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In this study, we investigate the greybody factor of a (3+1)-dimensional black hole solution in the context of alternative f (Q) gravity with minimum scalar field coupling. We obtain the radial equation by applying the Klein–Gordon equation and transforming it into a Schrodinger wave equation using the tortoise coordinate. This transformation enables us to determine the effective potential and its graphical behavior for different values of the coupling constant and relevant physical parameters. We obtain two solutions for the radial equation corresponding to the event and cosmological horizons. To determine the greybody factor and its behavior, we combine these two solutions in the intermediate regime. The greybody factor increases with an increase in radius and coupling constant. This indicates that in alternative gravity, the larger black hole will die sooner as compared to cosmic gravity. [ABSTRACT FROM AUTHOR]

The asteroid 101955 Bennu is the target asteroid of the ongoing asteroid sample return mission OSIRIS-REx from NASA. In the mission, the spacecraft is scheduled to rendezvous with Bennu in August 2018. Investigating the dynamics of surface motion can offer guidance for further hopping landers or even sample return missions regarding Bennu or similarly irregular-shaped asteroids. This paper presents the free motion of sample particles on and above the surface of Bennu. The concepts and equations that govern the motion of a particle on and above the surface of an asteroid are briefly introduced. Trajectories of a number of particles' free motion are numerically calculated by considering four scenarios with different restitution coefficients. Initial positions of those particles are all randomly given on the surface of Bennu and their initial velocities are set as zero. The distribution of final locations of those sample particles is summarized and analyzed. Both the gravitational potential and its effective potential on the surface of Bennu are calculated to give a possible reason for the distributing characteristics. • The free motion tendency of surface particles of Bennu are revealed. • The effective potential on the surface of Bennu as a polyhedron is calculated. • The reason for the free motion tendency of particles is given. [ABSTRACT FROM AUTHOR]

We present an experimental study of effective potential for several particle concentration cases in a bi-dimensional granular model of a glass-forming liquid during cooling. From particle positions, we obtained the radial distribution function and then based on it, the effective potential for the interparticle interaction is extracted via the Ornstein–Zernike equation using Percus–Yevick, hypernetted chain, and Rogers–Young closure relations. We note that the effective potential obtained via the Percus–Yevick approach is the one that best describes our system. The resulting effective potential shows how the spatial correlation increases, as observed through the formation of attractive wells while, the temperature decreases. In cases of high particle concentration close to the glass transition, we observed that several attractive wells appear in the effective potential curve. Under these conditions, particles are arrested by neighboring particles but retain enough kinetic energy to interact at long distances and produce structural changes in the system. For cases of low particle concentration, the changes in the effective potential as the system cools are very small. • Effective potential evolves from repulsive to attractive as temperature decreases. • Structures present higher local order as particle concentration increases. • The Perkus–Yevick approach describes better the physical behavior of the system. • Near glass transition temperature effective potential attractive wells are deeper. • As the temperature diminishes a well first appears and then goes deeper. [ABSTRACT FROM AUTHOR]

Ten years ago the 125 GeV Higgs resonance was discovered at the LHC [1,2] , if this boson is a fundamental particle or a particle composed of new strongly interacting particles is still an open question. If this is a composite boson there are still no signals of other possible composite states of this scheme, a possible solution to this problem was recently discussed in Refs. [30,31] , where it is argued that the Higgs boson can be a composite dilaton [30]. In this work, considering an effective potential for composite operators we verify that the potential responsible for a light composite scalar boson of O (120) GeV, behaves like ∝ Φ 4 suggesting that if the Higgs boson is a composite scalar it may be a composite dilaton. [ABSTRACT FROM AUTHOR]

This paper develops the method of envelope equations to describe the oscillatory motion of ions in quadrupole mass analysers with round rods. Nonlinear equations for the description of the envelope dynamics are obtained taking into account the dodecapole (twelve-pole), the icosapole (twenty-pole) and octopole field distortions. It is shown that the effective potential which determines the ion vibration envelope has a quadratic part, with a magnitude and sign that depend on the location of the ion working point. It also contains a nonlinear part, which does not depend on the ion working point location near the tip of the first stability zone. The motion of ions in quadrupole mass filters with cylindrical rods has a nonlinear character at a theoretical mass resolving power over 1000. In the linear approach, nonlinear effects of the ion motion occur in a narrow zone near the boundaries of the first stability region. This explains low sensitivity of mass analysis within stability islands, which is a direct result of the quadrupole excitations at a frequency different from the main excitation frequency. Thus, the boundaries do not depend on nonlinear field distortions. The results of this theoretical approach are illustrated using the transmission peak shape modelling for mass analysers with different values of the rod radius r relative to the inscribed radius r 0 . It is shown, that the 6th and 10th order field distortions never compensate each other. However, the octopole field suppresses them completely in the range 1.115 < r / r 0 < 1.135, which is considered as an optimum. It is also shown that very substantial improvements in a peak shape can be achieved by adding minor (less than 1%) octopole distortions. [ABSTRACT FROM AUTHOR]

