Singularity formation in general relativistic dynamics of homogeneous scalar fields

Collapsing dynamics of a wide class of self-interacting, self-gravitating homogeneous scalar field models is analyzed. The assumptions made on the potential satisfy some general conditions allowing to show that the generic evolution is divergent in a finite time. Combining results shown here with the ones from [R. Giambó, F. Giannoni, G. Magli, J. Math. Phys. 49 (2008) 042504], dealing with sub-exponential growing potentials, allows us to obtain the same results of singularity formation for more general potentials. Moreover it turns out that these models can be completed to find radiating collapsing star models of the Vaidya type, where blackholes are generically formed.     

Braneworld models of scalar fields with generalized dynamics

This work deals with braneworld models driven by real scalar fields with nonstandard dynamics. We develop the first-order formalism for models with standard gravity but with the scalar fields having generalized dynamics. We illustrate the results with examples of current interest, and we find analytical and numerical solutions for warp factors and scalar fields. The results indicate that the generalized braneworld scenario is classically stable, and capable of localizing gravity.     

Nonequilibrium dynamics of scalar fields in a thermal bath

We study the approach to equilibrium for a scalar field which is coupled to a large thermal bath. Our analysis of the initial value problem is based on Kadanoff-Baym equations which are shown to be equivalent to a stochastic Langevin equation. The interaction with the thermal bath generates a temperature-dependent spectral density, either through decay and inverse decay processes or via Landau damping. In equilibrium, energy density and pressure are determined by the Bose-Einstein distribution function evaluated at a complex quasi-particle pole. The time evolution of the statistical propagator is compared with solutions of the Boltzmann equations for particles as well as quasi-particles. The dependence on initial conditions and the range of validity of the Boltzmann approximation are determined.     

Zero-mass scalar and electrostatic fields with the central symmetry in the general relativity

All asymptotically flat space solutions of Einstein equations with energy-momentum tensor of electrostatic and zero-mass scalar static central symmetric fields as a source were found. There are five branches of general solution; only two of them are contained in previous Penney's solution. In a limit of pure electrostatic field and pure scalar field our solutions become identical with corresponding solutions known previously.     

Self-interacting scalar fields with geometrical interpretations

The idea is advanced that particles arise as distortions of a reimannian background and that such distortions represent particular conformally flat solutions of the “cosmological” Einstein equations with extremely large “cosmological” constants. Particle interactions then appear as gravitational in origin. The idea is illustrated with the help of two scalar models. In the first one the “De Sitter” space can be interpreted as a relativistic field whose ground state undergoes a transition from degenerate to nondegenerate for the critical value of some parameter. In the second one a deeper understanding is reached of the role of the “De Sitter” space in confinement problems and of the nature of the ensemble of vacuum states recently introduced in conformally invariant field theories by Fubini.     

Necessity of mixed kinetic term in the description of general system with identical scalar fields

Most general renormalizable interaction in the system with a set of scalar fields having identical quantum numbers generates naturally mixed kinetic terms in the Lagrangian. Taking into account these terms leads to modification both the renormalization group equations and the tree level analysis as compare with many published results. We obtain conditions for non-appearance of such a running mixing in some important cases.     

No scalar hair behaviors of static massive scalar fields with nodes

The European Physical Journal C - We present a C++ software package called PhaseTracer for mapping out cosmological phases, and potential transitions between them, for Standard Model extensions...     

Constructing networks of defects with scalar fields

We propose a new way to build networks of defects. The idea takes advantage of the deformation procedure recently employed to describe defect structures, which we use to construct networks, spread from small rudimentary networks that appear in simple models of scalar fields.     

Cosmological twinlike models with multi scalar fields

In this study, we consider cosmological models driven by several canonical or noncanonical scalar fields, and we show the manner in which twinlike models for a canonical model can be constructed from noncanonical ones using the superpotential method. We conclude that it is possible to construct twinlike models for multifield cosmological models, even with a nonzero spatial curvature.This work extends the discussions of [D. Bazeia, and J. D. Dantas, Phys. Rev. D 85, 067303(2012)] to cases with multi scalar fields and with non-vanished spatial curvature, by using a different superpotential method.     

