K.-I. Kubo

G-matrix effective interaction with the paris potential

Abstract An effective interaction is derived by fitting the oscillator matrix elements of the sum of the OBEP functions to the G -matrix elements derived from the Paris nucleon-nucleon interaction. The functional form, the mass dependence and the ambiguities of the effective interaction are discussed. For the application of the present effective interaction, we study the mass dependence of the G -matrices and estimate the Landau-Migdal parameter g ′. We have obtained reasonable results for these cases.

Optical-potential description of antiproton-nucleus scattering at 46.8 MeV

Abstract Optical-potential analyses of the p − 12 C scattering at 46.8 MeV are presented and the existence of the continuous-parameter ambiguity is demonstrated. The elastic p - polarization is calculated and compared with the p-polarization at the same energy. The impact parameter of the antiproton absorbed is obtained from the eikonal model using the N N two-body forward-scattering amplitude.

The 58Ni(p, α) reaction mechanism through a study of the analyzing power

Abstract Analyzing powers of the 58 Ni(p, α) reaction at E p = 22 and 72 MeV have been calculated for transitions to the ground state of 55 Co and to excited states in the continuum. DWBA calculations have been performed with both the α knock-out and triton pick-up models. The analyzing power at 72 MeV in the continuum was calculated with the statistical multistep direct theory. It is found that while the g.s. transition is dominated by the triton pick-up process, the analyzing power in the continuum can only be reproduced by an α knock-out mechanism. Some general considerations on the interplay between these two mechanisms and on the consistency with results obtained in the past with semiclassical preequilibrium models are made.

Pionic atoms of unstable nuclei

Abstract High-energy heavy-ion collisions (∼GeV/N) open up a possibility to produce pionic atoms of unstable nuclei. We study the neutron number dependence of energy shifts and widths of pionic atoms in wide mass regions using standard pion-nucleus optical potentials. Two widely used optical potentials provide appreciably different results as the neutron number of deviates from the ones of stable nuclei.

Nuclear-matter radii of 7Be and 7Li and astrophysical S-factors for radiative alpha-capture reactions

Abstract The nuclear-matter radii of 7 Be and 7 Li measured in high-energy heavy-ion reactions have been calculated and applied to the estimate of astrophysical S-factors for the 3 He(α,γ) 7 Be and 3 G(α,γ) 7 Li reactions. The absolute S (O) values in the KeV b are constrained to be 0.36 S (0) S (0) 3 He(α,γ) 7 Be and 3 H(α,γ) 7 Li reactions, respectively.

A strong absorptive potential as the preferential antiproton-nucleus optical potential

Abstract The p-nucleus interaction is studied for p 12 C scattering data measured at 46.8 MeV. It is found that strong damping of the nuclear interior participation is a necessary condition to describe consistently both elastic and inelastic p-nucleus scattering.

Hadron Spin Polarization Produced by a Dynamical Spin-Orbit Interaction

The spin observables in high energy hadron reactions, such as spin polarization, analyzing power and spin depolarization, are of increasing interest for extracting precise information about the structure functions of the quark parton in hadrons 1) and even in leptons and photon. 2) Almost two decades ago, DeGrand and Miettinen 3) proposed a kinematic model to predict the sign and to estimate the order of magnitude of the spin observables produced in inclusive high energy hadron collisions. In their model, they assumed an empirical rule which can be briefly expressed as, “fast spin up and slow spin down.” This rule refers to the preferential direction of spin polarization of the produced hadrons in relation to the velocity of participating partons. From the momentum distribution functions of the quark parton in hadrons, it is known that the valence parton has a larger velocity while the sea parton has a smaller velocity. DeGrand and Miettinen found systematic occurrence in the empirical data of spin polarization such that the fast (slow) parton(s) mostly carries up (down) spin; that is the fast (slow) parton(s) preferentially produces hadrons with spin-up (spin-down). They also showed that a spin-orbit interaction results from this rule through Thomas precession of the spin carrier parton(s), and they concluded that this is the cause of the observed spin asymmetries. Recently, we proposed a general formulation 4) to describe the spin observables of hadrons inclusively produced in high-energy hadron collisions, and we showed that our model, called the microscopic quark recombinaation (QRC) model, is successful in reproducing the experimentally obtained spin observables. In our formulation, we do not assume the DeGrand-Miettinen (DM) empirical rule, but, rather, we start from a relativistic expression for the transition amplitude of the participating quark parton’s distribution functions in hadrons. The QRC formulation provides spin observables as functions of the transverse momentum PT and Feynman’s variable xF. This is an advantage of the model, and it is extremely useful for extracting

The (p, α) reaction (I). The left-right asymmetry, the j-dependence and the cross-section magnitude

Abstract The universal phase relations existing in the (p, α) left-right ayrametry are summarized. The features are found to be useful to interpret the j-dependence of the cross-section angular distributions. The theoretical (p, α) cross section has been a subject of long discussion since some of them are 100 or 1000 times smaller compared with the measurements. Recently a reasonable order of the calculated cross section was reported but no detail of the theoretical analysis. We review the situations and report our first result for a systematic study of the (p, α) reaction mechanisms.

Dynamical polarization potential and ACa+16O(A = 40, 42, 44 and 48) optical model potentials

Abstract Dynamical polarization potentials induced by both inelastic and nucleon transfer excitations are formulated and numerically studied. The results are applied to a systematic study of the phenomenological optical potentials found in 16 O+Ca isotopes at 56 MeV. The change in the absorptive potentials as a function of mass number is well understood by this method of considering the difference in the nuclear reaction dynamics.

High energy hadron spin observables—Microscopic QRC model and spin asymmetry—

We briefly review concept of the quark recombination (QRC) model and a general success of the model. To solve the existing problem, so called anomalous spin observables, in the high energy hyperon spin phenomena, we propose a mechanism; the primarily produced quarks, which are predominantly u and d quarks, act as the leading partons to form the hyperons. Extension of the quark recombination concept with this mechanism is successful in providing a good account of the anomalous spin observables. Another kind of anomaly, the non-zero analyzing power and spin depolarization in the Λ hyperon productions, are also discussed and well understood by the presently proposed mechanism. Recently, a further difficulty was observed in an exclusive ΛK+p production and we will indicate a possible diagram for resolving it.