Nuclear Theory·nucl-th

Monday·July 8, 2024

20 papers—7 primary·13 cross-listed

01
Quantum Monte Carlo calculations of magnetic form factors in light nuclei
G. Chambers-Wall🇺🇸 · A. Gnech🇺🇸 · G. B. King🇺🇸 · S. Pastore🇺🇸 · M. Piarulli🇺🇸 · R. Schiavilla🇺🇸 · R. B. Wiringa🇺🇸
We present Quantum Monte Carlo calculations of magnetic form factors in $A = 6 - 10$ nuclei, based on Norfolk two- and three-nucleon interactions, and associated one- and two-body electromagnetic currents. Agreement with the available experimental data for $^{6}$ Li, $^{7}$ Li, $^{9}$ Be and $^{10}$ B up to values of momentum transfer $q \sim 3$ fm $^{- 1}$ is achieved when two-nucleon currents are accounted for. We present a set of predictions for the magnetic form factors of $^{7}$ Be, $^{8}$ Li, $^{9}$ Li, and $^{9}$ C. In these systems, two-body currents account for $\sim 40 - 60%$ of the total magnetic strength. Measurements in any of these radioactive systems would provide valuable insights on the nuclear magnetic structure emerging from the underlying many-nucleon dynamics. A particularly interesting case is that of $^{7}$ Be, as it would enable investigations of the magnetic structure of mirror nuclei.
nucl-thPRL(2024)·19 citations
02
Examination of the evidence for a proton halo in $^{22}$ Al
K. Y. Zhang · C. Pan · Sibo Wang
More and more halo nuclei or candidates have been identified or suggested in experiments in recent years. It was declared that the halo structure of $^{22}$ Al is revealed by the large isospin asymmetry in $^{22}$ Si/ $^{22}$ O mirror Gamow-Teller transitions [Phys. Rev. Lett. 125, 192503 (2020)]. We highlight that a significant mirror asymmetry already exists between wave functions of the likely unbound nucleus $^{22}$ Si and the doubly-magic nucleus $^{22}$ O, which largely explains the observed asymmetry in the transitions. Furthermore, these transitions involve only the $1^{+}$ excited states of the daughter nuclei $^{22}$ Al and $^{22}$ F. The $1^{+}$ state of $^{22}$ Al cannot be considered a halo state due to its proton-unbound nature. An analysis of the spin-parity suggests that a weakly bound $2 s_{1/2}$ valence proton in the ground state of $^{22}$ Al is improbable. To investigate the shell structure for the ground state of $^{22}$ Al, we employ the state-of-the-art deformed and triaxial relativistic Hartree-Bogoliubov theories in continuum. We find that a small $s$ -wave component of $5%$ appears for the weakly bound valence proton in $^{22}$ Al only when triaxial deformation is considered. While the examination of densities and rms radii indicates that this small $s$ -wave component is insufficient to form a discernible proton halo in $^{22}$ Al, slightly larger $2 s_{1/2}$ occupations have been reported in other recent theoretical results. The question of how many low- $ℓ$ components are sufficient to form a proton halo in the presence of the Coulomb barrier remains open. Thus, future measurements of reaction or interaction cross sections and momentum distributions of breakup fragments are highly desirable to verify whether $^{22}$ Al is a halo nucleus.
nucl-thnucl-exPRC(2024)·25 citations
03
Interplay of single-particle and collective modes in the $^{12}$ C(p,2p) reaction near 100 MeV
A. Deltuva · E. Cravo · R. Crespo · D. Jurčiukonis
The $^{12}$ C(p,2p) $^{11}$ B reaction at $E_{p} = 98.7$ MeV proton beam energy is analyzed using a rigorous three-particle scattering formalism extended to include the internal excitation of the nuclear core or residual nucleus. The excitation proceeds via the core interaction with any of the external nucleons. We assume the $^{11}$ B ground and low-lying excited states [ $\frac{3}{2}^{-}$ (0.0 MeV), $\frac{5}{2}^{-}$ (4.45 MeV), $\frac{7}{2}^{-}$ (6.74 MeV)] and the excited states [ $\frac{1}{2}^{-}$ (2.12 MeV), $\frac{3}{2}^{-}$ (5.02 MeV)] to be members of $K = \frac{3}{2}^{-}$ and $K = \frac{1}{2}^{-}$ rotational bands, respectively. The dynamical core excitation results in a significant cross section for the reaction leading to the $\frac{5}{2}^{-}$ (4.45 MeV) excited state of $^{11}$ B that cannot be populated through the single-particle excitation mechanism. The detailed agreement between the theoretical calculations and data depends on the used optical model parametrizations and the kinematical configuration of the detected nucleons.
nucl-thPLB(2024)·2 citations
04
Role of clustered nuclear geometry in particle production through p-C and p-O collisions at the Large Hadron Collider
Aswathy Menon K R🇮🇳 · Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳
