confinement fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density ?10(25) ions/cm(3). The motion of 30,000-120,000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction; the electrons are not simulated explicitly. The species diffusivity is then calculated using the Green-Kubo approach using an integral of the interdiffusion current autocorrelation function, a quantity calculated in the equilibrium MD simulations. Our MD simulation results show that a widely used expression relating the interdiffusion coefficient with the concentration-weighted sum of self-diffusion coefficients overestimates the interdiffusion coefficient. We argue that this effect due to cross-correlation terms in velocities is characteristic of asymmetric mixed plasmas. Comparison of the MD results with predictions of kinetic theories also shows a discrepancy with MD giving effectively a larger Coulomb logarithm. PMID:25215836

Haxhimali, Tomorr; Rudd, Robert E; Cabot, William H; Graziani, Frank R

2014-08-01

59

Diffusivity in asymmetric Yukawa ionic mixtures in dense plasmas

NASA Astrophysics Data System (ADS)

In this paper we present molecular dynamics (MD) calculations of the interdiffusion coefficient for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and inertial confinement fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density ˜1025 ions/cm3. The motion of 30 000-120 000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction; the electrons are not simulated explicitly. The species diffusivity is then calculated using the Green-Kubo approach using an integral of the interdiffusion current autocorrelation function, a quantity calculated in the equilibrium MD simulations. Our MD simulation results show that a widely used expression relating the interdiffusion coefficient with the concentration-weighted sum of self-diffusion coefficients overestimates the interdiffusion coefficient. We argue that this effect due to cross-correlation terms in velocities is characteristic of asymmetric mixed plasmas. Comparison of the MD results with predictions of kinetic theories also shows a discrepancy with MD giving effectively a larger Coulomb logarithm.

Haxhimali, Tomorr; Rudd, Robert E.; Cabot, William H.; Graziani, Frank R.

2014-08-01

60

Coulomb explosion potential sputtering induced by slow highly charged ion impact

We have observed secondary ion emission from a hydrogen-terminated Si(111) 1x1 surface and a native SiO{sub 2} thin film on the Si substrate (SiO{sub 2}/Si) irradiated with slow (v{sub ion}

Tona, Masahide; Takahashi, Satoshi; Nagata, Kazuo; Yoshiyasu, Nobuo; Yamada, Chikashi; Nakamura, Nobuyuki; Ohtani, Shunsuke; Sakurai, Makoto [Institute for Laser Science and Department of Applied Physics and Chemistry, University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Department of Physics, Kobe University, Kobe, Hyogo 657-8501 (Japan)

2005-11-28

61

Spectroscopic peculiarities in a 2D Coulomb potential under Aharonov-Bohm effect

NASA Astrophysics Data System (ADS)

In this paper we demonstrate some spectroscopic peculiarities which occur in the presence of the Aharonov-Bohm effect. As an object of investigation the system of a two-dimensional (2D) Coulomb potential in the presence of the Aharonov-Bohm flux is considered. It is shown, that the bound states in such a system “feel” the presence of the magnetic flux. In particular, the numerical analysis shows that the oscillator strengths of optical transitions turn into zero at some “special” values of the Aharonov-Bohm flux. As a result, some spectral lines (namely, the intensities of spectral lines) will disappear and this fact may be considered as an observable optical manifestation of the Aharonov-Bohm effect in the considered system. The dynamic polarisability of the bound states of an electron in such a system is also analyzed. It is shown numerically that the dynamic polarisability “strongly” depends on the values of the Aharonov-Bohm flux.

Meleshenko, Peter A.; Nguyen, Hang T. T.; Klinskikh, Alexander F.

2013-10-01

62

NASA Astrophysics Data System (ADS)

We investigate the coupling of the electromagnetic sources (charge and current densities) to the scalar and vector potentials in classical electrodynamics, using Green function techniques. As is well known, the scalar potential shows an action-at-a-distance behavior in Coulomb gauge. The conundrum generated by the instantaneous interaction has intrigued physicists for a long time. Starting from the differential equations that couple the sources to the potentials, we here show in a concise derivation, using the retarded Green function, how the instantaneous interaction cancels in the calculation of the electric field. The time derivative of a specific additional term in the vector potential, present only in Coulomb gauge, yields a supplementary contribution to the electric field which cancels the gradient of the instantaneous Coulomb gauge scalar potential, as required by gauge invariance. This completely eliminates the contribution of the instantaneous interaction from the electric field. It turns out that a careful formulation of the retarded Green function, inspired by field theory, is required in order to correctly treat boundary terms in partial integrations. Finally, compact integral representations are derived for the Liénard-Wiechert potentials (scalar and vector) in Coulomb gauge which manifestly contain two compensating action-at-a-distance terms.

Wundt, B. J.; Jentschura, U. D.

2012-04-01

63

We investigate the coupling of the electromagnetic sources (charge and current densities) to the scalar and vector potentials in classical electrodynamics, using Green function techniques. As is well known, the scalar potential shows an action-at-a-distance behavior in Coulomb gauge. The conundrum generated by the instantaneous interaction has intrigued physicists for a long time. Starting from the differential equations that couple the sources to the potentials, we here show in a concise derivation, using the retarded Green function, how the instantaneous interaction cancels in the calculation of the electric field. The time derivative of a specific additional term in the vector potential, present only in Coulomb gauge, yields a supplementary contribution to the electric field which cancels the gradient of the instantaneous Coulomb gauge scalar potential, as required by gauge invariance. This completely eliminates the contribution of the instantaneous interaction from the electric field. It turns out that a careful formulation of the retarded Green function, inspired by field theory, is required in order to correctly treat boundary terms in partial integrations. Finally, compact integral representations are derived for the Lienard-Wiechert potentials (scalar and vector) in Coulomb gauge which manifestly contain two compensating action-at-a-distance terms.

B. J. Wundt; U. D. Jentschura

2011-10-27

64

Information-Theoretic Properties of the Half-Line Coulomb Potential

The half-line one-dimensional Coulomb potential is possibly the simplest D-dimensional model with physical solutions which has been proved to be successful to describe the behaviour of Rydberg atoms in external fields and the dynamics of surface-state electrons in liquid helium, with potential applications in constructing analog quantum computers and other fields. Here, we investigate the spreading and uncertaintylike properties for the ground and excited states of this system by means of the logarithmic measure and the information-theoretic lengths of Renyi, Shannon and Fisher types; so, far beyond the Heisenberg measure. In particular, the Fisher length (which is a local quantity of internal disorder) is shown to be the proper measure of uncertainty for our system in both position and momentum spaces. Moreover the position Fisher length of a given physical state turns out to be not only directly proportional to the number of nodes of its associated wavefunction, but also it follows a square-root energy law.

J. J. Omiste; R. J. Yanez; J. S. Dehesa

2009-09-02

65

NASA Astrophysics Data System (ADS)

We present two analytical methods, Taylor expansion and Gegenbauer expansion, to efficiently and accurately calculate the two-electron screened Coulomb potential matrix elements with Slater-type configuration-interaction basis functions. The former permits great advantages in fast computation of the potential matrices at small screening parameters and the latter allows accurate calculation of the matrices at all screening parameters. The bound and resonant states of a He atom embedded in the screening environment are calculated by employing the variational and complex-scaling methods, respectively, and the results are compared with other theoretical predictions. The expectation values of some physical quantities for He ground state are compared with the recent calculation of Ancarani and Rodriguez [Phys. Rev. A 89, 012507 (2014), 10.1103/PhysRevA.89.012507] and extended to stronger screening environment. The energies and widths for the doubly excited resonant states are in good agreement with previous calculations, while the interelectronic angle arccos

Jiao, Li Guang; Ho, Yew Kam

2014-07-01

66

Effective Coulomb logarithm for one component plasma

An expression for the effective Coulomb logarithm in one-component-plasma is proposed, which allows to extend the applicability of the classical formula for the self-diffusion coefficient to the strongly coupled regime. The proposed analytical approximation demonstrates reasonable agreement with previous numerical simulation results. Relevance to weakly screened Yukawa systems (and, in particular, complex plasmas) is discussed.

Khrapak, Sergey A. [Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany)] [Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany)

2013-05-15

67

NASA Astrophysics Data System (ADS)

The energy spectra of spherically confined hydrogen atom embedded in an exponential-cosine-screened Coulomb potential is worked out by using the Bernstein-polynomial method. The interaction of short laser pulses in the femtosecond range with the system is studied in detail. The effect of shape of laser pulse, confinement radius, Debye screening length as well as different laser parameters on the dynamics of the system has been explored and analyzed.

Lumb, Shalini; Lumb, Sonia; Prasad, Vinod

2014-09-01

68

We investigate in detail "instantaneous interquark potentials", interesting gauge-dependent quantities defined from the spatial correlators of the temporal link-variable $U_4$, in generalized Landau gauge using SU(3) quenched lattice QCD. The instantaneous Q$\\bar{\\rm Q}$ potential has no linear part in the Landau gauge, and it is expressed by the Coulomb plus linear potential in the Coulomb gauge, where the slope is 2-3 times larger than the physical string tension. Using the generalized Landau gauge, we find that the instantaneous potential can be continuously described between the Landau and the Coulomb gauges, and its linear part rapidly grows in the neighborhood of the Coulomb gauge. We also investigate the instantaneous 3Q potential in the generalized Landau gauge, and obtain similar results to the Q$\\bar{\\rm Q}$ case. $T$-length terminated Polyakov-line correlators and their corresponding "finite-time potentials" are also investigated in generalized Landau gauge.

Takumi Iritani; Hideo Suganuma

2011-02-04

69

We investigate in detail 'instantaneous interquark potentials', interesting gauge-dependent quantities defined from the spatial correlators of the temporal link-variable U{sub 4}, in generalized Landau gauge using SU(3) quenched lattice QCD. The instantaneous QQ potential has no linear part in the Landau gauge, and it is expressed by the Coulomb plus linear potential in the Coulomb gauge, where the slope is 2-3 times larger than the physical string tension. Using the generalized Landau gauge, we find that the instantaneous potential can be continuously described between the Landau and the Coulomb gauges, and its linear part rapidly grows in the neighborhood of the Coulomb gauge. We also investigate the instantaneous 3Q potential in the generalized Landau gauge, and obtain similar results to the QQ case. T-length terminated Polyakov-line correlators and their corresponding ''finite-time potentials'' are also investigated in generalized Landau gauge.

Iritani, Takumi; Suganuma, Hideo [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake, Sakyo, Kyoto 606-8502 (Japan)

2011-03-01

70

Anomalous Higgs Yukawa couplings

NASA Astrophysics Data System (ADS)

In the standard model, the Higgs boson h couples to the quarks and charged leptons according to the well-known formula (m_\\psi/v) h \\bar{\\psi}\\psi , where \\psi =\\text{quark }(q) or lepton (l) and v = 246 \\text{GeV} is its vacuum expectation value. Suppose m_\\psi is of radiative origin instead, then the effective h \\bar{\\psi} \\psi Yukawa coupling will not be exactly m_\\psi/v . We show for the first time quantitatively how this may shift the observed branching fractions of h \\to \\bar{b} b and h \\to ?+ ?- upward or downward. Thus, the precision measurements of the Higgs decay to fermions at the Large Hadron Collider, due to the resume operation in 2015, could be the key to possible new physics.

Fraser, Sean; Ma, Ernest

2014-10-01

71

Yukawa-type effects in satellite dynamics

NASA Astrophysics Data System (ADS)

Many of today's gravity theories predict the existence of a non-Newtonian Yukawa-type correction to the gravitational potential. New experimental techniques, such as Sagnac interferometry, may help in exploring the range ??1014 m where such forces are possibly measurable. It is expected that future space missions will operate in this range, which has not been examined for a very long time. Restricting ourselves to an Earth orbiting satellite we follow a perturbing-potential approach applied on the Lagrange planetary equations, in order to study the effect of such a non-Newtonian potential in the range ??1.073 R E. This is achieved by calculating the time rates of change of the orbital elements for the earth orbiting satellite GRACE-A. All these time rates have been calculated on the Keplerian and the precessing Keplerian ellipse of the body under study. Of all the orbital elements, the argument of the perigee is most affected by this potential.

Haranas, Ioannis; Ragos, Omiros

2011-01-01

72

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.

Greensite, J.; Olejnik, S.

2003-09-26

73

We present a light-front calculation of the box diagram in Yukawa theory. The covariant box diagram is finite for the case of spin-1/2 constituents exchanging spin-0 particles. In light-front dynamics, however, individual time-ordered diagrams are divergent. We analyze the corresponding light-front singularities and show the equivalence between the light-front and covariant results by taming the singularities.

Bakker, Bernard L. G.; Boomsma, Jorn K. [Department of Physics and Astrophysics, Vrije Universiteit, De Boelelaan 1081, NL-1081 HV Amsterdam (Netherlands); Ji, Chueng-Ryong [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)

2007-03-15

74

Mixing parameters of neutral beauty mesons from the Coulomb plus power potential (CPP?)

NASA Astrophysics Data System (ADS)

The investigation of mixing parameters in neutral B meson systems provides an important testing ground for standard model flavour dynamics. The spectroscopic parameters deduced from the potential model are used to calculate the pseudoscalar decay constant and mixing parameters of the B and Bs mesons.

Patel, Bhavin; Vinodkumar, P. C.

2009-11-01

75

Probing the top-Yukawa coupling in associated Higgs production with a single top quark

NASA Astrophysics Data System (ADS)

Associated production of the Higgs boson with a single top quark proceeds through Feynman diagrams, which are either proportional to the hW W , top-Yukawa, or the bottom-Yukawa couplings. It was shown in literature that the interference between the top-Yukawa and the gauge-Higgs diagrams can be significant, and thus the measurement of the cross sections can help pin down the sign and the size of the top-Yukawa coupling. Here we perform a detailed study with full detector simulations of such a possibility at the LHC-14 within the current allowed range of hW W and top-Yukawa couplings, using h ? b , ?? , ? + ? - , ZZ * ? 4 ? modes. We found that the LHC-14 has the potential to distinguish the size and the sign of the top-Yukawa coupling. Among the channels the h ? b mode provides the best chance to probe the signal, followed by the h ? ?? mode, which has the advantage of a narrow reconstructed mass peak. We also pointed out that the spatial separation among the final-state particles has the potential in differentiating among various values of the top-Yukawa coupling.

Chang, Jung; Cheung, Kingman; Lee, Jae Sik; Lu, Chih-Ting

2014-05-01

76

NSDL National Science Digital Library

This Flash simulation allows you to observe the force on a charge due to an identical charge. The a graph of Coulomb force experienced by one of the charges due to the other charge is shown. The user can move both charges.

Selen, Mats

2010-03-11

77

In this work, we discuss the relativistic Landau–He–McKellar–Wilkens quantization and relativistic bound states solutions for a Dirac neutral particle under the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects. We present new possible scenarios of studying Lorentz symmetry breaking effects by fixing the space-like vector field background in special configurations. It is worth mentioning that the criterion for studying the violation of Lorentz symmetry is preserving the gauge symmetry. -- Highlights: •Two new possible scenarios of studying Lorentz symmetry breaking effects. •Coulomb-like potential induced by the Lorentz symmetry breaking effects. •Relativistic Landau–He–McKellar–Wilkens quantization. •Exact solutions of the Dirac equation.

Bakke, K., E-mail: kbakke@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-970, João Pessoa, PB (Brazil); Belich, H. [Departamento de Física e Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, 29060-900, Vitória, ES (Brazil)] [Departamento de Física e Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, 29060-900, Vitória, ES (Brazil)

2013-06-15

78

An improved approach is presented for calculating pH-dependent electrostatic effects in proteins using sigmoidally screened Coulomb potentials (SCP). It is hypothesized that a key determinant of seemingly aberrant behavior in pKa shifts is due to the properties of the unique microenvironment around each residue. To help demonstrate this proposal, an approach is developed to characterize the microenvironments using the local hydrophobicity/hydrophilicity around each residue of the protein. The quantitative characterization of the microenvironments shows that the protein is a complex mosaic of differing dielectric regions that provides a physical basis for modifying the dielectric screening functions: in more hydrophobic microenvironments the screening decreases whereas the converse applies to more hydrophilic regions. The approach was applied to seven proteins providing more than 100 measured pKa values and yielded a root mean square deviation of 0.5 between calculated and experimental values. The incorporation of the local hydrophobicity characteristics into the algorithm allowed the resolution of some of the more intractable problems in the calculation of pKa. Thus, the divergent shifts of the pKa of Glu-35 and Asp-66 in hen egg white lysozyme, which are both about 90% buried, was correctly predicted. Mechanistically, the divergence occurs because Glu-35 is in a hydrophobic microenvironment, while Asp-66 is in a hydrophilic microenvironment. Furthermore, because the calculation of the microenvironmental effects takes very little CPU time, the computational speed of the SCP formulation is conserved. Finally, results from different crystal structures of a given protein were compared, and it is shown that the reliability of the calculated pKa values is sufficient to allow identification of conformations that may be more relevant for the solution structure. PMID:10388736

Mehler, E L; Guarnieri, F

1999-01-01

79

In this paper we have performed the calculus of the energy states of hydrogen atom by using the Schroedinger equation with a Coulomb potential which is modified by the interaction between the magnetic moments of the proton and the electron, respectively. The important result is that the Lamb shift appears as a natural result of the solution of Schroedinger equation. The obtained results are in a good agreement with experimental data.

Voicu Dolocan

2014-03-26

80

An alternative Yukawa unified SUSY scenario

NASA Astrophysics Data System (ADS)

Supersymmetric SO(10) Grand Unified Theories with Yukawa unification represent an appealing possibility for physics beyond the Standard Model. However Yukawa unification is made difficult by large threshold corrections to the bottom mass. Generally one is led to consider models where the sfermion masses are large in order to suppress these corrections. Here we present another possibility, in which the top and bottom GUT scale Yukawa couplings are equal to a component of the charged lepton Yukawa matrix at the GUT scale in a basis where this matrix is not diagonal. Physically, this weak eigenstate Yukawa unification scenario corresponds to the case where the charged leptons that are in the 16 of SO(10) containing the top and bottom quarks mix with their counterparts in another SO(10) multiplet. Diagonalizing the resulting Yukawa matrix introduces mixings in the neutrino sector. Specifically we find that for a large region of parameter space with relatively light sparticles, and which has not been ruled out by current LHC or other data, the mixing induced in the neutrino sector is such that sin2 2 ? 23 ? 1, in agreement with data. The phenomenological implications are analyzed in some detail.

Gainer, James S.; Huo, Ran; Wagner, Carlos E. M.

2012-03-01

81

NASA Astrophysics Data System (ADS)

The thermal conductivity of two-dimensional (2D) complex (dusty) plasma liquids (CDPLs) has been explored using a homogenous nonequilibrium molecular dynamics (HNEMD) technique in a canonical ensemble, for the first time. The effects of an external force field along with different plasma parameters of the Coulomb coupling (\\varGamma ) and screening (?) strengths on the thermal conductivity of CDPLs have been investigated using improved HNEMD simulations. The new simulations show that the thermal conductivity is dependent on the temperature in the 2D Yukawa liquids and provides more reliable results than previously known numerical results. It is shown that a simple analytical temperature representation of Yukawa thermal conductivities with a suitable normalized Einstein frequency is performed. The obtained simulation results are in satisfactory agreement with the earlier nonequilibrium molecular dynamics, equilibrium molecular dynamics simulations, and experimental data, for the whole range of plasma parameters (\\varGamma , ?).

Shahzad, Aamir; He, Mao-Gang

2014-07-01

82

Molecular dynamics simulations of thermal conductivity in 2D complex Yukawa liquids

NASA Astrophysics Data System (ADS)

The thermal conductivity in strongly coupled complex dusty plasma liquids (SCCDPLs) has been investigated through an improved homogenous nonequilibrium molecular simulation (HNEMS) method, for the first time. The HNEMS method has been employed for two-dimensional (2D) Yukawa systems in a canonical ensemble. The thermal conductivities with suitable normalizations (plasma and Einstein frequencies), in the value of low force field strength, have been computed for a wide range of plasma state points of Coulomb coupling (?) and screening strength (?). The new simulation results are found to obey the simple analytical temperature scaling law. The present HNEMS results are in generally with parts of earlier HNEMS, equilibrium molecular dynamics (EMD) and experimental data in the literature for the 2D and there-dimensional (3D) SCCDPLs. It is shown that the HNEMS method can be used to estimate the thermal conductivity very effectively and to understand the fundamental behaviours in 2D Yukawa systems.

Shahzad, Aamir; Sultana, Mariam; Aslam, Arffa; He, Mao-Gang

2014-06-01

83

We decouple the Dirac's radial equations in $D+1$ dimensions with Coulomb-type scalar and vector potentials through appropriate transformations. We study each of these uncoupled second-order equations in an algebraic way by using an $su(1,1)$ algebra realization. Based on the theory of irreducible representations, we find the energy spectrum and the radial eigenfunctions. We construct the Perelomov coherent states for the Sturmian basis, which is the basis for the unitary irreducible representation of the $su(1,1)$ Lie algebra. The physical radial coherent states for our problem are obtained by applying the inverse original transformations to the Sturmian coherent states.

D. Ojeda-Guillen; R. D. Mota; V. D. Granados

2013-11-12

84

Relativistic Newton and Coulomb Laws

The relativistic equations for the electromagnetic and gravitation interactions are similar: The only Lagrangian equation is the equation with Lorentz force. The potential satisfies the wave equation with the right - hand side proprtional to the velocity of another particle multiplied by the delta - function concentrated at the position of another particle. If the interaction propagates at the speed of light, then the wave equation has the unique solution: the Lienard - Wiechert potential. The Maxwell equations are completely defined by the obtained relativistic Coulomb law. The Coulomb law and the Newton gravity law differ from each other only in the choice of the constants. If we choose in Coulomb law the electric charges equal to the masses and choose the interaction constant of another sign, then we get Newton gravity law. If we choose in the relativistic Coulomb law the electric charges equal to the masses and choose the interaction constant of another sign, then we get the relativistic Newton gravity la...

Zinoviev, Yury M

2008-01-01

85

Relativistic Newton and Coulomb Laws

The relativistic equations for the electromagnetic and gravitation interactions are similar: The only Lagrangian equation is the equation with Lorentz force. The potential satisfies the wave equation with the right - hand side proprtional to the velocity of another particle multiplied by the delta - function concentrated at the position of another particle. If the interaction propagates at the speed of light, then the wave equation has the unique solution: the Lienard - Wiechert potential. The Maxwell equations are completely defined by the obtained relativistic Coulomb law. The Coulomb law and the Newton gravity law differ from each other only in the choice of the constants. If we choose in Coulomb law the electric charges equal to the masses and choose the interaction constant of another sign, then we get Newton gravity law. If we choose in the relativistic Coulomb law the electric charges equal to the masses and choose the interaction constant of another sign, then we get the relativistic Newton gravity law.

Yury M. Zinoviev

2008-01-07

86

NASA Astrophysics Data System (ADS)

We previously reported a screened Hartree-Fock (HF) exchange potential for energy band structure calculations [T. Shimazaki and Y. Asai, J. Chem. Phys. 130, 164702 (2009); T. Shimazaki and Y. Asai, J. Chem. Phys. 132, 224105 (2010)]. In this paper, we discuss the Coulomb-hole (COH) interaction and screened Slater-formula and determine the energy band diagrams of several semiconductors, such as diamond, silicon, AlAs, AlP, GaAs, GaP, and InP, based on the screened HF exchange potential and Slater-formula with COH interaction, to demonstrate the adequacy of those theoretical concepts. The screened HF exchange potential and Slater-formula are derived from a simplified dielectric function and, therefore, include the dielectric constant in their expressions. We also present a self-consistent calculation technique to automatically determine the dielectric constant, which is incorporated into each self-consistent field step.

Shimazaki, Tomomi; Nakajima, Takahito

2014-09-01

87

Determining the SUSY-QCD Yukawa Coupling

Among the firm predictions of softly broken supersymmetry is the identity of gauge couplings and the corresponding Yukawa couplings between gauginos, sfermions and fermions. In the event that a SUSY-like spectrum of new particles is discovered at future colliders, a key follow-up will be to test these relations experimentally. In detailed studies it has been found that the SUSY-Yukawa couplings of the electroweak sector can be studied with great precision at the ILC, but a similar analysis for the Yukawa coupling of the SUSY-QCD sector is far more challenging. Here a first phenomenological study for determining this coupling is presented, using a method which combines information from LHC and ILC.

Ayres Freitas; Peter Z Skands

2006-06-09

88

NASA Astrophysics Data System (ADS)

We analyse the effect of the long-range potential of the ionic core on the photoelectron emission in atomic ionization by a linearly polarized subcycle sculpted laser pulse of two-colour components, where one frequency doubles the other. The total ionization yield consists mostly of direct electrons, which can be characterized by both intracycle and intercycle interferences. Using a semiclassical model based on the Simple Man’s Model, we can derive an analytical expression for the intracycle interference due to the coherent superposition of different electron trajectories released in the same sculpted optical cycle. In turn, the intercycle interference is the consequence of the superposition of multiple trajectories released at different cycles and is accounted for by the energy conservation in the photon absorption process. We show that a semiclassical description in terms of a diffraction process at a time grating for two-colour laser pulses remains qualitatively unchanged beyond the strong field approximation. In particular, the Coulomb potential shifts the intracycle interference modulations towards the threshold, whereas the intercycle interference pattern remains invariant. The present study completes a recent work by Xie et al (2013 New J. Phys. 15 043050), where the influence of the Coulomb field on atomic ionization by sculpted two-colour laser fields is probed but in which path interferences are not considered. Furthermore, this article gives theoretical support to recent experiments with He and Ar where the sub-cycle interference structures originating from trajectories launched within a time interval of less than one femtosecond were observed (Xie X et al 2012 Phys. Rev. Lett. 108 193004).

Arbó,

2014-10-01

89

NASA Astrophysics Data System (ADS)

Angular distributions of elastic scattering and inelastic scattering from 2 +1 state are measured for 16O+ 142,144,146Nd systems at several energies in the vicinity of the Coulomb barrier. The angular distributions are systematically analyzed in coupled channel framework. Renormalized double folded real optical and coupling potentials with DDM3Y interaction have been used in the calculation. Relevant nuclear densities needed to generate the potentials are derived from shell model wavefunctions. A truncated shell model calculation has been performed and the calculated energy levels are compared with the experimental ones. To simulate the absorption, a 'hybrid' approach is adopted. The contribution to the imaginary potential of couplings to the inelastic channels, other than the 2 +1 target excitation channel, is calculated in the Feshbach formalism. This calculated imaginary potential along with a short ranged volume Woods-Saxon potential to simulate the absorption in fusion channel reproduces the angular distributions for 16O+ 146Nd quite well. But for 16O+ 142,144Nd systems additional surface absorption is found to be necessary to fit the angular distribution data. The variations of this additional absorption term with incident energy and the mass of the target are explored.

Mandal, Samit; Madhusoodhanan, T.; Roy, Subinit; Ray, S.; Majumdar, H.; Datta, S.; Ghugre, S. S.; Ghosh, S.; Mandal, A.; Avasthi, D. K.; Datta, S. K.

2003-06-01

90

Yukawa Textures From Heterotic Stability Walls

A holomorphic vector bundle on a Calabi-Yau threefold, X, with h^{1,1}(X)>1 can have regions of its Kahler cone where it is slope-stable, that is, where the four-dimensional theory is N=1 supersymmetric, bounded by "walls of stability". On these walls the bundle becomes poly-stable, decomposing into a direct sum, and the low energy gauge group is enhanced by at least one anomalous U(1) gauge factor. In this paper, we show that these additional symmetries can strongly constrain the superpotential in the stable region, leading to non-trivial textures of Yukawa interactions and restrictions on allowed masses for vector-like pairs of matter multiplets. The Yukawa textures exhibit a hierarchy; large couplings arise on the stability wall and some suppressed interactions "grow back" off the wall, where the extended U(1) symmetries are spontaneously broken. A number of explicit examples are presented involving both one and two stability walls, with different decompositions of the bundle structure group. A three family standard-like model with no vector-like pairs is given as an example of a class of SU(4) bundles that has a naturally heavy third quark/lepton family. Finally, we present the complete set of Yukawa textures that can arise for any holomorphic bundle with one stability wall where the structure group breaks into two factors.

Lara B. Anderson; James Gray; Burt Ovrut

2010-01-13

91

Based on a recent result showing that the net Coulomb potential in condensed ionic systems is rather short ranged, an exact and physically transparent method permitting the evaluation of the Coulomb potential by direct summation over the r-1 Coulomb pair potential is presented. The key observation is that the problems encountered in determining the Coulomb energy by pairwise, spherically truncated

D. Wolf; P. Keblinski; S. R. Phillpot; J. Eggebrecht

1999-01-01

92

NASA Astrophysics Data System (ADS)

We consider a classical model of charges ±q on a pyrochlore lattice in the presence of long-range Coulomb interactions. This model first appeared in the early literature on charge order in magnetite [P. W. Anderson, Phys. Rev. 102, 1008 (1956), 10.1103/PhysRev.102.1008]. In the limit where the interactions become short ranged, the model has a ground state with an extensive entropy and dipolar charge-charge correlations. When long-range interactions are introduced, the exact degeneracy is broken. We study the thermodynamics of the model and show the presence of a correlated charge liquid within a temperature window in which the physics is well described as a liquid of screened charged defects. The structure factor in this phase, which has smeared pinch points at the reciprocal lattice points, may be used to detect charge ice experimentally. In addition, the model exhibits fractionally charged excitations ±q/2 which are shown to interact via a 1/r potential. At lower temperatures, the model exhibits a transition to a long-range ordered phase. We are able to treat the Coulombic charge ice model and the dipolar spin ice model on an equal footing by mapping both to a constrained charge model on the diamond lattice. We find that states of the two ice models are related by a staggering field which is reflected in the energetics of these two models. From this perspective, we can understand the origin of the spin ice and charge ice ground states as coming from a dipolar model on a diamond lattice. We study the properties of charge ice in an external electric field, finding that the correlated liquid is robust to the presence of a field in contrast to the case of spin ice in a magnetic field. Finally, we comment on the transport properties of Coulombic charge ice in the correlated liquid phase.

McClarty, P. A.; O'Brien, A.; Pollmann, F.

2014-05-01

93

Exploring the dark side of the top Yukawa

We investigate simple extensions of the Standard Model that could lead to the negative values of the top Yukawa coupling still allowed by the ATLAS Higgs results. Integrating out tree-level new physics generates dimension six operators that can lead to large changes to the top Yukawa couplings. If the top Yukawa coupling is negative, there is new physics beneath the TeV scale. We illustrate the simplest models still allowed by current searches.

Sonia El Hedri; Patrick J. Fox; Jay G. Wacker

2013-11-25

94

The Nuclear Yukawa Model on a Lattice

We present the results of the quantum field theory approach to nuclear Yukawa model obtained by standard lattice techniques. We have considered the simplest case of two identical fermions interacting via a scalar meson exchange. Calculations have been performed using Wilson fermions in the quenched approximation. We found the existence of a critical coupling constant above which the model cannot be numerically solved. The range of the accessible coupling constants is below the threshold value for producing two-body bound states. Two-body scattering lengths have been obtained and compared to the non relativistic results.

F. de Soto; J. C. Angles d'Auriac; J. Carbonell

2011-04-11

95

Ab initio nonperturbative calculations in Yukawa model

NASA Astrophysics Data System (ADS)

We give a brief review of a nonperturbative approach to field theory based on the decomposition of the state vector in Fock components, and on the covariant formulation of light-front dynamics, together with the Fock sector dependent renormalization scheme. The approach is applied to the calculation, in the three-body Fock space truncation, of electromagnetic form factors of a fermion in the Yukawa model (in particular, of anomalous magnetic moment). Once the renormalization conditions are properly taken into account, the anomalous magnetic moment does not depend on the regularization scale, when the latter is much larger than the physical masses.

Karmanov, V. A.

2014-06-01

96

Yukawa interactions and supersymmetric electroweak baryogenesis.

We analyze the quantum transport equations for supersymmetric electroweak baryogenesis including previously neglected bottom and tau Yukawa interactions and show that they imply the presence of a previously unrecognized dependence of the cosmic baryon asymmetry on the spectrum of third generation quark and lepton superpartners. For fixed values of the CP-violating phases in the supersymmetric theory, the baryon asymmetry can vary in both magnitude and sign as a result of the squark and slepton mass dependence. For light, right-handed top and bottom quark superpartners, the baryon number creation can be driven primarily by interactions involving third generation leptons and their superpartners. PMID:19257576

Chung, Daniel J H; Garbrecht, Björn; Ramsey-Musolf, Michael J; Tulin, Sean

2009-02-13

97

Higgs Boson Yukawa Form Factors from Supersymmetric Radiative Fermion Masses

The recent discovery of the Higgs-like resonance at $125\\,\\rm{GeV}$ has opened up new avenues in the search for beyond standard model physics. Hints of such extensions could manifest themselves as modifications in the Higgs-fermion couplings and other Higgs related observables. In this work, we study aspects of a class of models where the light fermion masses are radiatively generated. Specifically, we consider models where the light fermion masses, partially or completely, arise from chiral violation in the soft supersymmetry-breaking sector. In these models, the radiatively generated Higgs-fermion Yukawa form factors have non-trivial characteristics and will modify Higgs-fermion couplings from their standard model expectations. A radiatively generated fermion mass could also potentially contribute to large anomalous magnetic moments; this is particularly interesting in the case of the muon where a persistent discrepancy, at the level of around $3\\,\\sigma$, has existed between experiment and theory. Deviatio...

Thalapillil, Arun

2014-01-01

98

Statics and dynamics of Yukawa cluster crystals on ordered substrates.

We examine the statics and dynamics of particles with repulsive Yukawa interactions in the presence of a two-dimensional triangular substrate for fillings of up to 12 particles per potential minimum. We term the ordered states Yukawa cluster crystals and show that they are distinct from the colloidal molecular crystal states found at low fillings. As a function of substrate and interaction strength at fixed particle density we find a series of novel crystalline states that we characterize using the structure factor. For fillings greater than four, shell and ring structures form at each potential minimum and can exhibit sample-wide orientational order. A disordered state can appear between ordered states as the substrate strength varies. Under an external drive, the onsets of different orderings produce clear changes in the critical depinning force, including a peak effect phenomenon that has generally only previously been observed in systems with random substrates. We also find a rich variety of dynamic ordering transitions that can be observed via changes in the structure factor and features in the velocity-force curves. The dynamical states encompass a variety of moving structures including one-dimensional stripes, smectic ordering, polycrystalline states, triangular lattices, and symmetry locking states. Despite the complexity of the system, we identify several generic features of the dynamical phase transitions which we map out in a series of phase diagrams. Our results have implications for the structure and depinning of colloids on periodic substrates, vortices in superconductors and Bose-Einstein condensates, Wigner crystals, and dusty plasmas. PMID:23004755

Reichhardt, C; Olson Reichhardt, C J

2012-05-01

99

NASA Astrophysics Data System (ADS)

Four potential energy surfaces are of current interest for the Ne-CO interaction. Two are high-level fully ab initio surfaces obtained a decade ago using symmetry-adapted perturbation theory and supermolecule coupled-cluster methods. The other two are very recent exchange-Coulomb (XC) model potential energy surfaces constructed by using ab initio Heitler-London interaction energies and literature long range dispersion and induction energies, followed by the determination of a small number of adjustable parameters to reproduce a selected subset of pure rotational transition frequencies for the 20Ne-12C16O van der Waals cluster. Testing of the four potential energy surfaces against a wide range of available experimental microwave, millimeter-wave, and mid-infrared Ne-CO transition frequencies indicated that the XC potential energy surfaces gave results that were generally far superior to the earlier fully ab initio surfaces. In this paper, two XC model surfaces and the two fully ab initio surfaces are tested for their abilities to reproduce experiment for a wide range of nonspectroscopic Ne-CO gas mixture properties. The properties considered here are relative integral cross sections and the angle dependence of rotational state-to-state differential cross sections, rotational relaxation rate constants for CO(v=2) in Ne-CO mixtures at T=296 K, pressure broadening of two pure rotational lines and of the rovibrational lines in the CO fundamental and first overtone transitions at 300 K, and the temperature and, where appropriate, mole fraction dependencies of the interaction second virial coefficient, the binary diffusion coefficient, the interaction viscosity, the mixture shear viscosity and thermal conductivity coefficients, and the thermal diffusion factor. The XC model potential energy surfaces give results that lie within or very nearly within the experimental uncertainties for all properties considered, while the coupled-cluster ab initio surface gives results that agree similarly well for all but one of the properties considered. When the present comparisons are combined with the ability to give accurate spectroscopic transition frequencies for the Ne-CO van der Waals complex, only the XC potential energy surfaces give results that agree well with all extant experimental data for the Ne-CO interaction.

Dham, Ashok K.; McBane, George C.; McCourt, Frederick R. W.; Meath, William J.

2010-01-01

100

Effective Potential Theory: A Practical Way to Extend Plasma Transport Theory to Strong Coupling

The effective potential theory is a physically motivated method for extending traditional plasma transport theories to stronger coupling. It is practical in the sense that it is easily incorporated within the framework of the Chapman-Enskog or Grad methods that are commonly applied in plasma physics and it is computationally efficient to evaluate. The extension is to treat binary scatterers as interacting through the potential of mean force, rather than the bare Coulomb or Debye-screened Coulomb potential. This allows for aspects of many-body correlations to be included in the transport coefficients. Recent work has shown that this method accurately extends plasma theory to orders of magnitude stronger coupling when applied to the classical one-component plasma model. The present work shows that similar accuracy is realized for the Yukawa one-component plasma model and it provides a comparison with other approaches.

Baalrud, Scott D; Daligault, Jerome

2014-01-01

101

NASA Astrophysics Data System (ADS)

The structure and thermodynamics of strongly coupled dusty plasmas are investigated with the soft mean spherical approximation. This integral theory approach is analytically solvable for Yukawa pair interactions yielding a closed-form solution for the direct correlation function. The pair correlation function, the structure factor, and basic thermodynamic quantities are calculated for a wide range of parameters. Exact consistency between the "energy"-"virial" thermodynamic routes and approximate consistency between the "energy"-"compressibility" paths is demonstrated. Comparison with extensive molecular dynamics results is carried out and a remarkable agreement from the Coulomb limit to the strongly screened limit is revealed. The soft mean spherical approximation is concluded to be particularly well suited for the study of dusty plasma liquids, uniquely combining simplicity and accuracy.

Tolias, P.; Ratynskaia, S.; de Angelis, U.

2014-11-01

102

Numerical approach to Coulomb gauge QCD

We calculate the ghost two-point function in Coulomb gauge QCD with a simple model vacuum gluon wave function using Monte Carlo integration. This approach extends the previous analytic studies of the ghost propagator with this ansatz, where a ladder-rainbow expansion was unavoidable for calculating the path integral over gluon field configurations. The new approach allows us to study the possible critical behavior of the coupling constant, as well as the Coulomb potential derived from the ghost dressing function. We demonstrate that IR enhancement of the ghost correlator or Coulomb form factor fails to quantitatively reproduce confinement using Gaussian vacuum wave functional.

Matevosyan, Hrayr H.; Szczepaniak, Adam P.; Bowman, Patrick O. [Department of Physics and Nuclear Theory Center, Indiana University, Bloomington, Indiana, 47405 (United States); Centre of Theoretical Chemistry and Physics, Institute of Fundamental Sciences, Massey University (Auckland), Private Bag 102904, NSMSC, Auckland (New Zealand)

2008-07-01

103

Diffusion in coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants $D$ from molecular dynamics simulations. We find that $D$ for coulomb crystals with relatively soft-core $1/r$ interactions may be larger than $D$ for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ring-like configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from coulomb parameter $\\Gamma=175$ to coulomb parameters up to $\\Gamma=1750$, is fast enough so that the system starts to crystallize during long simulation runs. These results strongly suggest that coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

J. Hughto; A. S. Schneider; C. J. Horowitz; D. K. Berry

2011-04-25

104

Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions ''hop'' in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter {Gamma}=175 to Coulomb parameters up to {Gamma}=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

Hughto, J.; Schneider, A. S.; Horowitz, C. J.; Berry, D. K. [Department of Physics and Nuclear Theory Center, Indiana University, Bloomington, Indiana 47405 (United States); University Information Technology Services, Indiana University, Bloomington, Indiana 47408 (United States)

2011-07-15

105

Three different approaches to the same interaction: the Yukawa model in nuclear physics

After a brief discussion of the meaning of the potential in quantum mechanics, we examine the results of the Yukawa model (scalar meson exchange) for the nucleon-nucleon interaction in three different dynamical frameworks: the non-relativistic dynamics of the Schrodinger equation, the relativistic quantum mechanics of the Bethe-Salpeter and Light-Front equations and the lattice solution of the Quantum Field Theory, obtained in the quenched approximation.

J. Carbonell; F. de Soto; V. A. Karmanov

2012-11-23

106

Analysis of two-dimensional photoelectron momentum spectra and the effect of the long-range Coulomb 2006 Two-dimensional 2D electron momentum distributions and energy spectra for multiphoton ionization . It is shown that the momentum spectra at low energies between the TDSE and SFA are quite different

Lin, Chii-Dong

107

Ion sphere model for Yukawa systems (dusty plasmas)

Application of the ion sphere model (ISM), well known in the context of the one-component-plasma, to estimate thermodynamic properties of model Yukawa systems is discussed. It is shown that the ISM approximation provides fairly good estimate of the internal energy of the strongly coupled Yukawa systems, in both fluid and solid phases. Simple expressions for the excess pressure and isothermal compressibility are derived, which can be particularly useful in connection to wave phenomena in strongly coupled dusty plasmas. It is also shown that in the regime of strong screening a simple consideration of neighboring particles interactions can be sufficient to obtain quite accurate estimates of thermodynamic properties of Yukawa systems.

