Vorton existence and stability

We present the first concrete evidence for the classical stability of vortons, circular cosmic string loops stabilized by the angular momentum of the charge and current trapped on the string. We begin by summarizing what is known about vorton solutions and, in particular, their analytic stability with respect to a range of radial and nonradial perturbations. We then discuss numerical results of vorton simulations in a full 3D field theory, that is, Witten's original bosonic superconducting string model with a modified potential term. For specific parameter values, these simulations demonstrate the long-term stability of sufficiently large vorton solutions created with an elliptical initial ansatz.     

Destruction of Fermion Zero Modes on Cosmic Strings

I examine the existence of zero-energy fermionsolutions (zero modes) on cosmic strings in an SO (10)grand unified theory. The current-carrying capability ofa cosmic string formed at one phase transition can be modified at subsequent phasetransitions. I show that the zero modes may be destroyedand the conductivity of the string altered. I discussthe cosmological implications of this, and show that it allows vorton bounds to be relaxed.     

Recent developments in vorton theory

This article provides a concise overview of recent theoretical results concerning the theory of vortons, which are defined to be (centrifugally supported) equilibrium configurations of (current-carrying) cosmic string loops. Following a presentation of the results of work on the dynamical evolution of small circular string loops, whose minimum energy states are the simplest examples of vortons, recent order-of-magnitude estimates of the cosmological density of vortons produced in various kinds of theoretical scenarios are briefly summarized.     

Radiation from cosmic chiral string loops

The gravitational and electromagnetic radiation from chiral superconducting cosmic string loops is calculated. The formulas for energy, momentum, and angular momentum losses due to gravitational and electromagnetic radiation from chiral loops of an arbitrary configuration are derived. After summation over all modes, expressions for the corresponding radiation rates averaged over the loop oscillation period have the form of four-dimensional integrals. These formulas are reduced to sums over the kinks for loops composed of piece-wise linear strings. For three examples of string loops, the total radiation rates are calculated numerically depending on the chiral current along the string. In the limit of a nearly maximum current, which corresponds to a stationary loop (vorton) configuration, we determine the upper bounds on the gravitational and electromagnetic radiation. We also estimate the oscillation damping time of a nearly stationary loop.     

Cosmic Strings in Realistic Particle Physics Theories and Baryogenesis

Grand unified theories can admit cosmic stringswith fermion zero modes. Such zero modes result in thestring being current-carrying and the formation ofstable remnants, vortons. However, the string zero modes do not automatically survive subsequentphase transitions. In this case the vortons dissipate.It is possible that the dissipating cosmic vortonscreate the observed baryon asymmetry of the universe. We show that fermion zero modes are anautomatic consequence cosmic strings in supersymmetrictheories. Since supersymmetry is not observed in nature,we consider possible supersymmetry-breaking terms. Some of these terms result in the zero modesbeing destroyed. We calculate the baryon asymmetrygenerated by the consequent dissipating cosmic vortons.If the supersymmetry-breaking scale is high enough, then the dissipating cosmic vortons couldaccount for the observed baryon asymmetry.     

Primordial black hole formation by stabilized embedded strings in the early universe

Primordial black hole formation by cosmic string collapses is reconsidered in the case where the winding number of the string is larger than unity. The line energy density of a multiple winding string becomes greater than that of a single winding string so that the probability of black hole formation by string collapse during loop oscillation would be strongly enhanced. Moreover, this probability could be affected by changes in gravity theory due to large extra dimensions based on the brane universe model. In addition, a wider class of strings which are stable compared to conventional cosmic strings can contribute to such a scenario. Although the production of the multiple winding defect is suppressed and its number density should be small, the enhancement of black hole formation by the increased energy density may provide a large number of evaporating black holes in the present universe which gives more stringent constraints on the string model compared to the ordinary string scenario.     

Charged and superconducting vortices in dense quark matter

Quark matter at astrophysical densities may contain stable vortices due to the spontaneous breaking of hypercharge symmetry by kaon condensation. We argue that these vortices could be both charged and electrically superconducting. Current carrying loops (vortons) could be long-lived and play a role in the magnetic and transport properties of this matter. We provide a scenario for vorton formation in protoneutron stars.     

Noninertial Effects on a Dirac Neutral Particle Inducing an Analogue of the Landau Quantization in the Cosmic String Spacetime

We discuss the behavior of external fields interacting with a Dirac neutral particle with a permanent electric dipole moment in order to achieve relativistic bound state solutions in a noninertial frame and in the presence of a topological defect spacetime. We show that the noninertial effects of the Fermi?CWalker reference frame induce a radial magnetic field even in the absence of magnetic charges, which is influenced by the topology of the cosmic string spacetime. We then discuss the conditions that the induced fields must satisfy to yield the relativistic bound states corresponding to the Landau?CHe?CMcKellar?CWilkens quantization in the cosmic string spacetime. Finally, we obtain the Dirac spinors for positive-energy solutions and the Gordon decomposition of the Dirac probability current.     