Pseudopotential models for radio frequency (rf) electric fields are widely used. However, these approximate and sometimes intuitively introduced methods, can sometimes lead to ambiguities and false conclusions. While a classical model works well for quadrupole fields with small q where the Mathieu parameter β ≤ 0.4 there has been some discussion in the literature of the behavior of a pseudopotential, and, in particular, the secular frequency of ions for larger q near the far end of the stability zone (for example, near q max ≈ 0.908045 for a = 0). This paper analyzes carefully the behavior of secular frequencies calculated both numerically and analytically and demonstrates that the classical formula for the secular frequency in the pseudopotential, ω = β Ω / 2 remains valid up to β = 1. This means that both the secular frequency and the pseudopotential function well depth increase monotonically with q inside the stability zone. However, some models state that the well depth, identified as the pseudopotential function calculated at the edge of a quadrupole aperture, should be zero at both the low q and high q boundaries of the stability zone, with a maximum somewhere between. It is shown that the paradox that the acceptance is zero at both ends of the stability zone and hence the pseudopotential well depth and the pseudopotential quadratic coefficient should be zero at both boundaries of the stability zone is resolved by introducing for large q a pseudopotential well depth and a pseudopotential well width as separate pseudopotential objects to characterize the acceptance, while a quadratic pseudopotential function is used to describe the secular motion of ions but not the acceptance for large q . [ABSTRACT FROM AUTHOR]

High-order expanded interatomic effective potential and Debye-Waller factors (DWFs) for local vibrational amplitudes in X-ray absorption fine structure (XAFS) of bcc crystals have been studied based on the anharmonic correlated Debye model. DWFs are presented in terms of cumulant expansion up to the fourth order and the many-body effects are taken into account in the present one-dimensional model based on the first shell near neighbor contribution approach used in the derivations of the anharmonic effective potential and XAFS cumulants where Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions for the dispersion relation, correlated Debye frequency and temperature and four first temperature-dependent XAFS cumulants have been derived based on the many-body perturbation approach. Thermodynamic properties and anharmonic effects in XAFS of bcc crystals described by the obtained cumulants have been in detail discussed. The advantage and efficiency of the present theory are illustrated by good agreement of the numerical results for Mo, Fe and W with experiment. [ABSTRACT FROM AUTHOR]

A new model for a colloidal size-asymmetric binary mixture is proposed: The Square-Shoulder-Asakura–Oosawa. This belongs to the larger class of non-additive hard-spheres models and has the property that its effective pair formulation is exact whenever the solvent particle fits inside the interstitial region of three touching solute particles. Therefore one can study its properties from the equivalent one-component effective problem. Some remarks on the phase diagram of this new model are also addressed. [ABSTRACT FROM AUTHOR]

Motivated by experiments in bosonic mixtures composed of a single element in two different hyperfine states, we study bosonic binary mixtures in the presence of Josephson interactions between species. We focus on a particular model with O ( 2 ) isospin symmetry, lifted by an imbalanced population parametrized by a Rabi frequency, Ω R , and a detuning, ν , which couples the phases of both species. We have studied the model at mean-field approximation plus Gaussian fluctuations. We have found that both species simultaneously condensate below a critical temperature T c and the relative phases are locked by the applied laser phase, α . Moreover, the condensate fractions are strongly dependent on the ratio Ω R / ∣ ν ∣ that is not affected by thermal fluctuations. [ABSTRACT FROM AUTHOR]

