For comprehensive and current results, perform a real-time search at Science.gov.

1

NSDL National Science Digital Library

Plot of the Yukawa potential showing the hard=core formulation of the Yukawa Potential for several combinations of ? and ?. 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

NASA Astrophysics Data System (ADS)

In this paper, we present the approximate bound state solutions of the Dirac equation within the framework of spin and pseudospin symmetries for Eckart potential for arbitrary ?—state using Nikiforov-Uvarov method. The tensor interactions of Coulomb-like and Yukawa-like form are considered and the effects of these tensors and the degeneracy removing role are discussed in detail. Numerical results and figures to show the effect of the tensor interactions are also reported.

Ikot, Akpan N.; Maghsoodi, Elham; Zarrinkamar, Saber; Naderi, Leyla; Hassanabadi, Hassan

2014-04-01

5

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

6

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

7

Using the Screened Coulomb Potential to Illustrate the Variational Method

ERIC Educational Resources Information Center

The screened Coulomb potential, or Yukawa potential, is used to illustrate the application of the single and linear variational methods. The trial variational functions are expressed in terms of Slater-type functions, for which the integrals needed to carry out the variational calculations are easily evaluated in closed form. The variational…

Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

2012-01-01

8

We approximately solve the Dirac equation for the inversely quadratic Yukawa (IQY) potential including a Coulomb-like tensor potential with arbitrary spin-orbit coupling quantum number . In the framework of the spin and pseudospin (pspin) symmetry, we obtain the energy eigenvalue equation and the corresponding eigenfunctions in closed form by using the Nikiforov-Uvarov method. The numerical results show that the Coulomb-like tensor interaction removes degeneracies between spin and pspin state doublets.

Majid Hamzavi; Sameer M. Ikhdair; B. I. Ita

2012-03-30

9

Revision of FMM-Yukawa: An adaptive fast multipole method for screened Coulomb interactions

NASA Astrophysics Data System (ADS)

FMM-YUKAWA is a mathematical software package primarily for rapid evaluation of the screened Coulomb interactions of N particles in three dimensional space. Since its release, we have revised and re-organized the data structure, software architecture, and user interface, for the purpose of enabling more flexible, broader and easier use of the package. The package and its documentation are available at http://www.fastmultipole.org/, along with a few other closely related mathematical software packages. New version program summaryProgram title: FMM-Yukawa Catalogue identifier: AEEQ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEQ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL 2.0 No. of lines in distributed program, including test data, etc.: 78 704 No. of bytes in distributed program, including test data, etc.: 854 265 Distribution format: tar.gz Programming language: FORTRAN 77, FORTRAN 90, and C. Requires gcc and gfortran version 4.4.3 or later Computer: All Operating system: Any Classification: 4.8, 4.12 Catalogue identifier of previous version: AEEQ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 180 (2009) 2331 Does the new version supersede the previous version?: Yes Nature of problem: To evaluate the screened Coulomb potential and force field of N charged particles, and to evaluate a convolution type integral where the Green's function is the fundamental solution of the modified Helmholtz equation. Solution method: The new version of fast multipole method (FMM) that diagonalizes the multipole-to-local translation operator is applied with the tree structure adaptive to sample particle locations. Reasons for new version: To handle much larger particle ensembles, to enable the iterative use of the subroutines in a solver, and to remove potential contention in assignments for parallelization. Summary of revisions: The software package FMM-Yukawa has been revised and re-organized in data structure, software architecture, programming methods, and user interface. The revision enables more flexible use of the package and economic use of memory resources. It consists of five stages. The initial stage (stage 1) determines, based on the accuracy requirement and FMM theory, the length of multipole expansions and the number of quadrature points for diagonalization, and loads the quadrature nodes and weights that are computed off line. Stage 2 constructs the oct-tree and interaction lists, with adaptation to the sparsity or density of particles and employing a dynamic memory allocation scheme at every tree level. Stage 3 executes the core FMM subroutine for numerical calculation of the particle interactions. The subroutine can now be used iteratively as in a solver, while the particle locations remain the same. Stage 4 releases the memory allocated in Stage 2 for the adaptive tree and interaction lists. The user can modify the iterative routine easily. When the particle locations are changed such as in a molecular dynamics simulation, stage 2 to 4 can also be used together repeatedly. The final stage releases the memory space used for the quadrature and other remaining FMM parameters. Programs at the stage level and at the user interface are re-written in the C programming language, while most of the translation and interaction operations remain in FORTRAN. As a result of the change in data structures and memory allocation, the revised package can accommodate much larger particle ensembles while maintaining the same accuracy-efficiency performance. The new version is also developed as an important precursor to its parallel counterpart on multi-core or many core processors in a shared memory programming environment. Particularly, in order to ensure mutual exclusion in concurrent updates without incurring extra latency, we have replaced all the assignment statements at a source box that put its data to multiple target boxes with assignments at every target box that gather data from source boxes. This amounts to replacing t

Zhang, Bo; Huang, Jingfang; Pitsianis, Nikos P.; Sun, Xiaobai

2010-12-01

10

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

11

Observational Evidence for Dark Matter Interacting through a Yukawa Potential

NASA Astrophysics Data System (ADS)

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.

2013-05-01

12

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

13

NASA Astrophysics Data System (ADS)

We employ classical molecular dynamics (MD) to investigate species diffusivity in binary Yukawa mixtures. The Yukawa potential is used to describe the screened Coulomb interaction between the ions, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We use Green-Kubo techniques to calculate self-diffusivities and the Maxwell-Stefan diffusivities, and evaluate the validity of the Darken relation over a range of thermodynamic conditions of the mixture. The inter-diffusivity (or mutual diffusivity) can then be related to the Maxwell-Stefan diffusivities through the thermodynamic factor. The latter requires knowledge of the equation of state of the mixture. To test these Green-Kubo approaches and to estimate the activity contribution we have also employed large-scale non-equilibrium MD. In these simulations we can extract the inter-diffusivity value by calculating the rate of broadening of the interface in a diffusion couple. We also explore thermodynamic conditions for possible non-Fickian diffusivity. The main motivation in this work is to build a model that describes the transport coefficients in binary Yukawa mixtures over a broad range of thermodynamic conditions up to 1keV.

Haxhimali, Tomorr; Rudd, Robert; Jackson, Julie; Surh, Michael; Cabot, William; Caspersen, Kyle; Greenough, Jeffrey; Graziani, Frank; Miller, Paul

2012-10-01

14

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

15

Auxiliary basis sets to approximate Coulomb potentials

We demonstrate accuracy and computational efficiency resulting from an approximate treatment of Coulomb operators which is based on the expansion of molecular electron densities in atom-centered auxiliary basis sets. This is of special importance in density functional methods which separate the treatment of Coulomb and exchange-correlation terms. Auxiliary basis sets are optimized as much as possible for isolated atoms and

Karin Eichkorn; Oliver Treutler; Holger Öhm; Marco Häser; Reinhart Ahlrichs; Marco Ser

1995-01-01

16

Structural arrest transitions in fluids described by two Yukawa potentials.

We study a model colloidal system where particles interact via short-range attractive and long-range repulsive Yukawa potentials. Using the structure factor calculated from the mean-spherical approximation as the input, the kinetic phase diagrams as functions of the attraction depth and the volume fraction are obtained by calculating the Debye-Waller factors in the framework of the mode-coupling theory for three different heights of the repulsive barrier. The glass-glass reentrance phenomenon in the attractive colloidal case is also observed in the presence of the long-range repulsive barrier, which results in the lower and upper glass regimes. Competition between the short-range attraction and the long-range repulsion gives rise to new regimes associated with clusters such as "static cluster glass" and "dynamic cluster glass," which appear in the lower glass regime. Along the liquid-glass transition line between the liquid regime and the lower glass regime, crossover points separating different glass states are identified. PMID:15600578

Wu, Jianlan; Liu, Yun; Chen, Wei-Ren; Cao, Jianshu; Chen, Sow-Hsin

2004-11-01

17

Positron scattering from hydrogen atom with screened Coulomb potentials

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

Ghoshal, Arijit [Department of Mathematics, Burdwan University, Golapbag, Burdwan 713 104, West Bengal, India and Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nayek, Sujay [Department of Mathematics, Burdwan University, Golapbag, Burdwan 713 104, West Bengal (India); Kamali, M. Z. M. [Centre for Foundation Studies in Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ratnavelu, K. [Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2014-03-05

18

Glass-transition properties of Yukawa potentials: from charged point particles to hard spheres.

The glass transition is investigated in three dimensions for single and double Yukawa potentials for the full range of control parameters. For vanishing screening parameter, the limit of the one-component plasma is obtained; for large screening parameters and high coupling strengths, the glass-transition properties cross over to the hard-sphere system. Between the two limits, the entire transition diagram can be described by analytical functions. Unlike other potentials, the glass-transition and melting lines for Yukawa potentials are found to follow shifted but otherwise identical curves in control-parameter space. PMID:25019902

Yazdi, Anoosheh; Ivlev, Alexei; Khrapak, Sergey; Thomas, Hubertus; Morfill, Gregor E; Löwen, Hartmut; Wysocki, Adam; Sperl, Matthias

2014-06-01

19

Superintegrability of generalized Calogero models with oscillator or Coulomb potential

NASA Astrophysics Data System (ADS)

We deform N -dimensional (Euclidean, spherical and hyperbolic) oscillator and Coulomb systems, replacing their angular degrees of freedom by those of a generalized rational Calogero model. Using the action-angle description, it is established that maximal superintegrability is retained. For the rational Calogero model with Coulomb potential, we present all constants of motion via matrix model reduction. In particular, we construct the analog of the Runge-Lenz vector.

Hakobyan, Tigran; Lechtenfeld, Olaf; Nersessian, Armen

2014-11-01

20

Planar Massless Fermions in Coulomb and Aharonov-Bohm Potentials

NASA Astrophysics Data System (ADS)

Solutions to the Dirac equation are constructed for a massless charged fermion in Coulomb and Aharonov-Bohm (AB) potentials in 2+1 dimensions. The Dirac Hamiltonian on this background is singular and needs a one-parameter self-adjoint extension, which can be given in terms of self-adjoint boundary conditions. We show that the virtual (quasistationary) bound states emerge in the presence of an attractive Coulomb potential when the so-called effective charges become overcritical and discuss a restructuring of the vacuum of the quantum electrodynamics when the virtual bound states emerge. We derive equations, which determine the energies and lifetimes of virtual bound states, find solutions of obtained equations for some values of parameters as well as analyze the local density of states (LDOS) as a function of energy in the presence of Coulomb and AB potentials.

Khalilov, V. R.; Lee, K. E.

2012-11-01

21

Planar massless fermions in Coulomb and Aharonov-Bohm potentials

Solutions to the Dirac equation are constructed for a massless charged fermion in Coulomb and Aharonov--Bohm potentials in 2+1 dimensions. The Dirac Hamiltonian on this background is singular and needs a one-parameter self-adjoint extension, which can be given in terms of self-adjoint boundary conditions. We show that the virtual (quasistationary) bound states emerge in the presence of an attractive Coulomb potential when the so-called effective charges become overcritical and discuss a restructuring of the vacuum of the quantum electrodynamics when the virtual bound states emerge. We derive equations, which determine the energies and lifetimes of virtual bound states, find solutions of obtained equations for some values of parameters as well as analyze the local density of states as a function of energy in the presence of Coulomb and Aharonov--Bohm potentials.

Khalilov, V R

2013-01-01

22

Dirac Electron in Aharonov-Bohm and Planar Coulomb Potentials

Exact analytic solutions are found to the Dirac equation in (2+1) dimensions for a combination of Aharonov-Bohm and Lorentz 3-vector Coulomb potentials. By means of solutions obtained the relativistic Aharonov-Bohm effect is studied for free and bound electron states.

V. R. Khalilov

2004-01-01

23

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

24

Discrete perturbation theory for the hard-core attractive and repulsive Yukawa potentials

NASA Astrophysics Data System (ADS)

In this work we apply the discrete perturbation theory [A. L. Benavides and A. Gil-Villegas, Mol. Phys. 97, 1225 (1999)] to obtain an equation of state for the case of two continuous potentials: the hard-core attractive Yukawa potential and the hard-core repulsive Yukawa potential. The main advantage of the presented equation of state is that it is an explicit analytical expression in the parameters that characterize the intermolecular interactions. With a suitable choice of their inverse screening length parameter one can model the behavior of different systems. This feature allows us to make a systematic study of the effect of the variation in the parameters on the thermodynamic properties of this system. We analyze single phase properties at different conditions of density and temperature, and vapor-liquid phase diagrams for several values of the reduced inverse screening length parameter within the interval ??=0.1-5.0. The theoretical predictions are compared with available and new Monte Carlo simulation data. Good agreement is found for most of the cases and better predictions are found for the long-range ones. The Yukawa potential is an example of a family of hard-core plus a tail (attractive or repulsive) function that asymptotically goes to zero as the separations between particles increase. We would expect that similar results could be found for other potentials with these characteristics.

Torres-Arenas, J.; Cervantes, L. A.; Benavides, A. L.; Chapela, G. A.; del Río, F.

2010-01-01

25

Dirac fermion in planar Coulomb and Aharonov--Bohm potentials

Exact analytic solutions and the eigenenergies are found for the Dirac equation in 2+1 dimensions for a spin-one-half particle in a combination of the Lorentz 3-vector and scalar Coulomb as well as Aharonov--Bohm potentials. We employ the two-component Dirac equation which contains a new parameter introduced by Hagen to describe the spin of the spin-1/2 particle. We derive a transcendental equations that implicitly determine the energy spectrum of an electron near the negative-energy continuum boundary and the critical charges for some electron states. Fermion pair production from a vacuum by a strong Coulomb field in the presence of the magnetic flux tube of zero radius is considered. It is shown that the presence of the Ahanorov--Bohm flux tends to stabilize the system.

Khalilov, V R

2007-01-01

26

Reduced form for Coulomb-wave multicenter integrals

In a previous paper (J. C. Straton, Phys. Rev. A 41, 71 (1990)) an integro-differential transform was introduced and utilized to obtain the analytically reduced form for multicenter integrals composed of general-state hydrogenic orbitals, Yukawa or Coulomb potentials, and plane waves. The present paper extends this result to include Coulomb waves.

Straton, J.C. (Department of Physics, Cardwell Hall, Kansas State University, Manhattan, KS (USA))

1990-07-01

27

Coulomb holes and correlation potentials in the helium atom

In this paper we investigate Coulomb correlation effects in the He atom by studying the structure of the static and dynamic Coulomb hole charge distributions as determined by the analytical 39-parameter correlated wave function of Kinoshita. The static Coulomb hole, which is defined in terms of the radial electron-electron distribution function, shows that as a result of Coulomb repulsion there

Marlina Slamet; Viraht Sahni

1995-01-01

28

Three-loop Standard Model effective potential at leading order in strong and top Yukawa couplings

NASA Astrophysics Data System (ADS)

I find the three-loop contribution to the effective potential for the Standard Model Higgs field, in the approximation that the strong and top Yukawa couplings are large compared to all other couplings, using dimensional regularization with modified minimal subtraction. Checks follow from gauge invariance and renormalization group invariance. I also briefly comment on the special problems posed by Goldstone boson contributions to the effective potential, and on the numerical impact of the result on the relations between the Higgs vacuum expectation value, mass, and self-interaction coupling.

Martin, Stephen P.

2014-01-01

29

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

30

Cores in dwarf galaxies from dark matter with a Yukawa potential.

We show that cold dark matter particles interacting through a Yukawa potential could naturally explain the recently observed cores in dwarf galaxies without affecting the dynamics of objects with a much larger velocity dispersion, such as clusters of galaxies. The velocity dependence of the associated cross section as well as the possible exothermic nature of the interaction alleviates earlier concerns about strongly interacting dark matter. Dark matter evaporation in low-mass objects might explain the observed deficit of satellite galaxies in the Milky Way halo and have important implications for the first galaxies and reionization. PMID:21635025

Loeb, Abraham; Weiner, Neal

2011-04-29

31

NASA Astrophysics Data System (ADS)

The Ecker-Weizel approximation technique is applied to the Schrödinger equation for a class of screened Coulomb potentials (Yukawa, Exponential cosine screened Coulomb and Hulthén) for any arbitrary angular momentum l. We find that the centrifugal term can be combined with the central screening potential to generate an effective Eckart potential with energy dependent strength parameters for which the s-wave Schrödinger equation is exactly solvable. Using this effective s-wave potential in the formalism of Fuda and Whiting for off-shell analysis, we obtain a closed expression for the off-shell Jost solution fS,l (k,q,r) in which k is the on-shell momentum, q is the off-shell momentum and the subscript S means screening. It turns out that for nonzero angular momentum, usual Jost function fS,l (k,q) can not be defined for finite screening parameter ?. However, we find that the Jost solution, as well as the Jost function defined in the limit ? ? 0, show discontinuities at the on-shell point q=k, similar to the observation made by van Haeringen [Phys. Rev. A 18, 56 (1978)] for the s-wave Hulthén potential. For the l=0 case, we obtain explicit expressions for the off-shell and on-shell Jost solutions and Jost functions which possess the limiting behaviors discussed by van Haeringen for the Hulthén potential only. Our results not only extend previous works to higher partial waves, but at the same time indicate that certain limiting properties of the Jost solutions and the Jost functions are generally true for a class of screened Coulomb potentials.

Dutt, Ranabir; Varshni, Y. P.

1983-12-01

32

Renormalon Cancellation and Perturbative QCD Potential as a COULOMB+LINEAR Potential

NASA Astrophysics Data System (ADS)

Recently evidence has been found that the perturbative QCD potential agrees well with phenomenological potentials and lattice computations of the QCD potential. We discuss the present status of the perturbative QCD potential and theoretical backgrounds. We also report our recent analysis which shows analytically, on the basis of renormalon dominance picture, that the perturbative QCD potential quickly "converges" to a Coulomb-plus-linear form. The Coulomb-plus-linear potential can be computed systematically as we include more terms of the perturbative series; up to three-loop running (our current best knowledge), it shows a convergence towards lattice results. e.g. At one-loop running, the linear potential is ?r with ? = ( {{{2? CF } {/ {{2? CF } {? 0 }}} ; . } {? 0 }}} ; )? {2 / {{MS}}} .

Sumino, Y.

2004-04-01

33

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

34

Visualization of the effective potential and Coulomb correlations in finite metallic systems

Visualization of the effective potential and Coulomb correlations in finite metallic systems F visualization of the variations of both screening and Coulomb correlations with changes of location that can be visualized is an important part of understanding physical phenomena. Pre- sently

Berry, R. Stephen

35

Relativistic Aharonov-Bohm effect in the presence of planar Coulomb potentials

Exact analytic solutions are found to the Dirac equation in 2+1 dimensions for a combination of an Aharonov-Bohm potential and the Lorentz three-vector and scalar Coulomb potentials. By means of the solutions obtained the relativistic quantum Aharonov-Bohm effect is studied for the free (in the presence of a Lorentz three-vector Coulomb potential) and bound fermion states. We obtain the total

V. R. Khalilov

2005-01-01

36

Crystallization limits of the two-term Yukawa potentials based on the entropy criterion.

We examine the fluid-solid transition for the potential with two Yukawa terms (one attractive and the other repulsive) and a hard core by exploration of the parameter space of (K(1), Z(1), and Z(2)), i.e., the parameters of interaction strength and interaction ranges, respectively. We apply the single-phase crystallization rule of Giaquinta and Giunta (1992) by searching for the conditions where the residual entropy reaches zero. To obtain accurate entropy properties, we adopt the self-consistent closure theory of the zero-separation genre. This closure gives accurate thermodynamic properties. The Ornstein-Zernike equation is solved to obtain the correlation functions. The structure factor S(q) is examined with respect to its cluster-cluster peak, whose value is another indication of phase transition according to Hansen and Verlet (1969). We discover that the parameter Z(1) (which determines the range of attractive forces) is important in crystal formation, so long as sufficient attraction (parameter K(1)) is present. If the range of attraction is too narrow, strength alone is not adequate to satisfy the Giaquinta rule or to solidify at given concentration and temperature. The control of the range of repulsion rests with the Z(2)-parameter. Its variations can bring about a high peak in S(q) at zero wave number (i.e., at q=0). Implications for the crystallization of protein and colloidal solutions are discussed. PMID:20170235

Lee, Lloyd L; Hara, Michael C; Simon, Steven J; Ramos, Franklin S; Winkle, Andrew J; Bomont, Jean-Marc

2010-02-21

37

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

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

Khalilov, V

2004-01-01

38

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

We obtain exact solutions to the Dirac equation and the relevant binding\\u000aenergies in the combined Aharonov--Bohm--Coulomb potential in 2+1 dimensions.\\u000aBy means of solutions obtained the quantum Aharonov--Bohm effect is studied for\\u000afree and bound electron states. We show that the total scattering amplitude in\\u000athe combined Aharonov--Bohm--Coulomb potential is a sum of the Aharonov--Bohm\\u000aand the Coulomb scattering

Vladislav Khalilov

2004-01-01

39

NASA Astrophysics Data System (ADS)

In this paper, we obtain the approximate analytical bound-state solutions of the Dirac particle with the generalized Yukawa potential within the framework of spin and pseudospin symmetries for the arbitrary ? state with a generalized tensor interaction. The generalized parametric Nikiforov-Uvarov method is used to obtain the energy eigenvalues and the corresponding wave functions in closed form. We also report some numerical results and present figures to show the effect of the tensor interaction.

Ikot, Akpan N.; Maghsoodi, Elham; Hassanabadi, Hassan; Obu, Joseph A.

2014-05-01

40

Calculation of Transport Coefficients in Binary Yukawa Mixtures

NASA Astrophysics Data System (ADS)

We employ classical molecular dynamics (MD) to estimate species diffusivity and viscosity in binary Yukawa Mixtures. The Yukawa potential is used to describe the screened Coulomb interaction between the ions, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We calculate transport coefficients in equilibrium simulations using the Green-Kubo relation over a range of thermodynamic conditions including the viscosity and the self-diffusivity for each component of the mixture. The inter-diffusivity (or mutual diffusivity) can then be related to the self-diffusivities by using a generalization of the Darken equation. We have also employed non-equilibrium MD to estimate inter-diffusivity during the broadening of the interface between two regions each with a high concentration of either species. The main motivation in this work is to build a model that describes the transport coefficients in binary Yukawa mixtures over a broad range of thermodynamic conditions.

Haxhimali, Tomorr; Rudd, Robert

2012-02-01

41

Relativistic Aharonov-Bohm effect in the presence of planar Coulomb potentials

NASA Astrophysics Data System (ADS)

Exact analytic solutions are found to the Dirac equation in 2+1 dimensions for a combination of an Aharonov-Bohm potential and the Lorentz three-vector and scalar Coulomb potentials. By means of the solutions obtained the relativistic quantum Aharonov-Bohm effect is studied for the free (in the presence of a Lorentz three-vector Coulomb potential) and bound fermion states. We obtain the total scattering amplitude in a combination of the Aharonov-Bohm and Lorentz three-vector Coulomb potentials as a sum of two scattering amplitudes. This modifies the expression for the standard Aharonov-Bohm cross section due to the interference of these two amplitudes with each other. We discuss that the observable quantities can be the phases of electron wave functions or the energies of bound states.

Khalilov, V. R.

2005-01-01

42

Creation of planar charged fermions in Coulomb and Aharonov-Bohm potentials

NASA Astrophysics Data System (ADS)

The creation of charged fermions from the vacuum by a Coulomb field in the presence of an Aharonov-Bohm (AB) potential are studied in 2+1 dimensions. The process is governed by a (singular) Dirac Hamiltonian that requires the supplementary definition in order for it to be treated as a self-adjoint quantum-mechanical operator. By constructing a one-parameter self-adjoint extension of the Dirac Hamiltonian, specified by boundary conditions, we describe the (virtual bound) quasistationary states with "complex energy" emerging in an attractive Coulomb potential, derive for the first time, complex equations (depending upon the electron spin and the extension parameter) for the quasistationary state "complex energy". The constructed self-adjoint Dirac Hamiltonians in Coulomb and AB potentials are applied to provide a correct description to the low-energy electron excitations, as well as the creation of charged quasiparticles from the vacuum in graphene by the Coulomb impurity in the presence of AB potential. It is shown that the strong Coulomb field can create charged fermions for some range of the extension parameter.

Khalilov, V. R.

2013-08-01

43

The usual approximation scheme is used to study the solution of the Duffin-Kemmer-Petiau (DKP) equation for a vector Yukawa potential in the framework of the parametric Nikiforov-Uvarov (NU) method. The approximate energy eigenvalue equation and the corresponding wave function spinor components are calculated for arbitrary total angular momentum in closed form. Further, the approximate energy equation and wave function spinor components are also given for case. A set of parameter values is used to obtain the numerical values for the energy states with various values of quantum levels

Hamzavi, Majid

2012-01-01

44

Force field and potential due to the Fermi-Coulomb hole charge for nonspherical-density atoms

In the work formalism for the determination of electronic structure, the exchange-correlation energy and (local) potential of the electrons both arise via Coulomb's law from the same source, viz., the quantum-mechanical Fermi-Coulomb hole charge. The potential is the work Wxc(r) done to move an electron in the field of its Fermi-Coulomb hole and the energy is the interaction energy between

Marlina Slamet; Viraht Sahni; Manoj K. Harbola

1994-01-01

45

Exact solutions to the Dirac equation with a Coulomb potential in 2+1 dimensions

The (2+1)-dimensional Dirac equation with a Coulomb potential is investigated by studying a second-order differential equation obtained from a pair of coupled first-order ones. The solutions of the bound states expressed by the confluent hypergeometric functions are analytically obtained. The energy levels and their fine structures are also presented.

Shi-Hai Dong; Zhong-Qi Ma

2003-01-01

46

Creation of planar charged fermions in Coulomb and Aharonov-Bohm potentials

The creation of charged fermions from the vacuum by a Coulomb field in the presence of an Aharonov--Bohm (AB) potential are studied in 2+1 dimensions. The process is governed by a (singular) Dirac Hamiltonian that requires the supplementary definition in order for it to be treated as a self-adjoint quantum-mechanical operator. By constructing a one-parameter self-adjoint extension of the Dirac Hamiltonian, specified by boundary conditions, we describe the (virtual bound) quasistationary states with "complex energy" emerging in an attractive Coulomb potential, derive for the first time, complex equations (depending upon the electron spin and the extension parameter) for the quasistationary state "complex energy". The constructed self-adjoint Dirac Hamiltonians in Coulomb and AB potentials are applied to provide a correct description to the low-energy electron excitations, as well as the creation of charged quasiparticles from the vacuum in graphene by the Coulomb impurity in the presence of AB potential. It is...

Khalilov, V R

2013-01-01

47

Exact Solutions of the Dirac Equation with a Coulomb Plus Scalar Potential in 2 + 1 Dimensions

The exact solutions of the (2+1)-dimensional Dirac equation with a Coulomb potential and a scalar one are analytically presented by studying the second-order differential equations obtained from a pair of coupled first-order ones. The eigenvalues are studied in some detail.

Shi-Hai Dong; Xiao-Yan Gu; Zhong-Qi Ma; Shishan Dong

2002-01-01

48

Supersymmetry and SWKB approach to the Dirac equation with a Coulomb potential in 2 + 1 dimensions

By using the supersymmetric quantum mechanics and shape invariance, the (2+1)-dimensional Dirac equation with a Coulomb potential is investigated. The solutions of the bound states expressed by the confluent hypergeometric functions are analytically obtained. The energy levels are also given by means of both supersymmetric quantum mechanics and supersymmetric WKB approach.

Wen Chao Qiang; Run Suo Zhou; Yang Gao

2004-01-01

49

Exact solutions to the Dirac equation with a Coulomb potential in /2+1 dimensions

NASA Astrophysics Data System (ADS)

The (2+1)-dimensional Dirac equation with a Coulomb potential is investigated by studying a second-order differential equation obtained from a pair of coupled first-order ones. The solutions of the bound states expressed by the confluent hypergeometric functions are analytically obtained. The energy levels and their fine structures are also presented.

Dong, Shi-Hai; Ma, Zhong-Qi

2003-06-01

50

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

51

Screened Coulomb potential in a flowing magnetized plasma

NASA Astrophysics Data System (ADS)

The electrostatic potential of a moving dust grain in a complex plasma with magnetized ions is computed using linear response theory, thereby extending our previous work for unmagnetized plasmas (Ludwig et al 2012 New J. Phys. 14 053016). In addition to the magnetic field, our approach accounts for a finite ion temperature as well as ion-neutral collisions. Our recently introduced code Kielstream is used for an efficient calculation of the dust potential. Increasing the magnetization of the ions, we find that the shape of the potential crucially depends on the Mach number M. In the regime of subsonic ion flow (M < 1), a strong magnetization gives rise to a potential distribution that is qualitatively different from the unmagnetized limit, while for M > 1 the magnetic field effectively suppresses the plasma wakefield.

Joost, J.-P.; Ludwig, P.; Kählert, H.; Arran, C.; Bonitz, M.

2015-02-01

52

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

53

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

2001-02-06

54

Virial theorem and Gibbs thermodynamic potential for Coulomb systems

Using the grand canonical ensemble and the virial theorem, we show that the Gibbs thermodynamic potential of the non-relativistic system of charged particles is uniquely defined by single-particle Green functions of electrons and nuclei. This result is valid beyond the perturbation theory with respect to the interparticle interaction.

Bobrov, V. B., E-mail: vic5907@mail.ru, E-mail: satron@mail.ru [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya St. 13, Bd. 2, Moscow 125412 (Russian Federation); National Research University “MPEI,” Krasnokazarmennaya str. 14, Moscow 111250 (Russian Federation); Trigger, S. A., E-mail: vic5907@mail.ru, E-mail: satron@mail.ru [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya St. 13, Bd. 2, Moscow 125412 (Russian Federation); Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, Berlin D-12489 (Germany)

2014-10-15

55

Zero-temperature phase diagram of Yukawa bosons

NASA Astrophysics Data System (ADS)

We study the zero-temperature phase diagram of bosons interacting via screened Coulomb (Yukawa) potential by means of the diffusion Monte Carlo method. The Yukawa potential is used as a model interaction in the neutron matter, dusty plasmas, and charged colloids. As shown by Petrov [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.99.130407 99, 130407 (2007)], interactions between weakly bound molecules of heavy and light fermionic atoms are described by an effective Yukawa potential with a strength related to the heavy-light mass ratio M/m, which might lead to crystallization in a two-dimensional geometry if the mass ratio of heavy-light fermions exceeds a certain critical value. In the present work we do a thorough study of the quantum three-dimensional Yukawa system. For strong interactions (equivalently, large mass ratios) the system experiences several phase transitions as the density is increased, passing from gas to solid and to gas phase again. Weakly interacting Yukawa particles do not crystallize at any density. We find the minimal interaction strength at which the crystallization happens. In terms of the two-component fermionic system, this strength corresponds to a heavy-light mass ratio of M/m˜180, so that it is impossible to realize the gas-crystal transition in a conventional bulk system. For the Yukawa model of fermionic mixtures we also analyze the possibility of building molecular systems with very large effective mass ratios by confining the heavy component to a sufficiently deep optical lattice. We show how the effective mass of the heavy component can be made arbitrarily large by increasing the lattice depth, thus leading to a tunable effective mass ratio that can be used to realize a molecular superlattice.

Osychenko, O. N.; Astrakharchik, G. E.; Mazzanti, F.; Boronat, J.

2012-06-01

56

The {sup 6}He Optical Potential at energies around the Coulomb barrier

We present an Optical Model (OM) study of {sup 6}He on {sup 208}Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (E{sub lab} = 14, 16, 18, 22, and 27 MeV)[1]. For the projectile-target bare interaction, we use the microscopic Sao Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the alpha channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the alpha particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

Fernandez-Garcia, J. P.; Alvarez, M. A. G. [Dpto. de FAMN, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla (Spain); CNA, Universidad de Sevilla, c/Thomas Alva Edison 7, 41092 Sevilla (Spain); Rodriguez-Gallardo, M. [Dpto. de FAMN, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla (Spain); Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain); Moro, A. M. [Dpto. de FAMN, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla (Spain)

2010-04-26

57

Zero-mass fermions in Coulomb and Aharonov-Bohm potentials in 2+1 dimensions

NASA Astrophysics Data System (ADS)

We consider the motion of a relativistic charged zero-mass fermion in Coulomb and Aharonov-Bohm potentials in 2+1 dimensions. With these singular external potentials, we construct one-parameter self-adjoint Dirac Hamiltonians classified by self-adjoint boundary conditions. We show that if the so-called effective charge becomes overcritical, then virtual (quasistationary) bound states occur. The wave functions corresponding to these states have large amplitudes near the Coulomb center, and their energy spectrum is quasidiscrete and consists of a number of broadened levels of a width related to the inverse lifetime of the quasistationary state. We derive equations for the quasidiscrete spectra and quasistationary state lifetimes and solve these equations in physically interesting cases. We study the so-called local densities of state, which can be assessed in physical experiments, as functions of the energy and the problem parameters, investigating these densities both analytically and graphically.

Khalilov, V. R.

2013-05-01

58

Approximate ?-state solutions to the Dirac-Yukawa problem based on the spin and pseudospin symmetry

NASA Astrophysics Data System (ADS)

Using an approximation scheme to deal with the centrifugal (pseudo-centrifugal) term, we solve the Dirac equation with the screened Coulomb (Yukawa) potential for any arbitrary spin-orbit quantum number ?. Based on the spin and pseudospin symmetry, analytic bound state energy spectrum formulas and their corresponding upper- and lower-spinor components of two Dirac particles are obtained using a shortcut of the Nikiforov-Uvarov method. We find a wide range of permissible values for the spin symmetry constant C s from the valence energy spectrum of particle and also for pseudospin symmetry constant C ps from the hole energy spectrum of antiparticle. Further, we show that the present potential interaction becomes less (more) attractive for a long (short) range screening parameter ?. To remove the degeneracies in energy levels we consider the spin and pseudospin solution of Dirac equation for Yukawa potential plus a centrifugal-like term. A few special cases such as the exact spin (pseudospin) symmetry Dirac-Yukawa, the Yukawa plus centrifugal-like potentials, the limit when ? becomes zero (Coulomb potential field) and the non-relativistic limit of our solution are studied. The nonrelativistic solutions are compared with those obtained by other methods.

Ikhdair, Sameer M.

2012-04-01

59

Fermion pair production in planar Coulomb and Aharonov--Bohm potentials

Exact analytic solutions are found for the Dirac equation in 2+1 dimensions for a spin-one-half particle in a combination of the Lorentz 3-vector and scalar Coulomb as well as Aharonov--Bohm potentials. We employ the two-component Dirac equation which contains a new parameter introduced by Hagen to describe the spin of the spin-1\\/2 particle. We derive a transcendental equations that implicitly

V. R. Khalilov; Choon-Lin Ho

2007-01-01

60

NASA Astrophysics Data System (ADS)

An exact analytical treatment is presented, in the momentum space, for the one-dimensional spinless Salpeter equation describing two particles with unequal masses interacting via a Coulomb-type potential. We derive the exact energy equation for bound states and work out the associated wave functions. The obtained energy eigenvalues are shown to agree very well with exact numerical calculations and also the analytical upper bounds available in the literature.

Chargui, Y.; Dhahbi, A.; Trabelsi, A.

2015-01-01

61

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

62

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

63

Proton radioactivity with a Yukawa effective interaction

NASA Astrophysics Data System (ADS)

The half-lives of proton radioactivity of proton emitters are investigated theoretically. Proton-nucleus interaction potentials are obtained by folding the densities of the daughter nuclei with a finite-range effective nucleon-nucleon interaction having Yukawa form. The Wood-Saxon density distributions for the nuclei used in calculating the nuclear as well as the Coulomb interaction potentials are predictions of the interaction. The quantum mechanical tunneling probability is calculated within the WKB framework. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes. The effects of neutron-proton effective mass splitting in neutron-rich asymmetric matter as well as the nuclear matter incompressibility on the decay probability are investigated.

Routray, T. R.; Tripathy, S. K.; Dash, B. B.; Behera, B.; Basu, D. N.

