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^\frac{q | Φ|^2}{η^2} F_{μν}F^{μν} with q>0 where ηis the scale of symmetry breaking that gives rise to the vortex. For q=0 we obtain the usual embedded (semilocal) Nielsen-Olesen vortex. We find the stability region of the parameter β= (\frac{m_Φ}{m_A})^2 (m_Φand m_A are the masses of the scalar and gauge fields respectively). We show that the stability region of βis 0<β<β_{max}(q) where β_{max}(q=0)=1 (as expected) and β_{max}(q) 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).

4 pages, 4 Figures. The numerical analysis files are available by e-mail upon request