Nuclear Theory·nucl-th

Wednesday·September 1, 2021

14 papers—8 primary·6 cross-listed

01
BCS solutions and effective quarks energies of the QCD Hamiltonian in the Coulomb gauge
Tochtli Yepez-Martinez🇲🇽 · Peter O. Hess🇲🇽 · Osvaldo Civitarese🇦🇷
The exploration of the non-perturbative regime of QCD, that is the low-energy portion of the hadron spectrum, requires the adoption of theoretical methods more frequently applied to other, more conventional, quantum many body systems, like the atomic nucleus, solid state systems, etc. In this work we have adopted, as a first step, the well-known BCS method to describe correlations between pairs of quarks and the associated ground state. Going beyond the BCS method would imply the inclusion of correlations by means of the TDA or RPA approximations. Since, we are interested in analyzing the role of constituent quark-pair correlations in the structure of hadrons we are restricted to the use of BCS as said before. The starting Hamiltonian is the effective Coulomb plus linear potential which we have used in previous calculations and performed a two-step approach, firstly by pre-diagonalizing it to built a single particle spectrum, and then, secondly, by applying the BCS transformations to it. Then, we have explored the resulting structure of the low energy meson spectra in terms of quasiparticle degrees of freedom. The dependence of the results upon the parameters which enter in the calculations is explored in detail, at the level of the quasiparticle mean-field approximation.
nucl-thNPA(2023)·3 citations
02
Production of neutron-rich heavy nuclei around N = 162 in multinucleon transfer reactions
Cheng Peng · Zhao-Qing Feng
Within the framework of the dinuclear system model, the production mechanism of neutron-rich heavy nuclei around N = 162 has been investigated systematically. The isotopic yields in the multinucleon transfer reaction of $^{238}$ U + $^{248}$ Cm was analyzed and compared the available experimental data. Systematics on the production of superheavy nuclei via $^{238}$ U on $^{252, 254}$ Cf, $^{254}$ Es and $^{257}$ Fm is investigated. It is found that the shell effect is of importance in the formation of neutron-rich nuclei around N=162 owing to the enhancement of fission barrier. The fragments in the multinucleon transfer reactions manifest the broad isotopic distribution and are dependent on the beam energy. The polar angles of the fragments tend to the forward emission with increasing the beam energy. The production cross sections of new isotopes are estimated and heavier targets are available for the neutron-rich superheavy nucleus formation. The optimal system and beam energy are proposed for the future experimental measurements.
nucl-thEPJA(2022)·5 citations
03
Systematics on production of superheavy nuclei $Z = 119 - 122$ in fusion-evaporation reactions
Fei Niu · Peng-Hui Chen · Zhao-Qing Feng
The fusion dynamics on the formation of superheavy nuclei is investigated thoroughly within the dinuclear system model. The Monte Carlo approach is implemented into the nucleon transfer process for including all possible orientations, at which the dinuclear system is assumed to be formed at the touching configuration of dinuclear fragments. The production cross sections of superheavy nuclei Cn, Fl, Lv, Ts and Og are calculated and compared with the available data from Dubna. The evaporation residue excitation functions in the channels of pure neutrons and charged particles are analyzed systematically. The combinations with $^{44}$ Sc, $^{48, 50}$ Ti, $^{49, 51}$ V, $^{52, 54}$ Cr, $^{58, 62}$ Fe and $^{62, 64}$ Ni bombarding the actinide nuclides $^{238}$ U, $^{244}$ Pu, $^{248}$ Cm, $^{247, 249}$ Bk, $^{249, 251}$ Cf, $^{252}$ Es and $^{243}$ Am are calculated for producing the superheavy elements with Z=119-122. It is found that the production cross sections sensitively depend on the neutron richness of reaction system. The structure of evaporation residue excitation function is related to the neutron separation energy and fission barrier of compound nucleus.
nucl-thNucl.Sci.Tech.(2021)·25 citations
04
First-order Phase Transition and Resulted Expansion in Momentum Space
Feng Li🇨🇳
We point out, according to the principle of entropy growth, that the volume occupied by the system in the momentum space should expand during the first-order phase transition. Such an expansion is visualized by the simulation using the transport model based on a NJL-typed Lagrangian, and quantified by several observables, some of which, proposed for the first time in this article, could be the probes of the first-order phase transition either between the quark gluon plasma and the hadronic phase taking place in the heavy-ion collisions or of the other expanding systems.
nucl-thnucl-ex0 citations
05
Three-body optical potentials in $(d, p)$ reactions and their influence on indirect study of stellar nucleosynthesis
M. J. Dinmore · N.K. Timofeyuk · J.S. Al-Khalili
