Neutrino Mass Matrix Predicted From Symmetric Texture

Within the framework of grand unified theories, we make full analysis of symmetric texture to see if such texture can reproduce large neutrino mixings, which have recently been confirmed by the observed solar and atmospheric neutrino oscillation experiments. It is found that so-called symmetric texture with anomalous U(1) family symmetry with Froggatt-Nielsen mechanism does not provide a natural explanation of two large mixing angles. On the contrary we should adopt "zero texture" which have been extensively studied by many authors and only this scenario can reproduce two large mixing angles naturally. Under such "zero texture" with minimal symmetric Majorana matrix, all the neutrino masses and mixing angles, 6 quantities, are expressed in terms of up-quark masses, $m_t,m_c,m_u$ with two adjustable parameters. This provides interesting relations among neutrio mixing angles, $\tan^2 2\theta_{12} \simeq \frac{144m_c}{m_t} \tan^2 2\theta_{23} \cos^2 \theta_{23}, \quad \sin^2 \theta_{13} \simeq \frac{4m_c}{m_t}\sin^2 \theta_{23} \cos^2 \theta_{12}$. Thus $|U_{e3}|$ is predicted to lie within the range $0.01-0.06$. Also absolute masses of three neutrinos are predicted almost uniquely. This is quite in contrast to the case where bi-large mixings come from the charged lepton sector with non-symmetric mass matrix, which does not provide the information of neutrino masses.Comment: 23 pages, latex, 15 figures. Preprint version contains "low resolution" figures to reduce the size of overall postscript file. Please contact authors to obtain the high resolution versio

Neutrino Bi-Large Mixings and Family

After a brief review of quark-lepton relations in grand unified theories (GUT), we show that the Pati-Salam relation with only one type of Higgs field configuration with "four zero symmetric texture" can reproduce two large neutrino mixings as well as observed mass differences. This is quite in contrast to the case of SU(5) where bi-large mixings essentially come from the charged lepton sector with non-symmetric charged lepton mass matrix.Comment: 6 pages, latex, uses ws-procs9x6.cls. Talk presented by Bando at 4th Workshop on Neutrino Oscillations and their Origin (NOON2003), Kanazawa, Japan, 10-14 Feb 2003. To appear in the proceeding

Geometric Quantum Gates, Composite Pulses, and Trotter-Suzuki Formulas

We show that all geometric quantum gates (GQG's in short), which are quantum gates only with geometric phases, are robust against control field strength errors. As examples of this observation, we show (1) how robust composite rf-pulses in NMR are geometrically constructed and (2) a composite rf-pulse based on Trotter-Suzuki Formulas is a GQG.Comment: 4 pages, no figure

Sterile Neutrinos in a Grand Unified Model

The recent experimental results indicating the neutrino oscillations may strongly suggest that at least one more light neutrino species is required in order to reconcile the existing data. In the simple GUT frameworks, this fact seems difficult to preserve the parallelism between quarks and leptons. In this letter, we investigate an SO(10) grand unified model with a pair of extra generations in addition to the known three ones. Using the GUT relations, the obtained neutrino mass matrix naturally indicates that one of the SU(2) singlet (sterile) neutrino is very light and has large mixing with muon neutrino, which can explain the atmospheric neutrino anomaly, and the hot dark matter neutrino is also provided. The solar neutrino problem can be solved by the mixing with muon neutrino consistently with quark mixing, namely, the Cabibbo angle.Comment: 15 pages, 5 eps figure

A Signal for Technicolor?

We propose an interpretation for the ($l\bar l\gamma \gamma ,\ M_{\gamma \gamma }=60{\rm GeV}$) events, which have recently been reported by L3 group at LEP. This may be a first signal of `Technicolor' theory.Comment: 5pages, two Figures not included, phyzzx.te

E_6 Unification with Bi-Large Neutrino Mixing

A scenario of SO(10) grand unified theory (GUT) proposed by one of the authors is extended to E_6 unification. This gives realistic quark and lepton mass matrices. In neutrino sector, the model reproduces large mixing angle (LMA) MSW solution as well as large mixing angle for atmospheric neutrino anomaly. In this model, right-handed down quark and left-handed lepton of the first and second generation belong to a single multiplet 27. This causes natural suppression of flavor changing neutral current(FCNC).Comment: 23 pages, V2:published versio

Neutrino Mass Matrix in Terms of Up-Quark Masses

We demonstrate that under the "symmetric zero texture" with minimal Majorana mass matrix, neutrino masses and mixing angles are expressed in terms of up-quark masses, $m_t,m_c,m_u$. This provides interesting relations among neutrino mixing angles and up-type quark masses. Especially we predict $|U_{e3}| \leq 0.11$ even if we include the small mixing effects coming from charged lepton side. Also absolute masses of three neutrinos are predicted almost uniquely. This is quite in contrast to the case where bi-large mixings come from the charged lepton sector with non-symmetric charged lepton mass matrix.Comment: 9 pages, latex, 2 figures. Talk presented by Bando at the 2002 International Workshop On "Strong Coupling Gauge Theories and Effective Field Theories" (SCGT 02), Nagoya, Japan, 10-13 December 200

Higgs Doublets as Pseudo Nambu-Goldstone Bosons in Supersymmetric E_6 Unification

The idea to have Higgs doublets as pseudo Nambu-Goldstone (PsNG) multiplet is examined in the framework of supersymmetric E_6 unified theory. We show that extra PsNG multiplets other than the expected Higgs doublets necessarily appear in the E_6 case. If we demand that the extra PsNG multiplets neither disturb the gauge coupling unification nor make the color gauge coupling diverge before unification occurs, only possibility for the extra PsNG is 10+\bar{10} of SU(5). This is realized when the symmetry breaking E_6 \to SO(10) occurs in the \phi(27)+\phi(\bar{27}) sector while E_6 \to SU(4)_C\times SU(2)_L\times U(1)\times U(1) in the \Sigma(78) sector. The existence of 10+\bar{10} multiplets with mass around 1 TeV is therefore a prediction of this E_6 PsNG scenario. Implication of their existence on the proton decay is also discussed.Comment: 16 pages, no figures, LaTeX(PTPTeX style

Construction of Supergravity Backgrounds with a Dilaton Field

A new class of non-compact Kahler backgrounds accompanied by a non-constant dilaton field is constructed as a supergravity solution. It is interpreted as a complex line bundle over a base manifold comprising of a combination of arbitrary coset spaces, and also includes the case of Calabi-Yau manifolds. The resulting backgrounds have U(1) isometry. We consider N=2 supersymmetric sigma-models on them, and derive a non-Kahlerian solution by U(1) duality transformation, which preserves N=2 supersymmetry.Comment: 13 pages, minor correction

Hidden Local Symmetry at One Loop

We show that one-loop corrections with the hidden gauge boson loop preserve in the low energy limit all the successful tree level predictions of the hidden local symmetry in the SU(2)${}_L$$\times$SU(2)${}_R$$/$SU(2)${}_V$ chiral Lagrangian. Most amazingly, the $\rho$ meson dominance of the pion electromagnetic form factor survives the one-loop corrections at any momentum, if and only if we take the parameter choice $a=2$. For the choice $a=1$ (``vector limit"), $a$ is not renormalized ($Z_a=1$) and no deviation from $a=1$ is induced by the loop effects of the hidden gauge bosons. Actually, $a=1$ is a nontrivial ultraviolet fixed point.Comment: 15 pages (LaTeX), 7 figures (not included, available upon e-mail request, written using epic and eepic style file), DPNU-92-4