Non-perturbative tests of continuum HQET through small-volume two-flavour QCD

We study the heavy quark mass dependence of selected observables constructed from heavy-light meson correlation functions in small-volume two-flavour lattice QCD after taking the continuum limit. The light quark mass is tuned to zero, whereas the range of available heavy quark masses $m_h$ covers a region extending from around the charm to beyond the bottom quark mass scale. This allows entering the asymptotic mass-scaling regime as $1/m_h \to 0$ and performing well-controlled extrapolations to the infinite-mass limit. Our results are then compared to predictions obtained in the static limit of continuum Heavy Quark Effective Theory (HQET), in order to verify non-perturbatively that HQET is an effective theory of QCD. While in general we observe a nice agreement at the few-% level, we find it to be less convincing for the small-volume pseudoscalar decay constant when perturbative matching is involved.Comment: 42 pages, 10 figures, 12 tables; JHEP styl

Maximal Neutrino Mixing and Maximal CP Violation

We propose a phenomenological model of lepton mixing and CP violation based on the flavor democracy of charge leptons and the mass degeneracy of neutrinos. A nearly bi-maximal flavor mixing pattern, which is favored by current data on atmospheric and solar neutrino oscillations, emerges naturally from this model after explicit symmetry breaking. The rephasing-invariant strength of CP or T violation can be as large as one percent, leading to significant probability asymmetries between \nu_\mu \to \nu_e and \bar{\nu}_\mu \to \bar{\nu}_e (or \nu_e \to \nu_\mu) transitions in the long-baseline neutrino experiments.Comment: LaTex 12 pages (2 figures included

Fermion masses and symmetry breaking of a U(2) flavour symmetry

We show how a specific sequential breaking pattern of a U(2) flavour symmetry occurs automatically in a broad framework. The relative orientation in U(2) space of the spurion fields that breaks the U(2) symmetry is uniquely fixed, thus determining the form of the fermion mass matrices in a predictive way.Comment: 9 pages, uses amsmath.st

Non-diagonal charged lepton mass matrix and non-zero θ13\theta_{13}

Assuming that the neutrino mass matrix is diagonalized by the tribimaximal mixing matrix, we explore the textures for the charged lepton mass matrix that render an $U_{PMNS}$ lepton mixing matrix consistent with data. In particular we are interested in finding the textures with the maximum number of zeros. We explore the cases of real matrices with three and four zeros and find that only ten matrices with three zeros provide solutions in agreement with data. We present the successful Yukawa textures including the relative sizes of their non-zero entries as well as some new and interesting relations among the entries of these textures in terms of the charged lepton masses. We also show that these relations can be obtained directly from a parametrization of the charged lepton mixing matrix $U_l$.Comment: 16 pages, two figures. A parametrization of the mixing matrix $U_l$ was introduced to explain observed patterns in textures. References adde

Democratic Neutrino Mixing and Radiative Corrections

The renormalization effect on a specific ansatz of lepton mass matrices, arising naturally from the breaking of flavor democracy for charged leptons and that of mass degeneracy for light neutrinos, is studied from a superhigh energy scale M_0 \sim 10^{13} GeV to the electroweak scale in the framework of the minimal supersymmetric standard model. We find that the democratic neutrino mixing pattern obtained from this ansatz may in general be instable against radiative corrections. With the help of similar flavor symmetries we prescribe a slightly different scheme of lepton mass matrices at the scale M_0, from which the democratic mixing pattern of lepton flavors can be achieved, after radiative corrections, at the experimentally accessible scales.Comment: RevTex 8 pages. Phys. Rev. D (in printing

A Search for the Fourth SM Family Fermions and E_6 Quarks at μ+μ−\mu ^{+}\mu ^{-} Colliders

The potential of $\mu ^{+}\mu ^{-}$ colliders to investigate the fourth SM family fermions predicted by flavour democracy has been analyzed. It is shown that muon colliders are advantageous for both pair production of fourth family fermions and resonance production of fourth family quarkonia. Also isosinglet quarks production at $\mu ^{+}\mu ^{-}$ colliders has been investigated.Comment: 9 pages, 5 table

Hierarchy and Up-Down Parallelism of Quark Mass Matrices

In view of the quark mass hierarchy and in the assumption of the up-down parallelism, we derive two phenomenologically-favored patterns of Hermitian quark mass matrices from the quark flavor mixing matrix. We compare one of them with two existing {\it Ans$\it\ddot{a}$tze} proposed by Rosner and Worah and by Roberts {\it et al}, and find that only the latter is consistent with the present experimental data.Comment: RevTex 9 pages. Accepted for publication in Phys. Rev.

The anomalous magnetic moment of the muon and radiative lepton decays

The leptons are viewed as composite objects, exhibiting anomalous magnetic moments and anomalous flavor-changing transition moments. The decay $\mu \to e \gamma$ is expected to occur with a branching ratio of the same order as the present experimental limit.Comment: 5 page

On suppressing the Higgsino-mediated proton decay in SUSY SO(10) GUT's

Using the freedom in SO(10) GUT's one can generalize the existing models without changing the mass spectrum of fermions to obtain a significant suppression of proton decay resulting from the baryon number violating operators of dimension 5. In some limiting cases, their contributions can be made negligible compared to the dimension 6 operators resulting from the heavy gauge bosons exchange.Comment: 19 pages, 3 Postscript figures, 2 mpost figures, rearranged plots, corrected typo

Spontaneous Symmetry Breaking through Mixing

We discuss a model, in which the negative mass square needed in the Higgs mechanism is generated by mixing with a heavy scalar. We have two scalar doublets in the standard model. Phenomenological properties of the heavy new scalar are discussed. The heavy scalar can be detected by the LHC.Comment: 4 page