An effective potential to describe ion motion in radio frequency (rf) quadrupole fields is developed. It is based on the Mathieu equation instead of the standard averaging technique. An effective Hamiltonian series equation which is the extension of the classical effective potential approach allows determining the frequencies more accurately than in the case of the classical approach to the derivation of the effective potential; the latter uses only the first member of a Taylor series. Because the quadrupole potential is quadratic, time averaging of all the harmonics of the oscillation frequencies is possible and in this work all harmonics are considered using a strict mathematical background. The method can be applied to quadrupole operation at any value of the Mathieu parameters ( a , q ). With this method the ion motion in a quadrupole field is described by an effective quadratic potential and inside the stability zones this is a simple harmonic oscillator. It is shown that for a linear radio frequency (rf) quadrupole, with rf-only operation in the first stability region, the effective potential well depth, D , increases continuously with q and is given by the well-known relation D = q V 0 / 4 where V 0 is the amplitude of the rf voltage, pole to ground; however, here its validity is proved for q values up to the stability boundary at q = 0.9080. The potential well size (i.e., the acceptable range of initial coordinates) is separated from the potential well depth (i.e., the acceptable range of initial kinetic energies). The theory also allows calculating the acceptable range of initial coordinates, and it is shown that these decrease with increasing q as ≈ r 0 1 − q / q * (where q * = 0.9080 is the high q boundary of the first stability zone, and r 0 is the radius of the gap between electrodes) while the acceptable range of initial kinetic energies is still controlled by the potential well depth calculated as D = q V 0 / 4 . Preliminary numerical experiments and an alternate approach show the validity of the results. [ABSTRACT FROM AUTHOR]

We consider the classically scale invariant Higgs-dilaton model of dynamical symmetry breaking extended with an extra scalar field that plays the role of dark matter. The Higgs boson is light near a critical boundary between different symmetry breaking phases, where quantum corrections beyond the usual Gildener-Weinberg approximation become relevant. This implies a tighter connection between dark matter and Higgs phenomenology. The model has only three free parameters, yet it allows for the observed relic abundance of dark matter while respecting all constraints. The direct detection cross section mediated by the Higgs boson is determined by the dark matter mass alone and is testable at future experiments. [ABSTRACT FROM AUTHOR]

The stability conditions of a renormalization group improved effective potential have been discussed in the case of scalar QED and QCD with a colorless scalar. We calculate the same potential in these models assuming the existence of non-perturbative fixed points associated with a conformal phase. In the case of scalar QED the barrier of instability found previously is barely displaced as we approach the fixed point, and in the case of QCD with a colorless scalar not only the barrier is changed but the local minimum of the potential is also changed. [ABSTRACT FROM AUTHOR]

The results of an experiment on transmitting UCN through a rotating disc made of silicon single crystal are reported. They demonstrate that the transmission of the sample remains constant if it moves parallel to its surface. The range of neutron velocities in the system of reference associated with the sample is 6-38 m/s. It is found that the real and imaginary parts of the effective potential are constant to within 3x10-3. [ABSTRACT FROM AUTHOR]

Abstract: We study the model of a biaxial single ferromagnetic spin Hamiltonian with an external magnetic field applied along the medium axis. The phase transition of the escape rate is investigated. Two different but equivalent methods are implemented. Firstly, we derive the semi-classical description of the model which yields a potential and a coordinate dependent mass. Secondly, we employ the method of spin-particle mapping which yields a similar potential to that of semi-classical description but with a constant mass. The exact instanton trajectory and its corresponding action, which have not been reported in any literature is being derived. Also, the analytical expressions for the first- and second-order crossover temperatures at the phase boundary are derived. We show that the boundary between the first-and the second-order phase transitions is greatly influenced by the magnetic field. [Copyright &y& Elsevier]

Abstract: We applied a molecular dynamics simulation technique to charged colloidal systems in order to investigate small ion distribution in thermal equilibrium and to evaluate the effective interaction among macroions. For a system containing a single macroion, screening by counterions was evaluated. The screening becomes more complete for larger macroion charge. In spite of the large inhomogeneity, the chemical potential of small ions is constant for the entire system. Using a thermodynamic integral method, the effective potential (Helmholtz free energy) for two-macroion systems was evaluated as a function of macroion separation distance, and found to be repulsive under normal conditions. Many-body effect is also discussed by comparing the effective potentials for two- and three-macroion systems. [Copyright &y& Elsevier]

The study of greybody factor helps us to understand the quantum nature of the black hole. Gravitational potentials and bounds on the greybody factors for some well known black holes are developed and we investigate the influence of Born–Infeld and massive gravity parameters on them. It is observed that greybody factor bounds depend on the shape of effective potential. For higher values of effective potential, it becomes difficult for the waves to transmit and hence reduces the greybody factor bounds. It is also worthwhile to mention here that charge works as barrier and cosmological constant increases the emission rate of Hawking radiation. It is also observed that the energy of emitted particles increases which results in the enhancement of the greybody factor bound. We also discuss the relationship of transmission probability and reflection probability. • Gravitational potentials and bounds on the greybody factors for some well-known black holes are being developed. • It is observed that greybody factor bounds depend on the shape of effective potential. • It is also observed that the energy of emitted particles increases which results the enhancement of the greybody factor bound. • We also discuss the relationship of transmission probability and reflection probability. [ABSTRACT FROM AUTHOR]

