Pub Date : 2020-09-21DOI: 10.1103/PHYSREVC.103.024322
A. Zuker
[Background] The BE2 rates of the Sn isotopes for $Nle 64$ exhibit enhancements hitherto unexplained. The same is true for the Cd isotopes. [Purpose] Describe the electromagnetic properties of the Sn and Cd isotopes [Method] Shell model calculations with a minimally renormalized realistic interaction, supplemented by Quasi and Pseudo-SU3 symmetries and Nilsson-SU3 selfconsistent calculations. [Results for $Nle 64$] Shell model calculations with the neutron effective charge as single free parameter describe well the BE2(2>0) and BE2(4>2) rates for $Nle 64$ in the Cd and Sn isotopes. The former exhibit weak permanent deformation corroborating the prediction of a Pseudo-SU3 symmetry, which remains of heuristic value in the latter, where the pairing force erodes the quadrupole dominance. Calculations in $10^7$ and $10^{10}$-dimensional spaces exhibit almost identical patterns: A vindication of the shell model. [Results for $Nge 64$] Nilsson-SU3 calculations describe BE2 patterns in [112-120]Cd and [116-118]Sn isotopes having sizable quadrupole moment of non-rotational origin denoted as q-vibrations. No calculations are proposed for the heavier species, for which the conventional seniority dscription is assumed for Sn, while in Cd the quadrupole moments change sign. [Conclusion] A radical reexamination of traditional interpretations in the region has been shown to be necessary, in which quadrupole dominance plays a major role. What emerges is a bumpy but coherent view.
{"title":"Quadrupole dominance in the light Sn and in the Cd isotopes","authors":"A. Zuker","doi":"10.1103/PHYSREVC.103.024322","DOIUrl":"https://doi.org/10.1103/PHYSREVC.103.024322","url":null,"abstract":"[Background] The BE2 rates of the Sn isotopes for $Nle 64$ exhibit enhancements hitherto unexplained. The same is true for the Cd isotopes. [Purpose] Describe the electromagnetic properties of the Sn and Cd isotopes [Method] Shell model calculations with a minimally renormalized realistic interaction, supplemented by Quasi and Pseudo-SU3 symmetries and Nilsson-SU3 selfconsistent calculations. [Results for $Nle 64$] Shell model calculations with the neutron effective charge as single free parameter describe well the BE2(2>0) and BE2(4>2) rates for $Nle 64$ in the Cd and Sn isotopes. The former exhibit weak permanent deformation corroborating the prediction of a Pseudo-SU3 symmetry, which remains of heuristic value in the latter, where the pairing force erodes the quadrupole dominance. Calculations in $10^7$ and $10^{10}$-dimensional spaces exhibit almost identical patterns: A vindication of the shell model. [Results for $Nge 64$] Nilsson-SU3 calculations describe BE2 patterns in [112-120]Cd and [116-118]Sn isotopes having sizable quadrupole moment of non-rotational origin denoted as q-vibrations. No calculations are proposed for the heavier species, for which the conventional seniority dscription is assumed for Sn, while in Cd the quadrupole moments change sign. [Conclusion] A radical reexamination of traditional interpretations in the region has been shown to be necessary, in which quadrupole dominance plays a major role. What emerges is a bumpy but coherent view.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91344561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-18DOI: 10.1103/physrevc.102.064303
X. Roca-Maza, H. Sagawa, G. Colò
A formula to evaluate the effects of a general deformation on the Coulomb direct contribution to the energy of the Isobaric Analog State (IAS) is presented and studied via a simple yet physical model. The toy model gives a reasonable account of microscopic deformed Hartree-Fock-Bogolyubov (HFB) calculations in a test case, and provides a guidance when predicting unknown IAS energies. Thus, deformed HFB calculations, to predict the IAS energies, are performed for several neutron-deficient medium-mass and heavy nuclei which are now planned to be studied experimentally.
