New parameter sets for the Lagrangian density in the relativistic mean field (RMF) theory, PK1 with nonlinear σ-and ω-meson self-coupling, PK1R with nonlinear σ-, ω-and ρ-meson self-coupling and PKDD with the density-dependent meson-nucleon coupling, are proposed. They are able to provide an excellent description not only for the properties of nuclear matter but also for the nuclei in and far from the valley of beta-stability. For the first time in the parametrization of the RMF Lagrangian density, the center-of-mass correction is treated by a microscopic way, which is essential to unify the description of nuclei from light to heavy regions with one effective interaction. PACS numbers: 21.60.-n, 21.30.Fe, 21.60.Jz, 21.10.Dr I. INTRODUCTIONIn the past decade, the development of unstable nuclear beams [1,2] has extended our knowledge of nuclear physics from the stable nuclei and those nearby to the unstable nuclei far from the stability line. Intense research in this area shows that there exist lots of unexpected phenomena: strange nuclear structure like neutron halo (skin) and proton halo (skin) [3-10], soft excitation modes [11,12], the enhancement of fusion cross sections induced by the extended matter distributions [13,14] etc.. With further developments, many other new features will be found. It also becomes very important to find a reliable theory and improve the reliability for predicting the properties of even more exotic nuclei out to the proton and neutron drip lines.Relativistic mean field (RMF) [15,16] theory has received wide attention because of its successful description of many nuclear phenomena during the past years. With a very limited number of parameters, RMF theory is able to give a satisfactory description for the ground state properties of spherical [17] and deformed nuclei [18] at and away from the stability line. The recent reviews on RMF theory can be seen in [16][17][18]. In the simplest version of RMF theory, the mesons do not interact among themselves, which results in a too large incompressibility for nuclear matter. Boguta and Bodmer [19] therefore proposed to include a nonlinear self-coupling of the σ-field, a concept which has been used in almost all the recent applications. The meson self-coupling introduces a new density dependence into the Lagrangian and consequently, the nuclear matter incompressibility can be lowered to reasonable values. As an implement, in 1994 the nonlinear self-coupling of the ω-field is introduced by Sugahara and Toki [20]. In this paper we will introduce the nonlinear self-coupling for the ρ-field. Recently RMF theory with density-dependent (DD) meson-nucleon couplings [21][22][23][24] was developed by various authors.Till now the two versions (the nonlinear self-coupling of meson fields and the DD meson-nucleon couplings) of RMF theory have been successfully applied to describe the nuclear properties, including binding energies, nuclear matter distribution, single-particle spectra, magnetic moments, collective excited states, dipole sum rule, shell effec...

The ground state properties including radii, density distribution and one neutron separation energy for C, N, O and F isotopes up to the neutron drip line are systematically studied by the fully self-consistent microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) theory. With the proton density distribution thus obtained, the charge-changing cross sections for C, N, O and F isotopes are calculated using the Glauber model. Good agreement with the data has been achieved. The charge changing cross sections change only slightly with the neutron number except for proton-rich nuclei. Similar trends of variations of proton radii and of charge changing cross sections for each isotope chain is observed which implies that the proton density plays * e-mail: mengj@pku.edu.cn 1 important role in determining the charge-changing cross sections.PACS numbers: 21.10. Gv, 24.10.Cn, 25.45.De Key words: Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, charge-changing cross section, neutron-rich light nuclei, exotic nuclei Typeset using REVT E X 2 Recent progresses in the accelerator and detection techniques all around the world have made it possible to produce and study the nuclei far away from the stability line -so called "EXOTIC NUCLEI". Based on the measurement of interaction cross section with radioactive beams at relativistic energy, novel and entirely unexpected features has appeared: e.g., the neutron halo and skin as the rapid increase in the measured interaction cross-sections in the neutron-rich light nuclei [1,2].Systematic investigation of interaction cross sections for an isotope chain or an isotone chain can provide a good opportunity to study the density distributions over a wide range of isospin [3,4]. However the contribution from proton and neutron are coupled in the measurement of interaction cross section. To draw conclusion on the differences in proton and neutron density distributions definitely, a combined analysis of the interaction cross section and other experiment on either proton or neutron alone are necessary.The charge-changing cross section which is the cross section for all processes which result in a change of the atomic number for the projectile can provide good opportunity for this purpose. In Ref.[5], the total charge-changing cross section σ cc for the light stable and neutron-rich nuclei at relativistic energy on a carbon target were measured. We will study σ cc theoretically by using the fully self-consistent and microscopic relativistic continuum Hartree-Bogoliubov (RCHB) theory and the Glauber Model in the present letter.The RCHB theory [6][7][8], which is an extension of the relativistic mean field (RMF) [9][10][11] and the Bogoliubov transformation in the coordinate representation, can describe satisfactorily the ground state properties for nuclei both near and far from the β-stability line and from light to heavy or super heavy elements, as well as for the understanding of pseudo-spin symmetry in finite nuclei [12][13][14][15]. A remarkable success of the RCHB t...

