“…An analytical proof based on the bifurcation theory and complex analysis tools was devised by Burbea in [18] who proved the existence of m-fold (for any m ∈ N * ) symmetric V-states bifurcating from Rankine vortices with angular velocity Ω m := m−1 2m . More investigations on the V-states in different settings like the doubly-connected patches, vortex pairs, boundary effects or for different models has been implemented during the past decade by several authors, for more details we refer to [19,20,27,28,29,30,31,32,33,34,36,37,38,39,40]. Concerning (QGSW) λ there are a few results dealing with relative equilibria.…”