Narrow Results

We present a detailed analysis and phenomenological consequences of neutrino mass matrix, $M_{\nu }$, with one-zero texture in the flavor basis where the active neutrino sector is extended by one sterile neutrino (3+1 case). In particular, our aim is to explore behavior of the sterile mixing parameters in detail when one of the elements of the neutrino mass matrix goes to zero. To study this, we consider two distinct mass spectrum of the active neutrinos: (i) completely hierarchical mass spectrum with a vanishing neutrino mass and (ii) completely quasidegenerate mass spectrum. In 3+1 scenario, the low energy neutrino mass matrix, $M_{\nu }$, is a $4\times 4$ matrix and has 10 independent elements. Thus it can have 10 possible one-zero textures. From the earlier studies it can be inferred that, if one assumes one vanishing neutrino mass, then only seven of these $M_{\nu }$ are phenomenologically allowed by the current neutrino oscillation data. On the other hand, if the neutrinos are quasidegenerate then there are eight phenomenologically viable one-zero textures. In this paper, we study the correlations between the sterile mixing parameters for each of these allowed textures for both mass spectrum and also their implications on the effective Majorana mass.

In the light of several recent analyses pointing toward texture 4-zero Fritzsch-like quark mass matrices as the only viable structures for quark mass matrices, this work adopts a model independent approach to reconstruct an alternate and simplified structure of texture specific quark mass matrices in a generalized “$u$-diagonal” basis within the Standard Model framework using the unitarity of CKM matrix and the observed hierarchies in quark mass spectra and mixing angles. It is observed that the measured $1\sigma$ values of the three physical parameters namely $m_u$, $m_d$ and $s_{12}$ naturally lead to the vanishing of (11) element in the down type quark mass matrix and that the single measurable CP violating phase ${\delta }_{13}$ in the CKM matrix is sufficient enough in $M_d^{\prime }$ to explain the observed mixing pattern in a suitable basis. The leading order as well as exact analytic phenomenological solutions are addressed for the modest pattern of quark mass matrices derived from CKM matrix and precision measurements of mixing parameters.

The Standard model of particle physics is a very successful theory of strong weak and electromagnetic interactions. This theory is perturbative at sufficiently high energies and renormalizable, it describes these interactions at quantum level. However it has a number of limitations, one being the fact that it has 28 free parameters assuming massive neutrinos. Within the Standard model these parameters can not be explained, however they can be accommodated in the standard theory. Particularly the masses of the fermions are not predicted by the theory. The existence of the neutrino masses can be regarded as the first glimpse of the physics beyond the standard model. we have described the quark and lepton masses and mixings in context of four zero texture (FZT). In the four zero texture case the fermion masses and mixing can be related. We have made some predictions using tribimaximal mixing, the near tribimaximal (TBM) mixing. Our results show that under the TBM the neutrinos have normal, but weak hierarchy. Under near tribimaximal mixing, we find that the neutrino masses in general increase, if the value of solar angle increases from its TBM value and vice versa. It appears that the neutrinos become more and more degenerate for solar angle values higher than TBM value and hierarchical for lower values of solar angle.