arXiv subjects

Theodora Ioannidou

Publications and source records attributed to Theodora Ioannidou.

At least 37 records · Page 2Linked to original sources

arXiv2005

Non-BPS Black holes in N=4 Supersymmetric Yang-Mills Theory Coupled to Gravity

We construct non-BPS regular and black hole solutions of N=4 SU(N) supersymmetric Yang-Mills theory coupled to Einstein gravity. Our numerical studies reveal a number of interesting phenomena when the gravitational constant $α=M_{YM}/gM_{Planck}$ (where $M_{Planck}$ is the Planck mass and $M_{YM}$ is the monopole mass) is either weak (flat limit) or comparable to the Yang-Mills interaction. In fact, black hole solutions exist in a certain bounded domain in the $(α, r_H)$ plane where $r_H$ denotes the radius of the black

hep-th↗

arXiv2004

Axially symmetric SU(3) Gravitating Skyrmions

Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [1]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail.

gr-qc↗

arXiv2004

SU(5) Gravitating Monopoles

Spherically symmetric solutions of the SU(5) Einstein-Yang-Mills-Higgs system are constructed using the harmonic map ansatz \cite{IS}. This way the problem reduces to solving a set of ordinary differential equations for the appropriate profile functions.

hep-th↗

arXiv2004

An Improved Harmonic Map Ansatz

The rational map ansatz of Houghton et al \cite{HMS} is generalised by allowing the profile function, usually a function of $r$, to depend also on $z$ and $\bar{z}$. It is shown that, within this ansatz, the energies of the lowest $B=2,3,4$ field configurations of the SU(2) Skyrme model are closer to the corresponding values of the true solutions of the model than those obtained within the original rational map ansatz. In particular, we present plots of the profile functions which do exhibit their dependence on $ z$ and $\bar{z}$. The obvious generalisation of the ansatz to higher SU(N) models involving the introduction of more projectors is briefly mentioned.

hep-th↗

arXiv2003

Gravitating SU(N) Monopoles from Harmonic maps

Spherically symmetric solutions of the SU(N) Einstein-Yang-Mills-Higgs system are constructed using the harmonic map ansatz. The problem reduces to solving a set of ordinary differential equations for the appropriate profile functions. In the SU(2) case, we recover the equations studied in great detail previously, while for the SU(N) (N > 2) case we find new solutions. In the SU(3) case we see that our expressions are the gravitating analogues of the solutions obtained through the SO(3) embedding into SU(2).

hep-th↗

arXiv2003

Non-trivial Soliton Scattering in Planar Integrable Systems

The behavior of solitons in integrable theories is strongly constrained by the integrability of the theory, that is by the existence of an infinite number of conserved quantities that these theories are known to possess. As a result the soliton scattering of such theories are expected to be trivial (with no change of direction, velocity or shape). In this paper we present an extended review on soliton scattering of two spatial dimensional integrable systems which have been derived as dimensional reductions of the self-dual Yang-Mills-Higgs equations and whose scattering properties are highly non-trivial.

hep-th↗

arXiv2003

On the Q-ball Profile Function

We use analytic and numerical methods to obtain the solution of the Q-ball equation of motion. In particular, we show that the profile function of the three-dimensional Q-ball can be accurately approximated by the symmetrized Woods-Saxon distribution.

hep-th↗

arXiv2002

Bogomolny Yang-Mills-Higgs Solutions in (2+1) anti-de Sitter Space

This paper investigates an integrable system which is related to hyperbolic monopoles; ie the Bogomolny Yang-Mills-Higgs equations in (2+1) anti-de Sitter space which are integrable and whose solutions can be obtained using analytical methods. In particular, families of soliton solutions have been constructed explicitly and their dynamics has been investigated in some detail.

hep-th↗

arXiv2001

Soliton dynamics in 3D ferromagnets

We study the dynamics of solitons in a Landau-Lifshitz equation describing the magnetization of a three-dimensional ferromagnet with an easy axis anisotropy. We numerically compute the energy dispersion relation and the structure of moving solitons, using a constrained minimization algorithm. We compare the results with those obtained using an approximate form for the moving soliton, valid in the small momentum limit. We also study the interaction and scattering of two solitons, through a numerical simulation of the (3+1)-dimensional equations of motion. We find that the force between two solitons can be either attractive or repulsive depending on their relative internal phase and that in a collision two solitons can form an unstable oscillating loop of magnons.

