In this work,the characteristics of 2νββ decays for six nuclei(36Ar,46Ca,48Ca,50Cr,70Zn,and 136Xe)in a mass range from A=36 to A=136 are studied within the nuclear shell model(NSM)framework.Calculations are present...In this work,the characteristics of 2νββ decays for six nuclei(36Ar,46Ca,48Ca,50Cr,70Zn,and 136Xe)in a mass range from A=36 to A=136 are studied within the nuclear shell model(NSM)framework.Calculations are presented for the half-lives,nuclear matrix elements(NMEs),phase space factors(G2ν),and convergence of the NMEs.The theoretical results agree well with the experimental data.In addition,we predict the half-lives of 2νββ decays for four nuclei.We focus on the convergence of the NMEs by analyzing the number of contributing intermediate 1+states(NC)for the nuclei of interest.We assume that NC is safely determined when the accumulated NMEs saturate 99.7%of the final calculated magnitude.From the calculations of the involved nuclei,we discover a connection between NC and the total number of intermediate 1+states(NT).According to the least squares fit,we conclude that the correlation is NC=(10.8±1.2)×N(0.29±0.02)T.展开更多
We present analytical method to calculate single particle matrix elements used in atomic and nuclear physics. We show seven different formulas of matrix elements of the operator f(r)d_r^m where f(r) = r~μ, r~μjJ(qr)...We present analytical method to calculate single particle matrix elements used in atomic and nuclear physics. We show seven different formulas of matrix elements of the operator f(r)d_r^m where f(r) = r~μ, r~μjJ(qr), V(r)corresponding to the Gaussian and the Yukawa potentials used in nuclear shell models and nuclear structure. In addition,we take into account a general integral formula of the matrix element 〈 n′ l′|f(r) d_r^(m) |n l〉 that covers all seven matrix elements obtained analytically.展开更多
Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn...Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn nuclear force,we analyze the dependence of the nuclear matrix elements on the isovector and isoscalar parts of proton–neutron particle–particle interactions.The dependence on the different nuclear matrix elements is observed,and the results are explained.We also provide the phase space factors using numerical electron wavefunctions and properly chosen excitation energies.Finally,we present our results for the half-lives of this decay mode for different nuclei.展开更多
The search for neutrinoless double-beta decay(0 b)represents one of the most compelling challenges in modern physics.Observ-ing this elusive nuclear process would not only confirm that neu-trinos are Majorana particle...The search for neutrinoless double-beta decay(0 b)represents one of the most compelling challenges in modern physics.Observ-ing this elusive nuclear process would not only confirm that neu-trinos are Majorana particles-their own antiparticles-but also provide definitive evidence of lepton number violation,offering critical insights into the matter-antimatter asymmetry of the universe.Despite decades of experimental efforts,no conclusive signal has been detected.A key obstacle lies in the persistent theoretical uncertainties surrounding predicted decay rates,which stem pri-marily from the calculation of nuclear matrix elements(NMEs)-the quantum-mechanical factors governing how the decay unfolds within complex nuclei.A major unresolved issue has been the missing short-range contribution,which arises from nucleon over-lap effects and cannot be deduced from long-range pion-exchange interactions alone.展开更多
基金Supported by National Natural Science Foundation of China(11647086,11647085)Shanxi Province Science Foundation for Youths(201901D211252)+1 种基金Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2019L0554,2019L0505)the Natural Science Research Fund of North University of China(XJJ201811)。
文摘In this work,the characteristics of 2νββ decays for six nuclei(36Ar,46Ca,48Ca,50Cr,70Zn,and 136Xe)in a mass range from A=36 to A=136 are studied within the nuclear shell model(NSM)framework.Calculations are presented for the half-lives,nuclear matrix elements(NMEs),phase space factors(G2ν),and convergence of the NMEs.The theoretical results agree well with the experimental data.In addition,we predict the half-lives of 2νββ decays for four nuclei.We focus on the convergence of the NMEs by analyzing the number of contributing intermediate 1+states(NC)for the nuclei of interest.We assume that NC is safely determined when the accumulated NMEs saturate 99.7%of the final calculated magnitude.From the calculations of the involved nuclei,we discover a connection between NC and the total number of intermediate 1+states(NT).According to the least squares fit,we conclude that the correlation is NC=(10.8±1.2)×N(0.29±0.02)T.
文摘We present analytical method to calculate single particle matrix elements used in atomic and nuclear physics. We show seven different formulas of matrix elements of the operator f(r)d_r^m where f(r) = r~μ, r~μjJ(qr), V(r)corresponding to the Gaussian and the Yukawa potentials used in nuclear shell models and nuclear structure. In addition,we take into account a general integral formula of the matrix element 〈 n′ l′|f(r) d_r^(m) |n l〉 that covers all seven matrix elements obtained analytically.
基金Supported by National Natural Science Foundation of China(11505078,1164730)“Light of West China”Program and key research program(XDPB09-2)from Chinese Academy of Sciences。
文摘Using partially restored isospin symmetry,we calculate the nuclear matrix elements for a special decay mode of a two-neutrino double beta decay–the decay to the first 2+excited states.Employing the realistic CD–Bonn nuclear force,we analyze the dependence of the nuclear matrix elements on the isovector and isoscalar parts of proton–neutron particle–particle interactions.The dependence on the different nuclear matrix elements is observed,and the results are explained.We also provide the phase space factors using numerical electron wavefunctions and properly chosen excitation energies.Finally,we present our results for the half-lives of this decay mode for different nuclei.
文摘The search for neutrinoless double-beta decay(0 b)represents one of the most compelling challenges in modern physics.Observ-ing this elusive nuclear process would not only confirm that neu-trinos are Majorana particles-their own antiparticles-but also provide definitive evidence of lepton number violation,offering critical insights into the matter-antimatter asymmetry of the universe.Despite decades of experimental efforts,no conclusive signal has been detected.A key obstacle lies in the persistent theoretical uncertainties surrounding predicted decay rates,which stem pri-marily from the calculation of nuclear matrix elements(NMEs)-the quantum-mechanical factors governing how the decay unfolds within complex nuclei.A major unresolved issue has been the missing short-range contribution,which arises from nucleon over-lap effects and cannot be deduced from long-range pion-exchange interactions alone.
