Pion Effect of Nuclear Matter in a Chiral Sigma Model

We develop a new framework for the study of the nuclear matter based on the linear sigma model.We introduce a completely new viewpoint on the treatment of the nuclear matter with the inclusion of the pion.We extend the relativistic chiral mean field model by using the similar method in the tensor optimized shell model.We also regulate the pion-nucleon interaction by considering the form-factor and short range repulsion effects.We obtain the equation of state of nuclear matter and study the importance of the pion effect.     

Tensor optimized antisymmetrized molecular dynamics for relativistic nuclear matter

We apply a newly developed many-body theory, tensor optimized antisymmetrized molecular dynamics (TOAMD), to nuclear matter using a relativistic bare nucleon-nucleon interaction in the relativistic framework. It becomes evident that the tensor interaction plays an important role in nuclear many-body system due to the role of the pion in a strongly interacting system. We take the relativistic nuclear matter (RNM) wave function as a basic state and add tensor and short-range correlation operators in the form of pion and omega-meson correlation functions acting on the RNM wave function using the concept of TOAMD. We use the Monte Carlo (Metropolis) method based on the Gaussian integration and the second quantization method for antisymmetrization to calculate all the matrix elements of the many-body Hamiltonian. We write the whole formula of the TOAMD method for numerical calculations of the nuclear binding and saturation properties of nuclear matter using one-boson exchange potential.     

Evolution of nuclear spectra with nuclear forces

We first define a series of NN interaction models ranging from very simple to fully realistic. We then present Green's function Monte Carlo calculations of light nuclei to show how nuclear spectra evolve as the nuclear forces are made increasingly sophisticated. We find that the absence of stable five- and eight-body nuclei depends crucially on the spin, isospin, and tensor components of the nuclear force.     

Memory effects in nuclear Fermi-liquid

The kinetic theory is applied to the nuclear Fermi liquid. The nuclear collective dynamics is treated in terms of the observable variables: particle density, current density, pressure etc. The influence of Fermi-surface distortion, relaxation processes and memory effects on the nuclear dynamics is studied. We show that the presence of the dynamic Fermi-surface distortion gives rise to some important consequences in the nuclear dynamics which are absent in classical liquids. We discuss the nuclear small amplitude excitations, the spinodal instability, the nuclear fission and the bubble instability in heated Fermi-liquid in presence of the memory effects.     

Nuclear and neutron star radii

We investigate the correlation between nuclear neutron radii and the radius of neutron stars. We use a well-established hadronic SU(3) model based on chiral symmetry that naturally includes nonlinear vector meson and scalar meson–vector meson couplings. The relative strengths of the couplings modify the nuclear isospin-dependent interactions. We study the dependence of nuclear and neutron star radii on the coupling strengths. The relevance of the results for parity-violating electron–nucleus scattering is discussed.     

Extremal decomposition of Wightman functions and of states on nuclear *-algebras by Choquet theory

We give a short proof for the decomposability of states on nuclear *-algebras into extremal states by using the integral decompositions of Choquet and the nuclear spectral theorem, recovering a recent result by Borchers and Yngvason. The decomposition of Wightman fields into irreducible fields is a special case of this. We also indicate a quick solution of the moment problem on nuclear spaces.     

Dynamics of quantum dot nuclear spin polarization controlled by a single electron

We present measurements of the buildup and decay of nuclear spin polarization in a single semiconductor quantum dot. Our experiment shows that we polarize the nuclei in a few milliseconds, while their decay dynamics depends drastically on external parameters. We show that a single electron can very efficiently depolarize nuclear spins in milliseconds whereas in the absence of the electron the nuclear spin lifetime is on the scale of seconds. This lifetime is further enhanced by 1-2 orders of magnitude by quenching the nonsecular nuclear dipole-dipole interactions with a magnetic field of 1 mT.     

Update on nuclear structure effects in light muonic atoms

We present calculations of the nuclear structure corrections to the Lamb shift in light muonic atoms, using state-of-the-art nuclear potentials. We outline updated results on finite nucleon size contributions.     

Correlation and finite interaction-range effects in high energy electron inclusive scattering

We calculate cross sections of high energy electron inclusive scattering off nuclear matter in a new and consistent formulation based on the Glauber approximation. It allows us to examine the details of the nucleon-nucleon interaction in the final-state interaction and the nuclear wave function. We point out the importance of the finite-range effect and of the nuclear short-range correlations.     

Nuclear effects in the F3 structure function for finite and asymptotic Q

We study nuclear effects in the structure function F₃ which describes the parity violating part of the charged-current neuitrino nucleon deep inelastic scattering. Starting from a covariant approach we derive a factorized expression for the nuclear structure function in terms of the nuclear spectral function and off-shell nucleon structure functions valid for arbitrary momentum transfer Q and in the limit of weak nuclear binding, i.e. when a nucleus can be treated as a non-relativistic system. We develop a systematic expansion of nuclear structure functions in terms of a Q⁻² series caused by nuclear effects (“nuclear twist” series). Basing ourselves on this expansion we calculate nuclear corrections to the Gross-Llewellyn-Smith sum rule as well as to higher moments of F₃. We show that corrections to the GLS sum rule due to nuclear effects cancel out in the Bjorken limit and calculate the corresponding Q⁻² correction. Special attention is paid to the discussion of the off-shell effects in the structure functions. A sizable impact of these effects both on the Q² and x dependence of nuclear structure functions is found.     

