|
In quantum field theory, a non-topological soliton (NTS) is a field configuration possessing, contrary to a topological one, a conserved Noether charge and stable against transformation into usual particles of this field for the following reason. For fixed charge ''Q'', the mass sum of ''Q'' free particles exceeds the energy (mass) of the NTS so that the latter is energetically favorable to exist. The interior region of an NTS is occupied by vacuum different from surrounding one. Thus a surface of the NTS represents a domain wall, which also appears as a topological defect in field theories with broken discrete symmetry.〔A. Vilenkin, Phys. Rep. 121(1985) 263.〕 If infinite, the domain walls cause contradiction with cosmology. But the surface of an NTS is a closed finite wall so, if it exists in the Universe, it does not cause those contradictions. Another point is that if the topological domain wall is closed, it shrinks because of wall tension. As for the NTS surface,it does not shrink since the decreasing of the NTS volume would increase its energy. ==Introduction== Quantum field theory has been developed to describe the elementary particles. However in the mid seventies it was found out that this theory predicts one more class of stable compact objects: non-topological solitons. The NTS represents an unusual coherent state of matter, called also bulk matter. Models were suggested for the NTS to exist in forms of stars, quasars, the dark matter and nuclear matter. An NTS configuration is the lowest energy solution of classical equations of motion possessing a spherical symmetry. Such a solution has been found for a rich variety of field Lagrangians. One can associate the conserved charge with global, local, Abelian and non-Abelian symmetry. It appears to be possible the NTS configuration with bosons as well as with fermions to exist. In different models either one and the same field carries the charge and binds the NTS, or there are two different fields: charge carrier and binding field. The spatial size of the NTS configuration may be elementary small or astronomically large: depending on a model, i.e. the model fields and constants. The NTS size could increase with its energy until the gravitation complicates its behavior and finally causes the collapse. Although in some models the NTS charge is bounded by the stability (or metastability) condition. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Non-topological soliton」の詳細全文を読む スポンサード リンク
|