2011-08-01

64

Proton radioactivity with a Yukawa effective interaction

The half lives of proton radioactivity of proton emitters are investigated theoretically. Proton-nucleus interaction potentials are obtained by folding the densities of the daughter nuclei with a finite range effective nucleon-nucleon interaction having Yukawa form. The Wood-Saxon density distributions for the nuclei used in calculating the nuclear as well as the Coulomb interaction potentials are predictions of the interaction. The quantum mechanical tunneling probability is calculated within the WKB framework. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes. The effects of neutron-proton effective mass splitting in neutron rich asymmetric matter as well as the nuclear matter incompressibility on the decay probability are investigated.

T. R. Routray; S. K. Tripathy; B. B. Dash; B. Behera; D. N. Basu

2011-04-26

65

NASA Astrophysics Data System (ADS)

We introduce a new family of Hamiltonians with a deformed Kepler-Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wavefunctions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wavefunctions, and give the transformed integrals explicitly for the classical system.

Post, Sarah; Winternitz, Pavel

2010-06-01

66

On the Bound States of the Dirac Equation with a Coulomb Potential in 2+1 Dimensions

NASA Astrophysics Data System (ADS)

Solutions of the (2 + 1)-dimensional Dirac equation with a Coulomb potential are analytically obtained by studying Tricomi equations obtained from a pair of coupled first-order ones. The eigenvalues and their fine structures are also presented.

Dong, Shi-Hai

67

On the Bound States of the Dirac Equation with a Coulomb Potential in 2+1 Dimensions

Solutions of the (2 + 1)-dimensional Dirac equation with a Coulomb potential are analytically obtained by studying Tricomi equations obtained from a pair of coupled first-order ones. The eigenvalues and their fine structures are also presented.

Shi-Hai Dong

2003-01-01

68

NASA Astrophysics Data System (ADS)

We present a scheme for calculating the exact exchange energy in periodic solids within a Kohn Sham or Hartree Fock approach, which removes the need to treat the integrable singularities via an auxiliary function. In the exchange integrals, we use a modified Coulomb potential, which tends to the exact potential as the number of k points increases yet has no singularities, and which is also very simple to implement. We compare this approach to the auxiliary function scheme for diamond, graphite, and two allotropes of silicon carbide and show that it converges more rapidly with the number of wave vectors.

Spencer, James; Alavi, Ali

2008-05-01

69

Electron in the Aharonov-Bohm potential and in the Coulomb field in 2+1 dimensions

We obtain exact solutions of the Dirac equation in 2+1 dimensions and the electron energy spectrum in the superposition of\\u000a the Aharonov-Bohm and Coulomb potentials, which are used to study the Aharonov-Bohm effect for states with continuous and\\u000a discrete energy spectra. We represent the total scattering amplitude as the sum of amplitudes of scattering by the Aharonov-Bohm\\u000a and Coulomb potentials.

V. R. Khalilov

2006-01-01

70

Electron in the Aharonov-Bohm potential and in the Coulomb field in 2+1 dimensions

We obtain exact solutions of the Dirac equation in 2+1 dimensions and the electron energy spectrum in the superposition of the Aharonov-Bohm and Coulomb potentials, which are used to study the Aharonov-Bohm effect for states with continuous and discrete energy spectra. We represent the total scattering amplitude as the sum of amplitudes of scattering by the Aharonov-Bohm and Coulomb potentials.

V. R. Khalilov

2006-01-01

71

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

72

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

73

Green's function for motion in Coulomb-modified separable nonlocal potentials

A closed form expression is derived for the outgoing wave radial Green's function G-script/sup (+)//sub l-italic/ (r-italic,r-italic') for motion in the Coulomb plus rank one separable nonlocal potential with form factor v-italic/sub l-italic/(r-italic) = 2/sup -//sup l-italic/ x (l-italicexclamation)/sup -1/ r-italic/sup l-italic/e-italic/sup -//sup ..beta..//sup >//sup l-italic/r-italic$. Some possible applications of the result are discussed.

Talukdar, B.; Laha, U.; Sasakawa, T.

1986-08-01

74

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

2012-01-10

75

Exponential supercell convergence of the exact exchange energy via truncated coulomb potentials

NASA Astrophysics Data System (ADS)

Hybrid density functionals have become increasingly popular as a solution to mitigate the self-interaction error in semi-local density functionals, but widespread application to periodic systems has been limited by computational cost. This cost is exacerbated by poor k-point convergence due to the G->0 singularity in the exact exchange energy, in spite of several singularity correction methods such as auxilliary function integration,footnotetextP. Carrier, S. Rohra and A. G"orling, Phys. Rev. B 75, 205126 (2007)^,footnotetextI. Duchemin and F. Gygi, Comp. Phys. Comm 181, 855 (2010) image subtraction,footnotetextJ. Paier et al., J. Chem. Phys. 122, 234102 (2005) and spherical truncation of the coulomb potential.footnotetextJ. Spencer and A. Alavi, Phys. Rev. B 77, 193110 (2008) We analyze these rather disparate methods in an intuitive formalism based on Wannier function localization, which naturally suggests the truncation of the Coulomb potential on the superlattice Wigner-Seitz cell. We demonstrate that this scheme systematically exhibits the best k-point convergence, comparable to that of semi-local functionals, even for low-symmetry and reduced-periodicity systems where previous methods fail.

Sundararaman, Ravishankar; Arias, T. A.

2013-03-01

76

Dynamics of H{{e}^{2+}}+H ionization with exponential cosine-screened Coulomb potential

NASA Astrophysics Data System (ADS)

Dynamics of H{{e}^{2+}}+H ionization in dense quantum plasmas (DQPs) has been studied by the classical trajectory Monte Carlo method. The interactions between charged particles have been described by the exponential cosine-screened Coulomb potential. It is found that ionization cross sections in plasma environments are obviously larger than those in plasma-free environments due to the screening effects. Cross sections for {{H}^{+}} also have been calculated for comparison. For {{H}^{+}}, cross sections increase with the increase of screening effects. However, for H{{e}^{2+}}, cross sections begin to decrease in strong screening effects at intermediate energies. Furthermore, H{{e}^{2+}} impact ionization cross sections in weakly coupled plasmas (WCPs) also have been calculated. The interactions have been described by the static screened Coulomb potential. It is found that when screening effects are weak, cross sections in DQPs and WCPs are approximately the same. As screening effects increase, cross sections in DQPs become larger than those in WCPs at high energies. However, when screening effects are strong enough, cross sections in DQPs become smaller than those in WCPs at low and intermediate energies.

Zhang, Ling-yu; Qi, Xin; Zhao, Xiao-ying; Zhang, Xun-chao; Xiao, Guo-qing; Duan, Wen-shan; Yang, Lei

2014-08-01

77

NASA Astrophysics Data System (ADS)

The Dirac equation is solved to obtain its approximate bound states for a spin-1/2 particle in the presence of trigonometric Pöschl—Teller (tPT) potential including a Coulomb-like tensor interaction with arbitrary spin—orbit quantum number ? using an approximation scheme to substitute the centrifugal terms ?(? ± 1)r-2. In view of spin and pseudo-spin (p-spin) symmetries, the relativistic energy eigenvalues and the corresponding two-component wave functions of a particle moving in the field of attractive and repulsive tPT potentials are obtained using the asymptotic iteration method (AIM). We present numerical results in the absence and presence of tensor coupling A and for various values of spin and p-spin constants and quantum numbers n and ?. The non-relativistic limit is also obtained.

Babatunde, J. Falaye; Sameer, M. Ikhdair

2013-06-01

78

Competition between Coulomb and Symmetry Potential in Semi-peripheral Heavy-ion Collisions

The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system, $^{40}$Ar+$^{197}$Au, at b=6fm and $E_{beam}$=35, 50 and 100MeV/u, are investigated by using the Improved Quantum Molecular Dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant Y(n)/Y(p) ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of Y(n)/Y(p). This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.

Qianghua Wu; Yingxun Zhang; Zhigang Xiao; Rensheng Wang; Yang Zhang; Zhuxia Li; Ning Wang; R. H. Schowalter

2015-01-17

79

Competition between Coulomb and Symmetry Potential in Semi-peripheral Heavy-ion Collisions

The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system, $^{40}$Ar+$^{197}$Au, at b=6fm and $E_{beam}$=35, 50 and 100MeV/u, are investigated by using the Improved Quantum Molecular Dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant Y(n)/Y(p) ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of Y(n)/Y(p). This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.

Wu, Qianghua; Xiao, Zhigang; Wang, Rensheng; Zhang, Yang; Li, Zhuxia; Wang, Ning; Schowalter, R H

2015-01-01

80

NASA Astrophysics Data System (ADS)

We investigate the analytical approximation to arbitrary \\kappa -state solutions of the Dirac equation with the position-dependent mass particle in the Eckart potential including the Yukawa tensor interaction in the framework of a parametric Nikiforov-Uvarov method. By taking a proper approximation to deal with the centrifugal term, the analytical relativistic energy eigenvalues and the corresponding normalized two-spinor components of the wave function are obtained in closed form. The relativistic and non-relativistic bound state solutions for some special cases, such as the Hulthén potential and the generalized Morse potential, are easily obtained from our general solution.

Ikhdair, Sameer M.

2013-12-01

81

Spontaneous fermion creation in the coulomb field and Aharonov-Bohm potential in 2+1 dimensions

We find exact solutions of the Dirac equation and the fermion energy spectrum in the Coulomb ( vector and scalar) potential and Aharonov-Bohm potential in 2+1 dimensions taking the particle spin into account. We describe the fermion spin using the two-component Dirac equation with the additional ( spin) parameter introduced by Hagen. We consider the effect of creation of fermion

V. R. Khalilov

2009-01-01

82

Shape resonances in the electron-hydrogen system with screened Coulomb potentials

NASA Astrophysics Data System (ADS)

We investigate the shape resonances of the electron-hydrogen system embedded in Debye plasma environments modeled by screened Coulomb potentials. The complex-coordinate rotation method is employed to calculate the resonance parameters and the Hylleraas-type wave functions are used to represent the correlation effects of the two electrons. The 1Se resonance states of H- above the N=2-5 thresholds of H atom are investigated and the resonance parameters for a Debye length ranging from infinity to small values are reported. It is shown that the widths of the shape resonances lying above the H(N=4,5) thresholds exhibit some interesting behaviors in relatively strong screening situations. The possible reason for such phenomena is discussed.

Jiao, L. G.; Ho, Y. K.

2013-05-01

83

Programs were developed to calculate integrals involving spherical Bessel, spherical Neumann, and spherical Hankel functions needed for Kohn and complex Kohn variational scattering calculations. In particular, all types needed for a screened coulomb potential for all 1 were evaluated. Some of these integrals are expressable in closed form, whereas others must be expressed in terms of hypergeometric functions, which must be calculated numerically. In many instances, recursion procedures lead to quick and accurate evaluation of some related integrals. In most cases, the integrals were evaluated using several different procedures to allow accuracy checks on their numerical values. Agreement in the calculation of integrals using different methods was usually to at least six (6) places of accuracy.

Kinser, H.B. (Dalton College, GA (USA)); Crawford, O.H.

1990-01-01

84

Shear viscosity of two-dimensional Yukawa systems in liquid state

The shear viscosity of a two-dimensional (2D) liquid was calculated using equilibrium molecular dynamics simulations with a Yukawa potential. The shear viscosity has a minimum, at a Coulomb coupling parameter of about 17, arising from the temperature dependence of the kinetic and potential contributions. Previous calculations of 2D viscosity were less extensive, and for a different potential. The stress autocorrelation function was found to decay rapidly, contrary to some earlier work. These results are useful for 2D condensed matter systems and are compared to a recent dusty plasma experiment.

Bin Liu; J. Goree

2005-01-31

85

Fermions in scalar Coulomb and Aharonov-Bohm potentials in 2+1 dimensions

NASA Astrophysics Data System (ADS)

The quantum-mechanical problem of constructing the self-adjoint Hamiltonians is physically rigorously solved for a Dirac Hamiltonian with a Coulomb scalar potential and an Aharonov-Bohm potential in 2+1 dimensions by taking into account a fermion spin. It is found that the Dirac Hamiltonian on this background requires the additional specification of a one-parameter self-adjoint extension, which can be given in terms of the physically acceptable boundary conditions. We derive equations that determine the spectra of the self-adjoint radial Dirac Hamiltonians for various parameter values. We discuss the role of a particle spin as the physical reason of the existence of bound fermion states in a pure Aharonov-Bohm potential and show that the particle and antiparticle states with zero energy exist only owing to the interaction of the fermion spin magnetic moment with the magnetic field. The energy levels of particles and antiparticles are intersected what may signal on the instability of a quantum system.

Khalilov, V. R.; Lee, K. E.

2011-05-01

86

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. Fern?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. PMID:23406133

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

2013-02-01

87

Supersymmetry and SWKB approach to the Dirac equation with a Coulomb potential in 2+1 dimensions

NASA Astrophysics Data System (ADS)

By using the supersymmetric quantum mechanics and shape invariance, the (2+1)-dimensional Dirac equation with a Coulomb potential is investigated. The solutions of the bound states expressed by the confluent hypergeometric functions are analytically obtained. The energy levels are also given by means of both supersymmetric quantum mechanics and supersymmetric WKB approach.

Qiang, Wen Chao; Zhou, Run Suo; Gao, Yang

2004-11-01

88

Supersymmetry and SWKB approach to the Dirac equation with a Coulomb potential in 2+1 dimensions

By using the supersymmetric quantum mechanics and shape invariance, the (2+1)-dimensional Dirac equation with a Coulomb potential is investigated. The solutions of the bound states expressed by the confluent hypergeometric functions are analytically obtained. The energy levels are also given by means of both supersymmetric quantum mechanics and supersymmetric WKB approach.

Wen Chao Qiang; Run Suo Zhou; Yang Gao

2004-01-01

89

The Coulomb potential is screened by high density mobile deuterons more than the electrons in the PdDx deuteride, and the coherent motion of deuteron might play an important role for analysis of the low-energy nuclear reaction in condensed matter. Together with the group theoretical approach used in nuclear physics, the quantum field theory might provide a sound foundation for analysis

Hiroshi Takahashi

2005-01-01

90

NASA Astrophysics Data System (ADS)

Molecular dynamics (MD) simulations are performed to investigate the temperature relaxation between electrons and ions in a fully ionized, dense hydrogen plasma. We used HM (J. P. Hansen and I. R. McDonald) potential and introduced a truncated Coulomb interaction, which can avoid Coulomb catastrophe by choosing an appropriate cutting radius. The calculated results are compared with those from theoretical models (LS, GMS, BPS), whose applicability is also discussed. The effect of the interaction between ions and electrons on the temperature relaxation process is also investigated in the strong collision region. Finally, we discuss the effect of exchange interaction of electrons to the temperature relaxation.

Ma, Qian; Dai, Jiayu; Kang, Dongdong; Zhao, Zengxiu; Yuan, Jianmin; Zhao, Xueqing

2014-12-01

91

A Lennard-Jones plus Coulomb potential for Al3+ ions in aqueous solutions

NASA Astrophysics Data System (ADS)

We developed a simple pair-additive Lennard-Jones plus Coulomb potential for molecular simulations of the trivalent cation Al3+ in water which accounts reasonably well for the behavior of aluminum aqueous solutions. The model predicts an octahedral first hydration shell containing 6 water molecules and a trigonal second shell with 12 molecules on average, in good agreement with the available experimentally determined structure. The peak positions of the cation-oxygen radial distribution function are only slightly compressed compared to the x-ray structure, the hydration enthalpy is 10% too low, and the cation self-diffusion coefficient and the single-particle second rank reorientational time are in excellent agreement with inelastic neutron scattering and NMR spectroscopy data, respectively. The model also captures the essential vibrational features of the hydrated [Al(H2O)6]3+ complex. It predicts the main O-Al-O bending mode frequency to within ˜5%, but significantly overestimates the frequency of the totally symmetric Al-O stretching mode. Overall, the accuracy of the proposed model is as good as the best available classical potentials, if not better in some aspects, with a much simpler functional form, which makes it an attractive alternative for computer simulations of Al3+ in more complex aqueous and biomolecular systems.

Faro, Tatiana M. C.; Thim, Gilmar P.; Skaf, Munir S.

2010-03-01

92

Spontaneous fermion creation in the coulomb field and Aharonov-Bohm potential in 2+1 dimensions

We find exact solutions of the Dirac equation and the fermion energy spectrum in the Coulomb (vector and scalar) potential and Aharonov-Bohm potential in 2+1 dimensions taking the particle spin into account. We describe the fermion spin using the two-component Dirac equation with\\u000a the additional (spin) parameter introduced by Hagen. We consider the effect of creation of fermion pairs from

V. R. Khalilov

2009-01-01

93

Analytic structure of the multichannel Jost matrix for potentials with Coulombic tails

A quantum system is considered that can move in N two-body channels with the potentials that may include the Coulomb interaction. For this system, the Jost matrix is constructed in such a way that all its dependencies on the channel momenta and Sommerfeld parameters are factorized in the form of explicit analytic expressions. It is shown that the two remaining unknown matrices are single-valued analytic functions of the energy and therefore can be expanded in the Taylor series near an arbitrary point within the domain of their analyticity. It is derived a system of first-order differential equations whose solutions determine the expansion coefficients of these series. Alternatively, the unknown expansion coefficients can be used as fitting parameters for parametrizing experimental data similarly to the effective-range expansion. Such a parametrization has the advantage of preserving proper analytic structure of the Jost matrix and can be done not only near the threshold energies, but around any collision or even complex energy. As soon as the parameters are obtained, the Jost matrix (and therefore the S-matrix) is known analytically on all sheets of the Riemann surface, and thus enables one to locate possible resonances.

Rakityansky, S. A. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa)] [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Elander, N. [Division of Chemical Physics, Department of Physics, Stockholm University, Stockholm, SE-106 91 (Sweden)] [Division of Chemical Physics, Department of Physics, Stockholm University, Stockholm, SE-106 91 (Sweden)

2013-12-15

94

Analytic structure of the multichannel Jost matrix for potentials with Coulombic tails

NASA Astrophysics Data System (ADS)

A quantum system is considered that can move in N two-body channels with the potentials that may include the Coulomb interaction. For this system, the Jost matrix is constructed in such a way that all its dependencies on the channel momenta and Sommerfeld parameters are factorized in the form of explicit analytic expressions. It is shown that the two remaining unknown matrices are single-valued analytic functions of the energy and therefore can be expanded in the Taylor series near an arbitrary point within the domain of their analyticity. It is derived a system of first-order differential equations whose solutions determine the expansion coefficients of these series. Alternatively, the unknown expansion coefficients can be used as fitting parameters for parametrizing experimental data similarly to the effective-range expansion. Such a parametrization has the advantage of preserving proper analytic structure of the Jost matrix and can be done not only near the threshold energies, but around any collision or even complex energy. As soon as the parameters are obtained, the Jost matrix (and therefore the S-matrix) is known analytically on all sheets of the Riemann surface, and thus enables one to locate possible resonances.

Rakityansky, S. A.; Elander, N.

2013-12-01

95

Diffraction at a time grating in above-threshold ionization: The influence of the Coulomb potential

We analyze the photoelectron emission spectrum in atomic above-threshold ionization by a linearly polarized short-laser pulse. Direct electrons can be characterized by both intracycle and intercycle interferences. The former results from the coherent superposition of two different electron trajectories released in the same optical cycle, whereas the latter is the consequence of the superposition of multiple trajectories released in different cycles. In the present article, a semiclassical analytical expression for the complete (both intracycle and intercycle) interference pattern is derived. We show that the recently proposed semiclassical description in terms of a diffraction process at a time grating remains qualitatively unchanged in the presence of the long-range Coulomb potential. The latter causes only a phase shift of the intracycle interference pattern. We verify the predictions of the semiclassical model by comparison with full three-dimensional (3D) time-dependent Schroedinger equation (TDSE) solutions. One key finding is that the subcycle interference structures originating from trajectories launched within a time interval of less than 1 femtosecond should be experimentally observable also in low-resolution spectra for longer multicycle pulses.

Arbo, Diego G. [Institute for Astronomy and Space Physics, IAFE (CONICET-UBA), CC 67, Suc. 28 (1428) Buenos Aires (Argentina); Department of Physics, FCEN, University of Buenos Aires (Argentina); Ishikawa, Kenichi L. [Photon Science Center, Graduate School of Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan); Schiessl, Klaus; Persson, Emil; Burgdoerfer, Joachim [Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/136, A-1040 Vienna (Austria)

2010-10-15

96

Electron in the Aharonov-Bohm potential and in the Coulomb field in 2+1 dimensions

NASA Astrophysics Data System (ADS)

We obtain exact solutions of the Dirac equation in 2+1 dimensions and the electron energy spectrum in the superposition of the Aharonov-Bohm and Coulomb potentials, which are used to study the Aharonov-Bohm effect for states with continuous and discrete energy spectra. We represent the total scattering amplitude as the sum of amplitudes of scattering by the Aharonov-Bohm and Coulomb potentials. We show that the gauge-invariant phase of the wave function or the energy of the electron bound state can be observed. We obtain a formula for the scattering cross section of spin-polarized electrons scattered by the Aharonov-Bohm potential. We discuss the problem of the appearance of a bound state if the interaction between the electron spin and the magnetic field is taken into account in the form of the two-dimensional Dirac delta function.

Khalilov, V. R.

2006-12-01

97

Spontaneous fermion creation in the coulomb field and Aharonov-Bohm potential in 2+1 dimensions

NASA Astrophysics Data System (ADS)

We find exact solutions of the Dirac equation and the fermion energy spectrum in the Coulomb ( vector and scalar) potential and Aharonov-Bohm potential in 2+1 dimensions taking the particle spin into account. We describe the fermion spin using the two-component Dirac equation with the additional ( spin) parameter introduced by Hagen. We consider the effect of creation of fermion pairs from the vacuum by a strong Coulomb field in the Aharonov-Bohm potential in 2+1 dimensions. We obtain transcendental equations implicitly determining the electron energy spectrum near the boundary of the lower energy continuum and the critical charge. We numerically solve the equation for the critical charge. We show that for relatively weak magnetic flows, the critical charge decreases ( compared with the case with no magnetic field) if the energy of interaction of the electron spin magnetic moment with the magnetic field is negative and increases if this energy is positive.

Khalilov, V. R.

2009-02-01

98

Numerical study of a binary Yukawa model in regimes characteristic of globular proteins in solutions

The main goal of this paper is to assess the limits of validity, in the regime of low concentration and strong Coulomb coupling (high molecular charges), of a simple perturbative approximation to the radial distribution functions (RDF's), based upon a low-density expansion of the potential of mean force and proposed to describe protein-protein interactions in a recent small-angle-scattering (SAS) experimental study. A highly simplified Yukawa (screened Coulomb) model of monomers and dimers of a charged globular protein ({beta}-lactoglobulin) in solution is considered. We test the accuracy of the RDF approximation, as a necessary complementary part of the previous experimental investigation, by comparison with the fluid structure predicted by approximate integral equations and exact Monte Carlo (MC) simulations. In the MC calculations, an Ewald construction for Yukawa potentials has been used to take into account the long-range part of the interactions in the weakly screened cases. Our results confirm that the perturbative first-order approximation is valid for this system even at strong Coulomb coupling, provided that the screening is not too weak (i.e., for Debye length smaller than monomer radius). A comparison of the MC results with integral equation calculations shows that both the hypernetted-chain (HNC) and Percus-Yevick closures have a satisfactory behavior under these regimes, with the HNC being superior throughout. The relevance of our findings for interpreting SAS results is also discussed.

Giacometti, Achille; Gazzillo, Domenico; Pastore, Giorgio; Das, Tushar Kanti [Istituto Nazionale per la Fisica della Materia and Dipartimento di Chimica Fisica, Universita di Venezia, S. Marta DD 2137, I-30123 Venice (Italy); Dipartimento di Fisica Teorica, Universita di Trieste and INFM-DEMOCRITOS, National Simulation Center, Strada Costiera 11, Miramare, I-34100 Trieste (Italy); ICTP, Diploma Course, Strada Costiera 11, Miramare P.O Box 586, I-34100 Trieste (Italy)

2005-03-01

99

Dimensional phase transition in small Yukawa clusters.

We investigate the one- to two-dimensional zigzag transition in clusters consisting of a small number of particles interacting through a Yukawa (Debye) potential and confined in a two-dimensional biharmonic potential well. Dusty (complex) plasma clusters with n

Sheridan, T E; Wells, K D

2010-01-01

100

Dimensional phase transition in small Yukawa clusters

NASA Astrophysics Data System (ADS)

We investigate the one- to two-dimensional zigzag transition in clusters consisting of a small number of particles interacting through a Yukawa (Debye) potential and confined in a two-dimensional biharmonic potential well. Dusty (complex) plasma clusters with n?19 monodisperse particles are characterized experimentally for two different confining wells. The well anisotropy is accurately measured, and the Debye shielding parameter is determined from the longitudinal breathing frequency. Debye shielding is shown to be important. A model for this system is used to predict equilibrium particle configurations. The experiment and model exhibit excellent agreement. The critical value of n for the zigzag transition is found to be less than that predicted for an unshielded Coulomb interaction. The zigzag transition is shown to behave as a continuous phase transition from a one-dimensional to a two-dimensional state, where the state variables are the number of particles, the well anisotropy and the Debye shielding parameter. A universal critical exponent for the zigzag transition is identified for transitions caused by varying the Debye shielding parameter.

Sheridan, T. E.; Wells, K. D.

2010-01-01

101

NASA Astrophysics Data System (ADS)

We model the effect of gravitational settling in the upper chromosphere on O, Fe, Si, and Ne, studying whether Coulomb collisions between ionized low First Ionization Potential (FIP) elements and protons is sufficient to cause abundance enhancements relative to oxygen. We find that low-FIP abundance enhancements comparable to observed values can be obtained provided the hydrogen ionization degree lies in the approximate range 10%-30%, which agrees with chromospheric models. Lower or higher hydrogen ionization causes the FIP-effect to become smaller or absent (depletion of all heavy elements). Iron must be almost fully ionized in order to become enriched relative to high-FIP elements, and this requires a high iron photoionization rate. The time scale necessary to produce the enrichment increases rapidly with increasing H ionization. For iron in a background from a semiempirical chromospheric model, with an H ion fraction of the order of 30%-40% in the upper chromosphere, 1-2 hr of settling is required to produce enhancements comparable to observations. The absolute abundance (relative to H), which monotonically decreases with time during settling, has by that time decreased by less than 50% in the same altitude region. With the same background conditions, the silicon abundance is more strongly enhanced by the settling than the iron abundance. The high-FIP element neon is depleted, relative to O and low-FIP elements, in the same background and altitude region where iron is enhanced, typically by 50% or more relative to O after 1-2 hr of settling.

Bø, Iselin M. Th.; Esser, Ruth; Lie-Svendsen, Øystein

2013-05-01

102

We prove that a relativistic Coulomb excitation calculation in which the classical electromagnetic field of the projectile is used to induce transitions between target states gives the same target transition amplitudes, to all orders of perturbation theory, as would a calculation in which the interaction between projectile and target is mediated by a quantized electromagnetic field.

B. F. Bayman; F. Zardi

2005-01-11

103

We discuss the arising of bound states solutions of the Schrödinger equation due to the presence of a Coulomb-type potential induced by the interaction between a moving electric quadrupole moment and a magnetic field. Furthermore, 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, whose meaning is that not all values of the angular frequency are allowed. -- Highlights: • Interaction between a moving electric quadrupole moment and a magnetic field. • Arising of bound states solutions due to the presence of a Coulomb-type potential. • Influence of the Coulomb-type potential on the harmonic oscillator. • Dependence of the angular frequency on the quantum numbers of the system.

Bakke, K., E-mail: kbakke@fisica.ufpb.br

2014-02-15

104

NASA Astrophysics Data System (ADS)

Approximate analytical solutions of the Dirac equation for Tietz—Hua (TH) potential including Coulomb-like tensor (CLT) potential with arbitrary spin—orbit quantum number ? are obtained within the Pekeris approximation scheme to deal with the spin—orbit coupling terms ?(? ± 1)r-2. Under the exact spin and pseudospin symmetric limitation, bound state energy eigenvalues and associated unnormalized two-component wave functions of the Dirac particle in the field of both attractive and repulsive TH potential with tensor potential are found using the parametric Nikiforov—Uvarov (NU) method. The cases of the Morse oscillator with tensor potential, the generalized Morse oscillator with tensor potential, and the non-relativistic limits have been investigated.

Sameer, M. Ikhdair; Majid, Hamzavi

2013-09-01

105

NASA Astrophysics Data System (ADS)

The mean inner Coulomb potential (MIP) of ZnS, CdS, ZnSe, CdSe, ZnTe, and CdTe has been calculated for a (110) slab geometry by the full potential linearized augmented plane-wave (FLAPW) method using both the local density approximation (LDA) and a generalized gradient approximation (GGA) for the exchange and correlation part of the potential. Typical differences between values calculated within the LDA and the GGA are smaller than typical experimental error bars in literature. We use experimental and self-consistently calculated lattice parameters for the calculation of the MIP. Values calculated for ZnS are compared with experimental values.

Schowalter, M.; Lamoen, D.; Rosenauer, A.; Kruse, P.; Gerthsen, D.

2004-11-01

106

Stimulated two-photon free-free transitions in a Coulomb potential: Formalism

We present a calculation of the cross sections for two-photon free-free transitions of an electron colliding with a Coulomb center of force. The calculation is based on second-order perturbation theory, in the nonrelativistic dipole approximation. The matrix elements for absorption and emission were integrated analytically in momentum space, following a method developed earlier by one of us. This makes use of the Schwinger integral representation for the Coulomb Green's function. The result was expressed in terms of integrals over hypergeometric functions of the Gauss type. Simple limiting forms of these complicated expressions were found in the first Born approximation, and at low and high photon energies. The results derived agree with those obtained by direct calculations done for these limits. Finally, concluding remarks on the analytic part of our work are made. The numerical computation of the two-photon free-free transition cross sections for absorption and emission in various geometries is planned to be presented at a later time.

Gavrila, M. (FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098SJ Amsterdam (The Netherlands)); Maquet, A.; Veniard, V. (Laboratoire de Chimie Physique, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, F-75231 Paris CEDEX 05 (France))

1990-07-01

107

Energy eigenvalues of spherical symmetric potentials with relativistic corrections: analytic results

NASA Astrophysics Data System (ADS)

Based on the investigation of the asymptotic behaviour of the polarization loop function for charged n scalar particles in an external gauge field, we determine the interaction Hamiltonian including the relativistic corrections. The energy eigenvalues of spherical symmetric potentials for two-particle bound state systems with relativistic corrections are analytically derived. The energy spectra of linear and funnel potentials with orbital and radial excitations are determined. The energy spectrum of a superposition of Coulomb and Yukawa potentials is also determined. Our result shows that the energy spectrum with the relativistic corrections for the linear, harmonic oscillator and funnel potentials is smaller than the upper boundaries for the energy spectrum established in the framework of the spinless Salpeter equation for the orbital and radial excited states. The relativistic corrections to the energy spectrum of a superposition of the attractive Coulomb potential and the Yukawa (exponentially screened Coulomb) potentials are very small.

Dineykhan, M.; Zhaugasheva, S. A.; Toinbaeva, N. Sh

2010-01-01

108

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

109

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

110

Stable centred tetragonal phases in the hard core Yukawa system.

The hard core Yukawa system, consisting of particles with an impenetrable core and interacting via a repulsive Yukawa pair potential, is known to solidify either in a bcc or fcc crystal. Using optimization strategies based on genetic algorithms we give evidence that at zero temperature an additional centred tetragonal phase structure in the range of high packing fractions emerges. PMID:21832481

Pauschenwein, Gernot J; Kahl, Gerhard

2009-11-25

111

Stable centred tetragonal phases in the hard core Yukawa system

NASA Astrophysics Data System (ADS)

The hard core Yukawa system, consisting of particles with an impenetrable core and interacting via a repulsive Yukawa pair potential, is known to solidify either in a bcc or fcc crystal. Using optimization strategies based on genetic algorithms we give evidence that at zero temperature an additional centred tetragonal phase structure in the range of high packing fractions emerges.

Pauschenwein, Gernot J.; Kahl, Gerhard

2009-11-01

112

The supersymmetric solutions of PT-symmetric and Hermitian/non-Hermitian forms of quantum systems are obtained by solving the Schrodinger equation for the Exponential-Cosine Screened Coulomb potential. The Hamiltonian hierarchy inspired variational method is used to obtain the approximate energy eigenvalues and corresponding wave functions.

Gholamreza Faridfathi; Ramazan Sever

2006-02-23

113

Yukawa coupling in three dimensions. II

NASA Astrophysics Data System (ADS)

The effective potential for the simplest Yukawa model in 2+1 dimensions discussed in a previous paper is computed to two-loop order. The radiative corrections serve to destabilize the vacuum, both when the fermion is a Dirac spinor and when it is a Majorana spinor but with the instability occurring at values of the external field where perturbation theory is unreliable. If the Yukawa coupling and the self-coupling of the scalar are related by supersymmetry, stability is present. Renormalization of the supersymmetric version of this model presents special difficulties when the auxiliary field is not eliminated using the field equations. In an appendix, the renormalization group functions for a three dimensional Euclidean space model with two Yukawa couplings is analyzed, showing that one of the two couplings is asymptotically free.

McKeon, D. G. C.; Nguyen, K.

1999-10-01

114

The problem of analytical solutions of the 3-dimensional Dirac equation is usually studied via techniques such as The Nikiforov-Uvarov (NU) method. Here, we see that one of the most attractive potentials can be brought into a well-known form of Schroedinger-like problem possessing known solutions via the methodology of supersymmetry (SUSY). Next, using the idea of shape invariance, we calculate exact solutions of Dirac equation for quadratic scalar and vector potentials in the presence of a tensor potential that depends on the radial component either linearly or inversely. The tensor potential itself, besides its applications, removes degeneracy, too.

Zarrinkamar, S., E-mail: zarrinkamar.s@gmail.co [Physics Department, Shahrood University of Technology, P.O. Box 3619995161-316, Shahrood (Iran, Islamic Republic of); Rajabi, A.A.; Hassanabadi, H. [Physics Department, Shahrood University of Technology, P.O. Box 3619995161-316, Shahrood (Iran, Islamic Republic of)

2010-11-15

115

Metal-insulator transition in doped conjugated polymers: Effects of long-ranged Coulomb potentials

The metal-insulator transition in doped conjugated polymers is investigated for charged impurities that are represented as long-ranged potentials. The impurity positions are randomly selected. The change in the number of electrons is determined by the number of impurities. Physical quantities are derived from a sufficiently large number of samples, each of which is described by a finite-size Su-Schrieffer-Heeger Hamiltonian with

Kikuo Harigaya; Akira Terai

1991-01-01

116

Demonstrating the completeness of wave function solutions of the radial Schroedinger equation is a very difficult task. Existing proofs, relying on operator theory, are often very abstract and far from intuitive comprehension. However, it is possible to obtain rigorous proofs amenable to physical insight, if one restricts the considered class of Schroedinger potentials. One can mention, in particular, unbounded potentials yielding a purely discrete spectrum and short-range potentials. However, those possessing a Coulomb tail, very important for physical applications, have remained problematic due to their long-range character. The method proposed in this paper allows to treat them correctly, provided that the non-Coulomb part of potentials vanishes after a finite radius. Nonlocality of potentials can also be handled. The main idea in the proposed demonstration is that regular solutions behave like sine/cosine functions for large momenta, so that their expansions verify Fourier transform properties. The highly singular point at k=0 of long-range potentials is dealt with properly using analytical properties of Coulomb wave functions. Lebesgue measure theory is avoided, rendering the demonstration clear from a physical point of view.

Michel, N. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Kyoto, 606-8502 (Japan)

2008-02-15

117

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

118

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

2014-04-06

119

ERIC Educational Resources Information Center

Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

Fay, Temple H.

2012-01-01

120

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

121

The Pauli potential V{sub P} in density functional theory is known to be the difference between the functional derivative of the single-particle kinetic energy T{sub s}[n] with respect to the electron density n and its von Weizsaecker counterpart. For the leading Coulombic term in the 1/Z expansion for spherical atomic ions, V{sub P}[n] is written in terms of the kinetic energy density plus n(r) and its low-order derivatives. For comparison, the example of an arbitrary number of closed shells with purely harmonic confinement is also treated.

