A comparison of phantom linear scalar field and non-linear Born-Infeld scalar field

This paper studies phantom linear scalar field （LSF） and phantom non-linear Born-Infeld （NLBI） scalar field with square potential of the form V（Ф） =1/2m^2Ф^2. The equation of state parameter w（z）, and evolution of scale factor a（t） in both phantom LSF and phantom NLBI scalar model are explored. The age of universe Hot and the transition redshift Z are obtained. The Gold data set of 157-SN-Ia is used to constrain parameters of the two models by numerical calculation. The phantom LSF is slightly better than the phantom NLBI type scalar field model for a large m. Although a smaller m corresponding to a slower rolling of field Ф better fits the observation data, the difference between phantom NLBI scalar field and phantom LSF is not distinct in this case.

Real scalar field scattering in the nearly extremal Schwarzschild de Sitter space

Reasonable approximations are introduced to investigate the real scalar field scattering in the nearly extremal Schwarzschild-de Sitter （SdS） space. The approximations naturally lead to the invertible x（r） and the global replacement of the true potential by a PSshl-Teller one. Meanwhile, the Schr6dinger-like wave equation is transformed into a solvable form. Our numerical solutions to the wave equation show that the wave is characteristically similar to the harmonic under the tortoise coordinate x, while the wave piles up near the two horizons and the wavelength tends to its maximum as the potential approaches to the peak under the radial coordinate τ.

Real scalar field scattering with polynomial approximation around Schwarzschild–de Sitter black-hole

As one of the fitting methods, the polynomial approximation is effective to process sophisticated problem. In this paper, we employ this approach to handle the scattering of scalar field around the Schwarzschild-de Sitter blackhole. The complicated relationship between tortoise coordinate and radial coordinate is replaced by the approximate polynomial. The Schroedinger-like equation, the real boundary conditions and the polynomial approximation construct a full Sturm Liouville type problem. Then this boundary value problem can be solved numerically for two limiting cases： the first one is the Nariai black-hole whose horizons are close to each other, the second one is the black-hole with the horizons widely separated. Compared with previous results （Brevik and Tian）, the field near the event horizon and cosmological horizon can have a better description.

Effects of Interaction Between Gravitation and Nonlinear Electrodynamics On Scalar Field Evolution

In this paper we investigate the scalar field evolution in the dyadosphere spacetime by using the third-order WKB approximation. We find that the coupling term between the gravitation and the nonlinear electrodynamics makes the scalar field decay more quickly and it also makes the scalar field oscillate more slowly. On the o＇ther words, this coupling term takes effect on the scalar field evolution as a damping factor. At the same time these effects become more obvious for the scalar field with higher angle quantum number.

GFFD： Generalized free-form deformation with scalar fields

The novel free-form deformation (FFD) technique presented in the paper uses scalar fields definedby skeletons with arbitrary topology. The technique embeds objects into the scalar field by assigning a field value to each point of the objects. When the space of the skeleton is changed, the distribution of the scalar field changes accordingly, which implicitly defines a deformation of the space. The generality of skeletons assures that the technique can freely define deformable regions to produce a broader range of shape deformations.

STUDY OF EXPLICIT ANALYTIC SOLUTIONS FOR THE NONLINEAR COUPLED SCALAR FIELD EQUATIONS

By using two different transformations, several types of exact analytic solutions for a class of nonlinear coupled scalar field equation are obtained, which contain soliton solutions, singular solitary wave solutions and triangle function solutions. These results can be applied to other nonlinear equations. In addition, parts of conclusions in some references are corrected.

Resonant frequencies of massless scalar field in rotating black-brane spacetime

This paper investigates the resonant frequencies of the massless scalar field in the near extremal Kerr-like black-brane spacetime. It is shown that the different angular quantum number will present different resonant frequencies. It is also shown that the real part of the resonant frequencies increases as the compact dimensions parameter μi increases, but the magnitude of the imaginary part decreases as μi increases.