Long-range multi-particle correlations in heavy-ion collisions have shown conclusive evidence of the hydrodynamic behavior of strongly interacting matter and are associated with the final-state azimuthal momentum anisotropy. In small collision systems, azimuthal anisotropy can be influenced by the hadronization mechanism and residual jet-like correlations. Thus, one of the motives of the planned p--O and O--O collisions at the LHC and RHIC is to understand the origin of small system collectivity. As the anisotropic flow coefficients ( $v_{n}$ ) are sensitive to the initial-state effects including nuclear shape, deformation, and charge density profiles, studies involving $^{12}$ C and $^{16}$ O nuclei are transpiring due to the presence of exotic $α$ ( $^{4}$ He) clusters in such nuclei. In this study, for the first time, we investigate the effects of nuclear $α$ --clusters on the azimuthal anisotropy of the final-state hadrons in p--C and p--O collisions at $s_{NN} = 9.9$ ~TeV within a multi-phase transport model framework. We report the transverse momentum ( $p_{T}$ ) and pseudorapidity ( $η$ ) spectra, participant eccentricity ( $ϵ_{2}$ ) and triangularity ( $ϵ_{3}$ ), and estimate the elliptic flow ( $v_{2}$ ) and triangular flow ( $v_{3}$ ) of the final-state hadrons using the two-particle cumulant method. These results are compared with a model-independent Sum of Gaussians (SOG) type nuclear density profile for $^{12}$ C and $^{16}$ O nuclei.
nucl-thhep-exhep-phnucl-exEPJA(2025)·10 citations
05
Probing the equilibration of the QCD matter created in heavy-ion collisions with dileptons
Xiang-Yu Wu🇨🇦 · Lipei Du🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦
A systematic study of intermediate invariant mass dilepton production in Pb+Pb collisions at $s_{N N} = 5.02$ TeV is performed, using next-to-leading-order (NLO) thermal QCD dilepton emission rates with a multistage dynamical approach which includes event-by-event IP-Glasma initial conditions, relativistic viscous fluid dynamics, and a hadronic afterburner. Considering dilepton yield and anisotropic flow, special attention is paid to the out-of-equilibrium aspects, both thermal and chemical, and to the contribution of the Drell-Yan process. The relative contribution of each of those different channels to dilepton observables is calculated and discussed.
nucl-thhep-phnucl-exPRC(2024)·23 citations
06
Study of the neutrino-oxygen cross sections of the charged-current reaction 16O( $ν ˉ_{e}, e^{+}$ )16N(0 MeV, $2^{-}$ ) and the neutral-current reaction 16O( $ν, ν$ ')16O(12.97/12.53 MeV, $2^{-}$ ), producing high-energy gamma rays
Makoto Sakuda🇯🇵 · Toshio Suzuki🇯🇵 · Ken'ichiro Nakazato🇯🇵 · Hideyuki Suzuki🇯🇵
In the previous work, we discussed the cross section and the detection of 4.4-MeV $γ$ rays produced in the neutrino neutral-current (NC) reaction $^{16}$ O( $ν, ν^{'}$ ) $^{16}$ O(12.97 MeV and 12.53 MeV, $2^{-}$ ) in a water Cherenkov detector at the low energy below 100 MeV. In this report, we further investigated both the charged-current (CC) reaction $^{16}$ O( $ν ˉ_{e}, e^{+}$ ) $^{16}$ N(0 MeV, $2^{-}$ ) and the NC reaction $^{16}$ O( $ν, ν^{'}$ ) $^{16}$ O(12.97 MeV and 12.53 MeV, $2^{-}$ ), producing high-energy $γ$ rays, in which the more solid identification of the reactions can be applied via the coincidence method.
nucl-thhep-phnucl-exPTEP(2024)·0 citations
07
Constraining the high-density behavior of nuclear symmetry energy with direct Urca processes
Olfa Boukari · Tuhin Malik · Aziz Rabhi · Constança Providência
The density dependence of the symmetry energy in relativistic mean-field models with density dependent couplings is discussed in terms of the possible opening of nucleonic direct Urca processes inside neutron stars, which induce a very rapid cooling of the star. The modification of the parametrization of the isospin channel of two models, DD2 and DDMEX, keeping the same isoscalar properties is considered and the implications are discussed. Within the models discussed it is not possible the onset of nucleonic direct Urca processes in stars with a mass below $\sim 1.6 M_{⊙}$ if chiral effective field theory constraints for neutron matter are imposed. A Bayesian inference calculation confirms the low probability that nucleonic direct Urca processes occur inside stars with masses below 1.8 $M_{⊙}$ , considering the isoscalar channel of the equation of state described by DD2 or DDMEX and the same symmetry energy at saturation. The lowest masses allowing direct Urca processes are associated with a slope of the symmetry energy above $60$ MeV and most likely a positive symmetry energy incompressibility. It is shown that the parametrization of the isospin channel proposed destroys the correlation between symmetry energy slope and incompressibility previously identified in several works.
nucl-thastro-ph.HEPRC(2024)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantum Monte Carlo calculations of magnetic form factors in light nuclei

Examination of the evidence for a proton halo in 22Al

Interplay of single-particle and collective modes in the 12C(p,2p) reaction near 100 MeV

Role of clustered nuclear geometry in particle production through p-C and p-O collisions at the Large Hadron Collider

Probing the equilibration of the QCD matter created in heavy-ion collisions with dileptons

Study of the neutrino-oxygen cross sections of the charged-current reaction 16O(νˉe​,e+)16N(0 MeV,2−) and the neutral-current reaction 16O(ν,ν')16O(12.97/12.53 MeV,2−), producing high-energy gamma rays

Constraining the high-density behavior of nuclear symmetry energy with direct Urca processes

Affiliations

Examination of the evidence for a proton halo in $^{22}$ Al

Interplay of single-particle and collective modes in the $^{12}$ C(p,2p) reaction near 100 MeV

Study of the neutrino-oxygen cross sections of the charged-current reaction 16O( $ν ˉ_{e}, e^{+}$ )16N(0 MeV, $2^{-}$ ) and the neutral-current reaction 16O( $ν, ν$ ')16O(12.97/12.53 MeV, $2^{-}$ ), producing high-energy gamma rays