Doubly nonlinear Schrödinger ground states on metric graphs

We investigate the existence of ground states at prescribed mass on general metric graphs with half-lines for focussing doubly nonlinear Schrödinger equations involving both a standard power nonlinearity and delta nonlinearities located at the vertices. The problem is proved to be sensitive both to the topology and to the metric of the graph and to exhibit a phenomenology richer than in the case of the sole standard nonlinearity considered by Adami et al (2015 Calc. Var. 54 743-61; 2016 J. Funct. Anal. 271 201-23). On the one hand, we identify various topological features responsible for existence/non-existence of doubly nonlinear ground states in specific mass regimes. On the other hand, we describe the role of the metric in determining the interplay between these different topological properties.