New matter effects in terrestrial neutrino oscillation experiments

Consequences of a new force mediated by a light scalar particle for neutrino oscillation experiments are considered. Such a force could give rise to neutrino masses and mixings whose matter dependence for earth densities is much more significant than the MSW effect. We consider the effects of such a new force on the limits derived from oscillation experiments, and examine how the constraints on neutrino models are altered. Re-analysis of neutrino data, as well as new experiments in which large matter effects are systematically explored, is required to directly probe such physics beyond the standard model.