Abstract: The formalism introduced by Cornwall, Jackiw and Tomboulis (CJT) provides a systematic approach to consistently resumming non-perturbative effects in Quantum Thermal Field Theory. One major limitation of the CJT effective action is that its loopwise expansion introduces residual violations of possible global symmetries, thus giving rise to massive Goldstone bosons in the spontaneously broken phase of the theory. In this paper we develop a novel symmetry-improved CJT formalism for consistently encoding global symmetries in a loopwise expansion. In our formalism, the extremal solutions of the fields and propagators to a loopwise truncated CJT effective action are subject to additional constraints given by the Ward Identities due to global symmetries. By considering a simple scalar model, we show that, unlike other methods, our approach satisfies a number of important field-theoretic properties. In particular, we find that the Goldstone boson resulting from spontaneous symmetry breaking of is massless and the phase transition is a second-order one, already in the Hartree–Fock approximation. After taking the sunset diagrams into account, we show how our approach properly describes the threshold properties of the massless Goldstone boson and the Higgs particle in the loops. Finally, assuming minimal modifications to the Hartree–Fock approximated CJT effective action, we calculate the corresponding symmetry-improved CJT effective potential and discuss the conditions for its uniqueness for scalar-field values away from its minimum. [Copyright &y& Elsevier]

Abstract: We consider derivation of the effective potential for a scalar field in curved space–time within the physical regularization scheme, using two sorts of covariant cut-off regularizations. The first one is based on the local momentum representation and Riemann normal coordinates and the second is operatorial regularization, based on the Fock–Schwinger–DeWitt proper-time representation. We show, on the example of a self-interacting scalar field, that these two methods produce equal results for divergences, but the first one gives more detailed information about the finite part. Furthermore, we calculate the contribution from a massive fermion loop and discuss renormalization group equations and their interpretation for the multi-mass theories. [Copyright &y& Elsevier]

Abstract: A construction of the Coulomb–Breit Hamiltonian for a pair of fermions, considered as a quantum two-body system, immersed in an arbitrary background gravitational field described by Einsteinʼs General Relativity is presented. Working with Fermi normal coordinates for a freely falling observer in a spacetime region where there are no background sources and ignoring the gravitational back-reaction of the system, the effective Coulomb–Breit Hamiltonian is obtained starting from the S-matrix element corresponding to the one-photon exchange between the charged fermionic currents. The contributions due to retardation are considered up to order and they are subsequently written as effective operators in the relativistic quantum mechanical Hilbert space of the system. The final Hamiltonian includes effects linear in the curvature and up to order . [Copyright &y& Elsevier]

Abstract: We investigate lattice Weinberg–Salam model without fermions for the value of the Weinberg angle , and bare fine structure constant around . We consider the value of the scalar self coupling corresponding to bare Higgs mass around 150 GeV. The effective constraint potential for the zero momentum scalar field is used in order to investigate phenomena existing in the vicinity of the phase transition between the physical Higgs phase and the unphysical symmetric phase of the lattice model. This is the region of the phase diagram, where the continuum physics is to be approached. We compare the above mentioned effective potential (calculated in selected gauges) with the effective potential for the value of the scalar field at a fixed space–time point. We also calculate the renormalized fine structure constant using the correlator of Polyakov lines and compare it with the one-loop perturbative estimate. [Copyright &y& Elsevier]

Abstract: The purpose of this work is to expand on the theory presented by Silveira et al. [Silveira et al., International Journal of Mass Spectrometry 296 (2010) 36–42], to include a detailed discussion of discrete ion transport properties in the periodic-focusing DC ion guide (PDC IG) that result in radial ion focusing and ion mobility. We previously noted that although the PDC IG utilizes only electrostatic fields, ions are subjected to an effective RF as they traverse the device in the axial (z) direction. Here, the radial electric field (E r ) oscillations generating the effective RF are investigated in detail. Equations of motion are derived to explain ion movement in the radial (r) direction. The results suggest that a collisionally dampened effective potential (V*) model can explain the observed radial ion confinement. Furthermore, a mathematical explanation regarding the effects of the non-uniform axial electric field and periodic collisional cooling phenomena generated in the PDC IG is presented in the context of ion mobility spectrometry (IMS). Included is a detailed discussion of the ion mobility coefficient (K), ion mobility resolution (R), and subsequent determination of the ion-neutral collision cross section (Ω) using the PDC IG. The results indicate that the PDC IG affords straightforward and accurate determination of K and Ω via incorporation of a mobility damping coefficient (α) which is easily derived based upon the operating conditions and the electrode geometry. [Copyright &y& Elsevier]

