Xing, ZZ (reprint author), Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.
The evidence for neutrino oscillations implies that three neutrino flavors (nu(e), nu(mu), nu(tau)) must have different mass states (nu(1), nu(2), nu(3)). The most popular idea of generating tiny masses of nu(i) is to introduce three heavy Majorana neutrinos N-i (for i = 1, 2, 3) into the Standard Model and implement the seesaw mechanism. In this approach the neutrino mixing matrix V appearing in the charged current interactions of nu(i) is not unitary, and the strength of unitarity violation of V is associated with the matrix R which describes the strength of charged current interactions of N-i. We present an explicit parametrization of the correlation between V and R in terms of nine rotation angles and nine phase angles, which can be measured or constrained in the precision neutrino oscillation experiments and by exploring possible signatures of N-i at the LHC and ILC. Two special but viable scenarios, the type-I seesaw model with two heavy Majorana neutrinos and the type-II seesaw model with one heavy Majorana neutrino and one Higgs triplet, are taken into account to illustrate the simplified V-R correlation. The implications of R not equal 0 on the low-energy neutrino phenomenology are also discussed. In particular, we demonstrate that the non-unitarity of V is possible to give rise to an appreciable CP-violating asymmetry between nu(mu) -> nu(tau) and (nu) over bar (mu) -> (nu) over bar (tau) oscillations with short or medium baselines. (c) 2008 Elsevier B.V. All rights reserved.