Pub Date : 2024-08-12DOI: 10.1103/physrevc.110.024308
Z. C. Xu, R. Z. Hu, S. L. Jin, J. H. Hou, S. Zhang, F. R. Xu
Neutron-rich nuclei are attracting significant attention due to vital roles in the nucleosynthesis processes of the universe. The shell evolution which breaks or creates magic numbers in some instances leads to shape coexistence that frequently serves as a portal to the islands of inversion (IOI). was suggested as a northern extension of the IOI across , and a new IOI around (–28) had also been predicted. We have performed ab initio calculations for even-even Zn isotopes and () isotones located in the north of the and 50 IOIs. With a chiral two- plus three-nucleon force, the shell-model valence-space effective Hamiltonian is derived using the many-body perturbation theory named -box folded diagrams, and the effective operators of electromagnetic transitions are obtained using similar -box folded diagrams. The calculations reproduce experimental excitation energies and electric qudrupole transition strengths of excited states of the nuclei, showing a collectivity of isotopes and a noncollectivity of the () isotones.
{"title":"Collectivity of nuclei near the exotic doubly magic Ni78 by ab initio calculations","authors":"Z. C. Xu, R. Z. Hu, S. L. Jin, J. H. Hou, S. Zhang, F. R. Xu","doi":"10.1103/physrevc.110.024308","DOIUrl":"https://doi.org/10.1103/physrevc.110.024308","url":null,"abstract":"Neutron-rich nuclei are attracting significant attention due to vital roles in the nucleosynthesis processes of the universe. The shell evolution which breaks or creates magic numbers in some instances leads to shape coexistence that frequently serves as a portal to the islands of inversion (IOI). <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mmultiscripts><mi>Zn</mi><mprescripts></mprescripts><none></none><mn>74</mn></mmultiscripts></math> was suggested as a northern extension of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>40</mn></mrow></math> IOI across <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>28</mn></mrow></math>, and a new IOI around <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>50</mn></mrow></math> (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>20</mn></mrow></math>–28) had also been predicted. We have performed <i>ab initio</i> calculations for even-even Zn isotopes and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>50</mn></mrow></math> (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>></mo><mn>28</mn></mrow></math>) isotones located in the north of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>40</mn></mrow></math> and 50 IOIs. With a chiral two- plus three-nucleon force, the shell-model valence-space effective Hamiltonian is derived using the many-body perturbation theory named <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mover accent=\"true\"><mi mathvariant=\"normal\">Q</mi><mo>̂</mo></mover></math>-box folded diagrams, and the effective operators of electromagnetic transitions are obtained using similar <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mover accent=\"true\"><mi mathvariant=\"normal\">Θ</mi><mo>̂</mo></mover></math>-box folded diagrams. The calculations reproduce experimental excitation energies and electric qudrupole transition strengths of excited states of the nuclei, showing a collectivity of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mmultiscripts><mi>Zn</mi><mprescripts></mprescripts><none></none><mrow><mn>70</mn><mtext>−</mtext><mn>78</mn></mrow></mmultiscripts></math> isotopes and a noncollectivity of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>50</mn></mrow></math> (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>></mo><mn>28</mn></mrow></math>) isotones.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.1103/physrevc.110.024606
H. Lee, P. McGlynn, C. Simenel
Background: Quasifission reactions occur in fully damped heavy-ion collisions without the formation of an equilibrated compound nucleus, leading to the formation of fragments with properties similar to those in fission reactions. In particular, similar shell effects are expected to affect fragment formation in both fission and quasifission. Experimentally, the role of shell effects in quasifission is still debated, and further theoretical predictions are needed.
{"title":"Shell effects in quasifission in reactions forming the Th226 compound nucleus","authors":"H. Lee, P. McGlynn, C. Simenel","doi":"10.1103/physrevc.110.024606","DOIUrl":"https://doi.org/10.1103/physrevc.110.024606","url":null,"abstract":"<b>Background:</b> Quasifission reactions occur in fully damped heavy-ion collisions without the formation of an equilibrated compound nucleus, leading to the formation of fragments with properties similar to those in fission reactions. In particular, similar shell effects are expected to affect fragment formation in both fission and quasifission. Experimentally, the role of shell effects in quasifission is still debated, and further theoretical predictions are needed.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141938016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1103/physrevc.110.025502
M. Martini, M. Ericson, G. Chanfray
We discuss the electron and muon neutrino and antineutrino double-differential cross sections on carbon in the quasielastic as well as in the multinucleon and one pion production channels. By projecting them in the transferred momentum—transferred energy plane and in the neutrino energy—lepton scattering angle plane, as well as by performing simple considerations on the position of the quasielastic and Delta peaks and on their broadening, we explain the surprising dominance of the muon neutrino and antineutrino cross sections over the electron ones in particular kinematical conditions.