Abstract: Temperature dependence of the properties of strong-coupling bipolaron in a quantum dot (QD) is studied based on the Lee–Low–Pines–Huybrechts variational method and quantum statistical theory. Results of the numerical calculation show that the vibration frequency as well as the absolute value of the induced potential and the effective potential all increase with increasing coupling strength and temperature, respectively, and they also increase with decreasing relative distance of electrons. The bipolarons are closer and more stable when the temperature is higher and coupling strength is larger. The influence of radius of QD and dielectric constant ratio on the effective potential is little. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we provide a comprehensive understanding of the radial ion focusing mechanism in the periodic-focusing DC ion guide (PDC IG). The PDC IG was developed in our laboratory to improve the sensitivity and throughput of ion mobility spectrometry (IMS) with respect to conventional uniform field IMS. Radial ion focusing, which is responsible for the sensitivity improvement, is attributed to the presence of effective potentials created by the fringing electric fields of thick ring electrodes and collisional cooling of the ions with the neutral buffer gas. The ion focusing mechanism is affirmed by investigating the variations in the effective ion temperature (T eff ) which are dependent upon axial position in the device. The concepts derived herein outline guidelines for the design of high performance PDC IG ion mobility instruments and other ion optical devices such as periodic-focusing DC ion funnels. [ABSTRACT FROM AUTHOR]

Abstract: Outer resonances are studied as one type of quasinormal modes in two-dimensional dielectric cavities with refractive index . The outer resonances can be verified as the resonances which survive only outside the cavity in the small opening limit of the dielectric disk. We have confirmed that the outer resonances universally exist in deformed cavities irrespective of the geometry of cavity and they split into nearly degenerate states in slightly deformed cavity. Also we have introduced an extended interpretation of the effective potential analogy for the outer resonances. Since most outer resonances in the dielectric cavities have quite high leakages, they would affect to the broad background in the density of states. But, for TE polarization case, relatively low-leaky outer resonances exist and it presents the possibility that they can interact with the inner resonances. [Copyright &y& Elsevier]

Abstract: It is shown that the effective carrier interaction in semiconductor thin films, which is essentially of a non-Coulomb type, depends on the layer thickness but it is not sensitive to the form of quantum well. As a consequence the analytical expression for the effective 2D interaction potential, obtained using the parabolic quantum well model, can be used as a general (model-independent) formula. As an example, we have considered the electrons localized in a quantum dot. It is demonstrated that, when the quantum well confinement is much stronger than the lateral one, the results obtained using the 2D approach with the effective potential are in a good agreement with the full 3D calculations. [Copyright &y& Elsevier]

Abstract: The well-established effective action and effective potential framework from the quantum field theory domain is adapted and successfully applied to classical field theories of the Doi and Peliti type for diffusion controlled reactions. Through a number of benchmark examples, we show that the direct path integral calculation of the effective potential in fixed space dimension to one-loop order reduces to a small set of simple elementary functions, irrespective of the microscopic details of the specific model. Thus the technique, which allows one to obtain with little additional effort, the potentials for a wide variety of different models, represents an alternative to the standard model-dependent diagram-based calculations. The renormalized effective potential, effective equations of motion and the associated renormalization group equations are computed in spatial dimensions for a number of single species field theories of increasing complexity. [Copyright &y& Elsevier]

Abstract: The possibility that price dynamics is affected by its distance from a moving average has been recently introduced as new statistical tool. The purpose is to identify the tendency of the price dynamics to be attractive or repulsive with respect to its own moving average. We consider a number of tests for various models which clarify the advantages and limitations of this new approach. The analysis leads to the identification of an effective potential with respect to the moving average. Its specific implementation requires a detailed consideration of various effects which can alter the statistical methods used. However, the study of various model systems shows that this approach is indeed suitable to detect hidden forces in the market which go beyond usual correlations and volatility clustering. [Copyright &y& Elsevier]

Abstract: The concept of the effective potential provides inadequate estimation of the ion energy in RF-driven quadrupole fields. It is especially limited for the quantitation of additional enthalpy introduced by the RF-driven field for an ion molecule reaction. On the contrary, the effective potential is clearly successful in describing of the ion oscillation frequency, and has been surprisingly powerful considering the strict limitations of the adiabatic approximation. This work is an attempt to understand this contradiction and to consider a novel concept of the estimation of the ion energy in an RF field. This theoretical model for the averaged ion energy is useful in describing specific features of the RF field contribution to the enthalpy of ion molecule reactions. To demonstrate this effect, several ion molecule reactions are investigated experimentally including cluster formation, endothermic and exothermic oxidation reactions. [Copyright &y& Elsevier]

