Can Non-unitary Effect be Prominent in Neutrino Oscillation Measurements?

Subject to the neutrino experiments, the mixing matrix of ordinary neutrinos can still have small violation from unitarity. We introduce a quasi-unitary matrix to interpret this violation and propose a natural scheme to parameterize it. A quasi-unitary factor $Δ_{\rm QF}$ is defined to be measured in neutrino oscillation experiments and our numerical results show that improvement of experimental precision may help us figure out the secret of neutrino mixing.