Distribution of carbonate in surface sediments of the Pacific Ocean

The distribution of carbonate on the floor of the Pacific has been remapped on the basis of 1313 points from 80 references stored in the World Ocean Sediment Data Bank of Scripps Institution of Oceanography. Percent distribution maps and carbonate versus depth diagrams generally agree with previously published information and reflect the major controlling factors of carbonate sedimentation (depth, hydrography, fertility, and sedimentary processes). While carbonate distributions are of limited use in attempting to construct dissolution profiles, major trends are identifiable. In particular, the degree of lowering of the equatorial calcite compensation depth (CCD) together with an estimate of the differences in supply rates between the equator and the subtropical gyre can be used to estimate dissolution rate increase below the lysocline. There is considerable variation in the sharpness of the ‘CCD transition’ a concept defined here. This variation is thought to reflect both geographic differences in dissolution rate gradients and redeposition processes (carbonate, deep-sea sediments, calcite, and compensation depth)

Chiral SU(3) Dynamics with Coupled Channels: Inclusion of P-Wave Multipoles

We extend our recent non-perturbative chiral SU(3) coupled channel approach to pion- and photon-induced $\eta$- and $K$-meson production off protons by including all strong and electromagnetic p-wave multipoles. We identify the p-wave amplitudes of the next-to-leading order SU(3) chiral meson-baryon Lagrangian with a coupled channel potential which is iterated to infinite orders in a separable Lippmann-Schwinger equation. Our approach to $\eta$- and $K$-photoproduction introduces no additional free parameters. By adjusting a few finite range parameters and the unknown parameters in the Lagrangian, we are able to simultaneously describe a very large amount of low-energy data. These include the total and differential cross sections of the $\pi$-induced reactions $\pi^- p \to \eta n, K^0 \Lambda, K^0 \Sigma^0, K^+ \Sigma^-$ and $\pi^+ p \to K^+ \Sigma^+$ as well as those of photoproduction $\gamma p \to \eta p, K^+\Lambda, K^+ \Sigma^0, K^0 \Sigma^+$. The polarization observables measured in $\eta$- and $K$-photoproduction are particularly sensitive to interference terms between the s- and p-wave multipoles. The total cross section data are remarkably well reproduced in all channels. There remain, however, some open questions concerning details of angular distributions and polarization observables.Comment: 20 pages, 5 figures, accepted for publication in Nucl. Phys.

Effects of the higher partial waves and relativistic terms on the accuracy of the calculation of the hypertriton electroproduction

We have investigated the accuracies of calculations made by omitting the higher partial waves of nuclear wave functions and the elementary relativistic terms in the hypertriton electroproduction. We found that an accurate calculation would still be obtained if we used at least three lowest partial waves with isospin T = 0. Furthermore, we found that the omission of the relativistic terms in the elementary process amplitude could lead to a large deviation from the full calculation. We also present the cpu-times required to calculate the cross sections. For future consideration the use of these lowest partial waves is suggested, since the calculated cross section deviates only about 0.17 nb/sr (approximately 4%), at most, from the full calculation, whereas the cpu-time is reduced by a factor of 60. Comparison of our result with the available experimental data supports these findings.Comment: 12 pages, 4 figures, submitted to Nucl. Phys.

An Isobaric Model for Kaon photoproduction

The kaon photoproduction is analyzed up to $E_\gamma^{\rm Lab}$=2.0 GeV by using an isobaric model based on effective Lagrangians and by taking a cross symmetry into account. Both {\it pseudovector} and {\it pseudoscalar} couplings for kaon-baryon-baryon (baryon spin=1/2) interactions are considered with form factors. A vector meson($K^*(890)$), an axial vector meson($K_1(1270)$), nucleon resonances($J\le5/2$), and hyperon resonances($J\le3/2$) are treated as participating particles. By determining unknown coupling constants through a systematic fitting of the differential cross section, the total cross section, the single polarization observable, and the radiative kaon capture branching ratio to their experimental data, we find out a simple model which reproduces all the experimental data well.Comment: 48 pages, 7 figure

Sedimentary Evolution of the Japan Fore-Arc Region off Northern Honshu, Legs 56 and 57, Deep Sea Drilling Project

