1mb{1\over m_b} and 1mt{1\over m_t} Expansion of the Weak Mixing Matrix

We perform a $1/m_b$ and $1/m_t$ expansion of the Cabibbo-Kobayashi- Maskawa mixing matrix. Data suggest that the dominant parts of the Yukawa couplings are factorizable into sets of numbers $\vert r>$, $\vert s>$, and $\vert s'>$, associated, respectively, with the left-handed doublets, the right-handed up singlets, and the right- handed down singlets. The first order expansion is consistent with Wolfenstein parameterization, which is an expansion in $sin \theta _c$ to third order. The mixing matrix elements in the present approach are partitioned into factors determined by the relative orientations of $\vert r>$, $\vert s>$, and $\vert s'>$ and the dynamics provided by the subdominant mass matrices. A short discussion is given of some experimental support and a generalized Fritzsch model is used to contrast our approach.Comment: A set of references has been added to ealier related wor

Neutrino masses from discrete gauge symmetries

We investigate a model with an extra $Z_{2}$ gauge symmetry in the Standard Model. We assume that only the scalars and the leptons carry non-zero charge. The symmetry gives a structure to the mass matrix for the neutrinos. With two extra Higgs singlets and two extra singlet right-handed neutrinos we can build a model that fits the requirements of the MSW-solution of the Solar neutrino problem. With a third singlet right-handed neutrino it is also possible to have a 10 eV neutrino, a dark matter candidate.Comment: SNUTP 92-105, Late

Universal Texture of Quark and Lepton Mass Matrices and a Discrete Symmetry Z_3

Recent neutrino data have been favourable to a nearly bimaximal mixing, which suggests a simple form of the neutrino mass matrix. Stimulated by this matrix form, a possibility that all the mass matrices of quarks and leptons have the same form as in the neutrinos is investigated. The mass matrix form is constrained by a discrete symmetry Z_3 and a permutation symmetry S_2. The model, of course, leads to a nearly bimaximal mixing for the lepton sectors, while, for the quark sectors, it can lead to reasonable values of the CKM mixing matrix and masses.Comment: 24 pages, RevTEX, no figure, some references and comments were adde

Quark-lepton mass unification at TeV scales

A scenario combining a model of early (TeV) unification of quarks and leptons with the physics of large extra dimensions provides a natural mechanism linking quark and lepton masses at TeV scale. This has been dubbed as early quark-lepton mass unification by one of us (PQH) in one of the two models of early quark-lepton unification, which are consistent with data, namely SU(4)_PS \otimes SU(2)_L \otimes SU(2)_R \otimes SU(2)_H. In particular, it focused on the issue of naturally light Dirac neutrino. The present paper will focus on similar issues in the other model, namely SU(4)_PS \otimes SU(3)_L \otimes SU(3)_H.Comment: Accepted for publication in PRD: The new version is in agreement with the accepted manuscrip

A possible origin of superconducting currents in cosmic strings

The scattering and capture of right-handed neutrinos by an Abelian cosmic string in the SO(10) grand unification model are considered. The scattering cross-section of neutrinos per unit length due to the interaction with the gauge and Higgs fields of the string is much larger in its scaling regime than in the friction one because of the larger infrared cutoff of the former.The probability of capture in a zero mode of the string accompanied by the emission of a gauge or Higgs boson shows a resonant peak for neutrino momentum of the order of its mass. Considering the decrease of number of strings per unit comoving volume in the scaling epoch the cosmological consequences of the superconducting strings formed in this regime will be much smaller than those which could be produced already in the friction one.Comment: 14 pages Latex, 4 figues/ep

Heavy top quark from Fritzsch mass matrices

It is shown, contrary to common belief, that the Fritzsch ansatz for the quark mass matrices admits a heavy top quark. With the ansatz prescribed at the supersymmetric grand unified (GUT) scale, one finds that the top quark may be as heavy as 145 GeV, provided that tan$\beta$ (the ratio of the vacuum expectation values of the two higgs doublets) $\gg 1$. Within a non-supersymmetric GUT framework with two (one) light higgs doublets, the corresponding approximate upper bound on the top mass is $120~ (90)$ GeV. Our results are based on a general one--loop renormalization group analysis of the quark masses and mixing angles and are readily applied to alternative mass matrix ans\"{a}tze.Comment: LaTeX, 14 figures (not included, available on request

