New physics signals at long baseline experiments

We develop a formalism that gives analytically tractable expressions for flavor conversion probabilities at long baseline experiments, in the presence of any number of sterile neutrino species or with CPT violation. Using a perturbative expansion in the small parameters we show that, even in a completely general analysis, only certain specific combinations of the mixing parameters are relevant and hence can be probed in the experiments. We identify the long baseline experiments which will be able to probe those observable combinations in a clean manner and estimate their reach in measuring or constraining those observables.