S. A. Khrapak; A. G. Khrapak; A. V. Ivlev; H. M. Thomas

2014-10-08

108

Ion sphere model for Yukawa systems (dusty plasmas)

Application of the ion sphere model (ISM), well known in the context of the one-component-plasma, to estimate thermodynamic properties of model Yukawa systems is discussed. It is shown that the ISM approximation provides fairly good estimate of the internal energy of the strongly coupled Yukawa systems, in both fluid and solid phases. Simple expressions for the excess pressure and isothermal compressibility are derived, which can be particularly useful in connection to wave phenomena in strongly coupled dusty plasmas. It is also shown that in the regime of strong screening a simple consideration of neighboring particles interactions can be sufficient to obtain quite accurate estimates of thermodynamic properties of Yukawa systems.

Khrapak, S A; Ivlev, A V; Thomas, H M

2014-01-01

109

NSDL National Science Digital Library

A PhysLet based simulation using a graphical approach to explore Coulomb's law. In this interesting problem, the user has to identify three charges based on the trajectory that a test charge follows and based on the force graph.

Papadopoulos, Costas

2008-06-24

110

Variational Bound States of Screened Potentials

NASA Astrophysics Data System (ADS)

Anumber of years ago, a calculational scheme was introduced by Stubbins [Phys. Rev. A48, 220 (1993)] to compute the energies of both the Hulthén and Yukawa potentials. The method introduces a particular ansatz for solving the Schrödinger equation with screened Coulomb type potentials. In this work, we wish to review the method of Stubbins and to show that it is, in fact, equivalent and a subset of a more systematic (and hence more useful) variational scheme [Zhou et al. Phys. Rev. A51, 3337 (1995)]. This variational approach involves the construction of a basis by taking derivatives of the variational parameters of the system. The eigenvalues of the Hamiltonian matrix are then minimized with respect to these parameters yielding a "best guess" upper bound on the energies.

Mancini, Jay D.; Fessatidis, Vassilios; K. Murawski, Robert; Bowen, Samuel P.

2014-08-01

111

The total fusion cross sections for the fusion of weakly bound $^{9}$Be on $^{27}$Al and $^{64}$Zn targets at near and above the barrier have been calculated using one dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential and the calculated values are compared with experimental data. For the purpose of comparison of the fusion of weakly bound projectiles and strongly bound projectiles, the total fusion cross sections for the reaction of tightly bound nucleus $^{16}$O on $^{64}$Zn have also been computed using a similar procedure. The calculated values of total fusion cross sections in all cases are compared with coupled channel calculations using the code CCFULL. The computed cross sections using Coulomb and proximity potential explain the fusion reactions well in both cases of weakly bound and strongly bound projectiles. Reduced reaction cross sections for the systems $^{9}$Be + $^{27}$Al, $^{9}$Be+ $^{64}$Zn and $^{16}$O + $^{64}$Zn have also been described.

K. P. Santhosh; V. Bobby Jose

2013-12-19

112

Interfacial and wetting properties of a binary point Yukawa fluid

NASA Astrophysics Data System (ADS)

We investigate the interfacial phase behavior of a binary fluid mixture composed of repulsive point Yukawa particles. Using a simple approximation for the Helmholtz free energy functional, which yields the random phase approximation for the pair direct correlation functions, we calculate the equilibrium fluid density profiles of the two species of particles adsorbed at a planar wall. We show that for a particular choice (repulsive exponential) of the wall potentials and the fluid pair-potential parameters, the Euler-Lagrange equations for the equilibrium fluid density profiles may be transformed into a single ordinary differential equation and the profiles obtained by a simple quadrature. For certain other choices of the fluid pair-potential parameters fluid-fluid phase separation of the bulk fluid is observed. We find that when such a mixture is exposed to a planar hard wall, the fluid exhibits complete wetting on the species 2 poor side of the binodal, i.e., we observe a thick film of fluid rich in species 2 adsorbed at the hard wall. The thickness of the wetting film grows logarithmically with the concentration difference between the fluid state point and the binodal and is proportional to the bulk correlation length of the intruding (wetting) fluid phase. However, for state points on the binodal that are further from the critical point, we find there is no thick wetting film. We determine the accompanying line of first-order (prewetting) surface phase transitions which separate a thin and thick adsorbed film. We show that for some other choices of repulsive wall potentials the prewetting line is still present, but its location and extent in the phase diagram is strongly dependent on the wall-fluid interaction parameters.

Hopkins, Paul; Archer, Andrew J.; Evans, Robert

2008-12-01

113

Interfacial and wetting properties of a binary point Yukawa fluid.

We investigate the interfacial phase behavior of a binary fluid mixture composed of repulsive point Yukawa particles. Using a simple approximation for the Helmholtz free energy functional, which yields the random phase approximation for the pair direct correlation functions, we calculate the equilibrium fluid density profiles of the two species of particles adsorbed at a planar wall. We show that for a particular choice (repulsive exponential) of the wall potentials and the fluid pair-potential parameters, the Euler-Lagrange equations for the equilibrium fluid density profiles may be transformed into a single ordinary differential equation and the profiles obtained by a simple quadrature. For certain other choices of the fluid pair-potential parameters fluid-fluid phase separation of the bulk fluid is observed. We find that when such a mixture is exposed to a planar hard wall, the fluid exhibits complete wetting on the species 2 poor side of the binodal, i.e., we observe a thick film of fluid rich in species 2 adsorbed at the hard wall. The thickness of the wetting film grows logarithmically with the concentration difference between the fluid state point and the binodal and is proportional to the bulk correlation length of the intruding (wetting) fluid phase. However, for state points on the binodal that are further from the critical point, we find there is no thick wetting film. We determine the accompanying line of first-order (prewetting) surface phase transitions which separate a thin and thick adsorbed film. We show that for some other choices of repulsive wall potentials the prewetting line is still present, but its location and extent in the phase diagram is strongly dependent on the wall-fluid interaction parameters. PMID:19063577

Hopkins, Paul; Archer, Andrew J; Evans, Robert

2008-12-01

114

Coulomb bubbles, though stable against monopole displacement, are unstable at least with respect to quadrupole and octupole distortions. We show that there exists a temperature at which the pressure of the vapor filling the bubble stabilizes all the radial modes. In extremely thin bubbles, the crispation modes become unstable due to the surface-surface interaction.

L. G. Moretto; K. Tso; G. J. Wozniak

1996-12-12

115

NSDL National Science Digital Library

CoulombÃÂs Essay on limiting statics stated that newly remoulded soil has no cohesion. Critical state soil mechanics agrees with this principle, here called CoulombÃÂs law. The Mohr-Coulomb equation wrongly interpreted strength data. The two components of peak strength really are friction and interlocking.

Schofield, Andrew N.

2008-09-23

116

Nonperturbative Effects on Seven-Brane Yukawa Couplings

We analyze nonperturbative corrections to the superpotential of seven-brane gauge theories on type IIB and F-theory warped Calabi-Yau compactifications. We show, in particular, that such corrections modify the holomorphic Yukawa couplings by an exponentially suppressed contribution, generically solving the Yukawa rank-one problem of certain F-theory local models. We provide explicit expressions for the nonperturbative correction to the seven-brane superpotential, and check that it is related to a noncommutative deformation to the tree-level superpotential via a Seiberg-Witten map.

Marchesano, Fernando [CERN PH-TH Division, CH-1211 Geneva (Switzerland); Martucci, Luca [ASC, LMU-Muenchen, Theresienstrasse 37, D-80333 Munich (Germany)

2010-06-11

117

Relativistic Coulomb Green's function in d dimensions

Using the operator method, we derive the Green's functions of the Dirac and Klein-Gordon equations in the Coulomb potential-Z{alpha}/r for an arbitrary space dimensionality d. Nonrelativistic and semiclassical asymptotic forms of these Green's functions are considered in detail.

Lee, R. N., E-mail: r.n.lee@inp.nsk.su; Milstein, A. I., E-mail: a.i.milstein@inp.nsk.su; Terekhov, I. S., E-mail: i.s.terekhov@inp.nsk.su [Budker Institute of Nuclear Physics (Russian Federation)

2011-08-15

118

(mercury.yukawa.kyoto-u.ac.jp)ssh Permission denied (publickey).

SSH Q&A (mercury.yukawa.kyoto-u.ac.jp)ssh Permission denied (publickey). (1) ID ID ID (2) ssh -i () ssh -i $HOME/.ssh/id_yitp_rsa (UID)@mercury.yukawa.kyoto-u.ac.jp (3) (1)(2) Permission denied support@yukawa.kyoto-u.ac.jp (mercury

Shimizu, Akira

119

Linear and quadratic static response functions and structure functions in Yukawa liquids.

We compute linear and quadratic static density response functions of three-dimensional Yukawa liquids by applying an external perturbation potential in molecular dynamics simulations. The response functions are also obtained from the equilibrium fluctuations (static structure factors) in the system via the fluctuation-dissipation theorems. The good agreement of the quadratic response functions, obtained in the two different ways, confirms the quadratic fluctuation-dissipation theorem. We also find that the three-point structure function may be factorizable into two-point structure functions, leading to a cluster representation of the equilibrium triplet correlation function. PMID:25215834

Magyar, Péter; Donkó, Zoltán; Kalman, Gabor J; Golden, Kenneth I

2014-08-01

120

Linear and quadratic static response functions and structure functions in Yukawa liquids

We compute linear and quadratic static density response functions of three-dimensional Yukawa liquids by applying an external perturbation potential in molecular dynamics simulations. The response functions are also obtained from the equilibrium fluctuations (static structure factors) in the system via the fluctuation-dissipation theorems. The good agreement of the quadratic response functions, obtained in the two different ways confirms the quadratic fluctuation-dissipation theorem. We also find that the three-point structure function may be factorizable into two-point structure functions, leading to a cluster representation of the equilibrium triplet correlation function.

Magyar, P; Kalman, G J; Golden, K I

2014-01-01

121

Test of the Stokes-Einstein relation in a two-dimensional Yukawa liquid

The Stokes-Einstein relation, relating the diffusion and viscosity coefficients D and eta, is tested in two dimensions. An equilibrium molecular-dynamics simulation was used with a Yukawa pair potential. Regimes are identified where motion is diffusive and D is meaningful. The Stokes-Einstein relation, D ~ kT, was found to be violated near the disordering transition; under these conditions collective particle motion exhibits dynamical heterogeneity. At slightly higher temperatures, however, the Stokes-Einstein relation is valid. These results may be testable in strongly-coupled dusty plasma experiments.

Bin Liu; J. Goree

2005-11-08

122

Two-dimensional Yukawa liquids: structure and collective excitations

NASA Astrophysics Data System (ADS)

The paper reports molecular dynamics (MD) simulations on two-dimensional, strongly-coulped Yukawa liquids. An effective coupling coefficient ?* for the liquid phase is identified; thermodynamic properties such as internal energy, pressure and compressibility, as well as longitudinal and transverse mode dispersions are analysed.

Hartmann, P.; Kalman, G. J.; Donkó, Z.

2006-04-01

123

Renormalization of Yukawa theory with a kernel in stochastic quantization

In this paper, renormalization of massive fermionic theory with a kernel, when fermions are coupled to bosons via Yukawa coupling is studied. It is shown that the theory is indeed renormalizable by proving that no new counterterms appear in the renormalized action.

Kapoor, A.K. (Services de Programmation de la Politique Scientifique, Brussels (Belgium)); Komoike, N.; Ohba, I.; Sandhya, R.; Tanaka, S. (Waseda Univ., Tokyo (Japan). Dept. of Physics)

1992-05-20

124

Casimir forces in a plasma: possible connections to Yukawa potentials

NASA Astrophysics Data System (ADS)

We present theoretical and numerical results for the screened Casimir effect between perfect metal surfaces in a plasma. We show how the Casimir effect in an electron-positron plasma can provide an important contribution to nuclear interactions. Our results suggest that there is a connection between Casimir forces and nucleon forces mediated by mesons. Correct nuclear energies and meson masses appear to emerge naturally from the screened Casimir-Lifshitz effect.

Ninham, Barry W.; Boström, Mathias; Persson, Clas; Brevik, Iver; Buhmann, Stefan Y.; Sernelius, Bo E.

2014-10-01

125

Casimir forces in a Plasma: Possible Connections to Yukawa Potentials

We present theoretical and numerical results for the screened Casimir effect between perfect metal surfaces in a plasma. We show how the Casimir effect in an electron-positron plasma can provide an important contribution to nuclear interactions. Our results suggest that there is a connection between Casimir forces and nucleon forces mediated by mesons. Correct nuclear energies and meson masses appear to emerge naturally from the screened Casimir-Lifshitz effect.

Barry W. Ninham; Mathias Boström; Clas Persson; Iver Brevik; Stefan Y. Buhmann; Bo E. Sernelius

2014-09-03

126

We study the coupling parameter dependence of the Higgs boson mass in a chirally invariant lattice Higgs-Yukawa model emulating the same Yukawa coupling structure as in the Higgs-fermion sector of the Standard Model. Eventually, the aim is to establish non-perturbative upper and lower Higgs boson mass bounds derived from first principles, in particular not relying on vacuum stability considerations for the latter case. Here, we present our lattice results for the lower Higgs boson mass bound at several values of the cutoff and compare them to corresponding analytical calculations based on the effective potential as obtained from lattice perturbation theory. Furthermore, we give a brief outlook towards the calculation of the upper Higgs boson mass bound.

P. Gerhold; K. Jansen

2009-02-24

127

Effects of supersymmetric threshold corrections on the Yukawa matrix unification

We present an updated analysis of the Yukawa matrix unification within the renormalizable Minimal Supersymmetric Standard Model. It is assumed that the soft terms are non-universal but flavour-diagonal in the super-CKM basis at the GUT scale. Trilinear Higgs-squark-squark A-terms can generate large threshold corrections to the Yukawa matrix $\\mathbf{Y}^d$ at the superpartner decoupling scale. In effect, the SU(5) boundary condition $\\mathbf{Y}^d=\\mathbf{Y}^{e\\,T}$ at the GUT scale can be satisfied. However, such large trilinear terms make the usual Higgs vacuum metastable (though long-lived). We broaden previous studies by including results from the first LHC phase, notably the measurement of the Higgs particle mass, as well as a quantitative investigation of flavour observables.

Iskrzynski, Mateusz

2014-01-01

128

Contribution of plasminos to the shear viscosity of a hot and dense Yukawa-Fermi gas

NASA Astrophysics Data System (ADS)

We determine the shear viscosity of a hot and dense Yukawa-Fermi gas, using the standard Green-Kubo relation, according to which the shear viscosity is given by the retarded correlator of the traceless part of the viscous energy-momentum tensor. We approximate this retarded correlator using a one-loop skeleton expansion, and express the bosonic and fermionic shear viscosities, ?b and ?f, in terms of bosonic and fermionic spectral widths, ?b and ?±. Here, the subscripts ± correspond to normal and collective (plasmino) excitations of fermions. We study, in particular, the effect of these excitations on thermal properties of ?f[?±]. To do this, we determine first the dependence of ?b and ?± on momentum p, temperature T, chemical potential ? and ?0?mb0/mf0, in a one-loop perturbative expansion in the orders of the Yukawa coupling. Here, mb0 and mf0 are T- and ?-independent bosonic and fermionic masses, respectively. We then numerically determine ?b[?b] and ?f[?±], and study their thermal properties. It turns out that whereas ?b and ?+ decrease with increasing T or ?, ?- increases with increasing T or ?. This behavior qualitatively changes by adding thermal corrections to mb0 and mf0, while the difference between ?+ and ?- keeps increasing with increasing T or ?. Moreover, ?b (?f) increases (decreases) with increasing T or ?. We show that the effect of plasminos on ?f becomes negligible with increasing (decreasing) T (?).

Sadooghi, N.; Taghinavaz, F.

2014-06-01

129

Coulomb force virtual space structures

Recently, several uses for intercraft Coulomb forces have been explored. Proposed applications have ranged from creating static formations of many spacecraft to steerable nanosat deployment systems. This paper considers the use of Coulomb forces for creating space structures. Unlike conventional space structures, these \\

Gordon Parker; Hanspeter Schaub; Arun Natarajan; Lyon King

2006-01-01

130

Yukawa unification: The good, the bad, and the ugly

We analyze some consequences of grand unification of the third-generation Yukawa couplings, in the context of the minimal supersymmetric standard model. We address two issues: the prediction of the top quark mass, and the generation of the top-bottom mass hierarchy through a hierarchy of Higgs vacuum expectation values. The top mass is strongly dependent on a certain ratio of superpartner masses. And the VEV hierarchy always entails some tuning of the GUT-scale parameters. We study the RG equations and their semi-analytic solutions, which exhibit several interesting features, such as a focusing effect for a large Yukawa coupling in the limit of certain symmetries and a correlation between the A terms (which contribute to b {yields} s{gamma}) and the gaugino masses. This study shows that non-universal soft-SUSY-breaking masses are favored (in particular for splitting the Higgs-doublets via D-terms and for allowing more natural scenarios of symmetry breaking), and hints at features desired in Yukawa-unified models. Several phenomenological implications are also revealed.

Rattazzi, R. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Sarid, U. [Stanford Univ., Stanford, CA (United States). Dept. of Physics; Hall, L.J. [Lawrence Berkeley Lab., CA (United States)

1993-05-01

131

Local logarithmic correlators as limits of Coulomb gas integrals

We will describe how logarithmic singularities arise as limits of Coulomb Gas integrals. Our approach will combine analytic properties of the time-like Liouville structure constants, together with the recursive formula of the Virasoro conformal blocks. Although the Coulomb Gas formalism forces a diagonal coupling between the chiral and antichiral sectors of the Conformal Field Theory (CFT), we present new results for the multi-screening integrals which are potentially interesting for applications to critical statistical systems described by Logarithmic CFTs. In particular our findings extend and complement previous results, derived with Coulomb Gas methods, at $c=0$ and $c=-2$.

Raoul Santachiara; Jacopo Viti

2013-11-08

132

Three-loop SM beta-functions for matrix Yukawa couplings

NASA Astrophysics Data System (ADS)

We present the extension of our previous results for three-loop Yukawa coupling beta-functions to the case of complex Yukawa matrices describing the flavour structure of the SM. The calculation is carried out in the context of unbroken phase of the SM with the help of the MINCER program in a general linear gauge and cross-checked by means of MATAD/BAMBA codes. In addition, ambiguities in Yukawa matrix beta-functions are studied.

Bednyakov, A. V.; Pikelner, A. F.; Velizhanin, V. N.

2014-10-01

133

Superdiffusion in two-dimensional Yukawa liquids.

Superdiffusion of two-dimensional (2D) liquids was studied using an equilibrium molecular dynamics simulation. At intermediate temperatures, the mean-squared displacement, probability distribution function (PDF), and velocity autocorrelation function (VACF) all indicate superdiffusion; the VACF has a long-time tail; and the PDF indicates no Lévy flights. These effects are predicted to occur in 2D dusty plasmas and other 2D liquids that can be modeled with a long-range repulsive potential. PMID:17358266

Liu, Bin; Goree, J

2007-01-01

134

Higgs mass bounds from renormalization flow for a simple Yukawa model

NASA Astrophysics Data System (ADS)

We study the functional renormalization group flow of a Higgs-Yukawa toy model mimicking the top-Higgs sector of the standard model. This approach allows for treating arbitrary bare couplings. For the class of standard bare potentials of ?4 type at a given ultraviolet cutoff, we show that a finite infrared Higgs mass range emerges naturally from the renormalization group flow itself. Higgs masses outside the resulting bounds cannot be connected to any conceivable set of bare parameters in this standard model ?4 class. By contrast, more general bare potentials allow us to diminish the lower bound considerably. We identify a simple renormalization group mechanism for this depletion of the lower bound. If this depletion is also active in the full standard model, Higgs masses smaller than the conventional infrared window do not necessarily require new physics at low scales or give rise to instability problems.

Gies, Holger; Gneiting, Clemens; Sondenheimer, René

2014-02-01

135

NASA Astrophysics Data System (ADS)

The radioactive isotope 107In was studied using sub-barrier Coulomb excitation at the REX-ISOLDE facility at CERN. Two ? rays were observed during the experiment, corresponding to the low-lying 11/2+ and 3/2- states. The reduced transition probability of the 11/2+ state was determined with the semiclassical Coulomb excitation code gosia2. The result is discussed in comparison to large-scale shell-model calculations, previous unified-model calculations, and earlier Coulomb excitation measurements in the odd-mass In isotopes.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Heyde, K.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2013-01-01

136

Coulomb Energy, Vortices, and Confinement

d on 25 Feb 2003 (v1), last revised 10 Apr 2003 (this version, v2))We estimate the Coulomb energy of static quarks from a Monte Carlo calculation of the correlator of timelike link variables in Coulomb gauge. We find, in agreement with Cucchieri and Zwanziger, that this energy grows linearly with distance at large quark separations. The corresponding string tension, however, is several times greater than the accepted asymptotic string tension, indicating that a state containing only static sources, with no constituent gluons, is not the lowest energy flux tube state. The Coulomb energy is also measured on thermalized lattices with center vortices removed by the de Forcrand-D'Elia procedure. We find that when vortices are removed, the Coulomb string tension vanishes.

Greensite, J.; Olejnik, S.

2003-02-25

137

Coulomb Friction Driving Brownian Motors

NASA Astrophysics Data System (ADS)

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.

Alessandro, Manacorda; Andrea, Puglisi; Alessandro, Sarracino

2014-10-01

138

Diffusion coefficient of three-dimensional Yukawa liquids

The purpose of this work is an investigation of the diffusion coefficient of the dust component in complex plasma. The computer simulation of the Yukawa liquids was made on the basis of the Langevin equation, which takes into account the influence of buffer plasma on the dust particles dynamics. The Green–Kubo relation was used to calculate the diffusion coefficient. Calculations of the diffusion coefficient for a wide range of the system parameters were performed. Using obtained numerical data, we constructed the interpolation formula for the diffusion coefficient. We also show that the interpolation formula correctly describes experimental data obtained under microgravity conditions.

Dzhumagulova, K. N.; Ramazanov, T. S.; Masheeva, R. U. [IETP, Al Farabi Kazakh National University, 71, al Farabi ave., Almaty 050040 (Kazakhstan)] [IETP, Al Farabi Kazakh National University, 71, al Farabi ave., Almaty 050040 (Kazakhstan)

2013-11-15

139

Melting in two-dimensional Yukawa systems: A Brownian dynamics simulation

NASA Astrophysics Data System (ADS)

We studied the melting behavior of two-dimensional colloidal crystals with a Yukawa pair potential by Brownian dynamics simulations. The melting follows the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) scenario with two continuous phase transitions and a middle hexatic phase. The two phase-transition points were accurately identified from the divergence of the translational and orientational susceptibilities. Configurational temperatures were employed to monitor the equilibrium of the overdamped system and the strongest temperature fluctuation was observed in the hexatic phase. The inherent structure obtained by rapid quenching exhibits three different behaviors in the solid, hexatic, and liquid phases. The measured core energy of the free dislocations, Ec = 7.81 +/- 0.91 kBT, is larger than the critical value of 2.84 kBT, which consistently supports the KTHNY melting scenario.

Qi, Wei-Kai; Wang, Ziren; Han, Yilong; Chen, Yong

2010-12-01

140

Empirical formulas for the fermion spectra and Yukawa matrices

NASA Astrophysics Data System (ADS)

We present empirical relations that connect the dimensionless ratios of low energy fermion masses for the charged lepton, up-type quark and down-type quark sectors and the CKM elements: leftlvert V_{us}rightrvert ? [ md/ms ]^{1/2} ? [ mu/mc ]^{1/4} ? 3 [ me/m_{?} ]^{1/2} and 1/2 leftlvert V_{cb}/V_{us}rightrvert ? [ ms3/m_{b2md} ]^{1/2} ? [ mc3/m_{t2mu} ]^{1/2} ? 1/9 [ m_{?}3/m_{tau2me} ]^{1/2}. Explaining these relations from first principles imposes strong constraints on the search for the theory of flavor. We present a simple set of normalized Yukawa matrices, with only two real parameters and one complex phase, which accounts with precision for these mass relations and for the CKM matrix elements and also suggests a simpler parametrization of the CKM matrix. The proposed Yukawa matrices accommodate the measured CP-violation, giving a particular relation between standard model CP-violating phases, ? = {Arg} [ 2 - mathrm {e}^{-mathrm i?} ]. According to this relation the measured value of ? is close to the maximum value that can be reached, ?_{max} = 30^{circ} for ? = 60^{circ}. Finally, the particular mass relations between the quark and charged lepton sectors find their simplest explanation in the context of grand unified models through the use of the Georgi-Jarlskog factor.

Ferrandis, J.

2004-12-01

141

LHC constraints on Yukawa unification in SO(10)

NASA Astrophysics Data System (ADS)

LHC constraints on the recently proposed SUSY SO(10) GUT model with top-bottom-tau Yukawa unification are investigated. In this model, various phenomenological constraints are in concord with the Yukawa unification thanks to the negative sign of ?, D-term splitting in the soft scalar masses and non-universal gaugino masses generated by a non-zero F -term in a 24-dimensional representation of SU(5) ? SO(10). After discussing the impact of the CP-odd Higgs boson mass bound on this model, we provide a detailed analysis of the recent direct SUSY searches performed by ATLAS and investigate the constraints on this SO(10) model. At 95% confidence level, the lower limit on the gluino mass is found to be 675 GeV. Assuming an integrated luminosity of 10 fb-1, this bound may be extended to 1.1 TeV if the right-handed down squark is lighter than about 1 TeV.

Badziak, Marcin; Sakurai, Kazuki

2012-02-01

142

Elementary Excitations of a Higgs-Yukawa System

NASA Astrophysics Data System (ADS)

This work investigates the physics of elementary excitations for the so-called relativistic quantum scalar plasma system, also known as the Higgs-Yukawa system. Following the Nemes-Piza-Kerman-Lin many-body procedure, the random-phase approximation (RPA) equations were obtained for this model by linearizing the time-dependent Hartree-Fock-Bogoliubov equations of motion around equilibrium. The resulting equations have a closed solution, from which the spectrum of excitation modes are studied. We show that the RPA oscillatory modes give the one-boson and two-fermion states of the theory. The results indicate the existence of bound states in certain regions in the phase diagram. Applying these results to recent Large Hadron Collider observations concerning the mass of the Higgs boson, we determine limits for the intensity of the coupling constant g of the Higgs-Yukawa model, in the RPA mean-field approximation, for three decay channels of the Higgs boson. Finally, we verify that, within our approximations, only Higgs bosons with masses larger than 190 GeV/c^2 can decay into top quarks.

Takano Natti, E. R.; de Toledo Piza, A. F. R.; Natti, P. L.; Lin, Chi-Yong

2013-06-01

143

Radiative Capture versus Coulomb Dissociation

Measurements of the Coulomb dissociation of 8B have been used to infer the rate of the inverse radiative proton capture on 7Be. The analysis is usually based on the assumptions that the two processes are related by detailed balance and described by E1 transitions. However, there are corrections to this relation. The Coulomb form factors for the two processes, for example, are not identical. There are also E2 transitions and higher-order effects in the Coulomb dissociation, and the nuclear induced breakup cannot always be ignored. While adding first-order E2 transitions enhances the decay energy spectrum, the other mechanisms cause a suppression at low relative energies. The net result may accidentally be close to the conventional first-order E1 calculation, but there are differences which cannot be ignored if accuracies of 10% or better are needed.

Esbensen, Henning [Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2006-03-13

144

Here we will discuss how the nonabelian Coulomb kernel exhibits confinement already at the mean field level. In the heavy quark limit residual interactions between heavy quarks and transverse gluons are spin dependent i.e., relativistic and can be calculated using the Foldy-Wouthuysen transformation. This makes the Coulomb gauge suitable for studying the nonrelativistic limit. Finally it is possible to use standard mean field techniques to define quasiparticle excitations, which, as we discuss below, have similar properties to what is usually assumed about constituent quarks in the light quark sector.

Adam P. Szczepaniak; Eric S. Swanson

2000-12-12

145

Renormalization in Coulomb gauge QCD

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.

Andrasi, A., E-mail: aandrasi@irb.hr ['Rudjer Boskovic' Institute, Zagreb (Croatia); Taylor, John C., E-mail: J.C.Taylor@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, University of Cambridge (United Kingdom)

2011-04-15

146

Boston University PhysLets: Coulomb's Law

NSDL National Science Digital Library

This interactive resource from the physics department at Boston University illustrates Coulomb's law. The simulation allows the user to graph the dependence of the Coulomb force on the distance between charges.

Duffy, Andrew

2010-06-07

147

Coulomb confinement from the Yang-Mills vacuum state in 2+1 dimensions

The Coulomb-gauge ghost propagator and the color-Coulomb potential are computed in an ensemble of configurations derived from our recently proposed Yang-Mills vacuum wave functional in 2+1 dimensions. The results are compared to the corresponding values obtained by standard Monte Carlo simulations in three Euclidean dimensions. The agreement is quite striking for the Coulomb-gauge ghost propagator. The color-Coulomb potential rises linearly at large distances, but its determination suffers from rather large statistical fluctuations, due to configurations with very low values of {mu}{sub 0}, the lowest eigenvalue of the Coulomb-gauge Faddeev-Popov operator. However, if one imposes cuts on the data, effectively leaving out configurations with very low {mu}{sub 0}, the agreement of the potential in both sets of configurations is again satisfactory, although the error bars grow systematically as the cutoff is eliminated.

Greensite, Jeff [Physics and Astronomy Department, San Francisco State University, San Francisco, California 94132 (United States); Olejnik, Stefan [Institute of Physics, Slovak Academy of Sciences, SK-845 11 Bratislava (Slovakia)

2010-04-01

148

A statistical model of quantum dot arrays with Coulomb coupling

We present a study of a statistical model of arrays of quantum dots, in which electrons are confined by semiconductor heterojunctions in all three dimensions, with Coulomb coupling. Our model describes repulsively interacting localized electrons whose number can vary with changes in chemical potential. By means of a Monte Carlo simulation, it is shown that, at low temperatures, some stable

Toshi-Kazu Suzuki; Kazumasa Nomoto; Ryuichi Ugajin; Ichiro Hase

1995-01-01

149

Relativistic Coulomb Green's function in $d$-dimensions

Using the operator method, the Green's functions of the Dirac and Klein-Gordon equations in the Coulomb potential $-Z\\alpha/r$ are derived for the arbitrary space dimensionality $d$. Nonrelativistic and quasiclassical asymptotics of these Green's functions are considered in detail.

R. N. Lee; A. I. Milstein; I. S. Terekhov

2011-01-28

150

Relativistic Coulomb Green's function in $d$-dimensions

Using the operator method, the Green's functions of the Dirac and Klein-Gordon equations in the Coulomb potential $-Z\\alpha/r$ are derived for the arbitrary space dimensionality $d$. Nonrelativistic and quasiclassical asymptotics of these Green's functions are considered in detail.

Lee, R N; Terekhov, I S

2011-01-01

151

Coulomb scattering for scalar field in Scr\\" odinger picture

The scattering of a charged scalar field on Coulomb potential on de Sitter space-time is studied using the solution of the free Klein-Gordon equation. We find that the scattering amplitude is independent of the choice of the picture and in addition the total energy is conserved in the scattering process.

Crucean Cosmin; Racoceanu Radu; Pop Adrian

2008-04-11

152

3D dust clouds (Yukawa Balls) in strongly coupled dusty plasmas

Three-dimensional finite systems of charged dust particles confined to concentric spherical shells in a dusty plasma, so-called 'Yukawa balls', have been studied with respect to their static and dynamic properties. Here, we review the charging of particles in a dusty plasma discharge by computer simulations and the respective particle arrangements. The normal mode spectrum of Yukawa balls is measured from the 3D thermal Brownian motion of the dust particles around their equilibrium positions.

Melzer, A.; Passvogel, M.; Miksch, T.; Ikkurthi, V. R.; Schneider, R. [Institute of Physics, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Block, D.; Piel, A. [IEAP, Christian-Albrechts-University Kiel, Olshausenstr. 40-60, 24098 Kiel (Germany)

2010-06-16

153

Higgs-Yukawa model in chirally-invariant lattice field theory

Non-perturbative numerical lattice studies of the Higgs-Yukawa sector of the standard model with exact chiral symmetry are reviewed. In particular, we discuss bounds on the Higgs boson mass at the standard model top quark mass, and in the presence of heavy fermions. We present a comprehensive study of the phase structure of the theory at weak and very strong values of the Yukawa coupling as well as at non-zero temperature.

John Bulava; Philipp Gerhold; Karl Jansen; Jim Kallarackal; Bastian Knippschild; C. -J. David Lin; Kei-Ichi Nagai; Attila Nagy; Kenji Ogawa

2012-10-05

154

Coulomb excitation and transfer reactions

NASA Astrophysics Data System (ADS)

Using the ?-spectrometer GASP and the PYRAMID array of position sensitive particle counters enabled improved nuclear structure studies employing direct reactions. Coulomb excitation of 232Th by 58Ni at a beam energy of 265 MeV was used to investigate multi-phonon surface vibrations. For 232Th a new band has been found which is interpreted as harmonic two-phonon octupole vibrational band with K ?=0 +. The system 110Pd + 52Cr was chosen to study the mechanism of multinucleon transfer at energies in the vicinity of the Coulomb barrier. It was possible to identify 10 different transfer channels by their characteristic ?-decay. The total excitation energy versus ?-multiplicity correlations for the most prominent even-even transfer channels show a ‘cold’ component which is a strong indication for correlated pair transfer. For the 2n and 2p channel this fraction is 30(4)%, respectively 16(8)%.

Gerl, J.; Bazzacco, D.; Elze, Th. W.; Happ, T.; Härtlein, T.; Korten, W.; Kröll, T.; Napoli, D.; Alvarez, C. Rossi; Schubert, R.; Vetter, K.; Wollersheim, H. J.

155

NASA Astrophysics Data System (ADS)

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton's "inverse-square law" of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. In this paper we study the entropic gravity correction to the gravitational force on the horizon of a black hole whose metric has been modified by a Yukawa term. We find that the gravitational radius of such a black hole is given in-terms of the Lambert function, and the entropic force introduces a extra term that depends on the square of the coupling constant ? of the Yukawa potential. In the case alpha equals zero we recover the Newtonian gravitational force on the horizon. In a first effort to obtain a relation between geometry and information, we calculate the Ricci scalar and through entropy we establish a relation to the number of information N where this is given in nats. Finally, we calculate a critical entropy value as well as a critical information number N c for which the curvature becomes identically zero which implies that the space becomes flat.

Haranas, Ioannis; Gkigkitzis, Ioannis

2013-09-01

156

On the contribution of plasminos to the shear viscosity of a hot and dense Yukawa-Fermi gas

We determine the shear viscosity of a hot and dense Yukawa-Fermi gas, using the standard Green-Kubo relation, according to which the shear viscosity is given by the retarded correlator of the traceless part of viscous energy-momentum tensor. We approximate this retarded correlator using a one-loop skeleton expansion, and express the bosonic and fermionic shear viscosities, $\\eta_{b}$ and $\\eta_{f}$, in terms of bosonic and fermionic spectral widths, $\\Gamma_{b}$ and $\\Gamma_{\\pm}$. Here, the subscripts $\\pm$ correspond to normal and collective (plasmino) excitations of fermions. We study, in particular, the effect of these excitations on thermal properties of $\\eta_{f}[\\Gamma_{\\pm}]$. To do this, we determine first the dependence of $\\Gamma_{b}$ and $\\Gamma_{\\pm}$ on momentum $p$, temperature $T$, chemical potential $\\mu$ and $\\xi_{0}\\equiv m_{b}^{0}/m_{f}^{0}$, in a one-loop perturbative expansion in the orders of the Yukawa coupling. Here, $m_{b}^{0}$ and $m_{f}^{0}$ are $T$ and $\\mu$ independent bosonic an...

Sadooghi, N

2014-01-01

157

NASA Astrophysics Data System (ADS)

Coulomb energies of the ^18Ne mirrors of the levels of ^18O vary considerably from state to state, an effect understood as arising from their different configurations. All the low-lying positive-parity states in these nuclei can be described in terms of two nucleons coupled to an ^16O core plus a collective component (most probably four-particle two-hole (4p-2h)). We have computed Coulomb energies using one such formulation(Lawson, Serduke and Fortune, Phys. Rev. C 14), 1245 (1976).. Two-particle energies arise from coupling a neutron to single-particle states of ^17O, and a proton to the mirror states of ^17F. For the 4p-2h component, we use the ^14O-^14C mass difference, plus a ph Coulomb term(Sherr and Bertsch, Phys. Rev. C 12), 1671 (1975).. Agreement is perhaps slightly better than another such attempt(Nero, Adelberger and Dietrich, Phys. Rev. C 24), 1864 (1981). using wave functions from Benson and Flowers.

Sherr, R.; Fortune, H. T.

1998-10-01

158

Effect of off-center positively charged Coulomb impurity on Dirac states in graphene magnetic dot

NASA Astrophysics Data System (ADS)

Using numerical diagonalization, we study the effect of the position of an off-center positively charged Coulomb impurity in a graphene magnetic dot, whose magnetic field profile is chosen as a Gaussian type. Numerical results show that the electron-hole symmetry is broken by the Coulomb potential and the originally zero energy states become nondegenerate and split into hole-like states. For the higher Landau levels shown, owing to the competition between the repulsive Coulomb potential and the magnetic confinement, the level orderings are reversed in the hole states at critical magnetic fields. Similar results are also obtained in the dot-size dependence of the low-lying spectra.

Lee, C. M.; Chan, K. S.

2014-05-01

159

Transport properties for an electroneutral Yukawa-type fluid in the MSA

NASA Astrophysics Data System (ADS)

In the framework of a linear response theory, in which Onsager’s continuity equations are combined with the Mean Spherical Approximation (MSA) from the theory of correlation functions in equilibrium, and using a Green’s function formalism, we consider the transport properties of electrolytes. The interaction between the ions in the electrolyte is represented by an intermolecular Yukawa potential which satisfies the electroneutrality condition. The model contains an adjustable parameter z which takes into account the effects of the solvent. Transport processes in an ionic solution are determined by two dominant forces: the relaxation and the electrophoretic forces; their contributions to the transport properties are calculated using the Fuoss-Onsager theory. We find the conductivity and the self-diffusion coefficient for a family of electrolytes using the linear response theory. The predictions of our model can be adjusted by means of the parameter z. The electrophoretic effect, due to the hydrodynamic interaction between the ions, is calculated using the Rotne-Prager tensor. Our theoretical results are in good agreement with experimental data for electrolytes 1-1, even for high concentrations. We applied this theory also to two unsymmetrical electrolytes, namely the aqueous solutions of MgCl2 and CaCl2, with results in good accord with experimental data.

Montes-Perez, J.; Herrera, J. N.

2014-01-01

160

Critical fluctuations and anomalous transport in soft Yukawa-Langevin systems

Simulation of a Langevin-dynamics model demonstrates emergence of critical fluctuations and anomalous grain transport which have been observed in experiments on ''soft'' quasi-two-dimensional dusty plasma clusters. Our model does not contain external drive or plasma interactions that serve to drive the system away from thermodynamic equilibrium. The grains are confined by an external potential, interact via static Yukawa forces, and are subject to stochastic heating and dissipation from neutrals. One remarkable feature is emergence of leptokurtic probability distributions of grain displacements {xi}({tau}) on time scales {tau}<{tau}{sub {delta}}, where {tau}{sub {delta}} is the time at which the standard deviation {sigma}({tau}){identical_to}<{xi}{sup 2}({tau})>{sup 1/2} approaches the mean intergrain distance {delta}. Others are development of humps in the distributions on multiples of {delta}, anomalous Hurst exponents, and transitions from leptokurtic toward Gaussian displacement distributions on time scales {tau}>{tau}{sub {delta}}. The latter is a signature of intermittency, here interpreted as a transition from bursty transport associated with hopping on intermediate time scales to vortical flows on longer time scales. These intermittency features are quantitatively modeled by a single-particle Ito-Langevin stochastic equation with a nonlinear drift term.

Ratynskaia, S. [Space and Plasma Physics, Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Regnoli, G. [Max-Planck-Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany); Space and Plasma Physics, Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Rypdal, K. [Department of Physics and Technology, University of Tromsoe, N-9037 Tromsoe (Norway); Klumov, B.; Morfill, G. [Max-Planck-Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany)

2009-10-15

161

Stabilizing the electroweak vacuum by higher dimensional operators in a Higgs-Yukawa model

The Higgs boson discovery at the LHC with a mass of approximately 126 GeV suggests, that the electroweak vacuum of the standard model may be metastable at very high energies. However, any new physics beyond the standard model can change this picture. We want to address this important question within a lattice Higgs-Yukawa model as the limit of the standard model (SM). In this framework we will probe the effect of a higher dimensional operator for which we take a $(\\phi^{\\dagger}\\phi)^3$-term. Such a term could easily originate as a remnant of physics beyond the SM at very large scales. As a first step we investigate the phase diagram of the model including such a $(\\phi^{\\dagger}\\phi)^3$ operator. Exploratory results suggest the existence of regions in parameter space where first order transitions turn to second order ones, indicating the existence of a tri-critical line. We will explore the phase structure and the consequences for the stability of the SM, both analytically by investigating the constraint effective potential in lattice perturbation theory, and by studying the system non-perturbatively using lattice simulations.