March, N. H. [Department of Physics, University of Antwerp, Antwerp (Belgium); Oxford University, Oxford (United Kingdom); Nagy, A. [Department of Theoretical Physics, University of Debrecen, H-4010 Debrecen (Hungary)

2010-01-15

122

Theoretical description of spherically confined, strongly correlated Yukawa plasmas.

A theoretical description of the radial density profile for charged particles with Yukawa interaction in a harmonic trap is described. At strong Coulomb coupling shell structure is observed in both computer simulations and experiments. Correlations responsible for such shell structure are described here using a recently developed model based in density functional theory. A wide range of particle number, Coulomb coupling, and screening lengths is considered within the fluid phase. A hypernetted chain approximation shows the formation of shell structure, but fails to give quantitative agreement with Monte Carlo simulation results at strong coupling. Significantly better agreement is obtained within the hypernetted chain structure using a renormalized coupling constant, representing bridge function corrections. PMID:22181283

Bruhn, H; Kählert, H; Ott, T; Bonitz, M; Wrighton, J; Dufty, J W

2011-10-01

123

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

A Yukawa-field approximation of the electrostatic free energy of a molecular solvation system with an implicit or continuum solvent is constructed. It is argued through the analysis of model molecular systems with spherically symmetric geometries that such an approximation is rational. The construction extends non-trivially that of the Coulomb-field approximation which serves as a basis of the widely used generalized Born model of molecular electrostatics. The electrostatic free energy determines the dielectric boundary force that in turn influences crucially the molecular conformation, stability, and dynamics. An explicit formula of such forces with the Yukawa-field approximation is obtained using local coordinates and shape differentiation. PMID:23853423

Cheng, Hsiao-Bing; Cheng, Li-Tien; Li, Bo

2013-01-01

124

Coulomb string tension, asymptotic string tension, and the gluon chain

We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

Greensite, Jeff; Szczepaniak, Adam P.

2015-02-01

125

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

126

On the corresponding states law of the Yukawa fluid.

We have analyzed the currently available simulation results as well as performed some additional Monte Carlo simulation for the hard-core attractive Yukawa fluid in order to study its corresponding state behavior. We show that the values of reduced surface tension map onto the master curve and a universal equation of state can be obtained in the wide range of the attractive Yukawa tail length after a certain rescaling of the number density. Some comparisons with other nonconformal potentials are presented and discussed. PMID:18397078

Orea, Pedro; Duda, Yurko

2008-04-01

127

Vacuum stability of asymptotically safe gauge-Yukawa theories

We study the phase diagram and the stability of the ground state for certain four-dimensional gauge-Yukawa theories whose high-energy behaviour is controlled by an interacting fixed point. We also provide analytical and numerical results for running couplings, their crossover scales, the separatrix, and the Coleman-Weinberg effective potential. Classical and quantum stability of the vacuum is established.

Litim, Daniel F; Sannino, Francesco

2015-01-01

128

Coulomb instability of multicharged proteins

NASA Astrophysics Data System (ADS)

We studied the energetics and fragmentation patterns of multicharged (A+)n Morse clusters (n = 55-321), with a total cluster charge Z = n. The Morse pair-potential parameters were characterized by the dissociation energy D = 1-10 eV, range parameter [alpha] = 1-3 Å-1, and interatomic equilibrium separation Re = 1-3 Å. The potential energies [var epsilon] (per particle) of these multicharged Morse clusters at their equilibrium configuration (with bond length r0) were analyzed in terms of the liquid drop model. This resulted in the relation , where the reduced parameters (for the Coulomb energy), (for the interior energy) and (for the surface energy) are independent of the Morse pair-potential parameters. The Rayleigh fissibility parameter X = E(Coulomb)/2E(surface), which determines the fragmentation pattern (i.e., X < 1 for cluster fission and X > 1 for Coulomb explosion), was expressed in the form . The application of this result to the Coulomb instability of multicharged globular proteins reveals that X < 1 for the currently available data. The dominating fragmentation channel is expected to involve spatially anisotropic protein fission into a small number of large fragments, rather than spatially isotropic protein Coulomb explosion into a large number of small fragments.

Jortner, Joshua; Last, Isidore; Levy, Yaacov

2006-03-01

129

Shear viscosity and shear thinning in two-dimensional Yukawa liquids

A two-dimensional Yukawa liquid is studied using two different nonequilibrium molecular dynamics simulation methods. Shear viscosity values in the limit of small shear rates are reported for a wide range of Coulomb coupling parameter and screening length. At high shear rates it is demonstrated that this liquid exhibits shear thinning, i.e., the viscosity $\\eta$ diminishes with increasing shear rate. It is expected that two-dimensional dusty plasmas will exhibit this effect.

Z. Donkó; J. Goree; P. Hartmann; K. Kutasi

2006-03-24

130

Shear Viscosity and Shear Thinning in Two-Dimensional Yukawa Liquids

A two-dimensional Yukawa liquid is studied using two different nonequilibrium molecular dynamics simulation methods. Shear viscosity values in the limit of small shear rates are reported for a wide range of Coulomb coupling parameter and screening lengths. At high shear rates it is demonstrated that this liquid exhibits shear thinning; i.e., the viscosity {eta} diminishes with increasing shear rate. It is expected that two-dimensional dusty plasmas will exhibit this effect.

Donko, Z.; Hartmann, P.; Kutasi, K. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Goree, J. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

2006-04-14

131

The spinless relativistic Yukawa problem

NASA Astrophysics Data System (ADS)

Noticing renewed or increasing interest in the possibility to describe semirelativistic bound states (of either spin-zero constituents or, upon confining oneself to spin-averaged features, constituents with nonzero spin) by means of the spinless Salpeter equation generalizing the Schrödinger equation toward incorporation of effects caused by relativistic kinematics, we revisit this problem for interactions between bound-state constituents of Yukawa shape, by recalling and applying several well-known tools enabling to constrain the resulting spectra.

Lucha, Wolfgang; Schöberl, Franz F.

2014-12-01

132

NASA Astrophysics Data System (ADS)

The traditional photon absorbers Cu2-xX (X = S, Se, and Te) have regained significant research attention in the search of earth-abundant photovoltaic materials. These moderate- and narrow-gap materials have also been shown to exhibit excellent thermoelectric properties recently. However, semimetallic band structures with inverted band orderings are predicted for antifluorite structure Cu2X using density functional theory with the local density approximation or the generalized gradient approximation. We find that semiconducting band structures and normal band orderings can be obtained using the modified Becke-Johnson potential plus an on-site Coulomb U (the mBJ+U approach), which is consistent with our earlier finding for diamond-like Cu-based multinary semiconductors [Y. Zhang, J. Zhang, W. Gao, T. A. Abtew, Y. Wang, P. Zhang, and W. Zhang, J. Chem. Phys. 139, 184706 (2013)]. The trend of the chemical bonding of Cu2X is analyzed, which shows that the positions of the valence band maximum and conduction band minimum are strongly affected by the inter-site pd and intra-site sp hybridizations, respectively. The calculated gaps of Cu2S and Cu2Se still seem to be underestimated compared with experimental results. We also discuss the effects of different structural phases and Cu disordering and deficiency on the bandgaps of these materials.

Zhang, Yubo; Wang, Youwei; Xi, Lili; Qiu, Ruihao; Shi, Xun; Zhang, Peihong; Zhang, Wenqing

2014-02-01

133

The traditional photon absorbers Cu{sub 2?x}X (X = S, Se, and Te) have regained significant research attention in the search of earth-abundant photovoltaic materials. These moderate- and narrow-gap materials have also been shown to exhibit excellent thermoelectric properties recently. However, semimetallic band structures with inverted band orderings are predicted for antifluorite structure Cu{sub 2}X using density functional theory with the local density approximation or the generalized gradient approximation. We find that semiconducting band structures and normal band orderings can be obtained using the modified Becke-Johnson potential plus an on-site Coulomb U (the mBJ+U approach), which is consistent with our earlier finding for diamond-like Cu-based multinary semiconductors [Y. Zhang, J. Zhang, W. Gao, T. A. Abtew, Y. Wang, P. Zhang, and W. Zhang, J. Chem. Phys. 139, 184706 (2013)]. The trend of the chemical bonding of Cu{sub 2}X is analyzed, which shows that the positions of the valence band maximum and conduction band minimum are strongly affected by the inter-site pd and intra-site sp hybridizations, respectively. The calculated gaps of Cu{sub 2}S and Cu{sub 2}Se still seem to be underestimated compared with experimental results. We also discuss the effects of different structural phases and Cu disordering and deficiency on the bandgaps of these materials.

Zhang, Yubo; Wang, Youwei; Xi, Lili; Qiu, Ruihao; Shi, Xun [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)] [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Peihong, E-mail: wqzhang@mail.sic.ac.cn, E-mail: pzhang3@buffalo.edu [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States) [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States); Beijing Computational Science Research Center, Beijing 100084 (China); Zhang, Wenqing, E-mail: wqzhang@mail.sic.ac.cn, E-mail: pzhang3@buffalo.edu [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China) [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); School of Chemistry and Chemical Engineering, and Sate Key Laboratory of Coordination Chemistry, Nanjing University, Jiangsu 210093 (China)

2014-02-21

134

Properties and computation of the Coulomb pair density matrix

NASA Astrophysics Data System (ADS)

The Coulomb pair density matrix is essential in numerical quantum mechanical studies of Coulombic systems. The properties of the pair density matrix in two and three dimensions for attractive and repulsive coulomb potentials are discussed here. These are incorporated into several listed fortran subroutines.

Pollock, E. L.

1988-12-01

135

Entropic Corrections to Coulomb's Law

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

S. H. Hendi; A. Sheykhi

2011-10-17

136

Power law behavior of the zigzag transition in Yukawa clusters

NASA Astrophysics Data System (ADS)

We provide direct experimental evidence that the width of a Yukawa cluster exhibits power law behavior during the one-dimensional (1D) to two-dimensional (2D) zigzag transition. Configurations of small dusty (complex) plasma clusters confined in a biharmonic potential well are characterized as the well anisotropy is varied. When the anisotropy is large the particles are in a 1D straight-line configuration. As the anisotropy is decreased the cluster undergoes a zigzag transition to a 2D configuration. The measured dependence of cluster width on anisotropy follows a power law. A second transition from the zigzag to an elliptical configuration is also observed. The results are in very good agreement with a model of identical particles interacting through a Yukawa potential.

Sheridan, T. E.; Magyar, Andrew L.

2010-11-01

137

We show that finite-range alternatives to the standard long-range pair potential for silica by van Beest et al. [Phys. Rev. Lett. 64, 1955 (1990)] might be used in molecular dynamics simulations. We study two such models that can be efficiently simulated since no Ewald summation is required. We first consider the Wolf method, where the Coulomb interactions are truncated at a cutoff distance rc such that the requirement of charge neutrality holds. Various static and dynamic quantities are computed and compared to results from simulations using Ewald summations. We find very good agreement for rc approximately 10 A. For lower values of rc, the long-range structure is affected which is accompanied by a slight acceleration of dynamic properties. In a second approach, the Coulomb interaction is replaced by an effective Yukawa interaction with two new parameters determined by a force fitting procedure. The same trend as for the Wolf method is seen. However, slightly larger cutoffs have to be used in order to obtain the same accuracy with respect to static and dynamic quantities as for the Wolf method. PMID:17887862

Carré, Antoine; Berthier, Ludovic; Horbach, Jürgen; Ispas, Simona; Kob, Walter

2007-09-21

138

The structure of spherical clusters composed of Yukawa particles is analyzed by molecular dynamics simulations and theoretical approaches as a model for dust particles in dusty plasmas in the isotropic environment. The latter condition is expected to be realized under microgravity or by active cancellation of the effect of gravity on the ground. It is found that, at low temperatures, Yukawa particles form spherical shells and, when scaled by the mean distance, the structure is almost independent of the strength of screening including the case of the Coulomb interaction. The positions and populations of shells and the conditions for the change of the number of shells are expressed by simple interpolation formulas. Shells have an approximately equal spacing close to that of triangular lattice planes in the bulk close-packed structures. It is shown that, when the cohesive energy in each shell is properly taken into account, the shell model reproduces the structure of spherical Yukawa clusters to a good accuracy.

Totsuji, Hiroo; Ogawa, Takafumi; Totsuji, Chieko; Tsuruta, Kenji [Graduate School of Science and Technology and Faculty of Engineering, Okayama University, Tsushimanaka 3-1-1, Okayama 700-8530 (Japan)

2005-09-01

139

Coulomb-modified nuclear scattering. II

NASA Astrophysics Data System (ADS)

Exact analytical expressions for the off-shell Jost function fl(k, q) for the Coulomb and Coulomb-distorted nuclear potentials are constructed in terms of the sum of Gaussian hypergeometric functions by using an integral representation for fl(k, q) given by Fuda. It is pointed out that the hypergeometric functions which occur here can be generated by the use of a well-known three-term recurrence relation. With van Haeringen our expressions for fl(k, q) exhibit discontinuity in the on-shell limit q?k. This discontinuous behavior has been attributed to the long range nature of the Coulomb force.

Talukdar, B.; Saha, S.; Sasakawa, T.

1983-03-01

140

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

141

Transverse current fluctuations in the Yukawa one-component plasma.

Using numerical simulations, we investigate the wave number and frequency dependent transverse current correlation function CT(k,?) of a single-component fluid with Yukawa interaction potential, also known as the Yukawa one-component plasma. The transverse current correlation function is an important quantity because it contains the microscopic details of the viscoelastic behavior of the fluid. We show that, in the region of densities and temperatures in which shear waves do not propagate, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. As either the density is increased or the temperature decreased, the transverse current correlation function shows additional structure that the simple models fail to capture. PMID:24580340

Mithen, James P

2014-01-01

142

Transverse current fluctuations in the Yukawa one-component plasma

NASA Astrophysics Data System (ADS)

Using numerical simulations, we investigate the wave number and frequency dependent transverse current correlation function CT(k,?) of a single-component fluid with Yukawa interaction potential, also known as the Yukawa one-component plasma. The transverse current correlation function is an important quantity because it contains the microscopic details of the viscoelastic behavior of the fluid. We show that, in the region of densities and temperatures in which shear waves do not propagate, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. As either the density is increased or the temperature decreased, the transverse current correlation function shows additional structure that the simple models fail to capture.

Mithen, James P.

2014-01-01

143

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

144

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

145

Diffusion in Coulomb crystals.

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 ?=175 to Coulomb parameters up to ?=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. PMID:21867316

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

2011-07-01

146

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

147

Minimal SUSY SO(10) and Yukawa unification

The minimal supersymmetric (SUSY) SO(10) model, where only two Higgs multiplets {l_brace}10 Circled-Plus 126-bar{r_brace} are utilized for Yukawa couplings with matter fields, can nicely fit the neutrino oscillation parameters as well as charged fermion masses and mixing angles. In the fitting of the fermion mass matrix data, the largest element in the Yukawa coupling with the 126-bar -plet Higgs (Y{sup 126}) is found to be of order one, so that the right see-saw scale should be provided by Higgs vacuum expectation values (VEVs) of {beta}(10{sup 14}GeV). This fact causes a serious problem, namely, the gauge coupling unification is spoiled because of the presence of many exotic Higgs multiples emerging at the see-saw scale. In order to solve this problem, we consider a unification between bottom-quark and tau Yukawa couplings (b - {tau} Yukawa coupling unification) at the grand unified theory (GUT) scale, due to threshold corrections of superpartners to the Yukawa couplings at the 1 TeV scale. When the b - {tau} Yukawa coupling unification is very accurate, the largest element in Y{sub 126} can become {beta}(0.01), so that the right see-saw scale is realized by the GUT scale VEV and the usual gauge coupling unification is maintained. Since the b - {tau} Yukawa unification alters the Yukawa coupling data at the GUT scale, we re-analyze the fitting of the fermion mass matrix data by taking all the relevant free parameters into account. Unfortunately, we find that no parameter region shows up to give a nice fit for the current neutrino oscillation data and therefore, the usual picture of the gauge coupling unification cannot accommodate the fermion mass matrix data fitting in our procedure.

Okada, Nobuchika [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487 (United States)

2013-05-23

148

Minimal SUSY SO(10) and Yukawa unification

NASA Astrophysics Data System (ADS)

The minimal supersymmetric (SUSY) SO(10) model, where only two Higgs multiplets {10 ? 126} are utilized for Yukawa couplings with matter fields, can nicely fit the neutrino oscillation parameters as well as charged fermion masses and mixing angles. In the fitting of the fermion mass matrix data, the largest element in the Yukawa coupling with the 126-plet Higgs (Y126) is found to be of order one, so that the right see-saw scale should be provided by Higgs vacuum expectation values (VEVs) of \\Vbgr(1014GeV). This fact causes a serious problem, namely, the gauge coupling unification is spoiled because of the presence of many exotic Higgs multiples emerging at the see-saw scale. In order to solve this problem, we consider a unification between bottom-quark and tau Yukawa couplings (b - ? Yukawa coupling unification) at the grand unified theory (GUT) scale, due to threshold corrections of superpartners to the Yukawa couplings at the 1 TeV scale. When the b - ? Yukawa coupling unification is very accurate, the largest element in Y126 can become \\Vbgr(0.01), so that the right see-saw scale is realized by the GUT scale VEV and the usual gauge coupling unification is maintained. Since the b - ? Yukawa unification alters the Yukawa coupling data at the GUT scale, we re-analyze the fitting of the fermion mass matrix data by taking all the relevant free parameters into account. Unfortunately, we find that no parameter region shows up to give a nice fit for the current neutrino oscillation data and therefore, the usual picture of the gauge coupling unification cannot accommodate the fermion mass matrix data fitting in our procedure.

Okada, Nobuchika

2013-05-01

149

Indirect handle on the down-quark yukawa coupling.

To measure the Yukawa couplings of the up and down quarks, Y_{u,d}, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a change of more than 50% in Y_{d} would generically result in ds transitions in conflict with kaon physics. This could already be seen as evidence for a nonvanishing direct coupling of the down quark to the newly discovered Higgs boson. The nonobservation of certain-already well-constrained-processes is thus turned into a powerful indirect measure of otherwise basically unaccessible physical parameters of the effective standard model. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on Y_{u}. PMID:25615309

Goertz, Florian

2014-12-31

150

Indirect Handle on the Down-Quark Yukawa Coupling

NASA Astrophysics Data System (ADS)

To measure the Yukawa couplings of the up and down quarks, Yu ,d, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a change of more than 50% in Yd would generically result in d s transitions in conflict with kaon physics. This could already be seen as evidence for a nonvanishing direct coupling of the down quark to the newly discovered Higgs boson. The nonobservation of certain—already well-constrained—processes is thus turned into a powerful indirect measure of otherwise basically unaccessible physical parameters of the effective standard model. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on Yu.

Goertz, Florian

2014-12-01

151

Bcc crystal-fluid interfacial free energy in Yukawa systems

NASA Astrophysics Data System (ADS)

We determine the orientation-resolved interfacial free energy between a body-centered-cubic (bcc) crystal and the coexisting fluid for a many-particle system interacting via a Yukawa pair potential. For two different screening strengths, we compare results from molecular dynamics computer simulations, density functional theory, and a phase-field-crystal approach. Simulations predict an almost orientationally isotropic interfacial free energy of 0.12kBT/a2 (with kBT denoting the thermal energy and a the mean interparticle spacing), which is independent of the screening strength. This value is in reasonable agreement with our Ramakrishnan-Yussouff density functional calculations, while a high-order fitted phase-field-crystal approach gives about 2-3 times higher interfacial free energies for the Yukawa system. Both field theory approaches also give a considerable anisotropy of the interfacial free energy. Our result implies that, in the Yukawa system, bcc crystal-fluid free energies are a factor of about 3 smaller than face-centered-cubic crystal-fluid free energies.

Heinonen, V.; Mijailovi?, A.; Achim, C. V.; Ala-Nissila, T.; Rozas, R. E.; Horbach, J.; Löwen, H.

2013-01-01

152

Phase behavior of the modified-Yukawa fluid and its sticky limit

NASA Astrophysics Data System (ADS)

Simple model systems with short-range attractive potentials have turned out to play a crucial role in determining theoretically the phase behavior of proteins or colloids. However, as pointed out by D. Gazzillo [J. Chem. Phys. 134, 124504 (2011)], one of these widely used model potentials, namely, the attractive hard-core Yukawa potential, shows an unphysical behavior when one approaches its sticky limit, since the second virial coefficient is diverging. However, it is exactly this second virial coefficient that is typically used to depict the experimental phase diagram for a large variety of complex fluids and that, in addition, plays an important role in the Noro-Frenkel scaling law [J. Chem. Phys. 113, 2941 (2000)], which is thus not applicable to the Yukawa fluid. To overcome this deficiency of the attractive Yukawa potential, D. Gazzillo has proposed the so-called modified hard-core attractive Yukawa fluid, which allows one to correctly obtain the second and third virial coefficients of adhesive hard-spheres starting from a system with an attractive logarithmic Yukawa-like interaction. In this work we present liquid-vapor coexistence curves for this system and investigate its behavior close to the sticky limit. Results have been obtained with the self-consistent Ornstein-Zernike approximation (SCOZA) for values of the reduced inverse screening length parameter up to 18. The accuracy of SCOZA has been assessed by comparison with Monte Carlo simulations.

Schöll-Paschinger, Elisabeth; Valadez-Pérez, Néstor E.; Benavides, Ana L.; Castañeda-Priego, Ramón

2013-11-01

153

Phase behavior of the modified-Yukawa fluid and its sticky limit.

Simple model systems with short-range attractive potentials have turned out to play a crucial role in determining theoretically the phase behavior of proteins or colloids. However, as pointed out by D. Gazzillo [J. Chem. Phys. 134, 124504 (2011)], one of these widely used model potentials, namely, the attractive hard-core Yukawa potential, shows an unphysical behavior when one approaches its sticky limit, since the second virial coefficient is diverging. However, it is exactly this second virial coefficient that is typically used to depict the experimental phase diagram for a large variety of complex fluids and that, in addition, plays an important role in the Noro-Frenkel scaling law [J. Chem. Phys. 113, 2941 (2000)], which is thus not applicable to the Yukawa fluid. To overcome this deficiency of the attractive Yukawa potential, D. Gazzillo has proposed the so-called modified hard-core attractive Yukawa fluid, which allows one to correctly obtain the second and third virial coefficients of adhesive hard-spheres starting from a system with an attractive logarithmic Yukawa-like interaction. In this work we present liquid-vapor coexistence curves for this system and investigate its behavior close to the sticky limit. Results have been obtained with the self-consistent Ornstein-Zernike approximation (SCOZA) for values of the reduced inverse screening length parameter up to 18. The accuracy of SCOZA has been assessed by comparison with Monte Carlo simulations. PMID:24320299

Schöll-Paschinger, Elisabeth; Valadez-Pérez, Néstor E; Benavides, Ana L; Castañeda-Priego, Ramón

2013-11-14

154

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

155

We consider various configurations of T-branes which are non-abelian bound states of branes and were recently introduced by Cecotti, Cordova, Heckman and Vafa. They are a refinement of the concept of monodromic branes featured in phenomenological F-theory models. We are particularly interested in the T-branes corresponding to Z3 and Z4 monodromies, which are used to break E7 or E8 gauge groups to SU(5) GUT. Our results imply that the up-type and down-type Yukawa couplings for the breaking of E7 are zero, whereas up-type and down-type Yukawa couplings, together with right handed neutrino Yukawas are non-zero for the case of the breaking of E8. The dimension four proton decay mediating term is avoided in models with either E7 or E8 breaking.

Chan-Chi Chiou; Alon E. Faraggi; Radu Tatar; William Walters

2011-01-12

156

We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective ?{4} Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z<0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z?2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z?0.01, the crossover temperature is the same as for the RPM. PMID:25019760

Patsahan, O

2014-06-01

157

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

158

Electron Radiative Transitions in a Coulomb Field

Free-free, bound-free, and bound-bound Gaunt factors and oscillator ; strengths were computed for electrons in a pure Coulomb potential. Numerical ; results are presented for a wide range of electron and photon energies. In ; addition, for the free-free case, average Gaunt factors and the rate of ; bremsstrahlung production were obtained as functions of temperature for a ; Boltzmann

W. J. Karzas; R. Latter

1961-01-01

159

Solution of the Dirac Equation for a Dirac Particle in a Yukawa Field

The solution of the Dirac equation for a massive spin 1\\/2 particle in a Yukawa-type potential is investigated by transforming the radial form of the Dirac equation into the Whittaker equation from which we have obtained the desired solutions for the regions near the boundaries of the upper and lower energy continuum, E ≈ -\\/+m. Comparison is made with earlier

B. Gulveren; A. Demirtas; R. Ogul

2001-01-01

160

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

161

Coulomb heating behavior of fast light diclusters

In this Brief Report we present data on the Coulomb heating induced by B{sub 2}{sup +} molecular beams channeling along Si<100> direction in a large energy interval (800 up to 2200 keV/atom). The simultaneous detection of Si Kalpha x rays and backscattered particles established the necessary grounds for the calculation of the Coulomb heating, i.e., the molecular transversal energy due to the Coulomb explosion transferred to the target atoms. By combining the present results with those previously published for H{sub 2}{sup +} at 150 keV/atom and for C{sub 2}{sup +} at energies from 800 up to 2200 keV/atom, we were able to obtain two striking results. First, all the experimental values fall on a straight line when they are plotted as a function of the stored potential energy per ion, suggesting some kind of 'universal behavior'. Second, the analysis of the whole set of experimental data shows that the Coulomb heating scales with 2/3 of the stored potential energy per ion, regardless the ion atomic number. This result is in agreement with theoretical predictions.

Fadanelli, R. C.; Behar, M.; Dias, J. F. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, CP 15051, CEP 91501-970 Porto Alegre, RS (Brazil)

2010-04-01

162

Yukawa Unification Predictions with effective "Mirage" Mediation

In this letter we analyze the consequences, for the LHC, of gauge and third family Yukawa coupling unification with a particular set of boundary conditions defined at the GUT scale, which we characterize as effective "mirage" mediation. We perform a global chi-squared analysis including the observables M_W, M_Z, G_F, alpha_em, alpha_s(M_Z), M_top, m_b(m_b), M_tau, BR(B -> X_s gamma), BR(B_s -> mu^+ mu^-) and M_{h}. The fit is performed in the MSSM in terms of 10 GUT scale parameters, while tanb and mu are fixed at the weak scale. We find good fits to the low energy data and a SUSY spectrum which is dramatically different than previously studied in the context of Yukawa unification.

Anandakrishnan, Archana

2013-01-01

163

Yukawa Unification Predictions with effective "Mirage" Mediation

In this letter we analyze the consequences, for the LHC, of gauge and third family Yukawa coupling unification with a particular set of boundary conditions defined at the GUT scale, which we characterize as effective "mirage" mediation. We perform a global chi-squared analysis including the observables M_W, M_Z, G_F, alpha_em, alpha_s(M_Z), M_top, m_b(m_b), M_tau, BR(B -> X_s gamma), BR(B_s -> mu^+ mu^-) and M_{h}. The fit is performed in the MSSM in terms of 10 GUT scale parameters, while tanb and mu are fixed at the weak scale. We find good fits to the low energy data and a SUSY spectrum which is dramatically different than previously studied in the context of Yukawa unification.

Archana Anandakrishnan; Stuart Raby

2013-03-20

164

Yukawa unification predictions with effective "mirage" mediation.

In this Letter we analyze the consequences, for the LHC, of gauge and third family Yukawa coupling unification with a particular set of boundary conditions defined at the grand unified theory (GUT) scale, which we characterize as effective "mirage" mediation. We perform a global ?2 analysis including the observables M(W), M(Z), G(F), ?(em)(-1), ?(s)(M(Z)), M(t), m(b)(m(b)), M(?), BR(B?X(s)?), BR(B(s)??(+)?(-)), and M(h). The fit is performed in the minimal supersymmetric standard model in terms of 10 GUT scale parameters, while tan? and ? are fixed at the weak scale. We find good fits to the low energy data and a supersymmetry spectrum which is dramatically different than previously studied in the context of Yukawa unification. PMID:24313477

Anandakrishnan, Archana; Raby, Stuart

2013-11-22

165

Thermal conductivity of strongly coupled Yukawa liquids

NASA Astrophysics Data System (ADS)

The thermal conductivity of strongly coupled Yukawa liquids, being relevant to dusty plasmas, is calculated from nonequilibrium molecular dynamics simulations. The calculations cover a wide range of plasma coupling (?) and screening (?) parameters and yield data which are generally in good agreement with the results of recent independent calculations. An improved analytical formula, relating the thermal conductivity to the reduced temperature and to the screening length, is proposed.

Donkó, Z.; Hartmann, P.

2004-01-01

166

Yukawa unification in SO(10) SUSY GUTs

NASA Astrophysics Data System (ADS)

Supersymmetric grand unified models based on the SO(10) gauge group are especially attractive in light of recent data on neutrino masses. The simplest SO(10) SUSY GUT models predict unification of third generation Yukawa couplings (t - b - tau), in addition to the usual gauge coupling unification. An assessment of the viability of such Yukawa unified models is presented. For the superpotential Higgs mass parameter mu > 0, it is found that unification to less than 1% is possible, but only for GUT scale scalar mass parameter m16 ˜8--20 TeV, and small values of gaugino mass m1/2 ? 150 GeV. Such models require that a GUT scale mass splitting exists amongst Higgs scalars with m2Hu < m2Hd . Viable solutions lead to a radiatively generated inverted scalar mass hierarchy, with third generation and Higgs scalars being lighter than other sfermions. These models have very heavy sfermions, so that unwanted flavor changing and CP violating SUSY processes are suppressed, but may suffer from some fine-tuning requirements. While the generated spectra satisfy b ? sgamma and ( g - 2)mu constraints, there exists tension with the dark matter relic density unless m16 ? 3 TeV. These models offer prospects for a SUSY discovery at the Fermilab Tevatron collider via the search for W1Z2 ˜ ? 3? events, or via gluino pair production. If mu < 0, Yukawa coupling unification to less than 5% can occur for m 16 and m1/2 ? 1 - 2 TeV. Consistency of negative mu Yukawa unified models with b ? sgamma, (g - 2)mu, and relic density Oh2 all imply very large values of m1/2 typically greater than about 2.5 TeV, in which case direct detection of sparticles may be a challenge even at the LHC. To address the tension between Yukawa unification and the excess of dark matter that the mu > 0 models tend to predict, a couple of possible improvements are surveyed. One solution, lowering the GUT scale mass value of first and second generation scalars, leads to uR and c˜R squark masses in the 90 - 120 GeV regime, which should be accessible to Fermilab Tevatron experiments. Another possibility is relaxing gaugino mass universality which may solve the relic density problem by having neutralino annihilations via the Z or h resonances, or by having a wino-like LSP.

Auto, Daniel M.

167

On Coulomb's inverse square law

NASA Astrophysics Data System (ADS)

The famous inverse square law in electrostatics, first published in 1785 by C. A. Coulomb, was strongly contested during the next 40 years, especially in Germany. Therefore, at the Carl von Ossietzky University Oldenburg a replication of the apparatus described by Coulomb was made, and the reasons were investigated why none of his contemporaries succeeded in reproducing his results. In addition the respective theoretical concepts of Coulomb, his supporters, and his opponents were analyzed.

Heering, Peter

1992-11-01

168

Nonlinear compressional waves in a two-dimensional Yukawa lattice.

A modified Korteweg-de Vries (KdV) equation is obtained for studying the propagation of nonlinear compressional waves and pulses in a chain of particles including the effect of damping. Suitably altering the linear phase velocity makes this equation useful also for the problem of phonon propagation in a two-dimensional (2D) lattice. Assuming a Yukawa potential, we use this method to model compressional wave propagation in a 2D plasma crystal, as in a recent experiment. By integrating the modified KdV equation the pulse is allowed to evolve, and good agreement with the experiment is found. It is shown that the speed of a compressional pulse increases with its amplitude, while the speed of a rarefactive pulse decreases. It is further discussed how the drag due to the background gas has a crucial role in weakening nonlinear effects and preventing the emergence of a soliton. PMID:14683049

Avinash, K; Zhu, P; Nosenko, V; Goree, J

2003-10-01

169

Using numerical simulations, we investigate the equilibrium dynamics of a single-component fluid with Yukawa interaction potential. We show that, for a wide range of densities and temperatures, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. Since the Yukawa potential can describe the ion-ion interactions in a plasma, our results have significant applicability for both analyzing and interpreting the results of x-ray scattering data from high-power lasers and fourth-generation light sources. PMID:22181277

Mithen, James P; Daligault, Jérôme; Crowley, Basil J B; Gregori, Gianluca

2011-10-01

170

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

171

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. PMID:25493891

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

2014-11-01

172

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

173

Statics and dynamics of Yukawa cluster crystals on ordered substrates

NASA Astrophysics Data System (ADS)

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.

Reichhardt, C.; Olson Reichhardt, C. J.

2012-05-01

174

Lepton masses and mixing without Yukawa hierarchies

We investigate the neutrino masses and mixing pattern in a version of the SU(3){sub c}(multiply-in-circle sign)SU(3){sub L}(multiply-in-circle sign)U(1){sub X} model with one extra exotic charged lepton per family as introduced by Ozer. It is shown that an extended scalar sector, together with a discrete Z{sub 2} symmetry, is able to reproduce a consistent lepton mass spectrum without a hierarchy in the Yukawa coupling constants, the former as a consequence of a carefull balance between one universal see-saw and two radiative mechanisms.

Ponce, William A.; Zapata, Oscar [Instituto de Fisica, Universidad de Antioquia, Apartado Aereo 1226, Medellin (Colombia)

2006-11-01

175

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

176

Thermodynamics of Thomas-Fermi screened Coulomb systems

NASA Technical Reports Server (NTRS)

We obtain in closed analytic form, estimates for the thermodynamic properties of classical fluids with pair potentials of Yukawa type, with special reference to dense fully ionized plasmas with Thomas-Fermi or Debye-Hueckel screening. We further generalize the hard-sphere perturbative approach used for similarly screened two-component mixtures, and demonstrate phase separation in this simple model of a liquid mixture of metallic helium and hydrogen.

Firey, B.; Ashcroft, N. W.

1977-01-01

177

Diamond-like Cu-based multinary semiconductors are a rich family of materials that hold promise in a wide range of applications. Unfortunately, accurate theoretical understanding of the electronic properties of these materials is hindered by the involvement of Cu d electrons. Density functional theory (DFT) based calculations using the local density approximation or generalized gradient approximation often give qualitative wrong electronic properties of these materials, especially for narrow-gap systems. The modified Becke-Johnson (mBJ) method has been shown to be a promising alternative to more elaborate theory such as the GW approximation for fast materials screening and predictions. However, straightforward applications of the mBJ method to these materials still encounter significant difficulties because of the insufficient treatment of the localized d electrons. We show that combining the promise of mBJ potential and the spirit of the well-established DFT + U method leads to a much improved description of the electronic structures, including the most challenging narrow-gap systems. A survey of the band gaps of about 20 Cu-based semiconductors calculated using the mBJ + U method shows that the results agree with reliable values to within ±0.2 eV.

Zhang, Yubo; Zhang, Jiawei; Wang, Youwei [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)] [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Gao, Weiwei; Abtew, Tesfaye A. [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States)] [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States); Zhang, Peihong, E-mail: pzhang3@buffalo.edu, E-mail: wqzhang@mail.sic.ac.cn [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States) [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States); Beijing Computational Science Research Center, Beijing 100084 (China); Zhang, Wenqing, E-mail: pzhang3@buffalo.edu, E-mail: wqzhang@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China) [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); School of Chemistry and Chemical Engineering and Sate Key Laboratory of Coordination Chemistry, Nanjing University, Jiangsu 210093 (China)

2013-11-14

178

Ionic Coulomb Blockade in Nanopores

Understanding the dynamics of ions in nanopores is essential for applications ranging from single-molecule detection to DNA sequencing. We show both analytically and by means of molecular dynamics simulations that under specific conditions ion-ion interactions in nanopores lead to the phenomenon of ionic Coulomb blockade, namely the build-up of ions inside a nanopore with specific capacitance impeding the flow of additional ions due to Coulomb repulsion. This is the counterpart of electronic Coulomb blockade observed in mesoscopic systems. We discuss the analogies and differences with the electronic case as well as experimental situations in which this phenomenon could be detected. PMID:23307655

Krems, Matt; Di Ventra, Massimiliano

2014-01-01

179

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

180

Ion sphere model for Yukawa systems (dusty plasmas)

NASA Astrophysics Data System (ADS)

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

2014-12-01

181

The LAGEOS satellites orbit and Yukawa-like interactions

NASA Astrophysics Data System (ADS)

LAGEOS II general relativity pericenter precession has been analysed in terms of the errors produced by the mismodelling of both the gravitational and non-gravitational perturbations acting on the satellite orbit. The accuracy in the pericenter determination may be considered as an upper-bound value for the estimate of the strength ? of a possible new-long-range-interaction described by a Yukawa-like potential. In the present work we have focused on the constraints in ? that can be obtained with the current best multi-satellites gravity field model EGM96 (? < 2.6 × 10-10) and also with the first promising models from the CHAMP (? < 1.8 × 10-10) and GRACE (? < 1.2 × 10-10) gravimetric missions. These results represent, potentially, an improvement of two or three orders-of-magnitude with respect to the best constraints obtained in the past with Earth-LAGEOS and Lunar-LAGEOS data (|?| < 10-5-10-8). The impact of the non-gravitational perturbations mismodelling in the final error budget has been determined together with the improvements obtainable in the constraint of the strength ? with the proposed LARES satellite.

