Measurement of B(0)(d)-B_(0)(d) mixing rate from the time evolution of dilepton events at the upsilon(4S)

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.     

Simultaneous irradiation of ultrasound and UV light. Ultrasonic acceleration of the photochemical disappearance of 4,4'-dihalogenated benzils in 1,4-dioxane

Irradiation of ultrasound accelerated the rate of the photochemical disappearance of 4,4'-dihalogenated benzils in 1,4-dioxane in the order of halogen = I, Br > Cl > F. 4,4'-dimethoxy and unsubstituted benzils did not show acceleration. Possible mechanisms of the acceleration are discussed.     

New classes of quasicrystals and marginal critical states

One-dimensional quasilattices, namely, the geometrical objects that represent quasicrystals, are classified into mutual local-derivability (MLD) classes. Besides the familiar class, there exist an infinite number of new MLD classes, and different MLD classes are distinguished by the inflation rules of their representatives. It has been found that electronic properties of a new MLD class are characterized by the presence of marginal critical states, which are considered to be nearly localized states.     

Gamow-teller strengths of the inverse beta transition 176Yb-->176Lu for spectroscopy of proton-proton and other sub-MeV solar neutrinos

Discrete Gamow-Teller (GT) transitions 176Yb-->176Lu at low excitation energies have been measured via the ( 3He,t) reaction at 450 MeV and at 0 degrees. For 176Yb, two low-lying states are observed, setting low thresholds Q(nu) = 301 and 445 keV for neutrino ( nu) capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low Q(nu) in Yb-Lu indicate that Yb-based nu detectors are well suited for a direct measurement of the sub-MeV solar electron-neutrino ( nu(e)) spectrum including pp neutrinos.     

Magnetically recoverable osmium catalysts for dihydroxylation of olefins

We prepared magnetically recoverable osmium catalysts by use of magnetite, quaternary ammonium salts, and potassium osmate(VI), and applied them to the dihydroxylation of olefins. By employing 2 mol% of the magnetic osmium catalyst, the dihydroxylation reaction proceeded smoothly to provide the corresponding vicinal diol in a good chemical yield. The osmium catalyst was readily recovered by use of an external magnet, and was reused repeatedly.     

Balanced decomposition of a vertex-colored graph

A balanced vertex-coloring of a graph G is a function c from V(G) to {−1,0,1} such that ∑{c(v):v∈V(G)}=0. A subset U of V(G) is called a balanced set if U induces a connected subgraph and ∑{c(v):v∈U}=0. A decomposition V(G)=V₁∪?∪V_r is called a balanced decomposition if V_i is a balanced set for 1≤i≤r.In this paper, the balanced decomposition number f(G) of G is introduced; f(G) is the smallest integer s such that for any balanced vertex-coloring c of G, there exists a balanced decomposition V(G)=V₁∪?∪V_r with |V_i|≤s for 1≤i≤r. Balanced decomposition numbers of some basic families of graphs such as complete graphs, trees, complete bipartite graphs, cycles, 2-connected graphs are studied.     

Photoconductive properties of titanium dioxide film modified by femtosecond laser irradiation

Titanium dioxide (TiO₂) films were irradiated with a femtosecond laser to alter their photoconductive properties. The laser wavelength and pulse duration were 775 nm and 150 fs, respectively. The TiO₂ films irradiated with the femtosecond laser were darkened without changing the topography of the TiO₂ film surface. The electrical resistances of the films as a function of time were measured under visible-light illumination. The transient electrical resistances decreased as time was increased after turning on the light. There were two stages in the reduction process of the electrical resistance.