Present and Future Bounds on Non-Standard Neutrino Interactions

Original · EN

We consider Non-Standard neutrino Interactions (NSI), described by four-fermion operators of the form (να γνβ) (f γf), where f is an electron or first generation quark. We assume these operators are generated at dimension ≥ 8, so the related vertices involving charged leptons, obtained by an SU(2) transformation νδ → eδ, do not appear at tree level. These related vertices necessarily arise at one loop, via W exchange. We catalogue current constraints from ² θW measurements in neutrino scattering, from atmospheric neutrino observations, from LEP, and from bounds on the related charged lepton operators. We estimate future bounds from comparing KamLAND and solar neutrino data, and from measuring ² θW at the near detector of a neutrino factory. Operators constructed with νμ and νₑ should not confuse the determination of oscillation parameters at a νfactory, because the processes we consider are more sensitive than oscillations at the far detector. For operators involving ντ, we estimate similar sensitivities at the near and far detector.