We propose a new, rapidly convergent shape parametrization, the so-called Fourier-over-spheroid (FoS) approach, to model fission of heavy nuclei. Four collective coordinates are used to characterize the shape of the fissioning system: its elongation, left-right asymmetry, neck size, and nonaxiality. The potential energy landscape is computed within the macroscopic-microscopic approach, on the top of which the multidimensional Langevin equation is solved to describe the dynamics. Charge equilibration at scission and deexcitation of the primary fragments after scission are further considered. The model gives access to a wide variety of observables, including fission fragments' mass, charge, and kinetic energy yields, fragment mean $N/Z$ and postscission neutron multiplicities, and, importantly, their correlations. The latter are crucial to unravel the complexity of the fission process. The parameters of the model were tuned to reproduce experimental observation from thermal neutron-induced fission of ${}^{235}\mathrm{U}$, and next used to discuss the transition from the asymmetric to symmetric fission along the Fm isotopic chain.

We have systematically studied the connection (correspondence) between hadrons and their quark-component nuclear modification factors and the flavor (mass) ordering at both parton and hadron levels in nucleus-nucleus collisions at energies available at the CERN Large Hadron Collider, using the paciae model. It turns out that the correspondence and the mass ordering generally hold, irrespective of the rapidity, centrality, reaction energy, and collision system size. The nuclear modification factors of hadrons in the final hadronic state show clear mass ordering, which should be studied further both theoretically and experimentally.

Molecular dynamics simulations are performed for a finite nonrelativistic system of particles with Lennard-Jones potential. We study the effect of liquid-gas mixed phase on particle number fluctuations in coordinate subspace. A metastable region of the mixed phase, the so-called nucleation region, is analyzed in terms of a noninteracting cluster model. Large fluctuations due to spinodal decomposition are observed. They arise due to the interplay between the size of the acceptance region and that of the liquid phase. These effects are studied with a simple geometric model. The model results for the scaled variance of particle number distribution are compared with those obtained from the direct molecular dynamic simulations.

We construct a physics-agnostic approach to the neutron star (NS) equation of state (EoS) based on a sound speed model, which connects both low-density information from nuclear theory and high-density constraints from perturbative quantum chromodynamics (pQCD). Using this approach, we study the impact of pQCD calculations on NS EoS that have been constrained by astrophysical observations. We find that pQCD affects the EoS mainly beyond the densities realized in NS. Furthermore, we observe an interesting interplay between pQCD and astrophysical constraints, with pQCD preferring softer EoS for the heaviest NS while recent NICER observations suggest the EoS to be stiffer. We explore the sensitivity of our findings to pQCD uncertainties and study the constraining power of pQCD if future observations of heavy NS were to suggest radii larger than 13 km.

Background: Fission modes in superheavy nuclei are expected to be impacted by quantum shell effects. Similar shell effects may be present in quasifission reactions, acting to hinder the mass equilibration process in heavy-ion collisions.

Purpose: To investigate quasifission mechanisms in five different reactions forming ${}^{294}\mathrm{Og}$ as a compound nucleus and compare quasifission trajectories with predicted fission modes.

Methods: The potential energy surface (PES) of ${}^{294}\mathrm{Og}$ is calculated using the static Hartree-Fock approach with BCS pairing correlations. Quasifission trajectories for central collisions at various energies are studied with the time-dependent Hartree-Fock theory.

Results: The exit channel strongly depends on initial mass asymmetry and orientation, but it only exhibits small dependencies in the reaction energy. The ${}^{48}\mathrm{Ca}+{}^{246}\mathrm{Cf}$ reaction is affected by the PES topography, leading to either fusion or asymmetric fission. ${}^{126}\mathrm{Sn}+{}^{168}\mathrm{Er}$ reactions exhibit large total kinetic energies and compact scission configurations, which could be interpreted as an effect of the $Z=50$ spherical magic gap.

Conclusions: Quasifission trajectories can be interpreted in terms of the underlying PES for low excitation energies. Future investigations of quasifission with temperature- and angular-momentum-dependent PES could be considered.

Background: The absence of large fusion enhancement at sub-barrier energies was experimentally observed in the ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ system even though the ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ system has many positive $Q$-value neutron transfer channels, like the ${}^{124,132}\mathrm{Sn}+{}^{40}\mathrm{Ca}$ systems.

Purpose: We elucidate the roles of pairing dynamics in the enhancement and absence of enhancement of fusion reactions at near- and sub-barrier energies, as the dynamical pairing correlations were found recently to play an important role.

