用相对论平均场方法对~(12)C、~(16)O、~(40)Ca和~(208)Pb的单K ^-核态和多K巴核态进行了自洽计算。p波共振σ(1385)激发的梯度项在平均场概念可接受的单K ^-核系统中起次要作用。在超过100 MeV的深束缚能范围内,当衰变通道Kbar N-> pi Sigma关闭时,Kbar N -> pi Lambda转换模式和非介子Kbar NN -> YN转换模式(假定它们遵循ρ ^2密度依赖性)的重要贡献得到了评估。总的来说,当单个K ^-核的结合能超过100 MeV时,我们得到K^-核的总衰变宽度为50-100 MeV。多Kbar核计算表明,随着嵌入核介质中的Kbar介子数目的增加,每个Kbar介子的结合能饱和。核密度和Kbar密度仅适度增加并接近饱和,没有任何K介子凝聚前体的迹象。
英文摘要:
We report on self-consistent calculations of single-K^- nuclear states and multi-Kbar nuclear states in 12C, 16O, 40Ca and 208Pb within the relativistic mean-field (RMF) approach. Gradient terms motivated by the p-wave resonance Sigma(1385) are found to play a secondary role for single-K^- nuclear systems where the mean-field concept is acceptable. Significant contributions from the Kbar N -> pi Lambda conversion mode, and from the nonmesonic Kbar NN -> YN conversion modes which are assumed to follow a rho^2 density dependence, are evaluated for the deep binding-energy range of over 100 MeV where the decay channel Kbar N -> pi Sigma is closed. Altogether we obtain K^- total decay widths of 50-100 MeV for binding energies exceeding 100 MeV in single-K^- nuclei. Multi-Kbar nuclear calculations indicate that the binding energy per Kbar meson saturates upon increasing the number of Kbar mesons embedded in the nuclear medium. The nuclear and Kbar densities increase only moderately and are close to saturation, with no indication of any kaon-condensation precursor.
The cross sections for the deep sub-barrier fusion reaction of light nuclei are calculated within the theoretical framework of the selective resonant tunneling model. In this model, assumption of a complex square-well nuclear potential is invoked to describe the absorption inside the nuclear well. The theoretical estimates for these cross sections agree well with the experimentally measured values. The features of the astrophysical S-factor are derived in terms of this model. Present formalism appears to be particularly useful for the low energy resonant reactions between two charged nuclei.
We report on self-consistent calculations of $\bar{p}$ quasi-bound states in selected nuclei performed within the relativistic mean-field (RMF) model employing $\bar{p}$ coupling constants tuned to reproduce $\bar{p}$-atom data. We confirmed considerable polarization of the nuclear core induced by the antiproton. The $\bar{p}$ annihilation was treated dynamically, taking into account the reduced phase space in the nuclear medium as well as the compressed nuclear density. The energy available for the annihilation products was evaluated self-consistently, considering additional energy shift due …
Many-body correlations play an essential role in the ab initio description of nuclei with nuclear bare interactions. We propose a new framework to describe light nuclei by the hybridization of the tensor-optimized antisymmetrized molecular dynamics (TOAMD) and the high-momentum AMD (HM-AMD), which we call "HM-TOAMD". In this framework, we describe the many-body correlations in terms of not only the correlation functions in TOAMD, but also the high-momentum pairs in the AMD wave function. With the bare nucleon-nucleon interaction AV8', we sufficiently reproduce the energy and radius of the 3H n…
We present the results of charged current quasielastic(CCQE) scattering cross sections from free as well as bound nucleons like in $^{12}C$, $^{16}O$, $^{40}Ar$ and $^{208}Pb$ nuclear targets in $E_ν(_{\barν})~\le~ $1 GeV energy region. The results are obtained using local Fermi gas model with and without RPA effect. The differences those may arise in the electron and muon production cross sections due to the different lepton mass, uncertainties in the axial dipole mass $M_A$ and pseudoscalar form factor, and due to the inclusion of second class currents have been highlighted for neutrino/anti…
The energy spectra of light-mass kaonic nuclei were investigated using the theoretical framework of the $0s$-orbital model with zero-range $\bar{K} N$ and $\bar{K}\bar{K}$ interactions of effective single-channel real potentials. The energies of the $\bar{K} NN$, $\bar{K} NNN$, $\bar{K} NNNN$, $\bar{K}\bar{K} N$, and $\bar{K}\bar{K} NN$ systems were calculated in the cases of weak- and deep-binding of the $\bar{K} N$ interaction, which was adjusted to fit the $Λ(1405)$ mass with the energy of the $\bar{K} N$ bound state. The results qualitatively reproduced the energy systematics of kaonic nuc…
We present our latest calculations of $K^-$-nuclear quasi-bound states using a self-consistent scheme for constructing $K^-$-nuclear potentials from various subthreshold chirally inspired $\bar{K}N$ scattering amplitudes. We consider in-medium versions of the scattering amplitudes taking into account Pauli blocking in the intermediate states. The resulting $K^-$ binding energies as well as the widths exhibit the same A dependence, however, the binding energies strongly depend on the model used.
