Nuclear Theory·nucl-th
10 papers—8 primary·2 cross-listed
Several persistent problems in strangeness nuclear physics are discussed in this opening talk at HYP2018, Portsmouth-Norfolk VA, June 2018: (i) the H and n (if existing) lifetimes; (ii) charge symmetry breaking in hypernuclei; (iii) the overbinding of He which might be related to the hyperon puzzle in neutron stars; and (iv) does (1405) survive in strange hadronic matter?
Qing Zhao · Mengjiao Lyu · Zhongzhou Ren · Takayuki Myo · Hiroshi Toki · Kiyomi Ikeda · Hisashi Horiuchi · Masahiro Isaka · Taiichi Yamada
The high-momentum antisymmetrized molecular dynamics (HMAMD) is a new promising framework with significant analytical simplicity and efficiency inherited from its antisymmetrized molecular dynamics in describing the high momentum correlations in various nuclear states. In the aim of further improving the numerical efficiency for the description of nucleon-nucleon correlation, we introduce a new formulation by including a new Gaussian weighted basis of high momentum pairs in the HMAMD wave function, with which very rapid convergence is obtained in numerical calculation. It is surprising that the very high-momentum components in the new HMAMD basis are found to be almost equivalent to the contact representation of the nucleon-nucleon pairs with very small nucleon-nucleon distance. The explicit formulation for the contact term significantly improves the numerical efficiency of the HMAMD method, which shows the importance of the contact correlation in the formulation of light nuclei.
For a single-channel nucleon-nucleon scattering, a well-known and convenient variable phase approach is considered, which is widely used for practical problems of atomic and nuclear physics. Approximation of the - and - scattering phases obtained for the modern realistic phenomenological nucleon-nucleon potential Reid93 was carried out. The approximation function is used as a well-known formula for a parabolic-type quadratic function.
Within the framework of the study of radiative corrections to the polarization observed in elastic -scattering in leptonic variables have been calculated the Born values of vector AB^L, AB^T and tensor AB^LL, AB^TT, AB^LT asymmetries. The deuteron wave functions in coordinate representation for eight nucleon-nucleon potentials (Nijm1, Nijm2, Nijm93, Reid93, Argonne v18, OBEPC, MT and Paris) have been used for numerical calculations of vector AB^i(p,teta) and tensor AB^ij(p,teta) asymmetries. The angular-momentum dependence of values vector and tensor asymmetries have been also evaluated in 3D format for Reid93 potentials.
Iurii Karpenko🇫🇷 · Francesco Becattini🇮🇹
STAR collaboration at RHIC has recently measured the polarization of hyperons in non-central heavy ion collisions in the RHIC Beam Energy Scan (BES) program. The magnitude of the polarization was found to decrease from few percents at the lowest BES energies to % at the top RHIC energy. The polarization signal has been reproduced in different hydrodynamic calculations assuming a thermodynamic spin-vorticity coupling mechanism at the Cooper-Frye hypersurface. In this work an extension of our existing calculations of the polarization in the RHIC BES program to the top RHIC and 2.76 TeV LHC energies is presented. The longitudinal component of the polarization, which is the dominant component of the polarization at the LHC energies, is discussed. Finally we show that the global polarization of originates dominantly from the relativistic analogue of the classical vorticity, whereas the quadrupole longitudinal component originates from the gradients of temperature and acceleration of the medium when the s are produced out of the fluid.
Jehee Lee🇯🇵 · Nodoka Yamanaka🇫🇷 · Emiko Hiyama🇯🇵
We calculate the contribution of the meson exchange process generated by the Cabibbo-Kobayashi-Maskawa matrix to the electric dipole moment (EDM) of the Be nucleus by considering the channel coupling. It is found that the effect of the Pauli exclusion principle is not important intermediate state, and that the result is consistent with the EDM of Be calculated with the interactions as a perturbation without considering the nucleus-hypernucleus mixing. Our result suggests that the effect of the interactions is neither suppressed nor enhanced in nuclei, if the difference of binding energies between the nucleus and the hypernucleus is small compared to the hyperon-nucleon mass difference.
