We have attempted to extend the parameter space of the elements of the texture 4 zero Hermitian quark mass matrices, to include the case of 'weak hierarchy' amongst them along with the usually considered 'strong hierarchy' case. This has been carried out by giving wide variation to the hierarchy defining parameters D U and D D , having implications for the structural features of the mass matrices. We find that not only the weakly hierarchical mass matrices are able to reproduce the strongly hierarchical mixing angles but also both the phases having their origin in the mass matrices have to be non zero to achieve compatibility of these matrices with recent quark mixing data. Further noting the difference between the exclusive and inclusive values of V ub , we have carried out separate analyses corresponding to these.

For Majorana or Dirac neutrinos, using Fritzsch-like texture 4 zero mass matrices with parallel texture structures for the charged leptons and the Dirac neutrino mass matrix (M_{\nu D}), detailed predictions for cases pertaining to normal/inverted hierarchy as well as degenerate scenarios of neutrino masses have been carried out. The inverted hierarchy as well as degenerate scenarios seem to be ruled out at 3 \sigma C.L. for both Majorana and Dirac neutrinos. For normal hierarchy, Jarlskog's rephasing invariant parameter J, the CP violating Dirac-like phase \delta and the effective neutrino mass m_{ee} have been calculated. For this case, lower limits of m_{\nu_1} and \theta_{13} would have implications for the nature of neutrinos.Comment: 15 pages, 3 figures, minor changes in figures and tex

Texture specific quark mass matrices which are hermitian and hierarchical are examined in detail . In the case of texture 6 zeros matrices, out of sixteen possibilities examined by us, none is able to fit the low energy data (LED), for example, |V us |= 0.2196 ± 0.0023, |V cb |= 0.0395 ± 0.0017, | V ub V cb |= 0.08 ± 0.02, |V td | lies in the range 0.004 -0.013 (PDG). Similarly none of the 32 texture 5 zeros mass matrices considered is able to reproduce LED. In particular, the latest data from LEP regarding | V ub V cb | (= 0.093 ± 0.016) rules out all of them. In the texture 4 zeros case, we find that there is a unique texture structure for U and D mass matrices which is able to fit the data. PACS number(s): 12.15. Ff, 14.60.Pq, 96.60.Jw The raison d'être for the existence of three well seperated families of charged fermions remains ununderstood in the context of present day high energy physics. The mystery regarding the fermion masses has further deepened with the observation of "neutrino oscillations" by the Superkamiokande Collaboration [1] implying nonzero masses for the neutrinos and thus, giving for the first time a strong signal for the physics beyond the standard model. In the absence of any deeper understanding of fermion masses, attempts have been made on the one hand to understand arbitrary standard model Yukawa couplings of the fermions from more fundamental theories such as GUTs [2] composite models [3], left right symmetric models [4], etc.. On the other hand, attempts have been made to discover phenomenological quark mass matrices, which are in tune with the low energy data(LED). In this regard, specific ansatz for the quark mass matrices have been tried with a fair degree of success [5] - [13] to explain quark mixing matrix. Similarly phenomenological neutrino mass matrices have been considered [13,14] which attempt to accomodate simultaneously the Solar Neutrino Problem (SNP), Atmospheric Neutrino Problem (ANP) and Neutrino Oscillations observed by LSND.

Considering Dirac neutrinos and Fritzsch-like texture 6 zero and 5 zero mass matrices, detailed predictions for cases pertaining to normal/inverted hierarchy as well as degenerate scenario of neutrino masses have been carried out. All the cases considered here pertaining to inverted hierarchy and degenerate scenario of neutrino masses are ruled out by the existing data. For the normal hierarchy cases, the lower limit of m ν 1 and of s 13 as well as the range of Dirac-like CP violating phase δ l would have implications for the texture specific cases considered here.

Using seesaw mechanism and Fritzsch-like texture 6 zero and 5 zero lepton Dirac mass matrices, detailed predictions for cases pertaining to normal/inverted hierarchy as well as degenerate scenario of neutrino masses have been carried out. All the cases considered here pertaining to inverted hierarchy and degenerate scenario of neutrino masses are ruled out by the existing data. For the normal hierarchy cases, the lower limit of m_{\nu 1} and of s_{13} as well as the range of Dirac-like CP violating phase \delta would have implications for the texture 6 zero and texture 5 zero cases considered here.Comment: 13 pages, 4 figures. Small changes to the previous version and a new reference adde

The magnetic moments of J P = 3 2 + decuplet baryons have been calculated in the chiral constituent quark model (χCQM) with explicit results for the contribution coming from the valence quark polarizations, sea quark polarizations, and their orbital angular momentum. Since the+ decuplet baryons have short lifetimes, the experimental information about them is limited. The χCQM has important implications for chiral symmetry breaking as well as SU (3) symmetry breaking since it works in the region between the QCD confinement scale and the chiral symmetry breaking scale. The predictions in the model not only give a satisfactory fit when compared with the experimental data but also show improvement over the other models. The effect of the confinement on quark masses has also been discussed in detail and the results of χCQM are found to improve further with the inclusion of effective quark masses.

Motivated by the possibility of the low value of sin2β in the measurements of BABAR and BELLE collaborations, we have explored the possibilty of construction of reference unitarity triangle using the unitarity of the CKM matrix, the existence of nonzero CP violating phase δ and the experimental values of the well known CKM elements, without involving any inputs from the processes which might include the new physics effects. The angles of the reference triangle are evaluated by finding δ through the Jarlskog's rephasing invariant parameter J. The present data and the unitarity of the CKM matrix give δ = 50 o ± 20 o , which translates to 130 o ± 20 o in the second quadrant. The corresponding range for sin2β is 0.21 to 0.88. This range is broadly in agreement with the recently updated BABAR and BELLE results. However, a value of sin2β≤0.2, advocated by Silva and Wolfenstein as a benchmark for new physics, would suggest a violation in the three generation unitarity and would hint towards the existence of a fourth generation. Further, the future refinements in the CKM elements will push the lower limit on sin2β still higher.

Unitarity along with precision measurements of sin 2β, V us and V cb allows one to find a lower bound V ub ≥ 0.0035 which, on using the recently measured angle α of the unitarity triangle, translates to V ub = 0.0035 ± 0.0002. This precise value, stable for a good deal of changes in α, along with CP violating phase δ found from unitarity allows the construction of a 'precise' CKM matrix. The above unitarity based value of V ub is in agreement with the latest exclusive value used as input by UTfit, CKMfitter, HFAG, however underlines the so called 'tension' faced by the latest inclusive V ub = 0.00449 ± 0.00033. Further, using this inclusive value of V ub along with the latest sin 2β, one finds δ = 23 o − 39 o , again in conflict with δ measured in B-decays. The calculated ranges of the elements of the CKM matrix are in excellent agreement with those obtained recently by UTfit, CKMfitter and HFAG. Also, the ratio Vts V td is in agreement with its latest measured value, whereas there is some disagreement between the 'measured' and the calculated V td values.