Observation of B+ --> K0K+ and B0 --> K0K0

We report observations of the b --> d penguin-dominated decays B+ --> K0K+ and B0 --> K0K0 in 316 fb(-1) of e+ e- collision data collected with the BABAR detector. We measure the branching fractions B(B+ --> K0K+) = (1.61+/-0.44+/-0.09) x 10(-6) and B(B0 --> K0K0 = (1.08+/-0.28+/-0.11) x 10(-6) and the CP-violating charge asymmetry A(CP)(K0K+) = 0.10+/-0.26+/-0.03. Using a vertexing technique previously employed in several analyses of all-neutral final states containing kaons, we report the first measurement of time-dependent CP-violating asymmetries in B0 --> K(S)0K(S)0, obtaining S = -1.28(-0.73-0.16)(+0.80+0.11) and C = -0.40+/-0.41+/-0.06. We also report improved measurements of the branching fraction B(B+ --> K0 pi+) = (23.9+/-1.1+/-1.0) x 10(-6) and CP-violating charge asymmetry A(CP)(K0 pi+) = -0.029+/-0.039+/-0.010.     

Results from Super-Kamiokande and K2K

Results from Super-Kamiokande-I’s entire 1496 live days of solar neutrino data are presented, including the absolute flux, energy spectrum, zenith angle (day/night) and seasonal variation. The possibility of MSW and vacuum oscillations is discussed in light of these results. Results from the first 1289 days of Super-K-I’s atmospheric neutrino analysis are also presented, including the evidence for ν_μ →ν _τ oscillations, against ν_μ → ν_sterile oscillations, and the current limits on proton decay. Finally, results based on 56 × 10¹⁹ protons on target are given for the K2K long-baseline neutrino oscillation experiment.     

Two-hole strengths in K from the K(He, αK reaction

States in ³⁸K up to 7.13 MeV excitation have been studied using the 21 MeV ³He⁺⁺ beam of a tandem Van de Graaff and the ³⁹K(³He, α) reaction. Charged particles were analysed by a split-pole magnetic spectrograph equipped with a telescope arrangement of proportional counters for position and energy-loss measurement.     

Strong binding and shrinkage of single and double nuclear systems (K?pp,K?ppn,K?K?p and K?K?pp) predicted by Faddeev-Yakubovsky calculations

Non-relativistic Faddeev and Faddeev-Yakubovsky calculations were made for K⁻pp, K⁻ppn, K⁻K⁻p and K⁻K⁻pp kaonic nuclear clusters, where the quasi bound states were treated as bound states by employing real separable potential models for the K⁻-K⁻ and the K⁻-nucleon interactions as well as for the nucleon-nucleon interaction. The binding energies and spatial shrinkages of these states, obtained for various values of the interaction, were found to increase rapidly with the interaction strength. Their behaviors are shown in a reference diagram, where possible changes by varying the interaction in the dense nuclear medium are given. Using the Λ(1405) ansatz with a PDG mass of 1405 MeV/c² for K⁻p, the following ground-state binding energies together with the wave functions were obtained: 51.5 MeV (K⁻pp), 69 MeV (K⁻ppn), 30.4 MeV (K⁻K⁻p) and 93 MeV (K⁻K⁻pp), which are in good agreement with previous results of variational calculation based on the Akaishi-Yamazaki coupled-channel potential. The K⁻K⁻pp state has a significantly increased density where the two nucleons are located very close to each other, in spite of the inner NN repulsion. Relativistic corrections on the calculated non-relativistic results indicate substantial lowering of the bound-state masses, especially of K⁻K⁻pp, toward the kaon condensation regime. The fact that the recently observed binding energy of K⁻pp is much larger (by a factor of 2) than the originally predicted one may infer an enhancement of the interaction in dense nuclei by about 25% possibly due to chiral symmetry restoration. In this respect some qualitative accounts are given based on “clearing QCD vacuum” model of Brown, Kubodera and Rho.     

Measurement of K shell fluorescence cross-section of Ca and K compounds

The cross-section for Ca and K compounds were determined by measuring the KX-ray yields from targets excited 5.96 keV photons and using theoretical K shell photoionization cross-section. By comparing the experimental results with relativistic Hartree-Fock calculation, a good agreement has been obtained considering the experimental errors.     

