Nuclear Theory·nucl-th

Thursday·July 4, 2019

9 papers—6 primary·3 cross-listed

01
Deuteron-alpha scattering: separable vs nonseparable Faddeev approach
L. Hlophe🇺🇸 · Jin Lei🇺🇸 · Ch. Elster🇺🇸 · A. Nogga🇩🇪 · F.M. Nunes🇺🇸 · D. Jurčiukonis🇱🇹 · A. Deltuva🇱🇹
{\bf Background} Deuteron induced reactions are widely used to probe nuclear structure and astrophysical information. Those (d,p) reactions may be viewed as three-body reactions and described with Faddeev techniques. {\bf Purpose} Faddeev-AGS equations in momentum space have a long tradition of utilizing separable interactions in order to arrive at sets of coupled integral equations in one variable. However, it needs to be demonstrated that observables calculated based on separable interactions agree exactly with those based on nonseparable forces. {\bf Methods} Momentum space AGS equations are solved with separable and nonseparable forces as coupled integral equations. {\bf Results} Deuteron-alpha scattering is calculated via momentum space AGS equations using the CD-Bonn neutron-proton force and a Woods-Saxon type neutron(proton)- $^{4}$ He force, for which the Pauli-forbidden S-wave bound state is projected out. Elastic as well as breakup observables are calculated and compared to results in which the interactions in the two-body sub-systems are represented by separable interactions derived in the Ernst-Shakin-Thaler (EST) framework. {\bf Conclusions} We find that the calculations based on the separable representation of the interactions and the original interactions give results that are in excellent agreement. Specifically, integrated cross sections and angular distributions for elastic scattering agree within $\approx$ 1\%, which is well below typical experimental errors. In addition, the five-fold differential cross sections corresponding to breakup of the deuteron agree extremely well.
nucl-thPRC(2019)·12 citations
02
Prediction of stable superheavy nuclei
H.C. Manjunatha · L. Seenappa · K.N. Sridhar
We have investigated most stable superheavy nuclei by studying the decay properties such as alpha decay, cluster decay and spontaneous fission. We have investigated nine stable nuclei in the island of stability which can be detected through fission are 318123(10.5ms), 319123(4.68{\mu}s), 317124(1.74x104 y), 318124(2.70x101 y), 319124(2.83x10-2 y), 320124(1.91x10-5 y), 319125(2.46x109 y), 320125(3.81x106 y) and 321125(3.99x103 y). Present work also investigates three stable superheavy nuclei which can be detected through alpha decay which are 318125(1.03x1012 y), 319126(5.77x1011 y) and 320126(3.99x1010 y). These nuclei will become most stable nuclei if they synthesized in the laboratory. The identified twelve stable nuclei is the evidence for the hypothesis of island of stability
nucl-th0 citations
03
Photo-absorption on deuteron contributed by d^*(2380) resonance
Yubing Dong🇨🇳 · Pengnian Shen🇨🇳 · Zoneye Zhang🇨🇳
In order to understand the possible physical nature of the newly observed resonance $d^{*} (2380)$ , we calculate the real photo-absorption cross section on deuteron contributed by the resonance $d^{*} (2380)$ by considering the electromagnetic transition amplitude of $γ + d \to d^{*} (2380)$ . In our interpretation, the $d^{*} (2380)$ is regarded as a compact six-quark system with mainly two components of $ΔΔ$ and hidden-color clusters $C_{8} C_{8}$ . We find that only the next-to-leading terms contribute the $γ + d \to d^{*} (2380)$ and the obtained photo-absorption cross section is quite small which is in the order of 10 $nb$ . Compared with data measured at ELPH and Mainz recently, it is almost about 20 times smaller.
nucl-thInt.J.Mod.Phys.A(2019)·8 citations
04
Exact solutions of the relativistic Boltzmann equation in the relaxation time approximation
Ewa Maksymiuk🇵🇱
This Thesis concentrates on the analysis of coupled RTA (relaxation time approximation) kinetic equations for bosons and fermions. Bosons are treated as massless particles, while fermions have a finite mass. Using analytic and numerical methods we find exact solutions for such a mixture in the case of one-dimensional, boost-invariant expansion (for systems which are transversally homogeneous). In this way, several earlier results obtained for one-component systems and classical particles are generalized.
nucl-th0 citations
05
Introduction to Nuclear-Reaction Theory
Pierre Capel
These notes summarise the lectures I gave during the summer school "International Scientific Meeting on Nuclear Physics" at La Rábida in Spain in June 2018. They offer an introduction to nuclear-reaction theory, starting with the basics in quantum scattering theory followed by the main models used to describe breakup reactions: the Continuum Discretised Coupled Channel method (CDCC),the Time-Dependent approach (TD) and the eikonal approximation. These models are illustrated on the study of the exotic structure of halo nuclei.
nucl-thnucl-exSpringer Proc.Phys.(2019)·0 citations
06
Modeling $^{19}$ B as a $^{17}$ B-n-n three-body system in the unitary limit
Emiko Hiyama🇯🇵 · Rimantas Lazauskas🇫🇷 · F. Miguel Marqués🇫🇷 · Jaume Carbonell🇫🇷
