Nuclear Theory·nucl-th

Tuesday·August 31, 2021

16 papers—9 primary·7 cross-listed

01
Pions in Proton Structure and Everywhere Else
Mary Alberg (1,2)🇺🇸 · Lucas Ehinger (1)🇺🇸 · Gerald A. Miller (2) ((1) Seattle University, (2) University of Washington)🇺🇸
The pion cloud is important in nuclear physics and in a variety of low-energy hadronic phenomena. We argue that it is natural to expect it to also be important in lepton-proton deep inelastic scattering and Drell-Yan studies of proton structure. We compute the necessary consequences of the pion cloud in connection with the recent SeaQuest data. The effects are detailed by using the exact kinematics of the experiment. Good agreement with the measurements is obtained. Thus the universality of pionic effects is understood.
nucl-thhep-phPRD(2022)·12 citations
02
Energy dependent ratios of level-density parameters in superheavy nuclei
A. Rahmatinejad · T. M. Shneidman · G. Adamian · N. V. Antonenko · P. Jachimowicz · M. Kowal
The nuclear level densities and level-density parameters in fissioning nuclei at their saddle points of fission barriers - $a_{f}$ , as well as those for neutron - $a_{n}$ , proton - $a_{p}$ , and $α$ -particle - $a_{α}$ emission residues at the ground states are calculated for isotopic chains of superheavy nuclei with $Z$ =112-120. The calculations are performed with the superfluid formalism using the single-particle energies obtained from the diagonalization of the deformed Woods-Saxon potential. Spectra were generated at global minima of the adiabatic potential energy surfaces, found by the multidimensional minimization method, and at the proper saddle points, found by the "immersion water flow" technique on multidimensional energy grids, with allowed the reflection and axial symmetry breaking. The influence of shell effects on the energy dependence of the ratios of level-density parameters corresponding to residues of the considered decay modes to those of neutron emission is studied. We have shown that, in contrast to the $a_{f} / a_{n}$ ratio, the $a_{p} / a_{n}$ and $a_{α} / a_{n}$ ratios do not show characteristic maxima depending on the excitation energy of the compound nucleus being formed. In the case of alpha decay, we identified the collective enhancement caused by cluster degrees of freedom to play quite an important role. The energetic course of the variability of the level density parameters before reaching the asymptotic value, not taken into account so far, will be of great importance for the estimation of the probabilities of de-excitation cascades via light particles emission in competition with splitting and thus for the determination of the survival probabilities and finally for the total production cross-sections of superheavy nuclei in channels with their (light particles) participation.
nucl-thPRC(2022)·11 citations
03
Quantal diffusion description of isotope production by multinucleon transfer mechanism in $^{48} Ca +^{238} U$ collisions
S. Ayik · M. Arik · E. C. Karanfil · O. Yilmaz · B. Yilmaz · A. S. Umar
As an extension of previous work, we calculate the production cross-section of heavy neutron-rich isotopes by employing the quantal diffusion description to $^{48} Ca +^{238} U$ collisions. The quantal diffusion is deduced from stochastic mean-field approach, and transport properties are determined in terms of time-dependent single-particle wave functions of the time-dependent Hartree-Fock (TDHF) theory. As a result, the approach allows for prediction of production cross-sections without any adjustable parameters. The secondary cross-sections by particle emission are calculated with the help of the statistical GEMINI++ code.
nucl-thPRC(2021)·19 citations
04
Quark condensate and chiral symmetry restoration in neutron stars
Hao-Miao Jin🇨🇳 · Cheng-Jun Xia🇨🇳 · Ting-Ting Sun🇨🇳 · Guang-Xiong Peng🇨🇳
Based on an equivparticle model, we investigate the in-medium quark condensate in neutron stars. Carrying out a Taylor expansion of the nuclear binding energy to the order of $ρ^{3}$ , we obtain a series of EOSs for neutron star matter, which are confronted with the latest nuclear and astrophysical constraints. The in-medium quark condensate is then extracted from the constrained properties of neutron star matter, which decreases non-linearly with density. However, the chiral symmetry is only partially restored with non-vanishing quark condensates, which may vanish at a density that is out of reach for neutron stars.
nucl-thhep-phPLB(2022)·11 citations
05
Ambiguities from nuclear interactions in the $^{12}$ C( $p, 2 p$ ) $^{11}$ B reaction
Nguyen Tri Toan Phuc · Kazuyuki Ogata · Nguyen Hoang Phuc · Bui Duy Linh · Vo Hong Hai · Le Xuan Chung
