Nuclear Theory·nucl-th

Thursday·September 24, 2020

12 papers—6 primary·6 cross-listed

01
[Submitted on 22 Sept 2020]
Relation between transition density and proton inelastic scattering by $^{12}$ C target at $E_{p} =$ 65 and 200 MeV
T. Furumoto🇯🇵 · M. Takashina🇯🇵
We calculate proton elastic and inelastic scatterings with a microscopic coupled channel (MCC) calculation. The localized diagonal and coupling potentials including the spin-orbit part are obtained by folding a complex $G$ -matrix effective nucleon-nucleon interaction with a transition density. This is the first time that the present folding prescription for the spin-orbit part is applied to the proton inelastic scattering, while for the monopole transition only. We apply the MCC calculation to the proton elastic and inelastic (0 $_{2}^{+}$ ) scatterings by $^{12}$ C target at $E_{p}$ = 65 and 200 MeV. The role of diagonal and coupling potentials for the central and spin-orbit parts is checked. In addition, the relation between the transition density and the proton inelastic scattering is investigated with the modified wave function and the modified transition density. Namely, we perform the investigation with the artificial drastic change rather than fine structural change. The inelastic cross section is sensitive to the strength and shape of the transition density, but the inelastic analyzing power is sensitive only to the shape of that. Finally, we make clear the property of the inelastic analyzing power derived from the transition density without an ambiguity.
Comments:
20 pages, 12 figures, accepted in Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2009.10841 [pdf]
PRC(2021)·4 citations
02
[Submitted on 22 Sept 2020]
Phenomenological quark-hadron equations of state with first-order phase transitions for astrophysical applications
Niels-Uwe F. Bastian🇵🇱
In the current work an equation of state model with a first-order phase transition for astrophysical applications is presented. The model is based on a two-phase approach for quark-hadron phase transitions, which leads by construction to a first-order phase transition. The resulting model has already been successfully used in several astrophysical applications, such as cold neutron stars, core-collapse supernova explosions and binary neutron star mergers. Main goal of this work is to present the details of the model, discuss certain features and eventually publish it in a tabulated form for further use.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2009.10846 [pdf]
PRD(2021)·50 citations
03
[Submitted on 22 Sept 2020]
Variational and parquet-diagram calculations for neutron matter. II. Twisted Chain Diagrams
E. Krotscheck · J. Wang
We develop a manifestly microscopic method to deal with strongly interacting nuclear systems that have different interactions in spin-singlet and spin-triplet states. In a first step we analyze variational wave functions that have been suggested to describe such systems, and demonstrate that the so-called commutator contributions can have important effects whenever the interactions in the spin-singlet and the spin-triplet states are very different. We then identify these contributions as terms that correspond, in the language of perturbation theory, to non-parquet diagrams. We include these diagrams in a way that is suggested by the Jastrow-Feenberg approach and show that the corrections from non-parquet contributions are, at short distances, larger than all other many-body effects.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.10849 [pdf]
PRC(2020)·8 citations
04
[Submitted on 23 Sept 2020]
On the Speed of Sound in Hyperonic Stars
T. F. Motta🇦🇺 · P. A. M. Guichon🇫🇷 · A. W. Thomas🇦🇺
We build upon the remarkable, model independent constraints on the equation of state of dense baryonic matter established recently by Annala et al. [1]. Using the quark-meson coupling model, an approach to nuclear structure based upon the self-consistent adjustment of hadron structure to the local meson fields, we show that, once hyperons are allowed to appear in dense matter in \b{eta}-equilibrium, the equation of state is consistent with those constraints. As a result, while one cannot rule out the occurence of quark matter in the cores of massive neutron stars, the available constraints are also compatible with the presence of hyperons.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2009.10908 [pdf]
NPA(2021)·30 citations
05
[Submitted on 22 Sept 2020]
Density-Dependent Neutron-Neutron Interaction from Subleading Chiral Three-Neutron Forces
Lukas Treuer🇩🇪
Three-nucleon forces are an essential ingredient for an accurate description of nuclear few- and many-body systems. However, implementing them directly in many-body calculations is technically very challenging. Thus, there is a need for an efficient approximation method. By closing one nucleon line to a loop, it is possible to derive effective in-medium nucleon-nucleon interactions that represent the underlying three-nucleon forces, as constructed in Chiral Effective Field Theory. Since three-neutron forces are equally as important for the computation of the equation of state for pure neutron matter, this work applies the aforementioned approach to the subleading chiral three-neutron forces, in particular the short-range terms and relativistic corrections. It is shown in this work that, while many contributions to the in-medium neutron-neutron interaction are - apart from a constant factor - identical to the terms in isospin-symmetric matter, some differ drastically. Moreover, previously vanishing terms yield now non-zero contributions. As a result of this work, density-dependent in-medium neutron-neutron potentials are now available for the implementation in nuclear many-body calculations, either in closed analytical form, or requiring at most one numerical integration.
