Nuclear Theory·nucl-th

Wednesday·November 9, 2022

9 papers—4 primary·5 cross-listed

01
Neutron skin of $^{27}$ Al with Skyrme and Korea-IBS-Daegu-SKKU density functionals
Hana Gil · Chang Ho Hyun · K. S. Kim
Recent measurement of the parity-violating (PV) asymmetry in the elastic electron scattering on $^{27}$ Al target evokes the interest in the distribution of the neutron in the nucleus. In this work, we calculate the neutron skin thickness ( $R_{n p}$ ) of $^{27}$ Al with nonrelativistic nuclear structure models. We focus on the role of the effective mass, symmetry energy and pairing force. Models are selected to have effective masses in the range $(0.58 - 1.05) M$ where $M$ is the nucleon mass in free space, and stiffness of the symmetry energy is varied by choosing the slope of the symmetry energy in the range 9.4 -- 100.5 MeV. Effect of pairing force is investigated by calculating $R_{n p}$ with and without pairing, and using two different forms of the pairing force. With nine models, we obtain $R_{n p} = 0.001 - 0.014$ fm. The result is independent of the effective mass, symmetry energy, and the form of pairing force. However, $R_{n p}$ is negative when the pairing force is switched off, so the pairing force plays an essential role to make $R_{n p}$ positive and constrained in a narrow range. We also calculate the PV asymmetry ( $A_{pv}$ ) in the elastic electron- $^{27}$ Al scattering in the Born approximation at the kinematics of the Qweak experiment. We obtain a very narrow-ranged result $A_{pv} =$ (2.07 -- 2.09) $\times 1 0^{- 6}$ . The result is consistent with the experiment and insensitive to the effective mass, symmetry energy and pairing force.
nucl-thMod.Phys.Lett.A(2024)·1 citation
02
Electromagnetic fields in ultra-peripheral relativistic heavy-ion collisions
Jie Zhao🇨🇳 · Jinhui Chen🇨🇳 · Xu-Guang Huang🇨🇳 · Yu-Gang Ma🇨🇳
Ultraperipheral heavy-ion collisions (UPCs) offer unique opportunities to study processes under strong electromagnetic fields. In these collisions, highly charged fast-moving ions carry strong electromagnetic fields that can be effectively treated as photon fluxes. The exchange of photons can induce photonuclear and two-photon interactions, and excite ions. This excitation of the ions results in Coulomb dissociation with the emission of photons, neutrons, and other particles. Additionally, the electromagnetic fields generated by the ions can be sufficiently strong to enforce mutual interactions between the two colliding ions. Consequently, the two colliding ions experienced an electromagnetic force that pushed them in opposite directions, causing a back-to-back correlation in the emitted neutrons. Using a Monte Carlo simulation, we qualitatively demonstrated that the above electromagnetic effect is large enough to be observed in UPCs, which would provide a clear means to study strong electromagnetic fields and their effects.
nucl-thnucl-exNucl.Sci.Tech.(2024)·32 citations
03
A Toy Model for Low Energy Nuclear Fusion
Kaanapuli Ramkumar · Harishyam Kumar · Pankaj Jain
We study the fusion of a proton with a nucleus with the emission of two photons at low incident energy of the order of eV or smaller. We use a step model for the repulsive potential between proton and the nuclei. We consider the reaction both in free space and inside a medium. We make a simple model for the medium by assuming a hard wall potential beyond a certain length scale. This essentially leads to discretization of the energy spectrum which is expected inside a medium and is seen both for a crystalline lattice structure and for amorphous materials. We use second order perturbation theory to compute the transition rate. We find that the rate in free space is very small. However in medium, the rate may be substantial. Hence, we conclude that nuclear fusion reactions may take place at low energies at observable rates.
nucl-thPramana(2023)·6 citations
04
Study of structure and radii for $^{20 - 31}$ Na isotopes using microscopic interactions
Subhrajit Sahoo · Praveen C. Srivastava · Toshio Suzuki
In this work, Na isotopes with mass varying from $A =$ 20 to 31 have been studied using DJ16A, JISP16 and N3LO microscopic effective interactions in the $s d$ -shell. These effective interactions are derived for $s d$ -shell using no-core shell model wavefunctions and a unitary transformation method. We have also performed calculation with IMSRG effective interactions targeted for a particular nucleus. The studies include a detailed analysis of ground state binding energy, low-lying spectra, and electromagnetic properties such as reduced electric quadrupole transition strengths, quadrupole and magnetic dipole moments of the Na chain. The results obtained from these microscopic effective interactions were compared with the experimental data as well as with the results of phenomenological interaction USDB. The charge radii of Na isotopes are evaluated using shell model harmonic oscillator wave functions. In addition to charge radii, matter radii and neutron skin thickness in the Na chain are discussed with a focus on neutron-deficient Na isotopes.
nucl-thnucl-exNPA(2023)·12 citations
05
Revealing the Signal of QCD Phase Transition in Heavy-Ion Collisions
Yi Lu🇨🇳 · Fei Gao🇨🇳 · Xiaofeng Luo🇨🇳 · Lei Chang🇨🇳 · Yu-xin Liu🇨🇳