Lucchesi, David M.

2011-04-01

182

Cholesteric order in systems of helical Yukawa rods.

We consider the interaction potential between two chiral rod-like colloids which consist of a thin cylindrical backbone decorated with a helical charge distribution on the cylinder surface. For sufficiently slender helical rods a simple scaling expression is derived which relates the chiral 'twisting' potential to the microscopic properties of the particles, such as the internal helical pitch, charge density and electrostatic screening parameter. To predict the behaviour of the macroscopic cholesteric pitch of the fluid bulk phase we invoke a simple second-virial theory generalized to treat anisotropic states with weakly twisted director fields. It is shown that, while particles with weakly coiled helices always form a cholesteric phase whose helical sense is commensurate with that of the internal helix, more strongly coiled rods lead to the formation of a cholesteric state of opposite sense. The correlation between the helical symmetry at the microscopic and macroscopic scale is found to be very sensitive to the pitch of the Yukawa helix. Mixing helical particles of sufficiently disparate length and internal pitch may give rise to a demixing of the uniform cholesteric phase into two fractions with a different macroscopic pitch. Our findings could be relevant to the interpretation of experimental observations in systems of cellulose and chitin microfibres, DNA and fd virus rods. PMID:21525561

Wensink, H H; Jackson, G

2011-05-18

183

Cholesteric order in systems of helical Yukawa rods

NASA Astrophysics Data System (ADS)

We consider the interaction potential between two chiral rod-like colloids which consist of a thin cylindrical backbone decorated with a helical charge distribution on the cylinder surface. For sufficiently slender helical rods a simple scaling expression is derived which relates the chiral 'twisting' potential to the microscopic properties of the particles, such as the internal helical pitch, charge density and electrostatic screening parameter. To predict the behaviour of the macroscopic cholesteric pitch of the fluid bulk phase we invoke a simple second-virial theory generalized to treat anisotropic states with weakly twisted director fields. It is shown that, while particles with weakly coiled helices always form a cholesteric phase whose helical sense is commensurate with that of the internal helix, more strongly coiled rods lead to the formation of a cholesteric state of opposite sense. The correlation between the helical symmetry at the microscopic and macroscopic scale is found to be very sensitive to the pitch of the Yukawa helix. Mixing helical particles of sufficiently disparate length and internal pitch may give rise to a demixing of the uniform cholesteric phase into two fractions with a different macroscopic pitch. Our findings could be relevant to the interpretation of experimental observations in systems of cellulose and chitin microfibres, DNA and fd virus rods.

Wensink, H. H.; Jackson, G.

2011-05-01

184

Kelvin Helmholtz Instability in Strongly Coupled Yukawa Liquids

Using 'first principles' molecular dynamics simulations Kelvin Helmholtz instability has been observed for the first time at the particle level in two-dimensional strongly coupled Yukawa liquids. At a given coupling strength {Gamma} a subsonic shear profile is superposed on an equilibrated Yukawa liquid and instability is observed. Linear growth rates computed directly from MD simulations are seen to increase with strong coupling. Vortex-roll formation in the nonlinear regime is reported.

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

2010-05-28

185

Lorenz or Coulomb in Galilean Electromagnetism ?

Galilean Electromagnetism was discovered thirty years ago by Levy-Leblond & Le Bellac. However, these authors only explored the consequences for the fields and not for the potentials. Following De Montigny & al., we show that the Coulomb gauge condition is the magnetic limit of the Lorenz gauge condition whereas the Lorenz gauge condition applies in the electric limit of L\\'{e}vy-Leblond & Le Bellac. Contrary to De Montigny & al. who used Galilean tensor calculus, we use orders of magnitude based on physical motivations in our derivation.

Germain Rousseaux

2005-02-24

186

Electric field enhanced emission from non-Coulombic traps in semiconductors

Electric field enhancement of emission from three non-Coulombic traps has been calculated: the shielded Coulombic potential, the polarization potential, and the dipole potential. Both the Poole-Frenkel effect and phonon-assisted tunneling have been included, and both were found to be important. The field effect can be used to distinguish between these potentials on the basis of their long range character. This effect is most important in interpreting the results of capacitance transient studies of deep levels.

Martin, P.A.; Streetman, B.G.; Hess, K.

1981-12-01

187

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

188

Supersymmetric Yukawa sum rule and LHC tests

We propose the ''supersymmetric (SUSY) Yukawa sum rule,'' a relationship between physical masses and mixing angles of the third-generation quarks and squarks. The sum rule follows directly from a relation between quark and squark couplings to the Higgs, enforced by SUSY. It is exactly this relation that ensures the cancellation of the one-loop quadratic divergence in the Higgs mass from the top sector. Testing the sum rule experimentally would thus provide a powerful consistency check on SUSY as the solution to the gauge hierarchy problem. While such a test will most likely have to await a future next-generation lepton collider, the LHC experiments may be able to make significant progress towards this goal. If some of the terms entering the sum rule are measured at the LHC, the sum rule can be used (within SUSY framework) to put interesting constraints on the other terms, such as the mixing angles among third-generation squarks. We outline how the required mass measurements could be performed, and estimate the accuracy that can be achieved at the LHC.

Blanke, Monika; Curtin, David; Perelstein, Maxim [Laboratory for Elementary Particle Physics, Cornell University, Ithaca, New York 14850 (United States)

2010-08-01

189

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

190

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

191

Coulomb gauge approach for charmonium meson and hybrid radiative transitions

NASA Astrophysics Data System (ADS)

We consider the lowest order interaction of the Foldy-Wouthuysen QED and QCD Hamiltonian in the Coulomb gauge approach, to describe radiative transitions between conventional and hybrids charmonium mesons. The results are compared to potential quark models and lattices calculations.

Gou, Peng; Yépez-Martínez, Tochtli; Szczepaniak, Adam P.

2015-01-01

192

Yukawa unification predictions for the LHC

NASA Astrophysics Data System (ADS)

This paper is divided into two parts. In the first part we analyze the consequences, for the LHC, of gauge and third-family Yukawa coupling unification with a particular set of boundary conditions defined at the grand unification scale. We perform a global ?2 analysis including the observables MW, MZ, GF, ?em-1, ?s(MZ), Mt, mb(mb), M?, BR(B?Xs?), BR(Bs??+?-), and Mh. The fit is performed in the minimal supersymmetric Standard Model in terms of nine grand unification-scale parameters, while tan?? and ? are fixed at the weak scale. Good fits suggest an upper bound on the gluino mass, Mg˜?2TeV. This constraint comes predominantly from fitting the bottom-quark and Higgs masses (assuming a 125 GeV Higgs). Gluinos should be visible at the LHC in the 14 TeV run but they cannot be described by the typical simplified models. This is because the branching ratios for g˜?tt¯?˜1,20, bb¯?˜1,20, tb¯?˜1,2-, bt¯?˜1,2+, g?˜1,2,3,40 are comparable. Top squarks and sbottoms may also be visible. Charginos and neutralinos can be light, with the lightest supersymmetric particle predominantly bino-like. In the second part of the paper we analyze a complete three-family model and discuss the quality of the global ?2 fits and the differences between the third-family analysis and the full three-family analysis for overlapping observables. We note that the light Higgs in our model couples to matter like the Standard Model Higgs. Any deviation from this would rule out this model.

Anandakrishnan, Archana; Raby, Stuart; Wingerter, Ak?n

2013-03-01

193

One-dimensional Coulomb problem in Dirac materials

We investigate the one-dimensional Coulomb potential with application to a class of quasirelativistic systems, so-called Dirac-Weyl materials, described by matrix Hamiltonians. We obtain the exact solution of the shifted and truncated Coulomb problems, with the wavefunctions expressed in terms of special functions (namely Whittaker functions), whilst the energy spectrum must be determined via solutions to transcendental equations. Most notably, there are critical bandgaps below which certain low-lying quantum states are missing in a manifestation of atomic collapse.

C. A. Downing; M. E. Portnoi

2014-11-21

194

New ideas for Yukawa interactions and the origin of mass

NASA Astrophysics Data System (ADS)

I explore new ideas in the Yukawa sector of the Standard Model. Very little is known experimentally about the Yukawa sector. We have yet to discover the Higgs boson. We have not experimentally measured the Yukawa couplings. Because so little is known, this is a good area to explore changes to the Standard Model. The gauge sector has been extremely successful in predicting experimental results. This makes any modifications severely constrained. I discuss four ways in which modifying the Yukawa sector can produce interesting results that can be tested experimentally at colliders. In chapter 2 dimension 6 operators, instead of the usual dimension 4 operators, are used to give mass to the fermions. If this theory is correct, it broadens the recent exclusion range for the mass of the Higgs boson from the Tevatron and also increases the double Higgs production. In chapter 3 a Froggatt-Nielsen mechanism is used to generate the masses and mixings of the quarks in the Standard Model. The Yukawa couplings in this model are all of a similar order. The hierarchy of masses in the Standard Model is generated through higher order interactions involving vector-like quarks and singlet scalars. I show that in one parameterization the Higgs diphoton signal is increased by a factor of 10. This mode is very good for early Higgs searches at the LHC. In chapter 4 a fourth generation is added to the MSSM. Limits are placed on the masses of fourth generation particles based on the perturbativity of their Yukawa couplings. We place very stringent limits on the parameter tan beta and the masses for the b' and t' quarks. In order to broaden these limits we construct a model in which the Yukawa couplings are modified by the introduction of new heavy vector-like quarks. In chapter 5 the problem of Neutrino mass is discussed. We introduce a new way to give masses to neutrinos by fine tuning the values of two different Yukawa coupling matrices. This allows us to have a right handed neutrino that has a mass of about 100 GeV. The new Yukawa interactions change the decay modes of the Higgs drastically, and can be tested at the LHC.

Murdock, Zeke

195

On the Sharp Surface Model for Coulomb and Nuclear Interactions Between Two Deformed Nuclei

NASA Astrophysics Data System (ADS)

The Coulomb and nuclear heavy ion (HI) potentials are derived for an interacting pair of deformed nuclei assuming sharp surface model for each nucleus. The orientation and separation dependences of the Coulomb and nuclear interactions are studied. It is assumed 238U + 238U as an example, and the effect of quadrupole term is investigated. For the nuclear potential part based on M3Y nucleon-nucleon interaction, the sharp surface model shows much difference compared with the more accurate frequently used multipole expansion method while the success of this model in calculating the Coulomb potential between this deformed pair of nuclei exists in the physically important surface region.

Ismail, M.; Ellithi, A. Y.; El Gebaly, H.; Botros, M. M.; Adel, A.

196

Dynamical rigidity of stochastic Coulomb systems in infinite-dimensions

This paper is based on the talk in "Probability Symposium" at Research Institute of Mathematical Sciences (Kyoto University) on 2013/12/18, and gives an announcement of some parts of the results in [1,8,10,11]. We show two instances of dynamical rigidity of Ginibre interacting Brownian motion in infinite dimensions. This stochastic dynamics is given by the infinite-dimensional stochastic differential equation describing infinite-many Brownian particles in the plane interacting through two-dimensional Coulomb potential. The first dynamical rigidity is that the Ginibre interacting Brownian motion is a unique, strong solution of two different infinite dimensional stochastic differential equations. The second shows that the tagged particles of Ginibre interacting Brownian motion are sub diffusive. We also propose the notion of "Coulomb random point fields" and the associated "Coulomb interacting Brownian motions".

Hirofumi Osada

2014-05-23

197

Nonasymptotic analysis of relativistic electron scattering in the Coulomb field

It is shown that the conventional Born series for relativistic electron scattering in the Coulomb field cannot be used for calculating the scattering characteristics. The differential cross section at small scattering angles is found on the basis of the Furry-Sommerfeld-Maue solution of the Dirac equation. Propagation of the electron wave packet is considered in order to separate the incident and scattered fluxes. It is shown that the total scattering cross section proves to be finite but depends on the distance r between the scattering center and the observation point. It is also shown that the polarization characteristics of the scattered beam are changed due to the long-range character of the Coulomb potential. The results can be important because Coulomb scattering is often used for normalization of experimental data in high-energy physics.

Feranchuk, I. D.; Skoromnik, O. D. [Belarusian State University, 4 Nezavisimosty Avenue, BY-220030 Minsk (Belarus)

2010-11-15

198

Nonasymptotic analysis of relativistic electron scattering in the Coulomb field

NASA Astrophysics Data System (ADS)

It is shown that the conventional Born series for relativistic electron scattering in the Coulomb field cannot be used for calculating the scattering characteristics. The differential cross section at small scattering angles is found on the basis of the Furry-Sommerfeld-Maue solution of the Dirac equation. Propagation of the electron wave packet is considered in order to separate the incident and scattered fluxes. It is shown that the total scattering cross section proves to be finite but depends on the distance r between the scattering center and the observation point. It is also shown that the polarization characteristics of the scattered beam are changed due to the long-range character of the Coulomb potential. The results can be important because Coulomb scattering is often used for normalization of experimental data in high-energy physics.

Feranchuk, I. D.; Skoromnik, O. D.

2010-11-01

199

Numerical studies of the melting transition in 2D Yukawa systems

We present the latest results of our systematic studies of the solid--liquid phase transition in 2D classical many-particle systems interacting with the Yukawa potential. Our previous work is extended by applying the molecular dynamic simulations to systems with up to 1.6 million particles in the computational box (for {kappa} = 2 case). Equilibrium simulations are performed for different coupling parameters in the vicinity of the expected melting transition ({gamma}{sub m}{sup {kappa}}{sup ={sup 2}}{approx_equal}415) and a wide range of observables are averaged over uncorrelated samples of the micro-canonical ensemble generated by the simulations.

Hartmann, P.; Donko, Z. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Kalman, G. J. [Department of Physics, Boston College, Chestnut Hill, MA 02467 (United States)

2008-09-07

200

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

201

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

The thermodynamic properties of strong short-range attractive Yukawa fluids, ? = 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 at lower temperatures, where dynamics turns glassy. To obtain the surface tension we employed, for both methods, a procedure that yields the pressure tensor components for discontinuous potentials. The surface tension results obtained by the standard MC and REMC techniques are in good agreement. PMID:21513403

Odriozola, G; Bárcenas, M; Orea, P

2011-04-21

202

Thermodynamic behavior of the generalized scalar Yukawa model in a magnetic background

NASA Astrophysics Data System (ADS)

We study the thermodynamic behavior of the generalized scalar Yukawa model, composed of a complex scalar field interacting with scalar and vector fields. Thermal effects are treated in the framework of generalized zeta-functions. For the case of vanishing effective chemical potential, we find a vanishing contribution from the vector field. We focus on the analysis of the phase structure of this model at effective chemical equilibrium, under change of values of the relevant parameters of the model, looking specially to the influence of the magnetic background on the phase structure.

Abreu, L. M.; Malbouisson, A. P. C.; Malbouisson, J. M. C.; Nery, E. S.; Rodrigues da Silva, R.

2014-04-01

203

Modified coulomb law in a strongly magnetized vacuum.

We study the electric potential of a charge placed in a strong magnetic field B>B(0) approximately 4.4x10(13) G, as modified by the vacuum polarization. In such a field the electron Larmour radius is much less than its Compton length. At the Larmour distances a scaling law occurs, with the potential determined by a magnetic-field-independent function. The scaling regime implies short-range interaction, expressed by the Yukawa law. The electromagnetic interaction regains its long-range character at distances larger than the Compton length, the potential decreasing across B faster than along. Correction to the nonrelativistic ground-state energy of a hydrogenlike atom is found. In the limit B = infinity, the modified potential becomes the Dirac delta function plus a regular background. With this potential the ground-state energy is finite--the best pronounced effect of the vacuum polarization. PMID:17501547

Shabad, Anatoly E; Usov, Vladimir V

2007-05-01

204

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

205

The interaction between colloidal particles is well represented by a hard-core two-Yukawa potential. In order to assess the accuracy of theoretical predictions for the thermodynamic and structural properties of mixed colloids, standard Monte Carlo simulations are carried out for the hard-core two-Yukawa mixtures. In the simulations, one range parameter in the two-Yukawa potential is taken as 1.8 or 2.8647, and another is taken as 4, 8, or 13.5485. Both attractive and repulsive dominant cases of the potential outside the hard core are considered. The effects of temperature, density, composition, size and energy parameter ratios on internal energy, compressibility factor, and radial distribution function are investigated extensively. Theoretical calculations are performed in the framework of analytical solution for the Ornstein-Zernike equation with the first-order mean spherical approximation (FMSA). Our analysis shows that the FMSA is very accurate for the prediction of the compressibility factor of the hard-core two-Yukawa mixtures at all conditions studied. The FMSA generally predicts accurate internal energy, but overestimates the internal energy of the systems at lower temperatures. Furthermore, we found that a simplified exponential version of the FMSA predicts fairly good radial distribution function at contact for the mixed two-Yukawa fluids. The comparison of the theoretical compressibility factor with that from the Monte Carlo simulations suggests that the FMSA can be used to investigate the fluid-fluid equilibria of hard-core two-Yukawa mixtures. PMID:18190220

Yu, Yang-Xin; Jin, Lin

2008-01-01

206

Yukawa and the Birth of Meson Theory: Fiftieth Anniversary for Nuclear Forces.

ERIC Educational Resources Information Center

In 1935 physicist Hideki Yukawa proposed the meson theory of nuclear forces. Background, influences, and chronology of Yukawa's work are presented and discussed. Yukawa was supported in his meson idea by Japan's strong emphasis on intuitive and creative approaches which are also evident in subsequent developments in that country. (DH)

Spradley, Joseph L.

1985-01-01

207

(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

208

The liquid-vapor phase diagram and surface tension for hard-core Yukawa potential with 4

Duda, Yurko; Romero-Martínez, Ascención; Orea, Pedro

2007-06-14

209

Gravitational Corrections to Yukawa and phi{sup 4} Interactions

We consider the lowest order quantum gravitational corrections to Yukawa and phi{sup 4} interactions. Our results show that quantum gravity leads to contributions to the running coupling constants if the particles are massive and therefore alters the scaling behavior of the standard model. Furthermore, we find that the gravitational contributions to the running of the masses vanish.

Rodigast, Andreas; Schuster, Theodor [Institut fuer Physik, Humboldt Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany)

2010-02-26

210

Gravitational corrections to Yukawa and phi{4} interactions.

We consider the lowest order quantum gravitational corrections to Yukawa and phi{4} interactions. Our results show that quantum gravity leads to contributions to the running coupling constants if the particles are massive and therefore alters the scaling behavior of the standard model. Furthermore, we find that the gravitational contributions to the running of the masses vanish. PMID:20366925

Rodigast, Andreas; Schuster, Theodor

2010-02-26

211

Hideki Yukawa January 23, 1907 - September 8, 1981---

Hideki Yukawa took the first step in his research in 1929 as an associate at Kyoto Imperial University (nowadays called Kyoto University). Most Japanese physicists of those days were isolated far from Western centers of physical science, where the `Sturm und Drang' of astonighing developments in the twentieth century physics had been roaring. There were only a handful of physicists

Yasutaka Tanikawa

1981-01-01

212

On the shear viscosity of 3D Yukawa liquids

We report calculations of the shear viscosity of three-dimensional strongly-coupled Yukawa liquids, based on two different non-equilibrium molecular dynamics methods. The present simulations intend to improve the accuracy of shear viscosity data, compared to those obtained in earlier studies.

Donko, Z.; Hartmann, P. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-l525 Budapest, P.O. Box 49 (Hungary)

2008-09-07

213

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

214

PREFACE: Strongly Coupled Coulomb Systems 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), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas, condensed matter and ultra-cold plasmas. One hundred and thirty participants came from twenty countries and four continents to participate in the conference. Those giving presentations were asked to contribute to this special issue to make a representative record of an interesting conference. We thank the International Advisory Board and the Programme Committee for their support and suggestions. We thank the Local Organizing Committee (Stefania De Palo, Vittorio Pellegrini, Andrea Perali and Pierbiagio Pieri) for all their efforts. We highlight for special mention the dedication displayed by Andrea Perali, by Rocco di Marco for computer support, and by our tireless conference secretary Fiorella Paino. The knowledgeable guided tour of the historic centre of Camerino given by Fiorella Paino was appreciated by many participants. It is no exaggeration to say that without the extraordinary efforts put in by these three, the conference could not have been the success that it was. For their sustained interest and support we thank Fulvio Esposito, Rector of the University of Camerino, Fabio Beltram, Director of NEST, Scuola Normale Superiore, Pisa, and Daniel Cox, Co-Director of ICAM, University of California at Davis. We thank the Institute of Complex and Adaptive Matter ICAM-I2CAM, USA for providing a video record of the conference on the web (found at http://sccs2008.df.unicam.it/). Finally we thank the conference sponsors for their very generous support: the University of Camerino, the Institute of Complex and Adaptive Matter ICAM-I2CAM, USA, the International Centre for Theoretical Physics ICTP Trieste, and CNR-INFM DEMOCRITOS Modeling Center for Research in Atomistic Simulation, Trieste. Participants at the International Conference on Strongly Coupled Coulomb Systems (SCCS) (University of Camerino, Italy, 29 July-2 August 2008).

Neilson, David; Senatore, Gaetano

2009-05-01

215

Phase structure and Higgs boson mass in a Higgs-Yukawa model with a dimension-6 operator

We investigate the impact of a $\\lambda_6 \\varphi^6$ term included in a chirally invariant lattice Higgs-Yukawa model. Such a term could emerge from BSM physics at some larger energy scale. We map out the phase structure of the Higgs-Yukawa model with positive $\\lambda_6$ and negative quartic self coupling of the scalar fields. To this end, we evaluate the constraint effective potential in lattice perturbation theory and also determine the magnetization of the model via numerical simulations which allow us to reach also non-perturbative values of the couplings. As a result, we find a complex phase structure with first and second order phase transitions identified through the magnetization. Further we analyze the effect of such a $\\varphi^6$ term on the lower Higgs boson mass bound to see, whether the standard model lower mass bound can be altered.

David Y. -J. Chu; Karl Jansen; Bastian Knippschild; C. -J. David Lin; Kei-Ichi Nagai; Attila Nagy

2015-01-01

216

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

217

Role of the Coulomb singularity in high-order harmonic generation

NASA Astrophysics Data System (ADS)

High-order harmonic generation (HHG) from a single hydrogen atom is studied analytically and numerically in the regime of small Keldysh parameter. The HHG spectra from different Coulomb-like model potentials, such as soft-core and/or one-dimensional (1D) potentials are compared to the three-dimensional (3D) Coulomb potential. It is shown, using analytic arguments, that the famous plateau in the HHG spectrum owes its existence to the Coulomb singularity, whereas soft-core potentials give spectra that fall off exponentially with increasing frequency. The idea is demonstrated numerically on a 3D soft-core potential that has the same long-range asymptotic behavior and ground-state energy as hydrogen. In addition, a number of widely used 1D Coulomb-like potentials are discussed. It is shown that in order that a 1D potential be a reasonable substitute for the 3D Coulomb potential, it must have a cusp singularity. A specific potential satisfying this criterion is proposed.

Gordon, Ariel; Santra, Robin; Kärtner, Franz X.

2005-12-01

218

Relativistic effects in the photoionization of hydrogen-like ions with screened Coulomb interaction

NASA Astrophysics Data System (ADS)

The relativistic effects in the photoionization of hydrogen-like ion with screened Coulomb interaction of Yukawa type are studied for a broad range of screening lengths and photoelectron energies. The bound and continuum wave functions have been determined by solving the Dirac equation. The study is focused on the relativistic effects manifested in the characteristic features of photoionization cross section for electric dipole nl ??,l±1 transitions: shape resonances, Cooper minima and cross section enhancements due to near-zero-energy states. It is shown that the main source of relativistic effects in these cross section features is the fine-structure splitting of bound state energy levels. The relativistic effects are studied in the photoionization of Fe25+ ion, as an example.

Xie, L. Y.; Wang, J. G.; Janev, R. K.

2014-06-01

219

Coulomb screening in low-energy nuclear reactions

Coulomb screening effects are studied in very-low-energy nuclear reactions. The two-potential formalism is shown to be a convenient method for the separation of long-range (molecular) and short-range (nuclear) dynamics. As specific applications, electron screening effects and muon catalysis in nuclear reactions are investigated. In the case of electron screening in very-low-energy nuclear reactions a method is elaborated for calculation of

Gy. Bencze; C. Chandler

1992-01-01

220

The quantum mechanical two-Coulomb-centre problem in the Dirac equation framework in 2+1 dimensions

NASA Astrophysics Data System (ADS)

With the help of perturbation theory the asymptotic expansions (at small and large internuclear distances R) of the eigenvalues (potential curves) E(R) of the two-Coulomb-centre problem in 2+1 dimensions are obtained. We compare the results obtained with the data from similar approximation for two-Coulomb-centre problem in 3+1 dimensions.

Bondarchuk, V. V.; Shvab, I. M.

2007-06-01

221

Orientational order and topological defects in two-dimensional Yukawa systems

NASA Astrophysics Data System (ADS)

New numerical results concerned with formation of orientational order and topological defects in non-ideal systems of particles, interacted via screened Coulomb potential, are presented. Calculations have been performed in a wide range of parameters, corresponding to the experimental conditions in the laboratory dusty plasmas. Relations between a number of topological defects and shape of a bond-angular correlation function are obtained for the first time.

Vaulina, O. S.; Vasilieva, E. V.

2014-02-01

222

Energy density, heat capacity and diffusion constant in non-ideal Yukawa systems

NASA Astrophysics Data System (ADS)

The energy densities, the heat capacities and the diffusion constants in two- and three-dimensional non-ideal dissipative systems of particles interacting with the screened Coulomb potential are studied. A simple semi-empirical expression for the energy density is considered. New analytical relations between the diffusion constants and the energy density in strongly coupled systems are proposed. Comparison of theoretical results and numerical simulations is presented.

Vaulina, O. S.; Khrustalyov, Yu. V.; Petrov, O. F.; Fortov, V. E.

2010-02-01

223

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

224

Effective Hamiltonian for bound states in Yukawa theory

A generalization of the Gell-Mann–Low theorem is applied to lowest nontrivial order to determine an effective Hamiltonian for two-fermion states in relativistic Yukawa theory. The consistency of the corresponding effective Schrödinger equation is thoroughly investigated in various aspects, among others the nonrelativistic and one-body limits, and the small-distance or large-momentum regime of the bound state solutions is discussed in detail. -- Highlights: •A generalization of the Gell-Mann–Low theorem is applied to Yukawa theory. •The effective Hamiltonian for two-fermion states is derived to lowest order. •The nonrelativistic and one-body limits are consistent. •The large-momentum behavior of the bound-state solutions is analyzed. •A critical value for the coupling constant is determined.

Weber, Axel, E-mail: axel@ifm.umich.mx

2013-07-15

225

Yukawa Unification and Sparticle Spectroscopy in Gauge Mediation Models

We explore the implications of t-b-tau (and b-tau) Yukawa coupling unification condition on the fundamental parameter space and sparticle spectroscopy in the minimal gauge mediated supersymmetry breaking (mGMSB) model. We find that this scenario prefers values of the CP-odd Higgs mass m_A > 1 TeV, with all colored sparticle masses above 3 TeV. These predictions will be hard to test at LHC13 but they may be testable at HE-LHC 33 TeV or a 100 TeV collider. Both t-b-tau and b-tau Yukawa coupling unifications prefer a relatively light gravitino with mass < 30 eV, which makes it a candidate hot dark matter particle. However, it cannot account for more than 15 % of the observed dark matter density.

Gogoladze, Ilia; Shafi, Qaisar; Un, Cem Salih

2015-01-01

226

This is a sequel to a recent work of Gaudin, who studied the classical equilibrium statistical mechanics of the two-dimensional Coulomb gas on a lattice at a special value of the coupling constant Gamma such that the model is exactly solvable. This model is briefly reviewed, and it is shown that the correlation functions obey the sum rules that characterize a conductive phase. A related model in which the particles are constrained to move on an array of equidistant parallel lines has simpler mathematics, and the asymptotic behavior of its correlation functions is studied in some detail. In the low-density limit, the lattice model is expected to have the same properties as a system of charged, hard disks; the correlation functions, internal energy, and specific heat of the latter are discussed.

Cornu, F.; Jancovici, B.

1987-10-01

227

Coulomb impurity problem in graphene.

We address the problem of an unscreened Coulomb charge in graphene and calculate the local density of states and displaced charge as a function of energy and distance from the impurity. This is done nonperturbatively in two different ways: (1) solving the problem exactly by studying numerically the tight-binding model on the lattice and (2) using the continuum description in terms of the 2D Dirac equation. We show that the Dirac equation, when properly regularized, provides a qualitative and quantitative low energy description of the problem. The lattice solution shows extra features that cannot be described by the Dirac equation: namely, bound state formation and strong renormalization of the van Hove singularities. PMID:17995277

Pereira, Vitor M; Nilsson, Johan; Castro Neto, A H

2007-10-19

228

Coulomb drag mechanisms in graphene.

Recent measurements revealed an anomalous Coulomb drag in graphene, hinting at new physics at charge neutrality. The anomalous drag is explained by a new mechanism based on energy transport, which involves interlayer energy transfer, coupled to charge flow via lateral heat currents and thermopower. The old and new drag mechanisms are governed by distinct physical effects, resulting in starkly different behavior, in particular for drag magnitude and sign near charge neutrality. The new mechanism explains the giant enhancement of drag near charge neutrality, as well as its sign and anomalous sensitivity to the magnetic field. Under realistic conditions, energy transport dominates in a wide temperature range, giving rise to a universal value of drag which is essentially independent of the electron-electron interaction strength. PMID:23834416

Song, J C W; Abanin, D A; Levitov, L S

2013-08-14

229

Hideki Yukawa ---January 23, 1907 - September 8, 1981---

NASA Astrophysics Data System (ADS)

Hideki Yukawa took the first step in his research in 1929 as an associate at Kyoto Imperial University (nowadays called Kyoto University). Most Japanese physicists of those days were isolated far from Western centers of physical science, where the `Sturm und Drang' of astonighing developments in the twentieth century physics had been roaring. There were only a handful of physicists in Japan who had already set to work in quantum physics, but never any one working on the quantum field theory and theoretical nuclear physics. Yukawa had to initiate his study of these frontiers of physical science by himself, without any teacher or senior scholar in this field. In 1935, Yukawa published his first paper with the title ``On the Interaction of Elementary Particles. I'', in which he developed the revolutionary idea of the meson theory. Although even the term `elementary particle' was not so popular in those days, the meson theory was proposed as a unified theory of interactions of elementary particles. His theory opened up a new fundamental view of Nature. This event might be regarded as a miracle in the history of Japanese physics. Through all of his works and thoughts, we are impressed by the simplicity of approach, the unfailing intuition and the creativity of a great master, which are deep-rooted in his culture. A sketch of his life, mainly based on his autobiographical material and partly based on the present writer's personal recollection, is presented to show his thought and activity.

Tanikawa, Y.

1981-10-01

230

Coulomb-gas representation of the two-dimensional XY model on a torus

NASA Astrophysics Data System (ADS)

Superconducting networks and superfluid films in two dimensions are often described by a theoretical model in which the unique microscopic variables are phases. Among these models the XY model with Villain's interaction potential can be mapped exactly onto a lattice Coulomb gas. This is well known, but several questions still have no clear answers: First, what is the meaning of the charge of the Coulomb gas in terms of the original variables of the XY model\\? Second, how can the helicity modulus be expressed exactly in the Coulomb gas representation on a finite torus\\? In this paper we answer these questions. The mapping onto a lattice Coulomb gas is done in a way that differs from the usual one. This mapping is applied to a phase model whose partition function has an identical mathematical structure as the one of the XY model with Villain's interaction. For this phase model, contrary to the XY model, the charges of the Coulomb gas describe indeed exactly the topological charges as we can define them in terms of the phase variables. However, this Coulomb gas contains an additional polarization energy and two additional fictitious variables accounting for the specific topological character of the torus. The helicity modulus is exactly the inverse of a dielectric constant which can be defined as the linear response to an external uniform electric field, even on a torus. The meaning of the Coulomb-gas representation is also discussed in terms of the original variables of the XY model.

Vallat, A.; Beck, H.

1994-08-01

231

Role of the Permanent Dipole Moment in Coulomb Explosion

NASA Astrophysics Data System (ADS)

By numerically solving the non-Born—Oppenheimer time-dependent Schrödinger equation in a few-cycle chirped laser field (5-fs, 800-nm), the effect of the permanent dipole moment on the Coulomb explosion is studied by the kinetic-energy-release spectra with the “virtual detector" method. The results indicate that with the effect of the permanent dipole moment, different multiphoton processes for heteronuclear and homonuclear diatomic molecular ions may take place when the wave packets transit from the ground state (1s?g) to the first excited state (2p?u), and then move along the excited potential curve, and finally charge-resonant enhanced ionization occurs at critical internuclear distance. As a result, despite the similar ionization probabilities for these two systems at higher vibrational level with larger chirp parameter ?, the structure of the Coulomb explosion spectrum for the former is prominently different from that for the latter.

Zhang, Cai-Ping; Miao, Xiang-Yang

2013-10-01

232

Effect of Coulomb screening length on nuclear "pasta" simulations

NASA Astrophysics Data System (ADS)

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 semiclassical molecular dynamics model, studying isospin symmetric matter at subsaturation densities and low temperatures. The electrostatic interaction between protons is included as 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 nonhomogeneous nuclear structures known as "nuclear pasta." As the screening length increases, we can see 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 qualitative difference in the structure of neutron star matter at low temperatures shows that special caution should be taken when the screening length is estimated for numerical simulations.

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

2014-05-01

233

Coulomb repulsion in short polypeptides.

Coulomb repulsion between like-charged side chains is presently viewed as a major force that impacts the biological activity of intrinsically disordered polypeptides (IDPs) by determining their spatial dimensions. We investigated short synthetic models of IDPs, purely composed of ionizable amino acid residues and therefore expected to display an extreme structural and dynamic response to pH variation. Two synergistic, custom-made, time-resolved fluorescence methods were applied in tandem to study the structure and dynamics of the acidic and basic hexapeptides Asp6, Glu6, Arg6, Lys6, and His6 between pH 1 and 12. (i) End-to-end distances were obtained from the short-distance Förster resonance energy transfer (sdFRET) from N-terminal 5-fluoro-l-tryptophan (FTrp) to C-terminal Dbo. (ii) End-to-end collision rates were obtained for the same peptides from the collision-induced fluorescence quenching (CIFQ) of Dbo by FTrp. Unexpectedly, the very high increase of charge density at elevated pH had no dynamical or conformational consequence in the anionic chains, neither in the absence nor in the presence of salt, in conflict with the common view and in partial conflict with accompanying molecular dynamics simulations. In contrast, the cationic peptides responded to ionization but with surprising patterns that mirrored the rich individual characteristics of each side chain type. The contrasting results had to be interpreted, by considering salt screening experiments, N-terminal acetylation, and simulations, in terms of an interplay of local dielectric constant and peptide-length dependent side chain charge-charge repulsion, side chain functional group solvation, N-terminal and side chain charge-charge repulsion, and side chain-side chain as well as side chain-backbone interactions. The common picture that emerged is that Coulomb repulsion between water-solvated side chains is efficiently quenched in short peptides as long as side chains are not in direct contact with each other or the main chain. PMID:25470659

Norouzy, Amir; Assaf, Khaleel I; Zhang, Shuai; Jacob, Maik H; Nau, Werner M

2015-01-01

234

Momentum-space treatment of Coulomb interaction in three-nucleon reactions with two protons

The Coulomb interaction between the two protons is included in the calculation of proton-deuteron elastic scattering, radiative proton-deuteron capture and two-body electromagnetic disintegration of ${}^3\\mathrm{He}$. The hadron dynamics is based on the purely nucleonic charge-dependent (CD) Bonn potential and its realistic extension CD Bonn + $\\Delta$ to a coupled-channel two-baryon potential, allowing for single virtual $\\Delta$-isobar excitation. Calculations are done using integral equations in momentum space. The screening and renormalization approach is employed for including the Coulomb interaction. Convergence of the procedure is found already at moderate screening radii. The reliability of the method is demonstrated. The Coulomb effect on observables is seen at low energies for the whole kinematic regime. In proton-deuteron elastic scattering at higher energies the Coulomb effect is confined to forward scattering angles; the $\\Delta$-isobar effect found previously remains unchanged by Coulomb. In electromagnetic reactions Coulomb competes with other effects in a complicated way.

