Restoration of isotropy on fractals

We report a new type of restoration of macroscopic isotropy (homogenization) in fractals with microscopic anisotropy. The phenomenon is observed in various physical setups, including diffusions, random walks, resistor networks, and Gaussian field theories. The mechanism is unique in that it is absent in spaces with translational invariance, while universal in that it is observed in a wide class of fractals.Comment: 11 pages, REVTEX, 3 postscript figures. (Compressed and encoded figures archived by "figure" command). To appear in Physical Review Letter

Flavor changing neutrino interactions and CP violation in neutrino oscillations

We investigate the interference effects of non-standard neutrino-matter interactions (NSNI) with the mass-induced neutrino oscillations. The NSNI is composed of flavor-changing neutrino interactions (FCNI) and flavor-diagonal neutrino interactions (FDNI). Both of the interactions are introduced in the \nu_\mu -\nu_\tau sector and the \nu_e -\nu_\mu sector in order to study their effects in \nu_\mu\to\nu_\tau and \nu_\mu\to\nu_e oscillations, respectively. The FCNI effect proves to possibly dominate the CP violating effect and significantly survive as a fake CP violating effct in the neutrino energy region where the pure CP violating effect, ordinary matter effect and FDNI effect fall, for example, above 4 GeV at the baseline of L=730 km in the \nu_\mu\to\nu_\tau oscillation for the maximum parameter values of FCNI and FDNI allowed by the atmospheric neutrino oscillation data. The FCNI and FDNI effects on CP violation in the $\nu_\mu\to\nu_e$ oscillation are negligibly small due to the stringent constraints on FCNI from the bounds on lepton flavor violating processes and on FDNI from the limits on lepton universality violation.Comment: 18 pages in LaTeX2e, 12 ps figures. The discussion of detectability of the CP violation is delete

Electron Mass Enhancement due to Anharmonic Local Phonons

In order to understand how electron effective mass is enhanced by anharmonic local oscillation of an atom in a cage composed of other atoms, i.e., {\it rattling}, we analyze anharmonic Holstein model by using a Green's function method. Due to the evaluation of an electron mass enhancement factor $Z$, we find that $Z$ becomes maximum when zero-point energy is comparable with potential height at which the amplitude of oscillation is rapidly enlarged. Cooperation of such quantum and rattling effects is considered to be a key issue to explain the electron mass enhancement in electron-rattling systems.Comment: 3 pages, 3 figures, to appear in J. Phys. Soc. Jpn. Suppl. (Proceedings for International Conference on Heavy Electrons

Relative Performance of UK and Japanese Electricity Distribution Systems 1985-1998: Lessons for Incentive Regulation

International comparisons can be used to study relative efficiency of decision-making units in an industry in a wider context. In particular, cross-country comparisons can, help regulators of natural monopoly firms to assess the relative performance of their regulation regime and national firms with those of other countries. The relative performance of frontier firms is important as these may be subject to lax regulation and could constitute benchmarks for regulation of other firms. The results of empirical studies can be sensitive to the choice of techniques and models. The UK and Japanese electricity distribution utilities have been subject to yardstick regulation since 1990 and 1996 respectively. In this paper we present an analysis of the development and relative performance of electricity distribution utilities in the UK and Japan between 1985 and 1998. The results allow the examination of the impact of privatisation and regulation on the UK firms and their scope for further efficiency gains. The paper presents the findings from applying input distance functions with data envelopment analysis (DEA), stochastic frontier analysis (SFA), and corrected ordinary least square (COLS) techniques using cost based model specifications in a dynamic setting.Technical Efficiency, Efficiency Analysis, Electricity Distribution Systems, Incentive Regulation, International Comparison

Fermion Masses and Mixings in a String Inspired Model

In the context of Calabi-Yau string models we explore the origin of characteristic pattern of quark-lepton masses and the CKM matrix. The discrete $R$-symmetry $Z_K \times Z_2$ is introduced and the $Z_2$ is assigned to the $R$-parity. The gauge symmetry at the string scale, $SU(6) \times SU(2)_R$, is broken into the standard model gauge group at a very large intermediate energy scale. At energies below the intermediate scale down-type quarks and also leptons are mixed with unobserved heavy states, respectively. On the other hand, there are no such mixings for up-type quarks. Due to the large mixings between light states and heavy ones we can derive phenomenologically viable fermion mass hierarchies and the CKM matrix. Mass spectra for intermediate-scale matter beyond the MSSM are also determined. Within this framework proton lifetime is long enough to be consistent with experimental data. As for the string scale unification of gauge couplings, however, consistent solutions are not yet found.Comment: 49 pages, 1 figure, Latex Revised version includes discussion on FCNC problems. Final version to appear in Prog. Theor. Phys. Vol.96 No.

A possible route to spontaneous reduction of the heat conductivity by a temperature gradient driven instability in electron-ion plasmas

We have shown that there exists low-frequency growing modes driven by a global temperature gradient in electron and ion plasmas, by linear perturbation analysis within the frame work of plasma Kinetic theory. The driving force of the instability is the local deviation of the distribution function from the Maxwell-Boltzmann due to global temperature gradient. Application to the intracluster medium shows that scattering of the particles due to waves excited by the instability is possible to reduce mean free paths of electron and ion down to five to seven order of magnitude than the mean free paths due to Coulomb collisions. This may provide a hint to explain why hot and cool gas can co-exist in the intracluster medium in spite of the very short evaporation time scale due to thermal conduction if the conductivity is the classical Spitzer value. Our results suggest that the realization of the global thermal equilibrium is postponed by the local instability which is induced for quicker realization of local thermal equilibrium state in plasmas. The instability provides a new possibility to create and grow cosmic magnetic fields without any seed magnetic field.Comment: Accepted for publication in ApJ: 16 pages, 1figur

Electric Dipolar Susceptibility of the Anderson-Holstein Model

The temperature dependence of electric dipolar susceptibility \chi_P is discussed on the basis of the Anderson-Holstein model with the use of a numerical renormalization group (NRG) technique. Note that P is related with phonon Green's function D. In order to obtain correct temperature dependence of P at low temperatures, we propose a method to evaluate P through the Dyson equation from charge susceptibility \chi_c calculated by the NRG, in contrast to the direct NRG calculation of D. We find that the irreducible charge susceptibility estimated from \chi_c agree with the perturbation calculation, suggesting that our method works well.Comment: 4 pages, 4 figure

Transition density of diffusion on Sierpinski gasket and extension of Flory's formula

Some problems related to the transition density u(t,x) of the diffusion on the Sierpinski gasket are considerd, based on recent rigorous results and detailed numerical calculations. The main contents are an extension of Flory's formula for the end-to-end distance exponent of self-avoiding walks on the fractal spaces, and an evidence of the oscillatory behavior of u(t,x) on the Sierpinski gasket.Comment: 11 pages, REVTEX, 2 postscript figure