Study of Kπ scattering using the reactions K±p → K±π+nand K±p → K±π−Δ ++at 13 GeV

An elastic Kπ partial-wave analysis is presented. It is based on high statistics data for the reactions $\text{K}{}^{\mathrm{\pm }}\text{p}\text{→}\text{K}{}^{\mathrm{\pm }}\text{π}{}^{\mathrm{+}}\text{n}\text{and K}{}^{\mathrm{\pm }}\text{p}\text{→}\text{K}{}^{\mathrm{\pm }}\text{π}{}^{\mathrm{?}}\text{Δ}{}^{\mathrm{++}}\text{at}\text{13}\text{GeV}$ obtained in a spectrometer experiment performed at SLAC. For each reaction, a t-dependent parametrization of the production amplitudes provides information on both the Kπ mass dependence of the production mechanisms and on Kπ scattering. Knowledge of the t-dependence then allows a calculation of the Kπ partial-wave amplitudes for Kπ masses from 0.7 to 1.9 GeV. The results of such analyses using data for (i) the neutral recoil reactions, (ii) the Δ⁺⁺ recoil reactions, and (iii) both neutron and Δ⁺⁺ recoil reactions simultaneously, are presented. Besides the leading J^P = 1^?, 2⁺, and 3^? resonances at M_Kπ = 0.896, 1.434, and 1.78 GeV, there is evidence in two of the four possible partial-wave solutions for a broad P-wave resonant-like structure in the region of 1700 MeV. The $\text{I =}\text{1}\text{2}$ S-wave magnitude rises slowly and smoothly to a maximum near 1400 MeV, but then decreases rapidly between 1400 and 1600 MeV. This structure is strongly indicative of an S-wave resonance near 1450 MeV. The charge-two Kπ reaction is dominated by S-wave scattering with a total cross section decreasing from 4 mb at 0.9 GeV to 2 mb at 1.5 GeV. Both the $\text{I =}\text{1}\text{2}$ S-wave below 1400 MeV and the $\text{I =}\text{3}\text{2}$ S-wave are well described by an effective range parametrization.     

Large strong phases and CP violation in the annihilation processes B̄0→K+K-, K*±K∓, K*+K*-

The strong phases and CP violation in the rare B̄⁰→K⁺K^-, K^*±K^∓, K^*+K^*- decays are investigated. As these decays proceed only via annihilation type diagrams in the standard model (SM), a dynamical gluon mass is introduced to avoid the infrared divergence in the soft endpoint regions. The Cutkosky rule is adopted to deal with a physical-region singularity of the on-mass-shell quark propagators, which leads to a big imaginary part and hence a large strong phase. As a consequence, large CP asymmetries are predicted in those decay modes due to a big interference between the annihilation amplitudes from penguin and tree operators, which may be tested in future more precise experiments. PACS 13.25.Hw; 11.30.Er; 12.38.Bx     

Elastic constants of sodium chlorate from 77 K to 350 K

The elastic constantsC ₁₁,C ₁₂ andC ₄₄ of sodium chlorate single crystal have been evaluated using 10 MHz ultrasonic pulse echo superposition technique. The values areC ₁₁=4.90,C ₁₂=1.39,C ₄₄=1.17 (× 10¹⁰ N/m ²) at 298 K and 6.15, 2.16, 1.32 (×10¹⁰ N/m ²) at 77 K. The data agree well with the values measured earlier up to 223 K. Brief mention is also made of the low temperature bonding problems in these soft crystals.     

Spectroscopy of 41K by thermal neutron capture in 40K

The γ-ray spectrum emitted after thermal neutron capture in ⁴⁰K has been studied at the ILL high flux reactor with curved crystal Bragg, pair and Ge(Li) spectometers. 585 transitions were assigned to the reaction ⁴⁰K(n, γ)⁴¹K and 490 of them were placed into a ⁴¹K level scheme; 68 new states are proposed. On the basis of γ-ray branches to states with established spin and parity, many new spin-parity assignments were made. The level energies up to 4 MeV were measured with a precision of 8–50 eV relative to the 411.8 keV ¹⁹⁸Au standard, those above 4 MeV with a precision of 50–100 eV. The spin of the capture state was found to be $\text{I =}\text{7}\text{2}$; the neutron binding energy was determined to E_B = 10095.25(10) keV. The level density of $\text{I}{}^{\mathrm{\pi }}\text{=}\text{5}\text{2}{}^{\mathrm{\pm }}\text{,}\text{7}\text{2}{}^{\mathrm{\pm }}\text{,}\text{9}\text{2}{}^{\mathrm{\pm }}$ states was analyzed in terms of the constant-temperature Fermi gas model. It was shown that in this spin window the level scheme is almost complete up to an excitation energy of 5 MeV.     

Isothermal bulk modulus of solid xenon for zero pressure at 4.2 K, 65 K and 77 K

An interferometric method has been used to measure the isothermal bulk modulus (the reciprocal of the compressibility) of solid xenon at zero pressure for several temperatures. It is the first time that an elastic constant of this substance has been measured at a temperature below 10 K. The smoothed results are (37.9 ± 0.5) kbars at 4.2 K, (29.6 ± 0.5) kbars at 65.6 K, and (28.2 ± 0.5) kbars at 77 K.     

K and K* Exchange Effects in Lambda Hypernuclei

We study the effects of K and K^＊ exchange between the A hyperon and the nucleon in a A hypernueleus, where the nuclear core is described by a successful relativistic mean-field （RMF） model. In general, K and K^＊ are responsible for strangeness exchange in the one-boson-exchange potential model, which are absent in the RMF calculation. We investigate the contribution of Fock terms derived from K and K^＊ exchange. We use a pseudovector coupling for K exchange, which is found to provide a repulsive potential for the A particle in hypernuclei. Both vector and tensor couplings for K^＊ exchange are taken into account, whose combined effect on the A single-particle energy is found to be small.     

Branching fractions and CP asymmetries in B0-->K+ K- K0 S and B+-->K+ K0 S K0 S

We measure the branching fractions and CP asymmetries in the decays B0-->K(+)K(-)K(0)(S) and B+-->K(+)K(0)(S)K(0)(S) using a sample of approximately 122x10(6) BB pairs collected by the BABAR detector. From a time-dependent analysis of the K(+)K(-)K(0)(S) sample that excludes phiK(0)(S), the values of the CP-violation parameters are S=-0.56+/-0.25+/-0.04 and C=-0.10+/-0.19+/-0.10, where the first uncertainty is statistical and the second is systematic. We confirm that the final state is nearly purely CP even and extract the standard model parameter sin(2beta=0.57+/-0.26+/-0.04(+0.17)(-0) where the last error is due to uncertainty on the CP content. We present the first measurement of the CP-violating charge asymmetry A(CP)(B+-->K(+)K(0)(S)K(0)(S))=-0.04+/-0.11+/-0.02. The branching fractions are B(B0-->K+K-K0)=(23.8+/-2.0+/-1.6)x10(-6) and B(B+-->K(+)K(0)(S)K(0)(S))=(10.7+/-1.2+/-1.0)x10(-6).     

Mechanical stabilities of K4 carbon and K4-like NaC2

The mechanical stabilities of K₄ carbon and K₄-like NaC₂ have been studied by performing first-principle calculations. Total energies as functions of isotropic deformations and volume-conserving tetragonal and trigonal deformations have been calculated. For K₄ carbon, the total energy shows a minimum for isotropic and trigonal deformations, but exhibits maxima for tetragonal deformation. In contrast, the total energy of K₄-like NaC₂ shows a minimum under all three deformations. These results indicate that K₄ carbon is not a metastable phase, but that K₄-like NaC₂ is a metastable phase. In addition, the heat of formation of K₄-like NaC₂ is discussed.     

Magnetic orientation of carbon nanotubes at temperatures of 231 K and 314 K

Carbon nanotubes were placed in magnetic fields of  80.0 kOe at temperatures of 231 K and 314 K. Scanning electron microscopy showed that nanotubes were oriented with the tube axis parallel to the fields. It was also observed that the probability of the orientation became higher, when the temperature was raised from 231 K to 314 K. The anisotropy in the susceptibilities parallel X∥ and perpendicular X _⊥ to the tube axis is suggested to increase with rise in temperature: X∥ ? X⊥ = (4 ± 2) × 10^?6 emu mol^?1 (per mol of carbon atoms) at 231 K and X∥ ? X⊥ = (45 ± 27) × 10^?6 emu mol^?1 at 314 K.     

Results from solar, atmospheric and K2K experiments and future possibilities with T2K

Recent results from solar, reactor, atmospheric and long baseline (K2K) experiments are discussed. With the improved data statistics and analyses, our knowledge on the neutrino masses and mixing angles are steadily improving. T2K is the next generation neutrino oscillation experiment between J-PARC in Tokai and Super-Kamiokande. This experiment will start in 2009. This experiment is expected to improve the current knowledge on the neutrino masses and mixings substantially.     

K− mass and K− polarizability from kaonic atoms

The K^? mass was determined from kaonic atomic X-rays from Au and Ba to be 493.691 ± 0.040 MeV. An upper limit for the polarizability of the K^? was found to be 0.020 fm³ at 90% confidence.