Developing Cloud Chambers with High School Students

The result and outcome of the \textit{cloud chamber project}, which aims to develop a cloud chamber useful for science education is reported in detail. A project includes both three high school students and a teacher as a part of Super Science High School (SSH) program in our school. We develop a dry-ice-free cloud chamber using salt and ice (or snow). Technical details of the chamber are described. We also argue how the project have affected student's cognition, motivation, academic skills and behavior. The research project has taken steps of professional researchers, i.e., in planning research, applying fund, writing a paper and giving a talk in conferences. From interviews with students, we have learnt that such style of scientific activity is very effective in promoting student's motivation for learning science.Comment: 9 pages, accepted to the proceedings of APPC12 - the 12th Asia Pacific Physics Conferenc

Two Nucleon-States in a Chiral Quark-Diquark Model

We study the ground and first excited states of nucleons in a chiral quark-diquark model. We include two quark-diquark channels of the scalar-isoscalar and axial-vector-isovector types for the nucleon states. The diquark correlation violating the spin-flavor SU(4)$_{SF}$ symmetry allows to treat the two quark-diquark channels independently. Hence the two states appear as the superpositions of the two quark-diquark channels; one is the nucleon and the other is a state which does not appear in the SU(4)$_{SF}$ quark models. With a reasonable choice of model parameters, the mass of the excited state appears at around 1.5 GeV, which we identify with the Roper resonance N(1440).Comment: 11 pages, 5 figures. Errors are corrected. Conclusions are not affecte

Determining the Θ+\Theta^+ quantum numbers through a Kaon induced reaction

We study the $K^+p\to \pi^+KN$ reaction with kinematical condition suited to the production of the $\Theta^+$ resonance. It is shown that in this reaction with the polarization experiment, a combined consideration of the strength at the peak and the angular dependence of cross section can help determine the $\Theta^+$ quantum numbers.Comment: 4 pages, 3 figures, Talk given at International Workshop PENTAQUARK04 at SPring-8, Japan, July 20-23, 200

Chiral symmetry breaking and stability of strangelets

We discuss the stability of strangelets by considering dynamical chiral symmetry breaking and confinement. We use a $U(3)_{L} \times U(3)_{R}$ symmetric Nambu--Jona-Lasinio model for chiral symmetry breaking supplemented by a boundary condition for confinement. It is shown that strangelets with baryon number $A < 2 \times 10^{3}$ can stably exist. For the observables, we obtain the masses and the charge-to-baryon number ratios of the strangelets. These quantities are compared with the observed data of the exotic particles.Comment: 10 pages, 9 figures, submitted to Physical Review

Nuclear G-Matrix Elements from Nonlocal Potentials

We study effects of nonlocality in the nuclear force on the G-matrix elements for finite nuclei. Nuclear G-matrix elements for \O16 are calculated in the harmonic oscillator basis from a nonlocal potential which models quark exchange effects between two nucleons. We employ a simple form of potential that gives the same phase shifts as a realistic local nucleon potential. The G-matrix elements calculated from the nonlocal potential show moderate increase in repulsion from those derived from the local potential.Comment: 11 page, LaTeX, 2 PS figures, uses epsf.st

A semi-classical over-barrier model for charge exchange between highly charged ions and one-optical electron atoms

Absolute total cross sections for electron capture between slow, highly charged ions and alkali targets have been recently measured. It is found that these cross sections follow a scaling law with the projectile charge which is different from the one previously proposed basing on a classical over-barrier model (OBM) and verified using rare gases and molecules as targets. In this paper we develop a "semi-classical" (i.e. including some quantal features) OBM attempting to recover experimental results. The method is then applied to ion-hydrogen collisions and compared with the result of a sophisticated quantum-mechanical calculation. In the former case the accordance is very good, while in the latter one no so satisfactory results are found. A qualitative explanation for the discrepancies is attempted.Comment: RevTeX, uses epsf; 6 pages text + 3 EPS figures Journal of Physics B (scehduled March 2000). This revision corrects fig.

Composite and elementary natures of a1(1260) meson

We develop a practical method to analyze the mixing structure of hadrons consisting of two components of quark-composite and hadronic composite. As an example we investigate the properties of the axial vector meson a1(1260) and discuss its mixing properties quantitatively. We also make reference to the large Nc procedure and its limitation for the classification of such a mixed state.Comment: 13 pages, 4 figure