{"title":"Isobaric analog state energy in deformed nuclei: A toy model","authors":"X. Roca-Maza, H. Sagawa, G. Colò","doi":"10.1103/physrevc.102.064303","DOIUrl":"https://doi.org/10.1103/physrevc.102.064303","url":null,"abstract":"A formula to evaluate the effects of a general deformation on the Coulomb direct contribution to the energy of the Isobaric Analog State (IAS) is presented and studied via a simple yet physical model. The toy model gives a reasonable account of microscopic deformed Hartree-Fock-Bogolyubov (HFB) calculations in a test case, and provides a guidance when predicting unknown IAS energies. Thus, deformed HFB calculations, to predict the IAS energies, are performed for several neutron-deficient medium-mass and heavy nuclei which are now planned to be studied experimentally.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82437892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-17DOI: 10.1088/1361-6471/abcb58
Samuel B. Emmons, C. Ji, L. Platter
We calculate the longitudinal structure function of the deuteron up through next-to-next-to-leading order in the framework of pionless effective field theory. We use these results to compute the two-photon polarizability contribution to Lamb shift in muonic deuterium, which can be utilized to extract the nuclear charge radius of the deuteron. We present analytical expressions order-by-order for the relevant transition matrix elements and the longitudinal structure function, and we give numerical results for the corresponding contributions to the Lamb shift. We also discuss the impact of relativistic and other higher-order effects. We find agreement with previous calculations and explain the accuracy of our calculation.
{"title":"Pionless effective field theory evaluation of nuclear polarizability in muonic deuterium","authors":"Samuel B. Emmons, C. Ji, L. Platter","doi":"10.1088/1361-6471/abcb58","DOIUrl":"https://doi.org/10.1088/1361-6471/abcb58","url":null,"abstract":"We calculate the longitudinal structure function of the deuteron up through next-to-next-to-leading order in the framework of pionless effective field theory. We use these results to compute the two-photon polarizability contribution to Lamb shift in muonic deuterium, which can be utilized to extract the nuclear charge radius of the deuteron. We present analytical expressions order-by-order for the relevant transition matrix elements and the longitudinal structure function, and we give numerical results for the corresponding contributions to the Lamb shift. We also discuss the impact of relativistic and other higher-order effects. We find agreement with previous calculations and explain the accuracy of our calculation.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74800563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-14DOI: 10.1103/PhysRevResearch.2.033409
J. Hoelck, G. Wolschin
We reconsider baryon stopping in relativistic heavy-ion collisions in a nonequilibrium-statistical framework. The approach combines earlier formulations based on quantum chromodynamics with a relativistic diffusion model through a suitably derived fluctuation-dissipation relation, thus allowing for a fully time-dependent theory that is consistent with QCD. We use an existing framework for relativistic stochastic processes in spacetime that are Markovian in phase space, and adapt it to derive a Fokker-Planck equation in rapidity space, which is solved numerically. The time evolution of the net-proton distribution function in rapidity space agrees with stopping data from the CERN Super Proton Synchrotron and the BNL Relativistic Heavy Ion Collider.
{"title":"Baryon stopping as a relativistic Markov process in phase space","authors":"J. Hoelck, G. Wolschin","doi":"10.1103/PhysRevResearch.2.033409","DOIUrl":"https://doi.org/10.1103/PhysRevResearch.2.033409","url":null,"abstract":"We reconsider baryon stopping in relativistic heavy-ion collisions in a nonequilibrium-statistical framework. The approach combines earlier formulations based on quantum chromodynamics with a relativistic diffusion model through a suitably derived fluctuation-dissipation relation, thus allowing for a fully time-dependent theory that is consistent with QCD. We use an existing framework for relativistic stochastic processes in spacetime that are Markovian in phase space, and adapt it to derive a Fokker-Planck equation in rapidity space, which is solved numerically. The time evolution of the net-proton distribution function in rapidity space agrees with stopping data from the CERN Super Proton Synchrotron and the BNL Relativistic Heavy Ion Collider.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86437405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-14DOI: 10.1103/PHYSREVC.103.045808
C. Drischler, Sophia Han, J. Lattimer, M. Prakash, S. Reddy, Tianqi Zhao
