Stabilizing the semilocal string with a dilatonic coupling

Abstract

We demonstrate that the stability of the semilocal vortex can be significantly improved by the presence of a dilatonic coupling of the form e qjÈj 2 2 F F with q > 0 where is the scale of symmetry breaking that gives rise to the vortex. For q ¼ 0 we obtain the usual embedded (semilocal) Nielsen-Olesen vortex. We find the stability region of the parameter ð m È m A Þ 2 (m È and m A are the masses of the scalar and gauge fields, respectively). We show that the stability region of is 0 < < max ðqÞ where max ðq ¼ 0Þ ¼ 1 (as expected) and max ðqÞ is an increasing function of q. This result may have significant implications for the stability of the electroweak vortex in the presence of a dilatonic coupling (dilatonic electroweak vortex).

Dilatonic topological defects in3+1dimensions and their embeddings

“…This is an extension of a recent study by two of the authors that focused only on the case of the dilatonic semilocal (embedded) vortex [38]. The structure of this paper is the following: In the next section we briefly review the Nielsen-Olesen U(1) gauged vortex and demonstrate the existence of its dilatonic generalization.…”

“…The later possibility is amplified by the observational fact that a dipole fit of the dark energy distribution using Type Ia supernovae leads to a dipole whose direction is only about 10 • away from the α dipole direction [29]. Therefore, topological defects emerging due to topologically non-trivial configurations of the field ψ (dilatonic defects) have the potential to play an interesting role in cosmology [30,[35][36][37][38][39]. It is therefore interesting to investigate their field configuration properties which emerge as generalizations of the corresponding ordinary defects where there is no coupling between the scalar field and the gauge field kinetic term.…”

“…• The stability of the gauged embedded defects [40][41][42][43][44][45] is significantly affected by the dilatonic coupling due to the spatial variation of the effective mass of the scalar field [38].…”

“…The stability analysis of the embedded dilatonic NO vortex was presented in [38]. Here we briefly sketch the analysis for completeness.…”

“…[38] (Fig. 5) since the functional form of the dilatonic coupling is different in our case (we assume a power law while an exponential B(Φ † Φ) = e qΦ † Φ η 2 was assumed in [38]). The stability region β(q) for the embedded dilatonic NO vortex.…”