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| \Phi| ^ { 2 } } { \eta ^ { 2 } } } F _ { \mu \nu } F ^ { \mu \nu } with q > 0 where \eta is 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 \beta \equiv ( \frac { m _ { \Phi } } { m _ { A } } ) ^ { 2 } ( m _ { \Phi } and m _ { A } are the masses of the scalar and gauge fields respectively ) .
We show that the stability region of \beta is 0 < \beta < \beta _ { max } ( q ) where \beta _ { max } ( q = 0 ) = 1 ( as expected ) and \beta _ { 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 ) .