{"title":"Phase space of electron- and muon-neutrino and antineutrino scattering off nuclei","authors":"M. Martini, M. Ericson, G. Chanfray","doi":"10.1103/physrevc.110.025502","DOIUrl":"https://doi.org/10.1103/physrevc.110.025502","url":null,"abstract":"We discuss the electron and muon neutrino and antineutrino double-differential cross sections on carbon in the quasielastic as well as in the multinucleon and one pion production channels. By projecting them in the transferred momentum—transferred energy plane and in the neutrino energy—lepton scattering angle plane, as well as by performing simple considerations on the position of the quasielastic and Delta peaks and on their broadening, we explain the surprising dominance of the muon neutrino and antineutrino cross sections over the electron ones in particular kinematical conditions.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1103/physrevc.110.024304
K. Nomura
The low-energy nuclear structure and two-neutrino double- () decay are studied within the interacting boson model (IBM) that is based on the nuclear energy density functional (EDF). The IBM Hamiltonian describing the initial and final even-even nuclei, and the interacting boson fermion-fermion Hamiltonian producing the intermediate states of the neighboring odd-odd nuclei are determined by the microscopic inputs provided by the self-consistent mean-field (SCMF) calculations employing a relativistic EDF and a separable pairing force. Sensitivities of the low-lying structure and -decay properties to the pairing strength are specifically analyzed. It is shown that the SCMF calculations with decreased and increased pairing strengths lead to quadrupole-quadrupole interaction strengths in the IBM that are, respectively, significantly enhanced and reduced in magnitude. When the increased pairing is adopted, in particular, the energy levels of the excited states are lowered, and the predicted -decay nuclear matrix elements (NMEs) increase in magnitude systematically. The mapped IBM employing the increased pairing force generates effective NMEs and half-lives that are in a reasonable agreement with the experimental data for the , and decays in particular, whereas the calculation with the standard pairing strength is adequate to provide an overall good description of the effective NMEs in agreement with data.
在基于核能量密度函数（EDF）的相互作用玻色子模型（IBM）中研究了低能核结构和双中微子双β（2νββ）衰变。描述初始和最终偶-偶核的 IBM 哈密顿方程，以及产生邻近奇-偶核中间状态的相互作用玻色子-费米子哈密顿方程，都是由采用相对论能量密度函数和可分离配对力的自洽均场计算所提供的微观输入决定的。具体分析了低洼结构和 2νββ 衰变特性对配对力的敏感性。结果表明，配对强度减小和增大的 SCMF 计算导致 IBM 中的四极-四极相互作用强度分别显著增强和减小。特别是当采用增加配对时，激发的 0+ 态能级降低，预测的 2νββ 衰变核矩阵元素（NMEs）的量级系统地增加。采用增加配对力的映射 IBM 产生的有效核矩阵元素和半衰期与 Ge76→Se76、Se82→Kr82 和 Mo100→Ru100 衰变的实验数据相当吻合，而采用标准配对力的计算则足以提供与数据吻合的有效核矩阵元素的总体良好描述。
{"title":"Effects of pairing strength on the nuclear structure and double-β decay predictions within the mapped interacting boson model","authors":"K. Nomura","doi":"10.1103/physrevc.110.024304","DOIUrl":"https://doi.org/10.1103/physrevc.110.024304","url":null,"abstract":"The low-energy nuclear structure and two-neutrino double-<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>β</mi></math> (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>2</mn><mi>ν</mi><mi>β</mi><mi>β</mi></mrow></math>) decay are studied within the interacting boson model (IBM) that is based on the nuclear energy density functional (EDF). The IBM Hamiltonian describing the initial and final even-even nuclei, and the interacting boson fermion-fermion Hamiltonian producing the intermediate states of the neighboring odd-odd nuclei are determined by the microscopic inputs provided by the self-consistent mean-field (SCMF) calculations employing a relativistic EDF and a separable pairing force. Sensitivities of the low-lying structure and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>2</mn><mi>ν</mi><mi>β</mi><mi>β</mi></mrow></math>-decay properties to the pairing strength are specifically analyzed. It is shown that the SCMF calculations with decreased and increased pairing strengths lead to quadrupole-quadrupole interaction strengths in the IBM that are, respectively, significantly enhanced and reduced in magnitude. When the increased pairing is adopted, in particular, the energy levels of the excited <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>0</mn><mo>+</mo></msup></math> states are lowered, and the predicted <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>2</mn><mi>ν</mi><mi>β</mi><mi>β</mi></mrow></math>-decay nuclear matrix elements (NMEs) increase in magnitude systematically. The mapped IBM employing the increased pairing