A. Deltuva; A. C. Fonseca; P. U. Sauer

2005-03-04

235

Light-Front Quantization with Explicit Lorentz Symmetry for Yukawa Model

NASA Astrophysics Data System (ADS)

The Dirac method for constrained systems is incomplete for the light-front (LF) quantization of the Yukawa model in D = 1 + 1 dimensions. A novel quantization procedure is proposed, where one obtains the LF commutator and anti-commutators directly from the Heisenberg equations generated by P +, which is a kinematical operator. By adding the general assumptions on the quantum field theory, one evalutes 2-point Wightman functions for a free field case. The Lorentz symmetry is manifest at every step of this novel LF procedure. The Gaussian effective potential is defined with the point-splitting regularization with a space-like separation. The optimum values of the mass parameters are regularization independent.

Przeszowski, Jerzy A.; ?ochowski, Jan

2014-12-01

236

Critical parameters of hard-core Yukawa fluids within the structural theory

NASA Astrophysics Data System (ADS)

A purely statistical mechanical approach is proposed to account for the liquid-vapor critical point based on the mean density approximation (MDA) of the direct correlation function. The application to hard-core Yukawa (HCY) fluids facilitates the use of the series mean spherical approximation (SMSA). The location of the critical parameters for HCY fluid with variable intermolecular range is accurately calculated. Good agreement is observed with computer simulation results and with the inverse temperature expansion (ITE) predictions. The influence of the potential range on the critical parameters is demonstrated and the universality of the critical compressibility ratio is discussed. The behavior of the isochoric and isobaric heat capacities along the equilibrium line and the near vicinity of the critical point is discussed in details.

Bahaa Khedr, M.; Osman, S. M.

2012-10-01

237

Thermodynamic properties of short-range attractive Yukawa fluid: simulation and theory.

Coexistence properties of the hard-core attractive Yukawa potential with inverse-range parameter kappa=9, 10, 12, and 15 are calculated by applying canonical Monte Carlo simulation. As previously shown for longer ranges, we show that also for the ranges considered here the coexistence curves scaled by the critical density and temperature obey the law of corresponding states, and that a linear relationship between the critical density and the reciprocal of the critical temperature holds. The simulation results are compared to the predictions of the self-consistent Ornstein-Zernike approximation, and a good agreement is found for both the critical points and the coexistence curves, although some slight discrepancies are present. PMID:20331282

Orea, Pedro; Tapia-Medina, Carlos; Pini, Davide; Reiner, Albert

2010-03-21

238

Electroweak unification of Yukawa Couplings in the Extension of the Two Higgs Doublet Model

NASA Astrophysics Data System (ADS)

In the simplest extension of the Standard Model (SM), known as the Two Higgs Doublet Model (2HDM), a second doublet of scalar fields and a new potential are introduced, the last one depends on seven parameters that determine the masses of the five Higgs bosons that are predicted by the model. We use the one loop renormalization group equations (RGE) to study the mass spectrum of the five particles. The study was conducted in a electroweak unification of Yukawa couplings scenario, with the purpose of reducing the number of parameters of the model and to determine the influence of this consideration in the development of the RGE. The objective of this study is to analytically evaluate the bounds on the quartic couplings and numerically evaluate the energy dependence of the particles masses.

Morales C., D.; Juárez W., S. R.; Kielanowski, P.

2011-09-01

239

The LAGEOS satellites orbit and Yukawa-like interactions

NASA Astrophysics Data System (ADS)

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, or instead break it, giving rise to new phenomena. Among the several techniques useful for the search of this additional physics to the various scales, the accurate measurements of the pericenter shift ? ? of binary systems may be used to test for a new-long-range-interaction (NLRI) with a characteristic range comparable with the system semimajor axis. These very weak NLRI are usually described by means of a Yukawa-like potential with strength ? and range ? . The LAGEOS satellites, thanks to the very accurate determination of their orbit through the powerful Satellite Laser Ranging (SLR) technique, could be considered the best candidates for the study of these NLRI. Indeed, the SLR technique tracks the orbit of the LAGEOS satellites with an accuracy approaching the cm value in range. We are then able to determine their orbital elements with about the same accuracy. In particular LAGEOS II pericenter, thanks to the higher orbital eccentricity e (about 0.014) with respect to LAGEOS (about 0.004), could be considered the best probe. Indeed, in the case of the pericenter the measurement quantity is ea? ? , with a the satellite semimajor axis (about 12,163 km). For instance, assuming that we are able to fit LAGEOS II orbit to a 3 cm level over 1 year, we obtain an estimate for the constraining of ? of about 8\\cdot 10-11 at a range ? of about 1 Earth radii. Of course, this estimate does not include the contributions from the systematic errors due to the various gravitational and non-gravitational perturbations, which are necessary to be considered in order to estimate an accurate error budget. In the present work we will focus on the constraints in ? that can be obtained with the actual gravity field solution EGM96 (? < 1.2\\cdot 10-10 from the even zonal harmonics uncertainties) and also with the first promising solutions from the CHAMP (? < 8.3\\cdot 10-11) and GRACE (? < 5.6\\cdot 10-11) missions. These results represent an improvement of two or three order-of-magnitude with respect to the best constraints obtained in the past with LAGEOS (? ? ? < 10-5-10-8). The impact of the non-gravitational perturbations mismodelling in the final error budget will be given together with the improvements obtainable in the constraint of the strength ? with the proposed LARES satellite, which will be characterised by a larger eccentricity with respect to LAGEOS II.

Lucchesi, D. M.

240

The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards 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 isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.

J. Diriken; I. Stefanescu; D. Balabanski; N. Blasi; A. Blazhev; N. Bree; J. Cederkäll; T. E. Cocolios; T. Davinson; J. Eberth; A. Ekström; D. V. Fedorov; V. N. Fedosseev; L. M. Fraile; S. Franchoo; G. Georgiev; K. Gladnishki; M. Huyse; O. V. Ivanov; V. S. Ivanov; J. Iwanicki; J. Jolie; T. Konstantinopoulos; Th. Kröll; R. Krücken; U. Köster; A. Lagoyannis; G. Lo Bianco; P. Maierbeck; B. A. Marsh; P. Napiorkowski; N. Patronis; D. Pauwels; P. Reiter; M. Seliverstov; G. Sletten; J. Van de Walle; P. Van Duppen; D. Voulot; W. B. Walters; N. Warr; F. Wenander; K. Wrzosek

2010-10-13

241

Crystallization in two-component Coulomb systems.

The analysis of Coulomb crystallization is extended from one-component to two-component plasmas. Critical parameters for the existence of Coulomb crystals are derived for both classical and quantum crystals. In the latter case, a critical mass ratio of the two charged components is found, which is of the order of 80. Thus, holes in semiconductors with sufficiently flat valence bands are predicted to spontaneously order into a regular lattice. Such hole crystals are intimately related to ion Coulomb crystals in white dwarf and neutron stars as well as to ion crystals produced in the laboratory. A unified phase diagram of two-component Coulomb crystals is presented and is verified by first-principles computer simulations. PMID:16384315

Bonitz, M; Filinov, V S; Fortov, V E; Levashov, P R; Fehske, H

2005-12-01

242

NASA Astrophysics Data System (ADS)

Coulomb final-state interaction of positive charged kaons in heavy ion reactions and its impact on the kaon transverse flow and the kaon azimuthal distribution are investigated within the framework of QMD (quantum molecular dynamics) model. The Coulomb interaction is found to tend to draw the flow of kaons away from that of nucleons and lead to a more isotropic azimuthal distribution of kaons in the target rapidity region. The recent FOPI data have been analyzed by taking into account both the Coulomb interaction and a kaon in-medium potential of the strong interaction. Although the effect of the kaon Coulomb potential on the kaon flow and azimuthal distribution is much smaller than that of the strong potential, it is found to be visible, and therefore, should be taken into account if one wants to extract unambiguous information about the kaon strong potential in nuclear matter from the kaon flow and azimuthal distribution data.

Wang, Z. S.; Faessler, Amand; Fuchs, C.; Uma Maheswari, V. S.; Kosov, D.

1998-01-01

243

NASA Astrophysics Data System (ADS)

In this letter, we present exact solutions of the Dirac equation with the mixed scalar-vector-pseudoscalar spatially dependent mass Coulomb potential under spin and pseudospin (p-spin) symmetry limits in 1+1 dimensions.

Rajabi, A. A.; Hamzavi, M.

2013-11-01

244

Quasi-exactly solvable relativistic soft-core Coulomb models

By considering a unified treatment, we present quasi exact polynomial solutions to both the Klein-Gordon and Dirac equations with the family of soft-core Coulomb potentials V{sub q}(r)=-Z/(r{sup q}+{beta}{sup q}){sup 1/q}, Z>0, {beta}>0, q{>=}1. We consider cases q=1 and q=2 and show that both cases are reducible to the same basic ordinary differential equation. A systematic and closed form solution to the basic equation is obtained using the Bethe ansatz method. For each case, the expressions for the energies and the allowed parameters are obtained analytically and the wavefunctions are derived in terms of the roots of a set of Bethe ansatz equations. - Highlights: Black-Right-Pointing-Pointer The relativistic bound-state solutions of the soft-core Coulomb models. Black-Right-Pointing-Pointer Quasi-exact treatments of the Dirac and Klein-Gordon equations for the soft-core Coulomb models. Black-Right-Pointing-Pointer Solutions obtained in terms of the roots to the Bethe ansatz equations. Black-Right-Pointing-Pointer The hidden Lie algebraic structure discussed for the models. Black-Right-Pointing-Pointer Results useful in describing mesonic atoms and interaction of intense laser fields with atom.

Agboola, Davids, E-mail: davagboola@gmail.com; Zhang, Yao-Zhong, E-mail: yzz@maths.uq.edu.au

2012-09-15

245

Beam-Plasma Instabilities in a 2D Yukawa Lattice

We consider a 2D Yukawa lattice of grains, with a beam of other charged grains moving in the lattice plane. In contrast to Vlasov plasmas, where the electrostatic instability excited by the beam is only longitudinal, here both longitudinal and transverse instabilities of the lattice phonons can develop. We determine and compare the transverse and longitudinal growth rates. The growth rate spectrum in wave number space exhibits remarkable gaps where no instability can develop. Depending on the system parameters, the transverse instability can be selectively excited.

Kyrkos, S. [Department of Chemistry and Physics, Le Moyne College, Syracuse, New York 13214 (United States); Kalman, G. J. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Rosenberg, M. [Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093 (United States)

2009-06-05

246

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

247

On the defect induced gauge and Yukawa fields in graphene

We consider lattice deformations (both continuous and topological) in the hexagonal lattice Hubbard model in the tight binding approximation to graphene, involving operators with the range up to next-to-neighbor. In the low energy limit, we find that these deformations give rise to couplings of the electronic Dirac field to an external scalar (Yukawa) and gauge fields. The fields are expressed in terms of original defects. As a by-product we establish that the next-to-nearest order is the minimal range of deformations which produces the complete gauge and scalar fields. We consider an example of Stone--Wales defect, and find the associated gauge field.

Corneliu Sochichiu

2011-03-08

248

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

NASA Astrophysics Data System (ADS)

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.

Ortakaya, Sami

2013-11-01

249

Dirac-Hulthén Problem Within Coulomb-Hulthén Tensor Interaction Via SUSYQM

NASA Astrophysics Data System (ADS)

We solve the Dirac equation for the Hulthén potential with Coulomb-Hulthén tensor interaction for arbitrary spin-orbit coupling quantum number ? by using the supersymmetric quantum mechanics and a proper approximation to the centrifugal term. The effect of tensor interaction and parameters of potential on the energy of the system are also discussed.

Ikot, A. N.; Etuk, Sunday E.; Yazarloo, B. H.; Zarrinkamar, S.; Hassanabadi, H.

2015-01-01

250

Split Sfermion Families, Yukawa Unification and Muon g-2

We consider two distinct classes of Yukawa unified supersymmetric SO(10) models with non-universal and universal soft supersymmetry breaking (SSB) gaugino masses at M_{\\rm GUT}. In both cases, we assume that the third family SSB sfermion masses at M_{\\rm GUT} are different from the corresponding sfermion masses of the first two families (which are equal). For the SO(10) model with essentially arbitrary (non-universal) gaugino masses at M_{\\rm GUT}, it is shown that t-b-\\tau Yukawa coupling unification is compatible, among other things, with the 125 GeV Higgs boson mass, the WMAP relic dark matter density, and with the resolution of the apparent muon g-2 anomaly. The colored sparticles in this case all turn out to be quite heavy, of order 5 TeV or more, but the sleptons (smuon and stau) can be very light, of order 200 GeV or so. For the SO(10) model with universal gaugino masses and NUHM2 boundary conditions, the muon g-2 anomaly cannot be resolved. However, the gluino in this class of models is not too heavy, \\lesssim 3 TeV, and therefore may be found at the LHC.

M. Adeel Ajaib; Ilia Gogoladze; Qaisar Shafi; Cem Salih Un

2014-02-20

251

Split Sfermion Families, Yukawa Unification and Muon g-2

We consider two distinct classes of Yukawa unified supersymmetric SO(10) models with non-universal and universal soft supersymmetry breaking (SSB) gaugino masses at M_{\\rm GUT}. In both cases, we assume that the third family SSB sfermion masses at M_{\\rm GUT} are different from the corresponding sfermion masses of the first two families (which are equal). For the SO(10) model with essentially arbitrary (non-universal) gaugino masses at M_{\\rm GUT}, it is shown that t-b-\\tau Yukawa coupling unification is compatible, among other things, with the 125 GeV Higgs boson mass, the WMAP relic dark matter density, and with the resolution of the apparent muon g-2 anomaly. The colored sparticles in this case all turn out to be quite heavy, of order 5 TeV or more, but the sleptons (smuon and stau) can be very light, of order 200 GeV or so. For the SO(10) model with universal gaugino masses and NUHM2 boundary conditions, the muon g-2 anomaly cannot be resolved. However, the gluino in this class of models is not too heavy,...

Ajaib, M Adeel; Shafi, Qaisar; Un, Cem Salih

2014-01-01

252

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

253

SO(10) grand unified theories with dynamical Yukawa couplings

NASA Astrophysics Data System (ADS)

Renormalizable SO(10) grand unified theories (GUTs), extended by O(Ng)F family gauge symmetry, generate minimal supersymmetric Standard Model flavor structure dynamically via vacuum expectation values of "Yukawon" Higgs multiplets. For concrete illustration and calculability, we work with the fully realistic minimal supersymmetric GUTs based on the 210?126 ¯?126 GUT Higgs system—which were already parameter counting minimal relative to other realistic models. SO(10) fermion Higgs channels 126 ¯,10(120) extend to symmetric (antisymmetric) representations of O(Ng)F, while 210,126 are symmetric. Ng=3 dynamical Yukawa generation reduces the matter fermion Yukawas from 15 to 3 (21 to 5) without (with) the 120 Higgs. Yukawon GUTs are thus ultraminimal in parameter counting terms. Consistent symmetry breaking is ensured by a hidden sector Bajc-Melfo superpotential with a pair of symmetric O(Ng) multiplets ?,S, of which the latter's singlet part Ss breaks supersymmetry and the traceless part S ^ furnishes flat directions to cancel the O(Ng) D-term contributions of the visible sector. Novel dark matter candidates linked to flavor symmetry arise from both the Bajc-Melfo sector and GUT sector minimal supersymmetric Standard Model singlet pseudo-Goldstones. These relics may be viable light (<50 GeV) cold dark matter as reported by DAMA/LIBRA. In contrast to the new minimal supersymmetric SO(10) grand unified theory (NMSGUT) even sterile neutrinos can appear in certain branches of the flavor symmetry breaking without the tuning of couplings.

Aulakh, Charanjit S.; Khosa, Charanjit K.

2014-08-01

254

LHC Phenomenology of SO(10) Models with Yukawa Unification II

In this paper we study Yukawa-unified SO(10) SUSY GUTs with two types of SO(10) boundary conditions: (i) universal gaugino masses and (ii) non-universal gaugino masses with effective "mirage" mediation. With these boundary conditions, we perform a global chi^2 analysis to obtain the parameters consistent with 11 low energy observables, including the top, bottom, and tau masses. Both boundary conditions have universal scalar masses and "just so" splitting for the up- and down-type Higgs masses. In these models, the third family scalars are lighter than the first two families and the gauginos are lighter than all the scalars. We therefore focus on the gluino phenomenology in these models. In particular, we estimate the lowest allowed gluino mass in our models coming from the most recent LHC data and compare these to limits obtained using simplified models. We find that the lower bound on M_gluino in Yukawa-unified SO(10) SUSY GUTs is generically ~1.2 TEV at the 1 sigma level unless there is considerable degener...

Anandakrishnan, Archana; Raby, Stuart

2014-01-01

255

LHC phenomenology of SO(10) models with Yukawa unification. II.

NASA Astrophysics Data System (ADS)

In this paper we study Yukawa-unified SO(10) supersymmetric (SUSY) grand unified theories (GUTs) with two types of SO(10) boundary conditions: (i) universal gaugino masses and (ii) nonuniversal gaugino masses with effective "mirage" mediation. With these boundary conditions, we perform a global ?2 analysis to obtain the parameters consistent with 11 low energy observables, including the top, bottom, and tau masses. Both boundary conditions have universal scalar masses and "just so" splitting for the up- and down-type Higgs masses. In these models, the third family scalars are lighter than the first two families and the gauginos are lighter than all the scalars. We therefore focus on the gluino phenomenology in these models. In particular, we estimate the lowest allowed gluino mass in our models coming from the most recent LHC data and compare this to limits obtained using simplified models. We find that the lower bound on Mg ˜ in Yukawa-unified SO(10) SUSY GUTs is generically ˜1.2 TEV at the 1? level unless there is considerable degeneracy between the gluino and the lightest supersymmetric particle, in which case the bounds are much weaker. Hence many of our benchmark points are not ruled out by the present LHC data and are still viable models which can be tested at LHC 14.

Anandakrishnan, Archana; Bryant, B. Charles; Raby, Stuart

2014-07-01

256

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

257

Monte Carlo Study of the Coulomb Interaction in Nanoscale Silicon Devices

NASA Astrophysics Data System (ADS)

Three-dimensional Monte Carlo simulations coupled self-consistently with the Poisson equation are carried out under the double-gate metal-oxide-semiconductor field-effect-transistor (MOSFET) structures with various channel lengths. The Coulomb force experienced by an electron inside the device is directly evaluated by performing the Monte Carlo simulations with or without the full Coulomb interaction and the plasmon excitation represented by dynamical potential fluctuations in the source and drain regions by the channel electrons is demonstrated. The drain current and transconductance are greatly degraded below the channel length of 20 nm if the self-consistent potential fluctuations are taken into account and, thus, the Coulomb interaction is indeed a key ingredient for reliable predictions of device properties.

Sano, Nobuyuki

2011-01-01

258

NASA Astrophysics Data System (ADS)

Utilizing the integral expression of Coulomb's Law to determine the electric potential from a continuous charge distribution is a canonical exercise in Electricity and Magnetism (E&M). In this study, we use both think-aloud interviews and responses to traditional exam questions to investigate student difficulties with this topic at the upper-division level. Leveraging a theoretical framework for the use of mathematics in physics, we discuss how students activate, construct, execute and reflect on the integral form of Coulomb's Law when solving problems with continuous charge distributions. We present evidence that junior-level E&M students have difficulty mapping physical systems onto the mathematical expression for the Coulomb potential. Common challenges include difficulty expressing the difference vector in appropriate coordinates as well as determining expressions for the differential charge element and limits of integration for a specific charge distribution. We discuss possible implications of these findings for future research directions and instructional strategies.

Wilcox, Bethany R.; Caballero, Marcos D.; Pepper, Rachel E.; Pollock, Steven J.

2013-01-01

259

Coulomb wave functions in momentum space

NASA Astrophysics Data System (ADS)

An algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space is presented. The arguments are the Sommerfeld parameter ?, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p ? q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of | ? | in the range of 10-1 to 10, and thus is particularly suited for momentum space calculations of nuclear reactions.

Eremenko, V.; Upadhyay, N. J.; Thompson, I. J.; Elster, Ch.; Nunes, F. M.; Arbanas, G.; Escher, J. E.; Hlophe, L.

2015-02-01

260

Coulomb Force as an Entropic Force

Motivated by Verlinde's theory of entropic gravity, we give a tentative explanation to Coulomb's law with an entropic force. When trying to do this, we find the equipartition rule should be extended to charges and the concept of temperature should be reinterpreted. If one accepts the holographic principle as well as our generalizations and reinterpretations, then Coulomb's law, the Poisson equation and the Maxwell equations can be derived smoothly. Our attempt can be regarded as a new way to unify the electromagnetic force with gravity, from the entropic origin. Possibly some of our postulates are related to the D-brane picture of black hole thermodynamics.

Tower Wang

2010-05-17

261

Ultraviolet Properties of the Spinless, One-Particle Yukawa Model

NASA Astrophysics Data System (ADS)

We consider the one-particle sector of the spinless Yukawa model, which describes the interaction of a nucleon with a real field of scalar massive bosons (neutral mesons). The nucleon as well as the mesons have relativistic dispersion relations. In this model we study the dependence of the nucleon mass shell on the ultraviolet cut-off . For any finite ultraviolet cut-off the nucleon one-particle states are constructed in a bounded region of the energy-momentum space. We identify the dependence of the ground state energy on and the coupling constant. More importantly, we show that the model considered here becomes essentially trivial in the limit regardless of any (nucleon) mass and self-energy renormalization. Our results hold in the small coupling regime.

Deckert, D.-A.; Pizzo, A.

2014-05-01

262

Early LHC phenomenology of Yukawa-bound heavy QQ mesons

Current limits from the LHC on fourth generation quarks are already at the unitarity bound of 500 GeV or so. If they exist, the strong Yukawa couplings are turning nonperturbative, and may form bound states. We study the domain of m{sub b'} and m{sub t'} in the range of 500 to 700 GeV, where we expect binding energies are mainly of Yukawa origin, with QCD subdominant. To be consistent with electroweak precision tests, the t' and b' quarks have to be nearly degenerate, exhibiting a new 'isospin'. Comparing relativistic expansion with a relativistic bound state approach, we find the most interesting is the production of a color octet, isosinglet vector meson (a 'gluon-prime') via qq-bar{yields}{omega}{sub 8}. Leading decay modes are {pi}{sub 8}{sup {+-}}W{sup {+-}}, {pi}{sub 8}{sup 0}Z{sup 0}, and constituent quark decay, with qq and tt-bar' and bb' subdominant. The color octet, isovector pseudoscalar {pi}{sub 8} meson decays via constituent quark decay, or to Wg. These decay rates are parameterized by the decay constant, the binding energy and mass differences, and V{sub tb'}. For small V{sub t'b}, one could have a spectacular signal of WWg, where a soft W accompanies a very massive Wg pair. In general, however, one has high multiplicity signals with b, W, and t jet substructures that are not so different from the t't-bar' and b'b-bar' search.

Enkhbat, Tsedenbaljir [Department of Physics, National Taiwan University, Taipei, Taiwan 10617 (China); Hou, Wei-Shu; Yokoya, Hiroshi [Department of Physics, National Taiwan University, Taipei, Taiwan 10617 (China); National Center for Theoretical Sciences, National Taiwan University, Taipei, Taiwan 10617 (China)

2011-11-01

263

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 (? _min^G=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

264

GUT predictions for quark-lepton Yukawa coupling ratios with messenger masses from non-singlets

NASA Astrophysics Data System (ADS)

We propose new predictions from grand unified theories (GUTs) [applicable to both supersymmetric (SUSY) and non-SUSY models] for the ratios of quark and lepton Yukawa couplings. These new predictions arise from splitting the masses of the messenger fields for the GUT-scale Yukawa operators by Clebsch-Gordan factors from GUT symmetry breaking. This has the effect that these factors enter inversely in the predicted quark-lepton Yukawa coupling ratios, leading to new possible GUT predictions. We systematically construct the new predictions that can be realized in this way in SU(5) GUTs and Pati-Salam unified theories and discuss model building applications.

Antusch, Stefan; King, Stephen F.; Spinrath, Martin

2014-03-01

265

The quantum mechanical two-Coulomb-centre problem in the Dirac equation framework in 2+1 dimensions

. With the help of perturbation theory the asymptotic\\u000a expansions (at small and large internuclear distances R) of the\\u000a eigenvalues (potential curves) E(R) of the two-Coulomb-centre\\u000a problem in 2+1 dimensions are obtained. We compare the results\\u000a obtained with the data from similar approximation for\\u000a two-Coulomb-centre problem in 3+1 dimensions.

V. V. Bondarchuk; I. M. Shvab

2007-01-01

266

Stretched exponential relaxation in the Coulomb glass

NASA Astrophysics Data System (ADS)

The relaxation of the specific heat and the entropy to their equilibrium values is investigated numerically for the three-dimensional Coulomb glass at very low temperatures. The long time relaxation follows a stretched exponential function, f (t) = f0exp - (t/?)? , with the exponent ? increasing with the temperature. The relaxation time diverges as an Arrhenius law when T--> 0.

Díaz-Sánchez, A.; Pérez-Garrido, A.

2001-12-01

267

Coulomb Drag in Multiwall Carbon Nanotubes

Coulomb Drag in Multiwall Carbon Nanotubes Master Thesis in Physics Anders Mathias Lunde Niels Bohr Flensberg (at the Niels Bohr int., Copenhagen University). I will like to thank my supervisors . . . . . . . . . . . . . . . . . . . 52 3.3.1 The model of the coupled Boltzmann equati

NygÃ¥rd, Jesper

268

On non-equivalence of Lorentz and Coulomb gauges within classical electrodynamics

It is shown that the well-known procedure for proving the equivalence of the expressions for the electric field calculated using the Lorentz and Coulomb gauges is incorrect. The difference between the two gauges is due to the difference in the speed of propagation of a disturbance of the scalar potential. As an auxiliary result, it is proven that the solution

Vladimir V. Onoochin

2001-01-01

269

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

270

Tunable Coulomb blockade and giant Coulomb blockade magnetoresistance in a double quantum dot array

We propose a Hubbard model to illuminate the tunneling effect of electrons in a double quantum dot array connected in the parallel circuit configuration to electrodes. The change in the interdot coupling is shown to dramatically influence the Coulomb blockade properties, consistent with earlier experimental observations. For magnetic double dots, the interdot coupling can be tuned by the external magnetic field, leading to a giant Coulomb blockade magnetoresistance.

Zhang, Xiaoguang [ORNL; Xiang, T. [Chinese Academy of Sciences

2011-01-01

271

Coulomb distortion of relativistic electrons in the nuclear electrostatic field

Continuum states of the Dirac equation are calculated numerically for the electrostatic field generated by the charge distribution of an atomic nucleus. The behavior of the wave functions of an incoming electron with a given asymptotic momentum in the nuclear region is discussed in detail and the results are compared to different approximations used in the data analysis for quasielastic electron scattering off medium and highly charged nuclei. It is found that most of the approximations provide an accurate description of the electron wave functions in the range of electron energies above 100 MeV typically used in experiments for quasielastic electron scattering off nuclei only near the center of the nucleus. It is therefore necessary that the properties of exact wave functions are investigated in detail in order to obtain reliable results in the data analysis of quasielastic (e,e'p) knockout reactions or inclusive quasielastic (e,e') scattering. Detailed arguments are given that the effective momentum approximation with a fitted potential parameter is a viable method for a simplified treatment of Coulomb corrections for certain kinematical regions used in experiments. Numerical calculations performed within the framework of the single particle shell model for nucleons lead to the conclusion that our results are incompatible with calculations performed about a decade ago, where exact electron wave functions were used in order to calculate Coulomb corrections in distorted wave Born approximation. A discussion of the exact solutions of the Dirac equation for free electrons in a Coulomb field generated by a point-like charge and some details relevant for the numerical calculations are given in the appendix.

Andreas Aste; Cyrill von Arx; Dirk Trautmann

2005-02-23

272

Coulomb drag in high Landau levels I. V. Gornyi,1,

Coulomb drag in high Landau levels I. V. Gornyi,1, * A. D. Mirlin,1,2, and F. von Oppen3,4 1 December 2004) Recent experiments on Coulomb drag in the quantum Hall regime have yielded a number of surprises. The most striking observations are that the Coulomb drag can become negative in high Landau

von Oppen, Felix

273

Established pseudo solution of second-order Dirac-Coulomb equation with position-dependent mass

We show that one of exact solutions of the second-order Dirac-Coulomb equation were pseudo. In the corresponding original literature, it was considered that the mass of the electron with a Coulomb potential was position-dependent, but the obtained eigenvalues set was not the inevitable mathematical deduction of the given second-order Dirac equation, and the second-order Dirac equations were not the inevitable mathematical deduction of the given couplet first-order Dirac equation with the position-dependent mass of the electron. In the present paper, we obtain the correct solution of the introduced first-order differential equations. This new solution would be tenable only when the wave equation is correct, but there is not any experiment date to validate the so-called position-dependent of the electron in the Coulomb field.

Ruida Chen

2007-06-28

274

Semiclassical wave functions and semiclassical dynamics for the Kepler/Coulomb problem

NASA Astrophysics Data System (ADS)

We investigate the semiclassical Kepler/Coulomb problem using the classical constants of the motion in the framework of Nelson’s stochastic mechanics. This is done by considering the eigenvalue relations for a family of coherent states (known as the atomic elliptic states) whose wave functions are concentrated on the elliptical orbit corresponding to the associated classical problem. We show that these eigenvalue relations lead to identities for the semiclassical energy, angular momentum and Hamilton-Lenz-Runge vectors in the elliptical case. These identities are then extended to include the cases of circular, parabolic and hyperbolic motions. We show that in all cases the semiclassical wave function is determined by our identities and so our identities can be seen as defining a semiclassical Kepler/Coulomb problem. The results are interpreted in terms of two dynamical systems: one a complex valued solution to the classical mechanics for a Coulomb potential and the other the drift field for a semiclassical Nelson diffusion.

Neate, Andrew; Truman, Aubrey

2014-06-01

275

Yukawa structure from U(1) fluxes in F-theory Grand unification

In F-theory GUT constructions Yukawa couplings necessarily take place at the intersection of three matter curves. For generic geometric configurations this gives rise to problematic Yukawa couplings unable to reproduce the observed hierarchies. We point out that if the U(1)B-L\\/U(1)Y flux breaking the SO(10)\\/SU(5) GUT symmetry is allowed to go through pairs of matter curves with the same GUT representation,

L. E. Ibáñez

2009-01-01

276

CP invariance of chiral gauge theories and Majorana-Yukawa couplings on the lattice

The construction of CP-invariant lattice chiral gauge theories and the construction of lattice Majorana fermions with chiral Yukawa couplings is subject to topological obstructions. In the present work we suggest lattice extensions of charge and parity transformation for Weyl fermions. This enables us to construct lattice chiral gauge theories that are CP invariant. For the construction of Majorana-Yukawa couplings, we discuss two models with symplectic Majorana fermions: a model with two symplectic doublets, and one with an auxiliary doublet.

Yuji Igarashi; Jan M. Pawlowski

2009-11-11

277

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

278

NASA Astrophysics Data System (ADS)

We present four new quark-quark potentials, developed in the framework of the nonrelativistic quark model (NRQM), which can reproduce quite well the spectra of mesons and baryons. They contain a central part which is of type “Coulomb+linear” or “Coulomb +2/3-power”, and a strong but smooth hyperfine term. With these four potentials and the one proposed by Bhaduri et al., we have calculated masses and decay properties of some interesting diquonia ( q 2 q -2 mesons). We have not found appreciable difference between the results of the five potentials considered, indicating that the properties of diquonia are, to a large extent, potential-independent in the NRQM.

Semay, C.; Silvestre-Brac, B.

1994-06-01

279

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

280

Coulomb drag from spinon-holon coupling

NASA Astrophysics Data System (ADS)

We discuss the density and temperature dependence of the Coulomb drag resistivity due to long-wavelength scattering between quantum wires, based on an approximation for the dynamic charge response of nonlinear spin-1/2 Luttinger liquids. Besides accounting for the broadening of the charge peak in the dynamic charge response due to two-holon excitations, the nonlinearity of the dispersion gives rise to a two-spinon peak, which at zero temperature has an asymmetric line shape. When the charge velocity of one wire matches the spin velocity of the other wire, the drag resistivity is enhanced by holon-spinon scattering, and its temperature dependence has signatures of spin diffusion. This effect opens the possibility of observing spin-charge separation in Coulomb drag experiments.

Pereira, Rodrigo; Sela, Eran

2010-03-01

281

The one dimensional Coulomb lattice fluid capacitor

The one dimensional Coulomb lattice fluid in a capacitor configuration is studied. The model is formally exactly soluble via a transfer operator method within a field theoretic representation of the model. The only interactions present in the model are the one dimensional Coulomb interaction between cations and anions and the steric interaction imposed by restricting the maximal occupancy at any lattice site to one particle. Despite the simplicity of the model, a wide range of intriguing physical phenomena arise, some of which are strongly reminiscent of those seen in experiments and numerical simulations of three dimensional ionic liquid based capacitors. Notably we find regimes where over-screening and density oscillations are seen near the capacitor plates. The capacitance is also shown to exhibit strong oscillations as a function of applied voltage. It is also shown that the corresponding mean field theory misses most of these effects. The analytical results are confirmed by extensive numerical simulations.

Vincent Demery; David S. Dean; Thomas C. Hammant; Ronald R. Horgan; Rudolf Podgornik

2012-06-21

282

The overcritical Dirac-Coulomb operator

NASA Astrophysics Data System (ADS)

Considering relativistic hydrogenic systems with one electron moving around a fixed nuclear centre of charge Ze0/?, we analyse the corresponding Dirac-Coulomb operator; our focus here lies on the Z-regime in which this operator is no longer essentially self-adjoint but allows various self-adjoint extensions. We characterize these self-adjoint extensions by appropriate boundary conditions at the nuclear centre and study their spectral as well as other relevant properties. A new phenomenon that can be described as ‘Rydberg doubling’ is encountered in the overcritical regime Z > 1, namely for all self-adjoint extensions of the Dirac-Coulomb Hamiltonian a second Rydberg series converging to the threshold of the negative continuous spectrum emerges. The occurrence of this effect also sheds some new light on the frequently discussed problem of the ‘charged vacuum’.

Hogreve, H.

2013-01-01

283

COULOMB EFFECTS IN RELATIVISTIC NUCLEAR COLLISIONS

We derive simple analytical formulas for Coulomb final state interactions and apply them to the analysis of recent data on nuclear collisions. The {pi}{sup -}/{pi}{sup +} ratio, the {pi}{sup +} inclusive cross section, and the n/p ratio are studied. A relativistic field theoretic model is used to derive the formulas to first order in Z{alpha}. Then, based on certain well known non-perturbative results, we recast those formulas in an approximate non-perturbative form to increase their domain of applicability and remove unphysical singularities arising from perturbation theory. The final formulas are covariant and take into account multiple independently moving charged fragments of finite size and finite thermal expansion velocities. Our studies demonstrate analytically the complexity and importance of Coulomb distortions in nuclear collisions.

