Extended Data Fig. 3: Obstructions to nodes annihilation through the braiding of nodes on the (Brillouin zone) torus.
From: Experimental observation of non-Abelian topological acoustic semimetals and their phase transitions
In a the moving node does not cross the whole Brillouin zone, in b (AB) and b (CD) the moving node crosses the Brillouin zone along one of the cyclic direction of the torus leaving a non-contractible DS behind. The patch Euler class (\(\xi ({{{\mathcal{D}}}})\)) and the topological configuration after braiding are fully determined by the nodes charges and the Dirac strings of the initial configuration.
