Nuclear μ−–e− conversion in strange quark sea

We study nuclear μ−–e− conversion in the general framework of effective Lagrangian approach without referring to any specific realization of the physics beyond the standard model (SM) responsible for lepton flavor violation (L/f). All the possible types of short range interactions (non-photonic mechanisms), i.e., (pseudo-)scalar, (axial-)vector and tensor, are included in our formalism. We show that the μ−–e− conversion in the strange nucleon sea via the scalar interactions is comparable with that in the valence quarks. This provides an insight into the strange quark couplings beyond the SM. From the available experimental data on μ−–e− conversion and expected sensitivities of planned experiments we derived upper bounds on the generic L/f-parameters of μ−–e− conversion sensitive to the relevant u-, d- and s-quark couplings.