T l e Tilted Axis Cranking theory is applied to tlie rnodel of two pxticles coupled to a triaxial rotor. Cornpariiig with tlie exact quantd solutioris, tlie i~iterpretation and quality of the rnean field approxirriatiori is studied. Conditions are discussed when the axis of rotatiori lies inside or outside of the priricipal planes of tlie triaxial clensity distribution. Tlie plariiw soIiitions represent A I = 1 baids, whereas the aplariar soliitioris rcprcserit pairs of ideritical A I = 1 bands with the sarne parity. Thc two barids differ by the chirality of tlie priricipal axes witli rcspcct to tlie angithr rnonieritiirn vector. Tlie trarisitiori frorn plariar to chiral soliitioris is eviclerit in botli tlie quarital arid the niean field calciilatioris. Its pliysicel origin is discussed.

A new parametrization PC-PK1 for the nuclear covariant energy density functional with nonlinear point-coupling interaction is proposed by fitting to observables of 60 selected spherical nuclei, including the binding energies, charge radii and empirical pairing gaps. The success of PC-PK1 is illustrated in the description for infinite nuclear matter and finite nuclei including the ground-state and low-lying excited states. Particularly, PC-PK1 provides good description for isospin dependence of binding energy along either the isotopic or the isotonic chains, which makes it reliable for application in exotic nuclei. The predictive power of PC-PK1 is also illustrated for the nuclear low-lying excitation states in a five-dimensional collective Hamiltonian in which the parameters are determined by constrained calculations for triaxial shapes.

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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...

By taking into account the surface diffuseness correction for unstable nuclei, the accuracy of the macroscopic-microscopic mass formula is further improved. The rms deviation with respect to essentially all the available mass data falls to 298 keV, crossing the 0.3 MeV accuracy threshold for the first time within the mean-field framework. Considering the surface effect of the symmetry potential which plays an important role in the evolution of the "neutron skin" toward the "neutron halo" of nuclei approaching the neutron drip line, we obtain an optimal value of the symmetry energy coefficient J=30.16 MeV. With an accuracy of 258 keV for all the available neutron separation energies and of 237 keV for the alpha-decay Q-values of super-heavy nuclei, the proposed mass formula is particularly important not only for the reliable description of the r-process of nucleosynthesis but also for the study of the synthesis of super-heavy nuclei.Comment: 2 figures, 2 tables, to appear in Phys. Lett.

A new relativistic Hartree-Fock approach with density-dependent σ, ω, ρ and π meson-nucleon couplings for finite nuclei and nuclear matter is presented. Good description for finite nuclei and nuclear matter is achieved with a number of adjustable parameters comparable to that of the relativistic mean field approach. With the Fock terms, the contribution of the π-meson is included and the description for the nucleon effective mass and its isospin and energy dependence is improved.The relativistic mean field (RMF) theory [1, 2] has received much attention due to its successful description of numerous nuclear phenomena [3,4,5,6,7,8,9]. In its most widely employed versions, i.e., with either self-coupling interactions or density-dependent meson-nucleon couplings, the RMF theory with a limited number of parameters can describe very well a very large amount of data: saturation properties of nuclear matter [10], nuclear binding energies and radii, the isotopic shifts in the Pb-region [11]. It gives a natural description of the nuclear spin-orbit potential [12], and explains the origin of the pseudospin symmetry [13,14] and spin symmetry of the anti-nucleon spectrum [15] as a relativistic symmetry [15,16,17,18]. In spite of these success, there are still a number of questions needed to be answered in the RMF theory: the contributions due to the exchange (Fock) terms and the pseudo-scalar π-meson.There exist attempts to include the exchange terms in the relativistic description of nuclear matter and finite nuclei. The earlier relativistic Hartree-Fock (RHF) method led to underbound nuclei due to the missing of the meson self-interactions [19]. Further developments were made by taking into account approximately the nonlinear self-couplings of the σ-field [20] or by introducing the products of six and eight nucleon spinors in the zero-range limit [21]. Although some improvements were obtained, the RHF method is still not comparable with the RMF theory in the quantitative description of nuclear systems. The relativistic point coupling model has been used to investigate nuclei systems [22] and the

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 − .