force generates effective NMEs and half-lives that are in a reasonable agreement with the experimental data for the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>Ge</mi><mprescripts></mprescripts><none></none><mn>76</mn></mmultiscripts><mo>→</mo><mmultiscripts><mi>Se</mi><mprescripts></mprescripts><none></none><mn>76</mn></mmultiscripts></mrow><mo>,</mo><mo> </mo><mrow><mmultiscripts><mi>Se</mi><mprescripts></mprescripts><none></none><mn>82</mn></mmultiscripts><mo>→</mo><mmultiscripts><mi>Kr</mi><mprescripts></mprescripts><none></none><mn>82</mn></mmultiscripts></mrow></math>, and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>Mo</mi><mprescripts></mprescripts><none></none><mn>100</mn></mmultiscripts><mo>→</mo><mmultiscripts><mi>Ru</mi><mprescripts></mprescripts><none></none><mn>100</mn></mmultiscripts></mrow></math> decays in particular, whereas the calculation with the standard pairing strength is adequate to provide an overall good description of the effective NMEs in agreement with data.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-08DOI: 10.1103/physrevc.110.025204
Jan A. Fotakis, Jakob E. Lohr, Carsten Greiner
We present exact relations between the diffusion coefficients or conductivities, , of strongly interacting matter. We show that once the diagonal entries are known in two different charge representations, the off-diagonal coefficients are functions of the diagonal entries once isospin symmetry applies. As an important example, we infer the conductivities on the basis of available calculations from lattice quantum chromodynamics and argue that these computations suffer under the approximations made to achieve them. Further, we argue that the representation of the conductivities with respect to the conserved quark flavors may deliver more insight into the chemical composition of strongly interacting matter.
{"title":"Exact relations between the conductivities and their connection to the chemical composition of QCD matter","authors":"Jan A. Fotakis, Jakob E. Lohr, Carsten Greiner","doi":"10.1103/physrevc.110.025204","DOIUrl":"https://doi.org/10.1103/physrevc.110.025204","url":null,"abstract":"We present exact relations between the diffusion coefficients or conductivities, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msub><mi>κ</mi><mrow><mi>q</mi><msup><mi>q</mi><mo>′</mo></msup></mrow></msub><mo>/</mo><mi>T</mi><mo>=</mo><msub><mi>σ</mi><mrow><mi>q</mi><msup><mi>q</mi><mo>′</mo></msup></mrow></msub></mrow></math>, of strongly interacting matter. We show that once the diagonal entries are known in two different charge representations, the off-diagonal coefficients are functions of the diagonal entries once isospin symmetry applies. As an important example, we infer the conductivities on the basis of available calculations from lattice quantum chromodynamics and argue that these computations suffer under the approximations made to achieve them. Further, we argue that the representation of the conductivities with respect to the conserved quark flavors may deliver more insight into the chemical composition of strongly interacting matter.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1103/physrevc.110.024302
Y. X. Zhang (张妍心), B. R. Liu (刘博然), K. Y. Zhang (张开元), J. M. Yao (尧江明)
We present a systematic study on the structural properties of odd- superheavy nuclei with proton numbers , and neutron numbers increasing from to the neutron dripline within the framework of axially deformed relativistic Hartree-Bogoliubov theory in continuum. The results are compared with those of even-even superheavy nuclei with proton numbers and 120. We analyze various bulk properties of their ground states, including binding energies, quadrupole deformations, root-mean-square radii, nucleon separation energies, and -decay energies. The coexistence of competing prolate and oblate or spherical shapes leads to abrupt changes in both quadrupole deformations and charge radii as functions of neutron numbers. Compared to even-even nuclei, the odd-mass ones exhibit a more complicated transition picture, in which the quantum numbers of of the lowest-energy configuration may change with deformation. This may result in the change of angular momentum in the ground-state to ground-state decay and thus quench the decay rate in odd-mass nuclei. Moreover, our results demonstrate a pronounced proton shell gap at , instead of , which is consistent with the predictions of most covariant density functional theories. Besides, large neutron shell gaps are found at and in the four isotopic chains, as well as at in the light two isotopic chains with and , attributed to the nearly degenerate and spin-orbit doublet states d