Color dielectric model with two scalar fields

SU(2) Yang-Mills theory coupled in a non-minimal way to two scalar fields is discussed. For the massless scalar fields a family of finite energy solutions generated by an external, static electric charge is found. Additionally, there is a single solution which can be interpreted as a confining one. Similar solutions have been obtained in the magnetic sector. In the case of massive scalar fields the Coulomb problem is investigated. We find that asymptotic behavior of the fields can also, for some values of the parameters of the model, give confinement of the electric charge. Quite interestingly one glueball-meson coupling gives the linear confining potential. Finally, it is shown how, for one non-dynamical scalar field, we can derive the color dielectric generalization of the Pagels-Tomboulis model.Received: 22 April 2003, Published online: 12 September 2003     

Five-dimensional cosmological models with massless scalar fields

Simple cosmologies are constructed from solutions of the five-dimensional Einstein equations with a real massless non-self-interacting scalar field source. It is demonstrated that non-trivial cosmological models occur only if the metric of the homogeneous and isotropic three-space of the universe has non-positive constant curvature. For the case of flat three-space, it is further demonstrated that two classes of solutions result - one of which has a power-law type of expansion for three-space and contraction of the one-dimensional internal space, while the other class has an exponential expansion for three-space and exponential contraction of the internal space. The exponentially expanding solutions are the limiting case of the power-law expanding solutions. Hence, our model is consistent with a simple inflationary scenario.     

Nuclear matter calculations with mean scalar fields

We examine the possibility that nuclear-matter binding energy comes from the coupling of nucleons to a mean scalar field; vector fields are simulated by Yukawa potentials. It is found that the mean Schwinger σ field cannot explain the normal nuclear-matter saturation for any values of the coupling constants, while a simple scalar field with only quadratic terms is permitted.     

Group classification of scalar fields with potential interaction

A system of scalar fields with Lagrangian L=(1/2)u_,iu^,i + V(u) in multi-dimensional space—time is considered. The structure of the permissible Lie group is studied for an arbitrary field multiplet. A complete group classification of field doublets and triplets is presented. All conservative fluxes of these systems are calculated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 116–121, March, 1995.     

Self-interacting scalar fields at high-temperature

We study two self-interacting scalar field theories in their high-temperature limit using path integrals on a lattice. We first discuss the formalism and recover known potentials to validate the method. We then discuss how these theories can model, in the high-temperature limit, the strong interaction and General Relativity. For the strong interaction, the model recovers the known phenomenology of the nearly static regime of heavy quarkonia. The model also exposes a possible origin for the emergence of the confinement scale from the approximately conformal Lagrangian. Aside from such possible insights, the main purpose of addressing the strong interaction here – given that more sophisticated approaches already exist – is mostly to further verify the pertinence of the model in the more complex case of General Relativity for which non-perturbative methods are not as developed. The results have important implications on the nature of Dark Matter. In particular, non-perturbative effects naturally provide flat rotation curves for disk galaxies, without need for non-baryonic matter, and explain as well other observations involving Dark Matter such as cluster dynamics or the dark mass of elliptical galaxies.     

Super-higgs effect in supergravity with general scalar interactions

Using the recently established tensor calculus for supergravity, we construct the most general action for the scalar multiplet coupling. We discuss under which conditions supersymmetry is broken spontaneously and show explicitly that the gravitino acquires a mass by absorbing the Goldstone fermion. Parity violation as well as a cosmological constant can be avoided.     

A plane symmetric solution of Einstein's field equations of general relativity containing zero-rest-mass scalar fields

An exact static solution of Einstein's field equations of general relativity in the presence of zero-rest-mass scalar fields has been obtained when both the metric tensor gijand the zero-rest-mass scalar field φexhibit plane symmetry in the sense of Taub [9]. Our solution generalizes the empty space-time solution with plane symmetry previously obtained by Taub to the situation when static zero-rest-mass scalar fields are present. The static plane symmetric solutoins of Einstein's field equations in the presence of massive scalar fields, and the difference between the massless and non-massless scalar fields are being investigated, and will be published separately later on. We also hope to discuss non-static plane symmetric solutions of Einstein's field equations in the presence of scalar fields in future.