Massive neutrinos, Lorentz invariance dominated standard model and the phenomenological approach to neutrino oscillations

For the electroweak interactions, the massive neutrino perturbative kinematical procedure is developed in the massive neutrino Fock space. This yields the dominant Lorentz invariant Standard Model mass-less flavor neutrino cross-sections as well as the neutrino oscillation cross-sections some of which are Lorentz invariance and flavor conservation violating. But all these oscillating cross-sections being proportional to the squares of neutrino masses are practically unobservable in the laboratory; however, they are consistent with the original Pontecorvo neutrino oscillating transition probability expression at short time (baseline), as presented by Dvornikov. Then, by mimicking the time dependence of the original Pontecorvo neutrino oscillating transition probability, one can formulate the dimensionless neutrino intensity-probability I, by phenomenological extrapolating the time t, or, equivalently the baseline distance L away from the collision point for the oscillating differential cross-section. For the incoming neutrino of 10MeV in energy and neutrino masses from Fritzsch analysis with the neutrino mixing matrix of Harrison, Perkins and Scott, the baseline distances at the first two maxima of the neutrino intensity are L=281km and L=9279km . The intensity I at the first maximum conserves the flavor, while at the second maximum; the intensities violate the flavor, respectively, in the final and initial state. At the end some details are given as to how these neutrino oscillations away from the collision point one should be able to verify experimentally.Comment: 20 preprint, 9 published, page

Non-Universal Correction To Z→bbˉZ \to b {\bar{b}} And Flavor Changing Neutral Current Couplings

A non-universal interaction associated with top quark induces flavor changing neutral currents (FCNC) among light fermions. The size of the FCNC effect depends crucially on the dynamics of the fermion mass generation. In this paper, we study the effect of a non-universal interaction on $Z b b$, $Z b s$ {\it etc}, by using an effective lagrangian technique and assuming the quark mass matrices in the form of a generalized Fritzsch ansatz. We point out that if fitting $R_b$ to the LEP data within $1 \sigma$, the induced FCNC couplings are very close to the experimental limits.Comment: 9 pages, Te

A Phenomenological Study on Lepton Mass Matrix Textures

The three active light neutrinos are used to explain the neutrino oscillations. The inherently bi-large mixing neutrino mass matrix and the Fritzsch type, bi-small mixing charged lepton mass matrix are assumed. By requiring the maximal \nu_\mu-\nu_\tau mixing for the atmospheric neutrino problem and the mass-squared difference approperiate for the almost maximal mixing solution to the solar neutrino problem, the following quantities are predicted: the \nu_e-\nu_\mu mixing, V_{e3}, CP violation in neutrino oscillations, and the effective electron-neutrino mass relevant to neutrinoless double beta decays.Comment: 6 pages, revtex, no figures, confusing points corrected, clarification and refernces adde

Nonzero θ13\theta_{13} and Neutrino Masses from Modified Neutrino Mixing Matrix

The nonzero and relatively large $\theta_{13}$ have been reported by Daya Bay, T2K, MINOS, and Double Chooz Collaborations. In order to accommodate the nonzero $\theta_{13}$, we modified the tribimaximal (TB), bimaxima (BM), and democratic (DC) neutrino mixing matrices. From three modified neutrino mixing matrices, two of them (the modified BM and DC mixing matrices) can give nonzero $\theta_{13}$ which is compatible with the result of the Daya Bay and T2K experiments. The modified TB neutrino mixing matrix predicts the value of $\theta_{13}$ greater than the upper bound value of the latest experimental results. By using the modified neutrino mixing matrices and impose an additional assumption that neutrino mass matrices have two zeros texture, we then obtain the neutrino mass in normal hierarchy when $(M_{\nu})_{22}=(M_{\nu})_{33}=0$ for the neutrino mass matrix from the modified TB neutrino mixing matrix and $(M_{\nu})_{11}=(M_{\nu})_{13}=0$ for the neutrino mass matrix from the modified DC neutrino mixing matrix. For these two patterns of neutrino mass matrices, either the atmospheric mass squared difference or the solar mass squared difference can be obtained, but not both of them simultaneously. From four patterns of two zeros texture to be considered on the obtained neutrino mass matrix from the modified BM neutrino mixing matrix, none of them can predict correctly neutrino mass spectrum (normal or inverted hierarchy).Comment: 13 pages, no figure, some references added, and slight revision due to reviewer(s) comments, to be published in IJMP