We present a simple description of pion-nucleon ($pi N$) scattering taking into account the full complexity of pion absorption and creation on the nucleon. To do this we solve Dyson-Schwinger equations within the framework of Time-Ordered Perturbation Theory. This enables us to construct partial wave separable $ pi N$ t matrices that can be useful in models of nuclear processes involving fully dressed nucleons. At the same time, our approach demonstrates features of Quantum Field Theory, like particle dressing, renormalisation, and the use of Dyson-Schwinger equations, in a non-relativistic context that is maximally close to that of Quantum Mechanics. For this reason, this article may also be of pedagogical interest.
考虑到介子在核子上的吸收和产生的全部复杂性，我们给出了介子-核子($pi N$)散射的简单描述。为此，我们在时间序摄动理论的框架内求解Dyson-Schwinger方程。这使我们能够构造部分波可分离的$ pi N$ t矩阵，这在涉及完全修饰核子的核过程模型中是有用的。同时，我们的方法展示了量子场论的特征，如粒子修饰、重整化和戴森-施温格方程的使用，在非相对论的背景下，最大程度地接近量子力学。出于这个原因，这篇文章也可能具有教学意义。
{"title":"Dyson–Schwinger approach to pion–nucleon scattering using time-ordered perturbation theory","authors":"B. Blankleider, J. Wray, A. Kvinikhidze","doi":"10.1063/5.0034753","DOIUrl":"https://doi.org/10.1063/5.0034753","url":null,"abstract":"We present a simple description of pion-nucleon ($pi N$) scattering taking into account the full complexity of pion absorption and creation on the nucleon. To do this we solve Dyson-Schwinger equations within the framework of Time-Ordered Perturbation Theory. This enables us to construct partial wave separable $ pi N$ t matrices that can be useful in models of nuclear processes involving fully dressed nucleons. At the same time, our approach demonstrates features of Quantum Field Theory, like particle dressing, renormalisation, and the use of Dyson-Schwinger equations, in a non-relativistic context that is maximally close to that of Quantum Mechanics. For this reason, this article may also be of pedagogical interest.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78664038","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 : 2020-10-20DOI: 10.1103/physrevc.102.054601
W. Horiuchi, Y. Suzuki, T. Uesaka, M. Miwa
Background: Eclipse effect of the neutron and proton in a deuteron target is essential to correctly describe high-energy deuteron scattering. The nucleus-deuteron scattering needs information not only on the nucleus-proton but also the nucleus-neutron interaction, for which no direct measurement of the nucleus-neutron cross sections is available for unstable nuclei. Purpose: We systematically evaluated the total reaction cross sections by a deuteron target to explore the feasibility of extracting the nucleus-neutron interaction from measurable cross sections. Methods: High-energy nucleus-deuteron collision is described by the Glauber model, in which the proton and neutron configuration of the deuteron is explicitly taken into account. Results: Our calculation reproduces available experimental total reaction cross section data on the nucleus-deuteron scattering. The possibility of extracting the nucleus-neutron total reaction cross section from nucleus-deuteron and nucleus-proton total reaction cross sections is explored. The total reaction cross sections of a nucleus by proton, neutron, and deuteron targets can be expressed, to good accuracy, in terms of the nuclear matter radius and neutron skin thickness. Incident-energy dependence of the total reaction cross sections is examined. Conclusions: The total reaction cross section on a deuteron target includes information on both the nucleus-neutron and nucleus-proton profile functions. Measuring the cross sections by deuteron and proton targets is a promising tool to extract the nuclear size properties.