Berry’s phase for a spin 1/2 particle in the presence of topological defects

The relativistic quantum dynamics of a spinorial quantum particle in the presence of a chiral conical background is investigated. We study the gravitational Berry geometric quantum phase acquired by a spin 1/2 particle in the chiral cosmic string spacetime. We obtain the result that this phase depends on the global features of this spacetime. We also consider the case that a string possesses an internal magnetic flux and obtain the geometric quantum phase in this case. The spacetime of multiple chiral cosmic strings is considered and the relativistic Berry quantum phase is also obtained.     

Prescribing topological defects for the coupled Einstein and Abelian Higgs equations

We construct multi-string solutions of the coupled Einstein and Abelian Higgs equations so that the spacetime is uniform along the time axis and a vertical direction and nontrivial geometry is coded on a Riemann surfaceM. We concentrate on the critical Bogomol'nyi phase. WhenM is compact, the Abelian Higgs model is defined by a complex line bundleL overM. We prove that, due to the coupling of the Einstein equations, the Euler characteristic ofM and the first Chern number of the line bundleL identified as the total string number impose an exact obstruction to the existence of a string solution. Such an obstruction leads to some interesting implications. We then study the existence of multi-string solutions which can realize a prescribed string distribution. We show that there are such solutions when the local string winding numbers do not exceed half of the total string number. WhenM is noncompact and globally conformal to a plane, we show that the energy scale of symmetry breaking plays a crucial role and there are finite-energy radially symmetric string solutions realizing a given string number if and only if the symmetry breaking scale is sufficiently small but nonvanishing. Finally, we obtain finite-energy multistring solutions with an arbitrary string distribution and associated local winding numbers. These solutions are not radially symmetric and are regular everywhere and topologically nontrivial so that both the energy of the matter-gauge sector and the energy of the gravitational sector viewed as the total Gauss curvature ofM are quantized.     

Magnetic strings in f(R) gravity

We construct a new class of spinning magnetic string solutions in f(R) gravity with constant scalar curvature. These solutions which produce a longitudinal magnetic field have no curvature singularity and no horizon, but have a conic geometry with a deficit angle. We also generalize this class of solutions to the case of spinning magnetic solutions with one rotation parameter. We find that the spinning string has a net electric charge which is proportional to the rotation parameter. With choosing a suitable counterterm, we remove the divergences of the action. The conserved quantities of the solutions are also calculated by using the counterterm method.     

Superconducting strings

It is known that certain spontaneously broken gauge theories give rise to stable strings or vortex lines. In this paper it is shown that under certain conditions such strings behave like superconducting wires whose passage through astrophysical magnetic fields would generate a variety of striking and perhaps observable effects. The superconducting charge carriers may be either bosons (if a charged Higgs field has an expectation value in the core of the string) or fermions (if charged fermions are trapped in zero modes along the string, as is known to occur in certain circumstances). They might be observable as synchrotron sources or as sources of high-energy cosmic rays. If the charge carriers are ordinary quarks and leptons, the strings have important baryon number violating interactions with magnetic fields; such a string, traversing a galactic magnetic field of 10^?6 G, creates baryons (or antibaryons) at a rate of order 10¹² particles/cm of string per second.     

Magnetic dilaton strings in anti-de Sitter spaces

With an appropriate combination of three Liouville-type dilaton potentials, we construct a new class of spinning magnetic dilaton string solutions which produces a longitudinal magnetic field in the background of anti-de Sitter spacetime. These solutions have no curvature singularity and no horizon, but have a conic geometry. We find that the spinning string has a net electric charge which is proportional to the rotation parameter. We present the suitable counterterm which removes the divergences of the action in the presence of dilaton potential. We also calculate the conserved quantities of the solutions by using the counterterm method.     

Ratios of magnetic charge to charge and of magnetic mass to mass

It is shown that, unlike the case of (vacuum) solutions describing isolated bodies, conformal Killing fields are not excluded by the structure of vacuum gravitational magnetic monopoles at null infinity. The resulting dilation must be constant. This brings support to the viewpoint that such solutions might have a role to play in the understanding of gravitational entropy and time's arrow. If, in addition, a Maxwellian magnetic monopole (Dirac string singularity) is available, the ratio of the total magnetic charge (magnetic mass) over the total electric charge (mass) can be identified. This common feature between the gravitational and the electromagnetic interaction finds its origin in the space-time topology.     

