35,564 research outputs found

    Exact Parametrization of Majorana Neutrino Mass Matrix with Large Mixing

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    Under the assumption that the neutrinos are Majorana particles we study how the lepton mass matrices can be transformed into the simple form which has the same physical quantities by removing redundant parameters. We propose the exact parametrization of the lepton mass matrices which reflects the small nu_e-nu_mu mixing and the large nu_mu-nu_tau mixing. The relations between the twelve parameters and the physical quantities are shown. Furthermore we calculate the MNS matrix by applying the assumptions used in the quark sector. Finally we also check the validity of these assumptions from the experimental values.Comment: 11 pages, LaTeX, no figure

    The NJL-jet model for quark fragmentation functions

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    A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective quark theory. Concentrating on the pion fragmentation function, we first explain why the elementary (lowest order) fragmentation process q --> q \pi is completely inadequate to describe the empirical data, although the "crossed" process \pi --> q \bar{q} describes the quark distribution functions in the pion reasonably well. Taking into account cascade-like processes in a generalized jet-model approach, we then show that the momentum and isospin sum rules can be satisfied naturally, without the introduction of ad hoc parameters. We present results for the Nambu--Jona-Lasinio (NJL) model in the invariant mass regularization scheme and compare them with the empirical parametrizations. We argue that the NJL-jet model, developed herein, provides a useful framework with which to calculate the fragmentation functions in an effective chiral quark theory.Comment: 21 pages, 7 figure

    Quality-equivalent and cost adjusted measurement of international competitiveness in Japanese rice markets:

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    In this research, the quality of foreign japonica rices was evaluated in terms of prices relative to Japanese domestic retail prices. Then, retail prices, consumer benefit, and competitiveness among the foreign rices in the Japanese market were estimated assuming those rices were imported at prices based on their production and transportation costs. According to the results, rices produced in China are quite superior to rices grown in the United States. Further, a 700 percent of tariff, which was discussed in the GATT negotiation and assumed to be imposed on rices imported to Japan, appears to be too low for Chinese rices and too high for American rices.Rice Prices Japan., Tariff on farm produce Japan.,

    Multiple Broken Symmetries in Striped La2−x_{2-x}Bax_{x}CuO4_{4} detected by the Field Symmetric Nernst Effect

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    We report on a thermoelectric investigation of the stripe and superconducting phases of the cuprate La2−x_{2-x}Bax_{x}CuO4_{4} near the x=1/8x=1/8 doping known to host stable stripes. We use the doping and magnetic field dependence of field-symmetric Nernst effect features to delineate the phenomenology of these phases. Our measurements are consistent with prior reports of time-reversal symmetry breaking signatures above the superconducting TcT_{{\rm c}}, and crucially detect a sharp, robust, field-invariant peak at the stripe charge order temperature, TCOT_{{\rm {\scriptscriptstyle CO}}}. Our observations suggest the onset of a nontrivial charge ordered phase at TCOT_{{\rm {\scriptscriptstyle CO}}}, and the subsequent presence of spontaneously generated vortices over a broad temperature range before the emergence of bulk superconductivity in LBCO

    L1521E: A Starless Core in the Early Evolutionary Stage ?

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    We have studied the physical and chemical properties of a quiescent starless core L1521E with various molecular lines. It is found that there exists a compact dense core traced by the H^13CO^+, HN^13C, CCS, and HC_3N lines; their distributions have a single peak at the same position. The core radius is as small as 0.031 pc, whereas the H_2 density at the peak position is as high as (1.3-5.6)times10^5 cm^-3. Although the density is high enough to excite the inversion transitions of NH_3, these lines are found to be very faint in L1521E. The distributions of NH_3 and CCS seem to be different from those of well-studied starless cores, L1498 and L1544, where the distribution of CCS shows a shell-like structure while that of NH_3 is concentrated at the center of the core. Abundances of carbon-chain molecules are higher in L1521E than the other dark cloud cores, and especially those of sulfur-bearing molecules C_nS are comparable to the cyanopolyyne peak of TMC-1. Our results suggest that L1521E would be in a very early stage of physical and chemical evolution.Comment: 10 pages, 3 EPS figures, uses aaspp4.sty and epsf.sty, AAS LaTeX macros v4.0, The Astrophysical Journal, in pres

    Instanton Calculus in R-R 3-form Background and Deformed N=2 Super Yang-Mills Theory

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    We study the ADHM construction of instantons in N=2 supersymmetric Yang-Mills theory deformed in constant Ramond-Ramond (R-R) 3-form field strength background in type IIB superstrings. We compare the deformed instanton effective action with the effective action of fractional D3/D(-1) branes at the orbifold singularity of C^2/Z_2 in the same R-R background. We find discrepancy between them at the second order in deformation parameters, which comes from the coupling of the translational zero modes of the D(-1)-branes to the R-R background. We improve the deformed action by adding a term with space-time dependent gauge coupling. Although the space-time action differs from the action in the omega-background, both actions lead to the same instanton equations of motion at the lowest order in gauge coupling.Comment: 27 pages, version to appear in JHE
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