Self-force on an electric dipole in the spacetime of a cosmic string

• Review of regularized Green’s function applied to the problem.
• Self-force on an electric dipole in the string spacetime for some orientations.
• Representation via graphs of the self-forces versus angular parameter of the cosmic string.
• Self-force induced by the string seen as an interaction between two dipoles.
• Discussion about the superposition principle in this non-trivial background.

We calculate the electrostatic self-force on an electric dipole in the spacetime generated by a static, thin, infinite and straight cosmic string. The electric dipole is held fixed in different configurations, namely, parallel, perpendicular to the cosmic string and oriented along the azimuthal direction around this topological defect, which is stretched along the zz axis. We show that the self-force is equivalent to an interaction of the electric dipole with an effective dipole moment which depends on the linear mass density of the cosmic string and on the configuration. The plots of the self-forces as functions of the parameter which determines the angular deficit of the cosmic string are shown for those different configurations.