Method: The real space density-constrained time-dependent Hartree-Fock-Bogoliubov (rDC-TDHFB) method, proposed in Phys. Rev. C 105, 014613 (2022), is exploited to investigate ${}^{124}\mathrm{Sn}+{}^{40,48}\mathrm{Ca}$ and ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ reactions at near- and sub-barrier energies.

Results: The experimental data of ${}^{124}\mathrm{Sn}+{}^{40,48}\mathrm{Ca}$ and ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ fusion cross sections at near- and sub-barrier energies were finely reproduced when the pairing correlations were self-consistently considered in the microscopic simulations of collision dynamics. Pairing dynamics significantly raises the barrier height and reduces the fusion cross sections. The suppressions of fusion reactions at sub-barrier energies, as observed in the ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ reaction, are correlated with pairing energy sharing among projectilelike and targetlike subsystems in colliding nuclei, and also affect nucleon transfers.

Conclusions: Pairing correlations were found to play an important role in fusion reactions, and a large pairing energy sharing is strongly favored in the reactions lacking large fusion enhancements.

We derive the equations of quasiparticle random-phase approximation (QRPA) based on the finite amplitude method with the Hartree-Fock+Bardeen–Cooper–Schrieffer (HF+BCS) single-particle states, and calculate the magnetic dipole ($M1$) transition for deformed gadolinium isotopes. Our QRPA calculation shows both large spin-flip transitions in the 5 to 10 MeV excitation energy and the low energy orbital transition that would correspond to the $M1$ scissors mode observed in nuclear experiments. Then, we calculate neutron capture reactions based on the statistical Hauser-Feshbach theory with the photoabsorption cross sections of even-even nuclei given by QRPA. We find that the capture cross section is enhanced due to the contribution from the low energy $M1$ transition although the calculated capture cross section still underestimates the experimental data. This issue in the calculated capture cross section could be improved by uncertainties of the low energy $E1$ transition neglected in our QRPA calculation.

In this paper, we study the mixing of one-particle-one-hole projected states with the variation after projection (VAP) wave functions in an attempt to improve the approximation of this method. It turns out that, when minimizing only the lowest (yrast) energy with given spin and parity, the one-particle-one-hole projected states cannot be mixed into the converged VAP wave function, which is very similar to the situation of the Hartree-Fock method. However, if one minimizes the sum of several lowest energies with the same spin and parity, the one-particle-one-hole mixing can make some improvements to the VAP wave functions. We expect such one-particle-one-hole mixing may be useful in the calculations of the low-lying excited states in heavy nuclei with a large model space.

This Letter reports on the first measurements of transverse momentum dependent flow angle ${\mathrm{\Psi }}_n$ and flow magnitude $v_n$ fluctuations determined using new four-particle correlators. The measurements are performed for various centralities in Pb–Pb collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{{}_{NN}}}$ = 5.02 TeV with ALICE at the CERN Large Hadron Collider. Both flow angle and flow magnitude fluctuations are observed in the presented centrality ranges and are strongest in the most central collisions and for a transverse momentum $p_T>2\mathrm{GeV}/c$. Comparison with theoretical models, including iEBE-VISHNU, MUSIC, and AMPT, show that the measurements exhibit unique sensitivities to the initial state of heavy-ion collisions.

We present a new model for the creation of $J/\psi$ mesons in ultrarelativistic heavy ion collisions, which allows one to follow the individual heavy quarks from their creation until the detector through the quark-gluon plasma, which is formed in these collisions and described by the EPOS2 event generator. The $c$ and $\overline{c}$ quarks interact via a potential, based on results of lattice gauge calculations. The annihilation and creation of $J/\psi$ is described by a density matrix approach whose time evolution is studied in the expanding system. The comparison with PbPb data at $\sqrt{s}=5.02$ TeV shows that this model can describe simultaneously the nuclear modification factor $R_{AA}$ and the elliptic flow $v_2$ of the $J/\psi$ at low transverse momentum. Perspectives for further improvement are discussed.

This paper calculates the elastic form factors for nucleons based on generalized parton distributions using an extended new ansatz introduced in Phys. Rev. C 105, 025202 (2022). Different parton distribution functions (PDFs) are considered, and modifications are made to the free parameters of the new ansatz. The obtained results are systematically compared among the combinations of different PDFs and ansatzes for high ranges of momentum transfer, with $-t<35{\mathrm{GeV}}^{-2}$. The minimum suitable parameters are used to parametrize the model. After obtaining the form factors, we proceed to compute the electric radius and the transversely unpolarized densities for the nucleon. In addition, we derive the PDFs that depend on the impact parameter. Finally, we analyze the results by comparing them with the findings from other research and experimental data.