The concept of fission barrier - a parameter which enters in quantitative estimates of various observables related to nuclear fission - is presented from the point of view of theory based on the picture of nuclear deformation and energy dependent on it. We describe the macroscopic-microscopic method of calculating energy landscapes which is simpler than the selfconsistent mean field approach, and, due to its two-component nature, seems to be easier to adjust to experimental data. We present some models and methods used to find the fission saddles. For the purpose of illustration, we present re…
Static fission barriers for 95 even-even transuranium nuclei with charge number $Z=94-118$ have been systematically investigated by means of pairing self-consistent Woods-Saxon-Strutinsky calculations using the potential energy surface approach in multidimensional ($β_2$, $γ$, $β_4$) deformation space. Taking the heavier $^{252}$Cf nucleus (with the available fission barrier from experiment) as an example, the formation of the fission barrier and the influence of macroscopic, shell and pairing correction energies on it are analyzed. The results of the present calculated $β_2$ values and barrie…
We employ density-dependent relativistic mean-field theory to study how the triaxiality and pairing interaction affect the inner fission barriers of actinide nuclei. It was found that triaxiality reduced the inner fission barriers and improved agreement with experimental values for many actinides. However, about 1-2 MeV discrepancy to the experimental values still remained for some of the considered nuclei. Such a discrepancy could be made further smaller by increasing the BCS pairing strength parameter. In this work, we demonstrated that adjusting the paring strength was effective to reproduc…
Background: Fission barriers of actinide nuclei have been mostly and for long been microscopi- cally calculated for even-even fissioning systems. Calculations in the case of odd nuclei have been performed merely within a so-called equal-filling approximation (EFA) as opposed to an approach taking explicitly into account the time reversal breaking properties at the mean field level- and for only one single-particle configuration. Purpose: We study the dependence of the fission barriers on various relevant configurations (e.g. to evaluate the so-called specialization energy). Besides, we want to…
Above-barrier fusion cross-sections for an isotopic chain of oxygen isotopes with A=16-19 incident on a $^{12}$C target are presented. Experimental data are compared with both static and dynamical microscopic calculations. These calculations are unable to explain the $\sim$37\% increase in the average above-barrier fusion cross-section observed for $^{19}$O as compared to $β$-stable oxygen isotopes. This result suggests that for neutron-rich nuclei existing time-dependent Hartree-Fock calculations underpredict the role of dynamics at near-barrier energies. High-quality measurement of above-bar…
Excitations of the unstable nuclei ^{48}Ni and ^{49}Ni
The isoscalar E1 and E2 resonances in the proton-rich nuclei ^{48,49}Ni and the { f_{7/2} 3^-} multiplet in ^{49}Ni have been calculated taking into account the single-particle continuum exactly. The analogous calculations for the mirror nuclei ^{48}Ca and ^{49}Sc are presented. The models used are the continuum RPA for ^{48}Ni, ^{48}Ca and the Odd RPA for ^{49}Ni, ^{49}Sc, the latter has been developed recently and describes both single-particle and collective excitations of an odd nucleus on a common basis. In all four nuclei we obtained a distinct splitting of the isoscalar E1 resonance int…