{"title":"Total reaction cross section on a deuteron target and the eclipse effect of the constituent neutron and proton","authors":"W. Horiuchi, Y. Suzuki, T. Uesaka, M. Miwa","doi":"10.1103/physrevc.102.054601","DOIUrl":"https://doi.org/10.1103/physrevc.102.054601","url":null,"abstract":"Background: Eclipse effect of the neutron and proton in a deuteron target is essential to correctly describe high-energy deuteron scattering. The nucleus-deuteron scattering needs information not only on the nucleus-proton but also the nucleus-neutron interaction, for which no direct measurement of the nucleus-neutron cross sections is available for unstable nuclei. \u0000Purpose: We systematically evaluated the total reaction cross sections by a deuteron target to explore the feasibility of extracting the nucleus-neutron interaction from measurable cross sections. \u0000Methods: High-energy nucleus-deuteron collision is described by the Glauber model, in which the proton and neutron configuration of the deuteron is explicitly taken into account. \u0000Results: Our calculation reproduces available experimental total reaction cross section data on the nucleus-deuteron scattering. The possibility of extracting the nucleus-neutron total reaction cross section from nucleus-deuteron and nucleus-proton total reaction cross sections is explored. The total reaction cross sections of a nucleus by proton, neutron, and deuteron targets can be expressed, to good accuracy, in terms of the nuclear matter radius and neutron skin thickness. Incident-energy dependence of the total reaction cross sections is examined. \u0000Conclusions: The total reaction cross section on a deuteron target includes information on both the nucleus-neutron and nucleus-proton profile functions. Measuring the cross sections by deuteron and proton targets is a promising tool to extract the nuclear size properties.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83262261","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 : 2020-10-20DOI: 10.1103/PhysRevC.103.064610
P. Ducru, A. Alhajri, I. Meyer, B. Forget, V. Sobes, C. Josey, Jin'gang Liang
Nuclear cross sections are basic inputs to any nuclear computation. Campaigns of experiments are fitted with the parametric R-matrix model of quantum nuclear interactions, and the resulting cross sections are documented - both point-wise and as resonance parameters (with uncertainties) - in standard evaluated nuclear data libraries (ENDF, JEFF, BROND, JENDL, CENDL, TENDL): these constitute our common knowledge of fundamental nuclear physics. In the past decade, a collaborative effort has been deployed to establish a new nuclear cross section library format - the Windowed Multipole Library - with the goal of considerably reducing the cost of cross section calculations in nuclear transport simulations. This article lays the theoretical foundations underpinning these efforts. From general R-matrix scattering theory, we derive the windowed multipole representation of nuclear cross sections. Though physically and mathematically equivalent, the windowed multipole representation is particularly well suited for subsequent temperature treatment of angle-integrated cross sections: we show that accurate Doppler broadening can be performed analytically up to the first reaction threshold; and we derive cross sections temperature derivatives to any order. Furthermore, we here establish a way of converting the R-matrix resonance parameters uncertainty (covariance matrices) into windowed multipole parameters uncertainty. We show that generating stochastic nuclear cross sections by sampling from the resulting windowed multipole covariance matrix can reproduce the cross section uncertainty in the original nuclear data file. Through this foundational article, we hope to make the Windowed Multipole Representation accessible, reproducible, and usable for the nuclear physics community, as well as provide the theoretical basis for future research on expanding its capabilities.