Experimental data on Coulomb breakup and neutron removal indicate that 31 Ne is one of the heaviest halo nuclei discovered so far. The possible ground state of 31 Ne is either 3/2 − coming from p-wave halo or 1/2 + from s-wave halo. In this work, we develop a treatable model to include deformed wave functions and a dynamical knockout formalism which includes the dependence on the nuclear orientation to study the neutron removal from 31 Ne projectiles at energies around E ≈ 200 MeV/nucleon. A detailed account of the effects of deformation on cross sections and longitudinal momentum distributions is made. Our numerical analysis indicates a preference for the 31 Ne ground state with spin parity 3/2 − .

We discuss spin and pseudo-spin symmetry in the spectrum of single nucleons and single antinucleons in a nucleus. As an example we use relativistic mean field theory to investigate single anti-nucleon spectra. We find a very well developed spin symmetry in single anti-neutron and single anti-proton spectra. The dominant components of the wave functions of the spin doublet are almost identical. This spin symmetry in anti-particle spectra and the pseudo-spin symmetry in particle spectra have the same origin. However it turns out that the spin symmetry in anti-nucleon spectra is much better developed than the pseudo-spin symmetry in normal nuclear single particle spectra. 21.10.Hw, 21.10.Pc, 21.60.Jz Symmetries in single particle spectra of atomic nuclei have been discussed extensively in the literature, as the violation of spin-symmetry by the spin-orbit term and approximate pseudo-spin symmetry in nuclear single particle spectra: atomic nuclei are characterized by a very large spin-orbit splitting, i.e. pairs of single particle states with opposite spin (j = l ± 1 2 ) have very different energies. This fact allowed the understanding of magic numbers in nuclei and forms the basis of nuclear shell structure. More than thirty years ago [1, 2] pseudo-spin quantum numbers have been introduced byl = l ± 1 and j = j for j = l ± 1 2 and it has been observed that the splitting between pseudo-spin doublets in nuclear single particle spectra is by an order of magnitude smaller than the normal spin-orbit splitting.After the observation that relativistic mean field models yield spectra with nearly degenerate pseudo spin-orbit partners [3], Ginocchio showed clearly that the origin of pseudo-spin symmetry in nuclei is given by a relativistic symmetry in the Dirac Hamiltonian ([4, 5] and references given therein). He found that pseudo-spin symmetry becomes exact in the limiting case, where the strong scalar and vector potentials have the same size but opposite sign. However, this condition is never fulfilled exactly in real nuclei, because in this limit the average nuclear potential vanishes and nuclei are no longer bound. It has been found that the quality of pseudo-spin symmetry is related to the competition between the centrifugal barrier and the pseudo-spin orbital potential [6].In relativistic investigations a Dirac Hamiltonian is used. In its spectrum one finds single particle levels with positive energies as well as those with negative energies. The latter are interpreted as anti-particles under charge conjugation. This has lead to much efforts to explore configurations with anti-particles and their interaction with nuclei. The possibility of producing a new kind of nuclear system by putting one or more anti-baryons inside ordinary nuclei has recently gained renewed interest [7]. For future studies of anti-particles in nuclei it is therefore of great importance to investigate the symmetries of such configurations.In a relativistic description nuclei are characterized by two strong potentials, an attactive scalar fiel...

