Upper Critical Field Based on the Width of Δ\DeltaH = Δ\DeltaB region in a Superconductor

We studied a method of measuring upper critical field (H$_{c2}$) of a superconductor based on the width of $\Delta$H = $\Delta$B region, which appears in the superconductor that volume defects are many and dominant. Here we present the basic concept and details of the method. Although H$_{c2}$ of a superconductor is fixed according to kind of the superconductor, it is difficult to measure H$_{c2}$ experimentally, and the results are different depending on the experimental conditions. H$_{c2}$ was calculated from the theory that pinned fluxes at volume defects are picked out and move into an inside of the superconductor when their arrangement is the same as that of H$_{c2}$ state of the superconductor. H$_{c2}$ of MgB$_2$ obtained by the method was 65.4 Tesla at 0 K. The reason that H$_{c2}$ obtained by the method is closer to ultimate H$_{c2}$ is based on that $\Delta$F$_{pinning}$/$\Delta$F$_{pickout}$ is more than 4 when pinned fluxes at volume defects of 163 nm radius are picked out. The method will help to find the ultimate H$_{c2}$ of volume defect-dominating superconductors.Comment: 10 pages, 4figure

A Flexible Parametrization of CKM matrix via Singular-Value-Decomposition Method

We investigate a flexible method in which we can test the unitarity of the quark flavor mixing matrix step-by-step. Singular-Value-Decomposition (SVD) techniques are used in analyzing the mixing matrix over a broader parameter region than the unitarity region. Unitary constraints make us extract CP violating properties without any specific parametrization when the magnitudes of at least three mixing matrix elements in three generation quark mixing are given. This method can also be applied to the analysis of lepton flavor mixing, in which only a few moduli are presently measured.Comment: 20 pages, 2 figure

Hierarchical Quark Mixing and Bimaximal Lepton Mixing on the Same Footing

We show that not only the hierarchical quark CKM mixing matrix but also the "bimaximal" lepton flavor mixing matrix can be derived from the same mass matrix ansatz based on the broken permutation symmetry, by assuming the hierarchy of neutrino masses to be $m_1\simeq m_2 <<m_3$. We also reproduce the recently measured angle of unitary triangle, $\sin 2\beta$, as well as all the observed experimental values of $V_{{\tiny CKM}}$ of the quark CKM matrix. And we predict Jarlskog rephasing invariant quantity, $J_{{\tiny CP}} \simeq 0.18 \times 10^{-4}$, and the upper bound of the same quantity in the lepton sector, $J^l_{{\tiny CP}} \leq 0.012$, which may be indeed large enough to generate the lepton number violation of the universe.Comment: 12 Pages, LaTeX, no figures, corrected hep-ph number and a PACS numbe

Full Numerical Estimation of Neutrino Mixing Parameters from Solar Neutrino Data

We have numerically computed survival probabilities of solar neutrinos interacting with matter via MSW mechanism in the full three generation formalism with $\Delta m^2_{23}=2.2\times 10^{-3}$ eV$^2$. For $\theta_{13} \lesssim 30^{\circ}$, we confirm the two regions found in the two generation case, (1) with the most likelyhood, small $\sin^2(2\theta_{12}) \sim 0.006$, (2) with less likelyhood, large $\sin^2(2\theta_{12}) \gtrsim 0.5$. For $\theta_{13}\gtrsim 30^{\circ}$, we find an additional region, (3) with even less likelyhood, $10^{-5} < \Delta m^2_{12}< 10^{-4}$ eV$^2$ and/or $10^{-4} < \sin^2(2\theta_{12}) < 0.5$. Assuming that the case (1) is valid, we predict that $\theta_{13} \simeq 15^\circ$.Comment: 4 pages, 1 postscript figure, 1 gif figur

On Lepton Flavor Violation in Tau Decays

We study lepton flavor violation (LFV) in tau decays induced by heavy Majorana neutrinos within two models: (I) the Standard Model with additional right-handed heavy Majorana neutrinos, i.e., a typical seesaw-type model; (II) the Standard Model with left-handed and right-handed neutral singlets, which are inspired by certain scenarios of SO(10)models and heterotic superstring models with E_6 symmetry. We calculate various LFV branching ratios and a T-odd asymmetry. The seesaw Model I predicts very small branching ratios for LFV processes in most of the parameter space, although in a very restricted parameter region it can reach maximal branching ratios Br(tau to mu gamma) approx 10^-9 and Br(tau to 3mu) approx 10^-10. In contrast, Model II may show branching ratios Br(tau to e gamma) approx 10^-8 and Br(tau to 3e) < 10^-9, over a sizable region of the parameter space, large enough to be tested by experiments in the near future.Comment: 19 pages, 5 ps-figures; minor changes, accepted for publication in Phys. Rev.

Is CDF large pTp_T anomaly from virtual SUSY threshold effects?

Talk is given at the YITP International Workshop -- `Recent Developments in QCD and Hadron Physics'. Recent CDF data of the inclusive jet cross section shows anomalous deviation around large transverse momentum $p_{T}(j)\approx 200 \sim 350$ GeV. Is it possible to interpret the anomaly in terms of virtual SUSY effects. The answer is `NO', because we find that the virtual SUSY loop interference effects are too small to explain the CDF data.Comment: 6 pages(LaTeX), 2 Postscript figures, uses revtex.sty and axodraw.st

Electroweak Discussion Section Summary

I summarize our work of electroweak discussion section held at the 14th International Workshop on Weak Interactions and Neutrinos. We discussed about a few physics topics related to electroweak interactions, including $B$ and $K$ physics and weak flavor physics.Comment: 18 pages (1 Figure not included), YUMS 93-25/SNUTP 93-7

A Model-independent Way to Measure ∣Vub/Vcb∣|V_{ub}/V_{cb}|

We propose a new model-independent method, to determine the ratio $|V_{ub}/V_{cb}|$, which is theoretically described by the phase space factor and the well-known perturbative QCD correction only. We explore the possible experimental options: the measurement of inclusive hadronic invariant mass distributions. We also discuss the relevant experimental backgrounds.Comment: 10 pages, no figures. Talk given at Asian Science Seminar (KOSEF-JSPS Winter School), Seoul Korea, on February 21 - 28 (1996). Proceedings will be published by J. Kor. Phys. Soc. (1996

Quantum Mechanics of Neutrino Oscillations

We present a simple but general treatment of neutrino oscillations in the framework of quantum mechanics using plane waves and intuitive wave packet principles when necessary. We attempt to clarify some confusing statements that have recently appeared in the literature.Comment: 13 pages, no figure

Yang-Yang Anomalies and Coexistence Diameters: Simulation of Asymmetric Fluids

A general method for estimating the Yang-Yang ratio, ${\cal R}_{\mu}$, and the coexistence-curve diameter of a model fluid via Monte Carlo simulations is presented on the basis of data for a hard-core square-well (HCSW) fluid and the restricted primitive model (RPM) electrolyte. The isothermal minima of $Q_{L}\equiv^{2}_{L}/_{L}$ are evaluated at $T_{c}$ in an $L\times L\times L$ box where $m = \rho - _{L}$ is the density fluctuation. The ``complete'' finite-size scaling theory for the $Q_{\scriptsize min}^{\pm}(T_{c};L)$ incorporates pressure mixing in the scaling fields, thereby allowing for a Yang-Yang anomaly.Comment: Submitted for publication in Phys. Rev.