Abstract: The transport properties of coupled Brownian motors in rocking ratchet are investigated via solving Langevin equation analytically and numerically. In comparison with the result of single particle, our results show that the center-of-mass of elastically coupled Brownian motors moves faster than the corresponding single particle, and the efficiency and the Pe number of coupled Brownian motors are larger than those of the single Brownian motor. The reason is that in rocking ratchet the co-operative interplay between the interaction between coupled particles and external nonequilibrium fluctuations facilitates the directed motion and energy conversion. [Copyright &y& Elsevier]

Abstract: We show that in (3–3–1) models embedded with a singlet scalar playing the role of the axion, after imposing scale invariance, the breaking of Peccei–Quinn symmetry occurs through the one-loop effective potential for the singlet field. We, then, analyze the structure of spontaneous symmetry breaking by studying the new scalar potential for the model, and verify that electroweak symmetry breaking is tightly connected to the 3–3–1 breaking by the strong constraints among their vacuum expectation values. This offers a valuable guide to write down the correct pattern of symmetry breaking for multi-scalar theories. We also obtained that the accompanying massive pseudo-scalar, instead of acquiring mass of order of Peccei–Quinn scale as we would expect, develops a mass at a much lower scale, a consequence solely of the breaking via Coleman–Weinberg mechanism. [Copyright &y& Elsevier]

Abstract: We discuss the discrete light-cone quantization (DLCQ) of a scalar field theory on the maximally supersymmetric pp-wave background in ten dimensions. It has been shown that the DLCQ can be carried out in the same way as in the two-dimensional Minkowski spacetime. Then, the vacuum energy is computed by evaluating the vacuum expectation value of the light-cone Hamiltonian. The results are consistent with the effective potential obtained in our previous work [hep-th/0402028]. [Copyright &y& Elsevier]

Abstract: The quantum dynamics of a bulk-boundary theory is closely examined by the use of the background field method. As an example we take the Mirabelli–Peskin model, which is composed of 5D super-Yang–Mills (bulk) and 4D Wess–Zumino (boundary). Singular interaction terms play an important role of canceling the divergences coming from the KK-mode sum. Some new regularization of the momentum integral is proposed. An interesting background configuration of scalar fields is found. It is a localized solution of the field equation. In this process of the vacuum search, we present a new treatment of the vacuum with respect to the extra coordinate. The “supersymmetric” effective potential is obtained at the 1-loop full (w.r.t. the coupling) level. This is the bulk-boundary generalization of the Coleman–Weinberg''s case. Renormalization group analysis is done and the correct 4D result is reproduced. The Casimir energy is calculated and is compared with the case of the Kaluza–Klein model. [Copyright &y& Elsevier]

The properties of a ratchet system rectifying the random motion of two harmonically coupled particles with arbitrary coupling strengths are studied via Langevin simulations. In comparison with the result of single particle, our results show that the average center-of-mass velocity vc of two particles is larger than the average velocity v1 of single particle in the rocking ratchet for low-to-moderate noise intensities, however, vc in the flashing ratchet. The former is due to the decrease of effective barrier that the center-of-mass of two particles feels, and the latter is because of the distance of two diffusing particles across the nearest barrier increasing effectively. Numerical results are performed for a larger parameter regime and the validation of the proposed effective potential is illustrated. [Copyright &y& Elsevier]

We calculate effective potentials in scalar field theories on the maximally supersymmetric pp-wave background in ten dimensions. For this purpose we have to work in the light-cone formulation, and hence we introduce two methods to compute them in the light-cone frame. One is to use the Yan''s formula for evaluating one-loop correction terms. The other is to introduce a cut-off for the light-cone momentum. These methods are also confirmed in the case of Minkowski spacetime. [Copyright &y& Elsevier]

In a field theoretical context, we consider the effective potential associated to the Ginzburg–Landau model compactified in one of the spatial dimensions. We are able to determine the dependence of the transition temperature (Tc) for a system confined between two parallel planes as a function of distance (L) separating them. We show that Tc is a decreasing linear function of L−1 and obtain the critical separation for the suppression of the transition. [Copyright &y& Elsevier]