Prasad Hegde; Karl Jansen; C. -J. David Lin; Attila Nagy

2013-10-23

162

Coulomb blockade of small Pd clusters.

Single-electron tunneling through Au substrate-alkanethiol-Pd cluster-tip junctions is investigated with scanning tunneling spectroscopy. The measured I(V) curves reveal several characteristic features of the Coulomb blockade, namely, the presence of a Coulomb gap and a Coulomb staircase. By using the orthodox theory of single-electron tunneling, the capacitances and resistances of the double junction system as well as the fractional charge are extracted from the experimental data. PMID:16095380

Oncel, Nuri; Hallback, Ann-Sofie; Zandvliet, Harold J W; Speets, Emiel A; Ravoo, Bart Jan; Reinhoudt, David N; Poelsema, Bene

2005-07-22

163

Coulomb blockade of small Pd clusters

Single-electron tunneling through Au substrate-alkanethiol-Pd cluster-tip junctions is investigated with scanning tunneling spectroscopy. The measured I(V) curves reveal several characteristic features of the Coulomb blockade, namely, the presence of a Coulomb gap and a Coulomb staircase. By using the orthodox theory of single-electron tunneling, the capacitances and resistances of the double junction system as well as the fractional charge are

Nuri Oncel; Ann-Sofie Hallback; Harold J. W. Zandvliet; Emiel A. Speets; Bart Jan Ravoo; David N. Reinhoudt; Bene Poelsema

2005-01-01

164

Coulomb disorder in three-dimensional Dirac systems

NASA Astrophysics Data System (ADS)

In three-dimensional materials with a Dirac spectrum, weak short-ranged disorder is essentially irrelevant near the Dirac point. This is manifestly not the case for Coulomb disorder, where the long-ranged nature of the potential produced by charged impurities implies large fluctuations of the disorder potential even when impurities are sparse, and these fluctuations are screened by the formation of electron/hole puddles. In this paper, I present a theory of such nonlinear screening of Coulomb disorder in three-dimensional Dirac systems, and I derive the typical magnitude of the disorder potential, the corresponding density of states, and the size and density of electron/hole puddles. The resulting conductivity is also discussed.

Skinner, Brian

2014-08-01

165

Coulomb Impurity Screening in Graphene

NASA Astrophysics Data System (ADS)

I will discuss the vacuum polarization charge density around a Coulomb impurity with charge Z|e|. Perturbation theory in powers of Z? (where ?= e^2/vF is the effective coupling constant in graphene), shows that the polarization charge is localized at the impurity site. An exact calculation, based on the Green's function in a Coulomb field, leads to a non-perturbative result, valid to all orders in Z? [1]. Taking into account also electron-electron interactions in the Hartree approximation, we solve the problem self-consistently in the subcritical regime, where the impurity has an effective charge Zeff, determined by the localized induced charge. We find that an impurity with bare charge Z=1 remains subcritical, Zeff ?< 1/2, for any ?, while impurities with Z=2,3 and higher can become supercritical at certain values of ?. [1] I.S. Terekhov, A.I. Milstein, V.N. Kotov, and O.P. Sushkov, arXiv:0708.4263.

Kotov, Valeri

2008-03-01

166

Solution of two-body relativistic bound state equations with confining plus Coulomb interactions

NASA Technical Reports Server (NTRS)

Studies of meson spectroscopy have often employed a nonrelativistic Coulomb plus Linear Confining potential in position space. However, because the quarks in mesons move at an appreciable fraction of the speed of light, it is necessary to use a relativistic treatment of the bound state problem. Such a treatment is most easily carried out in momentum space. However, the position space Linear and Coulomb potentials lead to singular kernels in momentum space. Using a subtraction procedure we show how to remove these singularities exactly and thereby solve the Schroedinger equation in momentum space for all partial waves. Furthermore, we generalize the Linear and Coulomb potentials to relativistic kernels in four dimensional momentum space. Again we use a subtraction procedure to remove the relativistic singularities exactly for all partial waves. This enables us to solve three dimensional reductions of the Bethe-Salpeter equation. We solve six such equations for Coulomb plus Confining interactions for all partial waves.

Maung, Khin Maung; Kahana, David E.; Norbury, John W.

1992-01-01

167

NASA Astrophysics Data System (ADS)

We analyze the relation between Faddeev-Popov eigenmodes and gluon-momentum components in the Coulomb gauge using SU(3) lattice QCD. In the Coulomb gauge, the color-Coulomb energy is largely enhanced by near-zero Faddeev-Popov eigenmodes, which would lead to the confining potential. By the ultraviolet-momentum gluon cut, the color-Coulomb energy and the Faddeev-Popov spectrum are almost unchanged. In contrast to the ultraviolet insensitivity, the color-Coulomb energy and the Faddeev-Popov eigenmodes drastically change by infrared-momentum gluon cut. Without infrared gluons, the color-Coulomb energy tends to become nonconfining, and near-zero Faddeev-Popov eigenmodes vanish. We also investigate the full Faddeev-Popov eigenmodes, and find that infrared gluons widely influence both high and low Faddeev-Popov eigenmodes.

Iritani, Takumi; Suganuma, Hideo

2012-10-01

168

We analyze the relation between Faddeev-Popov eigenmodes and gluon-momentum components in the Coulomb gauge using SU(3) lattice QCD. In the Coulomb gauge, the color-Coulomb energy is largely enhanced by near-zero Faddeev-Popov eigenmodes, which would lead to the confining potential. By the ultraviolet-momentum gluon cut, the color-Coulomb energy and the Faddeev-Popov spectrum are almost unchanged. In contrast to the ultraviolet insensitivity, the color-Coulomb energy and the Faddeev-Popov eigenmodes drastically change by infrared-momentum gluon cut. Without infrared gluons, the color-Coulomb energy tends to become non-confining, and near-zero Faddeev-Popov eigenmodes vanish. We also investigate the full FP eigenmodes, and find that infrared gluons widely influence both high and low Faddeev-Popov eigenmodes.

Takumi Iritani; Hideo Suganuma

2012-04-30

169

Coulomb field of an accelerated charge: physical and mathematical aspects

The Maxwell field equations relative to a uniformly accelerated frame, and the variational principle from which they are obtained, are formulated in terms of the technique of geometrical gauge invariant potentials. They refer to the transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge invariant "2+2" decomposition is used to see how the Coulomb field of a charge, static in an accelerated frame, has properties that suggest features of electromagnetism which are different from those in an inertial frame. In particular, (1) an illustrative calculation shows that the Larmor radiation reaction equals the electrostatic attraction between the accelerated charge and the charge induced on the surface whose history is the event horizon, and (2) a spectral decomposition of the Coulomb potential in the accelerated frame suggests the possibility that the distortive effects of this charge on the Rindler vacuum are akin to those of a charge on a crystal lattice.

Francis J. Alexander; Ulrich H. Gerlach

1999-10-25

170

Quantum solution for the one-dimensional Coulomb problem

The one-dimensional hydrogen atom has been a much studied system with a wide range of applications. Since the pioneering work of Loudon [R. Loudon, Am. J. Phys. 27, 649 (1959).], a number of different features related to the nature of the eigenfunctions have been found. However, many of the claims made throughout the years in this regard are not correct--such as the existence of only odd eigenstates or of an infinite binding-energy ground state. We explicitly show that the one-dimensional hydrogen atom does not admit a ground state of infinite binding energy and that the one-dimensional Coulomb potential is not its own supersymmetric partner. Furthermore, we argue that at the root of many such false claims lies the omission of a superselection rule that effectively separates the right side from the left side of the singularity of the Coulomb potential.

Nunez-Yepez, H. N.; Salas-Brito, A. L.; Solis, Didier A. [Departamento de Fisica, Universidad Autonoma Metropolitana, Unidad Iztapalapa, Apartado Postal 55-534, Iztapalapa CP 09340 D. F. (Mexico); Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Apartado Postal 21-267, Coyoacan CP 04000 D. F. (Mexico); Facultad de Matematicas, Universidad Autonoma de Yucatan, Periferico Norte Tablaje C. 13615, Merida, Yucatan (Mexico)

2011-06-15

171

Upper Higgs boson mass bounds from a chirally invariant lattice Higgs-Yukawa model

We establish the cutoff-dependent upper Higgs boson mass bound by means of direct lattice computations in the framework of a chirally invariant lattice Higgs-Yukawa model emulating the same chiral Yukawa coupling structure as in the Higgs-fermion sector of the Standard Model. As expected from the triviality picture of the Higgs sector, we observe the upper mass bound to decrease with rising cutoff parameter $\\Lambda$. Moreover, the strength of the fermionic contribution to the upper mass bound is explored by comparing to the corresponding analysis in the pure $\\Phi^4$-theory.

P. Gerhold; K. Jansen

2010-02-23

172

PREFACE: Strongly Coupled Coulomb Systems

NASA Astrophysics Data System (ADS)

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 each area new results from theory, simulations and experiments were presented. In addition, a special symposium was held one evening to explore the questions on high-energy-density matter generated by intense heavy ion beams and to discuss the outlook for applications to industry. As this special issue illustrates, the field remains vibrant and challenging, being driven to a great extent by new experimental tools and access to new strongly coupled conditions. This is illustrated by the inclusion of developments in the areas of warm matter, dusty plasmas, condensed matter and ultra-cold plasmas. In total, 200 participants from 17 countries attended the conference, including 42 invited speakers. The individuals giving presentations at the conference, including invited plenary and topical talks and posters, were asked to contribute to this special issue and most have done so. We trust that this special issue will accurately record the contents of the conference, and provide a valuable resource for researchers in this rapidly evolving field. We would like to thank the members of the International Advisory Board and all members of the Programme Committee for their contributions to the conference. Of course, nothing would have been possible without the dedicated efforts of the Local Organizing Committee, in particular Igor Morozov and Valery Sultanov. We wish to thank the Russian Academy of Sciences, the Institute for High Energy Densities, the Institute of Problems of Chemical Physics, the Moscow Institute of Physics and Technology, the Ministry of Education and Science of the Russian Federation, the Russian Foundation for Basic Research, the Moscow Committee of Science and Technologies, the Russian Joint Stock Company `Unified Energy System of Russia', and The International Association for the Promotion of Co-operation with Scientists from the New Independent States (NIS) of the Former Soviet Union for sponsoring this conference.

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

2006-04-01

173

NASA Astrophysics Data System (ADS)

The ground state properties of 31Mg indicate a change of nuclear shape at N=19 with a deformed J=1/2 intruder state as a ground state, implying that 31Mg is part of the “island of inversion”. The collective properties of excited states were the subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam. De-excitation ?-rays were detected by the MINIBALL ?-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of 31Mg was extended. Spin and parity assignment of the 945 keV state yielded 5/2 and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that for the N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration.

Seidlitz, M.; Mücher, D.; Reiter, P.; Bildstein, V.; Blazhev, A.; Bree, N.; Bruyneel, B.; Cederkäll, J.; Clement, E.; Davinson, T.; Van Duppen, P.; Ekström, A.; Finke, F.; Fraile, L. M.; Geibel, K.; Gernhäuser, R.; Hess, H.; Holler, A.; Huyse, M.; Ivanov, O.; Jolie, J.; Kalkühler, M.; Kotthaus, T.; Krücken, R.; Lutter, R.; Piselli, E.; Scheit, H.; Stefanescu, I.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.

2011-06-01

174

Probing Minicharged Particles with Tests of Coulomb's Law

Minicharged particles arise in many extensions of the standard model. Their contribution to the vacuum polarization modifies Coulomb's law via the Uehling potential. In this Letter, we argue that tests for electromagnetic fifth forces can therefore be a sensitive probe of minicharged particles. In the low mass range < or approx. mueV existing constraints from Cavendish type experiments provide the best model-independent bounds on minicharged particles.

Jaeckel, Joerg [Institute for Particle Physics Phenomenology, Durham University, Durham DH1 3LE (United Kingdom)

2009-08-21

175

Comparison of COULOMB-2, NASCAP-2k and SPIS codes for geostationary spacecrafts charging

NASA Astrophysics Data System (ADS)

In developing of international standards for spacecraft charging, it is necessary to compare results of spacecraft charging modeling obtained with various models. In the paper, electrical potentials for spacecraft 3D models were calculated with COULOMB-2, NASCAP-2k [1] and SPIS [2] software, and the comparison of obtained values was performed. To compare COULOMB-2 and NASCAP-2k codes we used a 3D geometrical model of a spacecraft given in [1]. Parameters of spacecraft surface materials were taken from [1], too. For COULOMB-2 and SPIS cross validation, we carried out calculations with SPIS code through SPENVIS web-interface and with COULOMB-2 software for a spacecraft geometrical model given in SPIS test examples [2]. In both cases, we calculated distributions of electric potentials on the spacecraft surface and visualized the obtained distributions with color code. Pictures of the surface potentials distribution calculated with COULOMB-2 and SPIS software are in good qualitative agreement. Absolute values of surface potentials calculated with these codes for different plasma conditions, are close enough. Pictures of the surface potentials distribution calculated for the spacecraft model [1] with COULOMB-2 software completely correspond to actual understanding of physical mechanisms of differential spacecraft surface charging. In this case, we compared only calculated values of the surface potential for the same space plasma conditions because the potential distributions on the spacecraft surface are absent in [1]. For all the plasma conditions considered, COULOMB-2 model gives higher absolute values of negative potential, than NASCAP-2k model. Differences in these values reach 2-3 kV. The possible explanations of the divergences indicated above are distinctions in calculation procedures of primary plasma currents and secondary emission currents. References 1. Ferguson D.?., Wimberly S.C. 51st AIAA Aerospace Science Meeting 2013 (AIAA 2013-0810). 2. http://dev.spis.org/projects/spine/home/spis

Novikov, Lev; Makletsov, Andrei; Sinolits, Vadim

176

On the contribution of plasminos to the shear viscosity of a hot and dense Yukawa-Fermi gas

We determine the shear viscosity of a hot and dense Yukawa-Fermi gas, using the standard Green-Kubo relation, according to which the shear viscosity is given by the retarded correlator of the traceless part of viscous energy-momentum tensor. We approximate this retarded correlator using a one-loop skeleton expansion, and express the bosonic and fermionic shear viscosities, $\\eta_{b}$ and $\\eta_{f}$, in terms of bosonic and fermionic spectral widths, $\\Gamma_{b}$ and $\\Gamma_{\\pm}$. Here, the subscripts $\\pm$ correspond to normal and collective (plasmino) excitations of fermions. We study, in particular, the effect of these excitations on thermal properties of $\\eta_{f}[\\Gamma_{\\pm}]$. To do this, we determine first the dependence of $\\Gamma_{b}$ and $\\Gamma_{\\pm}$ on momentum $p$, temperature $T$, chemical potential $\\mu$ and $\\xi_{0}\\equiv m_{b}^{0}/m_{f}^{0}$, in a one-loop perturbative expansion in the orders of the Yukawa coupling. Here, $m_{b}^{0}$ and $m_{f}^{0}$ are $T$ and $\\mu$ independent bosonic and fermionic masses, respectively. We then numerically determine $\\eta_{b}[\\Gamma_{b}]$ and $\\eta_{f}[\\Gamma_{\\pm}]$, and study their thermal properties. It turns out that whereas $\\Gamma_{b}$ and $\\Gamma_{+}$ decrease with increasing $T$ or $\\mu$, $\\Gamma_{-}$ increases with increasing $T$ or $\\mu$. This behavior qualitatively changes by adding thermal corrections to $m_{b}^{0}$ and $m_{f}^{0}$, while the difference between $\\Gamma_{+}$ and $\\Gamma_{-}$ keeps increasing with increasing $T$ or $\\mu$. Moreover, $\\eta_{b}$ ($\\eta_{f}$) increases (decreases) with increasing $T$ or $\\mu$. We show that the effect of plasminos on $\\eta_{f}$ becomes negligible with increasing (decreasing) $T$ ($\\mu$).

N. Sadooghi; F. Taghinavaz

2014-04-06

177

Extended Kepler-Coulomb quantum superintegrable systems in 3 dimensions

The quantum Kepler-Coulomb system in 3 dimensions is well known to be 2nd order superintegrable, with a symmetry algebra that closes polynomially under commutators. This polynomial closure is also typical for 2nd order superintegrable systems in 2D and for 2nd order systems in 3D with nondegenerate (4-parameter) potentials. However the degenerate 3-parameter potential for the 3D Kepler-Coulomb system (also 2nd order superintegrable) is an exception, as its symmetry algebra doesn't close polynomially. The 3D 4-parameter potential for the extended Kepler-Coulomb system is not even 2nd order superintegrable, but Verrier and Evans (2008) showed it was 4th order superintegrable, and Tanoudis and Daskaloyannis (2011) showed that, if a 2nd 4th order symmetry is added to the generators, the symmetry algebra closes polynomially. Here, based on the Tremblay, Turbiner and Winternitz construction, we consider an infinite class of quantum extended Kepler-Coulomb 3 and 4-parameter systems indexed by a pair of rational numbers (k_1,k_2) and reducing to the usual systems when k_1=k_2=1. We show these systems to be superintegrable of arbitrarily high order and determine the structure of their symmetry algebras. We demonstrate that the symmetry algebras close algebraically; only for systems admitting extra discrete symmetries is polynomial closure achieved. Underlying the structure theory is the existence of raising and lowering operators, not themselves symmetry operators or even defined independent of basis, that can be employed to construct the symmetry operators and their structure relations.

E. G. Kalnins; J. M. Kress; W. Miller Jr

2012-10-30

178

Yukawa couplings and fermion mass structure in F-theory GUTs

NASA Astrophysics Data System (ADS)

The calculation of Yukawa couplings in F-theory GUTs is developed. The method is applied to the top and bottom Yukawa couplings in an SU(5)? model of fermion masses based on family symmetries coming from the SU(5) factor in the underlying E(8) theory. The remaining Yukawa couplings involving the light quark generations are determined by the Froggatt Nielsen non-renormalisable terms generated by heavy messenger states. We extend the calculation of Yukawa couplings to include massive states and estimate the full up and down quark mass matrices in the SU(5) model. We discuss the new features of the resulting structure compared to what is usually assumed for Abelian family symmetry models and show how the model can give a realistic quark mass matrix structure. We extend the analysis to the neutrino sector masses and mixing where we find that tri-bi-maximal mixing is readily accommodated. Finally we discuss mechanisms for splitting the degeneracy between the charged leptons and the down quarks and the doublet triplet splitting in the Higgs sector.

Leontaris, G. K.; Ross, G. G.

2011-02-01

179

Yukawa-Field Approximation of Electrostatic Free Energy and Dielectric Boundary Force

free energy of a molecular sol- vation system with an implicit or continuum solvent is constructed, electrostatic free energy, Yukawa-field approxima- tion, shape derivative. 1 Introduction Implicit-solvent (or is a free-energy functional of all possible solute- solvent interfaces, or dielectric boundaries

Li, Bo

180

SU(5) and SO(10) models from F-theory with natural Yukawa couplings

We construct the SU(5) and SO(10) models from F-theory. Turning on the U(1) fluxes, we can break the SU(5) gauge symmetry down to the standard model (SM) gauge symmetry, and break the SO(10) gauge symmetry down to the SU(3){sub C}xSU(2){sub L}xSU(2){sub R}xU(1){sub B-L} gauge symmetry. In particular, all the SM fermion Yukawa couplings preserve the enhanced U(1){sub a}xU(1){sub b} gauge or global symmetries at the triple intersections of the SM fermion and Higgs curves. And the SM fermion masses and mixings can be generated in the presence of background fluxes. In our models, the doublet-triplet splitting problem can be solved naturally. The additional vectorlike particles can obtain heavy masses via the instanton effects or Higgs mechanism and then decouple at the high scale. The SM gauge couplings at the string scale, which are split due to the U(1) flux effects, can be explained by considering heavy threshold corrections from the extra vectorlike particles. Moreover, in the SU(5) model, we have the Yukawa coupling unification for the bottom quark and tau lepton. In the SO(10) models, we have the Yukawa coupling unification for the top and bottom quarks, and the Yukawa coupling unification for the tau lepton and tau neutrino.

Li Tianjun [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China) and George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, Texas 77843 (United States)

2010-03-15

181

The thermodynamic properties of a binary Yukawa mixture are calculated within the mean spherical approximation (MSA) using both the energy and compressibility routes. Two types of binary mixtures are considered: (a) a mixture, denoted by M1, that exhibits a tendency to homocoordination; and (b) another, denoted by M2, that exhibits a tendency to heterocoordination. Also, two types of calculations are

D. J. Gonzalez; L. E. Gonzalez; M. Silbert

1990-01-01

182

Vapor-liquid surface tension of strong short-range Yukawa fluid

The thermodynamic properties of strong short-range attractive Yukawa fluids, k=10, 9, 8, and 7, are determined by combining the slab technique with the standard and the replica exchange Monte Carlo (REMC) methods. A good agreement was found among the coexistence curves of these systems calculated by REMC and those previously reported in the literature. However, REMC allows exploring the coexistence

G. Odriozola; M. Bárcenas; P. Orea

2011-01-01

183

Coulomb impurity problem of graphene in magnetic fields

Analytical solutions of the Coulomb impurity problem of graphene in the absence of a magnetic field show that when the dimensionless strength of the Coulomb potential $g$ reaches a critical value the solutions become supercritical with imaginary eigenenergies. Application of a magnetic field is a singular perturbation, and no analytical solutions are known except at a denumerably infinite set of magnetic fields. We find solutions of this problem by numerical diagonalization of large Hamiltonian matrices. Solutions are qualitatively different from those of zero magnetic field. All energies are discrete and no complex energies allowed. We have computed the finite-size scaling function of the probability density containing s-wave component of Dirac wavefunctions. This function depends on the coupling constant, regularization parameter, and the gap. In the limit of vanishing regularization parameter our findings are consistent with the expected values exponent $\

Kim, S C

2014-01-01

184

Effect of Coulomb Screening Length on Nuclear Pasta Simulations

We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semi-classical molecular dynamics model, studying isospin symmetric matter at sub-saturation densities and low temperatures. The electrostatic interaction between protons interaction is included in the form of a screened Coulomb potential in the spirit of the Thomas-Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the non-homogeneous nuclear structures known as "nuclear pasta". As the screening length increases, we can a transition from a one-per-cell pasta regime (due exclusively to finite size effects) to a more appealing multiple pasta per simulation box. This shows qualitative difference in the structure of neutron star matter at low temperatures, and therefore, special caution should be taken when the screening length is estimated for numerical simulations.

P. N. Alcain; P. A. Giménez Molinelli; J. I. Nichols; C. O. Dorso

2013-11-22

185

Reaction mechanisms involving weakly bound Li6 and Bi209 at energies near the Coulomb barrier

NASA Astrophysics Data System (ADS)

The elastic, inelastic, and transfer cross sections are measured for the 6Li+209Bi reaction at energies around the Coulomb barrier. The optical model analysis of elastic scattering shows a breakup threshold anomaly in the energy dependence of the real and imaginary potentials. The observed energy dependence is found to be consistent with the dynamic polarization potential obtained from the coupled-channels calculations that explain the above measured reaction channels simultaneously. A comparison of different reaction probabilities reveals that the relative contribution of breakup starts increasing at energies below the Coulomb barrier, in contrast to the behavior of other reaction channels, which get closed as energy is lowered. The large probability of projectile breakup at sub-Coulomb energies leads to the observation of a nonzero imaginary potential even at Elab?0.8VB.

Santra, S.; Kailas, S.; Ramachandran, K.; Parkar, V. V.; Jha, V.; Roy, B. J.; Shukla, P.

2011-03-01

186

The Higgs boson resonance width from a chiral Higgs-Yukawa model on the lattice

The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for quarks, leptons and the weak gauge bosons. We use a 4-dimensional Euclidean lattice formulation of the Higgs-Yukawa sector of the electroweak model to compute physical quantities in the path integral approach which is evaluated by means of Monte Carlo simulations thus allowing for fully non perturbative calculations. The chiral symmetry of the model is incorporated by using the Neuberger overlap Dirac operator. The here considered Higgs-Yukawa model does not involve the weak gauge bosons and furthermore, only a degenerate doublet of top- and bottom quarks are incorporated. The goal of this work is to study the resonance properties of the Higgs boson and its sensitivity to the strength of the quartic self coupling.

Philipp Gerhold; Karl Jansen; Jim Kallarackal

2011-11-21

187

Monte Carlo Study of the Yukawa Coupled Two Spin Ising Model

We consider a particular 4 state spin system composed of two Ising spins (~$s_x, \\; \\sigma_x$~) with independent hopping parameters $\\kappa_1, \\kappa_2$, coupled by a bilinear Yukawa term, $y s_x \\sigma_x$. The Yukawa term is solely responsible for breaking the global $ Z_2 \\times Z_2$ symmetry down to $Z_2$. This model is intended as an illustration of general coupled Higgs system where scalars can arise both as composite and elementary excitations. For the Ising example in 2d, we give convincing numerical evidence of the universality of the two spin system with the one spin Ising model, by Monte Carlo simulations and finite scaling analysis . We also show that as we approach the phase transition, universality arises by a separation of low mass spin waves from an extra set of spin waves with an energy gap that diverges as the correlations length diverges

R. Brower; K. Orginos; Y. Shen; C-I Tan

1995-07-13

188

Using classical molecular dynamics (MD) simulations, we report on the development and propagation of a nonlinear heat front in parallel shear flows of a strongly coupled Yukawa liquid. At a given coupling strength, a subsonic shear profile is superposed on an equilibrated Yukawa liquid and Kelvin Helmholtz (KH) instability is observed. Coherent vortices are seen to emerge towards the nonlinear regime of the instability. It is seen that while inverse cascade leads to a continuous transfer of flow energy towards the largest scales, there is also a simultaneous transfer of flow energy into the thermal velocities of grains at the smallest scale. The latter is an effect of velocity shear and thus leads to the generation of a nonlinear heat front. In the linear regime, the heat front is seen to propagate at speed much lesser than the adiabatic sound speed of the liquid. Spatio-temporal growth of this heat front occurs concurrently with the inverse cascade of KH modes.

Ashwin, J.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar 382428, Gujarat (India)

2011-08-15

189

Application of the proximity force approximation to gravitational and Yukawa-type forces

We apply the proximity force approximation, which is widely used for the calculation of the Casimir force between bodies with nonplanar boundary surfaces, to gravitational and Yukawa-type interactions. It is shown that for the gravitational force in a sphere-plate configuration the general formulation of the proximity force approximation is well applicable. For a Yukawa-type interaction we demonstrate the validity of both the general formulation of the proximity force approximation and a simple mapping between the sphere-plate and plate-plate configurations. The claims to the contrary in some recent literature are thus incorrect. Our results justify the constraints on the parameters of non-Newtonian gravity previously obtained from the indirect dynamic measurements of the Casimir pressure.

Decca, R. S. [Department of Physics, Indiana University--Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States); Fischbach, E. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Klimchitskaya, G. L. [North-West Technical University, Millionnaya Street 5, St. Petersburg, 191065 (Russian Federation); Krause, D. E. [Physics Department, Wabash College, Crawfordsville, Indiana 47933 (United States); Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Lopez, D. [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Mostepanenko, V. M. [Noncommercial Partnership 'Scientific Instruments', Tverskaya Street 11, Moscow, 103905 (Russian Federation)

2009-06-15

190

Self-adjoint extensions of Coulomb systems in 1, 2 and 3 dimensions

NASA Astrophysics Data System (ADS)

We study the nonrelativistic quantum Coulomb hamiltonian (i.e., inverse of distance potential) in Rn, n=1,2,3. We characterize their self-adjoint extensions and, in the unidimensional case, present a discussion of controversies in the literature, particularly the question of the permeability of the origin. Potentials given by fundamental solutions of Laplace equation are also briefly considered.

de Oliveira, César R.; Verri, Alessandra A.

2009-02-01

191

Higgs boson mass and sparticle spectroscopy in Yukawa unified SUSY SO(10)

We employ third family Yukawa unification, predicted by simple supersymmetric SO(10) models, to estimate the lightest MSSM Higgs boson mass. For {mu} > 0 (or {mu} < 0) and m{sub t} = 173.1GeV, the Higgs mass is estimated to lie close to 123-124 GeV. The theoretical uncertainty in this estimate is {+-}3 GeV. We highlight some LHC testable benchmark points which also display the presence of neutralino-stau coannihilation channel.

Shafi, Qaisar [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

2012-07-27

192

Higgs mass bounds from a chirally invariant lattice Higgs-Yukawa model with overlap fermions

We study the parameter dependence of the Higgs mass in a chirally invariant lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model. Eventually, the aim is to establish upper and lower Higgs mass bounds. Here we present our preliminary results on the lower Higgs mass bound at several selected values for the cutoff and give a brief outlook towards the upper Higgs mass bound.

Philipp Gerhold; Karl Jansen; Jim Kallarackal

2008-10-24

193

Coulomb interaction effects on the Majorana states in quantum wires.

The stability of the Majorana modes in the presence of a repulsive interaction is studied in the standard semiconductor wire-metallic superconductor configuration. The effects of short-range Coulomb interaction, which is incorporated using a purely repulsive ?-function to model the strong screening effect due to the presence of the superconductor, are determined within a Hartree-Fock approximation of the effective Bogoliubov-De Gennes Hamiltonian that describes the low-energy physics of the wire. Through a numerical diagonalization procedure we obtain interaction corrections to the single particle eigenstates and calculate the extended topological phase diagram in terms of the chemical potential and the Zeeman energy. We find that, for a fixed Zeeman energy, the interaction shifts the phase boundaries to a higher chemical potential, whereas for a fixed chemical potential this shift can occur either at lower or higher Zeeman energies. These effects can be interpreted as a renormalization of the g-factor due to the interaction. The minimum Zeeman energy needed to realize Majorana fermions decreases with the increasing strength of the Coulomb repulsion. Furthermore, we find that in wires with multi-band occupancy this effect can be enhanced by increasing the chemical potential, i.e. by occupying higher energy bands. PMID:24722427

Manolescu, A; Marinescu, D C; Stanescu, T D

2014-04-30

194

Supersymmetric Grand Unified Theories: Two Loop Evolution of Gauge and Yukawa Couplings

We make a numerical study of gauge and Yukawa unification in supersymmetric grand unified models and examine the quantitative implications of fermion mass ans\\"{a}tze at the grand unified scale. Integrating the renormalization group equations with $\\alpha _1(M_Z)$ and $\\alpha _2(M_Z)$ as inputs, we find $\\alpha _3(M_Z)\\simeq 0.111 (0.122)$ for $M_{SUSY}^{}=m_t$ and $\\alpha _3(M_Z)\\simeq 0.106 (0.116)$ for $M_{SUSY}^{}=1$ TeV at one-loop (two-loop) order. Including $b$ and $\\tau $ Yukawa couplings in the evolution, we find an upper limit $m_t\\ltap 200$ GeV from Yukawa unification. For given $m_t\\ltap 175$ GeV, there are two solutions for $\\beta$, one with $\\tan \\beta > m_t/m_b$, and one with $\\sin \\beta \\simeq 0.78(m_t/150\\;{\\rm GeV})$. Taking a popular ansatz for the mass matrices at the unified scale, we obtain a lower limit on the top quark mass of $m_t\\gtap 150 (115)$ GeV for $\\alpha _3(M_Z)=0.11 (0.12)$ and an upper limit on the supersymmetry parameter $\\tan \\beta \\ltap 50$ if $\\alpha _3(M_Z)=0.11$. The evolution of the quark mixing matrix elements is also evaluated.

V. Barger; M. S. Berger; P. Ohmann

1992-09-14

195

Beyond the God-particle at the Tevatron: detecting gluinos from Yukawa-unified SUSY

Simple SUSY GUT models based on the gauge group SO(10) require t-b-\\tau Yukawa coupling unification, in addition to gauge coupling and matter unification. The Yukawa coupling unification places strong constraints on the expected superparticle mass spectrum, with scalar masses \\sim 10 TeV while gluino masses are much lighter: in the 300--500 GeV range. The very heavy squarks suppress negative interference in the q\\bar{q}\\to\\tg\\tg cross section, leading to a large enhancement in production rates. The gluinos decay almost always via three-body modes into a pair of b-quarks, so we expect at least four b-jets per signal event. We investigate the capability of Fermilab Tevatron collider experiments to detect gluino pair production in Yukawa-unified SUSY. By requiring events with large missing E_T and \\ge 2 or 3 tagged b-jets, we find a 5\\sigma reach in excess of m_{\\tg}\\sim 400 GeV for 5 fb^{-1} of data. This range in m_{\\tg} is much further than the conventional Tevatron SUSY reach, and should cut a significant sw...

Baer, Howard; Sekmen, Sezen; Summy, Heaya

2009-01-01

196

NASA Astrophysics Data System (ADS)

A practical method of solving cutoff Coulomb problems of two-cluster systems in momentum space is given. When a sharply cut-off Coulomb force with a cutoff radius ? is introduced at the level of constituent particles, the two-cluster direct potential of the Coulomb force becomes in general a local screened Coulomb potential. The asymptotic Hamiltonian yields two types of asymptotic waves; one is an approximate Coulomb wave with ? in the middle-range region, and the other a free (no-Coulomb) wave in the longest-range region. The constant Wronskians of this Hamiltonian can be calculated in either region. We can evaluate the Coulomb-modified nuclear phase shifts for the screened Coulomb problem using the matching condition proposed by Vincent and Phatak for the sharply cut-off Coulomb problem. We apply this method first to an exactly solvable model of the ? ? scattering with the Ali-Bodmer potential and confirm that a complete solution is obtained with a finite ?. The stability of nuclear phase shifts with respect to the change in ? within some appropriate range is demonstrated in the ? ? resonating-group method (RGM) calculation using the Minnesota three-range force. An application to the pd elastic scattering is also discussed.

Fujiwara, Y.; Fukukawa, K.

2012-08-01

197

NASA Astrophysics Data System (ADS)

Understanding the mechanisms of clustering in colloids, nanoparticles, and proteins is of significant interest in material science and both chemical and pharmaceutical industries. Recently, using an integral equation theory formalism, Bomont et al. [J. Chem. Phys. 132, 184508 (2010)] studied theoretically the temperature dependence, at a fixed density, of the cluster formation in systems where particles interact with a hard-core double Yukawa potential composed of a short-range attraction and a long-range repulsion. In this paper, we provide evidence that the low-q peak in the static structure factor, frequently associated with the formation of clusters, is a common behavior in systems with competing interactions. In particular, we demonstrate that, based on a thermodynamic self-consistency criterion, accurate structural functions are obtained for different choices of closure relations. Moreover, we explore the dependence of the low-q peak on the particle number density, temperature, and potential parameters. Our findings indicate that enforcing thermodynamic self-consistency is the key factor to calculate both thermodynamic properties and static structure factors, including the low-q behavior, for colloidal dispersions with both attractive and repulsive interactions. Additionally, a simple analysis of the mean number of neighboring particles provides a qualitative description of some of the cluster features.

Kim, Jung Min; Castañeda-Priego, Ramón; Liu, Yun; Wagner, Norman J.

2011-02-01

198

Coulombic effect and renormalization in nuclear pairing

We investigate the effects of the Coulomb force on the nuclear pairing properties by performing the Gogny Hartree-Fock-Bogolyubov calculations for the N=20, 28, 50, 82, and 126 nuclei. The Coulomb force reduces the proton pair energy and the even-odd mass difference by about 25%, except for nuclei at and around the proton shell or subshell closure. We then propose a renormalization scheme via a reduction factor {gamma}{sub p} for the proton pairing channel. It is found that a single value {gamma}{sub p}=0.90 accounts well for the Coulombic effect for nuclei covering a wide range of the mass number and the neutron excess, including the nuclei around the shell or subshell closure.

Nakada, H.; Yamagami, M. [Department of Physics, Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage, Chiba 263-8522 (Japan); Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580 (Japan)

2011-03-15

199

"Safe" Coulomb excitation of 30Mg.

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion." PMID:15904283

Niedermaier, O; Scheit, H; Bildstein, V; Boie, H; Fitting, J; von Hahn, R; Köck, F; Lauer, M; Pal, U K; Podlech, H; Repnow, R; Schwalm, D; Alvarez, C; Ames, F; Bollen, G; Emhofer, S; Habs, D; Kester, O; Lutter, R; Rudolph, K; Pasini, M; Thirolf, P G; Wolf, B H; Eberth, J; Gersch, G; Hess, H; Reiter, P; Thelen, O; Warr, N; Weisshaar, D; Aksouh, F; Van den Bergh, P; Van Duppen, P; Huyse, M; Ivanov, O; Mayet, P; Van de Walle, J; Aystö, J; Butler, P A; Cederkäll, J; Delahaye, P; Fynbo, H O U; Fraile, L M; Forstner, O; Franchoo, S; Köster, U; Nilsson, T; Oinonen, M; Sieber, T; Wenander, F; Pantea, M; Richter, A; Schrieder, G; Simon, H; Behrens, T; Gernhäuser, R; Kröll, T; Krücken, R; Münch, M; Davinson, T; Gerl, J; Huber, G; Hurst, A; Iwanicki, J; Jonson, B; Lieb, P; Liljeby, L; Schempp, A; Scherillo, A; Schmidt, P; Walter, G

2005-05-01

200

'Safe' Coulomb Excitation of {sup 30}Mg

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient {gamma} spectrometer MINIBALL. Using {sup 30}Mg ions accelerated to an energy of 2.25 MeV/u together with a thin {sup nat}Ni target, Coulomb excitation of the first excited 2{sup +} states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation {gamma}-ray yields the B(E2;0{sub gs}{sup +}{yields}2{sub 1}{sup +}) value of {sup 30}Mg was determined to be 241(31)e{sup 2} fm{sup 4}. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope {sup 30}Mg resides outside the 'island of inversion'.

Niedermaier, O.; Scheit, H.; Bildstein, V.; Boie, H.; Fitting, J.; Hahn, R. von; Koeck, F.; Lauer, M.; Pal, U.K.; Podlech, H.; Repnow, R.; Schwalm, D. [Max-Planck-Insitut fuer Kernphysik, Heidelberg (Germany); Alvarez, C.; Ames, F.; Bollen, G.; Emhofer, S.; Habs, D.; Kester, O.; Lutter, R.; Rudolph, K. [Ludwig-Maximilians-Universitaet, Munich (Germany)] [and others

2005-05-06

201

Ice limit of Coulomb gauge Yang-Mills theory

In this paper we describe gauge invariant multiquark states generalizing the path integral framework developed by Parrinello, Jona-Lasinio, and Zwanziger to amend the Faddeev-Popov approach. This allows us to produce states such that, in a limit which we call the ice limit, fermions are dressed with glue exclusively from the fundamental modular region associated with Coulomb gauge. The limit can be taken analytically without difficulties, avoiding the Gribov problem. This is illustrated by an unambiguous construction of gauge invariant mesonic states for which we simulate the static quark-antiquark potential.

Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom)

2008-10-01

202

Projectile structure effects in the collisions 6,7Li+64Zn around the Coulomb barrier.

NASA Astrophysics Data System (ADS)

We measured elastic scattering angular distributions and cross sections for heavy residue production for the systems 6,7Li+64Zn at different energies around the Coulomb barrier. The elastic scattering angular distributions have been reproduced by optical model fits using a renormalized double folding potential for the real and imaginary parts. Absence of usual threshold anomaly in the optical potential was found. The excitation functions for heavy residue production were measured using an activation technique. Comparison with different calculations suggest that complete fusion is the dominant reaction mechanism above the barrier whereas, below the Coulomb barrier, incomplete fusion and transfer dominate.

Figuera, P.; Di Pietro, A.; Fisichella, M.; Lattuada, M.; Maiolino, C.; Milin, M.; Musumarra, A.; Ostashko, V.; Pellegriti, M. G.; Randisi, G.; Santonocito, D.; Scuderi, V.; Strano, E.; Torresi, D.; Zadro, M.

2014-03-01

203

Coulomb tunneling for fusion reactions in dense matter: Path integral Monte Carlo versus mean field

We compare Path Integral Monte Carlo calculations by Militzer and Pollock (Phys. Rev. B 71, 134303, 2005) of Coulomb tunneling in nuclear reactions in dense matter to semiclassical calculations assuming WKB Coulomb barrier penetration through the radial mean-field potential. We find a very good agreement of two approaches at temperatures higher than ~1/5 of the ion plasma temperature. We obtain a simple parameterization of the mean field potential and of the respective reaction rates. We analyze Gamow-peak energies of reacting ions in various reaction regimes and discuss theoretical uncertainties of nuclear reaction rates taking carbon burning in dense stellar matter as an example.

A. I. Chugunov; H. E. DeWitt; D. G. Yakovlev

2007-07-24

204

Coulomb dissociation of [sup 11]Li

Kinematically complete measurements for Coulomb dissociation of [sup 11]Li into [sup 9]Li+2[ital n] were made at 28 MeV/nucleon. The [ital n]-[ital n] correlation function suggests a large source size for the two-neutron emission. The electromagnetic excitation spectrum of [sup 11]Li has a peak, as anticipated in low-energy dipole resonance models, but a large post-breakup Coulomb acceleration of the [sup 9]Li fragment is observed, indicating a very short lifetime of the excited state and favoring direct breakup as the dissociation mechanism.