Dynamic Nuclear Polarization in III–V Semiconductors

We report on electron spin resonance, nuclear magnetic resonance and Overhauser shift experiments on two of the most commonly used III–V semiconductors, GaAs and InP. Localized electron centers in these semiconductors have extended wavefunctions and exhibit strong electron–nuclear hyperfine coupling with the nuclei in their vicinity. These interactions not only play a critical role in electron and nuclear spin relaxation mechanisms, but also result in transfer of spin polarization from the electron spin system to the nuclear spin system. This transfer of polarization, known as dynamic nuclear polarization (DNP), may result in an enhancement of the nuclear spin polarization by several orders of magnitude under suitable conditions. We determine the critical range of doping concentration and temperature conducive to DNP effects by studying these semiconductors with varying doping concentration in a wide temperature range. We show that the electron spin system in undoped InP exhibits electric current-induced spin polarization. This is consistent with model predictions in zinc-blende semiconductors with strong spin–orbit effects.     

核物质中内介质等效手征Lagrange量和π介子质量

在核物质中从手征等效Lagrange量得到的π介子有效质量是单值的,并且与π介子场的离壳扩展无关,例如PCAC选择.同位旋对称核物质中的有效π介子质量随增加的核密度有些上升,因此有效类时π介子衰变常数和密度相关的夸克凝聚渐渐下降.另外研究了内介质Gell–Mann–Oakes–Renner关系和其它内介质同一性.最后讨论了同位旋对称、各向同性和均匀的核物质中关于介子传播的等效Lagrange量的几个限制.     

Solid-state quantum computation—a new direction for nanotechnology

We review current proposals for six types of solid-state quantum computers. We discuss the general requirements for solid-state quantum computers and describe proposals which employ superconducting junctions, electron orbitals in quantum dots, electron spin resonance, nuclear spins of impurity atoms, and nuclear spins in a crystal lattice. We also describe our proposed nuclear spin quantum computer based on magnetic resonance force microscopy. Finally, we describe our numerical method for modeling quantum transformations with a large number (up to 1000) of qubits.     

Study of the Binding Energy of Relativistic Nuclear Matter in the Relativistic σ-ω-π Model

A relativistic σ-ω-π model is proposed to calculate the binding energy of relativistic nuclear matter. We put emphasis on the relativistic particle-hole, delta-hole excitation of pion propagator in nuclear matter. The renormalization of the nucleon self-energy in nuclear matter is made for the pseudo-vector πNN and πNΔ couplings by introducing corresponding form factor and by dispersion relation. We find that the density dependence correction to meson-NN coupling constants is very important to saturate the binding energy of nuclear matter. The density dependence correction to πNN and πNΔ coupling constants has the effect of softening the EOS of nuclear matter.     

核物理与核探测、核分析技术的应用

文章概要介绍了随着核物理研究发展起来的辐射和粒子探测的原理、方法和主要技术,举例介绍了相关核物理与核探测、核分析的典型技术及其在高精度测量和医学中的广泛应用,如活化分析技术、穆斯堡尔谱学、核磁共振技术、加速器质谱技术、核医学成像、同步辐射技术、中子散射分析、放射性示踪技术等等.     

Relativistic many-body theory with radioactive ion beams: Surface pion condensation

We critically review the present relativistic mean-field theory from the viewpoint of missing pions. We introduce the interesting experimental data on pionic states taken at RCNP. These data seem to suggest the occurrence of pion condensation in the nuclear surface. Qualitative discussion is made on the consequence of surface pion condensation on Gamow-Teller transitions and spin response functions and others. The radioactive ion beams are the tools of studying the unstable nuclei, which have extended nuclear surfaces. We shall start with radioactive ion beams the nuclear surface science, which includes the surface pion condensation as the important ingredient in addition to spin-orbit splitting and surface pairing. Received: 1 May 2001 / Accepted: 4 December 2001     

New perspectives in the studies of resonance scattering

We consider various possibilities for studies of nuclear structure in resonance reactions induced by radioactive beam. We discuss investigations on both sides of nuclear stability as well as studies of the α-cluster structure of light nuclei applying the reverse geometry thick target method.     

Probing the nuclear symmetry energy with heavy-ion reactions induced by neutron-rich nuclei

Heavy-ion reactions induced by neutron-rich nuclei provide a unique means to investigate the equation of state of isospin-asymmetric nuclear matter, especially the density dependence of the nuclear symmetry energy. In particular, recent analyses of the isospin diffusion data in heavy-ion reactions have already put a stringent constraint on the nuclear symmetry energy around the nuclear matter saturation density. We review this exciting result and discuss its implications on nuclear effective interactions and the neutron skin thickness of heavy nuclei. In addition, we also review the theoretical progress on probing the high density behaviors of the nuclear symmetry energy in heavy-ion reactions induced by high energy radioactive beams.      

Gluon shadowing and charmonium/bottonium production on nuclear targets

We examine the suppression ofJ/ω, ω′ and Ψ production on nuclear targets, as observed for proton and pion beams of energies from 200 to 800 GeV. We find that this suppression leads to a universal scaling curve, which indicates that it is due to nuclear modifications of the gluon density (“shadowing”). A parametrisation of the nuclear effect on the gluon density is extracted from the data and used to obtain quantitative estimates for corresponding effects in high-energy heavyion collisions.     

Methods for investigating nuclear matter under the conditions characteristic of its transition to quark-gluon plasma

We briefly consider the properties of deep inelastic nuclear reactions on dense fluctuations of nuclear matter (fluctons). We discuss the properties of the fluctons, which can be many-quark bags or “drops” of quark-gluon plasma: the characteristic parameters of nuclear matter in a flucton— temperature and density close to the critical values for a phase transition. These values can be reached or exceeded if the flucton-flucton collision events are separated out. The separation method is discussed.