Collisions with oxygen ions at the CERN Large Hadron Collider (LHC) opens the possibility of investigating the description of the QCD dynamics in an unexplored regime, complementary to those performed in $pp, p\mathrm{Pb}$, and PbPb collisions. In this paper we estimate the exclusive $\rho$ and $J/\mathrm{\Psi }$ photoproduction in ultraperipheral $p\mathrm{O}$ and $\mathrm{OO}$ collisions at the LHC using the color dipole formalism and considering distinct models for the dipole-target scattering amplitude and different approaches for the modeling of the vector meson wave function. We present our predictions for the rapidity and transverse momentum distributions, as well as for the total cross sections considering the rapidity ranges covered by the ALICE and LHCb detectors. Such results indicate that a future experimental analysis of these final states is feasible and that its study can be useful to improve our understanding of the QCD dynamics at high energies.

Transverse wobbling was investigated in the ${}^{151}\mathrm{Eu}$ nucleus by populating the excited states using ${}^{148}\mathrm{Nd}({}^7\mathrm{Li}$, $4\mathrm{n}){}^{151}\mathrm{Eu}$ at a beam energy of 30 MeV. Three new interconnecting transitions have been placed between the two negative parity bands. The M1/E2 character of the interconnecting $\mathrm{\Delta }I=1$ transitions between the negative parity bands was extracted from the mixing ratios using the $R_{\mathrm{DCO}}$ and linear polarization method. The spin and parity of the states of different bands have also been assigned. The dominant E2 character of the interlinking transitions between the yrast and first phonon wobbling band and the dominant M1 character between the yrast band and its signature partner band indicate the presence of transverse wobbling in the ${}^{151}\mathrm{Eu}$ nucleus. It is further demonstrated that the triaxial projected shell model approach describes the observed experimental properties.

The high-spin states in ${}^{61}\mathrm{Ni}$ have been studied using the fusion evaporation reaction, ${}^{50}\mathrm{Ti}({}^{14}\mathrm{C},3\mathrm{n}){}^{61}\mathrm{Ni}$ at an incident beam energy of 40 MeV. A Compton suppressed multi-HPGe detector setup, consisting of six clover detectors and three single-crystal HPGe detectors, was used to detect the de-exciting $\gamma$ rays from the excited states. The level scheme has been extended up to an excitation energy of 12.8 MeV and a tentative $J^{\pi }=35/2^{+}$. The low-lying negative parity levels are found to be generated by single-particle excitation within the $fp$ shell and also excitations to the $g_{9/2}$ orbitals as explained well with shell model calculations using the $\mathrm{GXPF1Br}+V_{\text{MU}}$ (modified) interaction. Two rotational structures of regular E2 sequences with small to moderate axial deformation have been established at higher excitation energy. Most interestingly, two sequences of M1 transitions are reported for the first time and described as magnetic rotational bands. The shears mechanism for both the bands can be described satisfactorily by the geometrical model. The shell model calculation involving the cross shell excitation beyond the $fp$ shell well reproduce the M1 and E2 sequences. The shell model predicted $B\left(M1\right)$ values for the magnetic rotational band B1 show the decreasing trend with spin as expected with closing of the shears.

Cosmic-ray muons produce various radioisotopes when passing through material. These spallation products can be backgrounds for rare event searches such as in solar neutrino, double-$\beta$ decay, and dark matter search experiments. The KamLAND-Zen experiment searches for neutrinoless double-$\beta$ decay in 745 kg of xenon dissolved in liquid scintillator. The experiment includes dead-time-free electronics with a high efficiency for detecting muon-induced neutrons. The production yields of different radioisotopes are measured with a combination of delayed coincidence techniques, newly developed muon reconstruction, and xenon spallation identification methods. The observed xenon spallation products are consistent with results from the fluka and geant4 simulation codes.

Within the framework of the dinuclear system model, the preequilibrium emission of neutron, proton, deuteron, triton, ${}^3\mathrm{He}$, $\alpha$, ${}^6\mathrm{Li}$, ${}^7\mathrm{Li}$, ${}^8\mathrm{Be}$, and ${}^9\mathrm{Be}$ in the transfer reactions of ${}^{12}\mathrm{C}$ $+$ ${}^{209}\mathrm{Bi}$, ${}^{40,48}\mathrm{Ca}+{}^{238}\mathrm{U}$, ${}^{238}\mathrm{U}+{}^{238}\mathrm{U}$, and ${}^{238}\mathrm{U}+{}^{248}\mathrm{Cm}$ has been systematically investigated. The production rate, kinetic energy spectra, and emission angular distribution are calculated. It is found that the preequilibrium emission mechanism is associated with the reaction system and beam energy. The preequilibrium cross sections of proton, deuteron, triton, and alpha are comparable in magnitude. The reaction with ${}^{40}\mathrm{Ca}$ is favorable for the cluster emission in comparison with ${}^{48}\mathrm{Ca}$ on ${}^{238}\mathrm{U}$ at the near barrier energy. A broad angular distribution of the preequilibrium cluster is found in the heavy systems ${}^{238}\mathrm{U}+{}^{238}\mathrm{U}$ and ${}^{238}\mathrm{U}+{}^{248}\mathrm{Cm}$. The method is also possible for the weakly bound nuclei induced reactions. Future experiments are discussed for the preequilibrium cluster measurements.

