RSS FewBody Systems

Positronium Negative Ion Embedded in Nonideal Classical Plasmas: Doubly Excited Singlet S States
Abstract
The effects of the nonideality (NI) of the classical plasmas on the doubly excited singlet S states in the positronium negative ion (Ps \(^\) ) are investigated. The organised effect of the plasma is taken care of by means of a pseudopotential which is characterised by the Debye length D and the nonideality parameter \(\gamma \) . Using an extensive wavefunction within the framework of the stabilization method, it has been possible to identify four doubly excited states (DES) in Ps \(^\) . The convergence of the energy and the width of those states are corroborated by increasing the number of terms in the wavefunction. Our present calculation for the plasmafree case reproduces the established results. An inclusive study is made to quantify and qualify the changes experienced by the energies and the widths of those states due to the influence of the NI over a wide range. It is observed that the energy of each DES increases and the width of each DES diminishes due to the effect of the increasing NI of the plasma.

Experiments of FewNucleon Scattering to Explore ThreeNucleon Forces
Abstract
Fewnucleon scattering offers a good opportunities to study dynamical aspects of threenucleon forces, that are momentum, spin and isospin dependent. In the paper, the experimental results of deuteronproton elastic scattering at \(\sim ~\mathrm 100\) MeV/nucleon obtained in the course of the study are presented. The experimental study of fewnucleon scattering has been recently extended to the proton \(^3 \textrm{He}\) scattering with the aim of approaching the isospin \(T=3/2\) channel in threenucleon forces. The data are in comparison with the rigorous numerical calculations based on stateoftheart nuclear potentials with threenucleon forces.

Impact of the $$\hbox {N}^4\hbox {LO}$$ ShortRange ThreeNucleon Force Components on the NucleonDeuteron Spin Correlation Coefficients
Abstract
The spin correlation coefficients in the neutrondeuteron elastic scattering process at incoming neutron laboratory energies \(\hbox {E}=10\) , 135, 190, and 250 MeV are determined by solving the momentum space threenucleon (3N) Faddeev equations. The chiral twonucleon (2N) interaction with momentumspace semilocal (SMS) regularization up to the fifth order of chiral expansion ( \(\hbox {N}^4\hbox {LO}\) ), supplemented by the Fwaves terms from the sixth order ( \(\hbox {N}^5\hbox {LO}\) ), is used. Additionally, the consistent 3N force (3NF) at the third order of chiral expansion, supplemented by the shortrange contributions from \(\hbox {N}^4\hbox {LO}\) is applied. As a results, we give predictions for the complete set of spin correlation coefficients \(C_{\alpha ,\beta }\) . We find that the effect of the investigated threenucleon \(\hbox {N}^4\hbox {LO}\) components amounts up to several dozen percent, depending on reaction energy, scattering angle and type of spin correlation coefficient itself. Our results can serve as a guide for future measurements of the spin correlation coefficients.

A New Quantization of Hadron System and UltraLow Energy Nuclear Fusion
Abstract
A new quantization is proposed for an energydependent particle exchange potential. The quantum number corresponds not only to the branch point of the potential cut, but also to the index of a longrange hadron potential. By using the longrange potential, an ultralow energy nuclear (ULEN) reaction is investigated. It was found that a threebody Cs + H + H plasma in a Pd \(_{12}\) cage could be excited to \(1.36\times 10^{4}\) eV \(\sim 300\) eV by an electric current where the longrange potential gives one or two order larger reaction probability than the others. A ULEN reaction was compared with the thermonuclear fusion by using wellknown critical fusion constant defined by \(C_{high/low}\) = (a duration time) \(\times \) (a plasma density) \(\times \) (a temperature). We found that \(C_{low}\) is almost the same as \(C_{high}\) or more. We concluded that the ULEN synthesis could occur with a highpressure hydrogen circumstance and a highdensity CsH \(_2\) Pd \(_{12}\) cluster.

Puzzles of Exotic Decay Processes
Abstract
The growing interest in the physics of unstable nuclei, along with their manifestations in laboratory experiments and astrophysical observations, highlights the existence of features in decay processes within complex quantum systems that are not yet fully understood. This paper considers examples of such phenomena, including twostep decay processes, resonance effects, threshold peculiarities, and the interactions between bound and continuum states, as well as the related dynamics.