Gyulassy, M.; Kaufmann, S.K.

1980-03-01

284

Fermionic dark matter with pseudo-scalar Yukawa interaction

NASA Astrophysics Data System (ADS)

We consider a renormalizable extension of the standard model whose fermionic dark matter (DM) candidate interacts with a real singlet pseudo-scalar via a pseudo-scalar Yukawa term while we assume that the full Lagrangian is CP-conserved in the classical level. When the pseudo-scalar boson develops a non-zero vacuum expectation value, spontaneous CP-violation occurs and this provides a CP-violated interaction of the dark sector with the SM particles through mixing between the Higgs-like boson and the SM-like Higgs boson. This scenario suggests a minimal number of free parameters. Focusing mainly on the indirect detection observables, we calculate the dark matter annihilation cross section and then compute the DM relic density in the range up to mDM = 300 GeV.We then find viable regions in the parameter space constrained by the observed DM relic abundance as well as invisible Higgs decay width in the light of 125 GeV Higgs discovery at the LHC. We find that within the constrained region of the parameter space, there exists a model with dark matter mass mDM ~ 38 GeV annihilating predominantly into b quarks, which can explain the Fermi-LAT galactic gamma-ray excess.

Ghorbani, Karim

2015-01-01

285

Coulomb effects in semiconductor quantum dots

Coulomb correlations in the optical spectra of semiconductor quantum dots are investigated using a full-diagonalization approach. The resulting multi-exciton spectra are discussed in terms of the symmetry of the involved states. Characteristic features of the spectra like the nearly equidistantly spaced s-shell emission lines and the approximately constant p-shell transition energies are explained using simplified Hamiltonians that are derived taking

Norman Baer; Paul Gartner; Frank Jahnke

2004-01-01

286

Coulomb sum rule in the quasielastic region

Within a relativistic single particle model, we calculate the Coulomb sum\\u000arule of inclusive electron scattering from $^{40}$Ca and $^{208}$Pb in\\u000aquasielastic region. Theoretical longitudinal and transverse structure\\u000afunctions are extracted for three momentum transfers from 300 to 500 MeV\\/c and\\u000acompared with the experimental data measured at Bates and Saclay. We find that\\u000athere is no drastic suppression of

K. S. Kim; B. G. Yu; M. K. Cheoun

2006-01-01

287

PEPC: Pretty Efficient Parallel Coulomb-solver

Abstract: An parallel tree code for rapid computation of long-range Coulomb forces based on the Warren-Salmon`Hashed Oct Tree' algorithm is described. Communication overhead is minimised by bundling multipoledata for large groups of particles prior to shipment. Implementations on the Cray T3E and the IBM-p690cluster show the expected O(N log N) scaling with particle number, as well as good scaling properties

Paul Gibbon

2003-01-01

288

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

289

Exciton condensation and perfect Coulomb drag.

Coulomb drag is a process whereby the repulsive interactions between electrons in spatially separated conductors enable a current flowing in one of the conductors to induce a voltage drop in the other. If the second conductor is part of a closed circuit, a net current will flow in that circuit. The drag current is typically much smaller than the drive current owing to the heavy screening of the Coulomb interaction. There are, however, rare situations in which strong electronic correlations exist between the two conductors. For example, double quantum well systems can support exciton condensates, which consist of electrons in one well tightly bound to holes in the other. 'Perfect' drag is therefore expected; a steady transport current of electrons driven through one quantum well should be accompanied by an equal current of holes in the other. Here we demonstrate this effect, taking care to ensure that the electron-hole pairs dominate the transport and that tunnelling of charge between the quantum wells, which can readily compromise drag measurements, is negligible. We note that, from an electrical engineering perspective, perfect Coulomb drag is analogous to an electrical transformer that functions at zero frequency. PMID:22914164

Nandi, D; Finck, A D K; Eisenstein, J P; Pfeiffer, L N; West, K W

2012-08-23

290

Long Range Potential Component in the NN Force

NASA Astrophysics Data System (ADS)

The Fourier transform of the Born term of the AGS equation in the NN ?-system generates an energy-dependent Yukawa-type local NN-quasi-potential. An appropriate average with respect to energy suggests a variety of local NN-potentials with different ranges: 1/ r( r + a) m-1 (for 2 ? m) where in the long range region it becomes 1/ r m , while in the short range region the Yukawa-type potential e -( m-1) r/ a / r results. Therefore, one finds that the Yukawa potential is automatically accompanied by an additional longer range interaction 1/ r m . For m = 2, the potential 1/ r 2 produces Efimov-like bound states in the deuteron spectra. The m = 6, 7 cases lead to the Van der Waals potential.

Oryu, Shinsho

2013-03-01

291

Finsler-type modification of the Coulomb law

NASA Astrophysics Data System (ADS)

Finsler geometry is a natural generalization of pseudo-Riemannian geometry. It can be motivated e.g. by a modified version of the Ehlers-Pirani-Schild axiomatic approach to space-time theory. Also, some scenarios of quantum gravity suggest a modified dispersion relation which could be phrased in terms of Finsler geometry. On a Finslerian space-time, the universality of free fall is still satisfied but local Lorentz invariance is violated in a way not covered by standard Lorentz invariance violation schemes. In this paper we consider a Finslerian modification of Maxwell's equations. The corrections to the Coulomb potential and to the hydrogen energy levels are computed. We find that the Finsler metric corrections yield a splitting of the energy levels. Experimental data provide bounds for the Finsler parameters.

Itin, Yakov; Lämmerzahl, Claus; Perlick, Volker

2014-12-01

292

Strong nuclear couplings as a source of Coulomb rainbow suppression

A recent measurement of the {sup 11}Be+{sup 64}Zn quasielastic scattering angular distribution exhibits a non-Fresnel-type pattern, in contrast to {sup 6}He+{sup 64}Zn elastic scattering but similar to that for the elastic scattering of {sup 6}He from heavy targets. We show by means of continuum discretized coupled-channels (CDCC) calculations that this unusual behavior of {sup 11}Be is caused by the much greater importance of nuclear coupling to the continuum in {sup 11}Be compared to {sup 6}He, 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. [Department of Nuclear Reactions, The Andrzej Soltan Institute for Nuclear Studies, ul. Hoza 69, PL-00-681 Warsaw (Poland); Alamanos, N. [CEA Saclay DSM/IRFU/DIR, F-91 191 Gif-sur-Yvette Cedex (France); Kemper, K. W. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States); Rusek, K. [Heavy Ion Laboratory, University of Warsaw, ul. Pasteura 5A, PL-02-093 Warsaw (Poland); Department of Nuclear Reactions, The Andrzej Soltan Institute for Nuclear Studies, ul. Hoza 69, PL-00-681 Warsaw (Poland)

2010-09-15

293

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

294

Structure of multi-component/multi-Yukawa mixtures

NASA Astrophysics Data System (ADS)

Recent small angle scattering experiments reveal new peaks in the structure function S(k) of colloidal systems (Liu et al 2005 J. Chem. Phys. 122 044507), in a region that was inaccessible with older instruments. It has been increasingly evident that a single (or double) Yukawa MSA-closure cannot account for these observations, and three or more terms are needed. On the other hand the MSA is not sufficiently accurate (Broccio et al 2005 Preprint); more accurate theories such as the HNC have been tried. But while the MSA is asymptotically exact at high densities (Rosenfield and Blum 1986 J. Chem. Phys. 85 1556), it does not satisfy the low density asymptotics. This has been corrected in the soft MSA (Blum et al 1972 J. Chem. Phys. 56 5197, Narten et al 1974 J. Chem. Phys. 60 3378) by adding exponential type terms. The results compared to experiment and simulation for liquid sodium by Rahman and Paskin (as shown in Blum et al 1972 J. Chem. Phys. 56 5197) are remarkably good. We use here a general closure of the Ornstein-Zernike equation, which is not necessarily the MSA closure (Blum and Hernando 2001 Condensed Matter Theories vol 16 ed Hernandez and Clark (New York: Nova) p 411). \\begin{equation} \\fl c_{ij}(r)=\\sum_{n=1}^{M}{\\cal{K}}_{ij}^{(n)}\\rme^{-z_{n}r}/r\\tqs {\\cal{K}}_{ij}^{(n)}=K^{(n)}\\delta_{i}^{(n)}\\delta_{j}^{(n)}\\tqs r\\geq \\sigma_{ij} \\label{eq1} \\end{equation} with the boundary condition for gij(r) = 0 for r<=?ij. This general closure of the Ornstein-Zernike equation will go well beyond the MSA since it has been tested by Monte Carlo simulation for tetrahedral water (Blum et al 1999 Physica A 265 396), toroidal ion channels (Enriquez and Blum 2005 Mol. Phys. 103 3201) and polyelectrolytes (Blum and Bernard 2004 Proc. Int. School of Physics Enrico Fermi, Course CLV vol 155, ed Mallamace and Stanley (Amsterdam: IOS Press) p 335). For this closure we get for the Laplace transform of the pair correlation function an explicitly symmetric result \\begin{equation} \\fl 2 \\pi \\tilde{g}_{ij}(s)=-\\frac{\\rme^{-s \\sigma_{ij}}}{D_{\\tau}(s)} \\left\\{{1\\over s^2}+{1\\over s}Q^{\\prime}_{ij}(\\sigma_{ij})+\\sum_{m=1}^{M}{{ z_m \\tilde{\\cal{X}}}_i^{(m)}{f}_j^{(m)}\\over{s+z_m}}\\right\\}. \\label{eq2} \\end{equation} This function is also easily transformed into S(k) by replacing s\\Rightarrow \\rmi k . For low density situations (dilute colloids) D_{\\tau } (s)\\sim 1+{\\cal {O}(\\rho)} and S(k) is a sum of M Lorentzians. For hard sphere PY mixtures we get the simple (compare Lebowitz 1964 Phys. Rev. 133 A895 and Blum and Stell 1979 J. Chem. Phys. 71 42) \\[ 2 \\pi \\tilde{g}_{ij}(s)=-\\frac{\\rme^{-s \\sigma_{ij}}}{s^2 D_{\\tau}(s)} \\left\\{1+s\\left[(Q^{HS})^{\\prime}_{ij}(\\sigma_{ij})\\right]\\right\\} \\] where D?(s) is a scalar function. For polydisperse electrolytes in the MSA a simpler expression is also obtained (compare Blum and Hoye 1977 J. Phys. Chem. 81 1311). An explicit continued fraction solution of the one component multi-Yukawa case is also given.

Blum, L.; Arias, M.

2006-09-01

295

Diffusive currents and Coulomb separation of ions in dense matter

NASA Astrophysics Data System (ADS)

We derive diffusive currents in strongly coupled Coulomb ion mixtures in dense stellar matter. Coulomb coupling in the presence of gravity and electric fields, induced by gravity owing to plasma polarization, creates a specific diffusion current which separates ions with the same A/Z (mass to charge number ratios) but different Z. This Coulomb separation can be important in white dwarfs and neutron stars.

Beznogov, M. V.; Yakovlev, D. G.

2014-12-01

296

Mathematical structure of relativistic Coulomb integrals

We show that the diagonal matrix elements

Suslov, Sergei K. [School of Mathematical and Statistical Sciences and Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, Arizona 85287-1804 (United States)

2010-03-15

297

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

298

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

299

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

300

Coulombic dragging of molecular assemblies on nanotubes

NASA Astrophysics Data System (ADS)

We show by molecular dynamics simulations that polar molecules, ions and their assemblies could be Coulombically dragged on the surfaces of single-wall carbon and boron-nitride nanotubes by ionic solutions or individual ions moving inside the nanotubes [1,2]. We also briefly discuss highly selective ionic sieves based on graphene monolayers with nanopores [3]. These phenomena could be applied in molecular delivery, separation and desalination.[3pt] [1] Boyang Wang and Petr Kral, JACS 128, 15984 (2006). [0pt] [2] Boyang Wang and Petr Kral, Phys. Rev. Lett. 101, 046103 (2008). [0pt] [3] Kyaw Sint, Boyang Wang and Petr Kral, JACS, ASAP (2008).

Kral, Petr; Sint, Kyaw; Wang, Boyang

2009-03-01

301

Intermediate Energy Coulomb Excitation of Neutron-Rich Nuclei

NASA Astrophysics Data System (ADS)

We reinvestigate the collective effects of the retardation as well as the bending on the Coulomb excitation cross sections and also on the B(E2) strengths of some neutron-rich isotopes using the intermediate energy Coulomb excitation theory. It is found that the B(E2) strengths extracted from the experimental Coulomb excitation cross section data get suppressed approximately by 6%. Furthermore, the obtained B(E2) strengths in the energy range 30-100 MeV/A are found to be in better agreement with the corresponding values known from other sources, than those obtained by using the recoil-corrected relativistic Coulomb excitation theory.

Rajiv, Kumar; Rajesh, Kharab; Sharma C., H.

2010-03-01

302

Approximate 3-body Coulomb corrections for HBT interferometry

We have used solutions to the quantum continuum 3-body Coulomb problem in the limits of high and low relative momentum to examine {open_quotes}candidate{close_quotes} corrections for Coulomb interactions in three pion Hanbury-Brown-Twiss interferometry. We suggest this new form of 3-body Coulomb where G({eta}{sub ij}) is a Gamow penetrability, {eta}{sub ij} is the Sommerfeld parameter, and C is an arbitrary constant assigned a value of 1.0. We compare this form with Monte Carlo calculations of 3-particle correlation functions using approximate symmetrized 3-particle Coulomb wave functions.

Cramer, J.G.; Efimov, V.; Sacksteder, V.E. IV

1993-10-01

303

Techniques for heavy-ion coupled-channels calculations. I. Long-range Coulomb coupling

NASA Astrophysics Data System (ADS)

Direct-reaction calculations for heavy ions require special computational techniques that take advantage of the physical peculiarities of heavy-ion systems. This paper is the first of a series on quantum-mechanical coupled-channels calculations for heavy ions. It deals with the problems posed by the long range of the Coulomb coupling interaction. Our approach is to use the Alder-Pauli factorization whereby the channel wave functions are expressed as products of Coulomb functions and modulating amplitudes. The equations for the modulating amplitudes are used to integrate inwards from infinity to a nuclear matching radius (~ 20 fm). To adequate accuracy, the equations for the amplitudes can be reduced to first order and solved in first Born approximation. The use of the Born approximation leads to rapid recursion relations for the solutions of the Alder-Pauli equations and hence to a great reduction in computational labor. The resulting coupled-channels Coulomb functions can then be matched in the usual way to solutions of the coupled radial equations in the interior region of r space. Numerical studies demonstrate the reliability of the various techniques introduced. NUCLEAR REACTIONS HI coupled-channel inelastic scattering. Treatment of long-range Coulomb potential.

Rhoades-Brown, M.; Macfarlane, M. H.; Pieper, Steven C.

1980-06-01

304

Matter wave functions and Yukawa couplings in F-theory Grand Unification

We study the local structure of zero mode wave functions of chiral matter fields in F-theory unification. We solve the differential equations for the zero modes derived from local Higgsing in the 8-dimensional parent action of F-theory 7-branes. The solutions are found as expansions both in powers and derivatives of the magnetic fluxes. Yukawa couplings are given by an overlap integral of the three wave functions involved in the interaction and can be calculated analytically. We provide explicit expressions for these Yukawas to second order both in the flux and derivative expansions and discuss the effect of higher order terms. We explicitly describe the dependence of the couplings on the U(1) charges of the relevant fields, appropriately taking into account their normalization. A hierarchical Yukawa structure is naturally obtained. The application of our results to the understanding of the observed hierarchies of quarks and leptons is discussed.

A. Font; L. E. Ibanez

2009-07-28

305

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

306

Tan(beta) enhanced Yukawa couplings for supersymmetric Higgs singlets at one loop

NASA Astrophysics Data System (ADS)

Extensions of the MSSM generically feature gauge singlet Higgs bosons. These singlet Higgs bosons have tan ?-enhanced Yukawa couplings to down-type quarks and leptons at the one loop level. We present an effective Lagrangian incorporating these Yukawa couplings and use it to study their effect on singlet Higgs boson phenomenology within both the mnSSM and NMSSM. It is found that the loop-induced couplings represent an appreciable effect for the singlet pseudoscalar in particular and may dominate its decay modes in some regions of parameter space.

Hodgkinson, R. N.

2008-05-01

307

New Constraints on Yukawa-Type Interactions from the Casimir Effect

NASA Astrophysics Data System (ADS)

Measurements of the Casimir force are used to obtain stronger constraints on the parameters of hypothetical interactions predicted in different unification schemes beyond the Standard Model. We review new strong constraints on the Yukawa-type interactions derived during the last two years from recent experiments on measuring the lateral Casimir force, Casimir force in configurations with corrugated boundaries and the Casimir-Polder force. Specifically, from measurements of the lateral Casimir force compared with the exact theory the strengthening of constraints up to a factor of 24 millions was achieved. We also discuss further possibilities to strengthen constraints on the Yukawa interactions from the Casimir effect.

Mostepanenko, V. M.; Bezerra, V. B.; Klimchitskaya, G. L.; Romero, C.

2012-07-01

308

New Constraints on Yukawa-Type Interactions from the Casimir Effect

NASA Astrophysics Data System (ADS)

Measurements of the Casimir force are used to obtain stronger constraints on the parameters of hypothetical interactions predicted in different unification schemes beyond the Standard Model. We review new strong constraints on the Yukawa-type interactions derived during the last two years from recent experiments on measuring the lateral Casimir force, Casimir force in configurations with corrugated boundaries and the Casimir-Polder force. Specifically, from measurements of the lateral Casimir force compared with the exact theory the strengthening of constraints up to a factor of 24 millions was achieved. We also discuss further possibilities to strengthen constraints on the Yukawa interactions from the Casimir effect.

Mostepanenko, V. M.; Bezerra, V. B.; Klimchitskaya, G. L.; Romero, C.

2012-06-01

309

Particle simulation model of transport in a bounded, Coulomb collisional plasma

The transport of particles and energy in a fully ionized, collisional plasma is studied through the use of a kinetic transport model. A particle-in-cell (PIC) code has been coupled to a Monte Carlo, binary particle model of Coulomb collisions, to provide a fully kinetic, self-consistent description of transport and potential formation in a single spatial dimension and two velocity components

Richard J. Procassini; Charles K. Birdsall

1991-01-01

310

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

311

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

312

Comparative studies of Coulomb barrier heights for nuclear models applied to sub-barrier fusion

NASA Astrophysics Data System (ADS)

Coulomb barrier heights provided by different nuclear interaction models including the Bass model, the proximity potential model, and the double folding model have been applied for experimental data of fusion in terms of a recently proposed energy scaling approach. The results show that the proximity potential description of the barrier heights seems to be closest to the values required by the systematics. It is suggested that the proximity potential model is the most suitable model to calculate the barrier height. However, the double folding model gives the lowest barrier heights.

Qu, W. W.; Zhang, G. L.; Zhang, H. Q.; Wolski, R.

2014-12-01

313

Tabletop nucleosynthesis driven by cluster Coulomb explosion.

Coulomb explosion of completely ionized (CH4)n, (NH3)n, and (H2O)n clusters will drive tabletop nuclear reactions of protons with 12C6+, 14N7+, and 16O8+ nuclei, extending the realm of nuclear reactions driven by ultraintense laser-heterocluster interaction. The realization for nucleosynthesis in exploding cluster beams requires complete electron stripping from the clusters (at laser intensities I(M) > or = 10(19) W cm(-2)), the utilization of nanodroplets of radius 300-700 A for vertical ionization, and the attainment of the highest energies for the nuclei (i.e., approximately 30 MeV for heavy nuclei and approximately 3 MeV for protons). PMID:17155473

Last, Isidore; Jortner, Joshua

2006-10-27

314

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

315

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

316

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

317

Temperature-dependent Coulomb excitations in silicene

NASA Astrophysics Data System (ADS)

The temperature-dependent Coulomb screening and excitation spectrum of electrons in silicene are studied by the tight-binding model and the random-phase approximation. With the spin–orbit interaction, monolayer silicene is a narrow-gap semiconductor. At finite temperatures, the interplay between the intraband and interband transitions could lead to an undamped plasmon mode at low frequencies. The plasmon mode only exists in a limited region of temperature and momentum, corresponding to the constrained gap transition. Beyond that region, another damped plasmon mode dominates the excitation spectrum. The drastic change in the plasmon behavior might be observed experimentally, which could allow for the identification of the spin–orbit energy gap.

Wu, J. Y.; Chen, S. C.; Lin, M. F.

2014-12-01

318

Coulomb interaction of acceptors in Cd{sub 1?x}Mn{sub x}Te/CdTe quantum dot

The investigation on the effect of confining potential like isotropic harmonic oscillator type potential on the binding and the Coulomb interaction energy of the double acceptors in the presence of magnetic field in a Cd{sub 1?x}Mn{sub x}Te/CdTe Spherical Quantum Dot has been made for the Mn ion composition x=0.3 and compared with the results obtained from the square well type potential using variational procedure in the effective mass approximation.

Kalpana, P.; Nithiananthi, P., E-mail: kjkumar-gri@rediffmail.com; Jayakumar, K., E-mail: kjkumar-gri@rediffmail.com [Department of Physics, Gandhigram Rural University, Gandhigram-624302, TamilNadu (India); Reuben, A. Merwyn Jasper D. [Department of Physics, School of Engineering, Saveetha University, Thandalam, Chennai- 600104, TamilNadu (India)

2014-04-24

319

Infinite volume limit of the strongly coupled Yukawa/sub 2/ model

Using the FKG inequality, we construct infinite volume expectations of products of boson fields and fermi currents (u-baru)/sub ren/ for the scalar Yukawa/sub 2/ model with arbitrary coupling constant. These expectations satisfy the Osterwalder--Schrader axioms with the possible exception of clustering.

Battle, G.A.; Rosen, L.

1981-04-01

320

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

321

Yukawa coupling and anomalous magnetic moment of the muon: An update for the LHC era

We study the interplay between a soft muon Yukawa coupling generated radiatively with the trilinear A-terms of the minimal supersymmetric standard model (MSSM) and the anomalous magnetic moment of the muon. In the absence of a tree-level muon Yukawa coupling the lightest smuon mass is predicted to be in the range between 600 GeV and 2200 GeV at 2{sigma}, if the bino mass M{sub 1} is below 1 TeV. Therefore, a detection of a smuon (in conjunction with a sub-TeV bino) at the LHC would directly imply a nonzero muon Yukawa coupling in the MSSM superpotential. Inclusion of slepton flavor mixing could in principle lower the mass of one smuonlike slepton below 600 GeV. However, the experimental bounds on radiative lepton decays instead strengthen the lower mass bound, with larger effects for smaller M{sub 1}, We also extend the analysis to the electron case and find that a light selectron close to the current experimental search limit may prove the MSSM electron Yukawa coupling to be nonzero.

Crivellin, Andreas [Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany); Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, CH-3012 Bern (Switzerland); Girrbach, Jennifer; Nierste, Ulrich [Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)

2011-03-01

322

Shear viscosity and shear thinning in two-dimensional Yukawa , J. Goree2

Shear viscosity and shear thinning in two-dimensional Yukawa liquids Z. DonkÂ´o1 , J. Goree2 , P using two different nonequi- librium molecular dynamics simulation methods. Shear viscosity values.e., the viscosity diminishes with increasing shear rate. It is expected that two-dimensional dusty plasmas

Goree, John

323

Radiative corrections to the Yukawa coupling constants in two Higgs doublet models

NASA Astrophysics Data System (ADS)

We calculate one-loop corrected Yukawa coupling constants hffbar for the standard model-like Higgs boson h in two Higgs doublet models. We focus on the models with the softly-broken Z2 symmetry, which is imposed to avoid the flavor changing neutral current. Under the Z2 symmetry, there are four types of Yukawa interactions. We find that one-loop contributions from extra Higgs bosons modify the hffbar couplings to be maximally about 5% under the constraint from perturbative unitarity and vacuum stability. Our results show that the pattern of tree-level deviations by the mixing effect in each type of Yukawa couplings from the SM predictions does not change even including radiative corrections. Moreover, when the gauge couplings hVV (V=W,Z) are found to be slightly (with a percent level) different from the SM predictions, the hffbar couplings also deviate but more largely. Therefore, in such a case, not only can we determine the type of Yukawa couplings but also we can obtain information on the extra Higgs bosons by comparing the predictions with precisely measured hffbar and hVV couplings at future electron-positron colliders.

Kanemura, Shinya; Kikuchi, Mariko; Yagyu, Kei

2014-04-01

324

Top Higgs Yukawa Coupling Analysis from ttH bW-

Top Higgs Yukawa Coupling Analysis from e+ e- Â¯ttH Â¯bW- bW+Â¯bb Hajrah Tabassam1 Victoria Martin2 of this symme- try breaking, the Higgs boson, is the most probable particle to be discovered at the Large Hadron Collider (LHC). If one, or more, Higgs particles are discovered, precise measurements of all the properties

325

We consider a semiclassical asymptotics of local trace for the 3D-Schroedinger operator with self-generated magnetic field in the case when electric potential has one or several Coulomb-like singularities; it is given by Weyl expression plus (magnetic) Scott correction term with O(h^{-4/3}) error provided distance between singularities is large enough.

Ivrii, Victor

2011-01-01

326

NASA Astrophysics Data System (ADS)

A definition of the direct correlation function (DCF) is applied to monatomic fluids modeled by spherical particles with a pair potential given by a hard-core repulsion and a Yukawa attractive tail. This potential allows one to take advantage of the known analytical properties of the solution to the Ornstein--Zernike (OZ) equation for the case in which the DCF outside the repulsive core is improved by a linear combination of two Yukawa tails. Predictions for the structure factor, S(k), at low-wave factor are studied and compared with other liquid-state theories and experimental data available in the literature. It was found that the closure considered here provided very well the OZ behavior of S(k) at low-k for the near critical point and coexistence curve regions. For the interaction range considered here, one can realize the remarkably accurate divergence of S(0) at the near critical point, which is related to the fluctuation phenomena.

Nikoofard, Hossein; Amin, Amir Hossein

2013-08-01

327

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

328

Parametrization of the Paris N-N potential

In view of practical nuclear structure calculations the Paris N-N potential is parametrized in a simple analytical form. This parametrization consists of a regularized discrete superposition of Yukawa-type terms. Results for phase shifts and deuteron parameters are presented as well as nuclear matter binding energy obtained with this potential.

M. Lacombe; B. Loiseau; J. M. Richard; R. Vinh Mau; J. Côté; P. Pirès; R. de Tourreil

1980-01-01

329

Parametrization of the Paris N-N potential

In view of practical nuclear structure calculations the Paris N-N potential is parametrized in a simple analytical form. This parametrization consists of a regularized discrete superposition of Yukawa-type terms. Results for phase shifts and deuteron parameters are presented as well as nuclear matter binding energy obtained with this potential.

Lacombe, M.; Loiseau, B.; Richard, J.M.; Vinh Mau, R.; Cote, J.; Pires, P.; de Tourreil, R.

1980-03-01

330

Numerical studies of a simple Coulomb blockade model

Ross and Dr. Chin B. Su, members of my degree committee, for their support. TABLE OF CONTENTS Page I, INTRODUCTION II. THE COULOMB BLOCKADE IN TUNNELING A. The Semiclassical Approach B. The Coulomb Blockade in STM III. NUMERICAL STUDIES OF A... and the STh'I case are discussed. In Section III, we consider a simple model I' or experiments in which a. scanning tunneling microscope (STM) is used to observe the Coulomb blockade. We simplify to a one-dimensional structure with two electrons, and a...

Shao, Jianfeng

1991-01-01

331

Structural phase transitions in the systems with isotropic repulsive potentials

NASA Astrophysics Data System (ADS)

A simple analytical approach for the calculation of the phase diagram for polymorphic fcc-bcc transition in systems with isotropic repulsive potentials is proposed. A comparison of the proposed approach with the existing numerical and theoretical data is presented for Yukawa and inverse-power potentials: the emphasis is on the Yukawa model. The influence of the non-linearity (of anharmonic corrections) of the pair interaction forces on the phase-equilibrium curves for fcc-bcc and solid-liquid phase transitions is considered.

Vaulina, O. S.; Vasilieva, E. V.

2011-09-01

332

Analysis of alpha-induced reactions on $^{151}$Eu below the Coulomb barrier

Novel measurements of $(\\alpha,\\gamma)$ and $(\\alpha$,n) reaction cross sections on the target nucleus $^{151}$Eu, close to the reaction thresholds, support the setting up of recent parameters of the $\\alpha$-particle optical model potential below the Coulomb barrier. A better understanding of the $\\alpha$-particle optical potential at these energies leads to a statistical model analysis of additional partial cross sections that were formerly measured but not considered within the model analysis. On this basis we have tentatively assigned a modified $J^{\\pi}$=9$^-$ spin and parity to the 22.7-h isomer in $^{154}$Tb.

V. Avrigeanu; M. Avrigeanu

2010-12-05

333

Analysis of {alpha}-induced reactions on {sup 151}Eu below the Coulomb barrier

Novel measurements of ({alpha},{gamma}) and ({alpha},n) reaction cross sections on the target nucleus {sup 151}Eu, close to the reaction thresholds, support the choice of recently proposed parameters of the {alpha}-particle optical model potential below the Coulomb barrier. A better understanding of the {alpha}-particle optical potential at these energies leads to a statistical model analysis of additional partial cross sections that were measured but not considered within a former model analysis. On this basis we have tentatively assigned a modified J{sup {pi}}=9{sup -} spin and parity to the 22.7-h isomer in {sup 154}Tb.

Avrigeanu, V.; Avrigeanu, M. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Bucharest-Magurele (Romania)

2011-01-15

334

Coulomb gauge ghost Dyson-Schwinger equation

NASA Astrophysics Data System (ADS)

A numerical study of the ghost Dyson-Schwinger equation in Coulomb gauge is performed and solutions for the ghost propagator found. As input, lattice results for the spatial gluon propagator are used. It is shown that in order to solve completely, the equation must be supplemented by a nonperturbative 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 renormalization is shown to be largely independent of the boundary condition. The boundary condition and the pattern of the solutions can be interpreted in terms of the Gribov gauge-fixing ambiguity. The connection to the temporal gluon propagator and the infrared slavery picture of confinement is explored.

Watson, P.; Reinhardt, H.

2010-12-01

335

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

336

Coulomb energies of icosahedral h orbitals

NASA Astrophysics Data System (ADS)

Matrix elements of all two-electron and three-electron operators that are scalar with respect to the icosahedral group I have been tabulated for the icosahedral configurations hN. These operators represent the Coulomb interaction between electrons occupying h orbitals, and also the effects (to the lowest orders of perturbation theory) of configuration interaction on the levels of hN. States and operators are labelled by the irreducible representations (irreps) of the continuous groups SO(3) and SO(5) in addition to the irreps of I. An alternative scheme is introduced in which the irreps W of SO(5) are retained, but the orbital angular-momentum quantum numbers L associated with SO(3) are replaced by the irreps of the permutation groups S5 and S6, the latter corresponding to the interchanges (possibly nonfeasible) of the six fivefold axes of an icosahedron among themselves. The kaleidoscope operator K, which rotates the weight space of SO(5) by ?/2, is an element of S5 and S6, and can be used to characterize the operators. The energy matrices in the second scheme are particularly simple, the scalar or pseudoscalar nature of the operators with respect to S5 leading to block forms either on the diagonal or off the diagonal, respectively. Operators of the former kind are invariant under the K operation and, in the hypothetical absence of the pseudoscalars, would lead to every level of icosahedral type T1 being degenerate with a level of type T2.

Judd, B. R.; Lo, Edwin

1999-10-01

337

Coulomb crystals in the magnetic field.

The body-centered-cubic Coulomb crystal of ions in the presence of a uniform magnetic field is studied using the rigid electron background approximation. The phonon mode spectra are calculated for a wide range of magnetic-field strengths and for several orientations of the field in the crystal. The phonon spectra are used to calculate the phonon contribution to the crystal energy, entropy, specific heat, Debye-Waller factor of ions, and the rms ion displacements from the lattice nodes for a broad range of densities, temperatures, chemical compositions, and magnetic fields. Strong magnetic field dramatically alters the properties of quantum crystals. The phonon specific heat increases by many orders of magnitude. The ion displacements from their equilibrium positions become strongly anisotropic. The results can be relevant for dusty plasmas, ion plasmas in Penning traps, and especially for the crust of magnetars (neutron stars with superstrong magnetic fields B > or approximately equal 10(14) G ). The effect of the magnetic field on ion displacements in a strongly magnetized neutron star crust can suppress the nuclear reaction rates and make them extremely sensitive to the magnetic-field direction. PMID:19905459

Baiko, D A

2009-10-01

338

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

339

Short-time rheology and diffusion in suspensions of Yukawa-type colloidal particles

NASA Astrophysics Data System (ADS)

A comprehensive study is presented on the short-time dynamics in suspensions of charged colloidal spheres. The explored parameter space covers the major part of the fluid-state regime, with colloid concentrations extending up to the freezing transition. The particles are assumed to interact directly by a hard-core plus screened Coulomb potential, and indirectly by solvent-mediated hydrodynamic interactions. By comparison with accurate accelerated Stokesian Dynamics (ASD) simulations of the hydrodynamic function H(q), and the high-frequency viscosity ??, we investigate the accuracy of two fast and easy-to-implement analytical schemes. The first scheme, referred to as the pairwise additive (PA) scheme, uses exact two-body hydrodynamic mobility tensors. It is in good agreement with the ASD simulations of H(q) and ??, for smaller volume fractions up to about 10% and 20%, respectively. The second scheme is a hybrid method combining the virtues of the ?? scheme by Beenakker and Mazur with those of the PA scheme. It leads to predictions in good agreement with the simulation data, for all considered concentrations, combining thus precision with computational efficiency. The hybrid method is used to test the accuracy of a generalized Stokes-Einstein (GSE) relation proposed by Kholodenko and Douglas, showing its severe violation in low salinity systems. For hard spheres, however, this GSE relation applies decently well.

Heinen, Marco; Banchio, Adolfo J.; Nägele, Gerhard

2011-10-01

340

Indirect Coulomb energy for two-dimensional atoms

In this paper we provide a family of lower bounds on the indirect Coulomb energy for atomic and molecular systems in two dimensions in terms of a functional of the single particle density with gradient correction terms.

Benguria, Rafael D.; Tusek, Matej [Departamento de Fisica, P. Universidad Catolica de Chile Casilla 306, Santiago 22 (Chile)

2012-09-15

341

We investigate the origin of phenomenologically interesting small Yukawa couplings in Type I string theory. Utilising the framework of intersecting sets of D9 and orthogonal D5 branes we demonstrate the connection between extra dimensional volumes and Yukawa couplings. For example, we show that extra dimensions with inverse lengths of $10^8$ GeV can lead to $10^{-10}$ Yukawa couplings. String selection rules, arising from the D-Brane setup, impose non-trivial constraints on the set of allowed superpotentials. As a phenomenological application of these results we construct a type I string model of inflationary particle physics which involves small Yukawa couplings of order $10^{-10}$, and simultaneously solves the strong CP and $\\mu$ problem of the MSSM, via the vacuum expectation value of the inflaton field.

O. J. Eyton-Williams; S. F. King

2005-02-17

342

Mag Lab U: Charles-Augustin de Coulomb

NSDL National Science Digital Library

This is a short biography of Charles Augustin de Coulomb, the 18th-century scientist whose experiments with a torsion balance gave rise to one of the fundamental principles of electromagnetism. The biography includes a link to a Java-based simulation of Coulomb's torsion balance device. Mag Lab U is part of a large collection of web-based educational materials for K-20, developed by the National High Magnetic Field Laboratory at Florida State University.

Neaves, Shannon

2010-05-25

343

NASA Astrophysics Data System (ADS)

Hideki Yukawa, Sin-itiro Tomonaga and Shoichi Sakata pioneered nuclear and particle physics and left enduring legacies. Their friendly collaboration and severe competition laid the foundation to bring up the active postwar generation of nuclear and particle physicists in Japan. In this presentation we illustrate milestones of nuclear and particle physics in Japan from 1930's to mid-1940's which have been clarified in Yukawa Hall Archival Library, Tomonaga Memorial Room and Sakata Memorial Archival Library.