Casimir Effect of Massive Scalar Field with Hybrid Boundary Condition in(1+1)-Dimensional Spacetime

The Casimir energy of massive scalar field with hybrid （Diriehlet-Neumann） boundary condition is calculated. In order to regularize the model, the typical methods named as mode summation method and Green＇s function method are used respectively. It is found that the regularized zero-point energy density depends on the scalar field＇s mass. When the field is massless, the result is consistent with previous literatures.

Complex frequencies of a massless scalar field in loop quantum black hole spacetime

Recently, considerable progress has been made in understanding the early universe by loop quantum cosmology. Modesto et al. investigated the loop quantum black hole （LQBH）using improved semiclassical analysis and they found that the LQBH has two horizons, an event horizon and a Cauchy horizon, just like the Reissner-NordstrSm black hole. This paper focuses on the dynamical evolution of a massless scalar wave in the LQBH background. By investigating the relation between the complex frequencies of the massless scalar field and the LQBH parameters using the numerical method, we find that the polymeric parameter P makes the massless scalar field decay more quickly and makes the ground scalar wave oscillate slowly. However, the polymeric parameter P causes the frequency of the high harmonic massless scalar wave to shift according to its value. We also find that the loop quantum gravity area gap parameter a0 causes the massless scalar field to decay more slowly and makes the period of the massless scalar field wave become longer. In the complex ω plane, the frequency curves move counterclockwise when the polymeric parameter P increases and this spiral effect is more obvious for a higher harmonic scalar wave.

Numerical Solution of Scalar Field for Nariai Case in 5D Ricci-Flat SdS Black String Space with Polynomial Approximation

As one exact candidate of the higher dimensional black hole, the 5D Ricci-flat Schwarzsehild-de Sitter black string space presents something interesting. In this paper, we give a numerical solution to the real scalar field around the Nariai black hole by the polynomial approximation. Unlike the previous tangent approximation, this fitting function makes a perfect match in the leading intermediate region and gives a good description near both the event and the cosmological horizons. We can read from our results that the wave is close to a harmonic one with the tortoise coordinate. Furthermore, with the actual radial coordinate the waves pile up almost equally near the both horizons.

Hawking Radiation from Spherically Symmetrical Gravitational Collapse to an Extremal R-N Black Hole for a Charged Scalar Field

Si-Jie Gao has recently investigated Hawking radiation from spherically symmetrical gravitational collapse to an extremal R-N black hole for a real scalar field. Especially he estimated the upper bound for the expected number of particles in any wave packet belonging to spontaneously produced from the state , which confirms the traditional belief that extremal black holes do not radiate particles. Making some modifications, we demonstrate that the analysis can go through for a charged scalar field.

Novel Localized Excitations of Nonlinear Coupled Scalar Fields

Some extended solution mapping relations of the nonlinear coupled scalar field and the well-known φ^4 model are presented. Simultaneously, inspired by the new solutions of the famous φ^4 model recently proposed by Jia, Huang and Lou, five kinds of new localized excitations of the nonlinear coupled scaiar field （NCSF） system are obtained.

Examining a Fifth Force Application by Using Dilaton Model and Padmanabhan Inflaton Scalar Field in Early Universe to Generate GW and Gravitons

On page 17 of a book on Modified Gravity by Li and Koyama, there is a discussion of how to obtain a Fifth force by an allegedly non-relativistic approximation with a force proportional to minus the spatial derivative of a scalar field. If the scalar field says for an inflaton, as presented by Padmanabhan only depends upon time, of course, this means that no scalar field contributing to a fifth force our proposal in the neighborhood of Planck time is to turn the time into being equal to r/[constant times c]. This is in the neighborhood of Planck time. Then having done that, consider the initially Plank regime inflaton field as being spatially varying and from there apply a fifth force as a way to help initiate black hole production and possibly Gravitons.