Ieki, K.; Sackett, D.; Galonsky, A.; Bertulani, C.A.; Kruse, J.J.; Lynch, W.G.; Morrissey, D.J.; Orr, N.A.; Schulz, H.; Sherrill, B.M.; Sustich, A.; Winger, J.A. (National Superconducting Cyclotron Laboratory and Department of Physics, Michigan State Unversity, East Lansing, Michigan 48824 (United States)); Deak, F.; Horvath, A.; Kiss, A. (Department of Atomic Physics, Eoetvoes University, Puskin utca 5-7 H-1088 Budapest 8 (Hungary)); Seres, Z. (KFKI Research Institute for Particle and Nuclear Physics of the Hungarian Academy of Sciences, H-1525 Budapest 114 (Hungary)); Kolata, J.J. (Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)); Warner, R.E. (Department of Physics, Oberlin College, Oberlin, Ohio 44074 (United States)); Humphrey, D.L. (Department of Physics, Western Kentucky University, Bowling Green, Kentucky 42101 (United States))

1993-02-08

205

Nonlocal formulation of spin Coulomb drag

NASA Astrophysics Data System (ADS)

The spin Coulomb drag (SCD) effect occurs in materials and devices where charged carriers with different spins exchange momentum via Coulomb scattering. This causes frictional forces between spin-dependent currents that lead to intrinsic dissipation, which may limit spintronics applications. A nonlocal formulation of SCD is developed which is valid for strongly inhomogeneous systems such as nanoscale spintronics devices. This nonlocal formulation of SCD is successfully applied to linewidths of intersubband spin plasmons in semiconductor quantum wells, where experiments have shown that the local approximation fails.

D'Amico, I.; Ullrich, C. A.

2013-10-01

206

Hard pion bremsstrahlung in the Coulomb region

Hard high-energy pion-nucleus bremsstrahlung, $\\pi^- +A\\to\\pi^- +\\gamma +A$, is studied in the Coulomb region, i.e. the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. Special attention is focussed on the possibility of measuring the pion polarizability in such reactions. We study the sensitivity to the structure of the underlying the pion-Compton amplitude through a model with $\\sigma$, $\\rho$, and a_1 exchanges. It is found that the effective energy in the virtual pion-Compton scattering is often so large that the threshold approximation does not apply.

Göran Fäldt; Ulla Tengblad

2007-08-02

207

The LAGEOS satellites orbit and Yukawa-like interactions

Deviations from the gravitational inverse-square-law--as in the case of the hypothesised fifth (gravity-like) force--would lead to new weak interactions between macroscopic objects. These deviations from the usual 1\\/r law for the gravitational potential, and for masses separations ranging through several orders of magnitude, must be studied in order to derive if the supplementary interactions are consistent with Einstein equivalence principle,

D. M. Lucchesi

2004-01-01

208

Bands and Coulomb effects in 50Cr

NASA Astrophysics Data System (ADS)

Experimental evidence for the coexistence of states with different K? value was found in 50Cr. The bandcrossing of the K=0+ ground state band with a K=10+ one is confirmed. Large scale shell model calculations could explain all of the observed experimental features and in particular the known experimental Coulomb energy differences in the mirror pair 50Fe-50Cr.

Brandolini, F.; Sanchez-Solano, J.; Lenzi, S. M.; Medina, N. H.; Poves, A.; Ur, C. A.; Bazzacco, D.; de Angelis, G.; de Poli, M.; Farnea, E.; Gadea, A.; Napoli, D. R.; Rossi-Alvarez, C.

2002-08-01

209

NASA Astrophysics Data System (ADS)

We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (?H = 2) and eight (?1st = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (?minG=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d4 with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step--namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems; however, this scaling can be reduced to linear by introducing more effective techniques for recognizing significant three-center overlap distributions.

Przybytek, Michal; Helgaker, Trygve

2013-08-01

210

NASA Astrophysics Data System (ADS)

Aiming at the investigation of above-threshold ionization in superstrong laser fields with highly charged ions, we develop a Coulomb-corrected strong-field approximation (SFA). The influence of the Coulomb potential of the atomic core on the ionized electron dynamics in the continuum is taken into account via the eikonal approximation, treating the Coulomb potential perturbatively in the phase of the quasiclassical wave function of the continuum electron. In this paper the formalism of the Coulomb-corrected SFA for the nonrelativistic regime is discussed, employing velocity and length gauge. Direct ionization of a hydrogenlike system in a strong linearly polarized laser field is considered. The relation of the results in the different gauges to the Perelomov-Popov-Terent'ev imaginary-time method is discussed.

Klaiber, Michael; Yakaboylu, Enderalp; Hatsagortsyan, Karen Z.

2013-02-01

211

A nonlinear Bloch model for Coulomb interaction in quantum dots

A nonlinear Bloch model for Coulomb interaction in quantum dots Brigitte Bidegaray-Fesquet and Kole a Coulomb Hamiltonian for electronÂ electron interaction in quantum dots in the Heisenberg picture. Then we-Bloch model, quantum dot, Coulomb interaction, Cauchy problem, Liouville model, positiveness properties. 1

212

Quantum partner-dance in the 12C + 12C system yields sub-Coulomb fusion resonances

NASA Astrophysics Data System (ADS)

A preliminary study of the 12C + 12C sub-Coulomb fusion reaction using the time-dependent wave-packet method is presented. The theoretical sub-Coulomb fusion resonances seem to correspond well with observations. The present method might be a more suitable tool for expanding the cross-section predictions towards lower energies than the commonly used potential-model approximation.

Diaz-Torres, Alexis; Wiescher, Michael

2014-03-01

213

Elastic scattering of 9Li on 208Pb at energies around the Coulomb barrier

NASA Astrophysics Data System (ADS)

We have studied the dynamical effects of the halo structure of 11Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated 11Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. 9Li on 208Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

Cubero, M.; Fernández-García, J. P.; Lay, J. A.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Borge, M. J. G.; Buchmann, L.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gómez-Camacho, J.; Martel, I.; Moro, A. M.; Mukha, I.; Nilsson, T.; Sánchez-Benítez, A. M.; Shotter, A.; Tengblad, O.; Walden, P.

2011-10-01

214

Coulomb drag and spin drag in the presence of spin-orbit coupling

NASA Astrophysics Data System (ADS)

Employing diagrammatic perturbation theory, we calculate the (charge) Coulomb drag resistivity ?D and spin Coulomb drag resistivity ??? in the presence of Rashba spin-orbit coupling. Analytical expressions for ?D and ??? are derived, and it is found that spin-orbit interaction produces a small enhancement to ?D and ??? for weakly disordered systems (Boltzmann regime) while ?D is unchanged for dirty systems (diffusive regime). This enhancement in the Boltzmann regime is attributed to the enhancement of the nonlinear susceptibility (i.e., current produced through the rectification of the thermal electric potential fluctuations in the passive layer) while the lack of enhancement in the diffusive regime is due to the suppression by disorder.

Tse, Wang-Kong; Das Sarma, S.

2007-01-01

215

If Coulomb's law were not inverse square: The charge distribution inside a solid conducting sphere

NASA Astrophysics Data System (ADS)

The distribution of charge between concentric conducting shells has been at the heart of the most sensitive tests of the exponent in Coulomb's law since the days of Henry Cavendish. But it appears that no one has ever answered the question of how an excess of charge would distribute itself throughout the interior of a solid conductor if Coulomb's law were other than inverse square. Spherically symmetric solutions to this problem have been found under the assumption that the potential of a point charge varies either as e-kr/r or as 1/rn.

Spencer, Ross L.

1990-04-01

216

Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier

We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

Cubero, M. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); CICANUM, Universidad de Costa Rica, Apdo. 2060, San Jose (Costa Rica); Fernandez-Garcia, J. P.; Alvarez, M. A. G. [Departamento de FAMN, Universidad de Sevilla, Apdo. 1065, E-41080 Sevilla (Spain); Centro Nacional de Aceleradores, Avda. Thomas A. Edison, E-41092, Sevilla (Spain); Lay, J. A.; Moro, A. M. [Departamento de FAMN, Universidad de Sevilla, Apdo. 1065, E-41080 Sevilla (Spain); Acosta, L.; Martel, I.; Sanchez-Benitez, A. M. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Huelva (Spain); Alcorta, M.; Borge, M. J. G.; Tengblad, O. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Buchmann, L.; Shotter, A.; Walden, P. [TRIUMF, V6T2A3 Vancouver B.C. (Canada); Diget, D. G.; Fulton, B. [Department of Physics, University of York, YO10 5DD Heslington, York (United Kingdom); Fynbo, H. O. U. [Department of Physics and Astronomy, University ofAarhus, DK-8000, Aarhus (Denmark); Galaviz, D. [Centro de Fisica Nuclear da Universidade de Lisboa, 1649-003 Lisbon (Portugal); Gomez-Camacho, J. [Centro Nacional de Aceleradores, Avda. Thomas A. Edison, E-41092, Sevilla (Spain); Departamento de FAMN, Universidad de Sevilla, Apdo. 1065, E-41080 Sevilla (Spain); Mukha, I. [Instituto de Fisica Corpuscular, CSIC-Universidadde Valencia (Spain)

2011-10-28

217

Infrared behavior of the Faddeev-Popov operator in Coulomb gauge QCD

We calculate the eigenvalue distribution of the Faddeev-Popov operator in Coulomb gauge QCD using quenched SU(3) lattice simulation. In the confinement phase, the density of the low-lying eigenvalues increases with lattice volume, and the confinement criterion is satisfied. Moreover, even in the deconfinement phase, the behavior of the FP eigenvalue density is qualitatively the same as in the confinement phase. This is consistent with the fact that the color-Coulomb potential is not screened in the deconfined phase.

Y. Nakagawa; A. Nakamura; T. Saito; H. Toki

2007-02-02

218

Path integral treatment for a Coulomb system constrained on D-dimensional sphere and hyperboloid

The propagator relating to the evolution of a particle on the D-sphere and the D-pseudosphere, subjected to the Coulomb potential, was reconsidered in the Faddeev-Senjanovic formalism. The mid-point is privileged. The space-time transformations used make it possible to regularize the singularity and to bring back the problem to its dynamical symmetry SU (1, 1)

Lecheheb, A. [Departement de Physique, Faculte des Sciences, Universite Mentouri, 25000 Constantine (Algeria)]. E-mail: lecheheb@caramail.com; Merad, M. [Departement de Physique, Centre Universitaire de Oum-El-Bouaghi, 04000 Oum-El-Bouaghi (Algeria); Boudjedaa, T. [Laboratoire de Physique Theorique, Faculte des Sciences, Universite de Jijel, BP 98, Ouled Aissa, 18000 Jijel (Algeria)

2007-05-15

219

Bound state of solution of Dirac-Coulomb problem with spatially dependent mass

The bound state solution of Coulomb Potentials in the Dirac equation is calculated for position dependent mass function M(r) within the framework of asymptotic iteration method (AIM). The eigenfunctions are derived in terms of hypergeometric function and function generator equation of AIM.

Eser Olgar; Hayder M. Dhahir; H. Mutaf

2014-09-24

220

Derivation of the nonlinear Schrodinger equation from a many body Coulomb system

We consider the time evolution of N bosonic particles interacting via a mean field Coulomb potential. Suppose the initial state is a product wavefunction. We show that at any finite time the correlation functions factorize in the limit N ? ?. Furthermore, the limiting one particle density matrix satisfies the nonlinear Hartree equation. The key ingredients are the uniqueness of

Laszlo Erdýos

221

Effects of angular dependence of surface diffuseness in deformed nuclei on Coulomb barrier

NASA Astrophysics Data System (ADS)

The angular dependence of surface diffuseness is further discussed. The results of self-consistent calculations are compared with those obtained with the phenomenological mean-field potential. The rather simple parametrizations are suggested. The effects of surface polarization and hexadecapole deformation on the height of the Coulomb barrier are revealed.

Adamian, G. G.; Antonenko, N. V.; Malov, L. A.; Scamps, G.; Lacroix, D.

2014-09-01

222

Using reactivity indicators instead of the electron density to describe Coulomb systems

NASA Astrophysics Data System (ADS)

It is shown that the Fukui function, local softness, softness kernel, and the electrostatic potential are all capable of fully describing every property of a Coulomb system. This gives a new and fundamental insight into these reactivity indicators, and extends recent work on the shape function and the local temperature.

Ayers, Paul W.

2007-04-01

223

Laser-dressed vacuum polarization in a Coulomb field

We investigate quantum electrodynamic effects under the influence of an external, time-dependent electromagnetic field, which mediates dynamic modifications of the radiative corrections. Specifically, we consider the quantum electrodynamic vacuum-polarization tensor under the influence of two external background fields: a strong laser field and a nuclear Coulomb field. We calculate the charge and current densities induced by a nuclear Coulomb field in the presence of a laser field. We find the corresponding induced scalar and vector potentials. The induced potential, in first-order perturbation theory, leads to a correction to atomic energy levels. The external laser field breaks the rotational symmetry of the system. Consequently, the induced charge density is not spherically symmetric, and the energy correction therefore leads to a ''polarized Lamb shift.'' In particular, the laser generates an additional potential with a quadrupole moment. The corresponding laser-dressed vacuum-polarization potential behaves like 1/r{sup 3} at large distances, unlike the Uehling potential, which vanishes exponentially for large r. The energy corrections are of the same order of magnitude for hydrogenic levels, irrespective of the angular momentum quantum number. The induced current leads to a transition dipole moment which oscillates at the second harmonic of the laser frequency and is mediated by second-order harmonic generation in the vacuum-polarization loop. In the far field, at distances r>>1/{omega} from the nucleus ({omega} is the laser frequency), the laser induces mutually perpendicular electric and magnetic fields, which give rise to an energy flux that corresponds to photon fusion leading to the generation of real photons, again at the second harmonic of the laser. Our investigation might be useful for other situations where quantum field theoretic phenomena are subjected to external fields of a rather involved structure.

Milstein, A. I.; Terekhov, I. S.; Jentschura, U. D.; Keitel, C. H. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

2005-11-15

224

Fermi-edge transmission resonance in graphene driven by a single Coulomb impurity.

The interaction between the Fermi sea of conduction electrons and a nonadiabatic attractive impurity potential can lead to a power-law divergence in the tunneling probability of charge through the impurity. The resulting effect, known as the Fermi edge singularity (FES), constitutes one of the most fundamental many-body phenomena in quantum solid state physics. Here we report the first observation of FES for Dirac fermions in graphene driven by isolated Coulomb impurities in the conduction channel. In high-mobility graphene devices on hexagonal boron nitride substrates, the FES manifests in abrupt changes in conductance with a large magnitude ?e(2)/h at resonance, indicating total many-body screening of a local Coulomb impurity with fluctuating charge occupancy. Furthermore, we exploit the extreme sensitivity of graphene to individual Coulomb impurities and demonstrate a new defect-spectroscopy tool to investigate strongly correlated phases in graphene in the quantum Hall regime. PMID:25062215

Karnatak, Paritosh; Goswami, Srijit; Kochat, Vidya; Pal, Atindra Nath; Ghosh, Arindam

2014-07-11

225

Unitarity constraints for Yukawa couplings in the two-Higgs-doublet model type III

NASA Astrophysics Data System (ADS)

Unitarity constraints for Yukawa couplings are considered in the Two-Higgs-Doublet Model type III, by using a general expansion in partial waves for fermionic scattering processes. Constraints over general Flavor Changing Neutral Currents are found from that systematic, wherein such bounds compete with those coming from Lagrangian perturbativity requirement but are weaker than those imposed from phenomenological processes and precision tests. Nevertheless, for bounds based on unitarity, the number of assumptions is the lowest among phenomenological and theoretical limits. Indeed, these new theoretical constraints are independent of scalar masses or mixing angles for this extended Higgs sector, making them less model dependent.

Castillo, Andrés; Diaz, Rodolfo A.; Morales, Jhon

2014-06-01

226

Control of quantum fluctuations for a Yukawa interaction in the Kaluza Klein picture

We study a system of fermions interacting with a scalar field, in 4+1 dimensions where the 5th dimension is compactified, using an exact functional method, where quantum fluctuations are controlled by the amplitude of the bare fermion mass. The integration of our equationsleads to the properties of the dressed Yukawa coupling, that we study at one-loop so as to show the consistency of the approach. Beyond one loop, the non-perturbative aspect of the method gives us the possibility to derive the dynamical fermion mass. The result obtained is cut off independent and this derivation proposes an alternative to the Schwinger-Dyson approach.

Jean Alexandre; Konstantinos Farakos

2006-03-02

227

Yukawas and discrete symmetries in F-theory compactifications without section

In the case of F-theory compactifications on genus-one fibrations without section there are naturally appearing discrete symmetries, which we argue to be associated to geometrically massive U(1) gauge symmetries. These discrete symmetries are shown to induce non-trivial selection rules for the allowed Yukawa couplings in SU(N) gauge theories. The general discussion is exemplified using a concrete Calabi-Yau fourfold realizing an SU(5) GUT model. We observe that M2 instanton effects appear to play a key role in the generation of new superpotential terms and in the dynamics close to phase transition loci.

Iñaki García-Etxebarria; Thomas W. Grimm; Jan Keitel

2014-08-27

228

Yukawas and discrete symmetries in F-theory compactifications without section

In the case of F-theory compactifications on genus-one fibrations without section there are naturally appearing discrete symmetries, which we argue to be associated to geometrically massive U(1) gauge symmetries. These discrete symmetries are shown to induce non-trivial selection rules for the allowed Yukawa couplings in SU(N) gauge theories. The general discussion is exemplified using a concrete Calabi-Yau fourfold realizing an SU(5) GUT model. We observe that M2 instanton effects appear to play a key role in the generation of new superpotential terms and in the dynamics close to phase transition loci.

García-Etxebarria, Iñaki; Keitel, Jan

2014-01-01

229

Numerical simulations of thermal conductivity in dissipative two-dimensional Yukawa systems

NASA Astrophysics Data System (ADS)

Numerical data on the heat transfer constants in two-dimensional Yukawa systems were obtained. Numerical study of the thermal conductivity and diffusivity was carried out for the equilibrium systems with parameters close to conditions of laboratory experiments with dusty plasma. For calculations of heat transfer constants the Green-Kubo formulas were used. The influence of dissipation (friction) on the heat transfer processes in nonideal systems was investigated. The approximation of the coefficient of thermal conductivity is proposed. Comparison of the obtained results to the existing experimental and numerical data is discussed.

Khrustalyov, Yu. V.; Vaulina, O. S.

2012-04-01

230

Geometrical defects in two-dimensional melting of many-particle Yukawa systems

NASA Astrophysics Data System (ADS)

We present a theoretical polygon construction analysis of two-dimensional melting and freezing transitions in many-particle Yukawa systems. Two-dimensional melting transitions can be characterized as proliferation of geometrical defects—nontriangular polygons, obtained by removing unusually long bonds in the triangulation of particle positions. A liquid state is characterized by the temperature-independent number of quadrilaterals and linearly increasing number of pentagons. We analyze specific types of vertices, classified by the type and distribution of polygons surrounding them, and determine temperature dependencies of their concentrations. Solid-liquid phase transitions are followed by the peaks in the abundances of certain types of vertices.

Radzvilavi?ius, Ar?nas

2012-11-01

231

Heat transfer coefficients in two-dimensional Yukawa systems (numerical simulations)

New data on heat transfer in two-dimensional Yukawa systems have been obtained. The results of a numerical study of the thermal conductivity for equilibrium systems with parameters close to the conditions of laboratory experiments in dusty plasma are presented. The Green-Kubo relations are used to calculate the heat transfer coefficients. The influence of dissipation (internal friction) on the heat transfer processes in nonideal systems is studied. New approximations are proposed for the thermal conductivity and diffusivity for nonideal dissipative systems. The results obtained are compared with the existing experimental and numerical data.

Khrustalyov, Yu. V., E-mail: yuri.khrustalyov@gmail.com; Vaulina, O. S. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2013-05-15

232

Numerical simulations of thermal conductivity in dissipative two-dimensional Yukawa systems.

Numerical data on the heat transfer constants in two-dimensional Yukawa systems were obtained. Numerical study of the thermal conductivity and diffusivity was carried out for the equilibrium systems with parameters close to conditions of laboratory experiments with dusty plasma. For calculations of heat transfer constants the Green-Kubo formulas were used. The influence of dissipation (friction) on the heat transfer processes in nonideal systems was investigated. The approximation of the coefficient of thermal conductivity is proposed. Comparison of the obtained results to the existing experimental and numerical data is discussed. PMID:22680584

Khrustalyov, Yu V; Vaulina, O S

2012-04-01

233

Two independent measurements of the Newtonian gravitational constant G, with stated relative uncertainties below 20 ppm, have been reported in the literature. These measurements were carried out at significantly different separations between source and test masses. The close agreement between the two reported values is used to derive constraints on the existence of a single, composition-independent Yukawa interaction at intermediate ranges. These inferred limits are tighter than those obtained through direct search, for ranges between about 2 cm and 1 m. At a range of 10 cm, the improvement is by a factor of approximately 50.

Trenkel, C. [Astrium Ltd., Gunnels Wood Road, Stevenage SG1 2AS (United Kingdom)

2008-06-15

234

Coulomb effects in the interaction of a charged particle with a two-fragment quantum system

A direct method to derive the expression for the polarization potential between a charged particle and a two-fragment quantum system is developed. This method is based on the asymptotic properties of the two-body Coulomb Green function. The explicit form of the polarization potential constant is obtained for low-energy deuteron-nucleus scattering and for ion-hydrogen scattering. The properties of the polarization potential

V. A. Bilyk; V. L. Shablov; P. S. Krstic; D. R. Schultz

1998-01-01

235

Coulomb impurity scattering in topological insulator thin films

NASA Astrophysics Data System (ADS)

Inter-surface coupling in thin-film topological insulators can reduce the surface state mobility by an order of magnitude in low-temperature transport measurements. The reduction is caused by a reduction in the group velocity and an increased sz component of the surface-state spin which weakens the selection rule against large-angle scattering. An intersurface potential splits the degenerate bands into a Rashba-like bandstructure. This reduces the intersurface coupling, it largely restores the selection rule against large angle scattering, and the ring-shaped valence band further reduces backscattering by requiring, on average, larger momentum transfer for backscattering events. The effects of temperature, Fermi level, and intersurface potential on the Coulomb impurity scattering limited mobility are analyzed and discussed.

Yin, Gen; Wickramaratne, Darshana; Zhao, Yuanyuan; Lake, Roger K.

2014-07-01

236

Trapping of topological-structural defects in Coulomb crystals.

We study experimentally and theoretically structural defects which are formed during the transition from a laser cooled cloud to a Coulomb crystal, consisting of tens of ions in a linear radio frequency trap. We demonstrate the creation of predicted topological defects ("kinks") in purely two-dimensional crystals and also find kinks which show novel dynamical features in a regime of parameters not considered before. The kinks are always observed at the center of the trap, showing a large nonlinear localized excitation, and the probability of their occurrence saturates at ?0.5. Simulations reveal a strong anharmonicity of the kink's internal mode of vibration, due to the kink's extension into three dimensions. As a consequence, the periodic Peierls-Nabarro potential experienced by a discrete kink becomes a globally confining potential, capable of trapping one cooled defect at the center of the crystal. PMID:23581315

Mielenz, M; Brox, J; Kahra, S; Leschhorn, G; Albert, M; Schaetz, T; Landa, H; Reznik, B

2013-03-29

237

Feynman rules for Coulomb gauge QCD

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: Black-Right-Pointing-Pointer In Coulomb gauge QCD, we re-express Christ-Lee terms in the Hamiltonian as pseudo-Feynman integrals. Black-Right-Pointing-Pointer This gives a subgraph structure, and allows the ordinary renormalization process. Black-Right-Pointing-Pointer It also leads to cancellation of energy-divergences.

Andrasi, A. [Rudjer Boskovic Institute, Zagreb (Croatia)] [Rudjer Boskovic Institute, Zagreb (Croatia); Taylor, J.C., E-mail: jct@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge (United Kingdom)

2012-10-15

238

Bionic Coulomb phase on the pyrochlore lattice

NASA Astrophysics Data System (ADS)

A class of three-dimensional classical lattice systems with macroscopic ground state degeneracies, most famously the spin ice system, are known to exhibit “Coulomb” phases wherein long wavelength correlations within the ground state manifold are described by an emergent Maxwell electrodynamics. We discuss a more elaborate example of this phenomenon—the four-state Potts model on the pyrochlore lattice—where the long wavelength description now involves three independent gauge fields, as we confirm via simulation. The excitations above the ground state manifold are bions, defects that are simultaneously charged under two of the three gauge fields, and they exhibit an entropic interaction dictated by these charges. We also show that the distribution of flux loops exhibits a scaling with loop length and system size previously identified as characteristic of Coulomb phases.

Khemani, V.; Moessner, R.; Parameswaran, S. A.; Sondhi, S. L.

2012-08-01

239

Coulomb and nuclear breakup of 8B

NASA Astrophysics Data System (ADS)

The cross sections for the (8B,7Be-p) breakup reaction on 58Ni and 208Pb targets at the beam energies of 25.8 MeV and 415 MeV have been calculated within a one-step prior-form distorted-wave Born approximation. The relative contributions of Coulomb and nuclear breakup of dipole and quadrupole multipolarities as well as their interference have been determined. The nuclear breakup contributions are found to be substantial in the angular distributions of the 7Be fragment for angles in the range of 30°-80° at 25.8 MeV beam energy. The Coulomb-nuclear interference terms make the dipole cross section larger than that of quadrupole even at this low beam energy. However, at the incident energy of 415 MeV, these effects are almost negligible in the angular distributions of the (7Be-p) coincidence cross sections at angles below 4°.

Shyam, R.; Thompson, I. J.

1999-05-01

240

Coulomb edge effects in graphene nanoribbons

NASA Astrophysics Data System (ADS)

Coulomb effects in graphene nanoribbons with arbitrary edges are investigated with the use of a mean-field Hubbard model. It was recently shown that chiral ribbons with minimal edges, characterized by the translation vector (n,m), have a similar structure of bands localized around the Fermi energy as pure zigzag ribbons (n-m,0). Here we show that these flat bands in both ribbon cases differ in detail due to the perturbation induced by armchair edge nodes. For chiral ribbons the edge bands split at the zone boundary, where the corresponding bands of (n-m,0) zigzag ribbons are degenerate. Coulomb interactions enhance strongly this splitting and at the same time they bring spin into play. We modify each edge keeping global sublattice balance to find that spin degeneracy can be partially lifted. The breaking of spin-degeneracy depends on the asymmetry between the edges and in some cases leads to spin-polarized currents.

Jaskolski, W.; Ayuela, A.

2014-10-01

241

Pore fluid pressure, apparent friction, and Coulomb failure

Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ? ?? ? 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter ?? is intended to incorporate the effects of both friction and pore pressure, but is a material constant only if changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the potential failure plane. Although specific models of fault zones permit such a relation, neither is it known that fault zones within the Earth behave this way, nor is this behavior expected in all cases. In contrast, for an isotropic homogeneous poroelastic model the pore pressure changes are proportional to changes in mean stress, ?? is not a material constant, and ?? ? ?? ? +?. Analysis of the change in Coulomb failure stress for tectonically loaded reverse and strike-slip faults shows considerable differences between these two pore pressure models, suggesting that such models might be distinguished from one another using observations of triggered seismicity (e.g., aftershocks). We conclude that using the constant apparent friction model exclusively in studies of Coulomb failure stress is unwise and could lead to significant errors in estimated stress change and seismic hazard.

Beeler, N.M.; Simpson, R.W.; Hickman, S.H.; Lockner, D.A.

2000-01-01

242

Coulomb Repulsion in Miniature Ion Mobility Spectrometry

We have undertaken a study of ion mobility resolution in a miniature ion mobility spectrometer with a drift channel 1.7 mm in diameter and 35 mm in length. The device attained a maximum resolution of 14 in separating ions of NO, Oâ, and methyl iodine. The ions were generated by pulses from a frequency-quadrupled Nd:YAG laser. Broadening due to Coulomb

J. Xu; W. B. Whitten; J. M. Ramsey

1999-01-01

243

A new general form of the multi-Yukawa, multicomponent closure of the Ornstein–Zernike equation for factored interactions is derived. The general solution is given in terms of an M × M scaling matrix obtained by solving M (equal to the number of Yukawa terms in the closure) equations together with M(M ? 1) symmetry conditions where ??( n) is of higher

L Blum; J A Hernando

2002-01-01

244

Yukawa-field approximation of electrostatic free energy and dielectric boundary force This article.1088/0951-7715/24/11/011 Yukawa-field approximation of electrostatic free energy and dielectric boundary force Hsiao-Bing Cheng1. The electrostatic free energy determines the dielectric boundary force that in turn influences crucially

Li, Bo

245

Effective Yukawa couplings and flavor-changing Higgs boson decays at linear colliders

We analyze the advantages of a linear-collider program for testing a recent theoretical proposal where the Higgs boson Yukawa couplings are radiatively generated, keeping unchanged the standard-model mechanism for electroweak-gauge-symmetry breaking. Fermion masses arise at a large energy scale through an unknown mechanism, and the standard model at the electroweak scale is regarded as an effective field theory. In this scenario, Higgs boson decays into photons and electroweak gauge-boson pairs are considerably enhanced for a light Higgs boson, which makes a signal observation at the LHC straightforward. On the other hand, the clean environment of a linear collider is required to directly probe the radiative fermionic sector of the Higgs boson couplings. Also, we show that the flavor-changing Higgs boson decays are dramatically enhanced with respect to the standard model. In particular, we find a measurable branching ratio in the range (10{sup -4}-10{sup -3}) for the decay H{yields}bs for a Higgs boson lighter than 140 GeV, depending on the high-energy scale where Yukawa couplings vanish. We present a detailed analysis of the Higgs boson production cross sections at linear colliders for interesting decay signatures, as well as branching-ratio correlations for different flavor-conserving/nonconserving fermionic decays.

Gabrielli, E. [CERN, PH-TH, CH-1211 Geneva 23 (Switzerland); Mele, B. [INFN, Sezione di Roma, c/o Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale A. Moro 2, I-00185 Rome (Italy)

2011-04-01

246

Upper and lower Higgs boson mass bounds from a chirally invariant lattice Higgs-Yukawa model

Motivated by the advent of the Large Hadron Collider the aim of the present work is the non-perturbative determination of the cutoff-dependent upper and lower mass bounds of the Standard Model Higgs boson based on first principle calculations, in particular not relying on additional information such as the triviality property of the Higgs-Yukawa sector or indirect arguments like vacuum stability considerations. For that purpose the lattice approach is employed to allow for a non-perturbative investigation of a chirally invariant lattice Higgs-Yukawa model, serving here as a reasonable simplification of the full Standard Model, containing only those fields and interactions which are most essential for the intended Higgs boson mass determination. These are the complex Higgs doublet as well as the top and bottom quark fields and their mutual interactions. To maintain the chiral character of the Standard Model Higgs-fermion coupling also on the lattice, the latter model is constructed on the basis of the Neuberger overlap operator, obeying then an exact global lattice chiral symmetry.

P. Gerhold

2010-02-12

247

bbH production at the CERN LHC: Yukawa corrections and the leading Landau singularity

At tree-level Higgs production in association with a b-quark pair proceeds through the small Yukawa bottom coupling in the standard model. Even in the limit where this coupling vanishes, electroweak one-loop effects, through the top-Higgs Yukawa coupling, in particular, can still trigger this reaction. This contribution is small for Higgs masses around 120 GeV but it quickly picks up for higher Higgs masses especially because the one-loop amplitude develops a leading Landau singularity and new thresholds open up. These effects can be viewed as the production of a pair of top quarks which rescatter to give rise to Higgs production through WW fusion. We study the leading Landau singularity in detail. Since this singularity is not integrable when the one-loop amplitude is squared, we regulate the cross section by taking into account the width of the internal top and W particles. This requires that we extend the usual box one-loop function to the case of complex masses. We show how this can be implemented analytically in our case. We study in some detail the cross section at the CERN LHC as a function of the Higgs mass and show how some distributions can be drastically affected compared to the tree-level result.

Boudjema, F.; Duc Ninh Le [LAPTH, Universite de Savoie, CNRS, BP 110, F-74941 Annecy-le-Vieux Cedex (France)

2008-11-01

248

Measuring the top Yukawa coupling at the ILC at sqrt(s) = 500 GeV

We report on the feasibility of the direct measurement of the top Yukawa coupling g_t at the International Linear Collider (ILC) during its first phase of operation with a center-of-mass energy of 500 GeV. The signal and background models incorporate the non-relativistic QCD corrections which enhance the production cross section near the t-tbar threshold. The e+e- -> t tbar H signal is reconstructed in the 6-jet + lepton and the 8-jet modes. The results from the two channels are combined. The background processes considered are e+e- -> t bbar W- / tbar b W+ (which includes e+e- -> t tbar), e+e- -> t tbar Z, and e+e- -> t tbar g* -> t tbar b bar. We use a realistic fast Monte-Carlo detector simulation. Signal events are selected using event shape variables, through jet clustering, and by identifying heavy flavor jets. Assuming a Higgs mass of 120 GeV, polarized electron and positron beams with (Pe-,Pe+) = (-0.8,+0.3), and an integrated luminosity of 1 ab-1, we estimate that the e+e- -> t tbar H events can be seen with a statistical significance of 5.2 sigma, corresponding to the relative top Yukawa coupling measurement accuracy of |Delta g_t / g_t| = 10%.

Ryo Yonamine; Katsumasa Ikematsu; Tomohiko Tanabe; Keisuke Fujii; Yuichiro Kiyo; Yukinari Sumino; Hiroshi Yokoya

2011-04-27

249

Properties of gravitationally equilibrated Yukawa systems-A molecular dynamics study

NASA Astrophysics Data System (ADS)

Using 2D Molecular Dynamics simulation, the equilibrium and dynamical properties of a gravitationally equilibrated Yukawa liquid are investigated. We observe that due to asymmetry introduced in one direction by gravity, several interesting features arise. For example, for a given value of coupling parameter ?, screening parameter ?, and according to a chosen value of gravitational force g (say in y-direction), the system is seen to exhibit super-, sub- or normal diffusion. Interestingly, x-averaged density profiles, unlike a barotropic fluid, acquires sharp, free surface with scale free linear y-dependence. As can be expected for a system with macroscopic gradients, self-diffusion calculated from Green-Kubo's formalism does not agree with that obtained from Einstein-Smoluchowski diffusion. A 2D angular-radial pair correlation function g(r, ?) clearly indicates asymmetric features induced by gravity. We observe that due to compression in y-direction, though in liquid state for all values of gravity considered, the transverse mode is found to predominant as compared to the longitudinal mode, leading to a novel Anisotropic Solid-like Yukawa liquid.

Charan, Harish; Ganesh, Rajaraman; Joy, Ashwin

2014-04-01

250

Non-commutative relativistic equation with a Coulomb potential

We improve the previous study of the Klein-Gordon equation in a non-commutative space-time as applied to the Hydrogen atom to extract the energy levels, by considering the secondorder corrections in the non-commutativity parameter. Phenomenologically we show that noncommutativity plays the role of spin.

Zaim, Slimane; Khodja, Lamine; Delenda, Yazid [Departement de Physique, Faculte des Sciences, Universite Hadj Lakhdar - Batna (Algeria); Departement de Physique, Faculte des Sciences Exactes, Universite de Bejaia (Algeria); Departement de Physique, Faculte des Sciences, Universite Hadj Lakhdar - Batna (Algeria)

2012-06-27

251

BRIEF COMMUNICATION: A note on the Coulomb collision operator in curvilinear coordinates

NASA Astrophysics Data System (ADS)

The dynamic friction force, diffusion tensor, flux density in velocity space and Coulomb collision term are expressed in curvilinear coordinates via Trubnikov potential functions corresponding to each species of a background plasma. For comparison, explicit formulae are given for the dynamic friction force, diffusion tensor and collisional flux density in velocity space in curvilinear coordinates via Rosenbluth potential functions summed over all species of the background plasma.

Goncharov, P. R.

2010-10-01

252

Perturbation theory in the Hamiltonian approach to Yang-Mills theory in Coulomb gauge

We study the Hamiltonian approach to Yang-Mills theory in Coulomb gauge in Rayleigh-Schroedinger perturbation theory. The static gluon and ghost propagator as well as the potential between static color sources are calculated to one-loop order. Furthermore, the one-loop {beta} function is calculated from both the ghost-gluon vertex and the static potential and found to agree with the result of covariant perturbation theory.

Campagnari, Davide R.; Reinhardt, Hugo; Weber, Axel [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio C-3, Ciudad Universitaria, A. Postal 2-82, 58040 Morelia, Michoacan (Mexico)

2009-07-15

253

Based on a recent result showing that the net Coulomb potential in condensed ionic systems is rather short ranged, an exact and physically transparent method permitting the evaluation of the Coulomb potential by direct summation over the r{sup {minus}1} Coulomb pair potential is presented. The key observation is that the problems encountered in determining the Coulomb energy by pairwise, spherically truncated r{sup {minus}1} summation are a direct consequence of the fact that the system summed over is practically never neutral. A simple method is developed that achieves charge neutralization wherever the r{sup {minus}1} pair potential is truncated. This enables the extraction of the Coulomb energy, forces, and stresses from a spherically truncated, usually charged environment in a manner that is independent of the grouping of the pair terms. The close connection of our approach with the Ewald method is demonstrated and exploited, providing an efficient method for the simulation of even highly disordered ionic systems by direct, pairwise r{sup {minus}1} summation with spherical truncation at rather short range, i.e., a method which fully exploits the short-ranged nature of the interactions in ionic systems. The method is validated by simulations of crystals, liquids, and interfacial systems, such as free surfaces and grain boundaries. {copyright} {ital 1999 American Institute of Physics.}

Wolf, D.; Keblinski, P.; Phillpot, S.R.; Eggebrecht, J. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

1999-05-01

254

"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

NASA Technical Reports Server (NTRS)

The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this very brief (30-60 sec) damping period, motion of the grains was observed to be retarded by the electrostatic interactions. The fact that the grains almost instantly formed aggregates was evidence that their ballistic motions had been constrained and redirected by the dipole-dipole interactions that led to filamentary aggregate development. Undoubtedly, the "Coulombic viscosity" of the cloud assisted in damping grain motion so rapidly. The electrostatically-induced grain-cloud viscosity or drag exerted on grain motion, is a complex function of three major parameters: charge magnitude, charge sign, and mean intergranular distance. The above experiments illustrate one particular type of granular behavior. The discussion here will therefore be restricted to drag relationships: (a) between grains that are naturally charged triboelectrically and thus exhibit dipole-dipole attractions between one another even if there are slight net charges present (which can be overwhelmed by dipole coupling at short distances), and (b) between grains that are densely spaced where the intergranular distance varies between zero and some value (usually tens or hundreds of grain diameters) that permits each grain to detect the dipole moment of another grain -- the distance is not so great that other grains appears as neutral electrical "singularities. I. Aeolian transport: During motion of grains in a saltation cloud (on Earth, Mars, or Venus), triboelectric charging must occur as a result of multiple grain contacts, and by friction with the entraining air. A situation might develop that is similar to the one described above in the attrition device: grain motion becoming significantly retarded (reduced flux) as grains find it increasingly difficult to either separate from the surface, or to pass one another without Coulombic retarding forces. A "Coulombic drag" will exist at flux initiation and increase with time to work in direct opposition to the aerodynamic drag that drives the grain motion. It is predicted that this will lead to an increase

Marshall, J. R.

1999-01-01

255

On the temperature dependence of ballistic Coulomb drag in nanowires

NASA Astrophysics Data System (ADS)

We have investigated within Fermi liquid theory the dependence of Coulomb drag current in a passive quantum wire on the applied voltage V across an active wire and on the temperature T for any values of eV/kBT. We assume that the bottoms of the 1D minibands in both wires almost coincide with the Fermi level. We conclude that: (1) within a certain temperature interval the drag current can be a descending function of the temperature T; (2) the experimentally observed temperature dependence T-0.77 of the drag current can be interpreted within the framework of Fermi liquid theory; (3) at relatively high applied voltages the drag current saturates as a function of the applied voltage; and (4) the screening of the electron potential by metallic gate electrodes can be of importance.

Muradov, M. I.; Gurevich, V. L.

2012-04-01

256

Coulomb gauge confinement in the heavy quark limit

The relationship between the nonperturbative Green's functions of Yang-Mills theory and the confinement potential is investigated. By rewriting the generating functional of quantum chromodynamics in terms of a heavy quark mass expansion in Coulomb gauge, restricting to leading order in this expansion and considering only the two-point functions of the Yang-Mills sector, the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is shown to be exact in this case and an analytic, nonperturbative solution is presented. It is found that there is a direct connection between the string tension and the temporal gluon propagator. Further, it is shown that for the 4-point quark correlation functions, only confined bound states of color-singlet quark-antiquark (meson) and quark-quark (baryon) pairs exist.

Popovici, C.; Watson, P.; Reinhardt, H. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2010-05-15

257

Strong nuclear couplings as a source of Coulomb rainbow suppression

NASA Astrophysics Data System (ADS)

A recent measurement of the Be11+Zn64 quasielastic scattering angular distribution exhibits a non-Fresnel-type pattern, in contrast to He6+Zn64 elastic scattering but similar to that for the elastic scattering of He6 from heavy targets. We show by means of continuum discretized coupled-channels (CDCC) calculations that this unusual behavior of Be11 is caused by the much greater importance of nuclear coupling to the continuum in Be11 compared to He6, where Coulomb dipole coupling is mainly responsible for the non-Fresnel-like shape, when present. We also show that the dynamic polarization potentials derived from the CDCC calculations seem to follow a universal form as a function of radius.

Keeley, N.; Alamanos, N.; Kemper, K. W.; Rusek, K.