We combine equation of state of dense matter up to twice nuclear saturation density ($n_{rm sat}=0.16, text{fm}^{-3}$) obtained using chiral effective field theory ($chi$EFT), and recent observations of neutron stars to gain insights about the high-density matter encountered in their cores. A key element in our study is the recent Bayesian analysis of correlated EFT truncation errors based on order-by-order calculations up to next-to-next-to-next-to-leading order in the $chi$EFT expansion. We refine the bounds on the maximum mass imposed by causality at high densities, and provide stringent limits on the maximum and minimum radii of $sim1.4,{rm M}_{odot}$ and $sim2.0,{rm M}_{odot}$ stars. Including $chi$EFT predictions from $n_{rm sat}$ to $2,n_{rm sat}$ reduces the permitted ranges of the radius of a $1.4,{rm M}_{odot}$ star, $R_{1.4}$, by $sim3.5, text{km}$. If observations indicate $R_{1.4} 1/2$ for densities above $2,n_{rm sat}$, or that $chi$EFT breaks down below $2,n_{rm sat}$. We also comment on the nature of the secondary compact object in GW190814 with mass $simeq 2.6,{rm M}_{odot}$, and discuss the implications of massive neutron stars $>2.1 ,{rm M}_{odot},(2.6,{rm M}_{odot})$ in future radio and gravitational-wave searches. Some form of strongly interacting matter with $c^2_{s}>0.35, (0.55)$ must be realized in the cores of such massive neutron stars. In the absence of phase transitions below $2,n_{rm sat}$, the small tidal deformability inferred from GW170817 lends support for the relatively small pressure predicted by $chi$EFT for the baryon density $n_{rm B}$ in the range $1-2,n_{rm sat}$. Together they imply that the rapid stiffening required to support a high maximum mass should occur only when $n_{rm B} gtrsim 1.5-1.8,n_{rm sat}$.
{"title":"Limiting masses and radii of neutron stars and their implications","authors":"C. Drischler, Sophia Han, J. Lattimer, M. Prakash, S. Reddy, Tianqi Zhao","doi":"10.1103/PHYSREVC.103.045808","DOIUrl":"https://doi.org/10.1103/PHYSREVC.103.045808","url":null,"abstract":"We combine equation of state of dense matter up to twice nuclear saturation density ($n_{rm sat}=0.16, text{fm}^{-3}$) obtained using chiral effective field theory ($chi$EFT), and recent observations of neutron stars to gain insights about the high-density matter encountered in their cores. A key element in our study is the recent Bayesian analysis of correlated EFT truncation errors based on order-by-order calculations up to next-to-next-to-next-to-leading order in the $chi$EFT expansion. We refine the bounds on the maximum mass imposed by causality at high densities, and provide stringent limits on the maximum and minimum radii of $sim1.4,{rm M}_{odot}$ and $sim2.0,{rm M}_{odot}$ stars. Including $chi$EFT predictions from $n_{rm sat}$ to $2,n_{rm sat}$ reduces the permitted ranges of the radius of a $1.4,{rm M}_{odot}$ star, $R_{1.4}$, by $sim3.5, text{km}$. If observations indicate $R_{1.4} 1/2$ for densities above $2,n_{rm sat}$, or that $chi$EFT breaks down below $2,n_{rm sat}$. We also comment on the nature of the secondary compact object in GW190814 with mass $simeq 2.6,{rm M}_{odot}$, and discuss the implications of massive neutron stars $>2.1 ,{rm M}_{odot},(2.6,{rm M}_{odot})$ in future radio and gravitational-wave searches. Some form of strongly interacting matter with $c^2_{s}>0.35, (0.55)$ must be realized in the cores of such massive neutron stars. In the absence of phase transitions below $2,n_{rm sat}$, the small tidal deformability inferred from GW170817 lends support for the relatively small pressure predicted by $chi$EFT for the baryon density $n_{rm B}$ in the range $1-2,n_{rm sat}$. Together they imply that the rapid stiffening required to support a high maximum mass should occur only when $n_{rm B} gtrsim 1.5-1.8,n_{rm sat}$.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80490792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-14DOI: 10.1103/PHYSREVC.103.014905
Sukanya Mitra
A second order relativistic hydrodynamic theory has been derived using momentum dependent relaxation time in the relativistic transport equation. In order to do that, an iterative technique of gradient expansion approach, namely Chapman-Enskog (CE) expansion of the particle distribution function has been employed. The key findings of this work are, (i) momentum dependent relaxation time in collision term results in an extended Landau matching condition for the thermodynamic variables, (ii) the result from numerical solution of Boltzmann equation lies somewhere in between the two popular extreme limits : linear and quadratic ansatz, indicating a fractional power of momentum dependence in relaxation time to be appropriate, (ii) an equivalence has been established between the iterative gradient expansion method like CE and the well known moment approach like Grad's 14-moment method.