Comments:
40 pages, 5 figures; Bachelor's thesis in physics, Technische Universität München, September 2020, supervised by Prof. Dr. Norbert Kaiser | The second version corrected the typing errors $(2 p^{2} - q^{2} /4) \to (2 p^{2} + q^{2} /4)$ in the ninth line of eq. (3.22), and $1/ f_{π}^{2} \to 1/ f_{π}^{4}$ in the coefficients of eq. (3.30) and eq. (3.32)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.11104 [pdf]
6 citations
06
[Submitted on 23 Sept 2020]
The Spin Orbit term in the Nuclear Shell Model
H. Müther
Quasi-nuclear systems, representing nuclei with variable size, are studied to investigate the occurrence of the spin-orbit term in the nuclear mean field in the transition from infinite nuclear matter to finite nuclei. Relativistic as well as non-relativistic mean field calculations based on models for the nucleon-nucleon ( $N N$ ) interaction, which fit the $N N$ scattering data, are considered. A very strong correlation between the strength of the spin-orbit term and radius of the nuclear system is observed. The origin of the spin-orbit term is analyzed by inspecting the contributions of the different partial waves and various mesons in a One-Boson-Exchange model of the $N N$ interaction. The influence of correlation effects and the enhancement of the small component of Dirac spinors for nucleons in the nuclear medium is discussed.
Comments:
13 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.11214 [pdf]
PRC(2021)·3 citations
07
[Submitted on 22 Sept 2020] (cross-list from astro-ph.HE)
Rapidly Spinning Compact Stars with Deconfinement Phase Transition
Tuna Demircik🇮🇱 · Christian Ecker🇩🇪 · Matti Järvinen🇮🇱
We study rapidly spinning compact stars with equations of state featuring a first order phase transition between strongly coupled nuclear matter and deconfined quark matter by employing the gauge/gravity duality. We consider a family of models, which allow purely hadronic uniformly rotating stars with masses up to approximately $2.9 M_{⊙}$ , and are therefore compatible with the interpretation that the secondary component ( $2.5 9_{- 0.09}^{+ 0.08} M_{⊙}$ ) in GW190814 is a neutron star. These stars have central densities several times the nuclear saturation density so that strong coupling and non-perturbative effects become crucial. We construct models where the maximal mass of static (rotating) stars $M_{TOV}$ ( $M_{max}$ ) is either determined by the secular instability or a phase transition induced collapse. We find largest values for $M_{max} / M_{TOV}$ in cases where the phase transition determines $M_{max}$ , which shifts our fit result to $M_{max} / M_{TOV} = 1.22 7_{- 0.016}^{+ 0.031}$ , a value slightly above the Breu-Rezzolla bound $1.20 3_{- 0.022}^{+ 0.022}$ inferred from models without phase transition.
Comments:
7 pages, 5 figures, comments welcome
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2009.10731 [pdf]
ApJL(2021)·55 citations
08
[Submitted on 22 Sept 2020] (cross-list from hep-th)
Evolution of Non-Gaussian Hydrodynamic Fluctuations
Xin An🇺🇸 · Gokce Basar🇺🇸 · Mikhail Stephanov🇺🇸 · Ho-Ung Yee🇺🇸
In the context of the search for the QCD critical point using non-Gaussian fluctuations, we obtain the evolution equations for non-Gaussian cumulants to the leading order of the systematic expansion in the magnitude of thermal fluctuations. We develop a diagrammatic technique in which the leading order contributions are given by tree diagrams. We introduce a Wigner transform for multipoint correlators and derive the evolution equations for three- and four-point Wigner functions for the problem of nonlinear stochastic diffusion with multiplicative noise.
Comments:
8 pages, 3 figures. Clarifications and Supplementary Material with a numerical simulation added. Version accepted by PRL
Subjects:
High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.10742 [pdf]
PRL(2021)·60 citations
09
[Submitted on 22 Sept 2020] (cross-list from hep-ph)
Repulsive properties of hadrons in lattice QCD data and neutron stars
Anton Motornenko🇩🇪 · Somenath Pal🇮🇳 · Abhijit Bhattacharyya🇮🇳 · Jan Steinheimer🇩🇪 · Horst Stoecker🇩🇪
Second-order susceptibilities $χ_{ij}^{11}$ of baryon, electric, and strangeness, $B$ , $Q$ , and $S$ , charges, are calculated in the Chiral Mean Field (CMF) model and compared to available lattice QCD data. The susceptibilities are sensitive to the short range repulsive interactions between different hadron species, especially to the hardcore repulsion of hyperons. Decreasing the hyperons size, as compared to the size of the non-strange baryons, does improve significantly the agreement of the CMF model results with the Lattice QCD data. The electric charge-dependent susceptibilities are sensitive to the short range repulsive volume of mesons. The comparison with lattice QCD data suggests that strange baryons, non-strange mesons and strange mesons have significantly smaller excluded volumes than non-strange baryons. The CMF model with these modified hadron volumes allows for a mainly hadronic description of the QCD susceptibilities significantly above the chiral pseudo-critical temperature. This improved CMF model which is based on the lattice QCD data, has been used to study the properties of both cold QCD matter and neutron star matter. The phase structure in both cases is essentially unchanged, i.e. a chiral first-order phase transition occurs at low temperatures ( $T_{CP} \approx 17$ MeV), and hyperons survive deconfinement to higher densities than non-strange hadrons. The neutron star maximal mass remains close to 2.1 $M_{⊙}$ and the mass-radius diagram is only modified slightly due to the appearance of hyperons and is in agreement with astrophysical observations.