Analytical transfer matrix method (ATMM) for arbitrary spherically symmetrical potentials is extended from one dimension to three dimensions. Comparison with the numerical method and the shifted 1/N expansion method shows that proposed analysis is as exact as the numerical method. [Copyright &y& Elsevier]

We have investigated the impact of quantum mechanical space-quantization effects on the operation of a narrow-width SOI device structure. The presence of a two-dimensional carrier confinement gives rise to larger average displacement of the carriers from the interface proper and lower sheet electron density in the channel region. This, in turn, results not only in a significant increase in the threshold voltage but also in its pronounced channel width dependency. In this work, we have used classical 3D Monte Carlo particle-based simulations. Quantum mechanical space-quantization effects have been accounted for via an effective potential scheme that has been quite successful in describing bandgap widening effect and charge set back from the interface. [Copyright &y& Elsevier]

We prepared the indium doped MgB2 bulk sample by conventional solid state reaction. Systematic measurements of resistance versus temperature were performed on the sample with different transport current and different applied magnetic field. The curves of resistance in opposition to temperature are broadened with different transport current in transmitting temperature range. We present a method for the first time to analyze the experimental data and explore the pinning mechanisms of MgB2 for such kind of experiments. By analyzing on the experimental data, we found that the effective potential Ueff(T,H,J) is of logarithmic form in our experimental temperature and applied magnetic field regime. The curve U0(T,J) is linear dependent on temperature but the slope coefficient is changing lower near onset critical temperature. [Copyright &y& Elsevier]

We propose a method to find the effective pinning potential from magnetization hysteresis loops at different temperature directly. As an example, the pinning characteristics of MgB2 are studied. The form of the effective pinning potential Ueff dependence on temperature, applied magnetic field and current density is also obtained. [Copyright &y& Elsevier]

As a new superconductor, MgB2 has many different characteristic features in contrast to the traditional HTSC. The investigation of these features is important both for theoretical study and application of this material. Several groups reported that from the vortex phase diagram of MgB2, 3D vortex glass phase and vortex liquid phase are found. But the flux dynamic mechanism held by this new superconductor could not be considered as a merely a copy of those of the HTSC. While the former is a s-wave superconductor, the latter is d-wave superconductor. In the present article, we present an extensive investigation on the flux mechanism in MgB2 by transport measurement from 5 K to Tc of the sample at magnetic fields up to 7 T, and deal with the experimental data with the linear simulation method within framework of the thermally assisted flux flow theory, which was first proposed by Kes et al. Finally, we obtained an exact expression of the pinning barrier U0 in the liquid phase of vortex matter of MgB2. [Copyright &y& Elsevier]

A new mechanism of the phase transition (PT) in crystals such as KH2PO4 is proposed and theoretically studied. According to the model the proton subsystem plays a role of starting mechanism of the PT in the heavy ion system. It is shown for observing the isotopic replacement of the critical temperature it is enough to take into account the geometrical isotopic effect without special reference to the process of tunneling. [Copyright &y& Elsevier]

Vacuum structure and global cosmic strings are analyzed in the effective theory of self-interacting O(2) scalar fields on (3+1)-manifolds with conical singularities. In the context of one-loop effective action computed by heat-kernel methods with ζ-function regularization, we find an inhomogeneous vacuum of minimum energy and suggest some reason why low-energy global strings are likely to be generated at the conical singularities. [Copyright &y& Elsevier]

An optimized Rayleigh–Schro¨dinger expansion scheme of solving the functional Schro¨dinger equation with an external source is proposed to calculate the effective potential beyond the Gaussian approximation. For a scalar field theory whose potential function has a Fourier representation in a sense of tempered distributions, we obtain the effective potential up to the second order, and show that the first-order result is just the Gaussian effective potential. Its application to the λφ4 field theory yields the same post-Gaussian effective potential as obtained in the functional integral formalism. [Copyright &y& Elsevier]

In this review article we give an overview of the basic techniques used in the field of computational electronics related to the simulation of state-of-the art devices fabricated in a variety of device technologies. We begin with a review of the electronic band structure and the associated dynamics of the carriers under external fields, followed by a discussion of the basic equations governing transport in semiconductors, and leading to the description of the Monte Carlo method for the solution of the Boltzmann transport equation and the simplified hydrodynamic and drift-diffusion models. We also give an overview of field solvers for both high-frequency and low-frequency application, followed by a description of particle-based simulation tools for both low and high-frequency applications. The need of more sophisticated simulation tools that go beyond the Boltzmann transport picture is also addressed, and is followed with the description of the two approaches that allow successful and rather inexpensive (in terms of needed CPU time) incorporation of quantum-mechanical space-quantization effects into existing semi-classical device simulators: the effective-potential approach and the quantum hydrodynamic model. Examples derived from our own research are given throughout the text to illustrate the usefulness and the limitations of the computational techniques discussed in this review. [Copyright &y& Elsevier]