{"title":"Windowed multipole representation of \u0000R\u0000-matrix cross sections","authors":"P. Ducru, A. Alhajri, I. Meyer, B. Forget, V. Sobes, C. Josey, Jin'gang Liang","doi":"10.1103/PhysRevC.103.064610","DOIUrl":"https://doi.org/10.1103/PhysRevC.103.064610","url":null,"abstract":"Nuclear cross sections are basic inputs to any nuclear computation. Campaigns of experiments are fitted with the parametric R-matrix model of quantum nuclear interactions, and the resulting cross sections are documented - both point-wise and as resonance parameters (with uncertainties) - in standard evaluated nuclear data libraries (ENDF, JEFF, BROND, JENDL, CENDL, TENDL): these constitute our common knowledge of fundamental nuclear physics. In the past decade, a collaborative effort has been deployed to establish a new nuclear cross section library format - the Windowed Multipole Library - with the goal of considerably reducing the cost of cross section calculations in nuclear transport simulations. This article lays the theoretical foundations underpinning these efforts. From general R-matrix scattering theory, we derive the windowed multipole representation of nuclear cross sections. Though physically and mathematically equivalent, the windowed multipole representation is particularly well suited for subsequent temperature treatment of angle-integrated cross sections: we show that accurate Doppler broadening can be performed analytically up to the first reaction threshold; and we derive cross sections temperature derivatives to any order. Furthermore, we here establish a way of converting the R-matrix resonance parameters uncertainty (covariance matrices) into windowed multipole parameters uncertainty. We show that generating stochastic nuclear cross sections by sampling from the resulting windowed multipole covariance matrix can reproduce the cross section uncertainty in the original nuclear data file. Through this foundational article, we hope to make the Windowed Multipole Representation accessible, reproducible, and usable for the nuclear physics community, as well as provide the theoretical basis for future research on expanding its capabilities.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76248103","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 : 2020-10-17DOI: 10.1088/1361-6471/abe104
V. Dexheimer, J. Noronha, J. Noronha-Hostler, N. Yunes, C. Ratti
With the computational power and algorithmic improvements available today, the ongoing STAR/RHIC and HADES/GSI experiments, the future FAIR and NICA facilities becoming operational, and the new precise measurements from NICER and LIGO/VIRGO, the high-energy nuclear physics and astrophysics communities are in the unique position to set very stringent constraints on the equation of state of strongly interacting matter. We review the state-of-the-art of different approaches used in the description of hot and ultradense baryonic matter in and out of equilibrium, and discuss the regions in the phase diagram where heavy-ion collisions and neutron star mergers can overlap. Future perspectives are discussed to help define a comprehensive, multi-disciplinary strategy to map out the phase diagram of strongly interacting matter from heavy ion collisions to neutron stars.
{"title":"Future Physics Perspectives on the Equation of State from Heavy Ion Collisions to Neutron Stars","authors":"V. Dexheimer, J. Noronha, J. Noronha-Hostler, N. Yunes, C. Ratti","doi":"10.1088/1361-6471/abe104","DOIUrl":"https://doi.org/10.1088/1361-6471/abe104","url":null,"abstract":"With the computational power and algorithmic improvements available today, the ongoing STAR/RHIC and HADES/GSI experiments, the future FAIR and NICA facilities becoming operational, and the new precise measurements from NICER and LIGO/VIRGO, the high-energy nuclear physics and astrophysics communities are in the unique position to set very stringent constraints on the equation of state of strongly interacting matter. We review the state-of-the-art of different approaches used in the description of hot and ultradense baryonic matter in and out of equilibrium, and discuss the regions in the phase diagram where heavy-ion collisions and neutron star mergers can overlap. Future perspectives are discussed to help define a comprehensive, multi-disciplinary strategy to map out the phase diagram of strongly interacting matter from heavy ion collisions to neutron stars.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73265516","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}
Background: The triaxial and hexadecapole deformations of the K=0+ and K=2+ bands of 24Mg have been investigated by the inelastic scatterings of various probes, including electrons, protons, and alpha particles, for a prolonged time. However, it has been challenging to explain the unique properties of the scatterings observed for the $4^+_1$ state through reaction calculations. Purpose: To investigate the structure and transition properties of the K=0+ and K=2+ bands of 24Mg employing the microscopic structure and reaction calculations via inelastic proton and alpha-scattering. Particularly, the E4 transitions to the $4^+_1$ and $4^+_2$ states were reexamined. Method: The structure of 24Mg was calculated employing the variation after the parity and total-angular momentum projections in the framework of the antisymmetrized molecular dynamics(AMD). The inelastic proton and alpha reactions were calculated by the microscopic coupled-channel (MCC) approach by folding the Melbourne g-matrix NN interaction with the AMD densities of 24Mg. Results: Reasonable results were obtained on the properties of the structure, including the energy spectra and E2 and E4 transitions of the K=0+ and K=2+ bands owing to the enhanced collectivity of triaxial deformation. The MCC+AMD calculation successfully reproduced the angular distributions of the $4^+_1$ and $4^+_2$ cross sections of proton scattering at incident energies of $E_p$=40--100MeV and alpha-scattering at $E_alpha$=100--400MeV. Conclusions: This is the first microscopic calculation that described the unique properties of the $0^+_1to 4^+_1$ transition. In the inelastic scattering to the $4^+_1$ state, the dominant two-step process of the $0^+_1to 2^+_1to 4^+_1$ transitions and the deconstructive interference is the weak one-step process were essential.
{"title":"Microscopic coupled-channel calculation of proton and alpha inelastic scattering to the $4^+_1$ and $4^+_2$ states of $^{24}textrm{Mg}$","authors":"Y. Kanada-En’yo, K. Ogata","doi":"10.1093/PTEP/PTAB029","DOIUrl":"https://doi.org/10.1093/PTEP/PTAB029","url":null,"abstract":"Background: The triaxial and hexadecapole deformations of the K=0+ and K=2+ bands of 24Mg have been investigated by the inelastic scatterings of various probes, including electrons, protons, and alpha particles, for a prolonged time. However, it has been challenging to explain the unique properties of the scatterings observed for the $4^+_1$ state through reaction calculations. Purpose: To investigate the structure and transition properties of the K=0+ and K=2+ bands of 24Mg employing the microscopic structure and reaction calculations via inelastic proton and alpha-scattering. Particularly, the E4 transitions to the $4^+_1$ and $4^+_2$ states were reexamined. Method: The structure of 24Mg was calculated employing the variation after the parity and total-angular momentum projections in the framework of the antisymmetrized molecular dynamics(AMD). The inelastic proton and alpha reactions were calculated by the microscopic coupled-channel (MCC) approach by folding the Melbourne g-matrix NN interaction with the AMD densities of 24Mg. Results: Reasonable results were obtained on the properties of the structure, including the energy spectra and E2 and E4 transitions of the K=0+ and K=2+ bands owing to the enhanced collectivity of triaxial deformation. The MCC+AMD calculation successfully reproduced the angular distributions of the $4^+_1$ and $4^+_2$ cross sections of proton scattering at incident energies of $E_p$=40--100MeV and alpha-scattering at $E_alpha$=100--400MeV. Conclusions: This is the first microscopic calculation that described the unique properties of the $0^+_1to 4^+_1$ transition. In the inelastic scattering to the $4^+_1$ state, the dominant two-step process of the $0^+_1to 2^+_1to 4^+_1$ transitions and the deconstructive interference is the weak one-step process were essential.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74625560","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 : 2020-10-13DOI: 10.1103/PhysRevC.103.054320
P. Bączyk, W. Satula
Background: Small asymmetry between neutrons and protons, caused by the differences in masses and charges of the up and down constituent quarks leads to the isospin symmetry breaking. The isospin non-conservation affects broad range of observables from superallowed Fermi weak interaction to isospin-forbidden electromagnetic rates. Its most profound and cleanest manifestation are systematic shifts in masses and excitation energies of mirror atomic nuclei. Purpose: Recently, we constructed the charge-dependent DFT that includes class II and III local interactions and demonstrated that the model allows for very accurate reproduction of Mirror and Triplet Displacement energies in a very broad range of masses. The aim of this work is to further test the charge-dependent functional by studying Mirror Energy Differences (MEDs) in function of angular momentum $I$. Methods: To compute MEDs we use DFT-rooted no core configuration interaction model. This post mean-field method restores rotational symmetry and takes into account configuration mixing within a space that includes relevant (multi)particle-(multi)hole Slater determinants. Results: We applied the model to $f_{7/2}$-shell mirror pairs of $A=43$, $45$, $47$, and $49$ focusing on MEDs in low-spin part (below band crossing) what allowed us to limit the model space to seniority one and three (one broken pair) configurations. Conclusions: We demonstrate that, for spins $Ileq 15/2$ being subject of the present study, our model reproduces well experimental MEDs which vary strongly in function of $I$ and $A$. The quality of model's predictions is comparable to the nuclear shell-model results by Bentley et al. Phys. Rev. C 92, 024310 (2015).