We have studied strength in the BCS pairing force, used as a residual interaction to the relativistic mean-field to reproduce the height of the inner fission barriers for actinide nuclei. It was found that increasing the pairing strength by about 13% makes reproduce the inner fission barriers better over a wide range of actinide nuclei. This result was verified by using the moment-of-inertia of pairing rotational energy, which was introduced to avoid mean-field and odd-mass effects in the pairing interaction to deduce purely the pairing strength. The pairing interaction thus determined could s…
The double folding (DF) approach is one of the widely used methods for finding nucleus-nucleus interaction potential. In the present work, the influence of the nuclear matter density on the DF potential and on the Coulomb barrier parameters is studied systematically for collisions of spherical nuclei. The value of the parameter $B_Z=Z_P Z_T/(A_P^{1/3}+A_T^{1/3})$ (estimating the Coulomb barrier height) varies in these calculations from 10 MeV up to 150 MeV. The novel feature of this study is that the nuclear densities came from the Relativistic Mean Field approach (RMF). For the nucleon-nucleo…
Potential Energy Surfaces of Actinide Nuclei from a Multi-dimensional Constraint Covariant Density Functional Theory: Barrier Heights and Saddle Point Shapes
A study of bound states of $η, η^{'}, D^{0}$, $\bar{D^{0}}$, $B^{0}$, $\bar{B^{0}}$, $\bar{K^{0}}$ and $ϕ$ mesons with light and heavy nuclei within chiral SU(3) model
In this contribution we review the dynamics of hyperons with nucleons and nuclear matter, paying a special attention to hypernuclei. We also discuss the presence of hyperons in the inner core of neutron stars and the consequences for the structure of these compact stars.
Antiproton scattering off $^3 He$ and $^4 He$ nuclei at low and intermediate energies
利用Jülich模型的$\bar N N$振幅作为输入,在Glauber-Sitenko方法中考虑了束流能量低于300 MeV时反质子在$^3\He$和$^4\He$靶上的散射.得到了与现有的$\bar p ^4\He$微分截面、$\bar p ^3\He$和$\pbar ^4\He$反应截面数据的良好一致性。极化总$\bar p ^3$他截面的预测,计算内的单散射近似,包括库仑核干涉效应。极化建立的动力学进行了讨论。
The thermal description of light nuclei at the chemical freeze-out has been investigated. First, I have verified the equilibration of the light nuclei and then introduced a new method to investigate the light nuclei formation. One can study the proximity between the phase space density of light nuclei ratios and their hadronic constituents e.g $\bar{d}/d$ and $(\bar{p}\bar{n}/pn)$. I have found that with the exclusion of the decay feed-down from the hadronic yields in the thermal model, the hadronic representations have good agreement with the light nuclei ratios. I have performed a similar an…
We study the inclusive photoproduction of $T_{{\bar c}{\bar c}}(3875)^-$ mesons (which are the antiparticles of the doubly charmed tetraquarks $T_{cc}(3875)^+$ discovered recently by the LHCb Collaboration) from nuclei in the near-threshold energy region within the nuclear spectral function approach by considering incoherent direct ($γp(n) \to D^+(D^0){T_{{\bar c}{\bar c}}(3875)^-}Λ^+_c$) photon--nucleon $T_{{\bar c}{\bar c}}(3875)^-$ creation processes as well as five possible different scenarios for their internal structure with the main goal of clarifying the possibility to decipher this st…
A recent RIKEN experiment on the quenched $g_A$ in the superallowed Gamow-Telller transition from $^{100}$Sn indicates a role of scale anomaly encoded in the anomalous dimension $β^\prime$ of the gluonic stress tensor ${\rm Tr \ G}_{μν}^2$. This observation provides a support to the notion of hidden scale symmetry emerging by strong nuclear correlations with an IR fixed point realized -- in the chiral limit -- in the Nambu-Goldstone mode. We suggest there is an analogy in the way scale symmetry manifests in nuclear medium to the continuity from the unitarity limit at low density (in light nucl…