We propose a novel method to construct the Landau thermodynamic potential directly from the fluctuations measured in heavy-ion collisions. The potential is capable of revealing the signal of the critical end-point (CEP) and the first order phase transition (FOPT) of QCD in the system even away from the phase transition region. With the available experimental data, we show that the criterion of the FOPT is negative for most of the collision energies which indicates no signal of FOPT. The data at $s_{NN} = 7.7$ GeV with 0-5% centrality shows a different behavior and the mean value of the data satisfies the criterion. However, the uncertainty is still too large to make a certain conclusion. The higher order fluctuations are also required for confirming the signal. We emphasize therefore that new measurements with higher precision for the $C_{1, ..., 6}$ within 0-5% centrality in the vicinity of $s_{NN} = 7.7$ GeV are in demand which may finally reveal the signal of QCD phase transition.
↳ hep-phnucl-exnucl-th1 citation
06
Gravitational chiral anomaly and anomalous transport for fields with spin 3/2
Georgy Yu. Prokhorov🇷🇺 · Oleg V. Teryaev🇷🇺 · Valentin I. Zakharov🇷🇺
In a fluid with vorticity and acceleration, an axial current arises in the third order of gradient expansion, called the kinematical vortical effect (KVE). While existing in the absence of gravitational fields, it is nevertheless associated with effects in curved space-time, namely with the gravitational chiral quantum anomaly. In this paper, the KVE transport coefficients were found using the Zubarev quantum-statistical density operator for the Rarita-Schwinger-Adler theory, which includes fields with spins 3/2 and 1/2. A prediction is made about the possible form of the transport coefficients for massless fields with arbitrary spin.
↳ hep-thgr-qcnucl-thPLB(2023)·9 citations
07
PANDORA project: photo-nuclear reactions below $A = 60$
A. Tamii · L. Pellegri · P.-A. Söderström · D. Allard · S. Goriely · T. Inakura · E. Khan · E. Kido · M. Kimura · E. Litvinova · S. Nagataki · P. von Neumann-Cosel and 69 other authors
Photo-nuclear reactions of light nuclei below a mass of $A = 60$ are studied experimentally and theoretically by the PANDORA (Photo-Absorption of Nuclei and Decay Observation for Reactions in Astrophysics) project. Two experimental methods, virtual-photon excitation by proton scattering and real-photo absorption by a high-brilliance gamma-ray beam produced by laser Compton scattering, will be applied to measure the photo-absorption cross sections and the decay branching ratio of each decay channel as a function of the photon energy. Several nuclear models, e.g. anti-symmetrized molecular dynamics, mean-field type models, a large-scale shell model, and ab initio models, will be employed to predict the photo-nuclear reactions. The uncertainty in the model predictions will be evaluated from the discrepancies between the model predictions and the experimental data. The data and the predictions will be implemented in a general reaction calculation code TALYS . The results will be applied to the simulation of the photo-disintegration process of ultra-high-energy cosmic rays in inter-galactic propagation.
↳ nucl-exastro-ph.HEnucl-thEPJA(2023)·30 citations
08
Two-body nonleptonic decays of the heavy mesons in the factorization approach
Shuo-Ying Yu🇨🇳 · Xian-Wei Kang🇨🇳 · V. O. Galkin🇷🇺
In the framework of the factorization approach we calculate the branching fractions of 100 two-body nonleptonic decay channels in total, including 44 channels of the charm meson decays and 56 channels of the bottom meson decays. For charm meson decays, we test and confirm the previous observation that taking the limit for the number of colors $N \to \infty$ significantly improves theoretical predictions. For bottom meson decays, the penguin contributions are included in addition. As an essential input, we employ the weak decay form factors obtained in the framework of the relativistic quark model based on the quasi-potential approach. These form factors have well been tested by calculating observables in the semileptonic $D$ and $B$ meson decays and confronting obtained results with experimental data. In general, the predictions for the nonleptonic decay branching fractions are acceptable. However, for a quantitative calculation it is necessary to account for a more subtle effects of the final-state interaction.
↳ hep-phhep-exnucl-thFront.Phys.(Beijing)(2023)·13 citations
09
Medium modification of singly heavy baryons in a pion-mean field approach
Nam-Yong Ghim🇰🇷 · Hyun-Chul Kim🇰🇷 · Ulugbek Yakhshiev🇰🇷 · Ghil-Seok Yang🇰🇷
We investigate how the masses of singly heavy baryons undergo changes in nuclear matter. The mass spectrum of the singly heavy baryons was successfully described in a pion-mean field approach even with isospin symmetry breaking, based on which we extend the investigation to the medium modification of the singly heavy baryons. Since all dynamical parameters were determined by explaining the mass spectrum of the SU(3) light and singly heavy baryons in free space, we can directly implement the density-dependent functionals for the dynamical parameters, of which the density dependence was already fixed by reproducing the bulk properties of nuclear matter and medium modification of the SU(3) light baryons. We predict and discuss the density dependence of the masses of the singly heavy baryons.
↳ hep-phnucl-thPRD(2023)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE