Figure 1 Branch cuts of the FH m-spoke model. m =4. Solid lines, spokes (u =0, 6=2ka/m); dashed lines, ghost spokes [u =2u9, 6=(2k +1)7/m]. du /d¢ is discontinuous across any branch cut. it fulfills undesired boundary conditions on m addi- tional “ghost” spokes {(7,¢)|r Ry, 6=(2k +1)r/m; k =0,1,...,m—1}, on which u(r,6)=2uy. Subtract- ing ug to normalize the potential to zero at infinity, we realize that the 2m spokes carry positive and negative charges by turns. Figure 1 displays the eight spokes of the case m =4.