Observation of direct CP violation in B0 --> pi+pi- decays and model-independent constraints on the quark-mixing angle phi2

We report a new measurement of the time-dependent CP-violating parameters in B(0)-->pi(+)pi(-) decays with 535 x 10(6) BB pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider operating at the Upsilon(4S) resonance. We find 1464+/-65 B(0)-->pi(+)pi(-) events and measure the CP-violating parameters S(pipi)=-0.61+/-0.10(stat)+/-0.04(syst) and A(pipi)=+0.55+/-0.08(stat)+/-0.05(syst). We observe large direct CP violation with a significance greater than 5 standard deviations for any S(pipi) value. Using isospin relations, we measure the Cabibbo-Kobayashi-Maskawa quark-mixing matrix angle phi(2)=(97+/-11) degrees for the solution consistent with the standard model and exclude the range 11 degrees 相似文献   

Observation of the decay B(0)-->J/psieta

We report the first observation of B(0)-->J/psieta decay. These results are obtained from a data sample that contains 449 x10(6) BB[over] pairs accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We observe a signal with a significance of 8.1 sigma and obtain a branching fraction of (9.5+/-1.7(stat)+/-0.8(syst)) x 10(-6).     

Polarization modulation imaging ellipsometer

The polarization modulation technique was successfully combined with parallel synchronous detection using a switching light source and a CCD camera to realize full-frame measurement of ellipsometric parameters. The detected thickness of a monolayer film of n-octadecylsiloxane agreed well with theoretical and reported experimental values. The thickness resolution for imaging and the temporal noise in parallel thickness measurements were smaller than +/-0.1 nm and smaller than +/-0.02 nm, respectively.     

Magnetic moment of short lived β-emitter 24mAl

The magnetic moment of short lived β-emitter ^24mAl (426 keV, I ^π ?=?1^?+?, T _1/2?=?131 ms) has been measured by means of β-NMR technique, for the first time. From the β-NMR spectrum, the magnetic moment was determined as $\left| {\upmu}\left( ^{\rm 24m}{\rm Al} \right) \right|=\left( {2.99\pm 0.09} \right){\upmu}_{\rm N}$ . Combined with the known magnetic moment of the mirror partner ^24mNa, the expectation value of <?S _z?> is obtained to be (0.08 ± 0.12). These values are reproduced well by the shell model calculation.     

Polarization of 23Ne, 24m,25Al and 28P produced through single nucleon pickup and charge-exchange reactions at 100 AMeV

We measured the polarization of the $\upbeta $ -emitting ²³Ne (I ^π ?= 5/2^?+?, T _1/2?= 37.24 s) and ²⁵Al(I ^π ?= 5/2^?+?, T _1/2?= 7.18 s) produced through the one nucleon pickup reactions and ^24mAl(I ^π ?= 1^?+?, T _1/2?= 131 ms, E _ex?= 426 keV) and ²⁸P(I ^π ?= 3^?+?, T _1/2?= 270 ms) produced through charge-exchange reactions in the intermediate energy heavy ion collisions. We compared them with those from the projectile fragmentation process. The larger polarization seems to persistently be positive throughout the momentum distribution, and sharper momentum distributions suggest that nuclear friction mechanism is responsible for the polarization phenomena.     

Search for the CP-violating decays Upsilon(4S)-->B0B0-->J/psiKS0+J/psi(etac)KS0

We report the first search for CP-violating decays of the Upsilon(4S) using a data sample that contains 535 x 10(6) Upsilon(4S) mesons with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. A partial reconstruction technique is employed to enhance the signal sensitivity. No significant signals were observed. We obtain an upper limit of 4 x 10(-7) at the 90% confidence level for the branching fractions of the CP violating modes, Upsilon(4S)-->B(0)B(0)-->J/psiK(S)(0)+J/psi(eta(c))K(S)(0). Extrapolating the result, we find that an observation with 5sigma significance is expected with a 30 ab(-1) data sample, which is within the reach of a future super B factory.     

Search for B --> h(*)nunu[over ] decays at Belle

We present a search for the rare decays B --> h(*)nunu[over ], where h(*) stands for a light meson. A data sample of 535 x 10{6} BB[over ] pairs collected with the Belle detector at the KEKB e{+}e{-} collider is used. Signal candidates are required to have an accompanying B meson fully reconstructed in a hadronic mode and signal side particles consistent with a single h(*) meson. No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level. The limits on B{0} --> K{*0}nunu[over ] and B{+} --> K{+}nunu[over ] decays are more stringent than the previous constraints, while the first searches for B{0} --> K{0}nunu[over ], pi{0}nunu[over ], rho{0}nunu[over ], varphinunu[over ] and B{+} --> K{*+}nunu[over ], rho{+}nunu[over ] are reported.     

Solving the Schrödinger equation of atoms and molecules without analytical integration based on the free iterative-complement-interaction wave function

A local Schr?dinger equation (LSE) method is proposed for solving the Schr?dinger equation (SE) of general atoms and molecules without doing analytic integrations over the complement functions of the free ICI (iterative-complement-interaction) wave functions. Since the free ICI wave function is potentially exact, we can assume a flatness of its local energy. The variational principle is not applicable because the analytic integrations over the free ICI complement functions are very difficult for general atoms and molecules. The LSE method is applied to several 2 to 5 electron atoms and molecules, giving an accuracy of 10(-5) Hartree in total energy. The potential energy curves of H2 and LiH molecules are calculated precisely with the free ICI LSE method. The results show the high potentiality of the free ICI LSE method for developing accurate predictive quantum chemistry with the solutions of the SE.     

Interference between Compton scattering and x-ray parametric down-conversion

Parametric down-conversion of x rays into extreme ultraviolet and accompanying nonlinear x-ray diffraction were investigated both theoretically and experimentally. The theory predicted a rocking curve having a Lorentzian signal peak; however, the experiments revealed a peak followed by an unexpected dip. Together with the scattering angle dependence of the signal, the experimental results implied a possibility of interference between the Compton scattering and the parametric down-conversion. The similarity to the Fano effect is discussed.     

Medium-range fluctuations accompanying the metal-nonmetal transition in expanded fluid hg

We have carried out small angle x-ray scattering experiments of expanded fluid Hg in the metal-nonmetal (M-NM) transition region around 9.0 g cm(-3). Increase of small angle scattering intensity following the Ornstein-Zernike equation is clearly observed in the M-NM transition region as well as near the liquid-vapor critical point at 5.8 g cm(-3). The short-range correlation length, R, becomes twice as large in the M-NM transition region as in the critical region. The enhancement of R in expanded fluid Hg suggests a new type of fluctuations reflecting a first-order M-NM transition.