Probing The Exotic Structure Of Nuclei In The Relativistic Point-coupling Model By Complex-momentum-representation Method

Resonance is one of the most concerned phenomena in physics,which has been widely found in atomic,molecular,and nuclear physics.The Fermi surfaces of exotic nuclei are close to the continuum,so the resonances play important roles in the formation of many exotic nuclear phenomena,such as halo,giant halo,and deformed halo.So studying the single-particle resonant states helps people understand the exotic phenomena and exotic structure in the nuclei.The study on the resonances achieved more and more attention in nuclear physics during recent years.In order to study the resonant phenomenon in the exotic structure of nuclei,we have developed a new method,namely,the complex momentum representation(CMR)method is used to study the single-particle resonant states in the relativistic point-coupling model.The related theoretical formulas are deduced,and the numerical calculation code is written with Fortran software,so that the Dirac equation in the relativistic point-coupling model is transformed into the momentum representation to obtain the resonant states and the bound states we needFirstly,the important role of resonant states in the exotic structure of nuclei,the research methods and progress of single-particle resonant states,and the development of the relativistic mean-field(RMF)theory in recent years are briefly described.Since the relativistic point-coupling model is very successful in describing various nuclear phenomena and the CMR is an efficient method for describing single-particle resonant states,so the focus of this work is to probe the resonance of Dirac particle in the relativistic point-coupling model by CMR methodSecondly,the theoretical framework of this paper is introduced.Including the point-coupling model of relativistic mean-field theory(RMF-PC),the complex momentum representation(CMR)method,and combining the two to establish the theoretical method of the relativistic point-coupling model of complex-momentum-representation method(RMF(PC)-CMR).The model method can be used to study the single-particle resonant states of the nuclei.The theoretical formula of the model method and the details of numerical calculation are also givenThirdly,the relativistic point-coupling model of complex-momentum-representation was used to study the single-particle resonant states of spherical nucleus 120Sn.We take the 120Sn nucleus as an example,the resonant energies and resonant widths,and the wave function in the momentum space are calculated,and compared the results with the calculation results of other methods.Our results get a good agreement with those of other methods.In particular,the method is not only very effective for calculating narrow resonances,but also can be reliably applied to broad resonances.In addition,the resonant states are predicted accurately with the CMR method even for those lying near the continuum threshold.Therefore,this model method is a good method for solving single-particle resonant statesLastly,the relativistic point-coupling model of complex-momentum-representation was used to systematically study the isotopic chain of nucleus Sn.By studying the single-particle resonant states of spherical nucleus 120Sn,the model method is a good method to solve the resonant states.Immediately,taking Sn isotopes as examples,the resonant energies and widths are systematically calculated and compared with those from the Green's function method.Our results are also in excellent agreement with those of the Green's function method The predicted resonant energies and widths generally decrease with the increase of neutron number,which are mainly induced by the different potentials of Sn isotopes.Moreover,the radial-momentum probability distributions of the single-particle states and their density distributions in the coordinate space are also calculated.Well localized wave functions are found in the momentum space for the resonant states,while the density distributions of the resonant states have long tails in the coordinate space,which indicates the advantage of CMR method in studying the properties of resonant states.