Exact Static Plane Symmetric Soliton-Like Solutions to the Nonlinear Interacting Electromagnetic and Scalar Field Equations in General Relativity

This research work is related to soliton solutions considered as models that can describe the complex configuration of elementary particles from the study of the interactions of their fields. It is interested in the interaction of fields between two different elementary particles by expressing their physical properties. For that, we have obtained, exact static plane symmetric soliton-like solutions to the nonlinear equations of interacting electromagnetic and scalar fields taking into account the own gravitational field of elementary particles using the calibrated invariance function P(I). It has been proved that all solutions of the Einstein, nonlinear electromagnetic and scalar field equations are regular with the localized energy density. Moreover, the total charge of particles is finite and the total energy of the interaction fields is bounded. It have been emphasized the importance to the own gravitational field of elementary particles and the role of the nonlinearity of fields in the determination of these solutions. In flat space-time, soliton-like solutions exist but the total energy of the interaction fields is equal to zero. We have also shown that in the linear case, soliton-like solutions are absent.

Noise-Induced Origin of the Fundamental Scalar Field

The physical nature of the fundamental scalar field generation and hence the origination of the Universe is a matter of the discussions for many years. We propose to use the statistical approach to the description of the steady states of the quasi stationary systems with the elements of the quantum field theory methods as a basis to explain the appearance of the cosmological scalar field. Particularly, we apply two fundamental principles, i.e., the H-theorem and least-energy principle to show principal possibility of the scalar field origination. Along with the basic statement that in the presence of the fundamental scalar field, the energy of the vacuum ground state is lower than the ground state energy of the vacuum with no scalar field (primary vacuum), and with regard to the nonlinear interaction of fluctuating physical fields with the scalar field, these principles are employed to reveal probable phase transitions that may be associated with origin and further evolution of the Universe. Thus, we propose the possible physical justification of the spontaneous cosmological scalar field generation.

Dynamic of Scalar Bosons in Aharonov-Bohm Magnetic Field

We study the dynamic of scalar bosons in the presence of Aharonov-Bohm magnetic field. First, we give the differential equation that governs this dynamic. Secondly, we use variational techniques to show that the following Schrödinger-Newton equation: , where A is an Aharonov-Bohm magnetic potential, has a unique ground-state solution.

Gauging universe expansion via scalar fields

In this study,we investigate the expansion of the FRLW universe in the open,closed,and flat geometries.The universe is dominated by a scalar field(spatially homogeneous)as a source of dark energy.We consider the three different classes of scalar fields-quintessence,tachyonic,and phantom field-for our analysis.A mathematical analysis is carried out by considering these three scalar fields with exponential and power-law potentials.Both potentials give exponential expansion in the open,closed,and flat FRLW universes.It is found that quintessence,tachyonic,and phantom scalar fields are indistinguishable under the slow roll approximation.

Interacting tachyonic scalar field

We discuss the coupling between dark energy and matter by considering a homogeneous tachyonic scalar field as a candidate for dark energy.We obtained the functional form of scale factor by assuming that the coupling strength depends linearly on the Hubble parameter and energy density.We also estimated the cosmic age of the Universe for different values of coupling constant.

On Scalar Planck Waves

The sound of space-time at the large scale is observed in the form of gravitational waves, which are disturbances in space-time produced by wavelike distortions (or kinks) in the gravitational field of an accelerating parcel or distribution of energy. In this study, we investigate a hypothetical wave mode of quantum space-time, which suggests the existence of scalar Planck waves. According to this hypothesis, the sound of quantum space-time corresponds to kinks propagating in the gravitational displacement field of an oscillating energy density. In evaluating the emission of scalar Planck waves and their effect on the geometry of space-time, one finds that they not only transport a vanishingly small amount of energy but can also be used to simulate gravity.

Weak cosmic censorship conjecture in BTZ black holes with scalar fields

The weak cosmic censorship conjecture in the near-extremal BTZ black hole has been tested using test particles and fields.It has been claimed that such a black hole can be overspun.In this paper,we review the thermodynamics and weak cosmic censorship conjecture in BTZ black holes using the scattering of a scalar field.The first law of thermodynamics in the non-extremal BTZ black hole is recovered.For the extremal and near-extremal black holes,due to the divergence of the variation of entropy,we test the weak cosmic censorship conjecture by evaluating the minimum of the function f,and find that both the extremal and near-extremal black holes cannot be overspun.