Konuma, Michiji; Bando, Masako; Gotoh, Haruyoshi; Hayakawa, Hisao; Hirata, Kohji; Ito, Kazuyuki; Ito, Kenji; Kanaya, Kazuyuki; Konagaya, Daisuke; Kugo, Taichiro; Namba, Chusei; Nishitani, Tadashi; Takaiwa, Yoshinobu; Tanabashi, Masaharu; Tanaka, Kio; Tanaka, Sho; Ukegawa, Fumihiko; Yoshikawa, Tadashi

344

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

2012-03-20

345

Remarkable coincidence for the top Yukawa coupling and an approximately massless bound state

We calculate, with several corrections, the nonrelativistic binding by Higgs exchange and gluon exchange between six top and six antitop quarks (actually replaced by left-handed b quarks from time to time). The remarkable result is that, within our calculational accuracy of the order of 14% in the top-quark Yukawa coupling g{sub t}, the experimental running top-quark Yukawa coupling g{sub t}=0.935 happens to have just that value which gives a perfect cancellation of the unbound mass=12 top-quark masses by this binding energy. In other words the bound state is massless to the accuracy of our calculation. Our calculation is in disagreement with a similar calculation by Kuchiev et al., but this deviation may be explained by a phase transition. We and Kuchiev et al. compute on different sides of this phase transition.

Froggatt, C. D. [Department of Physics and Astronomy, Glasgow University, Glasgow G61 3JX, Scotland (United Kingdom); Niels Bohr Institute, Copenhagen 2100 (Denmark); Nielsen, H. B. [Niels Bohr Institute, Copenhagen 2100 (Denmark)

2009-08-01

346

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

347

Electromagnetic and gravitational form factors in simulated QED and Yukawa model

NASA Astrophysics Data System (ADS)

The light-cone Fock state representation of composite systems has a number of remarkable properties and for systems such as hadrons they have exact representation for angular momentum, energy-momentum tensor. We investigate the electromagnetic and gravitational form factors with zero momentum transfer in Quantum Electrodynamics (QED) and Yukawa theory. To improve the convergence near the end points of x qualitatively as well as to check the consistency of the model, we differentiate the wave function w.r.t. bound state mass. We test the behavior of the anomalous gravitomagnetic moment, which follows directly from the Lorentz boost properties of the light-cone Fock representation, for the simulated model as well as the Yukawa model. We also discuss the Pauli form factor obtained from the spin-flip matrix element.

Kumar, Narinder; Dahiya, Harleen

2014-07-01

348

Probability of metastable configurations in spherical three-dimensional Yukawa crystals.

Recently the occurrence probabilities of ground and metastable states of three-dimensional Yukawa clusters with 27 and 31 particles have been analyzed in dusty plasma experiments [D. Block, Phys. Plasmas 15, 040701 (2008)]. There it was found that, in many cases, the ground state appeared substantially less frequently than excited states. Here we analyze this question theoretically by means of molecular dynamics (MD) and Monte Carlo simulations and an analytical method based on the canonical partition function. We confirm that metastable states can occur with a significantly higher probability than the ground state. The results strongly depend on the screening parameter of the Yukawa interaction and the damping coefficient used in the MD simulations. The analytical method allows one to gain insight into the mechanisms being responsible for the occurrence probabilities of metastable states in strongly correlated finite systems. PMID:18851170

Kählert, H; Ludwig, P; Baumgartner, H; Bonitz, M; Block, D; Käding, S; Melzer, A; Piel, A

2008-09-01

349

Propagation of Coulomb stress uncertainties in physics-based aftershock models

NASA Astrophysics Data System (ADS)

Stress transfer between earthquakes is recognized as a fundamental mechanism governing aftershock sequences. A common approach to relate stress changes to seismicity rate changes is the rate-and-state constitutive law developed by Dieterich: these elements are the foundation of Coulomb-rate-and-state (CRS) models. Despite the successes of Coulomb hypothesis and of the rate-and-state formulation, such models perform worse than statistical models in an operational forecasting context: one reason is that Coulomb stress is subject to large uncertainties and intrinsic spatial heterogeneity. In this study, we characterize the uncertainties in Coulomb stress inherited from different physical quantities and assess their effect on CRS models. We use a Monte Carlo method and focus on the following aspects: the existence of multiple receiver faults; the stress heterogeneity within grid cells, due to their finite size; and errors inherited from the coseismic slip model. We study two well-recorded sequences from different tectonic settings: the Mw = 6.0 Parkfield and the Mw= 9.0 Tohoku earthquakes. We find that the existence of multiple receiver faults is the most important source of intrinsic stress heterogeneity, and CRS models perform significantly better when this variability is taken into account. The choice of slip model also generates large uncertainties. We construct an ensemble model based on published slip models and find that it outperforms individual models. Our findings highlight the importance of identifying sources of errors and quantifying confidence boundaries in the forecasts; moreover, we demonstrate that consideration of stress heterogeneity and epistemic uncertainty has the potential to improve the performance of operational forecasting models.

Cattania, Camilla; Hainzl, Sebastian; Wang, Lifeng; Roth, Frank; Enescu, Bogdan

2014-10-01

350

The crossover between an impurity band (IB) and a valence band (VB) regime as a function of the magnetic impurity concentration in a model for diluted magnetic semiconductors (DMSs) is studied systematically by taking into consideration the Coulomb attraction between the carriers and the magnetic impurities. The density of states and the ferromagnetic transition temperature of a spin-fermion model applied to DMSs are evaluated using dynamical mean-field theory and Monte Carlo (MC) calculations. It is shown that the addition of a square-well-like attractive potential can generate an IB at small enough Mn doping x for values of the p-d exchange J that are not strong enough to generate one by themselves. We observe that the IB merges with the VB when x>=xc where xc is a function of J and the Coulomb strength V. Using MC simulations, we demonstrate that the range of the Coulomb attraction plays an important role. While the on-site attraction, which has been used in previous numerical simulations, effectively renormalizes J for all values of x, an unphysical result, a nearest-neighbor range attraction renormalizes J only at very low dopings, i.e., until the bound holes wave functions start to overlap. Thus, our results indicate that the Coulomb attraction can be neglected to study Mn-doped GaSb, GaAs, and GaP in the relevant doping regimes, but it should be included in the case of Mn-doped GaN, which is expected to be in the IB regime.

Popescu, Florentin [Florida State University; Sen, Cengiz [Florida State University; Dagotto, Elbio R [ORNL; Moreo, Adriana [ORNL

2007-01-01

351

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

352

Top Yukawa coupling measurement with indefinite CP Higgs in e+e-?tt¯?

NASA Astrophysics Data System (ADS)

We consider the issue of the top quark Yukawa coupling measurement in a model-independent and general case with the inclusion of CP violation in the coupling. Arguably the best process to study this coupling is the associated production of the Higgs boson along with a tt¯ 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 is available in the context of the ILC—conclude that the coupling could be pinned down to about a 10% level with modest luminosity, our investigations show that the scenario could be different in the case of a more general coupling. The modified Lorentz structure resulting in a changed functional dependence of the cross section on the coupling, along with the difference in the cross section itself leads to considerable deviation in the sensitivity. Our studies of the ILC with 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. Detailed considerations of the decay distributions point to a need for a relook at the analysis strategy followed for the case of the 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 exercised in the measurement of the Yukawa couplings and the conclusions drawn from it.

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

2014-07-01

353

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

354

Molecular dynamics of Yukawa liquids in gravitation: Equilibrium, Instability and Transport

NASA Astrophysics Data System (ADS)

abstract-type="normal"> Using 2D molecular dynamics (MD) 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, acquire 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 (GK) formalism does not agree with that obtained from Einstein-Smoluchowski (ES) 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 be predominant as compared to the longitudinal mode, leading to a novel Anisotropic Solid-like Yukawa liquid (ASYL). In in-homogenous Yukawa liquids studied here, Mach cones are found to be asymmetric. When density gradient direction is set in the direction opposite to gravity, the equilibrium is shown to be unstable to Rayleigh-Taylor (RT) instabilities resulting in transport.

Charan, Harish; Ganesh, Rajaraman; Joy, Ashwin

2014-12-01

355

Threshold anomaly for the 7Be +58Ni system at near-Coulomb-barrier energies

NASA Astrophysics Data System (ADS)

By using recent fusion cross section measurements for the weakly bound system 7Be+58Ni around the Coulomb barrier, a simultaneous ?2 analysis of elastic scattering and fusion cross section data is performed. The analysis is carried out with optical polarization potentials for the fusion and direct reaction processes. That is, the nuclear polarization potential UN is split into a volume part UF which accounts for fusion reactions and a surface part UD R that is responsible for direct reactions. The parameters of fusion and direct reaction Woods-Saxon polarization potentials are determined by the analysis of the data. The presence of the threshold anomaly is investigated from the energy dependence of these polarization potentials. It is found that, contrary to other weakly bound systems, the 7Be+58Ni reaction presents the usual threshold anomaly.

Gómez Camacho, A.; Aguilera, E. F.

2014-12-01

356

Magneto-Coulomb effect in carbon nanotube quantum dots filled with magnetic nanoparticles.

Electrical transport measurements of carbon nanotubes filled with magnetic iron nanoparticles are reported. Low-temperature (40 mK) magnetoresistance measurements showed conductance hysteresis with sharp jumps at the switching fields of the nanoparticles. Depending on the gate voltage, positive or negative hysteresis was observed. The results are explained in terms of a magneto-Coulomb effect: The spin flip of the iron island at a nonzero magnetic field causes a shift of the chemical potential induced by the change of Zeeman energy; i.e., an effective charge variation is detected by the nanotube quantum dot. PMID:22107663

Datta, S; Marty, L; Cleuziou, J P; Tilmaciu, C; Soula, B; Flahaut, E; Wernsdorfer, W

2011-10-28

357

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

358

Probing Yukawian gravitational potential by numerical simulations. I. Changing N-body codes

NASA Astrophysics Data System (ADS)

In the weak field limit general relativity reduces, as is well known, to the Newtonian gravitation. Alternative theories of gravity, however, do not necessarily reduce to Newtonian gravitation; some of them, for example, reduce to Yukawa-like potentials instead of the Newtonian potential. Since the Newtonian gravitation is largely used to model with success the structures of the universe, such as for example galaxies and clusters of galaxies, a way to probe and constrain alternative theories, in the weak field limit, is to apply them to model the structures of the universe. In the present study, we consider how to probe Yukawa-like potentials using N-body numerical simulations.

Brandao, C. S. S.; de Araujo, J. C. N.

2010-04-01

359

NASA Astrophysics Data System (ADS)

Theoretical description of reactions in general, and the theory for (d,p) reactions, in particular, needs to advance into the future. Here deuteron-stripping processes off a target nucleus consisting of A nucleons are treated within the framework of the few-body integral equations theory. The generalized Faddeev equations in the Alt-Grassberger-Sandhas (AGS) form, which take into account the target excitations, with realistic optical potentials provide the most advanced and complete description of the deuteron stripping. The main problem in practical application of such equations is the screening of the Coulomb potential, which works only for light nuclei. In this paper we present a formulation of the Faddeev equations in the AGS form taking into account the target excitations with explicit inclusion of the Coulomb interaction. By projecting the (A+2)-body operators onto target states, matrix three-body integral equations are derived, which allow for the incorporation of the excited states of the target nucleons. Using the explicit equations for the partial Coulomb scattering wave functions in the momentum space we present the AGS equations in the Coulomb distorted wave representation without screening procedure. We also use the explicit expression for the off-shell two-body Coulomb scattering T matrix, which is needed to calculate the effective potentials in the AGS equations. The integrals containing the off-shell Coulomb T matrix are regularized to make the obtained equations suitable for calculations. For NN and nucleon-target nuclear interactions we assume the separable potentials what significantly simplifies solution of the AGS equations.

Mukhamedzhanov, A. M.; Eremenko, V.; Sattarov, A. I.

2012-09-01

360

High Speed Positioning System Considering Coulomb Friction and Inertia Variation

NASA Astrophysics Data System (ADS)

In a conventional positioning system, when the position error becomes small, the motor cannot obtain enough deceleration torque. Hence, the position response becomes slow. In order to overcome this problem, this paper proposed a new high speed positioning system of an AC servo-motor considering unknown coulomb friction, inertia variation and windup phenomenon. In this paper, the sum of coulomb friction load and inertia variation are estimated by disturbance observer. The proposed method always uses the maximum acceleration torque, the deceleration torque and maximum speed.

Mashimo, Tomonori; Ohishi, Kiyoshi; Dohmeki, Hideo

361

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

362

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

NASA Astrophysics Data System (ADS)

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.; Chetouani, L.

2012-06-01

363

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

364

Coulomb and dipole effects in tunneling ionization of molecules including nuclear motion

NASA Astrophysics Data System (ADS)

We study tunneling ionization in a one-dimensional three-body model of a molecule, treating both electronic and nuclear degrees of freedom exactly. In a recent paper [Phys. Rev. Lett. 111, 153003 (2013), 10.1103/PhysRevLett.111.153003] it was demonstrated using a finite-range potential that the Born-Oppenheimer approximation breaks down for fields weaker than a critical field FBO when describing tunneling ionization of molecules, but works for stronger fields. It was also demonstrated that the weak-field asymptotic theory allows for an accurate description in this weak-field limit. In the present paper, we consider a potential with a Coulomb tail and nonzero dipole moment, modeling polar molecules. Our study shows that the conclusions of the aforementioned paper also hold for this potential.

Svensmark, Jens; Tolstikhin, Oleg I.; Madsen, Lars Bojer

2015-01-01

365

Yukawa unification in SUSY SO(10) for mumuon g-2 and b->s gamma

It is shown that top-bottom-tau Yukawa unification for \\mus \\gamma. This happens for non-universal gaugino masses which are assumed to be generated by the F-term vev in a 54-dimensional representation of SO(10). The requirement of (g-2)_\\mu and b->s \\gamma being within 2\\sigma from the experimental central values, together with the correct relic abundance of neutralinos, leads to rather definite predictions for sparticle spectrum. In particular, the gluino mass is predicted to be between 500 and 700 GeV or between 900 GeV and 1.6 TeV.

Badziak, Marcin

2011-01-01

366

t ? b ? ? Yukawa unification for ? < 0 with a sub-TeV sparticle spectrum

We show compatibility with all known experimental constraints of t ? b ? ? Yukawa coupling unification in supersymmetric SU(4)\\u000a c\\u000a × SU(2)\\u000a L\\u000a × SU(2)\\u000a R\\u000a which has non-universal gaugino masses and the MSSM parameter ? g ? 2)\\u000a ?\\u000a is in good agreement with the observations. We identify benchmark points for the sparticle spectra which can be tested

Ilia Gogoladze; Rizwan Khalid; Shabbar Raza; Qaisar Shafi

2010-01-01

367

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

2014-09-30

368

Leading two-loop Yukawa corrections to the pole masses of SUSY fermions in the MSSM

NASA Astrophysics Data System (ADS)

We have calculated the leading Yukawa corrections to the chargino, neutralino and gluino pole masses in the DR scheme in the minimal supersymmetric Standard Model (MSSM) with the full set of complex parameters. We have performed a numerical analysis for a particular point in the parameter space and found typical corrections of a few tenths of a percent thus exceeding the experimental resolution as expected at the ILC. We provide a computer program which calculates two-loop pole masses for SUSY fermions with complex parameters up to O(??,Y,?Y).

Schöfbeck, R.; Eberl, H.

2008-07-01

369

Decay of a Yukawa fermion at finite temperature and applications to leptogenesis

We calculate the decay rate of a Yukawa fermion in a thermal bath using finite-temperature cutting rules and effective Green's functions according to the hard thermal loop resummation technique. We apply this result to the decay of a heavy Majorana neutrino in leptogenesis. Compared to the usual approach where thermal masses are inserted into the kinematics of final states, we find that deviations arise through two different leptonic dispersion relations. The decay rate differs from the usual approach by more than 1 order of magnitude in the temperature range which is interesting for the weak washout regime. We discuss how to arrive at consistent finite-temperature treatments of leptogenesis.

Kiessig, Clemens P.; Pluemacher, Michael [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805 Muenchen (Germany); Thoma, Markus H. [Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany)

2010-08-01

370

Wilson--Yukawa Chiral Model on Lattice and Non-commutative Geometry

Based upon the mathematical formulas of Lattice gauge theory and non-commutative geometry differential calculus, we developed an approach of generalized gauge theory on a product of the spacetime lattice and the two discrete points(or a $Z_2$ discrete group). We introduce a differentiation for non-nearest-neighbour points and find that this differentiation may lead to the introduction of Wilson term in the free fermion Lagrangian on lattice. The Wilson-Yukawa chiral model on lattice is constructed by the generalized gauge theory and a toy model and Smit-Swift model are studied.

Jianming Li; Xingchang Song; Ke Wu

1996-11-11

371

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

372

Yukawas and discrete symmetries in F-theory compactifications without section

NASA Astrophysics Data System (ADS)

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; Grimm, Thomas W.; Keitel, Jan

2014-11-01

373

Shear flows and shear viscosity in a two-dimensional Yukawa system (dusty plasma).

The shear viscosity of a two-dimensional liquid-state dusty plasma was measured experimentally. A monolayer of highly charged polymer microspheres, with a Yukawa interaction, was suspended in a plasma sheath. Two counterpropagating Ar+ laser beams pushed the particles, causing shear-induced melting of the monolayer and a shear flow in a planar Couette configuration. By fitting the particle velocity profiles in the shear flow to a Navier-Stokes model, the kinematic viscosity was calculated; it was of order 1 mm(2) s(-1), depending on the monolayer's parameters and shear stress applied. PMID:15524893

Nosenko, V; Goree, J

2004-10-01

374

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

375

Benchmark calculation for proton-deuteron elastic scattering observables including Coulomb

Two independent calculations of proton-deuteron elastic scattering observables including Coulomb repulsion between the two protons are compared in the proton lab energy region between 3 MeV and 65 MeV. The hadron dynamics is based on the purely nucleonic charge-dependent AV18 potential. Calculations are done both in coordinate space and momentum space. The coordinate-space calculations are based on a variational solution of the three-body Schr\\"odinger equation using a correlated hyperspherical expansion for the wave function. The momentum-space calculations proceed via the solution of the Alt-Grassberger-Sandhas equation using the screened Coulomb potential and the renormalization approach. Both methods agree within 1% on all observables, showing the reliability of both numerical techniques in that energy domain. At energies below three-body breakup threshold the coordinate-space method remains favored whereas at energies higher than 65 MeV the momentum-space approach seems to be more efficient.

Deltuva, A; Kievsky, A; Rosati, S; Sauer, P U; Viviani, M

2005-01-01

376

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. PMID:20366260

Khrapak, S A; Morfill, G E

2009-12-18

377

Dirac Electron in a Coulomb Field in (2+1) Dimensions

Exact solutions of Dirac equation in two spatial dimensions in the Coulomb field are obtained. Equation which determines the so-called critical charge of the Coulomb field is derived and solved for a simple model.

V. R. Khalilov; Choon-Lin Ho

1998-01-01

378

A Note on AdS/SYM Correspondence on the Coulomb Branch

We study Maldacena's conjecture and the AdS/SYM correspondence on the Coulomb branch. Several interesting aspects of this conjectured AdS/SYM correspondence on the Coulomb branch are pointed out and clarified.

Yi-Yen Wu

1998-09-18

379

Coulomb energy of uniformly-charged spheroidal shell systems

We provide exact expressions for the electrostatic energy of uniformly-charged prolate and oblate spheroidal shells. We find that uniformly-charged prolate spheroids of eccentricity greater than 0.9 have lower Coulomb energy than a sphere of the same area. For the volume-constrained case, we find that a sphere has the highest Coulomb energy among all spheroidal shells. Further, we derive the change in the Coulomb energy of a uniformly-charged shell due to small, area-conserving perturbations on the spherical shape. Our perturbation calculations show that buckling-type deformations on a sphere can lower the Coulomb energy. Finally, we consider the possibility of counterion condensation on the spheroidal shell surface. We employ a Manning-Oosawa two-state model approximation to evaluate the renormalized charge and analyze the behavior of the equilibrium free energy as a function of the shell's aspect ratio for both area-constrained and volume-constrained cases. Counterion condensation is seen to favor the forma...

Jadhao, Vikram; Thomas, Creighton K; de la Cruz, Monica Olvera

2015-01-01

380

Strong impact of protonation and deprotonation on intermolecular Coulombic decay

NASA Astrophysics Data System (ADS)

Intermolecular Coulombic decay (ICD) is an ultrafast relaxation mechanism of a highly excited system embedded in a chemical environment. Our theoretical investigation of ammonia clusters shows that the ICD efficiency can be regulated by protonation or deprotonation. It is suggested that by varying ICD rate through changing the environmental pH value a control over the relaxation dynamics can be achieved.

Kryzhevoi, Nikolai V.; Cederbaum, Lorenz S.

2012-11-01

381

Correlated continuum wave functions for three particles with Coulomb interactions

We present an approximate solution of the Schröautdinger equation for the three-body Coulomb problem. We write the Hamiltonian in parabolic curvilinear coordinates and study the possible separation of the wave equation as a system of coupled partial differential equations. When two of the particles are heavier than the others, we write an approximate wave equation that incorporates some terms of

G. Gasaneo; F. D. Colavecchia; C. R. Garibotti; J. E. Miraglia; P. Macri

1997-01-01

382

Coulomb Memory Signatures in the Excitonic Optical Stark Effect

NASA Astrophysics Data System (ADS)

Differential absorption spectra of high-quality InGaAs quantum wells are presented for various pump detunings and polarization configurations. For low intensity pump pulses tuned well below the exciton a redshift is observed for opposite circularly polarized probe pulses. Microscopic calculations show that this redshift originates from memory effects in the Coulomb-induced excitonic correlations.

Sieh, C.; Meier, T.; Jahnke, F.; Knorr, A.; Koch, S. W.; Brick, P.; Hübner, M.; Ell, C.; Prineas, J.; Khitrova, G.; Gibbs, H. M.

1999-04-01

383

Phase transitions in one-dimensional static Coulomb media

We consider configurations of $N$ charged particles on the interval with nearest neighbour Coulomb interaction and constant external force. For different values of external force we find 4 different phases of the asymptotic particle density for the configuration corresponding to the minimum of the energy.

V. A. Malyshev

2014-11-27

384

Analytic Coulomb matrix elements in a three-dimensional geometry

Using a complete basis set we have obtained an analytic expression for the matrix elements of the Coulomb interaction. These matrix elements are written in a closed form. We have used the basis set of the three-dimensional isotropic quantum harmonic oscillator in order to develop our calculations, which can be useful when treating interactions in localized systems.

Garcia, Jaime Zaratiegui [Department of Physical Sciences, P.O. Box 3000, FIN-90014 University of Oulu (Finland)

2005-12-15

385

Analytic Coulomb matrix elements in a three-dimensional geometry

Using a complete basis set we have obtained an analytic expression for the matrix elements of the Coulomb interaction. These matrix elements are written in a closed form. We have used the basis set of the three-dimensional isotropic quantum armonic oscillator in order to develop our calculations, which can be useful when treating interactions in localized systems.

Jaime Zaratiegui

2005-11-04

386

Coulomb repulsion and the electron beam directed energy weapon

NASA Astrophysics Data System (ADS)

Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into small spots at large distances from defining apertures. A classic example is the 1970s era "Star Wars" study of an electron beam directed energy weapon as an orbiting antiballistic missile device. After much analysis, it was considered physically impossible to focus a 1000-amp 1-GeV beam into a 1-cm diameter spot 1000-km from the beam generator. The main reason was that a 1-cm diameter beam would spread to 5-m diameter at 1000-km due to Coulomb repulsion. Since this could not be overcome, the idea was abandoned. But is this true? What if the rays were reversed? That is, start with a 5-m beam converging slightly with the same nonuniform angular and energy distribution as the electrons from the original problem were spreading at 1000-km distance. Could Coulomb repulsion be overcome? Looking at the terms in computational studies, some are reversible while others are not. Based on estimates, the nonreversible terms should be small - of the order of 0.1 mm. If this is true, it is possible to design a practical electron beam directed weapon not limited by Coulomb repulsion.

Retsky, Michael W.

2004-09-01

387

Calculation of bound states and resonances in perturbed Coulomb models

We calculate accurate bound states and resonances of two interesting perturbed Coulomb models by means of the Riccati-Pad\\'{e} method. This approach is based on a rational approximation to a modified logarithmic derivative of the eigenfunction and produces sequences of roots of Hankel determinants that converge towards the eigenvalues of the equation.

Francisco M. Fernandez

2007-11-19

388

Propagator for an Aharonov-Bohm-Coulomb system

The propagator of three-dimensional Aharonov-Bohm-Coulomb system is calculated by following the Duru-Kleinert method. It is shown that the system is reduced to two independent two dimensional Aharonov-Bohm plus harmonic oscillator systems through dimensional extension and Kustaanheimo-Stiefel transformation. The energy spectrum is deduced.

D. K. Park; Sahng-Kyoon Yoo; Soo-Young Lee; Jae-Rok Kahng; Chang Soo Park; Eui-Soon Yim; C. H. Lee

1997-07-02

389

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

390

Numerical simulation of heavy fermions in an SU(2)_L x SU(2)_R symmetric Yukawa model

An exploratory numerical study of the influence of heavy fermion doublets on the mass of the Higgs boson is performed in the decoupling limit of a chiral $\\rm SU(2)_L \\otimes SU(2)_R$ symmetric Yukawa model with mirror fermions. The behaviour of fermion and boson masses is investigated at infinite bare quartic coupling on $4^3 \\cdot 8$, $6^3 \\cdot 12$ and $8^3 \\cdot 16$ lattices. A first estimate of the upper bound on the renormalized quartic coupling as a function of the renormalized Yukawa-coupling is given.

C. Frick; L. Lin; I. Montvay; G. Munster; M. Plagge; T. Trappenberg; H. Wittig

1992-07-21

391

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

392

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

393

Bounding the top Yukawa coupling with Higgs-associated single-top production

NASA Astrophysics Data System (ADS)

After the discovery of the 125 GeV scalar boson with gauge properties similar to the Standard Model (SM) Higgs, the search for beyond the SM interactions will focus on studying the discovered particles' coupling properties more precisely and shedding light on the relation of fermion masses with the electroweak vacuum. The large mass of the top quark and the SM-predicted order one top Yukawa coupling is a natural candidate for beyond the SM physics, though experimentally challenging to constrain. In this paper, we argue that investigating angular correlations in pp?tHj production provides an excellent handle to constrain the top Yukawa coupling yt via direct measurements, even when we focus on rare exclusive final states. We perform a hadron-level analysis and show that we may expect to constrain yt?0.5ytSM at 95%-99% confidence level at the high luminosity LHC using semileptonic top decays and H??? alone, by employing a two-channel measurement approach.

Englert, Christoph; Re, Emanuele

2014-04-01

394

Properties of gravitationally equilibrated Yukawa systems—A molecular dynamics study

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, E-mail: ganesh@ipr.res.in; Joy, Ashwin [Institute for Plasma Research, Bhat-Village, Gujarat, Gandhinagar 382428 (India)] [Institute for Plasma Research, Bhat-Village, Gujarat, Gandhinagar 382428 (India)

2014-04-15

395

Accretionary prisms in subduction earthquake cycles: The theory of dynamic Coulomb wedge

We expand the theory of critically tapered Coulomb wedge for accretionary prisms by considering stress changes in subduction earthquake cycles. Building on the Coulomb plasticity of the classical theory, we assume an elastic-perfectly Coulomb plastic rheology and derive exact stress solutions for stable and critical wedges. The new theory postulates that the actively deforming, most seaward part of an accretionary

Kelin Wang; Yan Hu

2006-01-01

396

The driving terms in three-body theories of elastic and inelastic scattering of a charged particle off a bound state of two other charged particles contain the fully off-shell two-body Coulomb T-matrix describing the intermediate-state Coulomb scattering of the projectile with each of the charged target particles. Up to now the latter is usually replaced by the Coulomb potential, either when using the multiple-scattering approach or when solving three-body integral equations. General properties of the exact and the approximate on-shell driving terms are discussed, and the accuracy of this approximation is investigated numerically, both for atomic and nuclear processes including bound-state excitation, for energies below and above the corresponding three-body dissociation threshold, over the whole range of scattering angles.

E. O. Alt; A. S. Kadyrov; A. M. Mukhamedzhanov; M. Rauh

1995-03-16

397

NSDL National Science Digital Library

Utilizing the integral expression of Coulombâs Law to determine the electric potential from a continuous charge distribution is a canonical exercise in Electricity and Magnetism (E&M). In this study, we use both think-aloud interviews and responses to traditional exam questions to investigate student difficulties with this topic at the upper-division level. Leveraging a theoretical framework for the use of mathematics in physics, we discuss how students activate, construct, execute and reflect on the integral form of Coulombâs Law when solving problems with continuous charge distributions. We present evidence that junior-level E&M students have difficulty mapping physical systems onto the mathematical expression for the Coulomb potential. Common challenges include difficulty expressing the difference vector in appropriate coordinates as well as determining expressions for the differential charge element and limits of integration for a specific charge distribution. We discuss possible implications of these findings for future research directions and instructional strategies.

Wilcox, Bethany R.; Caballero, Marcos D.; Pepper, Rachel E.; Pollock, Steven J.

2013-07-09

398

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

399

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

400

Equal-time two-point correlation functions in Coulomb gauge Yang-Mills theory

We apply a functional perturbative approach to the calculation of the equal-time two-point correlation functions and the potential between static color charges to one-loop order in Coulomb gauge Yang-Mills theory. The functional approach proceeds through a solution of the Schroedinger equation for the vacuum wave functional to order g^2 and derives the equal-time correlation functions from a functional integral representation via new diagrammatic rules. We show that the results coincide with those obtained from the usual Lagrangian functional integral approach, extract the beta function, and determine the anomalous dimensions of the equal-time gluon and ghost two-point functions and the static potential under the assumption of multiplicative renormalizability to all orders.

D. Campagnari; A. Weber; H. Reinhardt; F. Astorga; W. Schleifenbaum

2009-10-23

401

Ion wake effects on the Coulomb ion drag in complex dusty plasmas

The ion wake effects on the Coulomb drag force are investigated in complex dusty plasmas. It is shown that the ion wake effects significantly enhance the Coulomb ion drag force. It is also found that the ion wake effects on the Coulomb drag force increase with an increase in the Debye length. In addition, the ion wake effects on the momentum transfer cross section and Coulomb drag force are found to be increased with increasing thermal Mach number, i.e., decreasing plasma temperature. It is also found that the Coulomb ion drag force would be stronger for smaller dust grains.

Ki, Dae-Han; Jung, Young-Dae [Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)

2010-09-06

402

Time-correlation functions and transport coefficients of two-dimensional Yukawa liquids Z. Donk,1,2

as compared to previous 2D Yukawa liquid simulations include an assessment of the thermal conductivity, using February 2009 The existence of coefficients for diffusion, viscosity, and thermal conductivity is examined at low temperature, but not in the opposite limits. The thermal conductivity coefficient does not appear

Goree, John

403

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

404

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.

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

2014-11-10

405

A Coulomb collision algorithm for weighted particle simulations

NASA Technical Reports Server (NTRS)

A binary Coulomb collision algorithm is developed for weighted particle simulations employing Monte Carlo techniques. Charged particles within a given spatial grid cell are pair-wise scattered, explicitly conserving momentum and implicitly conserving energy. A similar algorithm developed by Takizuka and Abe (1977) conserves momentum and energy provided the particles are unweighted (each particle representing equal fractions of the total particle density). If applied as is to simulations incorporating weighted particles, the plasma temperatures equilibrate to an incorrect temperature, as compared to theory. Using the appropriate pairing statistics, a Coulomb collision algorithm is developed for weighted particles. The algorithm conserves energy and momentum and produces the appropriate relaxation time scales as compared to theoretical predictions. Such an algorithm is necessary for future work studying self-consistent multi-species kinetic transport.

Miller, Ronald H.; Combi, Michael R.

1994-01-01

406

Silicon-based Coulomb blockade thermometer with Schottky barriers

NASA Astrophysics Data System (ADS)

A hybrid Coulomb blockade thermometer (CBT) in form of an array of intermittent aluminum and silicon islands connected in series via tunnel junctions was fabricated on a thin silicon-on-insulator (SOI) film. Tunnel barriers in the micrometer size junctions were formed by metal-semiconductor Schottky contacts between aluminium electrodes and heavily doped silicon. Differential conductance through the array vs. bias voltage was found to exhibit characteristic features of competing thermal and charging effects enabling absolute temperature measurements over the range of ˜65 to ˜500 mK. The CBT performance implying the primary nature of the thermometer demonstrated for rather trivial architecture attempted in this work paves a route for introduction of Coulomb blockade thermometry into well-developed contemporary SOI technology.

Tuboltsev, V.; Savin, A.; Rogozin, V. D.; Räisänen, J.

2014-04-01

407

Weyl Semimetal in the Strong Coulomb Interaction Limit

We study the effects of strong $1/r$ long-range Coulomb interactions in a Weyl semimetal. We consider a three-dimensional (3D) Dirac fermion system on a lattice with a time-reversal symmetry breaking term, and take into account $1/r$ long-range Coulomb interactions between the bulk electrons. This model is regarded as the case where magnetic impurities are doped into the bulk of a 3D topological insulator. With the use of the strong coupling expansion of the lattice gauge theory and the mean-field approximation, we analyze the system from the strong coupling limit. It is shown that parity symmetry of the system is spontaneously broken in the strong coupling limit, and a different type of the Weyl semimetal, in which time-reversal and parity symmetries are broken, appears in the strong coupling limit. A possible global phase diagram of a correlated Weyl semimetal is presented.

Akihiko Sekine; Kentaro Nomura

2014-07-22

408

Weyl Semimetal in the Strong Coulomb Interaction Limit

NASA Astrophysics Data System (ADS)

We study the effects of strong 1/r long-range Coulomb interactions in a Weyl semimetal. We consider a three-dimensional (3D) Dirac fermion system on a lattice with a time-reversal symmetry breaking term, and take into account 1/r long-range Coulomb interactions between the bulk electrons. This model is regarded as the case where magnetic impurities are doped into the bulk of a 3D topological insulator. With the use of the strong coupling expansion of the lattice gauge theory and the mean-field approximation, we analyze the system from the strong coupling limit. It is shown that parity symmetry of the system is spontaneously broken in the strong coupling limit, and a different type of the Weyl semimetal, in which time-reversal and parity symmetries are broken, appears in the strong coupling limit. A possible global phase diagram of a correlated Weyl semimetal is presented.

Sekine, Akihiko; Nomura, Kentaro

2014-09-01

409

Weyl Semimetal in the Strong Coulomb Interaction Limit

We theoretically study the effect of the 1/r Coulomb interaction in a Weyl semimetal. We consider a three-dimensional (3D) Dirac fermion system on a lattice with a time-reversal symmetry breaking term, and take into account the 1/r Coulomb interaction between the bulk electrons. This situation is regarded as what magnetic impurities are doped into the bulk of a 3D topological insulator. With the use of the srong coupling expansion in the lattice gauge theory, we analyze the system from the strong coupling limit. It is shown that the Weyl semimetal phase survives in the strong coupling limit. A possible global phase diagram of a correlated Weyl semimetal is presented.

Sekine, Akihiko

2013-01-01

410

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

411

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

2014-08-29

412

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

413

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

414

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

415

Atom-atom partitioning of intramolecular and intermolecular Coulomb energy

NASA Astrophysics Data System (ADS)

An atom-atom partitioning of the (super)molecular Coulomb energy is proposed on the basis of the topological partitioning of the electron density. Atom-atom contributions to the molecular intra- and intermolecular Coulomb energy are computed exactly, i.e., via a double integration over atomic basins, and by means of the spherical tensor multipole expansion, up to rank L=lA+lB+1=5. The convergence of the multipole expansion is able to reproduce the exact interaction energy with an accuracy of 0.1-2.3 kJ/mol at L=5 for atom pairs, each atom belonging to a different molecule constituting a van der Waals complex, and for nonbonded atom-atom interactions in single molecules. The atom-atom contributions do not show a significant basis set dependence (3%) provided electron correlation and polarization basis functions are included. The proposed atom-atom Coulomb interaction energy can be used both with post-Hartree-Fock wave functions and experimental charge densities in principle. The Coulomb interaction energy between two molecules in a van der Waals complex can be computed by summing the additive atom-atom contributions between the molecules. Our method is able to extract from the supermolecule wave function an estimate of the molecular interaction energy in a complex, without invoking the reference state of free noninteracting molecules. We provide computational details of this method and apply it to (C2H2)2; (HF)2; (H2O)2; butane; 1,3,5-hexatriene; acrolein and urocanic acid, thereby covering a cross section of hydrogen bonds, and covalent bonds with and without charge transfer.