cond-mat↗

arXiv2000

SU(N) Skyrmions from Instantons

Atiyah and Manton have outlined a scheme to obtain approximations to the SU(2) skyrmions from instantons in $\R^4$. In this paper we apply this scheme to construct, in an explicit form, approximations to static spherically symmetric SU(N) skyrmions with various baryon numbers. In particular we show how to obtain the skyrmions from instantons using harmonic maps into complex projective spaces.

hep-th↗

arXiv1999

Non-BPS Dirac-Born-Infeld Solitons

We show that CPn sigma model solitons solve the field equations of a Dirac-Born-Infeld (DBI) action and, furthermore, we prove that the non-BPS soliton/anti-soliton solutions of the sigma model also solve the DBI equations. Using the moduli space approximation we compare the dynamics of the BPS sigma model solitons with that of the associated DBI solitons. We find that for the CP1 case the metric on the moduli space of sigma model solitons is identical to that of the moduli space of DBI solitons, but for CPn with n>1 we show that the two metrics are not equal. We also consider the possibility of similar non-BPS solitons in other DBI theories.

hep-th↗

arXiv1999

Monopoles and Harmonic Maps

Recently Jarvis has proved a correspondence between SU(N) monopoles and rational maps of the Riemann sphere into flag manifolds. Furthermore, he has outlined a construction to obtain the monopole fields from the rational map. In this paper we examine this construction in some detail and provide explicit examples for spherically symmetric SU(N) monopoles with various symmetry breakings. In particular we show how to obtain these monopoles from harmonic maps into complex projective spaces. The approach extends in a natural way to monopoles in hyperbolic space and we use it to construct new spherically symmetric SU(N) hyperbolic monopoles.

hep-th↗

arXiv1999

Non-BPS String Junctions and Dyons in N=4 Super-Yang-Mills

We construct non-BPS dyon solutions of N=4 SU(n) supersymmetric Yang-Mills theory. These solutions are the worldvolume solitons which describe non-BPS Type IIB non-planar string junctions connecting n parallel D3-branes. The solutions are smooth deformations of the 1/4 BPS states which describe planar string junctions.

hep-th↗

arXiv1999

Non-Bogomolny SU(N) BPS Monopoles

For N>2 we present static monopole solutions of the second order SU(N) BPS Yang-Mills-Higgs equations which are not solutions of the first order Bogomolny equations. These spherically symmetric solutions may be interpreted as monopole anti-monopole configurations and their construction involves harmonic maps into complex projective spaces.

hep-th↗

arXiv1999

Monopoles from Rational Maps

The moduli space of charge k SU(2) BPS monopoles is diffeomorphic to the moduli space of degree k rational maps between Riemann spheres. In this note we describe a numerical algorithm to compute the monopole fields and energy density from the rational map. The results for some symmetric examples are presented.

hep-th↗

arXiv1998

Lagrangian Formulation of the General Modified Chiral Model

We present a Lagrangian formulation for the general modified chiral model. We use it to discuss the Hamiltonian formalism for this model and to derive the commutation relations for the chiral field. We look at some explicit examples and show that the Hamiltonian, containing a contribution involving a Wess-Zumino term, is conserved, as required.

hep-th↗

arXiv1998

A Note on Ward's Chiral Model

A one parameter generalization of Ward's chiral model in 2+1 dimensions is given. Like the original model the present one is integrable and possesses a positive-definite and conserved energy and $y$-momentum. The details of the scattering depend on the value of the parameter of the generalisation.

hep-th↗

arXiv1998

Solutions of the Modified Chiral Model in (2+1) Dimensions

This paper deals with classical solutions of the modified chiral model on $R^{2+1}$. Such solutions are shown to correspond to products of various factor which we call time-dependent unitons. Then the problem of solving the system of second-order partial differential equations for the chiral field is reduced to solving a sequence of systems of first-order partial differential equations for the unitons.

hep-th↗