Sigma modelQ-balls andQ-stars

Abstract

A new kind of Q-balls is found: Q-balls in a non-linear sigma model. Their main properties are presented together with those of their self-gravitating generalization, sigma model Q-stars. A simple special limit of solutions which are bound by gravity alone ("sigma stars") is also discussed briefly. The analysis is based on calculating the mass, global U(1) charge and binding energy for families of solutions parameterized by the central value of the scalar field. Two kinds (differing by the potential term) of the new sigma model Q-balls and Q-stars are analyzed. They are found to share some characteristics while differing in other respects like their properties for weak central scalar fields which depend strongly on the form of the potential term. They are also compared with their "ordinary" counterparts and although similar in some respects, significant differences are found like the existence of an upper bound on the central scalar field. The sigma model Q-stars also contain non-solitonic solutions whose relation with sigma star solutions is discussed.

The energy-momentum tensor and D-term of Q-clouds

“…Now we define M (λ) by evaluating (35) for dilatational variations of the solutions φ(r) → φ(λr) with λ > 0, and substituting r → λ r in the integrals in (36).…”

“…Q-balls are non-topological solitons in theories with global symmetries [23,24,25]. They may have been created under the conditions of the early universe, were discussed as dark matter candidates, and have applications in astrophysics, cosmology, and particle physics [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46].…”

Gravitating solitons and black holes with synchronised hair in the four dimensional O(3) sigma-model

“…We remark that the most general O(3) scalar field ansatz compatible with the isometries of (2.12) contains an extra function for the (φ 1 , φ 2 )-sector 3. Similar solutions of the O(4) sigma model were considered in[56].…”

Energy momentum tensor, and theD-term ofQ-balls

“…5e-h show the different length scales of Q-balls: square roots of the mean square radii of the charge and energy densities and shear forces, Eqs. (34,36), and R 0 which is where p(r) changes sign. The behavior is qualitatively similar: all radii increase as ω → ω min/max , and have global minima around ω ≈ ω abs (for the minimum of r 2 s 1/2 we cannot exclude that it is, within numerical accuracy, exactly at ω abs ).…”

“…Q-balls are nontopological solitons in theories with global Abelian [25] or non-Abelian [26] symmetries, and have been discussed in a variety of approaches with a wide range of applications in particle physics, cosmology, and astrophysics [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45].…”