Interpreting the LSND anomaly: sterile neutrinos or CPT-violation or…?

We first study how sterile neutrinos can fit the 5σ ν̄μ→ν̄e LSND anomaly: 2+2 solutions are strongly disfavoured by solar and atmospheric data, while 3+1 solutions can still give a poor fit (for a specific range of oscillation parameters, to be tested by MiniBooNE). If MiniBooNE will see no νμ→νe transitions, we will have a hint for CPT violation. Already now, unlike sterile neutrinos, CPT-violating neutrino masses can accommodate all safe and unsafe data. We study how much CPT must be conserved according to atmospheric and K2K data and list which CPT-violating signals could be discovered by forthcoming solar and long-baseline experiments.