{"title":"Shell structure and shape transition in odd-Z superheavy nuclei with proton numbers Z=117, 119: Insights from applying deformed relativistic Hartree-Bogoliubov theory in continuum","authors":"Y. X. Zhang (张妍心), B. R. Liu (刘博然), K. Y. Zhang (张开元), J. M. Yao (尧江明)","doi":"10.1103/physrevc.110.024302","DOIUrl":"https://doi.org/10.1103/physrevc.110.024302","url":null,"abstract":"We present a systematic study on the structural properties of odd-<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Z</mi></math> superheavy nuclei with proton numbers <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>117</mn><mo>,</mo><mn>119</mn></mrow></math>, and neutron numbers <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>N</mi></math> increasing from <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>170</mn></mrow></math> to the neutron dripline within the framework of axially deformed relativistic Hartree-Bogoliubov theory in continuum. The results are compared with those of even-even superheavy nuclei with proton numbers <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>118</mn></mrow></math> and 120. We analyze various bulk properties of their ground states, including binding energies, quadrupole deformations, root-mean-square radii, nucleon separation energies, and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>α</mi></math>-decay energies. The coexistence of competing prolate and oblate or spherical shapes leads to abrupt changes in both quadrupole deformations and charge radii as functions of neutron numbers. Compared to even-even nuclei, the odd-mass ones exhibit a more complicated transition picture, in which the quantum numbers of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>K</mi><mi>π</mi></msup></math> of the lowest-energy configuration may change with deformation. This may result in the change of angular momentum in the ground-state to ground-state <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>α</mi></math> decay and thus quench the decay rate in odd-mass nuclei. Moreover, our results demonstrate a pronounced proton shell gap at <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>120</mn></mrow></math>, instead of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>114</mn></mrow></math>, which is consistent with the predictions of most covariant density functional theories. Besides, large neutron shell gaps are found at <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>172</mn></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>258</mn></mrow></math> in the four isotopic chains, as well as at <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>N</mi><mo>=</mo><mn>184</mn></mrow></math> in the light two isotopic chains with <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>117</mn></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>Z</mi><mo>=</mo><mn>118</mn></mrow></math>, attributed to the nearly degenerate <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>3</mn><mi>d</mi></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>4</mn><mi>p</mi></mrow></math> spin-orbit doublet states d","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1103/physrevc.110.025801
E. E. Kolomeitsev, D. N. Voskresensky
Analyses for the NICER data indicate that there is no significant variation of compact star radii within the mass range of 1.4 to 2.0 solar masses. Yamamoto et al. [Phys. Rev. C108, 035811 (2023)] concluded recently that “this feature cannot be reproduced by the hadronic matter due to the softening of the equation of state (EoS) by hyperon mixing, suggesting the possible existence of quark phases in neutron-star interiors.” Using a collection of 162 purely nucleonic, hyperonic, and quarkish EoSs from the CompOSE database and some other works, we verify that hyperons indeed lead to a significant difference in radii of stars of 1.4 and 2.0 solar masses, which diminishes in the presence of quarks. We compare the shapes of the mass-radius curves and show that hyperons and quarks in the neutron star cores prefer a particular curve shape with backbending. It is argued that the shape is controlled by the density dependence of the nuclear symmetry energy. We draw attention to the existence of a class of purely hadronic relativistic mean-field EoSs with scalar-field dependent hadron masses and coupling constants that satisfy the known constraints on the EoSs including the analyses of the new NICER data and the above requirement of insignificant variation of the neutron star radii.