We present a model description of the bound $^{17}$ B isotope in terms of a $^{17}$ B-n-n three-body system where the two-body subsystems $^{17}$ B-n and n-n are unbound (virtual) states close to the unitary limit. The $^{17}$ B ground state is well described in terms of two-body potentials only, and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be naturally used to describe the recently discovered resonant states in $^{20, 21}$ B.
nucl-thnucl-exPRC(2019)·29 citations
07
Three-pion contribution to hadronic vacuum polarization
Martin Hoferichter🇺🇸 · Bai-Long Hoid🇩🇪 · Bastian Kubis🇩🇪
We address the contribution of the $3 π$ channel to hadronic vacuum polarization (HVP) using a dispersive representation of the $e^{+} e^{-} \to 3 π$ amplitude. This channel gives the second-largest individual contribution to the total HVP integral in the anomalous magnetic moment of the muon $(g - 2)_{μ}$ , both to its absolute value and uncertainty. It is largely dominated by the narrow resonances $ω$ and $ϕ$ , but not to the extent that the off-peak regions were negligible, so that at the level of accuracy relevant for $(g - 2)_{μ}$ an analysis of the available data as model independent as possible becomes critical. Here, we provide such an analysis based on a global fit function using analyticity and unitarity of the underlying $γ^{*} \to 3 π$ amplitude and its normalization from a chiral low-energy theorem, which, in particular, allows us to check the internal consistency of the various $e^{+} e^{-} \to 3 π$ data sets. Overall, we obtain $a_{μ}^{3 π} ∣_{\leq 1.8 GeV} = 46.2 (6) (6) \times 1 0^{- 10}$ as our best estimate for the total $3 π$ contribution consistent with all (low-energy) constraints from QCD. In combination with a recent dispersive analysis imposing the same constraints on the $2 π$ channel below $1 GeV$ , this covers nearly $80%$ of the total HVP contribution, leading to $a_{μ}^{HVP} = 692.3 (3.3) \times 1 0^{- 10}$ when the remainder is taken from the literature, and thus reaffirming the $(g - 2)_{μ}$ anomaly at the level of at least $3.4 σ$ . As side products, we find for the vacuum-polarization-subtracted masses $M_{ω} = 782.63 (3) (1) MeV$ and $M_{ϕ} = 1019.20 (2) (1) MeV$ , confirming the tension to the $ω$ mass as extracted from the $2 π$ channel.
↳ hep-phhep-exhep-latnucl-thJHEP(2019)·498 citations
08
Thermal behaviors of light scalar resonances at low temperatures
Rui Gao🇨🇳 · Zhi-Hui Guo🇨🇳 · Jin-Yi Pang🇩🇪
We study the thermal properties of the lowest multiplet of the QCD light-flavor scalar resonances, including the $f_{0} (500) / σ$ , $K_{0}^{*} (700) / κ$ , $f_{0} (980)$ and $a_{0} (980)$ , in the framework of unitarized $U (3)$ chiral perturbation theory. After the successful fits to the meson-meson scattering inputs, such as the phase shifts and inelasticities, we obtain the unknown parameters and further calculate the resonance poles and their residues at zero temperature. By including the finite-temperature effects in the unitarized meson-meson scattering amplitudes, the thermal behaviors of the scalar resonance poles in the complex energy plane are studied. The masses of $σ$ and $κ$ are found to considerably decrease when increasing the temperatures, while their widths turn out to be still large when the temperatures reach around $200$ MeV. In contrast, both the masses and widths of the $f_{0} (980)$ and $a_{0} (980)$ are only slightly changed.
↳ hep-phhep-latnucl-thPRD(2019)·18 citations
09
Three regimes of QCD
L. Ya. Glozman🇦🇹
While the QCD Lagrangian as the whole is only chirally symmetric, its electric part has larger chiral-spin SU(2)_{CS} and SU(2N_F) symmetries. This allows separation of the electric and magnetic interactions in a given reference frame. Artificial truncation of the near-zero modes of the Dirac operator results in the emergence of the SU(2)_{CS} and SU(2N_F) symmetries in hadron spectrum. This implies that while the confining electric interaction is distributed among all modes of the Dirac operator, the magnetic interaction is located at least predominantly in the near-zero modes. Given this observation one could anticipate that above the pseudocritical temperature, where the near-zero modes of the Dirac operator are suppressed, QCD is SU(2)_{CS} and SU(2N_F) symmetric, which means absence of deconfinement in this regime. Solution of the N_F=2 QCD on the lattice with a chirally symmetric Dirac operator reveals that indeed in the interval Tc - 3Tc QCD is approximately SU(2)_{CS} and SU(2N_F) symmetric which implies that degrees of freedom are chirally symmetric quarks bound by the chromoelectric field into color-singlet objects without the chromomagnetic effects. This regime is referred to as a Stringy Fluid. At larger temperatures this emergent symmetry smoothly disappears and QCD approaches the Quark-Gluon Plasma regime with quasifree quarks. The Hadron Gas, the Stringy Fluid and the Quark-Gluon Plasma differ by symmetries, degrees of freedom and properties.
↳ hep-phhep-lathep-thnucl-thInt.J.Mod.Phys.A(2021)·15 citations

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