We investigate whether flavor changing neutrino interactions (FCNIs) can be sufficiently large to provide a viable solution to the atmospheric neutrino problem. Effective operators induced by heavy boson exchange that allow for flavor changing neutrino sca

isosingletscalarresonances,weexpectthatthenormalizationwillbesimilartothatoftheπ,ρandηdiscussedbefore.Finallywenotethatthedecayτ

constraintheI=0vectorpart,butatpresentnoupperboundon→itsµ ωwouldbeidealtorateisavailable.Whileonecanalways ne-tunesomeparametersinordertoavoidourbounds,ourbasicassumptionisthatthisisnotthecase.Thusfrom(2.10),(2.15)and(2.16)weconcludethatthee ectivecouplingGfµτcouldbeatmostattheone-percentlevel.

Westillhavetodiscussthecaseoftheintermediatescalarsingletthatcouplesto(LL)sinducingthee ectiveinteractionsin(2.8).SinceOeνisnotgeneratedtogetherwithOe butonlywithoperatorsthatinvolvetwochargedleptonsandtwoneutrinos,thedecayτ →µ e+e isofnousetoconstrainthee ectivecouplings.However,sincethee ectiveoperatorsin(2.8)containonlyleft-handedfermionsratherstrongboundscanbederivedonthe avordiagonaltermsusingleptonuniversality.ThereasonisthatthecorrespondinginteractionsareidenticaltotheSMonesandhavetobeaddedcoherently.

Settingα=β=µ,τthelasttermin(2.8)inducesadditionalcontributionsto αe→Lνα

4√

1νe)Geνe

τντ

ν Gνµν

e)≈1+µ

G<3.8×10 3.(2.20)

F

HereweusedthatOeνhasthesamee ectivecouplingastherelatedoperatorthatinducesthenewcontributionto α→eLνα