{"title":"NICER data and a σ-field-dependent stiffness of the hadronic equation of state","authors":"E. E. Kolomeitsev, D. N. Voskresensky","doi":"10.1103/physrevc.110.025801","DOIUrl":"https://doi.org/10.1103/physrevc.110.025801","url":null,"abstract":"Analyses for the NICER data indicate that there is no significant variation of compact star radii within the mass range of 1.4 to 2.0 solar masses. Yamamoto <i>et al.</i> [<span>Phys. Rev. C</span> <b>108</b>, 035811 (2023)] concluded recently that “this feature cannot be reproduced by the hadronic matter due to the softening of the equation of state (EoS) by hyperon mixing, suggesting the possible existence of quark phases in neutron-star interiors.” Using a collection of 162 purely nucleonic, hyperonic, and quarkish EoSs from the CompOSE database and some other works, we verify that hyperons indeed lead to a significant difference in radii of stars of 1.4 and 2.0 solar masses, which diminishes in the presence of quarks. We compare the shapes of the mass-radius curves and show that hyperons and quarks in the neutron star cores prefer a particular curve shape with backbending. It is argued that the shape is controlled by the density dependence of the nuclear symmetry energy. We draw attention to the existence of a class of purely hadronic relativistic mean-field EoSs with scalar-field dependent hadron masses and coupling constants that satisfy the known constraints on the EoSs including the analyses of the new NICER data and the above requirement of insignificant variation of the neutron star radii.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1103/physrevc.110.025501
Beata E. Kowal, Krzysztof M. Graczyk, Artur M. Ankowski, Rwik Dharmapal Banerjee, Hemant Prasad, Jan T. Sobczyk
Employing the neural network framework, we obtain empirical fits to the electron-scattering cross sections for carbon over a broad kinematic region, extending from the quasielastic peak through resonance excitation to the onset of deep-inelastic scattering. We consider two different methods of obtaining such model-independent parametrizations and the corresponding uncertainties: based on the bootstrap approach and the Monte Carlo dropout approach. In our analysis, the defines the loss function, including point-to-point and normalization uncertainties for each independent set of measurements. Our statistical approaches lead to fits of comparable quality and similar uncertainties of the order of 7%. To test these models, we compare their predictions to test datasets excluded from the training process and theoretical predictions obtained within the spectral function approach. The predictions of both models agree with experimental measurements and theoretical calculations. We also perform a comparison to a dataset lying beyond the covered kinematic region, and find that the bootstrap approach shows better interpolation and extrapolation abilities than the one based on the dropout algorithm.
{"title":"Empirical fits to inclusive electron-carbon scattering data obtained by deep-learning methods","authors":"Beata E. Kowal, Krzysztof M. Graczyk, Artur M. Ankowski, Rwik Dharmapal Banerjee, Hemant Prasad, Jan T. Sobczyk","doi":"10.1103/physrevc.110.025501","DOIUrl":"https://doi.org/10.1103/physrevc.110.025501","url":null,"abstract":"Employing the neural network framework, we obtain empirical fits to the electron-scattering cross sections for carbon over a broad kinematic region, extending from the quasielastic peak through resonance excitation to the onset of deep-inelastic scattering. We consider two different methods of obtaining such model-independent parametrizations and the corresponding uncertainties: based on the bootstrap approach and the Monte Carlo dropout approach. In our analysis, the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>χ</mi><mn>2</mn></msup></math> defines the loss function, including point-to-point and normalization uncertainties for each independent set of measurements. Our statistical approaches lead to fits of comparable quality and similar uncertainties of the order of 7%. To test these models, we compare their predictions to test datasets excluded from the training process and theoretical predictions obtained within the spectral function approach. The predictions of both models agree with experimental measurements and theoretical calculations. We also perform a comparison to a dataset lying beyond the covered kinematic region, and find that the bootstrap approach shows better interpolation and extrapolation abilities than the one based on the dropout algorithm.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1103/physrevc.110.024605
Zongheng Li, Tao Li, Xu Wang
Nuclear Coulomb excitation is often calculated using a semiclassical (SC) approach, where the projectile follows classical trajectories and excites the target nucleus through a time-dependent Coulomb interaction. While the validity of the SC approach has been well established for electric quadrupole () transitions, its accuracy for higher-order multipole transitions remains insufficiently benchmarked. In this paper, we compare Coulomb excitation cross sections for higher-order multipole transitions calculated using the SC approach with those obtained through a quantum mechanical (QM) approach, where the projectile is described by wave functions. For transitions, the excitation cross sections from both approaches are of the same order of magnitude, consistent with existing validations. However, for higher-order multipole transitions, the SC approach yields significantly higher cross sections, deviating possibly by orders of magnitude from the QM results. This discrepancy underscores the necessity of the QM approach for accurate calculations of the Coulomb excitation cross sections. The failure of the SC approach is explained through using the Wentzel-Kramers-Brillouin approximation.
