Polarization phenomena in hyperon-nucleon scattering

We investigate polarization observables in hyperon-nucleon scattering by decomposing scattering amplitudes into spin-space tensors, where each component describes scattering by corresponding spin-dependent interactions, so that contributions of the interactions in the observables are individually identified. In this way, for elastic scattering we find some linear combinations of the observables sensitive to particular spin-dependent interactions such as symmetric spin-orbit (LS) interactions and antisymmetric LS ones. These will be useful to criticize theoretical predictions of the interactions when the relevant observables are measured. We treat vector analyzing powers, depolarizations, and coefficients of polarization transfers and spin correlations, a part of which is numerically examined in $\Sigma^{+} p$ scattering as an example. Total cross sections are studied for polarized beams and targets as well as for unpolarized ones to investigate spin dependence of imaginary parts of forward scattering amplitudes.Comment: 15 pages, 8 figure

Central and tensor components of three-nucleon forces in low-energy proton-deuteron scattering

Contributions of three-nucleon forces (3NF) to proton-deuteron scattering observables at energies below the deuteron breakup threshold are studied by solving the Faddeev equation that includes the Coulomb interaction. At E_p=3.0 MeV, we find that the central part of a two-pion exchange 3NF removes the discrepancy between measured cross sections and the calculated ones by two-nucleon forces, and improves the agreement with T_{22} experimental data. However, the tensor part of the 3NF fails in reproducing data of the analyzing power T_{21} by giving worse agreement between the measured and the calculated. Detailed examinations of scattering amplitudes suggest that a P-wave contribution in spin quartet tensor amplitudes has unsuitable sign for reproducing the T_{21} data.Comment: 6 pages, 6 figure

Fine-Scale Spatial Organization of Face and Object Selectivity in the Temporal Lobe: Do Functional Magnetic Resonance Imaging, Optical Imaging, and Electrophysiology Agree?

The spatial organization of the brain's object and face representations in the temporal lobe is critical for understanding high-level vision and cognition but is poorly understood. Recently, exciting progress has been made using advanced imaging and physiology methods in humans and nonhuman primates, and the combination of such methods may be particularly powerful. Studies applying these methods help us to understand how neuronal activity, optical imaging, and functional magnetic resonance imaging signals are related within the temporal lobe, and to uncover the fine-grained and large-scale spatial organization of object and face representations in the primate brain

Spin observables in nucleon-deuteron scattering and three-nucleon forces

Three-nucleon forces, which compose an up-to-date subject in few-nucleon systems, provide a good account of the triton binding energy and the cross section minimum in proton-deuteron elastic scattering. However, three-nucleon forces do not explain spin observables such as the nucleon and deuteron analyzing powers, suggesting serious defects in their spin dependence. We study the spin structure of nucleon-deuteron elastic amplitudes by decomposing them into spin-space tensors and examine effects of three-nucleon forces to each component of the amplitudes obtained by solving the Faddeev equation. Assuming that the spin-scalar amplitudes dominate the others, we derive simple expressions for spin observables in the nucleon-deuteron elastic scattering. The expressions suggest that a particular combination of spin observables in the scattering provides direct information on scalar, vector, or tensor component of the three-nucleon forces. These effects are numerically investigated by the Faddeev calculation

CO Binding onto Heterometals of [Mo₃S₄M] (M = Fe, Co, Ni) Cubes

We have previously shown that cyclopentadienyl (Cp[R])-supported [Mo₃S₄] platforms capture and stabilize halides of hetero-metals (M) under reducing conditions to give [Mo₃S₄M] cubes. Here we report Co and Ni variants with Cp[XL] ligands (Cp[XL] = C₅Me₄SiEt₃) and CO binding to the [Mo₃S₄M] clusters (M = Fe, Co, Ni). Properties of the isolated CO-bound [Mo₃S₄M] cubes were investigated by X-ray diffraction, IR, and electrochemical analyses. Density functional theory (DFT) calculations were performed for the isolated CO-bound clusters to evaluate M-CO interactions. These analyses constitute foundations to develop bio-mimetic molecular catalysts for the direct conversion of CO and/or CO₂ into hydrocarbons, which can contribute to the reduction of carbon emissions

Relationships among depolarizations in scattering of polarized protons from 3He at intermediate energies

We derive relation formulas for proton depolarizations in proton-3He (p-3He) elastic scattering in a form that makes it easy to identify contributions of spin-dependent interactions. The formulas explain approximate relations found in the depolarizations measured at Ep=800 MeV when the magnitudes of scattering amplitudes due to p-3He spin?spin and tensor interactions are small. This nature of the interactions is investigated from the viewpoint of folding models. It is shown that the spin?spin and tensor interactions are significantly diminished owing to characteristics of nucleon densities of 3He, which are calculated from a solution of the Faddeev equation. A folding model calculation with the densities and a simple nuclear potential shows that the p-3He spin?spin interaction is much weaker than the spin-independent central interaction

Polarization phenomena in hyperon-nucleon scattering

We investigate polarization observables in hyperon-nucleon scattering by decomposing scattering amplitudes into spin-space tensors, where each component describes scattering by corresponding spin-dependent interactions, so that contributions of the interactions in the observables are individually identified. In this way, for elastic scattering we find some linear combinations of the observables sensitive to particular spin-dependent interactions such as symmetric spin-orbit (LS) interactions and antisymmetric LS ones. These will be useful to criticize theoretical predictions of the interactions when the relevant observables are measured. We treat vector analyzing powers, depolarizations, and coefficients of polarization transfers and spin correlations, a part of which is numerically examined in +p scattering as an example. Total cross sections are studied for polarized beams and targets as well as for unpolarized ones to investigate spin dependence of imaginary parts of forward scattering amplitudes

Reaction mechanism and characteristics of T_{20} in d + ^3He backward elastic scattering at intermediate energies

For backward elastic scattering of deuterons by ^3He, cross sections \sigma and tensor analyzing power T_{20} are measured at E_d=140-270 MeV. The data are analyzed by the PWIA and by the general formula which includes virtual excitations of other channels, with the assumption of the proton transfer from ^3He to the deuteron. Using ^3He wave functions calculated by the Faddeev equation, the PWIA describes global features of the experimental data, while the virtual excitation effects are important for quantitative fits to the T_{20} data. Theoretical predictions on T_{20}, K_y^y (polarization transfer coefficient) and C_{yy} (spin correlation coefficient) are provided up to GeV energies.Comment: REVTEX+epsfig, 17 pages including 6 eps figs, to be published in Phys. Rev.