2010-09-01

258

We study a chirally invariant Higgs-Yukawa model regulated on a space-time lattice. We calculate Higgs boson resonance parameters and mass bounds for various values of the mass of the degenerate fermion doublet. Also, first results on the phase transition temperature are presented. In general, this model may be relevant for BSM scenarios with a heavy fourth generation of quarks.

John Bulava; Philip Gerhold; Karl Jansen; Jim Kallarackal; Attila Nagy

2011-11-11

259

Yukawa Monte Carlo and Molecular Dynamics simulations are powerful techniques extensively used to compute plasma properties such as EOS or transport coefficients, but are limited to applications where the linear electronic screening assumption is valid (1). Recently we have shown that a modified scheme using density functional theory with a Thomas-Fermi kinetic energy functional for the electrons (OFMD) may be

Dominique Gilles; Flavien Lambert; Jean Clerouin

2008-01-01

260

Mathematical Structure of Relativistic Coulomb Integrals

We show that the diagonal matrix elements $,$ where $O$ $={1,\\beta,i\\mathbf{\\alpha n}\\beta}$ are the standard Dirac matrix operators and the angular brackets denote the quantum-mechanical average for the relativistic Coulomb problem, may be considered as difference analogs of the radial wave functions. Such structure provides an independent way of obtaining closed forms of these matrix elements by elementary methods of the theory of difference equations without explicit evaluation of the integrals. Three-term recurrence relations for each of these expectation values are derived as a by-product. Transformation formulas for the corresponding generalized hypergeometric series are discussed.

Sergei K. Suslov

2009-10-31

261

Coulomb drag between one-dimensional conductors

We have analyzed Coulomb drag between currents of interacting electrons in two parallel one-dimensional conductors of finite length L attached to external reservoirs. For strong coupling, the relative fluctuations of electron density in the conductors acquire energy gap M. At energies larger than gamma = constxv(-)exp(-LM/v(-))/L+gamma(+), where gamma(+) is the impurity scattering rate, and, for L>v(-)/M, where v(-) is the fluctuation velocity, the gap leads to an "ideal" drag with almost equal currents in the conductors. At low energies the drag is suppressed by coherent instanton tunneling, and the zero-temperature transconductance vanishes, indicating the Fermi-liquid behavior. PMID:11102153

Ponomarenko; Averin

2000-12-01

262

Coulomb excitation of cadmium isotopes with protons

Low-lying positive parity levels of the isotopes in natural cadmium were Coulomb excited with 2.7-4.2 MeV protons. Eight levels of 111Cd up to 1130.4 keV and four levels of 113Cd up to 680.5 keV excitation energy, and the first 2+ states in even-even isotopes (110,112,114,116Cd) were excited. A 50 cm3 Ge(Li) detector was used to measure the deexcitation gamma-ray yields.

K. P. Singh; D. C. Tayal; Gulzar Singh; H. S. Hans

1985-01-01

263

Coulomb excitation of cadmium isotopes with protons

Low-lying positive parity levels of the isotopes in natural cadmium were Coulomb excited with 2.7--4.2 MeV protons. Eight levels of Â¹Â¹Â¹Cd up to 1130.4 keV and four levels of Â¹Â¹Â³Cd up to 680.5 keV excitation energy, and the first 2\\/sup +\\/ states in even-even isotopes (\\/sup 110,112,114,116\\/Cd) were excited. A 50 cmÂ³ Ge(Li) detector was used to measure the deexcitation

K. P. Singh; D. C. Tayal; Gulzar Singh; H. S. Hans

1985-01-01

264

Two-body Coulomb problems with sources

The two-body Coulomb Schroedinger equation with different types of nonhomogeneities are studied. The particular solution of these nonhomogeneous equations is expressed in closed form in terms of a two-variable hypergeometric function. A particular representation of the latter allows one to study efficiently the solution in the asymptotic limit of large values of the coordinate and hence the associated physics. Simple sources are first considered, and a complete analysis of scattering and bound states is performed. The solutions corresponding to more general (arbitrary) sources are then provided and written in terms of more general hypergeometric functions.

Gasaneo, G. [Departamento de Fisica, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8000 Bahia Blanca, Buenos Aires (Argentina); Ancarani, L. U. [Laboratoire de Physique Moleculaire et des Collisions, Universite Paul Verlaine-Metz, F-57078 Metz (France)

2010-10-15

265

Multiple Coulomb Scattering in Thin Silicon

We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50-140 um) 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.

Niklaus Berger; Armen Buniatyan; Patrick Eckert; Fabian Förster; Roman Gredig; Oxana Kovalenko; Moritz Kiehn; Raphael Philipp; André Schöning; Dirk Wiedner

2014-05-12

266

Multiple Coulomb Scattering in Thin Silicon

We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50-140 um) 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.

Berger, Niklaus; Eckert, Patrick; Förster, Fabian; Gredig, Roman; Kovalenko, Oxana; Kiehn, Moritz; Philipp, Raphael; Schöning, André; Wiedner, Dirk

2014-01-01

267

Multiple Coulomb scattering in thin silicon

NASA Astrophysics Data System (ADS)

We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50-140 ?m) 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.

Berger, N.; Buniatyan, A.; Eckert, P.; Förster, F.; Gredig, R.; Kovalenko, O.; Kiehn, M.; Philipp, R.; Schöning, A.; Wiedner, D.

2014-07-01

268

Yukawa coupling beta-functions in the Standard Model at three loops

NASA Astrophysics Data System (ADS)

We present the results for three-loop beta-functions for Yukawa couplings of heavy Standard Model fermions calculated within the unbroken phase of the model. The calculation is carried out with the help of the MINCER program in a general linear gauge, and the final result is independent of the gauge-fixing parameters. In order to calculate three-point functions, we made use of infrared rearrangement (IRR) trick. Due to the chiral structure of the SM a careful treatment of loops with fermions is required to perform the calculation. It turns out that gauge anomaly cancellation in the SM allows us to obtain the result by means of the semi-naive treatment of ?5.

Bednyakov, A. V.; Pikelner, A. F.; Velizhanin, V. N.

2013-05-01

269

Theoretical perspective on nearly frozen coulomb liquids

NASA Astrophysics Data System (ADS)

Various studies on systems with charge ordered states, such as Wigner crystal, show their extreme fragility resulting from strong frustrations caused by long-range Colulomb-like interactions. Here, a so-called nearly-frozen Coulomb liquid regime is identified featuring a soft Coulomb pseudo-gap with unconventional insulating-like transport. Despite intensive studies, such pseudo-gap regime is still poorly understood. By employing extended dynamical mean field theory (EDMFT) [1] to study a semi-classical lattice gas model of spinless electrons, we successfully demonstrate the existence of such an intermediate liquid regime, and show that the pseudo-gap is, in fact, a general feature for models with long-range interactions. Our analytical results are well supported by exact Monte Carlo calculations. Moreover, we show that standard theories, like self-consistent Gaussian approximation ("spherical model") and RPA, are ill-suited to describe this interesting regime. The spherical model approach provides the same as EDMFT freezing temperature Tc, but fails to capture the pseudo-gap feature. RPA, however, not only overestimates Tc, but also completely misses the pseudo-gap regime. [0pt] [1] S. Pankov and V. Dobrosavljevic, Phys. Rev. Lett. 94, 046402 (2005).

Terletska, Hanna; Pramudya, Yohanes; Pankov, Sergey; Manousakis, Efstratios; Dobrosavljevic, Vladimir

2011-03-01

270

Landscaping with fluxes and the E8 Yukawa Point in F-theory

Integrality in the Hodge theory of Calabi-Yau fourfolds is essential to find the vacuum structure and the anomaly cancellation mechanism of four dimensional F-theory compactifications. We use the Griffiths-Frobenius geometry and homological mirror symmetry to fix the integral monodromy basis in the primitive horizontal subspace of Calabi-Yau fourfolds. The Gamma class and supersymmetric localization calculations in the 2d gauged linear sigma model on the hemisphere are used to check and extend this method. The result allows us to study the superpotential and the Weil-Petersson metric and an associated tt* structure over the full complex moduli space of compact fourfolds for the first time. We show that integral fluxes can drive the theory to N=1 supersymmetric vacua at orbifold points and argue that fluxes can be chosen that fix the complex moduli of F-theory compactifications at gauge enhancements including such with U(1) factors. Given the mechanism it is natural to start with the most generic complex structure families of elliptic Calabi-Yau 4-fold fibrations over a given base. We classify these families in toric ambient spaces and among them the ones with heterotic duals. The method also applies to the creating of matter and Yukawa structures in F-theory. We construct two SU(5) models in F-theory with a Yukawa point that have a point on the base with an $E_8$-type singularity on the fiber and explore their embeddings in the global models. The explicit resolution of the singularity introduce a higher dimensional fiber and leads to novel features.

Nana Cabo Bizet; Albrecht Klemm; Daniel Vieira Lopes

2014-04-30

271

Positive and negative Coulomb drag in vertically integrated one-dimensional quantum wires

NASA Astrophysics Data System (ADS)

Electron interactions in and between wires become increasingly complex and important as circuits are scaled to nanometre sizes, or use reduced-dimensional conductors such as carbon nanotubes, nanowires and gated high-mobility two-dimensional electron systems. This is because the screening of the long-range Coulomb potential of individual carriers is weakened in these systems, which can lead to phenomena such as Coulomb drag, where a current in one wire induces a voltage in a second wire through Coulomb interactions alone. Previous experiments have demonstrated Coulomb electron drag in wires separated by a soft electrostatic barrier of width >~80 nm (ref. 12), which was interpreted as resulting entirely from momentum transfer. Here, we measure both positive and negative drag between adjacent vertical quantum wires that are separated by ~15 nm and have independent contacts, which allows their electron densities to be tuned independently. We map out the drag signal versus the number of electron sub-bands occupied in each wire, and interpret the results both in terms of momentum-transfer and charge-fluctuation induced transport models. For wires of significantly different sub-band occupancies, the positive drag effect can be as large as 25%.

Laroche, D.; Gervais, G.; Lilly, M. P.; Reno, J. L.

2011-12-01

272

Evaluation of negative energy Coulomb (Whittaker) functions

NASA Astrophysics Data System (ADS)

This paper describes a code for evaluating exponentially decaying negative energy Coulomb functions and their first derivatives with respect to the radial variable. The functions, which correspond to Whittaker functions of the second kind, are obtained to high accuracy for a wide range of parameters using recurrence techniques. Program summaryTitle of program: whittaker_w Catalog identifier: ADSZ Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSZ Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: Cray T3E, Sun Ultra-5_10 sparc, Origin2000, Compaq EV67, IBM SP3, Toshiba 460CDT Operating systems under which the program has been tested: Windows NT4, Redhat Linux, SunOS 5.8 Programming language used: Fortran 95 Memory required to run with typical data: 500 KB Number of bytes in distributed program, including test data, etc.: 39728 Number of lines in distributed program, including test data, etc.: 2900 Distribution format: tar gzip file Nature of physical problem: The closed-channel components of the asymptotic radial wave function corresponding to electron or positron scattering by atomic or molecular ions may be expressed in terms of negative energy Coulomb functions. The scattering observables are obtained from S or T matrices which in turn are obtained by matching the radial and asymptotic wavefunctions at a finite radial point. Recent large scale scattering calculations have required accurate values of the Coulomb functions at smaller ? values and larger negative ? values than previous work. The present program is designed to extend the range of parameters for which the function may be calculated. Method of solution: Recurrence relations, power series expansion, numerical quadrature. Restrictions on the complexity of the problem: The program has been tested for the parameter ranges: 0< ??1000, | ?|?120 and 0? l?100. These ranges may, with appropriate scaling to avoid underflow and overflow, be extended. References: A. Sunderland, C.J. Noble, P.G. Burke, V.M. Burke, Comp. Phys. Commun. 145 (2002) 311.

Noble, C. J.

2004-05-01

273

Quantum Dynamics of Biological Plasma in the External Coulomb Field

NASA Astrophysics Data System (ADS)

A quantum solution to the truncated Fisher-Kolmogorov-Petrovskii-Piskunov equation with Coulomb convection and linear diffusion is derived. The quantum radiation of biological systems, individual microorganisms (cells, bacteria), and dust plasma particles in the Coulomb field is studied using the foregoing solution.

Lasukov, V. V.; Lasukova, T. V.; Lasukova, O. V.

2013-10-01

274

The Effect of coulomb friction and stiction on force control

We have studied the effect of Coulomb friction and stiction on force control with integral feedback. The force is applied through a compliant transmission by a velocity-controlled motor. Our results show that stiction can cause the applied force to enter a limit cycle. Coulomb friction can extend the system stability bounds but may lead to an input-dependent stability. Under certain

William T. Townsend

1987-01-01

275

Known-to-Unknown Approach to Teach about Coulomb's Law

ERIC Educational Resources Information Center

Analogies from life experiences help students understand various relationships presented in an introductory chemistry course. Coulomb's law is a complex relationship encountered in introductory general chemistry. A proper understanding of the relationships between the quantities involved in Coulomb's law is necessary in order for students to…

Thamburaj, P. K.

2007-01-01

276

An eikonal expansion is developed in order to provide systematic corrections to the eikonal approximation through order 1/k^2, where k is the wave number. The expansion is applied to wave functions for the Klein-Gordon equation and for the Dirac equation with a Coulomb potential. Convergence is rapid at energies above about 250 MeV. Analytical results for the eikonal wave functions are obtained for a simple analytical form of the Coulomb potential of a nucleus. They are used to investigate distorted-wave matrix elements for quasi-elastic electron scattering from a nucleus. Focusing factors are shown to arise from the corrections to the eikonal approximation. A precise form of the effective-momentum approximation is developed by use of a momentum shift that depends on the electron's energy loss.

J. A. Tjon; S. J. Wallace

2006-10-27

277

Screening of Coulomb Impurities in Graphene

We calculate exactly the vacuum polarization charge density in the field of a subcritical Coulomb impurity, $Z|e|/r$, in graphene. Our analysis is based on the exact electron Green's function, obtained by using the operator method, and leads to results that are exact in the parameter $Z\\alpha$, where $\\alpha$ is the "fine structure constant" of graphene. Taking into account also electron-electron interactions in the Hartree approximation, we solve the problem self-consistently in the subcritical regime, where the impurity has an effective charge $Z_{eff}$, determined by the localized induced charge. We find that an impurity with bare charge Z=1 remains subcritical, $Z_{eff} \\alpha < 1/2$, for any $\\alpha$, while impurities with $Z=2,3$ and higher can become supercritical at certain values of $\\alpha$.

Terekhov, Ivan S; Kotov, Valeri N; Sushkov, Oleg P

2008-01-01

278

Screening of coulomb impurities in graphene.

We calculate exactly the vacuum polarization charge density in the field of a subcritical Coulomb impurity, Z|e|/r, in graphene. Our analysis is based on the exact electron Green's function, obtained by using the operator method, and leads to results that are exact in the parameter Zalpha, where alpha is the "fine-structure constant" of graphene. Taking into account also electron-electron interactions in the Hartree approximation, we solve the problem self-consistently in the subcritical regime, where the impurity has an effective charge Z(eff), determined by the localized induced charge. We find that an impurity with bare charge Z=1 remains subcritical, Z(eff)alpha<1/2, for any alpha, while impurities with Z=2, 3 and higher can become supercritical at certain values of alpha. PMID:18352585

Terekhov, Ivan S; Milstein, Alexander I; Kotov, Valeri N; Sushkov, Oleg P

2008-02-22

279

The ghost propagator in Coulomb gauge

We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until 'forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

Watson, P.; Reinhardt, H. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2011-05-23

280

Loop statistics in the Coulomb phase

NASA Astrophysics Data System (ADS)

The Coulomb phase is a classical gauge field theory arising in frustrated systems with ``divergence free'' constraints, such as spin ice [1]. In this talk, we show how this phase can be understood as a loop model, and characterized by their loop length distribution and fractal dimensions [2]. Comparing similar models in 2- and 3-dimensions allows us to extract insights from connections to Stochastic-Loewner Evolution (SLE) processes, percolation and polymer physics. We mention implications of these results for related models and experiments (Heisenberg magnets, itinerant electrons [3]). [4pt] [1] Henley, Annual Review of Condensed Matter Physics 1, 179 (2010).[0pt] [2] Jaubert, Haque, Moessner, Phys. Rev. Lett. 107, 177202 (2011)[0pt] [3] Jaubert, Pitaecki, Haque & Moessner, in preparation (2012).

Jaubert, Ludovic; Haque, Masud; Moessner, Roderich

2012-02-01

281

Coulomb energy differences in mirror nuclei revisited

We calculate the Coulomb displacement energies (CDEs) of mirror nuclei using the recent parameter set (NL3) in the relativistic mean-field (RMF) model which includes self-coupling of the scalar meson. The results obtained are compared with the available ones calculated in the nonrelativistic Skyrme-Hartree-Fock (SHF) approach that have the best fit to the experimental data. When adjusted to reproduce the charge root-mean-square (rms) radius r{sub c} and the rms radii of the valence orbits, the results of the RMF model for the CDEs agree with those of the SHF model within {approx}1%. Our investigation also shows that, although the RMF with the NL3 parameter set reproduces the kink in the isotope variation of r{sub c}, the values obtained for CDEs are too small to account for the experimental values without the addition of the contribution due to long-range correlation effects.

Agrawal, B. K.; Sil, Tapas; Samaddar, S. K.; De, J. N.; Shlomo, S.

2001-08-01

282

6d, Coulomb branch anomaly matching

NASA Astrophysics Data System (ADS)

6d QFTs are constrained by the analog of 't Hooft anomaly matching: all anomalies for global symmetries and metric backgrounds are constants of RG flows, and for all vacua in moduli spaces. We discuss an anomaly matching mechanism for 6d theories on their Coulomb branch. It is a global symmetry analog of Green-Schwarz-West-Sagnotti anomaly cancellation, and requires the apparent anomaly mismatch to be a perfect square, . Then ? I 8 is cancelled by making X 4 an electric/magnetic source for the tensor multiplet, so background gauge field instantons yield charged strings. This requires the coefficients in X 4 to be integrally quantized. We illustrate this for theories. We also consider the SCFTs from N small E8 instantons, verifying that the recent result for its anomaly polynomial fits with the anomaly matching mechanism.

Intriligator, Kenneth

2014-10-01

283

The ghost propagator in Coulomb gauge

NASA Astrophysics Data System (ADS)

We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until `forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

Watson, P.; Reinhardt, H.

2011-05-01

284

Coulomb drag between helical edge states

NASA Astrophysics Data System (ADS)

We theoretically investigate the Coulomb drag between the edge states of two quantum spin Hall systems. Using an interacting theory of the one-dimensional helical edge modes, we show that the drag vanishes at second order in the inter-edge interaction, where it is typically finite in other systems, due to the absence of backscattering within the edges. However, in the presence of a small external magnetic field, the drag is finite and scales as the fourth power of the magnetic field, a behavior that sharply distinguishes it from other systems. We obtain the temperature dependence of the drag for regimes of both linear and quadratic edge dispersion in the presence of a finite field. This work was financially supported by ARO under Grant No. W911NF-09-1-0527. V. A. Zyuzin and G. A. Fiete, Phys. Rev. B 82, 113305 (2010).

Zyuzin, Vladimir; Fiete, Gregory

2011-03-01

285

The quasilinearization method (QLM) is used to approximate analytically, both the ground state and the excited state solutions of the Schrödinger equation for arbitrary potentials. The procedure of approximation was demonstrated on examples of a few often used physical potentials such as the quartic anharmonic oscillator, the Yukawa and the spiked harmonic oscillator potentials. The accurate analytic expressions for the

E. Z. Liverts; V. B. Mandelzweig

2008-01-01

286

We study a lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model, in particular, obeying a Ginsparg-Wilson version of the underlying SU(2) x U(1) symmetry, being a global symmetry here due to the neglection of gauge fields in this model. In this paper we present our results on the cutoff-dependent upper Higgs boson mass bound at several selected values of the cutoff parameter.

P. Gerhold; K. Jansen

2009-12-02

287

Top Yukawa coupling measurement with indefinite CP Higgs in $e^+e^-\\to t\\bar{t}?$

We consider the issue of the top quark Yukawa coupling measurement in a model in dependent and general case with the inclusion of CP-violation in the coupling. Arguably the best process to study this coupling is the associa ted production of Higgs boson along with a $t\\bar t$ pair in a machine like the International Linear Collider (ILC). While detailed analyses of the sensitivity of the measurement assuming a Standard Model (SM) - like coupling are available in the context of ILC, conclude that th e coupling could be pinned down at about 10\\% level with modest luminosity, our investigations show that the scenario could be different in case of a more general coupling. The modified Lorentz structure resulting in a changed functional dependence of the cross section on the couplin g, along with the difference in the cross section itself leads to considerable deviation in the sensitivity. Our studies with an ILC of center of mass energies of 500 GeV, 800 GeV and 1000 GeV show that moderate CP-mixing in the Higgs sector could change the sensitivity to about 20\\ %, while it could be worsened to 75\\% in cases which could accommodate more dramatic changes in the coupling. While detailed considerations of the decay distributions point to a need for a relook at the analysis strategy followed for the case of SM such as for a model independent analysis of the top quark Yukawa coupling measurement. This study strongly suggests that, a joint analysis of the CP properties and the Yukawa coupling measurement would be the way forward at the ILC and that caution must be excercised in the measurem ent of the Yukawa couplings and the conclusions drawn from it.

B. Ananthanarayan; Sumit K. Garg; C. S. Kim; Jayita Lahiri; P. Poulose

2014-05-26

288

Sparticle masses from transverse mass kinks at the LHC: the case of Yukawa-unified SUSY GUTs

We explore, in a concrete example, to which extent new particle mass determinations are practicable with LHC data. Our chosen\\u000a example is that of Yukawa-unified SUSY GUTs, whose viability has been recently studied for two general patterns of soft SUSY-breaking\\u000a terms. We note that both patterns of SUSY spectra do not admit long decay chains, which would make it possible

Kiwoon Choi; Diego Guadagnoli; Sang Hui Im; Chan Beom Park

2010-01-01

289

Scattering and stopping of swift diatomic molecules under Coulomb explosion

The scattering and stopping of the fragments of a fast diatomic molecule under Coulomb explosion has been analyzed theoretically. The central assumption in the scheme is the dominance of Coulomb explosion, while electronic stopping (including wake forces) and elastic scattering are treated as perturbations. Charge exchange has been neglected. Coulomb images of penetration phenomena are heavily distorted. For small penetrated layer thicknesses, images appear contracted in the direction of the molecular axis, and expanded perpendicular to it. This distortion is described quantitatively by a linear transformation. General expressions have been derived for the effect of continuous and stochastic forces on the distribution of fragment velocities from Coulomb explosion (the ring pattern''). Moreover, relations have been found that allow to scale velocity distributions valid in the absence of Coulomb explosion into distributions allowing for Coulomb explosion. Applications concern the shift in ring pattern due to electronic stopping, the lateral broadening due to multiple scattering and the effect of zero-point motion on the Coulomb image of a molecule. 14 refs., 5 figs.

Sigmund, P. (Odense Univ. (Denmark). Dept. of Physics Argonne National Lab., IL (United States))

1991-01-01

290

We report stronger constraints on the parameters of Yukawa-type corrections to Newtonian gravity from measurements of the lateral Casimir force between sinusoidally corrugated surfaces of a sphere and a plate. In the interaction range from 1.6 to 14 nm the strengthening of previously known high confidence constraints up to a factor of 2.4x10{sup 7} is achieved using these measurements. It is shown that the replacement of a plane plate with a corrugated one in the measurements of the normal Casimir force by means of an atomic force microscope would result in the strengthening of respective high confidence constraints on the Yukawa-type interaction by a factor of 1.1x10{sup 12}. The use of a corrugated plate instead of a plane plate in the experiment by means of a micromachined oscillator also leads to strengthening of the obtained constraints. We further obtain constraints on the parameters of Yukawa-type interaction from the data of experiments measuring the gradient of the Casimir pressure between two parallel plates and the gradient of the Casimir-Polder force between an atom and a plate. The obtained results are compared with the previously known constraints. The possibilities of how to further strengthen the constraints on non-Newtonian gravity are discussed.

Bezerra, V. B.; Romero, C. [Department of Physics, Federal University of Paraiba, Caixa Postal 5008, CEP 58059-970, Joao Pessoa, Paraiba (Brazil); Klimchitskaya, G. L. [North-West Technical University, Millionnaya Street 5, St. Petersburg, 191065 (Russian Federation); Mostepanenko, V. M. [Noncommercial Partnership 'Scientific Instruments', Tverskaya Street 11, Moscow, 103905 (Russian Federation)

2010-03-01

291

Antilocalization of Coulomb Blockade in a Ge/Si Nanowire

NASA Astrophysics Data System (ADS)

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 height distribution has its maximum away from zero at zero magnetic field, with an average that decreases with increasing field. Magnetoconductance in the open-wire regime places a bound on the spin-orbit length (lso<20 nm), consistent with values extracted in the Coulomb blockade regime (lso<25 nm).

Higginbotham, A. P.; Kuemmeth, F.; Larsen, T. W.; Fitzpatrick, M.; Yao, J.; Yan, H.; Lieber, C. M.; Marcus, C. M.

2014-05-01

292

Localizing gauge fields on a topological Abelian string and the Coulomb law

The confinement of electromagnetic field is studied in axial symmetrical, warped, six-dimensional brane world, using a recently proposed topological Abelian string-vortex solution as background. It was found, that the massless gauge field fluctuations follow four-dimensional Maxwell equations in the Lorenz gauge. The massless zero mode is localized when the thickness of the string vortex is less than 5{beta}/4{pi}e{sup 2}v{sup 2} and there are no other localized massless modes. There is also an infinite of nonlocalized massive Fourier modes, that follow four-dimensional Proca equations with a continuous spectrum. To compute the corrections to the Coulomb potential, a radial cutoff was introduced, in order to achieve a discrete mass spectrum. As a main result, a (R{sub o}/{beta}R{sup 2}) correction was found for the four-dimensional effective Coulomb law; the result is in correspondence with the observed behavior of the Coulomb potential at today's measurable distances.

Torrealba S, Rafael S. [Departamento de Fisica., Universidad Centro Occidental 'Lisandro Alvarado' (Venezuela, Bolivarian Republic of)

2010-07-15

293

Off-diagonal Yukawa Couplings in the s-channel Charged Higgs Production at LHC

The search for the heavy charged Higgs (mH+ > mtop) has been mainly based on the o?ff-shell top pair production process. However, resonance production in s-channel single top events is an important channel to search for this particle. In a previous work, it was shown that this process, i.e., qq' -> H+ -> tb + h.c., can lead to comparable results to what is already obtained from LHC searches through gb -> tH- process. What was obtained was, however, based on diagonal Yukawa couplings between incoming quarks assuming cs as the main incoming pair due to the CKM matrix element being close to unity. The aim of this paper is to show that off-diagonal couplings, like cb, may lead to substantial contributions to the cross section, even if the corresponding CKM matrix element is two orders of magnitude smaller. For this reason, the cross section is calculated for each initial state including all diagonal and off-diagonal terms, and all is finally added together to get the total cross section which is observed to be ~ 2.7 times larger than what is obtained from cs initial state. Results are eventually re?flected into 95% C.L. exclusion and 5?sigma discovery contours at di?fferent integrated luminosities of LHC. A reasonable coverage of the parameter space is obtained by the 95% C.L. exclusion contour.

Majid Hashemi; Hossein Bakhshalizadeh

2014-07-13

294

Mach cone shocks in a two-dimensional Yukawa solid using a complex plasma

NASA Astrophysics Data System (ADS)

Mach cones were studied experimentally in a two-dimensional Yukawa solid consisting of charged micrometer particles suspended as a layer in a plasma. These cones were V-shaped shocks produced spontaneously by a supersonic particle moving below the main two-dimensional particle layer. The cones had a double structure. The first cone was compressional and particles moved forward, and it was followed by a second cone, which was rarefactional, where particles moved backward. Over the limited range of speed V attained by the supersonic particles in this experiment, the angle ? of the cone was found to obey the Mach cone rule sin ?=c/V, where c is the medium's sound speed. The cones caused only elastic deformations in the crystal lattice, except in a narrow track behind the cone's vertex. The wings of the cones can be analyzed as linear shocks in two dimensions. Using spatially resolved measurements of the particle number density and velocity and applying the Hugoniot relations for shocks in two dimensions, we found that the pressure inside the first Mach cone was greater than in the undisturbed medium by a factor of 1.3-1.6. The cone angle was also used to measure the charge in this experiment.

Samsonov, D.; Goree, J.; Thomas, H. M.; Morfill, G. E.

2000-05-01

295

Freezing lines of colloidal Yukawa spheres. II. Local structure and characteristic lengths

NASA Astrophysics Data System (ADS)

Using the Rogers-Young (RY) integral equation scheme for the static pair correlation functions combined with the liquid-phase Hansen-Verlet freezing rule, we study the generic behavior of the radial distribution function and static structure factor of monodisperse charge-stabilized suspensions with Yukawa-type repulsive particle interactions at freezing. In a related article, labeled Paper I [J. Gapinski, G. Nägele, and A. Patkowski, J. Chem. Phys. 136, 024507 (2012)], this hybrid method was used to determine two-parameter freezing lines for experimentally controllable parameters, characteristic of suspensions of charged silica spheres in dimethylformamide. A universal scaling of the RY radial distribution function maximum is shown to apply to the liquid-bcc and liquid-fcc segments of the universal freezing line. A thorough analysis is made of the behavior of characteristic distances and wavenumbers, next-neighbor particle coordination numbers, osmotic compressibility factor, and the Ravaché-Mountain-Streett minimum-maximum radial distribution function ratio.

Gapinski, Jacek; Nägele, Gerhard; Patkowski, Adam

2014-09-01

296

Freezing lines of colloidal Yukawa spheres. II. Local structure and characteristic lengths.

Using the Rogers-Young (RY) integral equation scheme for the static pair correlation functions combined with the liquid-phase Hansen-Verlet freezing rule, we study the generic behavior of the radial distribution function and static structure factor of monodisperse charge-stabilized suspensions with Yukawa-type repulsive particle interactions at freezing. In a related article, labeled Paper I [J. Gapinski, G. Nägele, and A. Patkowski, J. Chem. Phys. 136, 024507 (2012)], this hybrid method was used to determine two-parameter freezing lines for experimentally controllable parameters, characteristic of suspensions of charged silica spheres in dimethylformamide. A universal scaling of the RY radial distribution function maximum is shown to apply to the liquid-bcc and liquid-fcc segments of the universal freezing line. A thorough analysis is made of the behavior of characteristic distances and wavenumbers, next-neighbor particle coordination numbers, osmotic compressibility factor, and the Ravaché-Mountain-Streett minimum-maximum radial distribution function ratio. PMID:25273449

Gapinski, Jacek; Nägele, Gerhard; Patkowski, Adam

2014-09-28

297

Mach cone shocks in a two-dimensional Yukawa solid using a complex plasma

Mach cones were studied experimentally in a two-dimensional Yukawa solid consisting of charged micrometer particles suspended as a layer in a plasma. These cones were V-shaped shocks produced spontaneously by a supersonic particle moving below the main two-dimensional particle layer. The cones had a double structure. The first cone was compressional and particles moved forward, and it was followed by a second cone, which was rarefactional, where particles moved backward. Over the limited range of speed V attained by the supersonic particles in this experiment, the angle mu of the cone was found to obey the Mach cone rule sin mu = c/V, where c is the medium's sound speed. The cones caused only elastic deformations in the crystal lattice, except in a narrow track behind the cone's vertex. The wings of the cones can be analyzed as linear shocks in two dimensions. Using spatially resolved measurements of the particle number density and velocity and applying the Hugoniot relations for shocks in two dimensions, we found that the pressure inside the first Mach cone was greater than in the undisturbed medium by a factor of 1.3-1.6. The cone angle was also used to measure the charge in this experiment. PMID:11031610

Samsonov; Goree; Thomas; Morfill

2000-05-01

298

The role of E1-E2 interplay in multiphonon Coulomb excitation

In this work we study the problem of a charged particle, bound in a harmonic-oscillator potential, being excited by the Coulomb field from a fast charged projectile. Based on a classical solution to the problem and using the squeezed-state formalism we are able to treat exactly both dipole and quadrupole Coulomb field components. Addressing various transition amplitudes and processes of multiphonon excitation we study different aspects resulting from the interplay between E1 and E2 fields, ranging from classical dynamic polarization effects to questions of quantum interference. We compare exact calculations with approximate methods. Results of this work and the formalism we present can be useful in studies of nuclear reaction physics and in atomic stopping theory.

Alexander Volya; Henning Esbensen

2003-01-19

299

Fast elliptic solvers in cylindrical coordinates and the Coulomb collision operator

Highlights: {yields} We describe new fast solvers for elliptic partial differential equations in free space. {yields} We combine integral equation methods with Fourier methods to achieve high order accuracy. {yields} We apply these solvers to the evaluation of the Coulomb collision operator in plasma physics. - Abstract: In this paper, we describe a new class of fast solvers for separable elliptic partial differential equations in cylindrical coordinates (r, {theta}, z) with free-space radiation conditions. By combining integral equation methods in the radial variable r with Fourier methods in {theta} and z, we show that high-order accuracy can be achieved in both the governing potential and its derivatives. A weak singularity arises in the Fourier transform with respect to z that is handled with special purpose quadratures. We show how these solvers can be applied to the evaluation of the Coulomb collision operator in kinetic models of ionized gases.

Pataki, Andras [Courant Institute, New York University, 251 Mercer Street, NY 10012 (United States); Greengard, Leslie, E-mail: greengard@cims.nyu.edu [Courant Institute, New York University, 251 Mercer Street, NY 10012 (United States)

2011-09-01

300

Eikonal analysis of Coulomb distortion in quasi-elastic electron scattering

An eikonal expansion is used to provide systematic corrections to the eikonal approximation through order $1/k^2$, where $k$ is the wave number. Electron wave functions are obtained for the Dirac equation with a Coulomb potential. They are used to investigate distorted-wave matrix elements for quasi-elastic electron scattering from a nucleus. A form of effective-momentum approximation is obtained using trajectory-dependent eikonal phases and focusing factors. Fixing the Coulomb distortion effects at the center of the nucleus, the often-used ema approximation is recovered. Comparisons of these approximations are made with full calculations using the electron eikonal wave functions. The ema results are found to agree well with the full calculations.

J. A. Tjon; S. J. Wallace

2008-05-28

301

NASA Astrophysics Data System (ADS)

Electro-optic (EO) detection of relativistic Coulomb fields offers a method for non-destructive longitudinal profile measurements of ultrashort bunches. Techniques for single-shot EO characterisation of Coulomb fields which have been developed or demonstrated at the FELIX free electron laser (FEL) facility are discussed. In addition, recent FELIX experiments have used single-shot electro-optic detection to measure the temporal profile of the far-infrared electric field pulse of coherent synchrotron radiation (CSR), initial results of which are reported here. Such time-resolved CSR measurements have the potential for a completely non-invasive bunch longitudinal profile determination, without the ambiguity in profile that is present in CSR spectral measurements.

Jamison, S. P.; Berden, G.; MacLeod, A. M.; Jaroszynski, D. A.; Redlich, B.; van der Meer, A. F. G.; Gillespie, W. A.

2006-02-01

302

Nonequilibrium relaxation and aging scaling of the Coulomb and Bose glass

NASA Astrophysics Data System (ADS)

We employ Monte Carlo simulations to investigate the nonequilibrium relaxation properties of the two- and three-dimensional Coulomb glass with different long-range repulsive interactions. Specifically, we explore the aging scaling laws in the two-time density autocorrelation function. We find that, in the time window and parameter range accessible to us, the scaling exponents are not universal, depending on the filling fraction and temperature: As either the temperature decreases or the filling fraction deviates more from half filling, the exponents reflect markedly slower relaxation kinetics. In comparison with a repulsive Coulomb potential, appropriate for impurity states in strongly disordered semiconductors, we observe that, for logarithmic interactions, the soft pseudogap in the density of states is considerably broader, and the dependence of the scaling exponents on external parameters is much weaker. The latter situation is relevant for flux creep in the disorder-dominated Bose glass phase of type-II superconductors subject to columnar pinning centers.

Shimer, Matthew T.; Täuber, Uwe C.; Pleimling, Michel

2014-09-01

303

NASA Astrophysics Data System (ADS)

We present the study of the quantum tunneling through a vertical two-barrier structure sandwiching a graphene nanoribbon quantum object. Scanning tunneling microscopy measurements of the graphene nanoribbon show staircase I-U characteristics and oscillating dI/dU spectra. To identify the physical origin of the observed effect, we varied the tunneling resistance of the tip-ribbon junction and found a tip-to-ribbon distance dependent oscillating period change. Together with the numerical analysis, we confirm that the resonances in the spectroscopy arise from the Coulomb blockade effect. The study of the Coulomb blockade effect in graphene nanoribbons may be of potential usages for the fabrication of superthin quantum dot devices.

Zhong, Z. F.; Shen, H. L.; Cao, R. X.; Sun, L.; Li, K. P.; Hu, J.; Liu, Z.; Wu, D.; Wang, X. R.; Ding, H. F.

2013-09-01

304

Coulomb excitation of {sup 73}Ga

The B(E2;I{sub i}{yields}I{sub f}) values for transitions in {sub 31}{sup 71}Ga{sub 40} and {sub 31}{sup 73}Ga{sub 42} were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of {sup 71,73}Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted {gamma} rays were detected by the MINIBALL {gamma}-detector array, and B(E2;I{sub i}{yields}I{sub f}) values were obtained from the yields normalized to the known strength of the 2{sup +}{yields}0{sup +} transition in the {sup 120}Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity toward lower excitation energy when adding neutrons beyond N=40. This supports conclusions from previous studies of the gallium isotopes, which indicated a structural change in this isotopic chain between N=40 and 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2{sup -} spin and parity for the ground state, the extracted results revealed evidence for a 1/2{sup -},3/2{sup -} doublet near the ground state in {sub 31}{sup 73}Ga{sub 42} differing by at most 0.8 keV in energy.

Diriken, J.; Bree, N.; Cocolios, T. E.; Huyse, M.; Ivanov, O. V.; Patronis, N.; Pauwels, D.; Van Duppen, P. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Stefanescu, I. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742 (United States); Balabanski, D. [Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy); INRNE, Bulgarian Academy of Science, BG-1784 Sofia (Bulgaria); Blasi, N.; Lo Bianco, G. [Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy); Blazhev, A.; Eberth, J.; Jolie, J.; Reiter, P.; Warr, N. [IKP, University of Cologne, D-50937 Cologne (Germany); Cederkaell, J. [ISOLDE, CERN, CH-1211 Geneva 23 (Switzerland); Physics Department, University of Lund, Box-118, SE-22100 Lund (Sweden); Davinson, T. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Ekstroem, A. [Physics Department, University of Lund, Box-118, SE-22100 Lund (Sweden)

2010-12-15

305

Effective Coulomb interaction in multiorbital system

NASA Astrophysics Data System (ADS)

Transition metal atom generally takes various valences, and sometimes there are some 'missing valences', for example Fe usually takes 2+, 3+ and 5+, but does not take other valences so often. We have calculated the atomic multiplet energies for the high-spin and lowspin configurations within the ligand-field theory and the Hartree-Fock approximation, and found that the Coulomb interaction energy (Ueff) becomes small when the valence is 'missing'. In case Ueff < 0, this valence is not stable and segregates to other valences, and if the system is metallic, this cation site behaves as an attractive center between two conduction electrons. This result might explain one of the mystery of the iron-pnictide superconductor, e.g. the LDA+U approach can reproduce the experimental magnetic moment ~ 0.3?B/Fe only when U < 0 is adopted. We have also investigated the effect of the distortion with symmetry lower than the regular octahedron. We have found that the value of Ueff increased in most cases, but in some special cases Ueff decreases and falls below the value U - 3J, which is the least value of the undistorted system.

Hase, Izumi; Yanagisawa, Takashi

2013-04-01

306

Multilevel Monte Carlo simulation of Coulomb collisions

NASA Astrophysics Data System (ADS)

We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau-Fokker-Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ?, the computational cost of the method is O(?-2) or O(?-2(), depending on the underlying discretization, Milstein or Euler-Maruyama respectively. This is to be contrasted with a cost of O(?-3) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ?=10-5. We discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.

Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; Caflisch, R. E.; Cohen, B. I.

2014-10-01

307

Nuclear Fusion induced by Coulomb Explosion of Heteronuclear Clusters

We propose a new mechanism for the production of high-energy ( E>3 keV) deuterons, suitable to induce dd nuclear fusion, based on multielectron ionization and Coulomb explosion of heteronuclear deuterium containing molecular clusters, e.g., (D2O)n, in intense ( 1016-2×1018 W\\/cm2) laser fields. Cluster size equations for E, in conjunction with molecular dynamics simulations, reveal important advantages of Coulomb explosion of

Isidore Last; Joshua Jortner

2001-01-01

308

Analysis and results of the 104Sn Coulomb excitation experiment

NASA Astrophysics Data System (ADS)

The analysis of the Coulomb excitation experiment conducted on 104Sn required a strict selection of the data in order to reduce the large background present in the ?-ray energy spectra and identify the ?-ray peak corresponding to the Coulomb excitation events. As a result the B(E2; 0+ ? 2+) value could be extracted, which established the downward trend towards 100Sn and therefore the robustness of the N=Z=50 core against quadrupole excitations.

