Superconducting string texture

Abstract

We present a detailed analytical and numerical study of a novel type of static, superconducting, classically stable string texture in a renormalizable topologically trivial massive U(1) gauge model with one charged and one neutral scalar. An upper bound on the mass of the charged scalar as well as on the current that the string can carry are established. A preliminary unsuccessful search for stable solutions corresponding to large superconducting loops is also reported.The term texture is attributed generically to topological configurations trivial at spatial infinity. The winding of the fields takes place over a finite region which roughly defines the location of the configuration. Such defects have attracted considerable attention, both in particle physics and cosmology. Well known examples are the Skyrmion which offers a useful alternative description of the nucleon, and the global texture used recently to implement an appealing mechanism for structure formation in the Universe. In cosmological applications one makes use of the instability of three dimensional texture in renormalizable purely scalar theories. All such configurations are unstable towards shrinking; they collapse to a point and eventually decay to scalar radiation. This is a natural decay mechanism, which on the one hand prevents the domination of the energy density by texture-like defects, and on the other it leads to highly energetic events, which can provide the primordial fluctuations necessary for structure formation.In particle physics one would be more interested in observing such solitons in accelerator experiments, and the above instability is an unwanted feature. One approach to stabilize such configurations was the introduction into the action of higher derivative terms. However, being nonrenormalizale, such terms are undesirable in the tree level action, and furthermore it has not been possible so far to produce in a controllable unambiguous way a quartic term of the right sign to lead to stable solitons. An alternative way has been advocated recently and has succesfully stabilized texture in realistic extensions of the standard model with more than the minimal one Higgs doublet content. The texture here is stabilized by the gauge interactions.An extended Higgs sector in the effective low energy theory of electroweak interactions is favored by supersymmetry, superstring theory and is necessary if one wishes to arrange for an efficient and potentially realistic electroweak baryogenesis. Examples of simple realistic models with a multiple Higgs field content are the two Higgs-doublet standard model ͑2HSM͒, and the minimal supersymmetric standard model ͑MSSM͒. It is well known that no finite energy topological strings or particle-like solitons exist in these models, and furthermore if no additional spontaneously broken discrete global symmetries are introduced, they do not carry domain walls either.However, it was pointed out recently ͓1͔ that an extended Higgs sector supports generically the existence of a new class of quasi-topologica...

On vortices and rings in extended Abelian models

“…These string loops are examined in [18] but in the framework of a U (1) × U (1) model, where the existence of the defect is ensured for topological reasons [19,23]. That model, is a continuation of previous work [8][9][10]. In the second part of this paper, we examine a modified version of the model in [18].…”

“…In [8][9][10], work on classically stable, metastable quasi-topological domain walls and strings in simple topologically trivial models, as well as in the 2HSM, has been done. These solutions are local minima of the energy functional and can quantum E-mail address: csath@physics.uoc.gr.…”

Scalar-tensor quintessence with a linear potential: Avoiding the big crunch cosmic doomsday

“…Quintessence models where the potential takes negative values for a range of scalar field values are generic in a variety of theoretical models including N = 2, 4, 8 gauged supergravity [1,2], brane cosmology [3] and cyclic universe models [4,5]. The cosmological evolution in models involving such potentials has been studied extensively in the context of General Relativity [6][7][8][9][10].…”

“…It is well known that quintessence models with scalar field potentials that get negative for a range of field values generically predict the collapse of the cosmic scale factor to a Big Crunch singularity [6][7][8][9][10] at a future cosmological time (cosmic doomsday). This collapse is due to the eventual scalar field evolution towards negative values of its potential where the gravity of the field is attractive.…”

“…This collapse is due to the eventual scalar field evolution towards negative values of its potential where the gravity of the field is attractive. Such a behavior is generic for all quintessence models where the scalar field potential is not strictly positive but it has been studied for monotonic linear potentials of the form [6][7][8][9][10]…”