The evolution of Neogene and Quaternary sedimentation in the fore-arc region off northern Honshu is evaluated using multichannel and single-channel seismic records in conjunction with the drill holes of the Japan Trench Transect (DSDP/IPOD Legs 56-57). The outer forearc region, which consisted of older sedimentary rocks and some calc-alkaline volcanic rocks, was subaerially exposed and eroded during the Paleogene and part of the Neogene. The deep sea terrace (fore-arc basin) region subsided below sea level in the early Miocene; most rapid subsidence occurred during the early to middle Miocene. Submergence progressed seaward so that the last vestige of the Oyashio landmass, which is now under the upper trench slope, was below sea level in the latest Miocene. Sediment sources to the outer fore-arc basin changed progressively from lithic, predominantly nonvolcanic material derived from the uplifted landmass during the late Paleogene-early Neogene to volcanic, arc-derived sediment rich in volcanic glass, Plagioclase, and volcanic lithic fragments. The volcaniclastic sediment was probably derived both from Honshu to the west and Hokkaido to the northwest. In response to subsidence the sedimentary depocenters in the fore-arc basin migrated generally seaward through time; the greatest relative seaward migration occurred between the late Miocene and Pliocene. Thick sediment sequences accumulated in slope basins on the trench inner slope. Sediment from the arc moved seaward to spill over the slope via large channels. An abrupt change in morphology and patterns of sedimentation apparently took place in the late Pliocene, coincident with a peak in explosive volcanism recorded in the form of ash layers and increased glass contents in sediment. The deep sea terrace was uplifted several hundreds of meters and a major channel crossing the fore-arc region was tilted landward and filled. At about the same time the midslope terrace basin was created and began rapidly accumulating sediment. The older basins, lower on the trench inner slope, were destroyed, possibly by steep seaward tilting, or filled. Large slump masses were sloughed-off downslope to the trench. Little sediment now accumulates on the trench inner slope in the vicinity of the sites, and older strata crop out on the slope. The locus of deposition has shifted northward off Hokkaido where a large channel feeds sediment to the slope. Large slump masses now fill the trench and are being accreted, creating a "toe" to the slope in this region. The evolution of the fore-arc region off northern Honshu has not been steady state. Tectonic accretion has been discontinuous, and tectonic erosion of the continental margin edge may have occurred periodically. Slope basins have been both created and abruptly destroyed at different points on the trench inner slope. There appears to be little possibility of distinguishing most sediment "scraped off" the oceanic plate from hemipelagic sediment deposited in the fore-arc region of Japan

A Spectator-Quark-Model for the Photoproduction of Kaons

A simple model for the photoproduction of kaons off protons with a lambda hyperon in the final state is presented. In a quark model, the interaction is modelled by the pair-creation of the (anti-) strange quarks in the final state which recombine with the three quarks of the proton to form the lambda and kaon. The calculated scattering cross sections for photon energies up to E_\gamma = 1.9 \; \mbox{GeV} are compared to experiment. The pair-creation process is found to have a significant contribution to the total cross section.Comment: 16 pages, LaTex, 10 figures included; packed with 'uufiles' utilit

gKNΛg_{K N \Lambda} and gKNΣg_{K N \Sigma} from QCD sum rules

$g_{K N \Lambda}$ and $g_{K N \Sigma}$ are calculated using a QCD sum rule motivated method used by Reinders, Rubinstein and Yazaki to extract Hadron couplings to goldstone bosons. The SU(3) symmetry breaking effects are taken into account by including the contributions from the strange quark mass and assuming different values for the strange and the up down quark condensates. We find $g_{K N \Lambda}/\sqrt{4 \pi} = - 1.96$ and $g_{K N \Sigma}/\sqrt{4 \pi} = 0.33$Comment: 14 pages (REVTeX) and 2 PS figure

Gerasimov-Drell-Hearn Sum Rule and the Discrepancy between the New CLAS and SAPHIR Data

Contribution of the K^+\Lambda channel to the Gerasimov-Drell-Hearn (GDH) sum rule has been calculated by using the models that fit the recent SAPHIR or CLAS differential cross section data. It is shown that the two data sets yield quite different contributions. Contribution of this channel to the forward spin polarizability of the proton has been also calculated. It is also shown that the inclusion of the recent CLAS C_x and C_z data in the fitting data base does not significantly change the result of the present calculation. Results of the fit, however, reveal the role of the S_{11}(1650), P_{11}(1710), P_{13}(1720), and P_{13}(1900) resonances for the description of the C_x and C_z data. A brief discussion on the importance of these resonances is given. Measurements of the polarized total cross section \sigma_{TT'} by the CLAS, LEPS, and MAMI collaborations are expected to verify this finding.Comment: 15 pages, 8 figure

Charm meson production from meson-nucleon scattering

Using an effective hadronic Lagrangian with physical hadron masses and coupling constants determined either empirically or from SU(4) flavor symmetry, we study the production cross sections of charm mesons from pion and rho meson interactions with nucleons. With a cutoff parameter of 1 GeV at interaction vertices as usually used in studying the cross sections for $J/\psi$ absorption and charm meson scattering by hadrons, we find that the cross sections for charm meson production have values of a few tenth of mb and are dominated by the s channel nucleon pole diagram. Relevance of these reactions to charm meson production in relativistic heavy ion collisions is discussed.Comment: 8 pages, 4 figures, slight revision and references adde

Quasi-elastic knockout of pions and kaons from nucleons by high-energy electrons and quark microscopy of "soft" meson degrees of freedom in the nucleon

Electro-production of pions and kaons at the kinematics of quasi-elastic knockout (which is well known in the physics of atomic nucleus and corresponds to the $t$-pole diagram) is proposed for obtaining their momentum distribution (MD) in various channels of virtual decay $N \to B+\pi$, $B=N$, $\Delta$, $N^*$, $N^{**}$, and $N \to Y+K$, $Y=\Lambda$, $\Sigma$. It is a powerful tool for investigation of a quark microscopic picture of the meson cloud in the nucleon. A model of scalar $q \bar{q}$ ($^3P_0$) fluctuation in the non-trivial QCD vacuum is used to calculate pion and kaon momentum distributions (MD) in these channels.Comment: 31 pages, 11 figures, submitted to Nucl.Phys.