Guastalla, G.; DiJulio, D. D.; Górska, M.; Cederkäll, J.; Boutachkov, P.; Golubev, P.; Pietri, S.; Grawe, H.; Nowacki, F.; Algora, A.; Ameil, F.; Arici, T.; Atac, A.; Bentley, M. A.; Blazhev, A.; Bloor, D.; Brambilla, S.; Braun, N.; Camera, F.; Domingo Pardo, C.; Estrade, A.; Farinon, F.; Gerl, J.; Goel, N.; Gr?bosz, J.; Habermann, T.; Hoischen, R.; Jansson, K.; Jolie, J.; Jungclaus, A.; Kojouharov, I.; Knoebel, R.; Kumar, R.; Kurcewicz, J.; Kurz, N.; Lalovi?, N.; Merchan, E.; Moschner, K.; Naqvi, F.; Nara Singh, B. S.; Nyberg, J.; Nociforo, C.; Obertelli, A.; Pfützner, M.; Pietralla, N.; Podolyák, Z.; Prochazka, A.; Ralet, D.; Reiter, P.; Rudolph, D.; Schaffner, H.; Schirru, F.; Scruton, L.; Swaleh, T.; Taprogge, J.; Wadsworth, R.; Warr, N.; Weick, H.; Wendt, A.; Wieland, O.; Winfield, J. S.; Wollersheim, H. J.

2014-09-01

309

Causality, the Coulomb field, and Newton's law of gravitation

Causality in classical field theories must be inserted by hand by choosing the retarded solution. It is shown how apparent contradictions in the Coulomb gauge can be resolved and that a causal Coulomb field exists despite the appearance to the contrary. Similarly, it is shown how Newtonian gravitation leads from action-at-a-distance to a causal field when a first-order correction for

F. Rohrlich

2002-01-01

310

Diffusion and Coulomb separation of ions in dense matter.

We analyze diffusion equations in strongly coupled Coulomb mixtures of ions in dense stellar matter. Strong coupling of ions in the presence of gravitational forces and electric fields (induced by plasma polarization in the presence of gravity) produces a specific diffusion current which can separate ions with the same A/Z (mass to charge number) ratios but different Z. This Coulomb separation of ions can be important for the evolution of white dwarfs and neutron stars. PMID:24182248

Beznogov, M V; Yakovlev, D G

2013-10-18

311

Relativistic semiclassical theory of the Coulomb excitation of atoms

The processes of Coulomb excitation and ionization of atoms by fast charged particles moving along classical trajectories are considered. The target electrons are described by the Dirac equation and the field of the incoming particle is described by the Lienard-Wiechert potential. The theory is formulated in a form most convenient for the description of all the characteristics of semiclassical atomic collisions. Analytic expressions are obtained in the cases of small and large momentum transfers for K-shell ionization cross sections and for the probabilities and cross sections for the 1S/sub 1/2/..-->..2S/sub 1/2/, 1S/sub 1/2/..-->..2P/sub 1/2/, and 2S/sub 1/2/..-->..2P/sub 1/2/ transitions in a heavy hydrogen-like atom. The stimulated multiphoton emission and absorption processes that occur in inelastic scattering of relativistic electrons by light atoms in an external electromagnetic field are considered. Universal relations are derived in the low-frequency approximation for the total cross section for stimulated absorption in all the inelastic channels.

Yudin, G.L.

1982-09-01

312

An effective screened Coulomb interaction in a quasi-one-dimensional system

NASA Astrophysics Data System (ADS)

In this paper, we derive an analytical expression for the screened Coulomb potential between charge carriers in quasi-one-dimensional (Q1D) semiconductor structures. As an application, this potential has been used to investigate the screening effect on the binding energy of a neutral donor (D0) in quantum wires (QWRs). It is found that the screening effect decreases the neutral donor binding energy, and the screening effects are more obvious in wide QWRs than that in narrow ones. Dependence of screening length on temperature and carrier concentration has also been discussed.

Wang, Yan; Miao, Wen-Dan; Zhai, Li-Xue

2014-01-01

313

The equation-transform model for Dirac–Morse problem including Coulomb tensor interaction

The approximate solutions of Dirac equation with Morse potential in the presence of Coulomb-like tensor potential are obtained by using Laplace transform (LT) approach. The energy eigenvalue equation of the Dirac particles is found and some numerical results are obtained. By using convolution integral, the corresponding radial wave functions are presented in terms of confluent hypergeometric functions. -- Highlights: •The Dirac equation with tensor interaction is solved by using Laplace transform. •For solving this equation, we introduce the equation-transform model. •Numerical results and plots for pseudospin and spin symmetric solutions are given. •The obtained numerical results by using transform method are compared with orthogonal polynomial method.

Ortakaya, Sami, E-mail: sami.ortakaya@yahoo.com

2013-11-15

314

Aftershock triggering by complete Coulomb stress changes

We examine the correlation between seismicity rate change following the 1992, M7.3, Landers, California, earthquake and characteristics of the complete Coulomb failure stress (CFS) changes (??CFS(t)) that this earthquake generated. At close distances the time-varying "dynamic" portion of the stress change depends on how the rupture develops temporally and spatially and arises from radiated seismic waves and from permanent coseismic fault displacement. The permanent "static" portion (??CFS) depends only on the final coseismic displacement. ??CFS diminishes much more rapidly with distance than the transient, dynamic stress changes. A common interpretation of the strong correlation between ??CFS and aftershocks is that load changes can advance or delay failure. Stress changes may also promote failure by physically altering properties of the fault or its environs. Because it is transient, ??CFS(t) can alter the failure rate only by the latter means. We calculate both ??CFS and the maximum positive value of ??CFS(t) (peak ??CFS(t)) using a reflectivity program. Input parameters are constrained by modeling Landers displacement seismograms. We quantify the correlation between maps of seismicity rate changes and maps of modeled ??CFS and peak ??CFS(t) and find agreement for both models. However, rupture directivity, which does not affect ??CFS, creates larger peak ??CFS(t) values northwest of the main shock. This asymmetry is also observed in seismicity rate changes but not in ??CFS. This result implies that dynamic stress changes are as effective as static stress changes in triggering aftershocks and may trigger earthquakes long after the waves have passed.

Kilb, D.; Gomberg, J.; Bodin, P.

2002-01-01

315

Nonperturbative Determination of the QCD Potential at O(1\\/m)

The relativistic correction to the QCD static interquark potential at O(1\\/m) is investigated nonperturbatively for the first time by using lattice Monte Carlo QCD simulations. The correction is found to be comparable with the Coulombic term of the static potential when applied to charmonium, and amounts to one-fourth of the Coulombic term for bottomonium.

Yoshiaki Koma; Miho Koma; Hartmut Wittig

2006-01-01

316

Nonperturbative determination of the QCD potential at O(1/m)

The relativistic correction to the QCD static inter-quark potential at O(1/m) is investigated nonperturbatively for the first time by using lattice Monte Carlo QCD simulations. The correction is found to be comparable with the Coulombic term of the static potential when applied to charmonium, and amounts to 26% of the Coulombic term for bottomonium.

Koma, Y; Wittig, H; Koma, Yoshiaki; Koma, Miho; Wittig, Hartmut

2006-01-01

317

Predicting Freezing for Some Repulsive Potentials

We propose a simple method to approximately predict the freezing (fluid-solid) phase transition in systems of particles interacting via purely repulsive potentials. The method is based on the striking universality of the freezing curve for the model Yukawa and inverse-power-law interactions. This method is applied to draw an exemplary phase diagram of complex plasmas. We suggest that it can also be used to locate freezing transition in other substances with similar properties of interaction.

Khrapak, S. A.; Morfill, G. E. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741 Garching (Germany)

2009-12-18

318

Full simulation study of the top Yukawa coupling at the ILC at $\\sqrt{s}$ = 1 TeV

We present a study of the expected precision for measurement of the top Yukawa coupling, yt, in e+e- collisions at a center-of-mass energy of 1 TeV and assuming a beam polarization of P (e-, e+) = (-0.8,+0.2). Independent analyses of ttH final states containing at least six hadronic jets are performed, based on detailed simulations of SiD and ILD, the two candidate detector concepts for the ILC. We estimate that a statistical precision of yt of 4% can be obtained with an integrated luminosity of 1 $\\mathrm{ab}^{-1}$.

Tony Price; Philipp Roloff; Jan Strube; Tomohiko Tanabe

2014-09-25

319

Modified Coulomb-Dipole Theory for 2e Photoionization

NASA Technical Reports Server (NTRS)

In the light of recent experiment on 2e photoionization of Li near threshold, we have considered a modification of the Coulomb-dipole theory, retaining the basic assumption that the threshold is dominated by asymmetric events in phase space [implies r(sub 1), k(sub 1)) greater than or equal to 2(r(sub 2), k(sub )]. In this region [in a collinear model, 2/r(sub 12) approached + 2/(r(sub 1)+r(sub 2)] the interaction reduces to V(rIsub 1) is greater than or equal to 2r(sub 2) is identically equal to [(-Z/r(sub 2)-(A-1)/r(sub 1)] + [(-2r(sub 2)/r(sub 1 exp 2)] is identically equal to V(sub c)+[V(sub d)]. For two electron emission Z = 2, thus both electrons see a Coulomb potential (V(sub c)) asymptotically, albeit each seeing a different charge. The residual potential (V(sub d)) is dipole in character. Writing the total psi = psi (sub c) + psi(sub d) = delta psi, and noting that. (T+V(sub c)-E)psy(sub c) = 0 and (T+V(sub c))psi(sub d) = 0 can be solved exactly, we find, substituting psi into the complete Schrod. Eq., that delta psi = -(H-E)(exp -1)(V(sub d) psi(sub 0)+V(sub c psi (sub 1). Using the fact that the absolute value of V(sub c) is much more than the absolute value of V(sub d) in almost all of configuration space, we can replace H by H(sub 0) in 9H-E)(exp -1) to obtain an improved approximation psi (improved) = psi(sub c) + psi(sub d) -(H(sub 0)-E)(exp -1) (V(sub c) psi (sub 0) + V(sub c) psi(sub 1). Here's the Green's function (H(sub 0)-E)(exp -1), can be exhibited explicitly, but the last term in psi (improved) is small, compared to the first two terms. Inserting them into the transition matrix element, which one handles in the usual way, we obtain in the limit E approaches 0, the threshold law: Q(E) alpha E + M(E)E(exp 5/4) + higher order (Eq. 1a). The modulation function, M(E), is a well-defined (but very non-trivial integral, but it is expected to be well approximated by a sinusoidal function containing a dipole phase term (M(E) = c sin[alpha log (E) + micron] (Eq. 1b). Experimental results show definite modulations, and are well fitted by Eqs (1).

2004-01-01

320

Weak interaction rate Coulomb corrections in big bang nucleosynthesis

We have applied a fully relativistic Coulomb wave correction to the weak reactions in the full Kawano/Wagoner big bang nucleosynthesis (BBN) code. We have also added the zero-temperature radiative correction. We find that using this higher accuracy Coulomb correction results in good agreement with previous work, giving only a modest {approx}0.04% increase in helium mass fraction over correction prescriptions applied previously in BBN calculations. We have calculated the effect of these corrections on other light element abundance yields in BBN, and we have studied these yields as functions of electron neutrino lepton number. This has allowed insights into the role of the weak neutron-proton interconversion processes in the setting of the neutron-to-proton ratio during the BBN epoch. We find that the lepton capture processes' contributions to this ratio are only second order in the Coulomb correction.

Smith, Christel J. [Department of Physics, University of California, San Diego, La Jolla, California 92093-0319 (United States); Physics Department, Arizona State University, Tempe, Arizona, 85287-1504 (United States); Fuller, George M. [Department of Physics, University of California, San Diego, La Jolla, California 92093-0319 (United States)

2010-03-15

321

Coulomb branch Hilbert series and Hall-Littlewood polynomials

NASA Astrophysics Data System (ADS)

There has been a recent progress in understanding the chiral ring of 3d = 4 superconformal gauge theories by explicitly constructing an exact generating function (Hilbert series) counting BPS operators on the Coulomb branch. In this paper we introduce Coulomb branch Hilbert series in the presence of background magnetic charges for flavor symmetries, which are useful for computing the Hilbert series of more general theories through gluing techniques. We find a simple formula of the Hilbert series with background magnetic charges for T ? ( G) theories in terms of Hall-Littlewood polynomials. Here G is a classical group and ? is a certain partition related to the dual group of G. The Hilbert series for vanishing background magnetic charges show that Coulomb branches of T ? ( G) theories are complete intersections. We also demonstrate that mirror symmetry maps background magnetic charges to baryonic charges.

Cremonesi, Stefano; Hanany, Amihay; Mekareeya, Noppadol; Zaffaroni, Alberto

2014-09-01

322

Coulomb branch Hilbert series and Hall-Littlewood polynomials

There has been a recent progress in understanding the chiral ring of 3d $\\mathcal{N}=4$ superconformal gauge theories by explicitly constructing an exact generating function (Hilbert series) counting BPS operators on the Coulomb branch. In this paper we introduce Coulomb branch Hilbert series in the presence of background magnetic charges for flavor symmetries, which are useful for computing the Hilbert series of more general theories through gluing techniques. We find a simple formula of the Hilbert series with background magnetic charges for $T_\\rho(G)$ theories in terms of Hall-Littlewood polynomials. Here $G$ is a classical group and $\\rho$ is a certain partition related to the dual group of $G$. The Hilbert series for vanishing background magnetic charges show that Coulomb branches of $T_\\rho(G)$ theories are complete intersections. We also demonstrate that mirror symmetry maps background magnetic charges to baryonic charges.

Cremonesi, Stefano; Mekareeya, Noppadol; Zaffaroni, Alberto

2014-01-01

323

Coulomb branch Hilbert series and Hall-Littlewood polynomials

There has been a recent progress in understanding the chiral ring of 3d $\\mathcal{N}=4$ superconformal gauge theories by explicitly constructing an exact generating function (Hilbert series) counting BPS operators on the Coulomb branch. In this paper we introduce Coulomb branch Hilbert series in the presence of background magnetic charges for flavor symmetries, which are useful for computing the Hilbert series of more general theories through gluing techniques. We find a simple formula of the Hilbert series with background magnetic charges for $T_\\rho(G)$ theories in terms of Hall-Littlewood polynomials. Here $G$ is a classical group and $\\rho$ is a certain partition related to the dual group of $G$. The Hilbert series for vanishing background magnetic charges show that Coulomb branches of $T_\\rho(G)$ theories are complete intersections. We also demonstrate that mirror symmetry maps background magnetic charges to baryonic charges.

Stefano Cremonesi; Amihay Hanany; Noppadol Mekareeya; Alberto Zaffaroni

2014-03-03

324

Dynamical saddle vs Coulomb saddle in antiproton impact ionization

The slow Coulomb breakup of a bound pair of particles by charged particle impact is often characterized by the Coulomb saddle located between the two like charges. If the breakup includes an antiproton, however, the particles experience forces on the Coulomb saddle and will tend to drift off the saddle, possibly preventing three particle breakup. There is however a dynamical saddle which eliminates these drift forces among the particles as the system breaks up, analogous to the situation in positron impact ionization. In the case of antiproton impact, the authors thus find a dynamical saddle dominated by the proton-antiproton center of mass with the proton between the two negative charges but about six times closer to the antiproton than the electron. They will present a derivation of the resulting Wannier threshold law and consider possible probes of these fundamental saddles with the antiproton replaced by a negative ion.

Goddard, M.; Feagin J.M. [Univ. of California, Fullerton, CA (United States)

1996-05-01

325

The ice-limit of Coulomb gauge Yang-Mills theory

In this paper we describe gauge invariant multi-quark states generalising the path integral framework developed by Parrinello, Jona-Lasinio and Zwanziger to amend the Faddeev-Popov approach. This allows us to produce states such that, in a limit which we call the ice-limit, fermions are dressed with glue exclusively from the fundamental modular region associated with Coulomb gauge. The limit can be taken analytically without difficulties, avoiding the Gribov problem. This is llustrated by an unambiguous construction of gauge invariant mesonic states for which we simulate the static quark--antiquark potential.

Thomas Heinzl; Anton Ilderton; Kurt Langfeld; Martin Lavelle; David McMullan

2008-07-29

326

The E2 contribution to the 8B -> p + 7Be Coulomb dissociation cross section

We have calculated the E1 and E2 contributions to the low-energy B-8 + Pb-208 -> p + Be-7 + Pb-208 Coulomb dissociation cross sections using the kinematics of a recent experiment at RIKEN. Using a potential model description of the Be-7 (p,gamma) B-8 reaction, we find that the E2 contributions cannot a priori be ignored in the analysis of the data. Its inclusion reduces the extracted Be-7 (p,gamma) B-8 S-factor at solar energies by about 25%.

K. Langanke; T. D. Shoppa

1994-02-02

327

On rate-state and Coulomb failure models

We examine the predictions of Coulomb failure stress and rate-state frictional models. We study the change in failure time (clock advance) ?t due to stress step perturbations (i.e., coseismic static stress increases) added to "background" stressing at a constant rate (i.e., tectonic loading) at time t0. The predictability of ?t implies a predictable change in seismicity rate r(t)/r0, testable using earthquake catalogs, where r0 is the constant rate resulting from tectonic stressing. Models of r(t)/r0, consistent with general properties of aftershock sequences, must predict an Omori law seismicity decay rate, a sequence duration that is less than a few percent of the mainshock cycle time and a return directly to the background rate. A Coulomb model requires that a fault remains locked during loading, that failure occur instantaneously, and that ?t is independent of t0. These characteristics imply an instantaneous infinite seismicity rate increase of zero duration. Numerical calculations of r(t)/r0 for different state evolution laws show that aftershocks occur on faults extremely close to failure at the mainshock origin time, that these faults must be "Coulomb-like," and that the slip evolution law can be precluded. Real aftershock population characteristics also may constrain rate-state constitutive parameters; a may be lower than laboratory values, the stiffness may be high, and/or normal stress may be lower than lithostatic. We also compare Coulomb and rate-state models theoretically. Rate-state model fault behavior becomes more Coulomb-like as constitutive parameter a decreases relative to parameter b. This is because the slip initially decelerates, representing an initial healing of fault contacts. The deceleration is more pronounced for smaller a, more closely simulating a locked fault. Even when the rate-state ?t has Coulomb characteristics, its magnitude may differ by some constant dependent on b. In this case, a rate-state model behaves like a modified Coulomb failure model in which the failure stress threshold is lowered due to weakening, increasing the clock advance. The deviation from a non-Coulomb response also depends on the loading rate, elastic stiffness, initial conditions, and assumptions about how state evolves.

Gomberg, J.; Beeler, N.; Blanpied, M.

2000-01-01

328

Lifetime Measurements and Coulomb Excitation of Light Hg Nuclei

Two complementary experimental programs have taken place to investigate the origin and evolution of shape coexistence in the light mercury region. Recoil Distance Doppler-shift measurements were performed at the University of Jyvaeskylae utilizing the Koeln plunger device in conjunction with the JUROGAM+RITU+GREAT setup. In addition, Coulomb excitation measurements of {sup 184,186,188}Hg were performed at REX-ISOLDE using the MINIBALL Ge-detector array. The results of the lifetime measurements of the yrast states up to I{sup {pi}} = 10{sup +} in {sup 182}Hg are reported. Preliminary analysis of the Coulomb excitation data is also discussed.

Petts, A.; Butler, P. A.; Grahn, T.; Herzberg, R.-D.; Page, R. D.; Pakarinen, J.; Scheck, M. [Oliver Lodge Laboratory, Department of Physics, University of Liverpool, Liverpool, L69 7ZE (United Kingdom); Blazhev, A.; Bruyneel, B.; Dewald, A.; Eberth, J.; Fransen, C.; Jolie, J.; Melon, B.; Pascovici, G.; Pissulla, Th.; Reiter, P.; Warr, N.; Weisshaar, D. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Bree, N. [Instituut voor Kern-en Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Leuven (Belgium)] (and others)

2009-01-28

329

Aharonov-Bohm and Coulomb Scattering Near the Forward Direction

The exact wave functions that describe scattering of a charged particle by a confined magnetic field (Aharonov-Bohm effect) and by a Coulomb field are analyzed. It is well known that the usual procedure of finding asymptotic forms of these functions which admit a separation into a superposition of an incident plane wave and a circular or spherical scattered wave is

Charles M. Sommerfield; Hisakazu Minakata

2000-01-01

330

Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

2008-08-22

331

Hamiltonian flow in Coulomb gauge Yang-Mills theory

We derive a new functional renormalization group equation for Hamiltonian Yang-Mills theory in Coulomb gauge. The flow equations for the static gluon and ghost propagators are solved under the assumption of ghost dominance within different diagrammatic approximations. The results are compared to those obtained in the variational approach and the reliability of the approximations is discussed.

Leder, Markus; Reinhardt, Hugo [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, 72076 Tuebingen (Germany); Pawlowski, Jan M. [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Weber, Axel [Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio C-3, Ciudad Universitaria, 58040 Morelia, Michoacan (Mexico)

2011-01-15

332

On Coulomb collisions in bi-Maxwellian plasmas

Collisional momentum and energy transport in bi-Maxwellian plasmas with a drift velocity along the ambient magnetic field are calculated from both the Fokker-Planck and Boltzmann integral approximations. The transport coefficients obtained from the two approaches are identical to the leading order (proportional to the Coulomb logarithm) and are presented here in a closed form involving generalized double hypergeometric functions.

Hellinger, Petr; Travnicek, Pavel M. [Institute of Atmospheric Physics and Astronomical Institute, AS CR, Bocni II/1401, CZ-14131 Prague (Czech Republic)

2009-05-15

333

Doppler cooling of a Coulomb crystal Giovanna Morigi1

the laser wavelength . We find a Fokker-Planck equation for the total mechanical energy of the system, whose-mechanical master equation, an equation for the total mechanical energy of a one-dimensional crystal, definedDoppler cooling of a Coulomb crystal Giovanna Morigi1 and JuÂ¨rgen Eschner2 1 Max-Planck-Institut fu

Blatt, Rainer

334

Coulomb Interactions in Hanbury Brown-Twiss Experiments with Electrons

ERIC Educational Resources Information Center

This dissertation examines the effect of Coulomb interactions in Hanbury Brown-Twiss (HBT) type experiments with electrons. HBT experiments deal with intensity interference, which is related to the second-order correlation function of the particle field. This is an extension of the usual amplitude interference experiment, such as Young's…

Shen, Kan

2009-01-01

335

RIBONUCLEASES AS CANCER AND VIRAL THERAPEUTICS: ROLE OF COULOMBIC INTERACTIONS

inhibitor protein (RI), which binds to members of the RNase A superfamily with extremely high affinity focuses on the role of Coulombic interactions in two of these processes- cellular internalization and RI-infected cells was created from RNase A. Cleavage of this zymogen by HIV protease results in a 50- fold increase

Raines, Ronald T.

336

Coulomb blockade in vertical, bandgap engineered silicon nanopillars

NASA Astrophysics Data System (ADS)

Vertically oriented, bandgap engineered silicon double tunnel junction nanopillars were fabricated and electrically addressed. The devices were tested at liquid nitrogen and room temperatures. Distinctive staircase steps in current were observed at cryogenic temperatures indicative of the Coulomb blockade effect present in asymmetric double tunnel junction structures. These features disappeared when the device was measured at room temperature.

Walavalkar, Sameer; Latawiec, Pawel; Scherer, Axel

2013-05-01

337

LTU Physlet: Coulomb's Law With Multiple Discrete Charges

NSDL National Science Digital Library

This simple applet shows two fixed charges and a moveable test charge. The total Coulomb force on the test charge is displayed. The user can toggle between the fixed charges having like unequal charges or unlike unequal charges. A brief explanation is provided. This is part of a large collection of Physlet-based (Physics Java Applet) illustrations and tutorials covering introductory physics.

Schneider, Scott

2007-06-13

338

On Dirac-Coulomb problem in (2+1) dimensional space-time and path integral quantization

The problem of Dirac particle interacting with Coulomb potential in (2+1) dimensions is formulated in the framework of super-symmetric path integrals where the spin degrees of freedom are described by odd Grassmannian variables. The relative propagator is expressed through Cartesian coordinates in a Hamiltonian form by the use of an adequate transformation. The passage to the polar coordinates permitted us to calculate the fixed energy Green's function and to extract bound states and associating wave functions.

Haouat, S. [L.P.Th, Departement de physique, Universite de Jijel, BP 98, Ouled Aissa, Jijel 18000 (Algeria); Chetouani, L. [Departement de Physique, Faculte de Sciences, Universite Mentouri, Route Ain El-Bey, Constantine 25000 (Algeria)

2012-06-15

339

Weak formulations and solution multiplicity of equilibrium configurations with Coulomb friction

Weak formulations and solution multiplicity of equilibrium configurations with Coulomb friction configurations of elastic struc- tures in contact with Coulomb friction. We obtain a variational formulation configurations with arbitrary small friction coefficients. We illustrate the result in two space dimensions

Bostan, Mihai

340

Symmetries in confined classical Coulomb systems

The properties of charged particles confined in a harmonic oscillator potential have become of increased interest lately in view of the development of techniques in ion traps and storage rings. The symmetries in such systems intrigued the imagination of Ted Hecht in connection with the storage ring at Heidelberg, and so perhaps it is an appropriate subject for this symposium.

Schiffer, J.P.

1991-01-01

341

Compact Collision Kernels for Hard Sphere and Coulomb Cross Sections; Fokker-Planck Coefficients

A compact collision kernel is derived for both hard sphere and Coulomb cross sections. The difference between hard sphere interaction and Coulomb interaction is characterized by a parameter {eta}. With this compact collision kernel, the calculation of Fokker-Planck coefficients can be done for both the Coulomb and hard sphere interactions. The results for arbitrary order Fokker-Planck coefficients are greatly simplified. An alternate form for the Coulomb logarithm is derived with concern to the temperature relaxation in a binary plasma.

Chang Yongbin; Shizgal, Bernie D. [Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada)

2008-12-31

342

Two-dimensional and three-dimensional Coulomb clusters in parabolic traps

NASA Astrophysics Data System (ADS)

We consider the shell structure of Coulomb clusters in an axially symmetric parabolic trap exhibiting a confining potential Uc(? ,z)=(m?2/2)(?2+?z2). Assuming an anisotropic parameter ? = 4 (corresponding to experiments employing a cusp magnetic trap under microgravity conditions), we have calculated cluster configurations for particle numbers N = 3 to 30. We have shown that clusters with N ? 12 initially remain flat, transitioning to three-dimensional configurations as N increases. For N = 8, we have calculated the configurations of minimal potential energy for all values of ? and found the points of configuration transitions. For N = 13 and 23, we discuss the influence of both the shielding and anisotropic parameter on potential energy, cluster size, and shell structure.

D'yachkov, L. G.; Myasnikov, M. I.; Petrov, O. F.; Hyde, T. W.; Kong, J.; Matthews, L.

2014-09-01

343

The relativistic three dimensional (3D) Lippmann-Schwinger-type equations for the $ep$ scattering amplitude is derived based on unitarity condition in the usual quantum electrodynamic (QED). The $ep$ scattering potential $V_{e'N',eN}$ consists of the leading one off mass shell photon exchange part and the nonlocal multi-particle exchange potential. Unlike to the other field-theoretical equations, both protons in the unitarity condition and in $V_{e'N',eN}$ are on mass shell. Therefore in this approach are not required the multi-variable input photon-nucleon vertexes with the off mass shell nucleons. In the present formulation the standard leading one photon exchange potential $V_{OPE}$ is generated by the canonical equal-time anti commutator between the electron source and the interacted electron fields which are sandwiched by the one nucleon asymptotic states. This anticommutator is calculated in the Coulomb and Lorentz gauges, where only the transverse parts of the photon fields are quantized. It is shown, that the leading one photon exchange potentialn$V_{OPE}$ in the Coulomb and Lorentz gauges coincide. The complete set of the next to leading order terms which are generated by the static electric (Coulomb) interaction are exactly reproduced.

A. I. Machavariani

2014-02-23

344

Single-electron tunneling and Coulomb charging effects in ultrasmall double-barrier heterostructures

NASA Astrophysics Data System (ADS)

An extensive study of charge transport through submicron-diameter double barrier heterostructure diodes is reported. The occupation of the quantum well with single electrons, starting from zero, is observed in the form of sharp steps in the current-voltage characteristics. The magnitude of the current steps can be controlled by changing the barrier thicknesses and thus their transparency for tunneling electrons. The plateau width of the current steps is related to the energies of the electron states in the quantum well that are affected by the lateral quantum confinement, and by Coulomb charging effects. Diameter dependent studies of the tunneling current suggest that the lateral quantum confinement can result from the surface depletion potential, potential fluctuations, or single impurities. High magnetic field studies confirm this conclusion. The contribution of the Coulomb charging energy is investigated by using an asymmetric double barrier profile. It is shown that tunneling through submicron-diameter double barrier heterostructures provides valuable insight into the electronic properties of quantum boxes containing a few electrons.

Tewordt, M.; Law, V. J.; Nicholls, J. T.; Martín-Moreno, L.; Ritchie, D. A.; Kelly, M. J.; Pepper, M.; Frost, J. E. F.; Newbury, R.; Jones, G. A. C.

1994-06-01

345

NASA Astrophysics Data System (ADS)

The reactions of a nucleophilic dianion with a series of activated aryl bromides were studied in the gas phase. Nucleophilic aromatic substitution (SNAr) as well as proton transfer reactions were observed. Rate constants and branching ratios were determined for all the reactions and the experimental data are supported by ab initio calculations. Reactions with bis-trifluoromethylbromobenzenes give only SNAr reactions and the rate constants follow the expected pattern, with substituents at the ortho and para positions having the greatest impact. Reactions of polyfluorobromobenzenes give a mix of proton transfer (when possible) and SNAr, with both bromide and fluoride acting as leaving groups. The latter is much less thermodynamically favorable but is the dominant pathway in each case. The selectivity of the reactions indicate that the products are determined early on the potential energy surface, before there is significant cleavage of the bond to the leaving group—the reaction is potentially directed by the initial formation of a hydrogen bond with the arene. The computational data also suggest that hydrogen bonding in the product ion-ion complexes can stabilize the system until there is sufficient charge separation to use the internal Coulomb repulsion to drive the reactions to products. Overall, the results highlight (1) the ability of multiply-charged systems to efficiently funnel their Coulomb repulsion into reaction processes that are intrinsically unfavorable, and (2) the high degree of selectivity that can be attained even in systems with multiple, low-barrier pathways.

Eanes, Allison D.; Noin, Diogo O.; Kebede, Maheteme K.; Gronert, Scott

2014-01-01

346

The effect of the Coulomb field on the oriented gas approximation

The oriented gas approximation for the polarizability of a molecular crystal neglects the Coulomb field of induced dipoles throughout the crystal. This would at first appear to be a serious shortcoming since the Coulomb field is of the same order as the applied field. The oriented gas model is extended by including the Coulomb field and draw a comparison to

J. W. Arthur

1976-01-01

347

A new approach for efficient simulation of Coulomb interactions in ionic fluids

We propose a simplified version of local molecular field (LMF) theory to treat Coulomb interactions in simulations of ionic fluids. LMF theory relies on splitting the Coulomb potential into a short-ranged part that combines with other short-ranged core interactions and is simulated explicitly. The averaged effects of the remaining long-ranged part are taken into account through a self-consistently determined effective external field. The theory contains an adjustable length parameter sigma that specifies the cut-off distance for the short-ranged interaction. This can be chosen to minimize the errors resulting from the mean-field treatment of the complementary long-ranged part. Here we suggest that in many cases an accurate approximation to the effective field can be obtained directly from the equilibrium charge density given by the Debye theory of screening, thus eliminating the need for a self-consistent treatment. In the limit sigma -> 0, this assumption reduces to the classical Debye approximation. We examine the numerical performance of this approximation for a simple model of a symmetric ionic mixture. Our results for thermodynamic and structural properties of uniform ionic mixtures agree well with similar results of Ewald simulations of the full ionic system. In addition we have used the simplified theory in a grand-canonical simulation of a nonuniform ionic mixture where an ion has been fixed at the origin. Simulations using short-ranged truncations of the Coulomb interactions alone do not satisfy the exact condition of complete screening of the fixed ion, but this condition is recovered when the effective field is taken into account. We argue that this simplified approach can also be used in the simulations of more complex nonuniform systems.

Natalia A. Denesyuk; John D. Weeks

2008-02-21

348

Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q {approx} 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement.

Cleland, A.N.

1991-04-01

349

Algebraic treatment of the confluent Natanzon potentials

Using the so(2,1) Lie algebra and the Baker, Campbell and Hausdorff formulas, the Green's function for the class of the confluent Natanzon potentials is constructed straightforwardly. The bound-state energy spectrum is then determined. Eventually, the three-dimensional harmonic potential, the three-dimensional Coulomb potential and the Morse potential may all be considered as particular cases.

Chefrour, M T; Guechi, L

2000-01-01

350

Algebraic treatment of the confluent Natanzon potentials

Using the so(2,1) Lie algebra and the Baker, Campbell and Hausdorff formulas, the Green's function for the class of the confluent Natanzon potentials is constructed straightforwardly. The bound-state energy spectrum is then determined. Eventually, the three-dimensional harmonic potential, the three-dimensional Coulomb potential and the Morse potential may all be considered as particular cases.

M. T. Chefrour; L. Chetouani; L. Guechi

2002-01-05

351

Higgs boson masses and mixings in the complex MSSM with two-loop top-Yukawa-coupling corrections

NASA Astrophysics Data System (ADS)

Results for the leading two-loop corrections of from the Yukawa sector to the Higgs-boson mass spectrum of the MSSM with complex parameters are presented, with details of the analytical calculation performed in the Feynman-diagrammatic approach using a mixed on-shell/ scheme that can be directly matched onto the higher-order terms in the code FeynHiggs. Numerical results are shown for the masses and mixing effects in the neutral Higgs-boson sector and their variation with the phases of the complex parameters. Furthermore, the analytical expressions of the two-loop self-energies and the required renormalization constants are recorded. The new results can consistently be implemented in FeynHiggs.

Hollik, Wolfgang; Paßehr, Sebastian

2014-10-01

352

NASA Astrophysics Data System (ADS)

Using a generalized hydrodynamic (GH) model, the growth rate spectra of Kelvin-Helmholtz (KH) instability has been obtained analytically for a step shear profile in strongly coupled Yukawa liquids. The class of shear flows studied is assumed to be incompressible in nature. The growth rate spectra calculated exhibit viscous damping at high mode numbers, destabilization at stronger coupling, and in the limit ?m (viscoelastic relaxation time)?0, reduce to the regular Navier-Stokes growth rate spectra. A direct comparison is made with previous molecular dynamics (MD) simulations [Ashwin J. and R. Ganesh, Phys. Rev. Lett. 104, 215003 (2010)] of KH instability. We find that for a given value of Reynolds number R and coupling parameter 1

Ashwin, J.; Ganesh, R.

2010-10-01

353

Using a generalized hydrodynamic (GH) model, the growth rate spectra of Kelvin-Helmholtz (KH) instability has been obtained analytically for a step shear profile in strongly coupled Yukawa liquids. The class of shear flows studied is assumed to be incompressible in nature. The growth rate spectra calculated exhibit viscous damping at high mode numbers, destabilization at stronger coupling, and in the limit {tau}{sub m} (viscoelastic relaxation time){yields}0, reduce to the regular Navier-Stokes growth rate spectra. A direct comparison is made with previous molecular dynamics (MD) simulations [Ashwin J. and R. Ganesh, Phys. Rev. Lett. 104, 215003 (2010)] of KH instability. We find that for a given value of Reynolds number R and coupling parameter 1<{Gamma}<100, the GH and MD growth rates are in a qualitative agreement. The inclusion of the effect of shear heating as an effective coupling parameter {Gamma}{sub e} appears to improve the quantitative comparison as well.

Ashwin, J.; Ganesh, R. [Institute For Plasma Research, Bhat, Gandhinagar 382428 (India)

2010-10-15

354

In the type I + II seesaw formula the mass matrix of light neutrinos m_nu receives contributions from the exchanges of both heavy Majorana neutrinos and SU(2)_L-triplet Higgs bosons. We propose a new parameterization for the Dirac-type Yukawa coupling matrix of neutrinos in this case, which generalizes the well known Casas-Ibarra parameterization to type I + II seesaw and is useful when the triplet term in m_nu is known. Neutrino masses and mixing, lepton flavor violation in decays like mu -> e \\gamma within mSUGRA models and leptogenesis can then be studied within this framework. We illustrate the usefulness of our new parameterization using a number of simple examples.

Evgeny Kh. Akhmedov; Werner Rodejohann

2008-03-17

355

NASA Astrophysics Data System (ADS)

Using a generalized hydrodynamic (GH) model, the growth rate spectra of Kelvin-Helmholtz (KH) instability has been obtained analytically for a step shear profile in strongly coupled Yukawa liquids. The class of shear flows studied is assumed to be incompressible in nature. The growth rate spectra calculated exhibit viscous damping at high mode numbers, destabilization at stronger coupling, and in the limit ?m (viscoelastic relaxation time)-->0, reduce to the regular Navier-Stokes growth rate spectra. A direct comparison is made with previous molecular dynamics (MD) simulations [Ashwin J. and R. Ganesh, Phys. Rev. Lett. 104, 215003 (2010)] of KH instability. We find that for a given value of Reynolds number R and coupling parameter 1

Ashwin, J.; Ganesh, R.

2010-10-01

356

NASA Astrophysics Data System (ADS)

The influence of a high-intensity laser field on the Coulomb explosion and stopping power for a swift C60 cluster ion in a plasma target is studied by means of the molecular dynamics method based on the linearized Vlasov-Poisson theory. In the presence of the laser field, the general expressions for the induced potential in the target among the ions within the cluster are derived. Based on the numerical solution of the equations of motion for the constituent ions, the Coulomb explosion patterns and the cluster's stopping power are discussed for a range of laser and plasma parameters. Numerical results show that the laser field affects the correlation between the ions and contributes to weakening the wake effect and the stopping power as compared to the laser-free case. On the other hand, the vicinage effects in the cluster Coulomb explosion dynamics and the stopping power are strongly affected by the variations in the laser parameters, cluster speed, and plasma parameters. For example, Coulomb explosions are found to be hindered in the longitudinal expansion with the increasing of laser intensity and laser angle, and the Coulomb explosions proceed faster for lower plasma densities and higher electron temperatures.

Wang, Gui-Qiu; E, Peng; Ma, Tao; Wang, You-Nian; Yao, Li; Wang, Yao-Chuan; Liu, Da-Jun; Gao, Hong; Hu, Zhang-Hu; Duan, Fang-Shuai; Zhong, Hai-Yang; Cheng, Li-Hong; Yang, Kun; Liu, Wei; Sun, Min; Xu, Dian-Guo

2012-10-01

357

It is shown that on curved backgrounds, the Coulomb gauge Faddeev-Popov operator can have zero modes even in the abelian case. These zero modes cannot be eliminated by restricting the path integral over a certain region in the space of gauge potentials. The conditions for the existence of these zero modes are studied for static spherically symmetric spacetimes in arbitrary dimensions. For this class of metrics, the general analytic expression of the metric components in terms of the zero modes is constructed. Such expression allows to find the asymptotic behavior of background metrics, which induce zero modes in the Coulomb gauge, an interesting example being the three dimensional Anti de-Sitter spacetime. Some of the implications for quantum field theory on curved spacetimes are discussed.

Fabrizio Canfora; Alex Giacomini; Julio Oliva

2010-04-15

358

Control of the conformations of ion Coulomb crystals in a Penning trap

Laser-cooled atomic ions form ordered structures in radiofrequency ion traps and in Penning traps. Here we demonstrate in a Penning trap the creation and manipulation of a wide variety of ion Coulomb crystals formed from small numbers of ions. The configuration can be changed from a linear string, through intermediate geometries, to a planar structure. The transition from a linear string to a zigzag geometry is observed for the first time in a Penning trap. The conformations of the crystals are set by the applied trap potential and the laser parameters, and agree with simulations. These simulations indicate that the rotation frequency of a small crystal is mainly determined by the laser parameters, independent of the number of ions and the axial confinement strength. This system has potential applications for quantum simulation, quantum information processing and tests of fundamental physics models from quantum field theory to cosmology. PMID:24096901

Mavadia, Sandeep; Goodwin, Joseph F.; Stutter, Graham; Bharadia, Shailen; Crick, Daniel R.; Segal, Daniel M.; Thompson, Richard C.

2013-01-01

359

Orbital ice: an exact Coulomb phase on the diamond lattice.

We demonstrate the existence of an orbital Coulomb phase as the exact ground state of a p-orbital exchange Hamiltonian on the diamond lattice. The Coulomb phase is an emergent state characterized by algebraic dipolar correlations and a gauge structure resulting from local constraints (ice rules) of the underlying lattice models. For most ice models on the pyrochlore lattice, these local constraints are a direct consequence of minimizing the energy of each individual tetrahedron. On the contrary, the orbital ice rules are emergent phenomena resulting from the quantum orbital dynamics. We show that the orbital ice model exhibits an emergent geometrical frustration by mapping the degenerate quantum orbital ground states to the spin-ice states obeying the 2-in-2-out constraints on the pyrochlore lattice. We also discuss possible realization of the orbital ice model in optical lattices with p-band fermionic cold atoms. PMID:22304060

Chern, Gia-Wei; Wu, Congjun

2011-12-01

360

Scaling laws for near-barrier Coulomb and nuclear breakup

NASA Astrophysics Data System (ADS)

We investigate the nuclear and the Coulomb contributions to the breakup cross sections of 6Li in collisions with targets in different mass ranges. Comparing cross sections for different targets at collision energies corresponding to the same E/VB, we obtain interesting scaling laws. First, we derive an approximate linear expression for the nuclear breakup cross section as a function of AT1/3. We then confirm the validity of this expression performing continuum-discretized coupled-channels (CDCC) calculations. Scaling laws for the Coulomb breakup cross section are also investigated. In this case, our CDCC calculations indicate that this cross section has a linear dependence on the atomic number of the target. This behavior is explained by qualitative arguments. Our findings, which are consistent with previously obtained results for higher energies, are important when planning for experiments involving exotic weakly bound nuclei.