{"title":"Semiclassical approach for nuclear Coulomb excitation","authors":"Zongheng Li, Tao Li, Xu Wang","doi":"10.1103/physrevc.110.024605","DOIUrl":"https://doi.org/10.1103/physrevc.110.024605","url":null,"abstract":"Nuclear Coulomb excitation is often calculated using a semiclassical (SC) approach, where the projectile follows classical trajectories and excites the target nucleus through a time-dependent Coulomb interaction. While the validity of the SC approach has been well established for electric quadrupole (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>E</mi><mn>2</mn></mrow></math>) transitions, its accuracy for higher-order multipole transitions remains insufficiently benchmarked. In this paper, we compare Coulomb excitation cross sections for higher-order multipole transitions calculated using the SC approach with those obtained through a quantum mechanical (QM) approach, where the projectile is described by wave functions. For <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>E</mi><mn>2</mn></mrow></math> transitions, the excitation cross sections from both approaches are of the same order of magnitude, consistent with existing validations. However, for higher-order multipole transitions, the SC approach yields significantly higher cross sections, deviating possibly by orders of magnitude from the QM results. This discrepancy underscores the necessity of the QM approach for accurate calculations of the Coulomb excitation cross sections. The failure of the SC approach is explained through using the Wentzel-Kramers-Brillouin approximation.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.1103/physrevc.110.024901
Jia-Lin Pei (裴家琳), Guo-Liang Ma (马国亮), Adam Bzdak
Multiparticle cumulants method can be used to reveal long-range collectivity in small and large colliding systems. The four-particle symmetric cumulant , three-particle asymmetric cumulant , and the normalized cumulants and from the transverse momentum conservation and flow are calculated. The interplay between the two effects is also investigated. Our results are in a good agreement with the recent ATLAS measurements of multiparticle azimuthal correlations with the subevent cumulant method, which provides insight into the origin of collective flow in small systems.
{"title":"Symmetric cumulant sc2,4{4} and asymmetric cumulant ac2{3} from transverse momentum conservation and flow","authors":"Jia-Lin Pei (裴家琳), Guo-Liang Ma (马国亮), Adam Bzdak","doi":"10.1103/physrevc.110.024901","DOIUrl":"https://doi.org/10.1103/physrevc.110.024901","url":null,"abstract":"Multiparticle cumulants method can be used to reveal long-range collectivity in small and large colliding systems. The four-particle symmetric cumulant <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>s</mi><msub><mi>c</mi><mrow><mn>2</mn><mo>,</mo><mn>4</mn></mrow></msub><mrow><mo>{</mo><mn>4</mn><mo>}</mo></mrow></mrow></math>, three-particle asymmetric cumulant <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>a</mi><msub><mi>c</mi><mn>2</mn></msub><mrow><mo>{</mo><mn>3</mn><mo>}</mo></mrow></mrow></math>, and the normalized cumulants <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>n</mi><mi>s</mi><msub><mi>c</mi><mrow><mn>2</mn><mo>,</mo><mn>4</mn></mrow></msub><mrow><mo>{</mo><mn>4</mn><mo>}</mo></mrow></mrow></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>n</mi><mi>a</mi><msub><mi>c</mi><mn>2</mn></msub><mrow><mo>{</mo><mn>3</mn><mo>}</mo></mrow></mrow></math> from the transverse momentum conservation and flow are calculated. The interplay between the two effects is also investigated. Our results are in a good agreement with the recent ATLAS measurements of multiparticle azimuthal correlations with the subevent cumulant method, which provides insight into the origin of collective flow in small systems.","PeriodicalId":20122,"journal":{"name":"Physical Review C","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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