The Coleman-Weinberg mechanism can realise different phases of dynamical symmetry breaking. In each phase a combination of scalars, corresponding to the pseudo-Goldstone boson of scale invariance, has a loop-suppressed mass. We show that additional scalars, beyond the pseudo-Goldstone bosons, can become light at critical points in the parameter space where two different phases co-exist. We present a minimal implementation of the mechanism in multi-scalar models, detailing how loop-suppressed masses and mixings can be computed. We discuss realisations of the resulting multi-phase criticality principle and its relevance to the case of the Higgs boson. [ABSTRACT FROM AUTHOR]

Regular and chaotic Behavior of dihedral angle with increasing amount of quantum effects. • Torsional motion in molecular dynamics is studied through a semiquantal approach. • An equivalent potential is proposed to better model the dihedral torsion angle. • Quantum corrections reveal the existence of novel phenomena considered in subatomic. • Transition rate between the butane conformations is equivalent to chaotic behavior. • Semiquantum torsional dynamics of butane molecule better describes dihedral angle. We study the torsional motion in molecular dynamics using a semiquantal approach. An equivalent potential is proposed to better model the dihedral torsion angle and the ensuing ordinary differential equations are derived for the time evolution of the angular parameters. Through analytical methods of approximation, the system undergoes nonlinear semiquantum dynamics and follows both classical end quantum trajectories with associated sine–Gordon-like effective potential. The ensuing chaotic behavior depicted in the extensive numerical computation artwork, has direct link to the nature of the system. These correspond to the transition rates between cis and trans conformations of real system like n -butane molecule. [ABSTRACT FROM AUTHOR]

• Ab initio parameterization of He, Ne effective potentials in silica was performed. • The solubility of He, Ne in silica was calculated to test the effective potentials. • The solubility calculated values are in good agreement with the experimental data. The article is devoted to the development and testing of He and Ne effective potentials designed for molecular simulation of He and Ne solubility and migration in silicate matrices. The H 12 Si 12 O 30 cage structure, also known as a double-six ring (D6R), was used for ab initio parameterization. Ab initio calculations of the interaction energy between guest He and Ne atoms and the host were performed using the DLPNO CCSD(T) method, which enables correct calculations of the dispersion forces that play an important role in the interaction between dissolved noble gas atoms and the silicate matrix. The physical meaning of effective potentials as well as convergence and uniqueness of the obtained solutions are discussed. The solubility of He and Ne in silica glass over a wide temperature range (260–1500 K) has been calculated to test the effective potentials. The calculated values are in good agreement with the experimental data reported in the literature. [ABSTRACT FROM AUTHOR]

To describe the elastic scattering cross sections of C 12 − 12 C and O 16 − 16 O systems, in our recent work (RM1), the double-folding (DF) model potentials was calculated via the density-dependent averaged effective two-body nucleon-nucleon (NN) interaction (DDAEI). The DDAEI can be generated through the lowest order constrained variational (LOCV) method for the symmetric nuclear matter (SNM), with the input bare Reid68 NN potential. Then the DF potentials were directly inserted into the FRESCO code to find the differential cross-sections (DCS). The result was encouraging with respect to the experimental data and the other theoretical works. In the present report, the above folded potentials are fitted through a Woods-Saxon (WS) shell model potential, which can easily be used (through the WS parameters) as an input to the FRESCO code, without any approximation. The calculated DCS are compared with the corresponding calculations coming from the fitting procedures with the input finite range DDM3Y1-Reid68 potential, RM1 and the available experimental data at different incident energies. As in RM1, it is shown that a reasonable description of scattering data at the low and the medium energies for the elastic scattering of the C 12 − 12 C and O 16 − 16 O systems can be obtained in the framework of the above LOCV-DDAEI, without any need for defining a parameterized density dependent function in the effective NN potential, which is formally considered in the typical DDM3Y1-Reid68 interactions. The χ 2 fits are calculated and discussed. Our result based on DF WS potential parameters, i.e., WS-FRESCO DCS, are approximately in agreement to those of RM1. Finally, the generated energy dependent WS potentials can be directly used in the future calculations and considered as an approximate energy dependent shell model one-body potential which is based on the phenomenological NN interaction. [ABSTRACT FROM AUTHOR]