Hussein, M. S.; Gomes, P. R. S.; Lubian, J.; Otomar, D. R.; Canto, L. F.

2013-10-01

361

Cooling of cryogenic electron bilayers via the Coulomb interaction

Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby, cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure, and analyze the power transfer. We show that across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.

John King Gamble; Mark Friesen; Robert Joynt; S. N. Coppersmith

2011-04-13

362

Coulomb corrections to the Delbrueck scattering amplitude at low energies

In this article, we study the Coulomb corrections to the Delbrueck scattering amplitude. We consider the limit when the energy of the photon is much less than the electron mass. The calculations are carried out in the coordinate representation using the exact relativistic Green function of an electron in a Coulomb field. The resulting relative corrections are of the order of a few percent for scattering on for a large charge of the nucleus. We compare the corrections with the corresponding ones calculated through the dispersion integral of the pair production cross section and also with the magnetic loop contribution to the g-factor of a bound electron. The last one is in a good agreement with our results but the corrections calculated through the dispersion relation are not.

G. G. Kirilin; I. S. Terekhov

2007-08-06

363

Coulomb drag in graphene near the Dirac point.

We study Coulomb drag in graphene near the Dirac point, focusing on the regime of interaction-dominated transport. We establish a novel, graphene-specific mechanism of Coulomb drag based on fast interlayer thermalization, inaccessible by standard perturbative approaches. Using the quantum kinetic equation framework, we derive a hydrodynamic description of transport in double-layer graphene in terms of electric and energy currents. In the clean limit the drag becomes temperature independent. In the presence of disorder the drag coefficient at the Dirac point remains nonzero due to higher-order scattering processes and interlayer disorder correlations. At low temperatures (diffusive regime) these contributions manifest themselves in the peak in the drag coefficient centered at the neutrality point with a magnitude that grows with lowering temperature. PMID:23383926

Schütt, M; Ostrovsky, P M; Titov, M; Gornyi, I V; Narozhny, B N; Mirlin, A D

2013-01-11

364

Coulomb branch Hilbert series and three dimensional Sicilian theories

NASA Astrophysics Data System (ADS)

We evaluate the Coulomb branch Hilbert series of mirrors of three dimensional Sicilian theories, which arise from compactifying the 6 d (2 , 0) theory with symmetry G on a circle times a Riemann surface with punctures. We obtain our result by gluing together the Hilbert series for building blocks T ? ( G), where ? is a certain partition related to the dual group of G, which we evaluated in a previous paper. The result is expressed in terms of a class of symmetric functions, the Hall-Littlewood polynomials. As expected from mirror symmetry, our results agree at genus zero with the superconformal index prediction for the Higgs branch Hilbert series of the Sicilian theories and extend it to higher genus. In the A 1 case at genus zero, we also evaluate the Coulomb branch Hilbert series of the Sicilian theory itself, showing that it only depends on the number of external legs.

Cremonesi, Stefano; Hanany, Amihay; Mekareeya, Noppadol; Zaffaroni, Alberto

2014-09-01

365

Is the ground state of Yang-Mills theory Coulombic?

We study trial states modelling the heavy quark-antiquark ground state in SU(2) Yang-Mills theory. A state describing the flux tube between quarks as a thin string of glue is found to be a poor description of the continuum ground state; the infinitesimal thickness of the string leads to UV artifacts which suppress the overlap with the ground state. Contrastingly, a state which surrounds the quarks with non-Abelian Coulomb fields is found to have a good overlap with the ground state for all charge separations. In fact, the overlap increases as the lattice regulator is removed. This opens up the possibility that the Coulomb state is the true ground state in the continuum limit.

Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Lutz, W. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2008-08-01

366

Coulomb blockade for tunneling through a long island

NASA Astrophysics Data System (ADS)

We consider Coulomb blockade effects for tunneling through a piece of wire with large resistance R ?1. This system can not be treated as a zero-dimensional one, as the dynamics of internal inhomogeneous degrees of freedom is crucial. At moderately high temperatures the linear conductance G of the system is suppressed due to the one-dimensional Coulomb zero bias anomaly effect. At low T, besides the standard activational factor, there is an additional T-independent (though also exponentially strong) suppression of G. It arises due to the tunneling evolution of the charge in the wire to the equivipotential distribution. In the intermediate range of T the G (T) dependence is a power law, as in the phenomenological environmental theory. The effective "environmental resistance" entering the power exponent is found explicitly. It depends on the length of the wire and on the positions of the contacts.

Feigel'man, M. V.; Ioselevich, A. S.

2014-09-01

367

Coulomb Effect in Nucleon-Deuteron Elastic Scattering

NASA Astrophysics Data System (ADS)

We have applied the quark-model nucleon-nucleon interaction fss2 to the nucleon-deuteron scattering. The screened cutoff Coulomb force in the momentum space has been incorporated to the proton-deuteron scattering by extending the matching condition, which is proposed by Vincent and Phatak for the sharply cutoff Coulomb problem. The model fss2 can reproduce the overall characteristics of the experimental data. It is found that fss2 partially incorporates the attractive feature, which accords with the good reproduction of the triton binding energy and neutron-deuteron doublet scattering length. This attractive feature is due to the off-shell effect related to the quark-model description of the short-range repulsion of the two-nucleon force.

Fukukawa, K.; Fujiwara, Y.

2013-08-01

368

Phase diagram of the Kane-Mele-Coulomb model

NASA Astrophysics Data System (ADS)

We determine the phase diagram of the Kane-Mele model with a long-range Coulomb interaction using an exact quantum Monte Carlo method. Long-range interactions are expected to play a role in honeycomb materials because the vanishing density of states in the semimetallic weak-coupling phase suppresses screening. According to our results, the Kane-Mele-Coulomb model supports the same phases as the Kane-Mele-Hubbard model. The nonlocal part of the interaction promotes short-range sublattice charge fluctuations, which compete with antiferromagnetic order driven by the onsite repulsion. Consequently, the critical interaction for the magnetic transition is significantly larger than for the purely local Hubbard repulsion. Our numerical data are consistent with SU (2) Gross-Neveu universality for the semimetal to antiferromagnet transition, and with 3D XY universality for the quantum spin Hall to antiferromagnet transition.

Hohenadler, M.; Parisen Toldin, F.; Herbut, I. F.; Assaad, F. F.

2014-08-01

369

Phase diagram of the Kane-Mele-Coulomb model

We determine the phase diagram of the Kane-Mele model with a long-range Coulomb interaction using an exact quantum Monte Carlo method. Long-range interactions are expected to play a role in honeycomb materials because the vanishing density of states in the semimetallic weak-coupling phase suppresses screening. According to our results, the Kane-Mele-Coulomb model supports the same phases as the Kane-Mele-Hubbard model. The nonlocal part of the interaction promotes short-range sublattice charge fluctuations, which compete with antiferromagnetic order driven by the onsite repulsion. Consequently, the critical interaction for the magnetic transition is significantly larger than for the purely local Hubbard repulsion. Our numerical data are consistent with $SU(2)$ Gross-Neveu universality for the semimetal to antiferromagnet transition, and with 3D XY universality for the quantum spin Hall to antiferromagnet transition.

Hohenadler, M; Herbut, I F; Assaad, F F

2014-01-01

370

Phase diagram of the Kane-Mele-Coulomb model

We determine the phase diagram of the Kane-Mele model with a long-range Coulomb interaction using an exact quantum Monte Carlo method. Long-range interactions are expected to play a role in honeycomb materials because the vanishing density of states in the semimetallic weak-coupling phase suppresses screening. According to our results, the Kane-Mele-Coulomb model supports the same phases as the Kane-Mele-Hubbard model. The nonlocal part of the interaction promotes short-range sublattice charge fluctuations, which compete with antiferromagnetic order driven by the onsite repulsion. Consequently, the critical interaction for the magnetic transition is significantly larger than for the purely local Hubbard repulsion. Our numerical data are consistent with $SU(2)$ Gross-Neveu universality for the semimetal to antiferromagnet transition, and with 3D XY universality for the quantum spin Hall to antiferromagnet transition.

M. Hohenadler; F. Parisen Toldin; I. F. Herbut; F. F. Assaad

2014-07-10

371

Coulomb effects in low-energy nuclear fragmentation

NASA Technical Reports Server (NTRS)

Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.

Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah

1993-01-01

372

Elastic scattering of Beryllium isotopes near the Coulomb barrier

In this contribution, results of experiments performed with the three Beryllium isotopes {sup 9,10,11}Be on a medium mass {sup 64}Zn target, at a center of mass energy of {approx_equal}1.4 the Coulomb barrier, will be discussed. Elastic scattering angular distributions have been measured for the {sup 9,10}Be reactions. In the {sup 11}Be case the quasielastic scattering angular distribution was obtained. In the halo nucleus case, the angular distribution exhibit a non-Fresnel-type pattern with a strong damping of the Coulomb-nuclear interference peak. Moreover, it is found that the total reaction cross-section for the halo nucleus induced collision is more than double the ones extracted in the collisions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the {sup 11}Be case could be attributed to transfer and/or break-up events.

Di Pietro, A.; Figuera, P. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Amorini, F.; Fisichella, M.; Lattuada, M.; Musumarra, A.; Pellegriti, M. G.; Randisi, G.; Rizzo, F.; Santonocito, D.; Scalia, G.; Scuderi, V.; Strano, E.; Torresi, D. [Dipartimento di Fisica ed Astronomia Universita di Catania, Catania (Italy); INFN-Laboratori Nazionali del Sud, Catania (Italy); Papa, M. [INFN-Sezione di Catania, Catania (Italy); Acosta, L.; Martel, I.; Perez-Bernal, F. [Departamento de Fisica Aplicada Universidad de Huelva, Huelva (Spain); Borge, M. J. G.; Tengblad, O. [Instituto de Estructura de la Materia CSIC, Madrid (Spain)

2011-10-28

373

Measuring Propagation Speed of Coulomb Fields

The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planets motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Li\\'enard-Weichert retarded potential leads to a formula indistinguishable from the one obtained assuming that the electric field propagates with infinite velocity. Feyman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformely moving electron beam. The results we obtain on such a finite lifetime kinematical state seem compatible with an electric field rigidly carried by the beam itself.

A. Calcaterra; R. de Sangro; G. Finocchiaro; P. Patteri; M. Piccolo; G. Pizzella

2012-11-13

374

Time-dependent electron tunnelling through a quantum dot with Coulomb interactions

NASA Astrophysics Data System (ADS)

Keldysh's nonequilibrium Green function is used to study the electron tunnelling through a quantum dot. Two kinds of intra-dot electron - electron (e - e) interaction are introduced: 0953-8984/9/23/011/img6 for the interaction at the same energy level n with different spins, and 0953-8984/9/23/011/img7 for the interaction between different levels n and m. General formulas of the time-varying current j(t) and the averaged current 0953-8984/9/23/011/img8 are derived when the external fields are applied to the system. In the time-independent linear response regime, our calculation demonstrates that the interval of the Coulomb oscillation peaks is mainly determined by 0953-8984/9/23/011/img7 which is always smaller than 0953-8984/9/23/011/img6. When the external microwave (MW) fields are applied to the system, we obtain: (1) The j(t) may become negative for a certain period of time, even if the chemical potential 0953-8984/9/23/011/img11 is larger than 0953-8984/9/23/011/img12 all the time. (2) The calculated structure of the Coulomb oscillation peaks (in asymmetric MW fields) is in good agreement with the experimental results of Kouwenhoven et al. (3) For the symmetric MW field case, our theoretical results are well consistent with the experiments of Blick et al and Drexler et al.

Sun, Qing-feng; Lin, Tsung-han

1997-06-01

375

Electron correlation in three-body Coulomb states of barium

We excited a special class of states of a three-body Coulomb system, populating double Rydberg states of the type Ngng [N=5-9, n>>N where N (n) is the principal quantum number of the inner (outer) valence electron] in Ba with both valence electrons in non-core-penetrating orbits with the same orbital angular momentum. Electron correlation effects manifest themselves by the appearance of

R. van Leeuwen; W. M. G. Ubachs; P. Camus; W. Hogervorst

1996-01-01

376

Molecular Dynamics Simulation of Shear Moduli for Coulomb Crystals

Torsional (shear) oscillations of neutron stars may have been observed in quasiperiodic oscillations of Magnetar Giant Flares. The frequencies of these modes depend on the shear modulus of neutron star crust. We calculate the shear modulus of Coulomb crystals from molecular dynamics simulations. We find that electron screening reduces the shear modulus by about 10% compared to previous Ogata et al. results. Our MD simulations can be extended to calculate the effects of impurities and or polycrystalline structures on the shear modulus.

C. J. Horowitz; J. Hughto

2008-12-15

377

Monte Carlo study of a generalized Coulomb Milne problem

Because of its relevance to the I-M coupling, we investigated the diffusion of a minor ion species through a non-uniform background major ion species. Fokker-Planck expression was used to represent the coulomb ion-ion collisions. Change of variables was implemented in order to transform the problem into a simpler form where the background medium is uniform. This transformed problem described minor

I. Barghouthi; A. Barakat

2004-01-01

378

Exact solution for two-dimensional Coulomb matrix elements

Exact analytic expression is derived for the matrix elements of the Coulomb interaction in two dimensions in the form of a closed finite sum expression. The orthonormal complete set of eigenfunctions of the harmonic oscillator is used as the basis for spanning real space. Several recurrence relations have been found in order to simplify the task of calculating the usually vast amount of elements required for any computer simulation.

Jaime Zaratiegui

2006-10-26

379

Quantum calculation of Coulomb reorientation and near-barrier fusion

We investigate the role of deformation on the fusion probability around the barrier using the Time-Dependent Hartree-Fock theory with a full Skyrme force. We obtain a distribution of fusion probabilities around the nominal barrier due to the different contributions of the various orientations of the deformed nucleus at the touching point. It is also shown that the long range Coulomb reorientation reduces the fusion probability around the barrier.

Cédric Simenel; Michael Bender; Philippe Chomaz; Thomas Duguet; Gilles De France

2006-05-08

380

Stability characterizations of fixtured rigid bodies with Coulomb friction

This paper formally introduces several stability characterizations of fixtured three-dimensional rigid bodies initially at rest and in unilateral contact with Coulomb friction. These characterizations, weak stability and strong stability, arise naturally from the dynamic model of the system, formulated as a complementarity problem. Using the tools of complementarity theory, these characterizations are studied in detail to understand their properties and to develop techniques to identify the stability classifications of general systems subjected to known external loads.

PANG,J.S.; TRINKLE,JEFFREY C.

2000-02-15

381

Coulomb field scattering in Born-Infeld electrodynamics

In the context of Born-Infeld electrodynamics, the electromagnetic fields interact with each other via their nonlinear couplings. A calculation will be performed where an incoming electromagnetic plane wave scatters off a Coulomb field in the geometrical optics approximation. In addition to finding the first-order angle of deflection, exact solutions for the trajectory will also be found. The possibility of electromagnetic bound states will be discussed.

Tennant, Daniel [Department of Physics, Austin Community College, Austin, Texas 78758 (United States)

2011-02-15

382

Effective Coulomb interaction in LaMnO 3

NASA Astrophysics Data System (ADS)

Electronic structures of perovskite oxides LaMnO 3 were studied using the density functional methods. Our calculations indicated that although the effects of Jahn-Teller distortion play a main role in getting the correct ground state, a reasonable strong electron correlation correction is necessary for obtaining the exact band structure and 3.5 eV is a good choice for the on-site Coulomb parameter U.

Geng, Tao; Han, Zengzhi; Zhuang, Songlin

2010-09-01

383

Surface vs. bulk Coulomb correlations in photoemission spectra of perovskites

Recent photoemission spectra of perovskites such as SrVO3 and SrRuO3 revealed strong modifications associated with surface contributions.^1 To study the effect of Coulomb correlations in the bulk and at the surface the quasi-particle spectra are evaluated using the dynamical mean field theory based on multi-band Quantum Monte Carlo calculations and realistic layer dependent local density of states. It is shown

Ansgar Liebsch

2003-01-01

384

The formation of Coulomb clusters in a magnetic trap

NASA Astrophysics Data System (ADS)

The possibility of confining the Coulomb clusters formed by charged diamagnetic particles in a nonuniform magnetic field in the state of levitation is confirmed theoretically and experimentally. On the basis of rather general assumptions about the symmetry properties of the magnetic field configuration, we have developed a theoretical approach to the calculation of the magnetic trap for diamagnetic particles. Equations determining the positions of a single particle and two-particle clusters in the magnetic trap, as well as the conditions of their steady state, are obtained. An experimental setup is described that is capable of creating such a trap with a magnetic field B?1 T and |?B|?10 T cm-1. The formation and confinement of clusters of charge graphite particles of size 100-300 ?m in the magnetic trap have been observed. Calculations of the trap and two-particle clusters in the trap have been performed. It is inferred that it will be possible to form stable three-dimensional dust structures such as Coulomb crystals and Coulomb liquids containing several thousands of particles under terrestrial conditions by using more intensive magnetic fields B>10 T. Less intensive magnetic fields (B?0.1 T, |?B|?0.1 T cm-1) will be required for studying analogous structures under microgravity conditions aboard space vehicles.

Savin, S. F.; D'yachkov, L. G.; Myasnikov, M. I.; Petrov, O. F.; Fortov, V. E.

2012-03-01

385

Optimal reconfigurations of two-craft Coulomb formations along manifolds

NASA Astrophysics Data System (ADS)

Coulomb formations refer to swarms of closely flying spacecraft, in which the net electric charge of each vehicle is controlled. Active charge control is central to this concept and enables a propulsion system with highly desirable characteristics, albeit with limited controllability. Numerous Coulomb formation equilibria have been derived, but to maintain and maneuver these configurations, some inertial thrust is required to supplement the nearly propellant-less charge control. In this work, invariant manifold theory is applied to two-craft Coulomb equilibria, which are admitted in a linearized two-body gravity model. The manifolds associated with these systems are analyzed for the first time, and are then utilized as part of a general procedure for formulating optimal reconfigurations. Specifically, uncontrolled flows along the manifolds are sought which provide near continuous transfers from one equilibrium to another. Control is then introduced to match continuity, while minimizing inertial thrusting. This methodology aims to exploit uncontrolled motions and charge control to realize the shape-changing ability of these formations, without large inertial control efforts. Some variations in formulating and parameterizing the optimal transfers are discussed, and analytical expressions are derived to aid in establishing control parameter limits, under certain assumptions. Numerical results are provided, as demonstrative examples of the optimization procedure, using relatively simple control approximations. Finally, Particle Swarm Optimization, a novel stochastic method, is used with considerable success to solve the numerically difficult parameter optimization problems.

Jones, Drew R.; Schaub, Hanspeter

2013-02-01

386

Coulomb excitation of the proton-dripline nucleus Na20

NASA Astrophysics Data System (ADS)

The low-energy structure of the proton dripline nucleus Na20 has been studied using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. A 1.7-MeV/nucleon Na20 beam of ~5×106 ions/s was Coulomb excited by a 0.5-mg/cm2natTi target. Scattered beam and target particles were detected by the BAMBINO segmented Si detector while ? rays were detected by two TIGRESS HPGe clover detectors set perpendicular to the beam axis. Coulomb excitation from the 2+ ground state to the first excited 3+ and 4+ states was observed, and B(?L) values were determined using the 2+?0+ de-excitation in Ti48 as a reference. The resulting B(?L)? values are B(E2;3+?2+)=55±6e2fm4 (17.0±1.9 W.u.), B(E2;4+?2+)=35.7±5.7e2fm4 (11.1±1.8 W.u.), and B(M1;4+?3+)=0.154±0.030?N2 (0.086±0.017 W.u.). These measurements provide the first experimental determination of B(?L) values for this proton dripline nucleus of astrophysical interest.

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C. J.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

2009-10-01

387

Dynamical saddle vs Coulomb saddle in antiproton impact ionization

NASA Astrophysics Data System (ADS)

The slow Coulomb breakup of a bound pair of particles by charged particle impact is often characterized by the Coulomb saddle located between the two like charges. If the breakup includes an antiproton, however, the particles experience forces on the Coulomb saddle and will tend to drift off the saddle, possibly preventing three particle breakup. There is however a dynamical saddle which eliminates these drift forces among the particles as the system breaks up, analogous to the situation in positron impact ionization. (K. A. Poelstra, J. M. Feagin and H. Klar, J. Phys. B27, 781 (1994).) In the case of antiproton impact, we thus find a dynamical saddle dominated by the proton-antiproton center of mass with the proton between the two negative charges but about six times closer to the antiproton than the electron. We will present a derivation of the resulting Wannier threshold law and consider possible probes of these fundamental saddles with the antiproton replaced by a negative ion.

Goddard, M.; Feagin, J. M.

1996-05-01

388

Coulomb blockade phenomena observed in supported metallic nanoislands

NASA Astrophysics Data System (ADS)

The electron transport properties of single crystalline metallic nanostructures in the Coulomb blockade regime have been investigated by low-temperature scanning tunneling spectroscopy. To this end, nanoscale flat-top Pb islands with well-defined geometries are grown on NaCl-covered Ag(111) substrate. The tunneling spectra acquired at 4.6 K on the Pb nanoislands reflect the presence of single electron tunneling processes across the double-barrier tunnel junction (DBTJ). By a controlled change of the tip-island tunnel distance, the spectra display the characteristic evolution from Coulomb blockade (CB) to Coulomb staircase (CS) regime. Simulations within the semi-classical orthodox theory allow us to extract quantitatively the parameters characterizing the DBTJ, i. e., the resistances, capacitances, and the residual charge Q0. Manipulation of Q0 is achieved by controlled application of voltage pulses on the Pb islands. Moreover, under specific tunneling conditions, the influence of the tip-island junction on Q0 is revealed in topographic images of the Pb islands.

Schneider, Wolf-Dieter

2013-09-01

389

NASA Astrophysics Data System (ADS)

Elastic scattering angular distributions and heavy residue production cross sections have been measured at different energies around the Coulomb barrier for the systems 6,7Li+64Zn. Optical model fits of the elastic angular distributions were performed using a renormalized double folding potential and absence of usual threshold anomaly in the optical potential was found. Excitation functions for heavy residue production have been measured using an activation technique. Comparison of the data with the results of different calculations show that complete fusion is the dominant reaction mechanism above the barrier, whereas the heavy residue yield below the barrier is mainly due to incomplete fusion and transfer.

Figuera, P.; Di Pietro, A.; Strano, E.; Fisichella, M.; Lattuada, M.; Milin, M.; Musumarra, A.; Ostashko, V.; Pellegriti, M. G.; Randisi, G.; Scuderi, V.; Torresi, D.; Zadroa, M.

2013-12-01

390

NASA Astrophysics Data System (ADS)

Fluid injection in and withdrawal from wells are basic procedures in mining activities and deep resources exploitation, such as oil and gas extraction, permeability enhancement for geothermal exploitation and waste fluid disposal. All of these activities have the potential to induce seismicity, as exemplified by the 2006 Basel earthquake (ML 3.4). Despite several decades of experience, the mechanisms of induced seismicity are not known in detail, which prevents effective risk assessment and/or mitigation. In this study, we provide an interpretation of induced seismicity based on computation of Coulomb stress changes that result from fluid injection/withdrawal at depth, mainly focused on the interpretation of induced seismicity due to stimulation of a geothermal reservoir. Seismicity is, theoretically, more likely where Coulomb stress changes are larger. For modeling purposes, we simulate the thermodynamic evolution of a system after fluid injection/withdrawal. The associated changes in pressure and temperature are subsequently considered as sources of incremental stress changes, which are then converted to Coulomb stress changes on favourably oriented faults, taking into account the background regional stress. Numerical results are applied to the water injection that was performed to create the fractured reservoir at the enhanced-geothermal-system site, Soultz-sous-Forets (France). Our approach describes well the observed seismicity, and provides an explanation for the different behaviors of a system when fluids are injected or withdrawn.

Troiano, Antonio; Di Giuseppe, Maria Giulia; Troise, Claudia; Tramelli, Anna; De Natale, Giuseppe

2013-10-01

391

NASA Astrophysics Data System (ADS)

In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasifission, and deep quasifission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reactions of 34,36S + 238U and 30Si + 238U at several incident energies around the Coulomb barrier. We find that the time scale in the quasifission as well as the deformation of fission fragments at the scission point are different between the 30Si + 238U and 36S + 238U systems, causing different mass asymmetries of the quasifission.

Aritomo, Y.; Hagino, K.; Nishio, K.; Chiba, S.

2012-04-01

392

In this paper we use the latest corrections to the Newton-Einstein secular perihelion rates of some planets of the Solar System, phenomenologically estimated with the EPM2004 ephemerides by the Russian astronomer E.V. Pitjeva, to put severe constraints on the range parameter lambda characterizing the Yukawa-like modifications of the Newtonian inverse-square law of gravitation. It turns out that the range cannot exceed about one tenth of an Astronomical Unit. We assumed neither equivalence principle violating effects nor spatial variations of $\\alpha$ and $\\lambda$. This finding may have important consequences on all the modified theories of gravity involving Yukawa-type terms with range parameters much larger than the Solar System size. However, caution is advised since we, currently have at our disposal only the periehlion extra-rates estimated by Pitjeva: if and when other groups will estimate their own corrections to the secular motion of perihelia, more robust and firm tests may be conducted.

Lorenzo Iorio

2007-08-08

393

We discuss possibility to obtain stronger constraints on non-Newtonian gravity from measuring the gradient of the Casimir force between a cylinder and a plate. Exact analytical expression for the Yukawa-type force in a cylinder-plate configuration is obtained, as well as its asymptotic expansions. The gravitational force is compared with the Casimir force acting between a cylinder and a plate. Numerical computations for the prospective constraints on non-Newtonian gravity are performed for recently proposed experiment using a microfabricated cylinder attached to a micromachined oscillator. Specifically, it is shown that this experiment is expected to obtain up to 70 times stronger constraints on the Yukawa-type force, compared with the best present day limits, over a wide interaction range from 12.5 to 630 nm.

G. L. Klimchitskaya; C. Romero

2010-11-12

394

We discuss the possibility of obtaining stronger constraints on non-Newtonian gravity from measuring the gradient of the Casimir force between a cylinder and a plate. The exact analytical expression for the Yukawa-type force in a cylinder-plate configuration is obtained, as well as its asymptotic expansions. The gravitational force is compared with the Casimir force acting between a cylinder and a plate. Numerical computations for the prospective constraints on non-Newtonian gravity are performed for a recently proposed experiment using a microfabricated cylinder attached to a micromachined oscillator. Specifically, it is shown that this experiment is expected to obtain up to 70 times stronger constraints on the Yukawa-type force, compared with the best present day limits, over a wide interaction range from 12.5 to 630 nm.

Klimchitskaya, G. L.; Romero, C. [Department of Physics, Federal University of Paraiba, C.P.5008, CEP 58059-900, Joao Pessoa, Pb (Brazil)

2010-12-01

395

Appearance of interatomic Coulombic decay in Ar, Kr, and Xe homonuclear dimers

Interatomic Coulombic decay (ICD) is observed in the rare gas homonuclear dimers Ar{sub 2}, Kr{sub 2}, and Xe{sub 2} with photoion spectroscopy techniques. Inner valence ionization of the outer ns shell of these systems is known to create a metastable state that dissociates to form a ground state ion and a neutral excited fragment. Inner valence ionization to form ns satellite states leads to similar dissociations, but the neutral fragment gets all the more excited as the internal energy of the ns satellite state increases. When enough excitation energy is transferred to reach the ionization potential, ICD occurs. ICD threshold is observed to coincide with the position of the A{sup +}A{sup +} ground state in the Franck-Condon region.

Lablanquie, P.; Aoto, T.; Hikosaka, Y.; Morioka, Y.; Penent, F.; Ito, K. [LCP-MR, Universite Pierre et Marie Curie--Paris 6 et CNRS (UMR 7614), 11 Rue P et M Curie, 75231 Paris (France); Photon Factory, IMSS, Oho 1-1, Tsukuba 305-0801 (Japan); UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305 (Japan); LCP-MR, Universite Pierre et Marie Curie--Paris 6 et CNRS (UMR 7614), 11 Rue P et M Curie, 75231 Paris (France); Photon Factory, IMSS, Oho 1-1, Tsukuba 305-0801 (Japan)

2007-10-21

396

Analysis of Coulomb breakup experiments of 8B with a dynamical eikonal approximation

Various measurements of the Coulomb breakup of 8B are analyzed within the dynamical eikonal approximation using a single description of 8B. We obtain a good agreement with experiment for different observables measured between 40 and 80 MeV per nucleon. A simple 7Be-p potential model description of 8B seems sufficient to describe all observables. In particular, the asymmetry in parallel-momentum distributions due to E1-E2 interferences is well reproduced without any scaling. The projectile-target nuclear interactions seem negligible if data are selected at forward angles. On the contrary, like in previous analyzes we observe a significant influence of higher-order effects. The accuracy of astrophysical S factors for the 7Be(p,gamma)8B reaction at stellar energies extracted from breakup measurements therefore seems difficult to evaluate.

Goldstein, G; Baye, D

2007-01-01

397

Analysis of Coulomb breakup experiments of {sup 8}B with a dynamical eikonal approximation

Various measurements of the Coulomb breakup of {sup 8}B are analyzed within the dynamical eikonal approximation using a single description of {sup 8}B. We obtain a good agreement with experiment for different observables measured between 40 and 80 MeV/nucleon. A simple {sup 7}Be-p potential model description of {sup 8}B seems sufficient to describe all observables. In particular, the asymmetry in parallel-momentum distributions due to E1-E2 interferences is well reproduced without any scaling. The projectile-target nuclear interactions seem negligible if data are selected at forward angles. On the contrary, like in previous analyses we observe a significant influence of higher-order effects. The accuracy of astrophysical S factors for the {sup 7}Be(p,{gamma}){sup 8}B reaction at stellar energies extracted from breakup measurements therefore seems difficult to evaluate.

Goldstein, G.; Capel, P.; Baye, D. [Physique Quantique, C.P. 165/82 and Physique Nucleaire Theorique et Physique Mathematique, C.P. 229, Universite Libre de Bruxelles (ULB), B 1050 Brussels (Belgium)

2007-08-15

398

Analysis of Coulomb breakup experiments of 8B with a dynamical eikonal approximation

Various measurements of the Coulomb breakup of 8B are analyzed within the dynamical eikonal approximation using a single description of 8B. We obtain a good agreement with experiment for different observables measured between 40 and 80 MeV per nucleon. A simple 7Be-p potential model description of 8B seems sufficient to describe all observables. In particular, the asymmetry in parallel-momentum distributions due to E1-E2 interferences is well reproduced without any scaling. The projectile-target nuclear interactions seem negligible if data are selected at forward angles. On the contrary, like in previous analyzes we observe a significant influence of higher-order effects. The accuracy of astrophysical S factors for the 7Be(p,gamma)8B reaction at stellar energies extracted from breakup measurements therefore seems difficult to evaluate.

G. Goldstein; P. Capel; D. Baye

2007-08-02

399

In this paper we consider general relativity and its combination with scalar quantum electrodynamics (QED) as an effective quantum field theory at energies well below the Planck scale. This enables us to compute the one-loop quantum corrections to the Newton and Coulomb potential induced by the combination of graviton and photon fluctuations. We derive the relevant Feynman rules and compute the nonanalytical contributions to the one-loop scattering matrix for charged scalars in the nonrelativistic limit. In particular, we derive the post-Newtonian corrections of order $Gm/\\text c^2 r$ from general relativity and the genuine quantum corrections of order $G\\hbar/\\text c^3 r^2$.

Sven Faller

2007-08-13

400

Four-body effects on 9Be + 208Pb scattering and fusion around the Coulomb barrier

We investigate the 9Be + 208Pb elastic scattering and fusion at energies around the Coulomb barrier. The $^9$Be nucleus is described in a \\alpha + \\alpha + n three-body model, using the hyperspherical coordinate method. The scattering with $^{208}$Pb is then studied with the Continuum Discretized Coupled Channel (CDCC) method, where the \\alpha + \\alpha + n continuum is approximated by a discrete number of pseudostates. Optical potentials for the $\\alpha+^{208}$Pb and $n+^{208}$Pb systems are taken from the literature. We present elastic-scattering and fusion cross sections at different energies, and investigate the convergence with respect to the truncation of the \\alpha + \\alpha + n continuum. A good agreement with experiment is obtained, considering that there is no parameter fitting. We show that continuum effects increase at low energies.

Descouvemont, P; Canto, L F; Hussein, M S

2014-01-01

401

Conventional density functional theory (DFT) fails for strongly correlated electron systems due to large intra-atomic self-interaction errors. The DFT+U method provides a means of overcoming these errors through the use of a parametrized potential that employs an exact treatment of quantum mechanical exchange interactions. The parameters that enter into this potential correspond to the spherically averaged intra-atomic Coulomb (U) and exchange (J) interactions. Recently, we developed an ab initio approach for evaluating these parameters on the basis of unrestricted Hartree-Fock (UHF) theory, which has the advantage of being free of self-interaction errors and does not require experimental input [Mosey and Carter, Phys. Rev. B 76, 155123 (2007)]. In this work, we build on that method to develop a more robust and convenient ab initio approach for evaluating U and J. The new technique employs a relationship between U and J and the Coulomb and exchange integrals evaluated using the entire set of UHF molecular orbitals (MOs) for the system. Employing the entire set of UHF MOs renders the method rotationally invariant and eliminates the difficulty in selecting unambiguously the MOs that correspond to localized states. These aspects overcome two significant deficiencies of our earlier method. The new technique is used to evaluate U and J for Cr(2)O(3), FeO, and Fe(2)O(3). The resulting values of U-J are close to empirical estimates of this quantity for each of these materials and are also similar to results of constrained DFT calculations. DFT+U calculations using the ab initio parameters yield results that are in good agreement with experiment. As such, this method offers a means of performing accurate and fully predictive DFT+U calculations of strongly correlated electron materials. PMID:18624466

Mosey, Nicholas J; Liao, Peilin; Carter, Emily A

2008-07-01

402

We study the role of dispersion and electrostatic interactions in the wetting behavior of ionic liquids on non-ionic solid substrates. We consider a simple model of an ionic liquid consisting of spherical ions that interact via Lennard-Jones and Coulomb potentials. Bulk and interfacial properties are computed for five fluids distinguished by the strength of the electrostatic interaction relative to the dispersion interaction. We employ Monte Carlo simulations and an interface-potential-based approach to calculate the liquid-vapor and substrate-fluid interfacial properties. Surface tensions for each fluid are evaluated over a range of temperatures that spans from a reduced temperature of approximately 0.6 to the critical point. Contact angles are calculated at select temperatures over a range of substrate-fluid interaction strengths that spans from the near-drying regime to the wetting regime. We observe that an increase in the relative strength of Coulombic interactions between ions leads to increasing deviation from Guggenheim's corresponding states theory. We show how this deviation is related to lower values of liquid-vapor excess entropies observed for strongly ionic fluids. Our results show that the qualitative nature of wetting behavior is significantly influenced by the competition between dispersion and electrostatic interactions. We discuss the influence of electrostatic interactions on the nature of wetting and drying transitions and corresponding states like behavior observed for contact angles. For all of the fluids studied, we observe a relatively narrow range of substrate-fluid interaction strengths wherein the contact angle is nearly independent of temperature. The influence of the ionic nature of the fluid on the temperature dependence of contact angle is also discussed. PMID:25381536

Rane, Kaustubh S; Errington, Jeffrey R

2014-11-01

403

Coulomb energy determination of a single Si dangling bond.

Determination of the Coulomb energy of single point defects is essential because changing their charge state critically affects the properties of materials. Based on a novel approach that allows us to simultaneously identify a point defect and to monitor the occupation probability of its electronic state, we unambiguously measure the charging energy of a single Si dangling bond with tunneling spectroscopy. Comparing the experimental result with tight-binding calculations highlights the importance of the particular surrounding of the localized state on the effective charging energy. PMID:21231404

Nguyen, T H; Mahieu, G; Berthe, M; Grandidier, B; Delerue, C; Stiévenard, D; Ebert, Ph

2010-11-26

404

Coulomb excitation of neutron-rich Cd isotopes

NASA Astrophysics Data System (ADS)

The isotopes Cd122,124,126 were studied in a "safe" Coulomb-excitation experiment at the radioactive ion-beam facility REX-ISOLDE at CERN. The reduced transition probabilities B (E2;0g .s.+?21+) and limits for the quadrupole moments of the first 2+ excited states in the three isotopes were determined. The onset of collectivity in the vicinity of the Z =50 and N =82 shell closures is discussed by comparison with shell model and beyond mean-field calculations.

Ilieva, S.; Thürauf, M.; Kröll, Th.; Krücken, R.; Behrens, T.; Bildstein, V.; Blazhev, A.; Bönig, S.; Butler, P. A.; Cederkäll, J.; Davinson, T.; Delahaye, P.; Diriken, J.; Ekström, A.; Finke, F.; Fraile, L. M.; Franchoo, S.; Fransen, Ch.; Georgiev, G.; Gernhäuser, R.; Habs, D.; Hess, H.; Hurst, A. M.; Huyse, M.; Ivanov, O.; Iwanicki, J.; Kent, P.; Kester, O.; Köster, U.; Lutter, R.; Mahgoub, M.; Martin, D.; Mayet, P.; Maierbeck, P.; Morgan, T.; Niedermeier, O.; Pantea, M.; Reiter, P.; Rodríguez, T. R.; Rolke, Th.; Scheit, H.; Scherillo, A.; Schwalm, D.; Seidlitz, M.; Sieber, T.; Simpson, G. S.; Stefanescu, I.; Thiel, S.; Thirolf, P. G.; Van de Walle, J.; Van Duppen, P.; Voulot, D.; Warr, N.; Weinzierl, W.; Weisshaar, D.; Wenander, F.; Wiens, A.; Winkler, S.

2014-01-01

405

Universal monopole scaling near transitions from the Coulomb phase.

Certain frustrated systems, including spin ice and dimer models, exhibit a Coulomb phase at low temperatures, with power-law correlations and fractionalized monopole excitations. Transitions out of this phase, at which the effective gauge theory becomes confining, provide examples of unconventional criticality. This Letter studies the behavior at nonzero monopole density near such transitions, using scaling theory to arrive at universal expressions for the crossover phenomena. For a particular transition in spin ice, quantitative predictions are made by mapping to the XY model and confirmed using Monte Carlo simulations. PMID:23006280

Powell, Stephen

2012-08-10

406

Coulombic wall slip of concentrated soft-particle suspensions

NASA Astrophysics Data System (ADS)

The coefficients of friction of concentrated soft-particle suspensions (tomato paste and a microgel suspension) were measured as a function of the slip velocity for a number of substrates. The data are interpreted using a micro-elastohydrodynamic model that is consistent with significant bulk frictional dissipation and an increase in the number of particle-wall contacts with increasing normal stress. The origin of the Coulombic slip, which has not been observed previously for pastes, is ascribed to the sensitivity of the lubricating film thickness.

Adams, Michael; Liu, Wei; Zhang, Zhibing; Fryer, Peter

2013-06-01

407

Coulombic quantum liquids in spin-1/2 pyrochlores.

We develop a nonperturbative gauge mean field theory (gMFT) method to study a general effective spin-1/2 model for magnetism in rare earth pyrochlores. gMFT is based on a novel exact slave-particle formulation, and matches both the perturbative regime near the classical spin ice limit and the semiclassical approximation far from it. We show that the full phase diagram contains two exotic phases: a quantum spin liquid and a Coulombic ferromagnet, both of which support deconfined spinon excitations and emergent quantum electrodynamics. Phenomenological properties of these phases are discussed. PMID:22400778

Savary, Lucile; Balents, Leon

2012-01-20

408

Non-Markovian qubit dynamics induced by Coulomb crystals

NASA Astrophysics Data System (ADS)

We investigate the backflow of information in a system with a second-order structural phase transition, namely, a quasi-one-dimensional Coulomb crystal. Using standard Ramsey interferometry which couples a target ion (the system) to the rest of the chain (a phononic environment), we study the non-Markovian character of the resulting open system dynamics. We study two different time scales and show that the backflow of information pinpoints both the phase transition and different dynamical features of the chain as it approaches criticality. We also establish an exact link between the backflow of information and the Ramsey fringe visibility.

Borrelli, Massimo; Haikka, Pinja; De Chiara, Gabriele; Maniscalco, Sabrina

2013-07-01

409

Ground state of two-dimensional Yukawa bosons: Applications to vortex melting

Using variational and diffusion Monte Carlo techniques, we investigate the ground state of bosons interacting in the continuum through a repulsive modified-Bessel-function potential, [epsilon][ital K][sub 0]([ital r]/[sigma]), in two dimensions. This is a simplified model for flux lines in high-[ital T][sub [ital c

Magro, W.R.; Ceperley, D.M. (National Center for Supercomputing Applications and Department of Physics, University of Illinois, Urbana, Illinois 61801 (United States))

1993-07-01

410

Aharonov-Bohm and Coulomb Scattering Near the Forward Direction

The exact wave functions that describe scattering of a charged particle by a confined magnetic field (Aharonov-Bohm effect) and by a Coulomb field are analyzed. It is well known that the usual procedure of finding asymptotic forms of these functions which admit a separation into a superposition of an incident plane wave and a circular or spherical scattered wave is problematic near the forward direction. It thus appears to be impossible to express the conservation of probability by means of an optical theorem of the usual kind. Both the total cross section and the forward scattering amplitude appear to be infinite. To address these difficulties we find a new representation for the asymptotic form of the Aharonov-Bohm wave function that is valid for all angles. Rather than try to define a cross section at forward angles, however, we work instead with the probability current and find that it is quite well behaved. The same is true for Coulomb scattering. We trace the usual difficulties to a nonuniformity of lim...