背景:由上下夸克的质量和电荷差异引起的中子和质子之间的微小不对称导致了同位旋对称性的破坏。同位旋不守恒影响了从超允许费米弱相互作用到禁止同位旋电磁速率的广泛观测值。它最深刻和最清晰的表现是镜像原子核的质量和激发能的系统变化。目的:最近，我们构建了包含II类和III类局部相互作用的电荷依赖DFT，并证明了该模型允许在非常广泛的质量范围内非常精确地再现镜像和三重态位移能量。本工作的目的是通过研究镜像能差(med)在角动量函数$I$中的作用来进一步测试电荷依赖泛函。方法:采用基于dft的无核心组态交互模型计算med。该post平均场方法恢复了旋转对称性，并考虑了包含相关(多)粒子-(多)孔Slater决定因素的空间内的配置混合。结果:我们将模型应用于$A=43$, $45$, $47$和$49$的$f_{7/2}$ -壳镜像对，重点关注低自旋部分(低于带交叉)的med，这使我们能够将模型空间限制为优先1和3(一个破碎对)配置。结论:我们证明，对于$Ileq 15/2$作为本研究的主题，我们的模型很好地再现了$I$和$A$功能强烈变化的实验med。模型的预测质量可与Bentley等人的核壳模型结果相媲美。物理。Rev. C 92, 024310(2015)。
{"title":"Mirror energy differences in \u0000T=1/2f7/2\u0000-shell nuclei within isospin-dependent density functional theory","authors":"P. Bączyk, W. Satula","doi":"10.1103/PhysRevC.103.054320","DOIUrl":"https://doi.org/10.1103/PhysRevC.103.054320","url":null,"abstract":"Background: Small asymmetry between neutrons and protons, caused by the differences in masses and charges of the up and down constituent quarks leads to the isospin symmetry breaking. The isospin non-conservation affects broad range of observables from superallowed Fermi weak interaction to isospin-forbidden electromagnetic rates. Its most profound and cleanest manifestation are systematic shifts in masses and excitation energies of mirror atomic nuclei. \u0000Purpose: Recently, we constructed the charge-dependent DFT that includes class II and III local interactions and demonstrated that the model allows for very accurate reproduction of Mirror and Triplet Displacement energies in a very broad range of masses. The aim of this work is to further test the charge-dependent functional by studying Mirror Energy Differences (MEDs) in function of angular momentum $I$. \u0000Methods: To compute MEDs we use DFT-rooted no core configuration interaction model. This post mean-field method restores rotational symmetry and takes into account configuration mixing within a space that includes relevant (multi)particle-(multi)hole Slater determinants. \u0000Results: We applied the model to $f_{7/2}$-shell mirror pairs of $A=43$, $45$, $47$, and $49$ focusing on MEDs in low-spin part (below band crossing) what allowed us to limit the model space to seniority one and three (one broken pair) configurations. \u0000Conclusions: We demonstrate that, for spins $Ileq 15/2$ being subject of the present study, our model reproduces well experimental MEDs which vary strongly in function of $I$ and $A$. The quality of model's predictions is comparable to the nuclear shell-model results by Bentley et al. Phys. Rev. C 92, 024310 (2015).","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84347087","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 : 2020-10-13DOI: 10.1103/PHYSREVA.103.023333
J. Qin, Jared Vanasse
Cold Helium atoms are a unique system where a single excited three-body Efimov state occurs, naturally, without the need for an external magnetic field. While three-body bound state energies of cold Helium atoms have previously been investigated, recent experimental techniques have allowed their structure to also be studied. The weak interaction between Helium atoms leads to a helium-helium (dimer) scattering length, $a$, much larger than the helium-helium effective range of interaction, $r$. This feature is exploited in a theory that systematically expands observables in powers of $r/a$, known as short range effective field theory (srEFT), which has been used successfully to investigate properties of cold atom systems. Using srEFT we investigate the average bond length of atoms in the three-body ground state and excited Efimov state of cold Helium atoms. At leading-order (next-to-leading order) in srEFT, we find the average bond length of the $^4$He trimer ground state is 8.35(33) A (10.29(2) A) and the average bond length of the excited $^4$He trimer Efimov state is 103(4) A (105.3(2) A).