Generalized symmetric Woods-Saxon potential (GSWSP) energy well has a significant importance not only in nuclear physics but also in atomic and molecular physics. A GSWSP energy well takes the surface effects (describing e.g. repulsive interaction at the nucleus edge in nuclear physics) into account in addition to the volume effect. These effects can be, in general, both repulsive or attractive. In this paper, the recently obtained bound state solution of the Klein-Gordon equation with vector and scalar GSWSP energy in the spin symmetry limit is used to calculate a neutral pion's energy spectra in attractive and repulsive cases via various potential parameters. Then, the spectra are employed to find the thermodynamic functions such as Helmholtz free energy, entropy, internal energy, and specific heat. These functions in the attractive and repulsive cases are compared comprehensively. Finally, the role of the shape parameters on the thermodynamic functions in repulsive and attractive cases, respectively, is analyzed.
Erik Olsen · Witold Nazarewicz
New superheavy nuclei are often identified through their characteristic -decay energies, which requires accurate calculations of values. While many predictions are available, little is known about their uncertainties, and this makes it difficult to carry out extrapolations to yet-unknown systems. This work aims to analyze several models, compare their predictions to available experimental data, and study their performance for the unobserved -decay chains of 120 and 120, which are of current experimental interest. Our quantified results will also serve as a benchmark for future, more sophisticated statistical studies. We use nuclear superfluid Density Functional Theory (DFT) with several Skyrme energy density functionals (EDFs). To estimate systematic model uncertainties we employ uniform model averaging. We evaluated the values for even-even nuclei from Fm to . For well deformed nuclei between Fm and Ds, we find excellent consistency between different model predictions, and a good agreement with experiment. For transitional nuclei beyond Ds, inter-model differences grow, resulting in an appreciable systematic error. In particular, our models underestimate for the heaviest nucleus Og. The robustness of DFT predictions for well deformed superheavy nuclei supports the idea of using experimental values, together with theoretical predictions, as reasonable indicators. Unfortunately, this identification method is not expected to work well in the region of deformed-to-spherical shape transition as one approaches . The use of values in the identification of new superheavy nuclei will benefit greatly from both progress in developing new spectroscopic-quality EDFs and more sophisticated statistical techniques of uncertainty quantification.
Hungchong Kim🇰🇷 · K. S. Kim🇰🇷 · Myung-Ki Cheoun🇰🇷 · Daisuke Jido🇯🇵 · Makoto Oka🇯🇵
In this work, we investigate additional signatures to support the tetraquark mixing framework that has been recently proposed as a possible structure for the two nonets, namely , , , in the light nonet, , , , in the heavy nonet. First, we advocate that the two nonets form the flavor nonet approximately satisfying the Gell-Mann--Okubo mass relation. Then we reexamine the mass ordering generated from the tetraquark nonets and show that this mass ordering is satisfied by the two nonets although the ordering in the heavy nonet is marginal. The marginal mass ordering however can be regarded as another signature for tetraquarks because it can be explained partially by the hyperfine masses calculated from the tetraquark mixing framework. The tetraquark mixing parameters are found to be independent of isospins giving additional support for the formation of the flavor nonets. In addition, we discuss the other approaches like two-quark pictures or meson-meson bound states, and their possible limitations in explaining the two nonets. As a peculiar signature distinguished from other approaches, we investigate the fall-apart coupling strengths into two vector mesons from our tetraquarks. Coupling strengths into the two-vector modes are found to enhance strongly in the heavy nonet while they are suppressed in the light nonet. The coupling ratios, which depend on the isospin channel, are found to be huge around . This trend in the two-vector modes, which is opposite to that in the two-pseudoscalar fall-apart modes, can provide another testing ground for the tetraquark mixing framework. Some experimental evidences related to the phenomena are discussed particularly from the resonances belonging to the heavy nonet.
Natasha Sharma🇮🇳 · Jean Cleymans🇿🇦 · Boris Hippolyte🇫🇷 · Masimba Paradza🇿🇦
% An analysis is made of the particle composition (hadrochemistry) of the final state in proton-proton (p-p), proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions as a function of the charged particle multiplicity (). The thermal model is used to determine the chemical freeze-out temperature as well as the radius and strangeness saturation factor . Three different ensembles are used in the analysis namely, the grand canonical ensemble, the canonical ensemble with exact strangeness conservation and the canonical ensemble with exact baryon number, strangeness and electric charge conservation. It is shown that for high multiplicities (at least 20 charged hadrons in the mid-rapidity interval considered) the three ensembles lead to the same results.
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