Sommerfield, C M; Sommerfield, Charles M.; Minakata, Hisakazu

2000-01-01

411

2003), Coulomb stress accumulation along the San Andreas Fault system

[1] Stress accumulation rates along the primary segments of the San Andreas Fault system are computed using a three-dimensional (3-D) elastic half-space model with realistic fault geometry. The model is developed in the Fourier domain by solving for the response of an elastic half-space due to a point vector body force and analytically integrating the force from a locking depth to infinite depth. This approach is then applied to the San Andreas Fault system using published slip rates along 18 major fault strands of the fault zone. GPS-derived horizontal velocity measurements spanning the entire 1700 200 km region are then used to solve for apparent locking depth along each primary fault segment. This simple model fits remarkably well (2.43 mm/yr RMS misfit), although some discrepancies occur in the Eastern California Shear Zone. The model also predicts vertical uplift and subsidence rates that are in agreement with independent geologic and geodetic estimates. In addition, shear and normal stresses along the major fault strands are used to compute Coulomb stress accumulation rate. As a result, we find earthquake recurrence intervals along the San Andreas Fault system to be inversely proportional to Coulomb stress accumulation rate, in agreement with typical coseismic stress drops of 1–10 MPa. This 3-D deformation model can ultimately be extended to include both time-dependent forcing and viscoelastic response.

Bridget Smith; David S

412

Spin Coulomb drag and optical excitations in low dimensional systems

NASA Astrophysics Data System (ADS)

Within the remit of new quantum technologies, an intense effort is devoted to improving our understanding of spin dynamics, with the aim of building novel spintronics devices. In this context the theory of spin Coulomb drag (SCD) was recently developed. It shows that Coulomb interactions are an intrinsic decay mechanism for spin currents. As confirmed by experiments, SCD can be substantial in semiconductors, and it is bound to become one of the most serious issues in spin polarized transport, since, due to its intrinsic nature, it cannot be avoided even in the purest material. More recently the influence of SCD on optical spin-injection and spin-resolved optical experiments has been considered. Here we report on SCD effects on intersubband optical spin excitations in III-V quantum wells, where SCD may contribute substantially to the linewidth of spin plasmons. By going beyond the usual local density functional approximation and properly including the effects due to the inhomogeneity of the system in the growth direction, we show that the quantization of states in the growth direction may strongly reduce the intrinsic plasmon linewidth.

D'Amico, Irene; Ullrich, Carsten

2012-02-01

413

Coulomb effects on pions produced in heavy-ion reactions

Double differential cross sections for the production of ..pi../sup +/ and ..pi../sup -/ near the velocity of the incident beam for pion lab angles less than 40 degrees are presented. The experimental apparatus and the techniques are discussed. Beams of /sup 20/Ne with E/A from 80 to 655 MeV and /sup 40/Ar with E/A = 535 MeV incident on Be, C, NaF, KC1, Cu, and U targets were used. A sharp peak in the ..pi../sup -/ spectrum and a depression in the ..pi../sup +/ spectrum were observed at zero degrees near the incident beam velocity. The effect is explained in terms of Coulomb interactions between the pions and fragments of the incident beam. Least squares fits to the data using the Coulomb correction formulas of Gyulassy and Kauffman and an effective projectile fragment charge are made. The relationship between these data and previously measured pion production and projectile fragmentation data is discussed. The data are also compared to some theoretical models. A simple expression is given for the differential cross section as a function of the projectile mass, target mass, and beam energy.

Sullivan, J.P.

1981-11-01

414

Coulomb Stress Accumulation along the San Andreas Fault System

NASA Technical Reports Server (NTRS)

Stress accumulation rates along the primary segments of the San Andreas Fault system are computed using a three-dimensional (3-D) elastic half-space model with realistic fault geometry. The model is developed in the Fourier domain by solving for the response of an elastic half-space due to a point vector body force and analytically integrating the force from a locking depth to infinite depth. This approach is then applied to the San Andreas Fault system using published slip rates along 18 major fault strands of the fault zone. GPS-derived horizontal velocity measurements spanning the entire 1700 x 200 km region are then used to solve for apparent locking depth along each primary fault segment. This simple model fits remarkably well (2.43 mm/yr RMS misfit), although some discrepancies occur in the Eastern California Shear Zone. The model also predicts vertical uplift and subsidence rates that are in agreement with independent geologic and geodetic estimates. In addition, shear and normal stresses along the major fault strands are used to compute Coulomb stress accumulation rate. As a result, we find earthquake recurrence intervals along the San Andreas Fault system to be inversely proportional to Coulomb stress accumulation rate, in agreement with typical coseismic stress drops of 1 - 10 MPa. This 3-D deformation model can ultimately be extended to include both time-dependent forcing and viscoelastic response.

Smith, Bridget; Sandwell, David

2003-01-01

415

Revision of the Coulomb logarithm in the ideal plasma

The standard picture of the Coulomb logarithm in the ideal plasma is controversial, the arguments for the lower cut off need revision. The two cases of far subthermal and of far superthermal electron drift motions are accessible to a rigorous analytical treatment. We show that the lower cut off $b_{\\min}$ is a function of symmetry and shape of the shielding cloud, it is not universal. In the subthermal case shielding is spherical and $b_{\\min}$ is to be identified with the de Broglie wavelength; at superthermal drift the shielding cloud exhibits cylindrical (axial) symmetry and $b_{\\min}$ is the classical parameter of perpendicular deflection. In both situations the cut offs are determined by the electron-ion encounters at large collision parameters. This is in net contrast to the governing standard meaning that attributes $b_{\\min}$ to the Coulomb singularity at vanishing collision parameters $b$ and, consequently, assigns it universal validity. The origin of the contradictions in the traditional picture is analyzed.

P. Mulser; G. Alber; M. Murakami

2013-12-13

416

Local Coulomb versus Global Failure Criterion for Granular Packings

Contacts at the Coulomb threshold are unstable to tangential perturbations and thus contribute to failure at the microscopic level. How is such a local property related to global failure, beyond the effective picture given by a Mohr-Coulomb type failure criterion? Here, we use a simulated bed of frictional disks slowly tilted under the action of gravity to investigate the link between the avalanche process and a global generalized isostaticity criterion. The avalanche starts when the packing as a whole is still stable according to this criterion, underlining the role of large heterogeneities in the destabilizing process: the clusters of particles with fully mobilized contacts concentrate local failure. We demonstrate that these clusters, at odds with the pile as a whole, are also globally marginal with respect to generalized isostaticity. More precisely, we observe how the condition of their stability from a local mechanical proprety progressively builds up to the generalized isostaticity criterion as they grow in size and eventually span the whole system when approaching the avalanche.

Silke Henkes; Carolina Brito; Olivier Dauchot; Wim Van Saarloos

2010-01-13

417

Coulomb excitation of a {sup 78}Rb radioactive beam.

In order to test the feasibility of Coulomb excitation of radioactive projectiles with low beam energies and intensities, they have produced a secondary radioactive beam of {sup 78}Rb and Coulomb re-excited it. The beam was produced in the fusion evaporation reaction {sup 24}Mg({sup 58}Ni,3pn){sup 78}Rb at a beam energy of 260 MeV, using the Argonne National Laboratory ATLAS accelerator. The residues of interest were separated from other reaction products and non-interacting beam using the Fragment Mass Analyzer (FMA). The beam leaving the FMA was {sup 78}Kr and {sup 78}Rb{sup gs,m1,m2}, which was refocused onto a {sup 58}Ni secondary target. They have extracted a spectrum of {gamma}-rays associated with re-excitation of A = 78 isobars. The re-excitation of stable {sup 78}Kr was observed, which serves as a reference. Gamma-rays associated with excitation of {sup 78}Rb{sup gs,m1,m2} were also seen. The measured yields indicate that all the {sup 78}Rb states are highly deformed.

Schwartz, J.

1998-11-18

418

First-principles calculations of shear moduli for Monte Carlo-simulated Coulomb solids

NASA Technical Reports Server (NTRS)

The paper presents a first-principles study of the shear modulus tensor for perfect and imperfect Coulomb solids. Allowance is made for the effects of thermal fluctuations for temperatures up to the melting conditions. The present theory treats the cases of the long-range Coulomb interaction, where volume fluctuations should be avoided in the Ewald sums.

Ogata, Shuji; Ichimaru, Setsuo

1990-01-01

419

Lifetime of ring current particles due to Coulomb collisions in the plasmasphere

Ring current ions and electrons in the trapped belt are scattered and slowed down to Coulomb interactions with the thermal plasma in the plasmasphere and are eventually removed from trapped orbits. An expression for bounce-averged Coulomb lifetimes is derived using methods developed by Wentworth et al. (1959) but with the improvements of considering a more realistic representation of the thermal

M.-C. Fok; J. U. Kozyra; A.F. Nagy; T. E. Cravens

1991-01-01

420

Detailed electron transport analysis is performed for an ensemble of conical indium phosphide nanowires bridging two hydrogenated n(+)-silicon electrodes. The current-voltage (I-V) characteristics exhibit a Coulomb staircase in the dark with a period of ? 1 V at room temperature. The staircase is found to disappear under light illumination. This observation can be explained by assuming the presence of a tiny Coulomb island, and its existence is possible due to the large surface depletion region created within contributing nanowires. Electrons tunnel in and out of the Coulomb island, resulting in the Coulomb staircase I-V. Applying light illumination raises the electron quasi-Fermi level and the tunneling barriers are buried, causing the Coulomb staircase to disappear. PMID:21178228

Yamada, Toshishige; Yamada, Hidenori; Lohn, Andrew J; Kobayashi, Nobuhiko P

2011-02-01

421

Conductivity of the two-dimensional Coulomb glass

NASA Astrophysics Data System (ADS)

We studied by computer simulation the effects of Coulomb interactions on the properties of strongly localized Anderson insulators. We took full account of many-body effects by considering the many-electron configurations of the system rather than single-particle states. We developed an algorithm to obtain the configurations and energies of the low-lying system states, and from there the conductivity. At low-temperatures T, we found that the conductivity was proportional to exp(-T0/T)1/2. Many-electron transitions were seen to be important at very low temperatures. In this regime, T0~0.61, which is much smaller than predicted by one-electron theory. Experimental results which use the predicted T0 to obtain localization radii must therefore be reinterpreted.

Pérez-Garrido, A.; Ortuño, M.; Cuevas, E.; Ruiz, J.; Pollak, M.

1997-04-01

422

A New Coulomb Collision Model for PIC Codes

NASA Astrophysics Data System (ADS)

We develop a Coulomb collision algorithm for PIC codes based on a Langevin particle pusher that incorporates velocity sensitive collision rates. According to the algorithm, every time step of the simulation each particle collides with all other particles in a cell where the latter are modeled as one or more drifting Maxwellians. Thus, the collisional particle advance is order N where N is the number of particles in the cell. Particle-Maxwellian collisions reproduce the usual Spitzer velocity diffusion rates. Each particle-Maxwellian collision conserves momentum exactly and energy statistically. Energy conservation can be made exact with a linear velocity shift. Furthermore, the time step can be either very large or very small compared to equilibration time scales. We apply a zero-dimensional version of the algorithm to standard equilibration test problems and compare the results to other (order N^2 and particle pairing) algorithms exercised on the same problems.

Lemons, Don; Albright, B. J.; Winske, Dan

2006-10-01

423

Nonlinear screening in large two-dimensional Coulomb clusters

NASA Astrophysics Data System (ADS)

The distortion due to a fixed point impurity with variable charge placed in the center of a classical harmonically confined two-dimensional (2D) large Coulomb cluster is studied. We find that the net topological charge (N--N+) of the system is always equal to six independent of the position and charge of the impurity. In comparison with a 2D cluster without impurity charge, only the breathing mode remains unchanged. The screening length is found to be a highly nonlinear function of the impurity charge. For values of the impurity charge smaller than the charge of the other particles, the system has almost the same screening strength. When the impurity charge is larger, the screening length is strongly enhanced. This result can be explained by the competition between the different forces active in the system.

Kong, Minghui; Vagov, A.; Partoens, B.; Peeters, F. M.; Ferreira, W. P.; Farias, G. A.

2004-11-01

424

The Functional Callan-Symanzik Equation for the Coulomb Gas

NASA Astrophysics Data System (ADS)

A non-perturbative scheme, based on the functional generalization of the Callan-Symanzik equation is developed to treat the Coulomb interaction in an electron gas. The one-particle irreducible vertex functions are shown to satisfy an evolution equation whose initial condition is given by means of the classical action and the final point corresponds to the physical system. This equation is truncated by expanding it in momenta and excitation energies, leaving the electric charge as an arbitrary, not necessarily small parameter. Exact coupled partial differential equations up to first order in the frequencies and excitation energies are derived. The numerical integration of these equations is left to a later stage. Nevertheless, in order to demonstrate the relation with the perturbation expansion the one-loop Lindhard function and screening are reproduced in the independent mode approximation of the evolution equation.

Correia, Sebastiao; Polonyi, Janos; Richert, Jean

2002-03-01

425

Investigation of uncertainty components in Coulomb blockade thermometry

Coulomb blockade thermometry (CBT) has proven to be a feasible method for primary thermometry in every day laboratory use at cryogenic temperatures from ca. 10 mK to a few tens of kelvins. The operation of CBT is based on single electron charging effects in normal metal tunnel junctions. In this paper, we discuss the typical error sources and uncertainty components that limit the present absolute accuracy of the CBT measurements to the level of about 1 % in the optimum temperature range. Identifying the influence of different uncertainty sources is a good starting point for improving the measurement accuracy to the level that would allow the CBT to be more widely used in high-precision low temperature metrological applications and for realizing thermodynamic temperature in accordance to the upcoming new definition of kelvin.

Hahtela, O. M.; Heinonen, M.; Manninen, A. [MIKES Centre for Metrology and Accreditation, Tekniikantie 1, 02150 Espoo (Finland)] [MIKES Centre for Metrology and Accreditation, Tekniikantie 1, 02150 Espoo (Finland); Meschke, M.; Savin, A.; Pekola, J. P. [Low Temperature Laboratory, Aalto University, Tietotie 3, 02150 Espoo (Finland)] [Low Temperature Laboratory, Aalto University, Tietotie 3, 02150 Espoo (Finland); Gunnarsson, D.; Prunnila, M. [VTT Technical Research Centre of Finland, Tietotie 3, 02150 Espoo (Finland)] [VTT Technical Research Centre of Finland, Tietotie 3, 02150 Espoo (Finland); Penttilä, J. S.; Roschier, L. [Aivon Oy, Tietotie 3, 02150 Espoo (Finland)] [Aivon Oy, Tietotie 3, 02150 Espoo (Finland)

2013-09-11

426

Exploring Interatomic Coulombic Decay by Free Electron Lasers

To exploit the high intensity of laser radiation, we propose to select frequencies at which single-photon absorption is of too low energy and two or more photons are needed to produce states of an atom that can undergo interatomic Coulombic decay (ICD) with its neighbors. For Ne{sub 2} it is explicitly demonstrated that the proposed multiphoton absorption scheme is much more efficient than schemes used until now, which rely on single-photon absorption. Extensive calculations on Ne{sub 2} show how the low-energy ICD electrons and Ne{sup +} pairs are produced for different laser intensities and pulse durations. At higher intensities the production of Ne{sup +} pairs by successive ionization of the two atoms becomes competitive and the respective emitted electrons interfere with the ICD electrons. It is also shown that a measurement after a time delay can be used to determine the contribution of ICD even at high laser intensity.

Demekhin, Philipp V.; Stoychev, Spas D.; Kuleff, Alexander I.; Cederbaum, Lorenz S. [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

2011-12-30

427

Intermediate-energy Coulomb excitation of {sup 52}Fe

The nucleus {sup 52}Fe with (N=Z=26) has been investigated using intermediate-energy Coulomb excitation in inverse kinematics. A reduced transition probability of B(E2;0{sub 1}{sup +}{yields}2{sub 1}{sup +})=817(102) e{sup 2} fm{sup 4} to the first excited 2{sup +} state at 849.0(5) keV was deduced. The increase in excitation strength B(E2{up_arrow}) with respect to the even-mass neighbor {sup 54}Fe (B(E2{up_arrow})=620(50) e{sup 2} fm{sup 4}) agrees with shell-model expectations as the magic number N=28 is approached. This measurement completes the systematics of reduced transition strengths to the first excited 2{sup +} state for the even-even N=Z nuclei up to mass A=56.

Yurkewicz, K.L.; Brown, B.A.; Campbell, C.M.; Church, J.A.; Dinca, D.-C.; Glasmacher, T.; Olliver, H.; Terry, J.R. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States); Bazin, D.; Gade, A.; Mueller, W.F. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Honma, M. [Center for Mathematical Sciences, University of Aizu, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Mizusaki, T. [Institute of Natural Sciences, Senshu University, Higashimita, Tama, Kawasaki, Kanagawa 214-8580 (Japan); Otsuka, T. [Department of Physics and Center for Nuclear Study, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); RIKEN, Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Riley, L.A. [Department of Physics and Astronomy, Ursinus College, Collegeville, Pennsylvania 19426 (United States)

2004-09-01

428

Relativistic Coulomb excitation within Time Dependent Superfluid Local Density Approximation

Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus $^{238}$U. The approach is based on Superfluid Local Density Approximation (SLDA) formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We have computed the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, the dipole pygmy resonance and giant quadrupole modes were excited during the process. The one body dissipation of collective dipole modes is shown to lead a damping width $\\Gamma_\\downarrow \\approx 0.4$ MeV and the number of pre-equilibrium neutrons emitted has been quantified.

I. Stetcu; C. Bertulani; A. Bulgac; P. Magierski; K. J. Roche

2014-03-11

429

Coulomb problem in non-commutative quantum mechanics

The aim of this paper is to find out how it would be possible for space non-commutativity (NC) to alter the quantum mechanics (QM) solution of the Coulomb problem. The NC parameter {lambda} is to be regarded as a measure of the non-commutativity - setting {lambda}= 0 which means a return to the standard quantum mechanics. As the very first step a rotationally invariant NC space R{sub {lambda}}{sup 3}, an analog of the Coulomb problem configuration space (R{sup 3} with the origin excluded) is introduced. R{sub {lambda}}{sup 3} is generated by NC coordinates realized as operators acting in an auxiliary (Fock) space F. The properly weighted Hilbert-Schmidt operators in F form H{sub {lambda}}, a NC analog of the Hilbert space of the wave functions. We will refer to them as 'wave functions' also in the NC case. The definition of a NC analog of the hamiltonian as a hermitian operator in H{sub {lambda}} is one of the key parts of this paper. The resulting problem is exactly solvable. The full solution is provided, including formulas for the bound states for E < 0 and low-energy scattering for E > 0 (both containing NC corrections analytic in {lambda}) and also formulas for high-energy scattering and unexpected bound states at ultra-high energy (both containing NC corrections singular in {lambda}). All the NC contributions to the known QM solutions either vanish or disappear in the limit {lambda}{yields} 0.

Galikova, Veronika; Presnajder, Peter [Faculty of Mathematics, Physics and Informatics, Comenius University of Bratislava, Mlynska dolina F2, Bratislava (Slovakia)] [Faculty of Mathematics, Physics and Informatics, Comenius University of Bratislava, Mlynska dolina F2, Bratislava (Slovakia)

2013-05-15

430

Structure and phase behavior of two-Yukawa fluids with competing interactions in planar slit pores.

A density functional perturbation theory, which is based both on the modified fundamental-measure theory and on the first-order mean-spherical approximation for long-range attractive and repulsive interactions, has been developed for studying the structure and phase behaviors of a competing system restricted to slit pores. The hysteresis loop for the adsorption and desorption curves indicates that the system exhibits vapor-cluster and cluster-liquid transitions which depend on the pair potential parameters and the slit width (H). The periodic spacing (D) of the cluster is commensurate with the periodicity of modulation in the particle density distribution and more closely related to the vapor-cluster and cluster-liquid phase transitions of the system. For the cluster phase, we find the transition from a single liquidlike slab to a multi-liquidlike slab with increasing the slit width. The multi-liquidlike slab is formed depending on the periodicity of modulation by finite-size artifacts. The cluster-related phase transitions, such as the vapor-cluster or cluster-liquid transitions occur for H>D, while for H

Kim, Eun-Young; Kim, Soon-Chul; Suh, Soong-Hyuck

2012-05-01

431

Following recent work in search for a universal function (Van Hooydonk, Eur. J. Inorg. Chem., (1999), 1617), we test four symmetric +/- a(n)Rn potentials for reproducing molecular potential energy curves (PECs). Classical gauge symmetry for 1/R-potentials results in generic left right asymmetric PECs. A pair of symmetric perturbed Coulomb potentials is quantitatively in accordance with observed PECs. For a bond, a four-particle system, charge inversion (a parity effect, atom chirality) is the key to explain this shape generically. A parity adapted Hamiltonian reduces from ten to two terms and to a soluble Bohr-like formula, a Kratzer (1 - Re/R)2 potential. The result is similar to the combined action of spin and wave function symmetry upon the Hamiltonian in Heitler-London theory. Analytical perturbed Coulomb functions varying with (1 - Re/R) scale attractive and repulsive branches of PECs for 13 bonds H2, HF, LiH, KH, AuH, Li2, LiF, KLi, NaCs, Rb2, RbCs, Cs2 and I2 in a single straight line. The 400 turning points for 13 bonds are reproduced with a deviation of 0.007 A at both branches. For 230 points at the repulsive side, the deviation is 0.003 A. The perturbed electrostatic Coulomb law is a universal molecular function. Ab initio zero molecular parameter functions give PECs of acceptable quality, just using atomic ionisation energies. The function can be used as a model potential for inverting levels and gives a first principle's comparison of short- and long-range interactions, important for the study of cold atoms. Wave-packet dynamics, femto-chemistry applied to the crossing of covalent and ionic curves, can provide evidence for this theory. We anticipate this scale/shape invariant scheme applies to smaller scales in nuclear and high-energy particle physics. For larger gravitational scales (Newton 1/R potentials), problems with super-unification are discussed. Reactions between hydrogen and antihydrogen, feasible in the near future, will probably produce normal H2. PMID:11075672

Van Hooydonk, G

2000-11-01

432

Exploration of Coulomb explosion dynamics through excited vibrational states of molecules Zhongyuan Coulomb explosion CE mechanisms and dynamics through excited vibrational states of H2 + . A kinetic , disso- ciation via chemical bond softening BSD 12 and bond hardening 13,14 , Coulomb explosion CE

Chu, Shih-I

433

The monopole constraint effective potential in U(1) lattice gauge theory

NASA Astrophysics Data System (ADS)

The monopole constraint effective potentials is calculated by numerical simulations both in the confined and in the Coulomb phase of U(1) lattice gauge theory. In the confined phase magnetic monopoles condense. This is indicated by the spontaneous breakdown of a Z2 monopole field reflection symmetry. The effective potential then has two degenerate minima. In the Coulomb phase magnetic monopoles exist as stable particles. The reflection symmetry is unbroken and the effective potential has a single unique minimum.

Polikarpov, M. I.; Polley, L.; Wiese, U.-J.

1991-01-01

434

Spectral properties of quantum dots influenced by a confining potential model

NASA Astrophysics Data System (ADS)

We obtain the exact energy spectra and corresponding wave functions of the spherical quantum dots for any (n,l) state in the presence of a combination of pseudo-harmonic, Coulomb and linear confining potential terms within the exact analytical iteration method (EAIM). The interaction potential model under consideration is labeled as the Cornell modified-plus-harmonic (CMpH) type which is a correction form to the harmonic, Coulomb and linear confining potential terms.

Ikhdair, Sameer M.; Hamzavi, Majid

2012-12-01

435

NASA Astrophysics Data System (ADS)

November 2011, a M5.0 earthquake occurred less than a day before a M5.7 earthquake near Prague, Oklahoma, which may have promoted failure of the mainshock and thousands of aftershocks along the Wilzetta fault, including a M5.0 aftershock. The M5.0 foreshock occurred in close proximity to active fluid injection wells; fluid injection can cause a buildup of pore fluid pressure, decrease the fault strength, and may induce earthquakes. Keranen et al. links the M5.0 foreshock with fluid injection, but the relationship between the foreshock and successive events has not been investigated. Here we examine the role of coseismic Coulomb stress transfer on earthquakes that follow the M5.0 foreshock, including the M5.7 mainshock. We resolve the static Coulomb stress change onto the focal mechanism nodal plane that is most consistent with the rupture geometry of the three M ? 5.0 earthquakes, as well as specified receiver fault planes that reflect the regional stress orientation. We find that Coulomb stress is increased, e.g., fault failure is promoted, on the nodal planes of ~60% of the events that have focal mechanism solutions, and more specifically, that the M5.0 foreshock promoted failure on the rupture plane of the M5.7 mainshock. We test our results over a range of effective coefficient of friction values. Hence, we argue that the M5.0 foreshock, induced by fluid injection, potentially triggered a cascading failure of earthquakes along the complex Wilzetta fault system.

Sumy, Danielle F.; Cochran, Elizabeth S.; Keranen, Katie M.; Wei, Maya; Abers, Geoffrey A.

2014-03-01

436

Topological defects and nonhomogeneous melting of large two-dimensional Coulomb clusters

NASA Astrophysics Data System (ADS)

The configurational and melting properties of large two-dimensional (2D) clusters of charged classical particles interacting with each other via the Coulomb potential are investigated through the Monte Carlo simulation technique. The particles are confined by a harmonic potential. For a large number of particles in the cluster (N>150), the configuration is determined by two competing effects, namely, the fact that in the center a hexagonal lattice is formed, which is the groundstate for an infinite 2D system, and the confinement that imposes its circular symmetry on the outer edge. As a result, a hexagonal Wigner lattice is formed in the central area while at the border of the cluster the particles are arranged in rings. In the transition region defects appear as dislocations and disclinations at the six corners of the hexagonal-shaped inner domain. Many different arrangements and types of defects are possible as metastable configurations with a slightly higher energy. The particle motion is found to be strongly related to the topological structure. Our results clearly show that the melting of the clusters starts near the geometry induced defects, and that three different melting temperatures can be defined corresponding to the melting of different regions in the cluster.

Kong, Minghui; Partoens, B.; Peeters, F. M.

2003-02-01

437

Toward quantitative description of protein aggregation, we develop a computationally efficient method to evaluate the potential of mean force between two folded protein molecules that allows for complete sampling of their mutual orientation. Our model is valid at moderate ionic strengths and accounts for the actual charge distribution on the surface of the molecules, the dielectric discontinuity at the protein-solvent interface, and the possibility of protonation or deprotonation of surface residues induced by the electric field due to the other protein molecule. We apply the model to the protein lysozyme, whose solutions exhibit both mesoscopic clusters of protein-rich liquid and liquid-liquid separation; the former requires that protein form complexes with typical lifetimes of approximately milliseconds. We find the electrostatic repulsion is typically lower than the prediction of the Derjaguin-Landau-Verwey-Overbeek theory. The Coulomb interaction in the lowest-energy docking configuration is nonrepulsive, despite the high positive charge on the molecules. Typical docking configurations barely involve protonation or deprotonation of surface residues. The obtained potential of mean force between folded lysozyme molecules is consistent with the location of the liquid-liquid coexistence, but produces dimers that are too short-lived for clusters to exist, suggesting lysozyme undergoes conformational changes during cluster formation. PMID:22768950

Chan, Ho Yin; Lankevich, Vladimir; Vekilov, Peter G.; Lubchenko, Vassiliy

2012-01-01

438

NASA Astrophysics Data System (ADS)

We discuss the arising of bound states solutions to the Schrödinger equation due to the presence of a Coulomb-type potential induced by the interaction between a moving particle possessing an electric quadrupole moment and an electric field. Besides, we study the influence of the Coulomb-type potential on the harmonic oscillator by showing a quantum effect characterized by the dependence of the angular frequency on the quantum numbers of the system. Finally, we consider the quantum particle subject to harmonic and linear confining potentials and investigate the influence of the analogue of the Coulomb potential.

Bakke, K.

2014-08-01

439

Infrared analysis of propagators and vertices of Yang-Mills theory in Landau and Coulomb gauge

The infrared behavior of gluon and ghost propagators, ghost-gluon vertex, and three-gluon vertex is investigated for both the covariant Landau and the noncovariant Coulomb gauge. Assuming infrared ghost dominance, we find a unique infrared exponent in the d=4 Landau gauge, while in the d=3+1 Coulomb gauge we find two different infrared exponents. We also show that a finite dressing of the ghost-gluon vertex has no influence on the infrared exponents. Finally, we determine the infrared behavior of the three-gluon vertex analytically and calculate it numerically at the symmetric point in the Coulomb gauge.

Schleifenbaum, W.; Leder, M.; Reinhardt, H. [Institute of Theoretical Physics, University of Tuebingen, D-72076 Tuebingen (Germany)

2006-06-15

440

Measurement of E2 Transitions in the Coulomb Dissociation of 8B

In an effort to understand the implications of Coulomb dissociation experiments for the determination of the 7Be(p,gamma)8B reaction rate, longitudinal momentum distributions of 7Be fragments produced in the Coulomb dissociation of 44 and 81 MeV/nucleon 8B beams on a Pb target were measured. These distributions are characterized by asymmetries interpreted as the result of interference between E1 and E2 transition amplitudes in the Coulomb breakup. At the lower beam energy, both the asymmetries and the measured cross sections are well reproduced by perturbation theory calculations, allowing a determination of the E2 strength.

B. Davids; D. W. Anthony; Sam M. Austin; D. Bazin; B. Blank; J. A. Caggiano; M. Chartier; H. Esbensen; P. Hui; C. F. Powell; H. Scheit; B. M. Sherrill; M. Steiner; P. Thirolf

1998-03-26

441

Effect of internal energy on the repulsive Coulomb barrier of polyanions.

The nature of the repulsive Coulomb barrier in isolated molecular polyanions is studied by means of the photodetachment dynamics of the S(1) excited state of the fluorescein dianion which is bound solely by the repulsive Coulomb barrier. Photoelectron spectra reveal a feature at a constant electron kinetic energy, regardless of the excitation energy. This is explained by using an adiabatic tunneling picture for electron loss through successive repulsive Coulomb barriers correlating to vibrationally excited states. This physical picture is supported by time-resolved photoelectron spectra, showing that the tunneling lifetime is also invariant with excitation energy. PMID:22463527

Horke, Daniel A; Chatterley, Adam S; Verlet, Jan R R

2012-02-24

442

Monte Carlo study of a generalized Coulomb Milne problem

NASA Astrophysics Data System (ADS)

Because of its relevance to the I-M coupling, we investigated the diffusion of a minor ion species through a non-uniform background major ion species. Fokker-Planck expression was used to represent the coulomb ion-ion collisions. Change of variables was implemented in order to transform the problem into a simpler form where the background medium is uniform. This transformed problem described minor ions diffusing through a background of ions with constant density in the semi-infinite region tilde {z}>0 and zero density in the regiontilde {z}<0. This problem was termed the generalized Coulomb Milne problem and was addressed by a Monte Carlo simulation. Three different minor-to-background mass ratios (? ) were considered, namely ? =16, 1, and 1/16, which were relevant to H+ and O+ ions, the two most dominant ions in the terrestrial ionosphere. The minor ion velocity distribution (fs) and the velocity moments (density ( ns); drift velocity (tilde {u}_s ), parallel (tilde {T}s| | ) and perpendicular (tilde {T}sbot ) temperatures; and parallel (tilde {q}_s| | ) and perpendicular (tilde {q}_s^bot ) heat fluxes) were computed. The following were the main conclusions of the study. (1) For the cases of (? =16, 1), the distribution was close to Maxwellian at low altitudes due to collisions, gradually formed a weak upward tail in the transition region, and eventually assumed a half-Maxwellian shape at the collisionless region. This was reflected in the enhancement of TRIAL RESTRICTION for these two cases. (2) The parallel temperature was reduced (TRIAL RESTRICTION quad < 1) due to the missing down-going ions effect. (3) Deep into the collision-dominated region, ns was found to be linearly dependent on the normalized distance TRIAL RESTRICTION with a gradient (m = d n/dTRIAL RESTRICTION). As ? decreased from 16 to 1 to 1/16, m decreased from 2.0 to 1.7 to 0.75, respectively. (4) The case of (? =1/16) exhibited some qualitative differences in contrast to the other two cases. For example, a double-humped fs formed and a corresponding rapid decrease in TRIAL RESTRICTION and TRIAL RESTRICTION occurred near the transition region.

Barghouthi, I.; Barakat, A.

443

The elastic scattering of light halo nuclei in the field of heavy targets has been studied for collision energies below the Coulomb barrier. Based on the assumption that the neutron halo follows the projectile adiabatically along its classical trajectory, a dynamic polarization potential is derived which describes both the (electrical) polarization as well as the breakup of the projectile in the field of the target. Detailed computations have been carried out for the elastic scattering of {sup 6}He+{sup 209}Bi at energies between 14.7 MeV and 19.1 MeV near to the Coulomb barrier. It is demonstrated that the polarization of the halo nucleus leads to a clear decrease of the (elastic) scattering cross section in excellent agreement with a recent measurement by Aguilera et al. [Phys. Rev. Lett. 84, 5058 (2000)].

Borowska, L. [Institut fuer Physik, Universitaet Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany); Institute for Nuclear Research, National Academy of Sciences of Ukraine, Nauky Prospekt 47, 03680 Kyiv (Ukraine); Terenetsky, K.; Verbitsky, V. [Institute for Nuclear Research, National Academy of Sciences of Ukraine, Nauky Prospekt 47, 03680 Kyiv (Ukraine); Fritzsche, S. [Institut fuer Physik, Universitaet Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel (Germany)

2007-09-15

444

Low-energy cross section of the 7Be(p,g)8B solar fusion reaction from Coulomb dissociation of 8B

Final results from an exclusive measurement of the Coulomb breakup of 8B into 7Be+p at 254 A MeV are reported. Energy-differential Coulomb-breakup cross sections are analyzed using a potential model of 8B and first-order perturbation theory. The deduced astrophysical S_17 factors are in good agreement with the most recent direct 7Be(p,gamma)8B measurements and follow closely the energy dependence predicted by the cluster-model description of 8B by Descouvemont. We extract a zero-energy S_17 factor of 20.6 +- 0.8 (stat) +- 1.2 (syst) eV b.

F. Schuemann; S. Typel; F. Hammache; F. Uhlig; K. Suemmerer; I. Boettcher; D. Cortina; A. Foerster; M. Gai; H. Geissel; U. Greife; E. Grosse; N. Iwasa; P. Koczon; B. Kohlmeyer; R. Kulessa; H. Kumagai; N. Kurz; M. Menzel; T. Motobayashi; H. Oeschler; A. Ozawa; M. Ploskon; W. Prokopowicz; E. Schwab; P. Senger; F. Strieder; C. Sturm; Zhi-Yu Sun; G. Surowka; A. Wagner; W. Walus

2005-08-11

445

NASA Astrophysics Data System (ADS)

The radial sensitivity of the elastic scattering of the weakly-bound 6Li and halo 6He nuclei on medium-mass 64Zn target and heavy target 208Pb is examined around the Coulomb barrier energies. We present that very good agreement between theoretical and experimental results have been obtained with small ?2/N values. The fusion cross-section and volume integrals of the potentials have been deduced from the theoretical calculations for all studied systems at relevant energies. We have also analyzed the elastic scattering of the 6He+208Pb system at Elab = 14, 16, 18, 22, 27 MeV in order to investigate whether there is a dispersion relation between the real and imaginary parts of the optical potential.

Sert, Y.; Caner, T.; Bayrak, O.; Boztosun, I.

2012-07-01

446

NASA Astrophysics Data System (ADS)

We study massless Dirac fermions in a supercritical Coulomb potential with the emphasis on that its low-energy physics is universal and parametrized by a single quantity per supercritical angular momentum channel. This low-energy parameter with the dimension of length is defined only up to multiplicative factors and thus each supercritical channel exhibits the discrete scale invariance. In particular, we show that the induced vacuum polarization has a power-law tail whose coefficient is a sum of log-periodic functions with respect to the distance from the potential center. This coefficient can also be expressed in terms of the energy and width of so-called atomic collapse resonances. Our universal predictions on the vacuum polarization and its relationship to atomic collapse resonances shed light on the longstanding fundamental problem of quantum electrodynamics and can in principle be tested by graphene experiments with charged impurities.

Nishida, Yusuke

2014-10-01

447

We study massless Dirac fermions in a supercritical Coulomb potential with the emphasis on that its low-energy physics is universal and parametrized by a single quantity per supercritical angular momentum channel. This low-energy parameter with the dimension of length is defined only up to multiplicative factors and thus each supercritical channel exhibits the discrete scale invariance. In particular, we show that the induced vacuum polarization has a power-law tail whose coefficient is a sum of log-periodic functions with respect to the distance from the potential center. This coefficient can also be expressed in terms of the energy and width of so-called atomic collapse resonances. Our universal predictions on the vacuum polarization and its relationship to atomic collapse resonances shed new light on the longstanding fundamental problem of quantum electrodynamics and can in principle be tested by graphene experiments with charged impurities.

Yusuke Nishida

2014-05-24

448

We study massless Dirac fermions in a supercritical Coulomb potential with the emphasis on that its low-energy physics is universal and parametrized by a single quantity per supercritical angular momentum channel. This low-energy parameter with the dimension of length is defined only up to multiplicative factors and thus each supercritical channel exhibits the discrete scale invariance. In particular, we show that the induced vacuum polarization has a power-law tail whose coefficient is a sum of log-periodic functions with respect to the distance from the potential center. This coefficient can also be expressed in terms of the energy and width of so-called atomic collapse resonances. Our universal predictions on the vacuum polarization and its relationship to atomic collapse resonances shed new light on the longstanding fundamental problem of quantum electrodynamics and can in principle be tested by graphene experiments with charged impurities.

Nishida, Yusuke

2014-01-01

449

Leptogenesis and Yukawa textures

We study a set of textures giving rise to correct masses and mixings of the charged fermions in the context of leptogenesis. The Dirac neutrino texture pattern is assumed to be identical with the up quark texture. The heavy Majonana neutrino mass matrix is obtained by inverting the type-I see-saw formula and using the neutrino masses and mixings required by the solar and atmospheric neutrino oscillation experiments as input. After making the feasibility study of the generated lepton asymmetry via the decay of the heavy right handed neutrino, we compute the generated baryon asymmetry by numerically solving the supersymmetric Boltzmann equations. We find for these models that both the hierarchy of the texture as well as the placement of the texture zeros are important to the viability of leptogenesis as the source of the observed baryon asymmetry of the universe.

Micheal S. Berger; Biswajoy Brahmachari

1999-03-18

450

Resonant Auger decay driving intermolecular Coulombic decay in molecular dimers.

In 1997, it was predicted that an electronically excited atom or molecule placed in a loosely bound chemical system (such as a hydrogen-bonded or van-der-Waals-bonded cluster) could efficiently decay by transferring its excess energy to a neighbouring species that would then emit a low-energy electron. This intermolecular Coulombic decay (ICD) process has since been shown to be a common phenomenon, raising questions about its role in DNA damage induced by ionizing radiation, in which low-energy electrons are known to play an important part. It was recently suggested that ICD can be triggered efficiently and site-selectively by resonantly core-exciting a target atom, which then transforms through Auger decay into an ionic species with sufficiently high excitation energy to permit ICD to occur. Here we show experimentally that resonant Auger decay can indeed trigger ICD in dimers of both molecular nitrogen and carbon monoxide. By using ion and electron momentum spectroscopy to measure simultaneously the charged species created in the resonant-Auger-driven ICD cascade, we find that ICD occurs in less time than the 20?femtoseconds it would take for individual molecules to undergo dissociation. Our experimental confirmation of this process and its efficiency may trigger renewed efforts to develop resonant X-ray excitation schemes for more localized and targeted cancer radiation therapy. PMID:24362568

Trinter, F; Schöffler, M S; Kim, H-K; Sturm, F P; Cole, K; Neumann, N; Vredenborg, A; Williams, J; Bocharova, I; Guillemin, R; Simon, M; Belkacem, A; Landers, A L; Weber, Th; Schmidt-Böcking, H; Dörner, R; Jahnke, T

2014-01-30

451

Influence of Coulomb collisions on the structure of reconnection layers

The influence of Coulomb collisions on the structure of reconnection layers is examined in neutral sheet geometry using fully kinetic simulations with a Monte Carlo treatment of the Fokker-Planck operator. The algorithm is first carefully benchmarked against key predictions from transport theory, including the parallel and perpendicular resistivities as well as the thermal force. The results demonstrate that the collisionality is accurately specified, thus allowing the initial Lundquist number to be chosen as desired. For modest Lundquist numbers S < or approx. 1000, the classic Sweet-Parker solution is recovered. Furthermore, a distinct transition to a faster kinetic regime is observed when the thickness of the resistive layer {delta}{sub SP} falls below the ion inertial length d{sub i}. For higher Lundquist numbers S > or approx. 1000, plasmoids