{"title":"Relativistic hydrodynamics with momentum-dependent relaxation time","authors":"Sukanya Mitra","doi":"10.1103/PHYSREVC.103.014905","DOIUrl":"https://doi.org/10.1103/PHYSREVC.103.014905","url":null,"abstract":"A second order relativistic hydrodynamic theory has been derived using momentum dependent relaxation time in the relativistic transport equation. In order to do that, an iterative technique of gradient expansion approach, namely Chapman-Enskog (CE) expansion of the particle distribution function has been employed. The key findings of this work are, (i) momentum dependent relaxation time in collision term results in an extended Landau matching condition for the thermodynamic variables, (ii) the result from numerical solution of Boltzmann equation lies somewhere in between the two popular extreme limits : linear and quadratic ansatz, indicating a fractional power of momentum dependence in relaxation time to be appropriate, (ii) an equivalence has been established between the iterative gradient expansion method like CE and the well known moment approach like Grad's 14-moment method.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77342433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-14DOI: 10.1103/physrevc.102.064308
B. Reed, Z. Jaffe, C. Horowitz, C. Sfienti
The present PREX-II and CREX experiments are measuring the rms radius of the weak charge density of $^{208}$Pb and $^{48}$Ca. We discuss the feasibility of a new parity violating electron scattering experiment to measure the surface thickness of the weak charge density of a heavy nucleus. Once PREX-II and CREX have constrained weak radii, an additional parity violating measurement at a momentum transfer near 0.76 fm$^{-1}$ for $^{208}$Pb or 1.28 fm$^{-1}$ for $^{48}$Ca can determine the surface thickness.
{"title":"Measuring the surface thickness of the weak charge density of nuclei","authors":"B. Reed, Z. Jaffe, C. Horowitz, C. Sfienti","doi":"10.1103/physrevc.102.064308","DOIUrl":"https://doi.org/10.1103/physrevc.102.064308","url":null,"abstract":"The present PREX-II and CREX experiments are measuring the rms radius of the weak charge density of $^{208}$Pb and $^{48}$Ca. We discuss the feasibility of a new parity violating electron scattering experiment to measure the surface thickness of the weak charge density of a heavy nucleus. Once PREX-II and CREX have constrained weak radii, an additional parity violating measurement at a momentum transfer near 0.76 fm$^{-1}$ for $^{208}$Pb or 1.28 fm$^{-1}$ for $^{48}$Ca can determine the surface thickness.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86783513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-13DOI: 10.1088/1361-6471/abcdf7
B. Qi, Hui Zhang, Shou-Yu Wang, Qi Bo Chen
The influence of triaxial deformation $gamma$ on the purely collective form of wobbling motion in even-even nuclei are discussed based on the triaxial rotor model. It is found that the harmonic approximation is realized well when $gamma=30^{circ}$ for the properties of energy spectra and electric quadrupole transition probabilities, while this approximation gets bad when $gamma$ deviates from $30^{circ}$. A recent data from Coulomb excitation experiment, namely $3_1^+$ and $2_2^+$ for the $^{110}$Ru are studied and might be suggested as the bandhead of the wobbling bands. In addition, two types of angular momentum geometries for wobbling motion, stemming from different $gamma$ values, are exhibited by azimuthal plots.
