Meson Dynamics and the resulting "3-Nucleon-Force" diagrams: Results from a simplified test case

A simplified 1D (one-dimensional) model for a generalized 3N system is considered, as a testing ground for the explicit treatment of the meson dynamics in this system. We focus attention on the irreducible diagrams generated by the pion dynamics in the 3N system, and in particular to a new type of three-nucleon force discussed recently in the literature, and generated by the one-pion-exchange mechanism in presence of a nucleon-nucleon correlation. It is found that these new terms in the simplified model have an approximately 30% effect compared to the standard three-nucleon force terms in a `Triton' binding energy calculation. It is suggested that this effect should also not be ignored in realistic calculations.Comment: 4 pages, Contribution to "Mesons and Light Nuclei 2001", Prague 2-6, 200

Antenna pattern of DUAL detectors of gravitational waves and its exploitation in a network of advanced interferometers

We investigate the directional sensitivity to plane gravitational waves (GWs) of DUAL detectors of cylindrical shape. Calculations make use of the finite element method to simulate the responses to the GW Riemann tensor of a single-mass DUAL (SMD) and of a tapered cylinder (TC) in their wide sensitivity bandwidth. We show that one SMD or a pair of TCs is able to cover both GW polarization amplitudes from almost all incoming directions. We discuss the achievable enhancement in tackling the inverse problem for high frequency [~(2–5) kHz] GWs by adding a TC detector to the future advanced LIGO–VIRGO network

Spin observables for pion production from pd collisions

We have calculated the proton analyzing power A_{y0} of the pion-production reaction from pd collisions for one energy close to threshold and for another in the region of the $\Delta$-resonance. A fair reproduction of the experimental data could be obtained in both cases with a model which includes isoscalar and isovector $\pi N$ rescatterings in s waves, as well as the p-wave rescattering mechanisms mediated by the $\pi NN$ and $\pi N \Delta$ vertices. For the analyzing power at threshold we found that the initial-state interaction (ISI) is also quite important.Comment: Talk at XVIth International Conference on Few-Body Problems in Physics, Taipei, Taiwan, March 6-10 2000. 3 pages, latex, 2 figures -- To appear in Nuclear Physics A -- fleqn.sty and espcrc1.sty require

Non-localities in nucleon-nucleus potentials

Two causes of non-locality inherent in nucleon-nucleus scattering are considered. They are the results of two-nucleon antisymmetry of the projectile with each nucleon in the nucleus and the dynamic polarization potential representation of channel coupling. For energies $\sim 40 - 300$ MeV, a g-folding model of the optical potential is used to show the influence of the knock-out process that is a result of the two-nucleon antisymmetry. To explore the dynamic polarization potential caused by channel coupling, a multichannel algebraic scattering model has been used for low-energy scattering.Comment: 12 pages, 11 figures, submitted to EPJ

Three-nucleon portrait with pion

We report on recent results obtained by the above collaboration on the collision processes involving three nucleons, where we pay particular attention on the dynamical role of the pion. After discussing the case at intermediate energies, where real pions can be produced and detected, we have considered the case at lower energies, where the pions being exchanged are virtual. The study has revealed the presence of some new pion-exchange mechanisms, which leads to a new three-nucleon force of tensor structure. Recently, the effect of this tensor three-nucleon force to the spin observables for neutron-deuteron scattering at low energy has been analyzed, and will be briefly reviewed.Comment: To appear in the Proceedings of 8th Convegno su Problemi di Fisica Nucleare Teorica (Cortona 2000), Cortona, Italy, 18-21 Oct 2000. 8 pages, uses ws-p8-50x6-00.cl