Comments:
11 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2009.10848 [pdf]
PRC(2021)·23 citations
10
[Submitted on 23 Sept 2020] (cross-list from astro-ph.HE)
Screening Effects on Electron Capture Rates and Type Ia Supernova Nucleosynthesis
Kanji Mori · Toshio Suzuki · Michio Honma · Michael A. Famiano · Toshitaka Kajino · Motohiko Kusakabe · A. Baha Balantekin
Type Ia supernovae (SNe Ia) are believed to be a thermonuclear explosion of a white dwarf, but the mass of their progenitors is still an open problem. In near-Chandrasekhar-mass (near-M_Ch) models of SNe Ia, the central density reaches >10^9 g cm^{-3}. The electron chemical potential becomes higher than the Q-values of electron capture (EC) transitions between fp-shell nuclei, so a portion of the available electrons is captured by iron group elements and thus neutron-rich isotopes are formed. Since EC reaction rates are sensitive to the density, the degree of neutronization is a key to distinguish near- and sub-M_Ch models. In order to compare observations and theoretical models, an accurate treatment of EC reactions is necessary. In previous theoretical works, however, effects of electron screening on ECs are ignored. Screening lowers EC rates and thus leads to a higher electron fraction. We implement electron screening on ECs to calculate explosive SN Ia nucleosynthesis in a near-M_Ch single degenerate model. It is found that some of neutron-rich nuclear abundances, namely those of 46,48Ca, 50Ti, 54Cr, 58Fe, 64Ni and 67,70Zn, decrease when screening effects on ECs are considered. Of these, 50Ti, 54Cr and 58Fe are particularly interesting because a significant portion of the solar abundance of these nuclei is presumed to originate from SNe Ia. We conclude that implementing the screening effect on ECs in modern SN Ia models is desirable to precisely calculate abundances of neutron-rich nuclides.
Comments:
7 pages, 7 figures, accepted for publication in ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2009.10925 [pdf]
ApJ(2020)·11 citations
11
[Submitted on 23 Sept 2020] (cross-list from hep-ph)
The lightest flavor--singlet qqq baryons as witnesses to color
Jonathan Estévez🇪🇸 · Felipe J. Llanes-Estrada (Univ. Complutense Madrid)🇪🇸 · Víctor Martínez-Fernández (Nat. Center for Nuclear Research, Warsaw)🇵🇱 · Álvaro Pastor-Gutiérrez (Univ. Heidelberg)🇩🇪
We present a new computation in a field-theoretical model of Coulomb gauge QCD of the first radial and angular excitations of a qqq system in a SU(3) flavor singlet state, Lambda_S. The traditional motivation for the study is that the absence of flavor singlets in the lowest-lying spectrum is a direct consequence of the color degree of freedom. (The calculation is tested with decuplet baryons Delta(1232) and Omega(1672).) We also analyze decay branching fractions of the flavor singlet baryon for various masses with the simplest effective Lagrangians.
Comments:
19 pages, 17 plots
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.11020 [pdf]
PRD(2020)·4 citations
12
[Submitted on 23 Sept 2020] (cross-list from hep-ph)
Directed flow of D mesons at RHIC and LHC: non-perturbative dynamics, longitudinal bulk matter asymmetry and electromagnetic fields
Lucia Oliva🇩🇪 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹
We present a study of the directed flow $v_{1}$ for $D$ mesons discussing both the impact of initial vorticity and electromagnetic field. Recent studies predicted that $v_{1}$ for $D$ mesons is expected to be surprisingly much larger than that of light charged hadrons; we clarify that this is due to a different mechanism leading to the formation of a directed flow with respect to the one of the bulk matter at both relativistic and non-relativistic energies. We point out that the very large $v_{1}$ for $D$ mesons can be generated only if there is a longitudinal asymmetry between the bulk matter and the charm quarks and if the latter have a large non-perturbative interaction in the QGP medium. A quite good agreement with the data of STAR and ALICE is obtained if the diffusion coefficient able to correctly predict the $R_{AA} (p_{T})$ , $v_{2} (p_{T})$ and $v_{3} (p_{T})$ of $D$ meson is employed. Furthermore, the mechanism for the build-up of the $v_{1} (y)$ is associated to a quite small formation time that can be expected to be more sensitive to the initial high-temperature dependence of the charm diffusion coefficient. We discuss also the splitting of $v_{1}$ for $D^{0}$ and $D ˉ^{0}$ due to the electromagnetic field that is again much larger than the one observed for charged particles and in agreement with the data by STAR that have however still error bars comparable with the splitting itself, while at LHC standard electromagnetic profile assuming a constant conductivity is not able to account for the huge splitting observed.
Comments:
16 pages, 24 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2009.11066 [pdf]
JHEP(2021)·46 citations

Affiliations

first authorsco-authorsvia INSPIRE