{"title":"Influence of triaxial deformation on wobbling motion in even–even nuclei","authors":"B. Qi, Hui Zhang, Shou-Yu Wang, Qi Bo Chen","doi":"10.1088/1361-6471/abcdf7","DOIUrl":"https://doi.org/10.1088/1361-6471/abcdf7","url":null,"abstract":"The influence of triaxial deformation $gamma$ on the purely collective form of wobbling motion in even-even nuclei are discussed based on the triaxial rotor model. It is found that the harmonic approximation is realized well when $gamma=30^{circ}$ for the properties of energy spectra and electric quadrupole transition probabilities, while this approximation gets bad when $gamma$ deviates from $30^{circ}$. A recent data from Coulomb excitation experiment, namely $3_1^+$ and $2_2^+$ for the $^{110}$Ru are studied and might be suggested as the bandhead of the wobbling bands. In addition, two types of angular momentum geometries for wobbling motion, stemming from different $gamma$ values, are exhibited by azimuthal plots.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77421489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-13DOI: 10.5506/APHYSPOLBSUPP.14.461
Rajeev Singh
We review the key steps of the relativistic fluid dynamics formalism with spin degrees of freedom initiated recently. We obtain equations of motion of the expansion of the system from the underlying definitions of quantum kinetic theory for the equilibrium phase space distribution functions. We investigate the dynamics of spin polarization of the system in the Bjorken hydrodynamical background.
{"title":"Hydrodynamics Formalism with Spin Dynamics","authors":"Rajeev Singh","doi":"10.5506/APHYSPOLBSUPP.14.461","DOIUrl":"https://doi.org/10.5506/APHYSPOLBSUPP.14.461","url":null,"abstract":"We review the key steps of the relativistic fluid dynamics formalism with spin degrees of freedom initiated recently. We obtain equations of motion of the expansion of the system from the underlying definitions of quantum kinetic theory for the equilibrium phase space distribution functions. We investigate the dynamics of spin polarization of the system in the Bjorken hydrodynamical background.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76262307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-10DOI: 10.1103/PHYSREVC.103.045803
R. Somasundaram, C. Drischler, I. Tews, J. Margueron
The nuclear symmetry energy is a key quantity in nuclear (astro)physics. It describes the isospin dependence of the nuclear equation of state (EOS), which is commonly assumed to be almost quadratic. In this work, we confront this standard quadratic expansion of the EOS with explicit asymmetric nuclear-matter calculations based on a set of commonly used Hamiltonians including two- and three-nucleon forces derived from chiral effective field theory. We study, in particular, the importance of non-quadratic contributions to the symmetry energy, including the non-analytic logarithmic term introduced by Kaiser [Phys.~Rev.~C textbf{91}, 065201 (2015)]. Our results suggest that the quartic contribution to the symmetry energy can be robustly determined from the various Hamiltonians employed, and we obtain 1.00(8) MeV (or 0.55(8) MeV for the potential part) at saturation density, while the logarithmic contribution to the symmetry energy is relatively small and model-dependent. We finally employ the meta-model approach to study the impact of the higher-order contributions on the neutron-star crust-core transition density, and find a small 5% correction.
{"title":"Constraints on the nuclear symmetry energy from asymmetric-matter calculations with chiral \u0000NN\u0000 and \u00003N\u0000 interactions","authors":"R. Somasundaram, C. Drischler, I. Tews, J. Margueron","doi":"10.1103/PHYSREVC.103.045803","DOIUrl":"https://doi.org/10.1103/PHYSREVC.103.045803","url":null,"abstract":"The nuclear symmetry energy is a key quantity in nuclear (astro)physics. It describes the isospin dependence of the nuclear equation of state (EOS), which is commonly assumed to be almost quadratic. In this work, we confront this standard quadratic expansion of the EOS with explicit asymmetric nuclear-matter calculations based on a set of commonly used Hamiltonians including two- and three-nucleon forces derived from chiral effective field theory. We study, in particular, the importance of non-quadratic contributions to the symmetry energy, including the non-analytic logarithmic term introduced by Kaiser [Phys.~Rev.~C textbf{91}, 065201 (2015)]. Our results suggest that the quartic contribution to the symmetry energy can be robustly determined from the various Hamiltonians employed, and we obtain 1.00(8) MeV (or 0.55(8) MeV for the potential part) at saturation density, while the logarithmic contribution to the symmetry energy is relatively small and model-dependent. We finally employ the meta-model approach to study the impact of the higher-order contributions on the neutron-star crust-core transition density, and find a small 5% correction.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87853175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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