Rare interactions of neutrinos with matter as contraction of the standard electroweak model

The modification of the electroweak model, which lepton sector corresponds to the contracted gauge group SU(2; j)U(1) whereas boson and quark sectors are standard ones, is suggested. The field space of the model is fibered under contraction in such a way that neutrino fields are in the fiber and all other fields are in the base. Properties of the fibered field space are understood in context of semi-Riemannian geometry. For small, but different from zero contraction parameter, this model can explain why neutrinos so rarely interact with anything. Small contraction parameter is connected with the universal Fermi constant of weak interactions and is approximated as jmin ≈ 10 −3, when energy is measured in GeV. The modified model should be considered at low energies much less then gauge bosons masses.