Figure 2

Sketch for the curves \(C^{\pm }_{\mathrm{HB}}\) in (2). If \(\beta _{\epsilon 0R} > 0\), a stable limit cycle emerges from \(C^{+}_{\mathrm{HB}}\), whereas a saddle limit cycle emerges from \(C^{-}_{\mathrm{HB}}\). The case \(\beta _{\epsilon 0R} < 0\) is analogous just reversing ± by ∓. For the special case \(\beta _{\epsilon 0R} = 0\), two stable limit cycles emerge at the coincident curves \(C^{+}_{\mathrm{HB}}\) and \(C^{-}_{\mathrm{HB}}\). For these plots, we assume \(\beta _{\epsilon 0R} > \alpha _{\epsilon 0R} > 0\)