{"title":"Effective-field-theory analysis of boson-trimer bond lengths to next-to-leading order","authors":"J. Qin, Jared Vanasse","doi":"10.1103/PHYSREVA.103.023333","DOIUrl":"https://doi.org/10.1103/PHYSREVA.103.023333","url":null,"abstract":"Cold Helium atoms are a unique system where a single excited three-body Efimov state occurs, naturally, without the need for an external magnetic field. While three-body bound state energies of cold Helium atoms have previously been investigated, recent experimental techniques have allowed their structure to also be studied. The weak interaction between Helium atoms leads to a helium-helium (dimer) scattering length, $a$, much larger than the helium-helium effective range of interaction, $r$. This feature is exploited in a theory that systematically expands observables in powers of $r/a$, known as short range effective field theory (srEFT), which has been used successfully to investigate properties of cold atom systems. Using srEFT we investigate the average bond length of atoms in the three-body ground state and excited Efimov state of cold Helium atoms. At leading-order (next-to-leading order) in srEFT, we find the average bond length of the $^4$He trimer ground state is 8.35(33) A (10.29(2) A) and the average bond length of the excited $^4$He trimer Efimov state is 103(4) A (105.3(2) A).","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80102396","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 : 2020-10-12DOI: 10.1103/physrevd.102.103003
Márcio Ferreira, C. Providencia
We analyze how the crust equation of state affects several neutron star properties and how it impacts on possible constraints inferred from astrophysical observations. Using three distinct crusts, we generate three sets of model-independent equations of state describing stellar matter from a Taylor expansion around saturation density. The equations of state are thermodynamically consistent, causal, and compatible with astrophysical observations. The relations between the tidal deformability $Lambda$ and compactness $C$, Love number $k_2$ and radius of neutron star with mass $M$ are studied, and the effect of the crust equation of state on these relations analyzed. In most of the relations, the impact of the crust equation of state is not larger that 2%. If, however, a fixed neutron star mass is considered, the relation between the tidal deformability and the radius depends on the crust. We have found that the relation $Lambda_{M_i} = alpha R_{M_i}^{beta}$ becomes almost exact and crust independent for massive neutron stars. It is shown that it is possible to determine the tidal deformability of an 1.4$M_odot$ star from the GW179817 effective tidal deformability $tildeLambda$ with an accuracy of at least $approx 10%$. A high correlation between $tildeLambda$ and the radius of the most massive star of the neutron star binary was confirmed, however, it was demonstrated that the crust has an effect of $approx 14%$ on this relation. We have found that the relation $Lambda_1/Lambda_2=q^a$ depends on $M_{text{chirp}}$ as $asim sqrt{M_{text{chirp}}}$.