Magnetic Dilaton Rotating Strings in the Presence of Exponential Nonlinear Electrodynamics

In this paper, we construct a new class of four-dimensional spinning magnetic dilaton string solutions which produces a longitudinal nonlinear electromagnetic field. The Lagrangian of the matter field has the exponential form. We study the physical properties of the solution in ample details. Geometrical, causal and geodisical structures of the solutions are investigated, separately. We confirm that the spacetime is both null and geodesically complete. We find that these solutions have no curvature singularity and no horizon, but have a conic geometry. We investigate the effects of variation of charge and the intensity of the dilaton field, on the deficit angle. Due to the presence of the dilaton field, the asymptotic behavior of the solutions are neither flat nor (anti-) de Sitter [(A)dS]. Furthermore, we extend our study to the higher dimensions and obtain the (n+1)-dimensional magnetic rotating dilaton strings with k≤[n/2] rotation parameters and calculate conserved quantities of the solutions. Although these solutions are not asymptotically (A)dS, we use counterterm method to calculate conserved quantities. We also calculate electric charge and show that the net electric charge of the spinning string is proportional to the rotating parameter and the electric field only exists when the rotation parameter does not vanish.     

STATICAL SPHEROSYMMETRICAL SOURCELESS SOLUTION OF SU(2) GAUGE FIELD——THE SELFDUALITY,UNIQUENESS AND THE SELF INDUCED CHARGE CURRENT

It is shown that the statical spherosymmetrical sourceless solutions of SU(2) guagefield,which satisfy a physical boundary condition,must be selfdual.Then from theselfdual condition,we solve the equation explicitily,hence show the uniqueness analy-tically.By gauge transforming the Lagrangian by a local generator of synchrono-symmetry,we get a corresponding local charge current density,which is both gaugeinvariant and conserved.The total values of either electric or magnetic charge arequantized,but the charge distributions in space are continuous and not restrictedby quantization.Finally we discuss a mechanism of spontaneous symmetry break-down.Contrary to ordinary magnetic flux string,now the ordered phase is surround-ed by the normal phase,the ordered phase repels electric fields,and electric fieldsdestory the ordered phase.     

Configurations of SO(3) monopoles with multiple magnetic charge

In this paper we consider configurations of monopoles with multiple magnetic charge in nonabelian gauge theory. Explicit gauge transformations are constructed which eliminate the string singularities for single monopoles of multiple magnetic charge, and for an arbitrary number of monopoles lying along a line. The question of finding nonsingular solutions is discussed.     

Abelian cosmic string in the extended Starobinsky model of gravity

We analyze numerically the behaviour of the solutions corresponding to an Abelian cosmic string taking into account an extension of the Starobinsky model, where the action of general relativity is replaced by \(f(R) = R - 2\Lambda + \eta R^2 + \rho R^m\), with \(m > 2\). As an interesting result, we find that the angular deficit which characterizes the cosmic string decreases as the parameters \(\eta \) and \(\rho \) increase. We also find that the cosmic horizon due to the presence of a cosmological constant is affected in such a way that it can grows or shrinks, depending on the vacuum expectation value of the scalar field and on the value of the cosmological constant.     

Chiral magnetic wave at finite baryon density and the electric quadrupole moment of the quark-gluon plasma

The chiral magnetic wave is a gapless collective excitation of quark-gluon plasma in the presence of an external magnetic field that stems from the interplay of chiral magnetic and chiral separation effects; it is composed of the waves of the electric and chiral charge densities coupled by the axial anomaly. We consider a chiral magnetic wave at finite baryon density and find that it induces the electric quadrupole moment of the quark-gluon plasma produced in heavy ion collisions: the "poles" of the produced fireball (pointing outside of the reaction plane) acquire additional positive electric charge, and the "equator" acquires additional negative charge. We point out that this electric quadrupole deformation lifts the degeneracy between the elliptic flows of positive and negative pions leading to v(2)(π(+))相似文献   

Self-force on an electric dipole in the spacetime of a cosmic string

We calculate the electrostatic self-force on an electric dipole in the spacetime generated by a static, thin, infinite and straight cosmic string. The electric dipole is held fixed in different configurations, namely, parallel, perpendicular to the cosmic string and oriented along the azimuthal direction around this topological defect, which is stretched along the z$z$ axis. We show that the self-force is equivalent to an interaction of the electric dipole with an effective dipole moment which depends on the linear mass density of the cosmic string and on the configuration. The plots of the self-forces as functions of the parameter which determines the angular deficit of the cosmic string are shown for those different configurations.