Model uncertainties, arising due to suppression of target excitations in the description of deuteron scattering and resulting in a modification of the two-body interactions in a three-body system, are investigated for several $(d, p)$ reactions serving as indirect tools for studying the astrophysical $(p, γ)$ reactions relevant to $r p$ -process. The three-body nature of deuteron-target potential is treated within adiabatic distorted wave approximation (ADWA) which relies on dominant contribution from the components of the three-body deuteron-target wave function with small $n$ - $p$ separations. This results in a simple prescription for treating the explicit energy-dependence of two-body optical potentials in a three-body system requiring nucleon optical potentials to be evaluated at a shifted energy with respect to the standard value of half the deuteron incident energy. In addition, the ADWA allows for leading-order multiple scattering effects to be estimated, which leads to a simple renormalization of the adiabatic potential's imaginary part by the factor of two. These effects are assessed using both nonlocal and local optical potential systematics for $^{26}$ Al, $^{30}$ P, $^{34}$ Cl and $^{56}$ Ni targets at deuteron incident energy of 12 MeV typical for experiments with radioactive beams in inverse kinematics. The model uncertainties induced by the three-body nature of deuteron-target scattering are found to be within 40 $%$ both in the main peak of angular distributions and in total $(d, p)$ cross sections. At higher deuteron energies, around 60 MeV, model uncertainties can reach 100\% in the total cross sections. A few examples of application to astrophysically interesting proton resonances in $^{27}$ Si and $^{57}$ Cu obtained using $(d, p)$ reactions and mirror symmetry are given.
nucl-thnucl-exPRC(2021)·2 citations
06
Structure of ultra-magnetised neutron stars
Debarati Chatterjee🇮🇳 · Jerome Novak🇫🇷 · Micaela Oertel🇫🇷
In this review we discuss self-consistent methods to calculate the global structure of strongly magnetised neutron stars within the general-relativistic framework. We outline why solutions in spherical symmetry cannot be applied to strongly magnetised compact stars, and elaborate on a consistent formalism to compute rotating magnetised neutron star models. We also discuss an application of the above full numerical solution for studying the influence of strong magnetic fields on the radius and crust thickness of magnetars. The above technique is also applied to construct a "universal" magnetic field profile inside the neutron star, that may be useful for studies in nuclear physics. The methodology developed here is particularly useful to interpret multi-messenger astrophysical data of strongly magnetised neutron stars.
nucl-thastro-ph.HEEPJA(2021)·22 citations
07
The BEST framework for the search for the QCD critical point and the chiral magnetic effect
Xin An🇺🇸 · Marcus Bluhm🇫🇷 · Lipei Du🇺🇸 · Gerald V. Dunne🇺🇸 · Hannah Elfner🇩🇪 · Charles Gale🇨🇦 · Joaquin Grefa🇺🇸 · Ulrich Heinz🇺🇸 · Anping Huang🇺🇸 · Jamie M. Karthein🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Volker Koch🇺🇸 and 31 other authors
The Beam Energy Scan Theory (BEST) Collaboration was formed with the goal of providing a theoretical framework for analyzing data from the Beam Energy Scan (BES) program at the relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory. The physics goal of the BES program is the search for a conjectured QCD critical point as well as for manifestations of the chiral magnetic effect. We describe progress that has been made over the previous five years. This includes studies of the equation of state and equilibrium susceptibilities, the development of suitable initial state models, progress in constructing a hydrodynamic framework that includes fluctuations and anomalous transport effects, as well as the development of freezeout prescriptions and hadronic transport models. Finally, we address the challenge of integrating these components into a complete analysis framework. This document describes the collective effort of the BEST Collaboration and its collaborators around the world.
nucl-thhep-lathep-phnucl-exNPA(2022)·152 citations
08
Consequences of increased hypertriton binding for $s$ -shell $Λ$ -hypernuclear systems
M. Schäfer🇮🇱 · B. Bazak🇮🇱 · N. Barnea🇮🇱 · A. Gal🇮🇱 · J. Mareš🇨🇿
Consequences of increasing the binding energy of the hypertriton ground state $_{Λ}^{3} H (J^{P} = \frac{1}{2}^{+})$ from the emulsion value $B_{Λ}^{EMUL} (_{Λ}^{3} H_{g.s.})$ =0.13 $\pm$ 0.05 MeV to the STAR value $B_{Λ}^{STAR} (_{Λ}^{3} H) = (0.41 \pm 0.12 \pm 0.11)$ MeV are studied for $s$ -shell hypernuclei within a pionless EFT approach at leading order, constrained by the binding energies of the $0^{+}$ and $1^{+}$ $_{Λ}^{4} H$ states. The stochastic variational method is used in bound-state calculations, whereas the inverse analytic continuation in the coupling constant method is used to locate $S$ -matrix poles of continuum states. It is found that the $Λ nn (\frac{1}{2}^{+})$ resonance becomes broader and less likely to be observed experimentally, whereas the $_{Λ}^{3} H (\frac{3}{2}^{+})$ spin-flip virtual state moves closer to the $Λ d$ threshold to become a shallow bound state for specific $Λ N$ interaction strengths. The effect of such a near-threshold $_{Λ}^{3} H (\frac{3}{2}^{+})$ state on femtoscopic studies of $Λ$ -deuteron correlations, and its lifetime if bound, are discussed. Increasing $B_{Λ} (_{Λ}^{3} H_{g.s.})$ moderately, up to $\sim$ 0.5 MeV, hardly affects calculated values of $B_{Λ} (_{Λ}^{5} He)$ .
nucl-thPRC(2022)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE