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...

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

A new effective interaction PKA1 with ρ-tensor couplings for the density-dependent relativistic Hartree-Fock (DDRHF) theory is presented. It is obtained by fitting selected empirical ground state and shell structure properties. It provides satisfactory descriptions of nuclear matter and the ground state properties of finite nuclei at the same quantitative level as recent DDRHF and RMF models. Significant improvement on the single-particle spectra is also found due to the inclusion of ρ-tensor couplings. As a result, PKA1 cures a common disease of the existing DDRHF and RMF Lagrangians, namely the artificial shells at 58 and 92, and recovers the realistic sub-shell closure at 64. Moreover, the proper spin-orbit splittings and well-conserved pseudo-spin symmetry are obtained with the new effective interaction PKA1. Due to the extra binding introduced by the ρ-tensor correlations, the balance between the nuclear attractions and the repulsions is changed and this constitutes the physical reason for the improvement of the nuclear shell structure.

We introduce a potential new working reference material – natural zircon megacrysts from an Early Pliocene alkaline basalt (from Penglai, northern Hainan Island, southern China) – for the microbeam determination of O and Hf isotopes, and U–Pb age dating. The Penglai zircon megacrysts were found to be fairly homogeneous in Hf and O isotopes based on large numbers of measurements by LA‐multiple collector (MC)‐ICP‐MS and SIMS, respectively. Precise determinations of O isotopes by isotope ratio mass spectrometry (IRMS) and Hf isotopes by solution MC‐ICP‐MS were in good agreement with the statistical mean of microbeam measurements. The mean δ18O value of 5.31 ± 0.10‰ (2s) by IRMS and the mean 176Hf/177Hf value of 0.282906 ± 0.0000010 (2s) by solution MC‐ICP‐MS are the best reference values for the Penglai zircons. SIMS and isotope dilution‐TIMS measurements yielded consistent 206Pb/238U ages within analytical uncertainties, and the preferred 206Pb/238U age was found to be 4.4 ± 0.1 Ma (95% confidence interval). The young age and variably high common Pb content make the Penglai zircons unsuitable as a primary U–Pb age reference material for calibration of unknown samples by microbeam analysis; however, they can be used as a secondary working reference material for quality control of U–Pb age determination for young (particularly < 10 Ma) zircon samples.

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The evolution of nuclear shell structure is investigated for the first time within density-dependent relativistic Hartree-Fock theory and the role of π-exchange potential is studied in detail. The energy differences between the neutron orbits ν1h 9/2 , ν1i 13/2 in the N = 82 isotones and between the proton ones π1g 7/2 , π1h 11/2 in the Z = 50 isotopes are extracted as a function of neutron excess N − Z. A kink around Z = 58 for the N = 82 isotones is found as an effect resulting from pion correlations. It is shown that the inclusion of π-coupling plays a central role to provide realistic isospin dependence of the energy differences. In particular, the tensor part of the π-coupling has an important effect on the characteristic isospin dependence observed in recent experiments.PACS numbers: 21.30. Fe, 21.60.Jz, 21.10.Dr, 24.10.Cn, 24.10.Jv The nucleon-nucleon bare interaction at low and medium energies is originally induced by the meson exchange processes as predicted by Yukawa [1]. In the nuclear medium, it is strongly renormalized by medium effects which lead to the effective nucleonnucleon interaction. A large part of the present understanding of nuclear structure is based on selfconsistent mean field descriptions making use of effective interactions directly parametrized so as to reproduce selected nuclear properties. The two most successful categories are the non-relativistic HartreeFock approaches [2,3,4,5] and the Relativistic Mean Field (RMF) approaches [6,7,8]. Using these models, many nuclear structure properties are calculated in the whole region of the nuclear chart with these effective interactions. During the past decade, great successes have been achieved by the RMF theory not only in stable nuclei but also in exotic regions [9,10,11,12,13,14,15,16,17]. Of special interest is the fact that the RMF model provides a natural mechanism for explaining the spin-orbit splittings of single-particle levels. This feature becomes even more of central importance with the experimental observation that nuclei near drip lines undergo modifications of their shell structure, where the spin-orbit potential must play an essential role.One of the basic open problems is the role of one-pion exchange process, which is known to play a fundamental role in the meson-exchange interaction. However, the RMF model is not the appropriate framework to study pion-related processes because it is essentially a Hartree approximation where the Fock (exchange) contributions are altogether dropped, while the Hartree (direct) contributions of pions are zero due to the parity conservation in spherical and axially deformed nuclei. Recent progress in the relativistic Hartree-Fock description of nuclear structure, namely the density-dependent relativistic HartreeFock (DDRHF) approach [18] has brought a new insight to consider this problem. Within the DDRHF * Electronic address: whlong@pku.org.cn theory, the effective meson-nucleon coupling strengths including the one-pion exchange are determined in a similar way to the RMF model and a qu...

The β-decay half-lives of neutron-rich nuclei with 20 Z 50 are systematically investigated using the newly developed fully self-consistent proton-neutron quasiparticle random phase approximation (QRPA), based on the spherical relativistic Hartree-Fock-Bogoliubov (RHFB) framework. Available data are reproduced by including an isospin-dependent proton-neutron pairing interaction in the isoscalar channel of the RHFB+QRPA model. With the calculated β-decay half-lives of neutron-rich nuclei a remarkable speeding up of r-matter flow is predicted. This leads to enhanced r-process abundances of elements with A 140, an important result for the understanding of the origin of heavy elements in the universe.