The Woods-Saxon basis has been suggested to replace the widely used harmonic oscillator basis for solving the relativistic mean field (RMF) theory in order to generalize it to study exotic nuclei. As examples, relativistic Hartree theory is solved for spherical nuclei in a Woods-Saxon basis obtained by solving either the Schrödinger equation or the Dirac equation (labelled as SRHSWS and SRHDWS, respectively and SRHWS for both). In SRHDWS, the negative levels in the Dirac Sea must be properly included. The basis in SRHDWS could be smaller than that in SRHSWS which will simplify the deformed problem. The results from SRHWS are compared in detail with those from solving the spherical relativistic Hartree theory in the harmonic oscillator basis (SRHHO) and those in the coordinate space (SRHR). All of these approaches give identical nuclear properties such as total binding energies and root mean square radii for stable nuclei. For exotic nuclei, e.g., 72 Ca, SRHWS satisfactorily reproduces the neutron density distribution from SRHR, while SRHHO fails. It is shown that the Woods-Saxon basis can be extended to more complicated situations for exotic nuclei where both deformation and pairing have to be taken into account.

Symmetry plays a fundamental role in physics. The quasi-degeneracy between single-particle orbitals $(n, l, j = l + 1/2)$ and $(n-1, l + 2, j = l + 3/2)$ indicates a hidden symmetry in atomic nuclei, the so-called pseudospin symmetry (PSS). Since the introduction of the concept of PSS in atomic nuclei, there have been comprehensive efforts to understand its origin. Both splittings of spin doublets and pseudospin doublets play critical roles in the evolution of magic numbers in exotic nuclei discovered by modern spectroscopic studies with radioactive ion beam facilities. Since the PSS was recognized as a relativistic symmetry in 1990s, many special features, including the spin symmetry (SS) for anti-nucleon, and many new concepts have been introduced. In the present Review, we focus on the recent progress on the PSS and SS in various systems and potentials, including extensions of the PSS study from stable to exotic nuclei, from non-confining to confining potentials, from local to non-local potentials, from central to tensor potentials, from bound to resonant states, from nucleon to anti-nucleon spectra, from nucleon to hyperon spectra, and from spherical to deformed nuclei. Open issues in this field are also discussed in detail, including the perturbative nature, the supersymmetric representation with similarity renormalization group, and the puzzle of intruder states.Comment: Review Article, 242 pages, 58 figures, 10 table

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A deformed relativistic Hartree Bogoliubov (RHB) theory in continuum is developed aiming at a proper description of exotic nuclei, particularly those with a large spatial extension. In order to give an adequate consideration of both the contribution of the continuum and the large spatial distribution in exotic nuclei, the deformed RHB equations are solved in a Woods-Saxon (WS) basis in which the radial wave functions have a proper asymptotic behavior at large distance from the nuclear center. This is crucial for the proper description of a possible halo. The formalism of deformed RHB theory in continuum is presented. A stable nucleus, 20 Mg and a weakly-bound nucleus, 42 Mg, are taken as examples to present numerical details and to carry out necessary numerical checks. In addition, the ground state properties of even-even magnesium isotopes are investigated. The generic conditions of the formation of a halo in weakly bound deformed systems and the shape of the halo in deformed nuclei are discussed. We show that the existence and the deformation of a possible neutron halo depend essentially on the quantum numbers of the main components of the single particle orbitals in the vicinity of the Fermi surface.