{"title":"Effect of the crust on neutron star empirical relations","authors":"Márcio Ferreira, C. Providencia","doi":"10.1103/physrevd.102.103003","DOIUrl":"https://doi.org/10.1103/physrevd.102.103003","url":null,"abstract":"We analyze how the crust equation of state affects several neutron star properties and how it impacts on possible constraints inferred from astrophysical observations. Using three distinct crusts, we generate three sets of model-independent equations of state describing stellar matter from a Taylor expansion around saturation density. The equations of state are thermodynamically consistent, causal, and compatible with astrophysical observations. The relations between the tidal deformability $Lambda$ and compactness $C$, Love number $k_2$ and radius of neutron star with mass $M$ are studied, and the effect of the crust equation of state on these relations analyzed. In most of the relations, the impact of the crust equation of state is not larger that 2%. If, however, a fixed neutron star mass is considered, the relation between the tidal deformability and the radius depends on the crust. We have found that the relation $Lambda_{M_i} = alpha R_{M_i}^{beta}$ becomes almost exact and crust independent for massive neutron stars. It is shown that it is possible to determine the tidal deformability of an 1.4$M_odot$ star from the GW179817 effective tidal deformability $tildeLambda$ with an accuracy of at least $approx 10%$. A high correlation between $tildeLambda$ and the radius of the most massive star of the neutron star binary was confirmed, however, it was demonstrated that the crust has an effect of $approx 14%$ on this relation. We have found that the relation $Lambda_1/Lambda_2=q^a$ depends on $M_{text{chirp}}$ as $asim sqrt{M_{text{chirp}}}$.","PeriodicalId":8463,"journal":{"name":"arXiv: Nuclear Theory","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81738960","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 : 2020-10-10DOI: 10.1103/PhysRevC.103.055816
J. A. Rosero-Gil, G. Lugones
We study the weak interaction processes taking place within a combustion flame that converts dense hadronic matter into quark matter in a compact star. Using the Boltzmann equation we follow the evolution of a small element of just deconfined quark matter all along the flame interior until it reaches chemical equilibrium at the back boundary of the flame. We obtain the reaction rates and neutrino emissivities of all the relevant weak interaction processes without making any assumption about the neutrino degeneracy. We analyse systematically the role the initial conditions of unburnt hadronic matter, such as density, temperature, neutrino trapping and composition, focusing on typical astrophysical scenarios such as cold neutron stars, protoneutron stars, and post merger compact objects. We find that the temperature within the flame rises significantly in a timescale of 1 nanosecond. The increase in $T$ strongly depends on the initial strangeness of hadronic matter and tends to be more drastic at larger densities. Typical final values range between $20$ and $60 , mathrm{MeV}$. The nonleptonic process $u + d rightarrow u + s$ is always dominant in cold stars, but in hot object the process $u + e^{-} leftrightarrow d + {nu_e}$ becomes relevant, and in some cases dominant, near chemical equilibrium. The rates for the other processes are orders of magnitude smaller. We find that the neutrino emissivity per baryon is very large, leading to a total energy release per baryon of $2-64 , mathrm{MeV}$ in the form of neutrinos along the flame. We discuss some astrophysical consequences of the results.
我们研究了发生在燃烧火焰中将致密强子物质转化为致密恒星中夸克物质的弱相互作用过程。利用玻尔兹曼方程，我们沿着火焰内部跟踪刚定义的夸克物质的小元素的演化，直到它在火焰的后边界达到化学平衡。我们得到了所有相关弱相互作用过程的反应速率和中微子发射率，而不做任何关于中微子简并的假设。我们系统地分析了未燃烧强子物质的初始条件，如密度、温度、中微子俘获和组成，重点分析了典型的天体物理场景，如冷中子星、质子中子星和合并后致密天体。我们发现火焰内的温度在1纳秒的时间尺度内显著上升。$T$的增加很大程度上取决于强子物质的初始奇异性，并且在更大的密度下趋于更剧烈。典型的最终值范围在$20$和$60 , mathrm{MeV}$之间。非轻子过程$u + d rightarrow u + s$在冷的恒星中总是占主导地位，但在热的物体中，过程$u + e^{-} leftrightarrow d + {nu_e}$变得相关，在某些情况下，在化学平衡附近占主导地位。其他过程的速率要小几个数量级。我们发现每个重子的中微子发射率非常大，导致每个重子沿火焰以中微子形式释放的总能量为$2-64 , mathrm{MeV}$。我们讨论了这些结果的一些天体物理学后果。
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