Popelier, P. L. A.; Kosov, D. S.

2001-04-01

416

Coulomb Damped Relaxation Oscillations in Semiconductor Quantum Dot Lasers

We present a theoretical simulation of the turn-on dynamics of InAs\\/GaAs quantum dot semiconductor lasers driven by electrical current pulses. Our approach goes beyond standard phenomenological rate equations. It contains microscopically calculated Coulomb scattering rates, which describe Auger transitions between quantum dots and the wetting layer. In agreement with the experimental results, we predict a strong damping of relaxation oscillations

Ermin Malic; Moritz J. P. Bormann; P. Hovel; M. Kuntz; D. Bimberg; Andreas Knorr; Eckehard Scholl

2007-01-01

417

Correlated continuum wave functions for three particles with Coulomb interactions

We present an approximate solution of the Schr{umlt o}dinger equation for the three-body Coulomb problem. We write the Hamiltonian in parabolic curvilinear coordinates and study the possible separation of the wave equation as a system of coupled partial differential equations. When two of the particles are heavier than the others, we write an approximate wave equation that incorporates some terms

G. Gasaneo; F. D. Colavecchia; C. R. Garibotti; J. E. Miraglia; P. Macri

1997-01-01

418

Monte Carlo Simulation of The Adjoint Coulomb Gas

Monte Carlo simulation results for unitary matrix quantum mechanics, describing two-dimensional Yang-Mills theory coupled to a finite density of non-dynamical quarks (adjoint Coulomb gas), are presented. We characterize the deconfining transition in this model, by measuring the Polyakov Loop Susceptibility and employing finite-size scaling analysis. We provide evidence that the phase transition is first-order. Our results are consistent with the outcome of earlier large-$N$ studies of the model.

Omid Saremi

2014-12-12

419

Coulomb-gauge gluon propagator and the Gribov formula.

We analyze the lattice SU(2) Yang-Mills theory in the Coulomb gauge. We show that the static gluon propagator is multiplicative renormalizable and takes the simple form D(|p[over -->]|)(-1)=sqrt[|p[over -->]|2+M4/|p[over -->]|2], proposed by Gribov through heuristic arguments many years ago. We find M=0.88(1) GeV approximately 2sqrt[sigma]. PMID:19257344

Burgio, G; Quandt, M; Reinhardt, H

2009-01-23

420

Monte Carlo Simulation of The Adjoint Coulomb Gas

Monte Carlo simulation results for unitary matrix quantum mechanics, describing two-dimensional Yang-Mills theory coupled to a finite density of non-dynamical quarks (adjoint Coulomb gas), are presented. We characterize the deconfining transition in this model, by measuring the Polyakov Loop Susceptibility and employing finite-size scaling analysis. We provide evidence that the phase transition is first-order. Our results are consistent with the outcome of earlier large-$N$ studies of the model.

Saremi, Omid

2014-01-01

421

A Grid-Based Coulomb Collision Model for PIC Codes

A new method is presented to model the intermediate regime between collisionless and Coulomb collision dominated plasmas in particle-in-cell codes. Collisional processes between particles of different species are treated through the concept of a grid-based “collision field,” which can be particularly efficient for multi-dimensional applications. In this method, particles are scattered using a force which is determined from the moments

Michael E. Jones; Don S. Lemons; Rodney J. Mason; Vincent A. Thomas; Dan Winske

1996-01-01

422

A Dirac Particle in a Complex Potential

It has been observed that a quantum mechanical theory need not to be Hermitian to have a real spectrum. In this paper we obtain the eigenvalues of a Dirac charged particle in a complex static and spherically symmetric potential. Furthermore, we study the Complex Morse and complex Coulomb potentials.

Khaled Saaidi

2003-09-15

423

Phase structure of the Higgs-Yukawa systems with chirally invariant lattice fermion actions

We develop analytical technique for examining phase structure of $Z_2$, $U(1)$, and $SU(2)$ lattice Higgs-Yukawa systems with radially frozen Higgs fields and chirally invariant lattice fermion actions. The method is based on variational mean field approximation. We analyse phase diagrams of such systems with different forms of lattice fermion actions and demonstrate that it crucially depends both on the symmetry group and on the form of the action. We discuss location in the diagrams of possible non-trivial fixed points relevant to continuum physics, and argue that the candidates can exist only in $Z_2$ system with SLAC action and $U(1)$ systems with naive and SLAC actions. [Note: By a product, missing term in Eq. (3.5) of hep-lat/9309010 is reconstructed, that, however, affects only the result of Sect. 4.3 (Fig. 3) of that reference (cf. Fig. 2(c) of this paper).

S. Tominaga; S. V. Zenkin

1994-03-04

424

Solitonic lattice and Yukawa forces in the rare-earth orthoferrite TbFeO3.

The random fluctuations of spins give rise to many interesting physical phenomena, such as the 'order-from-disorder' arising in frustrated magnets and unconventional Cooper pairing in magnetic superconductors. Here we show that the exchange of spin waves between extended topological defects, such as domain walls, can result in novel magnetic states. We report the discovery of an unusual incommensurate phase in the orthoferrite TbFeO(3) using neutron diffraction under an applied magnetic field. The magnetic modulation has a very long period of 340?Å at 3?K and exhibits an anomalously large number of higher-order harmonics. These domain walls are formed by Ising-like Tb spins. They interact by exchanging magnons propagating through the Fe magnetic sublattice. The resulting force between the domain walls has a rather long range that determines the period of the incommensurate state and is analogous to the pion-mediated Yukawa interaction between protons and neutrons in nuclei. PMID:22728320

Artyukhin, Sergey; Mostovoy, Maxim; Jensen, Niels Paduraru; Le, Duc; Prokes, Karel; de Paula, Vinícius G; Bordallo, Heloisa N; Maljuk, Andrey; Landsgesell, Sven; Ryll, Hanjo; Klemke, Bastian; Paeckel, Sebastian; Kiefer, Klaus; Lefmann, Kim; Kuhn, Luise Theil; Argyriou, Dimitri N

2012-08-01

425

Mixed Axion/Axino Dark Matter in mSUGRA and Yukawa-unified SUSY

Axion/axino dark matter (DM) is explored in the minimal supergravity (mSUGRA) and Yukawa-unified supersymmetric grand-unified theory (SUSY GUT) models with surprising results. For this type of scenario, relic DM abundance has three components: i.) cold axions, ii.) warm axinos from neutralino decay, and iii.) cold or warm thermally produced axinos. Reheat temperatures T{sub R} exceeding 10{sup 6} GeV are required in order to solve the gravitino/Big Bang Nucleosynthesis (BBN) problem while also allowing for baryogensis via non-thermal leptogenesis. In order to attain high enough reheat temperatures, we also need high values of the Peccei-Quinn (PQ) breaking scale f{sub a} on the order 10{sup 11}-10{sup 12} GeV.

Ann Summy, Heaya [Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

2010-02-10

426

Putting Yukawa-Like Modified Gravity (MOG) on the Test in the Solar System

NASA Astrophysics Data System (ADS)

We deal with a Yukawa-like long-range modified model of gravity (MOG) which recently allowed to successfully accommodate many astrophysical and cosmological features without resorting to dark matter. On Solar System scales, MOG predicts anomalous retrograde secular precessions of the planetary longitudes of the perihelia ?. Their existence has been put on the test here by taking the ratios of the observationally estimated Pitjeva's corrections to the standard Newtonian/ Einsteinian perihelion precessions for different pairs of planets. It turns out that MOG, in the present form which turned out to be phenomenologically successful on astrophysical scales, is ruled out at more than 3? level in the Solar System. If and when other teams of astronomers will independently estimate their own corrections to the usual precessions of the perihelia, it will be possible to repeat such a test.

Iorio, Lorenzo

2008-11-01

427

Higgs characterisation at NLO in QCD: CP properties of the top-quark Yukawa interaction

NASA Astrophysics Data System (ADS)

At the LHC the CP properties of the top-quark Yukawa interaction can be probed through Higgs production in gluon fusion or in association with top quarks. We consider the possibility for both CP-even and CP-odd couplings to the top quark to be present, and study CP-sensitive observables at next-to-leading order (NLO) in QCD, including parton-shower effects. We show that the inclusion of NLO corrections sizeably reduces the theoretical uncertainties, and confirm that di-jet correlations in $H+2$ jet production through gluon fusion and correlations of the top-quark decay products in $t\\bar tH$ production can provide sensitive probes of the CP nature of the Higgs interactions.

Demartin, Federico; Maltoni, Fabio; Mawatari, Kentarou; Page, Ben; Zaro, Marco

2014-09-01

428

Sparticle spectroscopy with neutralino dark matter from t-b-? quasi-Yukawa unification

NASA Astrophysics Data System (ADS)

We consider two classes of t-b-? quasi-Yukawa unification scenarios which can arise from realistic supersymmetric SO(10) and SU(4)C×SU(2)L×SU(2)R models. We show that these scenarios can be successfully implemented in the nonuniversal Higgs model with mHu=mHd?m0 and the constrained minimal sumersymmetric model frameworks, and they yield a variety of sparticle spectra with Wilkinson Microwave Anisotropy Probe compatible neutralino dark matter. In the nonuniversal Higgs model with mHu=mHd?m0, we find bino-Higgsino dark matter as well as the stau coannihilation and A-funnel solutions. The constrained minimal sumersymmetric model case yields the stau coannihilation and A-funnel solutions. The gluino and squark masses are found to lie in the TeV range.

Dar, Shahida; Gogoladze, Ilia; Shafi, Qaisar; Ün, Cem Salih

2011-10-01

429

Asymptotic behavior in a model with Yukawa interaction from Schwinger-Dyson equations

NASA Astrophysics Data System (ADS)

A system of Schwinger-Dyson equations for pseudoscalar four-dimensional Yukawa model in the two-particle approximation is investigated. The simplest iterative solution of the system corresponds to the mean-field approximation (or, equivalently, to the leading order of 1/N-expansion) and includes a non-physical Landau pole in deep-Euclidean region for the pseudoscalar propagator ?. It is argued, however, that a full solution may be free from non-physical singularities and has the self-consistent asymptotic behavior p^2_e\\Delta \\simeq C\\,log ^{-4/5}\\frac{p^2_e}{M^2}. An approximate solution confirms the positivity of C and the absence of Landau pole.

Rochev, V. E.

2012-05-01

430

Putting Yukawa-like Modified Gravity (MOG) on the test in the Solar System

We deal with a Yukawa-like long-range modified model of gravity (MOG) which recently allowed to successfully accommodate many astrophysical and cosmological features without resorting to dark matter. On Solar System scales MOG predicts retrograde secular precessions of the planetary longitudes of the perihelia \\varpi whose existence has been put on the test here by taking the ratios of the observationally estimated Pitjeva's corrections to the standard Newtonian/Einsteinian perihelion precessions for different pairs of planets. It turns out that MOG, in the present form which turned out to be phenomenologically successful on astrophysical scales, is ruled out at more than 3sigma level in the Solar System. If and when other teams of astronomers will independently estimate their own extra-precessions of the perihelia it will be possible to repeat such a test.

Lorenzo Iorio

2008-09-21

431

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

432

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

433

Structure Effects in Collisions Induced by Halo and Weakly Bound Nuclei around the Coulomb Barrier

NASA Astrophysics Data System (ADS)

In this contribution, results concerning different reaction channels for the collisions induced by the three Be isotopes, 9,10,11Be, on a 64Zn target at energies around the Coulomb barrier will be presented. The experiments with the radioactive 10,11Be beams were performed at REX-ISOLDE (CERN) whereas the experiment with the stable weakly bound 9Be beam was performed at LNS Catania. Elastic scattering angular distributions have been measured for the three systems 9,10,11Be + 64Zn at the same center of mass energy. The angular distributions were analyzed with optical potentials and reaction cross sections were obtained from optical model calculations, performed with the code PTOLEMY. For the 11Be + 64Zn reaction, the break-up angular distribution was also measured.

Scuderi, V.; di Pietro, A.; Acosta, L.; Amorini, F.; Borge, M. J. G.; Figuera, P.; Fisichella, M.; Fraile, L. M.; Gomez-Camacho, J.; Jeppesen, H.; Lattuada, M.; Martel, I.; Milin, M.; Musumarra, A.; Papa, M.; Pellegriti, M. G.; Raabe, R.; Randisi, G.; Rizzo, F.; Santonocito, D.; Sanchez, E. M. R.; Scalia, G.; Tengblad, O.; Torresi, D.; Vidal, A. M.; Zadro, M.

434

Electronically excited atom or molecule in an environment can relax via transferring its excess energy to the neighboring atoms or molecules. The process is called Interatomic or Intermolecular coulombic decay (ICD). The ICD is a fast decay process in environment. Generally, the ICD mechanism predominates in weakly bound clusters. In this paper, we have applied the complex absorbing potential approach/equation-of-motion coupled cluster (CAP/EOMCCSD) method which is a combination of CAP and EOMCC approach to study the lifetime of ICD at various geometries of the molecules. We have applied this method to calculate the lifetime of ICD in Ne-X; X = Ne, Mg, Ar, systems. We compare our results with other theoretical and experimental results available in literature. PMID:25527920

Ghosh, Aryya; Vaval, Nayana

2014-12-21

435

Electron dynamics of interatomic Coulombic decay in quantum dots induced by a laser field.

In this paper we investigated the dynamics of an electron in the presence of a time-dependent laser field in a model potential for a two-level single-electron semiconductor quantum dot (QD) that is capable of undergoing interatomic Coulombic decay (ICD) together with an electron bound to a neighboring QD. We demonstrate that ICD can be initiated by coupling the two-level QD to either a continuous or a pulsed moderate to strong laser and we obtain the total and partial decay widths of the resonance excited state in agreement with that from the solely decay of the resonance [A. Bande, K. Gokhberg, and L. S. Cederbaum, J. Chem. Phys. 135, 144112 (2011)]. A detailed discussion of the effects of direct ionization by the laser in single- or multi-photon process as well as Rabi oscillations is furthermore presented. PMID:23758355

Bande, Annika

2013-06-01

436

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

437

Topological defect formation and spontaneous symmetry breaking in ion Coulomb crystals.

Symmetry breaking phase transitions play an important role in nature. When a system traverses such a transition at a finite rate, its causally disconnected regions choose the new broken symmetry state independently. Where such local choices are incompatible, topological defects can form. The Kibble-Zurek mechanism predicts the defect densities to follow a power law that scales with the rate of the transition. Owing to its ubiquitous nature, this theory finds application in a wide field of systems ranging from cosmology to condensed matter. Here we present the successful creation of defects in ion Coulomb crystals by a controlled quench of the confining potential, and observe an enhanced power law scaling in accordance with numerical simulations and recent predictions. This simple system with well-defined critical exponents opens up ways to investigate the physics of non-equilibrium dynamics from the classical to the quantum regime. PMID:23921564

Pyka, K; Keller, J; Partner, H L; Nigmatullin, R; Burgermeister, T; Meier, D M; Kuhlmann, K; Retzker, A; Plenio, M B; Zurek, W H; del Campo, A; Mehlstäubler, T E

2013-01-01

438

NASA Astrophysics Data System (ADS)

We present a genetic algorithm based investigation of structural fragmentation in dicationic noble gas clusters, Arn+2, Krn+2, and Xen+2, where n denotes the size of the cluster. Dications are predicted to be stable above a threshold size of the cluster when positive charges are assumed to remain localized on two noble gas atoms and the Lennard-Jones potential along with bare Coulomb and ion-induced dipole interactions are taken into account for describing the potential energy surface. Our cutoff values are close to those obtained experimentally [P. Scheier and T. D. Mark, J. Chem. Phys. 11, 3056 (1987)] and theoretically [J. G. Gay and B. J. Berne, Phys. Rev. Lett. 49, 194 (1982)]. When the charges are allowed to be equally distributed over four noble gas atoms in the cluster and the nonpolarization interaction terms are allowed to remain unchanged, our method successfully identifies the size threshold for stability as well as the nature of the channels of dissociation as function of cluster size. In Arn2+, for example, fissionlike fragmentation is predicted for n =55 while for n =43, the predicted outcome is nonfission fragmentation in complete agreement with earlier work [Golberg et al., J. Chem. Phys. 100, 8277 (1994)].

Nandy, Subhajit; Chaudhury, Pinaki; Bhattacharyya, S. P.

2010-06-01

439

Band Structures of Narrow Gap Semiconductors in Terms of Coulombic Polaron Effect

We consider the formation of a polaron in an interacting Fermi gas due to Coulomb polarization of electron gas by a single\\u000a electron. We show that the polarization effect due to the Coulomb field in an interacting Fermi gas leads to the Coulomb polaron\\u000a caused by the exchange-correlation hole and the electron spectrum shows an insulating behavior with the dispersion

J. D. Fan; Y. M. Malozovsky; D. Bagayoko

2010-01-01

440

Improving Student Understanding of Coulomb's Law and Gauss's Law

NSDL National Science Digital Library

The paper discusses the development and evaluation of five research-based tutorials on Coulomb's law, superposition, symmetry and Gauss's Law to help students in the calculus-based introductory physics courses learn these concepts. They compare the performance of students on the pre-/post-tests given before and after the tutorials in three calculus-based introductory physics courses. They also compare the performance of students who used the tutorials and those who did not use it on a multiple-choice test which employs concepts covered in the tutorials.

Isvan, Zeynep; Singh, Chandralekha

2007-11-25

441

Coulombic Effects on the Traceless Staudinger Ligation in Water

The traceless Staudinger ligation can be mediated by phosphinothiols under physiological conditions. Proximal positive charges are necessary to achieve that transformation, presumably because those charges discourage protonation of the key iminophosphorane intermediate. Here, a series of cationic phosphinothiols is used to probe Coulombic effects on the traceless Staudinger ligations in aqueous buffers. The reagent bis(m-N,N-dimethylaminomethylphenyl)phosphinomethanethiol (3) is found to be superior to others, both in its ability to mediate traceless Staudinger ligations in water and in the efficiency of its synthesis. PMID:18314338

Tam, Annie; Raines, Ronald T.

2009-01-01

442

Conjugate Directions in Lattice Landau and Coulomb Gauge Fixing

We provide details expanding on our implementation of a non-linear conjugate gradient method with Fourier acceleration for lattice Landau and Coulomb gauge fixing. We find clear improvement over the Fourier accelerated steepest descent method, with the average time taken for the algorithm to converge to a fixed, high accuracy, being reduced by a factor of 2 to 4. We show such improvement for the logarithmic definition of the gauge fields here, having already shown this to be the case for a more common definition. We also discuss the implementation of an optimal Fourier accelerated steepest descent method.

R. J. Hudspith

2014-12-08

443

Imaging of Acoustic Waves in Piezoelectric Ceramics by Coulomb Coupling

NASA Astrophysics Data System (ADS)

The transport properties of bulk and guided acoustic waves travelling in a lead zirconate titanate (PZT) disc, originally manufactured to serve as ultrasonic transducer, have been monitored by scanned Coulomb coupling. The images are recorded by excitation and detection of ultrasound with local electric field probes via piezoelectric coupling. A narrow pulse has been used for excitation. Broadband coupling is achieved since neither mechanical nor electrical resonances are involved. The velocities of the traveling acoustic waves determined from the images are compared with characteristic velocities calculated from material properties listed by the manufacturer of the PZT plate.

Habib, Anowarul; Shelke, Amit; Pluta, Mieczyslaw; Kundu, Tribikram; Pietsch, Ullrich; Grill, Wolfgang

2012-07-01

444

The Coulomb excitations of Bernal bilayer graphene under external fields

We study the field effects on the Coulomb excitation spectrum of Bernal bilayer graphene by using the tight-binding model and the random-phase approximation. The electric field opens the band gap and creates the saddle points, the latter brings about a prominent interband plasmon. On the other hand, the magnetic field induces the dispersionless Landau levels (LLs) that causes the inter-LL plasmons. The two kinds of field-induced plasmon modes can be further tuned by the magnitude of momentum transfer and the field strength. The predicted results may be further validated by the inelastic light-scattering or high-resolution electron-energy-loss spectroscopy (HREELLS)

Wu, Jhao-Ying; Lin, Ming-Fa [Department of Physics, National Cheng-Kung University, Tainan 701, Taiwan (China)

2014-03-31

445

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

446

3He and 3H bound state for the Reid soft-core potential

NASA Astrophysics Data System (ADS)

The perturbational approach that has been used for the calculation of the triton bound state is applied to 3He. The Coulomb potential is fully taken into account within the limitation of the Reid soft-core-3 potential. We obtain 5.775 MeV as the binding energy of 3He. The Coulomb energy difference with 3H is 0.625 MeV. The Coulomb effects to the charge form factor and the two-body correlation function are calculated. Qualitative discussions are given for the complex behavior of the Faddeev components expressed in terms of the spectator momentum and the relative distance of the interacting pair. NUCLEAR STRUCTURE 3He and 3H bound state. Exact solution of the Faddeev equation by a perturbative approach. Binding energy of 3He: 5.775 MeV. Coulomb energy difference with triton: 0.625 MeV. Coulomb effects to charge form factor and correlation function.

Sasakawa, T.; Okuno, H.; Sawada, T.

1981-02-01

447

Modeling bound-to-continuum terahertz quantum cascade lasers: The role of Coulomb interactions

Based on an ensemble Monte Carlo analysis, we show that Coulomb interactions play a dominant role in bound-to-continuum terahertz quantum cascade lasers and thus require careful modeling. Coulomb interactions enter our simulation in the form of space charge effects as well as Coulomb scattering events. By comparison to a full many-subband Coulomb screening model, we show that simplified approaches produce considerable deviations for such structures. Also the spin dependence of electron-electron scattering has to be adequately considered. Moreover, we demonstrate that iterative Schr\\"{o}dinger-Poisson and carrier transport simulations are necessary to correctly account for space charge effects.

Jirauschek, Christian; Lugli, Paolo; 10.1063/1.3276160

2011-01-01

448

NUCLEAR PHYSICS: Coulomb effects on the formation of proton halo nuclei

NASA Astrophysics Data System (ADS)

This paper makes some qualitative and quantitative analyses about halo formation rules of some mirror nuclei with the relativistic mean-field (RMF) theory and the Woods-Saxon mean-field model. By analysing two opposite effects of Coulomb interaction on the proton halo formation, it finds that the energy level shift has a larger contribution than that of the Coulomb barrier when the mass number A is small, the hindrance of the Coulomb barrier becomes more obvious with the increase of the mass number A, and the overall effect of the Coulomb interaction almost disappears when A approx 39 as its two effects counteract with each other.

Liang, Yu-Jie; Li, Yan-Song; Zhu, Min; Liu, Zu-Hua; Zhou, Hong-Yu

2009-12-01

449

A Coulomb impurity placed in an undoped Weyl semimetal spontaneously surrounds itself with a cloud of condensed Weyl fermions. We study this system within the Thomas-Fermi approximation. We find that the ground-state of the system is electrically neutral and exhibits an experimentally accessible Landau zero-charge effect: the impurity charge is screened out at any finite distance in the limit of vanishing impurity size. Specifically, we show how in this limit the Thomas-Fermi equation for the electrostatic potential transforms into the Gell-Mann-Low equation for the charge.

Eugene B. Kolomeisky; Joseph P. Straley

2012-05-31

450

A Coulomb impurity placed in an undoped Weyl semimetal spontaneously surrounds itself with a cloud of condensed Weyl fermions. We study this system within the Thomas-Fermi approximation. We find that the ground-state of the system is electrically neutral and exhibits an experimentally accessible Landau zero-charge effect: the impurity charge is screened out at any finite distance in the limit of vanishing impurity size. Specifically, we show how in this limit the Thomas-Fermi equation for the electrostatic potential transforms into the Gell-Mann-Low equation for the charge.

Kolomeisky, Eugene B

2013-01-01

451

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

452

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

453

NASA Astrophysics Data System (ADS)

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 2.4×107 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 1.1×1012. 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.; Klimchitskaya, G. L.; Mostepanenko, V. M.; Romero, C.

2010-03-01

454

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{sub 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{sub min} is to be identified with the de Broglie wavelength; at superthermal drift the shielding cloud exhibits cylindrical (axial) symmetry and b{sub 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 interpretation that attributes b{sub 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.

Mulser, P., E-mail: peter.mulser@physik.tu-darmstadt.de; Alber, G. [Institut für Angewandte Physik, Technische Universität Darmstadt, D-64289 Darmstadt (Germany)] [Institut für Angewandte Physik, Technische Universität Darmstadt, D-64289 Darmstadt (Germany); Murakami, M. [ILE: Institute of Laser Engineering, Osaka University, Yamada Kami, Osaka (Japan)] [ILE: Institute of Laser Engineering, Osaka University, Yamada Kami, Osaka (Japan)

2014-04-15

455

Nontrival Coulomb staircase in single-electron turnstile devices

NASA Astrophysics Data System (ADS)

We extend the theory of single-electron turnstiles to incorporate the effects of the voltage-drop asymmetry and barrier suppression. We introduce two parameters of the theory-the barrier suppression energy ?T describing the barrier suppression and the voltage asymmetry factor c. In the limit Ec<Coulomb-blockade picture is recovered, while in the limit Ec>>?T a regime of nontrivial Coulomb blockade is established. The asymmetry factor c governs the structure of the staircase. For c=0,1 the steps have height 1e and width Ec, for c=1/2 they have height 2e and width 2Ec and for c=1/3, 2) / 3 the staircase is 1e-2e-1e-2e. . . . The last nontrivial staircase has been observed in a recent experiment by Kouwenhoven et al. Since this effect influences the length of the steps, it should be important in the design of current standards. Additional structures for such devices are discussed.

Groshev, Atanas

1992-10-01

456

Coulomb correlations in the honeycomb lattice: Role of translation symmetry

NASA Astrophysics Data System (ADS)

The effect of Coulomb correlations in the half-filled Hubbard model of the honeycomb lattice is studied within the dynamical cluster approximation (DCA) combined with exact diagonalization (ED) and continuous-time quantum Monte Carlo (QMC), for unit cells consisting of six-site rings. The important difference between this approach and the previously employed cluster dynamical mean-field theory (CDMFT) is that DCA preserves the translation symmetry of the system, while CDMFT violates this symmetry. As the Dirac cones of the honeycomb lattice are the consequence of perfect long-range order, DCA yields semimetallic behavior at small on-site Coulomb interactions U, whereas CDMFT gives rise to a spurious excitation gap even for very small U. This basic difference between the two cluster approaches is found regardless of whether ED or QMC is used as the impurity solver. At larger values of U, the lack of translation symmetry becomes less important, so that the CDMFT reveals a Mott gap, in qualitative agreement with large-scale QMC calculations. In contrast, the semimetallic phase obtained in DCA persists even at U values where CDMFT and large-scale QMC consistently show Mott-insulating behavior.

Liebsch, Ansgar; Wu, Wei

2013-05-01

457

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

458

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

459

Coulomb stress accumulation along the San Andreas Fault system

NASA Astrophysics Data System (ADS)

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.

Smith, Bridget; Sandwell, David

2003-06-01

460

Multi electron species and shielding potentials in plasmas

The phenomenon of Debye shielding is investigated in electron ion plasmas using the approach of two temperature electrons. We get different profiles of potential for different parameters and observe that the potentials fall very slowly than the standard Coulomb and Debye potentials. The importance of work is pointed out in the introduction.

Khan, Arroj A.; Murtaza, G. [Salam Chair in Physics, Government College University, Lahore 54000 (Pakistan); Rasheed, A.; Jamil, M. [Department of Physics, Government College University, Faisalabad 38000 (Pakistan)

2012-11-15

461

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

462

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

463

Density profiles and solvation forces for a Yukawa fluid in a slit pore.

The effect of varying wall-particle and particle-particle interactions on the density profiles near a single wall and the solvation forces between two walls immersed in a fluid of particles is investigated by grand canonical Monte Carlo simulations. Attractive and repulsive particle-particle and particle-wall interactions are modeled by a versatile hard-core Yukawa form. These simulation results are compared to theoretical calculations using the hypernetted chain integral equation technique, as well as with fundamental measure density functional theory (DFT), where particle-particle interactions are either treated as a first order perturbation using the radial distribution function or else with a DFT based on the direct-correlation function. All three theoretical approaches reproduce the main trends fairly well, but exhibit inconsistent accuracy, particularly for attractive particle-particle interactions. We show that the wall-particle and particle-particle attractions can couple together to induce a nonlinear enhancement of the adsorption and a related "repulsion through attraction" effect for the effective wall-wall forces. We also investigate the phenomenon of bridging, where an attractive wall-particle interaction induces strongly attractive solvation forces. PMID:18513039

Karanikas, S; Dzubiella, J; Moncho-Jordá, A; Louis, A A

2008-05-28

464

Freezing lines of colloidal Yukawa spheres. I. A Rogers-Young integral equation study

NASA Astrophysics Data System (ADS)

Using the Rogers-Young (RY) integral equation scheme for the static structure factor combined with the one-phase Hansen-Verlet (HV) freezing rule, we study the equilibrium structure and two-parameter freezing lines of colloidal particles with Yukawa-type pair interactions representing charge-stabilized silica spheres suspended in dimethylformamide (DMF). Results are presented for a vast range of concentrations, salinities and effective charges covering particles with masked excluded-volume interactions. The freezing lines were obtained for the low-charge and high-charge solutions of the static structure factor, for various two-parameter sets of experimentally accessible system parameters. All RY-HV based freezing lines can be mapped on a universal fluid-solid coexistence line in good agreement with computer simulation predictions. The RY-HV calculations extend the freezing lines obtained in earlier simulations to a broader parameter range. The experimentally observed fluid-bcc-fluid reentrant transition of charged silica spheres in DMF can be explained using the freezing lines obtained in this work.

Gapinski, Jacek; Nägele, Gerhard; Patkowski, Adam

2012-01-01

465

NASA Astrophysics Data System (ADS)

We describe a method for calculating the matrix elements of the Coulomb operator for Gaussian basis sets using an intermediate discrete Fourier transform of the density. Our goals are the same as those of the Gaussian and augmented-plane-wave method of Parrinello and co-workers [M. Krack and M. Parrinello, Phys. Chem. Chem. Phys. 2, 2105 (2000)], but our techniques are quite different. In particular, we aim at much higher numerical accuracy than typical programs using plane wave expansions. Our method is free of the effects of periodic images and yields full precision. Other low-scaling methods for the Coulomb operator are compared to the Fourier transform method with regard to numerical precision, asymptotic scaling with molecular size, asymptotic scaling with basis set size, onset point (the size of the calculation where the method outperforms traditional Gaussian integral techniques by a factor of 2), and the ability to calculate the Hartree-Fock exchange operator. The Fourier transform method is superior to alternatives by most criteria. In particular, for typical molecular applications it has an earlier onset point than fast multipole methods.

Fusti-Molnar, Laszlo; Pulay, Peter

2002-11-01

466

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

467

Evidence for 2kF electronelectron scattering processes in Coulomb drag

Evidence for 2kF electronÂelectron scattering processes in Coulomb drag M. Kellogga , J and calculations of Coulomb drag between two low density, closely spaced, two-dimensional electron systems are reported. The experimentally measured drag exceeds that calculated in the random phase approximation

Eisenstein, Jim

468

Coulomb Drag for Strongly Localized Electrons: A Pumping Mechanism M. E. Raikh1

Coulomb Drag for Strongly Localized Electrons: A Pumping Mechanism M. E. Raikh1 and Felix von Oppen through the active layer. We find that the microscopic origin of drag lies in the time correlations,2], Coulomb drag between two parallel elec- tronic layers has commanded a lot of attention. Stimu- lated

von Oppen, Felix

469

Coulomb Drag in Graphene Near the Dirac Point M. Schutt,1

Coulomb Drag in Graphene Near the Dirac Point M. SchuÂ¨tt,1 P. M. Ostrovsky,2,1,3 M. Titov,4 I. V 2012; published 7 January 2013) We study Coulomb drag in graphene near the Dirac point, focusing drag based on fast interlayer thermalization, inaccessible by standard perturbative approaches. Using

Fominov, Yakov

470

Coulomb drag in mesoscopic rings T. V. Shahbazyan and S. E. Ulloa

Coulomb drag in mesoscopic rings T. V. Shahbazyan and S. E. Ulloa Department of Physics 27 January 1997 We develop a Luttinger-liquid theory of the Coulomb drag of persistent currents nondissipative drag depends strongly on the relative parity of the electron numbers. We also show

Ulloa, Sergio E.

471

Coulomb Sum Rule Up to Three-Body Correlation Diagram in Linked Cluster Expansion

Coulomb sum rule is calculated up to three-body correlation diagrams in the linked cluster expansion, using the effective interaction. The relationship of these diagrams with the diagrammatic expansion of the response function is shown. The three-body correlation diagram contribution to the Coulomb sum rule is small for high momentum transfers.

M. Kohno

1981-01-01

472

Asymmetric Coulomb fluids at randomly charged dielectric interfaces: Anti-fragility, overcharging (2014) Asymmetric Coulomb fluids at randomly charged dielectric interfaces: Anti-fragility, overcharging of the contact- value theorem, reflecting the anti-fragility effects of the disorder that drive the system

Podgornik, Rudolf

473

Kinetic analysis of nuclear and Coulomb scattering in high-temperature tandem mirror plasmas

A two-dimensional kinetic theory analysis is used to determine distribution functions in high-temperature mirror plasmas in which both Coulomb and nuclear elastic scattering are important. The discrete nature of nuclear scattering and the continuous nature of Coulomb scattering are incorporated. The distribution functions are used to obtain the energy deposition and energy and particle loss rates for fusion reaction products

F. D. Kantrowitz; R. W. Conn

1984-01-01

474

Separable Optical Potentials for (d,p) Reactions

An important ingredient for applications of nuclear physics to e.g. astrophysics or nuclear energy are the cross sections for reactions of neutrons with rare isotopes. Since direct measurements are often not possible, indirect methods like (d,p) reactions must be used instead. Those (d,p) reactions may be viewed as effective three-body reactions and described with Faddeev techniques. An additional challenge posed by (d,p) reactions involving heavier nuclei is the treatment of the Coulomb force. To avoid numerical complications in dealing with the screening of the Coulomb force, recently a new approach using the Coulomb distorted basis in momentum space was suggested. In order to implement this suggestion, one needs not only to derive a separable representation of neutron- and proton-nucleus optical potentials, but also compute the Coulomb distorted form factors in this basis.

Ch. Elster; L. Hlophe; V. Eremenko; F. M. Nunes; G. Arbanas; J. E. Escher; I. J. Thompson

2014-10-05

475

Ultra-high-ohmic microstripline resistors for Coulomb blockade devices.

In this paper, we report on the fabrication and low-temperature characterization of ultra-high-ohmic microstripline resistors made of a thin film of weakly oxidized titanium. Nearly linear voltage-current characteristics were measured at temperatures down to T ~ 20 mK for films with sheet resistivities as high as ~7 k?, i.e. about an order of magnitude higher than our previous findings for weakly oxidized Cr. Our analysis indicates that such an improvement can help to create an advantageous high-impedance environment for different Coulomb blockade devices. Further properties of the Ti film addressed in this work show the promise of low-noise behavior of the resistors when applied in different realizations of the quantum standard of current. PMID:23670293

Lotkhov, Sergey V

2013-06-14

476

Ultra-high-ohmic microstripline resistors for Coulomb blockade devices

NASA Astrophysics Data System (ADS)

In this paper, we report on the fabrication and low-temperature characterization of ultra-high-ohmic microstripline resistors made of a thin film of weakly oxidized titanium. Nearly linear voltage-current characteristics were measured at temperatures down to T ˜ 20 mK for films with sheet resistivities as high as ˜7 k?, i.e. about an order of magnitude higher than our previous findings for weakly oxidized Cr. Our analysis indicates that such an improvement can help to create an advantageous high-impedance environment for different Coulomb blockade devices. Further properties of the Ti film addressed in this work show the promise of low-noise behavior of the resistors when applied in different realizations of the quantum standard of current.

Lotkhov, Sergey V.

2013-06-01

477