We investigate the impact of ambiguities coming from the choice of optical potentials and nucleon-nucleon scattering cross sections on the spectroscopic factors extracted from the $^{12}$ C( $p, 2 p$ ) $^{11}$ B reaction. These ambiguities are evaluated by analyzing the cross sections of the $^{12}$ C( $p, 2 p$ ) $^{11}$ B reaction at 100 and 200 MeV within the framework of the distorted-wave impulse approximation with realistic choices of nuclear inputs. The results show that the studied ambiguities are considerably large in this energy region and careful choices of nuclear inputs used in the reaction calculations are required to extract reliable structure information.
nucl-thnucl-exCommun.in Phys.(2022)·0 citations
06
Sensitivity of quasi-free reactions on details of the bound-state overlap functions
C.A. Bertulani · A. Idini · C. Barbieri
It is often stated that heavy-ion nucleon knockout reactions are mostly sensitive to the tails of the bound-state wavefunctions. In contrast, (p,2p) and (p,pn) reactions are known to access information on the full overlap functions within the nucleus. We analyze the oxygen isotopic chain and explore the differences between single-particle wave functions generated with potential models, used in the experimental analysis of knockout reactions, and ab initio computations from self-consistent Green's function theory. Contrary to the common belief, we find that not only the tail of the overlap functions, but also their internal part are assessed in both reaction mechanisms, which are crucial to yield accurately determined spectroscopic information.
nucl-thnucl-exPRC(2021)·13 citations
07
Nuclear landscape in a mapped collective Hamiltonian from covariant density functional theory
Y. L. Yang · Y. K. Wang · P. W. Zhao · Z. P. Li
The nuclear landscape has been investigated within the triaxial relativistic Hartree-Bogoliubov theory with the PC-PK1 density functional, and the beyond-mean-field dynamical correlation energies are taken into account by a microscopically mapped five-dimensional collective Hamiltonian without additional free parameters. The effects of triaxial deformation and dynamical correlations on the nuclear landscape are analyzed. The present results provide the best description of the experimental binding energies, in particular for medium and heavy mass regions, in comparison with the results obtained previously with other state-of-the-art covariant density functionals. The inclusion of the dynamical correlation energies plays an important role in the PC-PK1 results. It is emphasized that the nuclear landscape is considerably extended by the PC-PK1 functional in comparison with the previous results with other density functionals, which may be due to the different isovector properties in the density functionals.
nucl-thPRC(2021)·75 citations
08
Hyperon dynamics and production of multi-strangeness hypernuclei in heavy-ion collisions at 3A GeV
Hui-Gan Cheng🇨🇳 · Zhao-Qing Feng🇨🇳
Within the microscopic transport, systematic investigation of the many facets of hyperons and hypernuclei up to strangeness $S = - 2$ are carried out for $^{197}$ Au + $^{197}$ Au and $^{40}$ Ca + $^{40}$ Ca at the incident energy of $3 A$ GeV. The spatial, temporal and density distributions of hyperon production, absorption and freeze-out are thoroughly investigated. The rapidity and kinetic energy spectra of $Ξ$ hyperons and double $Λ$ hypernuclei are analyzed. It is revealed that the chemical balance of hyperon production is established in baryon-baryon channels while the opposite is found in baryon-meson channels. It turns out that the rapidity spectra of $_{ΛΛ}^{4, 5}$ X are single-peak and more than two orders of magnitude lower than that of $_{Λ}^{3}$ H. Formation of double $Λ$ hypernuclei through $Ξ$ hypernuclei as intermediate states is also discussed in kinematics.
nucl-thPLB(2022)·4 citations
09
Fast & rigorous predictions for $A = 6$ nuclei with Bayesian posterior sampling
T. Djärv · A. Ekström · C. Forssén · H. T. Johansson
We make ab initio predictions for the A = 6 nuclear level scheme based on two- and three-nucleon interactions up to next-to-next-to-leading order in chiral effective field theory ( $χ$ EFT). We utilize eigenvector continuation and Bayesian methods to quantify uncertainties stemming from the many-body method, the $χ$ EFT truncation, and the low-energy constants of the nuclear interaction. The construction and validation of emulators is made possible via the development of JupiterNCSM -- a new M-scheme no-core shell model code that uses on-the-fly Hamiltonian matrix construction for efficient, single-node computations up to $N_{max} = 10$ for $^{6} Li$ . We find a slight underbinding of $^{6} He$ and $^{6} Li$ , although consistent with experimental data given our theoretical error bars. As a result of incorporating a correlated $χ$ EFT-truncation errors we find more precise predictions (smaller error bars) for separation energies: $S_{d} (^{6} Li) = 0.89 \pm 0.44$ MeV, $S_{2 n} (^{6} He) = 0.20 \pm 0.60$ MeV, and for the beta decay Q-value: $Q_{β^{-}} (^{6} He) = 3.71 \pm 0.65$ MeV. We conclude that our error bars can potentially be reduced further by extending the model space used by JupiterNCSM.
nucl-thnucl-exphysics.data-anPRC(2022)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE