Ultra-slow muon facility for surface HFI studies

A concept, a design, a construction and an account of commissioning experiments are given for the recently completed ultra-slow muon facility at the pulsed muon facility of UT-MSL/KEK. The intense (more than 10³/s) slow ⁺ beam with an extremely narrow phase-space volume (0.2 eV×(3 cm)²) to be produced in this facility will open a new muon science including surface physics and chemistry and fundamental atomic physics.Post-doctoral fellow of Swiss National Science Foundation.     

Study of decay mechanisms in B--->Lambdac+ppi- decays and observation of low-mass structure in the Lambdac+p system

Using a sample of 152 x 10(6) BB pairs accumulated with the Belle detector at the KEKB e+e- collider, we study the decay mechanism of three-body charmed decay B- --> Lambdac+ ppi-. The intermediate two-body decay B--->Sigmac (2455)0 p is observed for the first time with a branching fraction of (3.7 +/- 0.7 +/- 0.4 +/- 1.0) x 10(-5) and a statistical significance of 8.4sigma. We also observe a low-mass enhancement in the (Lambdac+p) system, which can be parametrized as a Breit-Wigner function with a mass of (3.35(-0.02)(+0.01) +/-0.02) GeV/c2 and a width of (0.07(-0.03)(+0.04) +/-0.04) GeV/c2. We measure its branching fraction to be (3.9(-0.7)(+0.8) +/- 0.4 +/- 1.0) x 10(-5) with a statistical significance of 6.2sigma. The errors are statistical, systematic, and that of the Lambdac+-->pK- pi+ decay branching fraction.     

Observation of two resonant structures in e+ e- -->pi+ pi- psi(2S) via initial-state radiation at Belle

The cross section for e+ e- --> pi+ pi- psi(2S) between threshold and sqrt[s]=5.5 GeV is measured using 673 fb(-1) of data on and off the Upsilon(4S) resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the pi+ pi- psi(2S) invariant-mass distribution, one at 4361 +/- 9 +/- 9 MeV/c2 with a width of 74 +/- 15 +/- 10 MeV/c2, and another at 4664 +/- 11 +/- 5 MeV/c2 with a width of 48 +/- 15 +/- 3 MeV/c2, if the mass spectrum is parametrized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.     

Modulated inflation

We have studied modulated inflation that generates curvature perturbation from light-field fluctuation. As discussed in previous works, even if the fluctuation of the inflaton itself does not generate the curvature perturbation, fluctuation of a light field may induce fluctuation for the end-line of inflation and this may lead to generation of cosmological perturbation “at the end of the inflation”. Our scenario is different from this kind of modulated scenario, as clearly explained in this Letter by using δN formalism. We also explain the crucial difference from the standard multi-field inflation model. We show concrete examples of the modulated inflation scenario in which large non-gaussianity can be generated. We also discuss the running of the non-gaussianity parameter.     

First observation of B(s)(0) → J/ψη and B(s)(0) → J/ψη'

We report first observations of B(s)(0) → J/ψη and B(s)(0) → J/ψη'. The results are obtained from 121.4 fb(-1) of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e+ e- collider. We obtain the branching fractions B(B(s)(0) → J/ψη)=[5.10±0.50(stat)±0.25(syst)(-0.79)(+1.14)(N(B(s)(*) B(s)(*))]×10(-4), and B(B(s)(0) → J/ψη')=[3.71±0.61(stat)±0.18(syst)(-0.57)(+0.83)(N(B(s)(*) B(s)(*))]×10(-4). The ratio of the two branching fractions is measured to be (B(B(s) → J/ψη'))/(B(B(s) → J/ψη))=0.73±0.14(stat)±0.02(syst).     

Low-Energy Kaon�CNucleon/Nuclei Interaction Studies at DA��NE (SIDDHARTA and AMADEUS Experiments)

The DA??NE electron?Cpositron collider at the Laboratori Nazionali di Frascati of INFN has made available a unique quality low-energy negative kaons ??beam??. The SIDDHARTA experiment used this beam to perform unprecedented precision measurements on kaonic atoms, while the AMADEUS experiment plans to perform in the coming years precision measurements on kaon?Cnuclei interactions at low-energies, in particular to study the kaonic nuclei. The two experiments are briefly presented in this paper.     

Effects of crystalline grain size and packing ratio of self-forming core/shell nanoparticles on magnetic properties at up to GHz bands

Self-forming core/shell nanoparticles of magnetic metal/oxide with crystalline grain size of less than 40 nm were synthesized. The nanoparticles were highly concentrated in an insulating matrix to fabricate a nanocomposite, whose magnetic properties were investigated. The crystalline grain size of the nanoparticles strongly influenced the magnetic anisotropy field, magnetic coercivity, relative permeability, and loss factor (tan δ=μ″/μ′) at high frequency. The packing ratio of the magnetic metallic phase in the nanocomposite also influenced those properties. High permeability with low tan δ of less than 1.5% at up to 1 GHz was obtained in the case of the nanoparticles with crystalline grain size of around 15 nm with large packing ratio of the nanoparticles.