A measurement of the production of vector bottomonium states, $\Upsilon \left(\text{1S}\right)$, $\Upsilon \left(\text{2S}\right)$, and $\Upsilon \left(\text{3S}\right)$, in $\mathrm{Pb}+\mathrm{Pb}$ and $pp$ collisions at a center-of-mass energy per nucleon pair of 5.02 TeV is presented. The data correspond to integrated luminosities of $1.38{\text{nb}}^{-1}$ of $\mathrm{Pb}+\mathrm{Pb}$ data collected in 2018, $0.44{\text{nb}}^{-1}$ of $\mathrm{Pb}+\mathrm{Pb}$ data collected in 2015, and $0.26{\text{fb}}^{-1}$ of $pp$ data collected in 2017 by the ATLAS detector at the Large Hadron Collider. The measurements are performed in the dimuon decay channel for transverse momentum $p_{\text{T}}^{\mu \mu }<30\mathrm{GeV}$, absolute rapidity $|y^{\mu \mu }|<1.5$, and $\mathrm{Pb}+\mathrm{Pb}$ event centrality 0–80%. The production rates of the three bottomonium states in $\mathrm{Pb}+\mathrm{Pb}$ collisions are compared with those in $pp$ collisions to extract the nuclear modification factors as functions of event centrality, $p_{\text{T}}^{\mu \mu }$, and $|y^{\mu \mu }|$. In addition, the suppression of the excited states relative to the ground state is studied. The results are compared with theoretical model calculations.

The nuclear structure orbital entanglement entropy of short range correlation (SRC) is calculated based on the nuclear scale separation, specifically, the entanglement between the SRC orbitals and the rest of the system. It should be stressed that this is a single nucleon and not a pair entanglement entropy between the proton and neutron. The entanglement arises from the probability for a nucleon to occupy a momentum state above the Fermi momentum. The momentum space of the nucleus separates into two parts such that nucleons can occupy the mean-field part of the wave function, i.e., the Fermi sea (FS) and separately the high-momentum SRC part. The orbital entropy obtained is between these two parts where essentially two momentum subspaces are defined, one containing all the low momentum FS states and the other containing the high-momentum part as a SRC “orbital” state. For the calculation of the decoupling of low and high momenta which was established by the similarity normalization group the SRC is employed and viewed as a further orbital which can be multiply occupied. Since the probability of the occupation of a single SRC is given by the nuclear contact a simple general expression of the orbital entanglement entropy for SRC by employing the generalized contact formalism is obtained. This general formula for the SRC orbital entanglement entropy of a nuclear structure in terms of the nuclear contact allows one to obtain the scaling of the entropy in terms of the mass number, $A$. From this formula it is evident that, unlike the entanglement entropy of many quantum systems which scales with the surface area, the orbital entanglement entropy associated with the SRC in large nuclei is linearly dependent on $A$, i.e., it is shown to be extensive.

We report on empirical parametrizations of longitudinal and transverse nuclear excitation electromagnetic form factors in ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$. We extract the contribution of nuclear excitations to the normalized inelastic Coulomb sum rule $\left[S_L\left(\mathbf{q}\right)\right]$ as a function of momentum transfer $\mathbf{q}$ and find that it is significant $(0.29\pm 0.030$ at $\mathbf{q}=\mathbf{0}.\mathbf{22}\mathbf{\text{GeV}})$. The total contributions of nuclear excitations to $S_L\left(\mathbf{q}\right)$ in ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ are found to be equal within uncertainties. Since the cross sections for nuclear excitations are significant, the radiative tails from nuclear excitations should be included in precise calculations of radiative corrections to quasielastic electron scattering at low $\mathbf{q}$ and deep-inelastic electron scattering at large energy transfers $\nu$. The parametrizations also serve as a benchmark in testing theoretical modeling of cross sections for excitation of nuclear states in electron and neutrino interactions on nuclear targets at low energies.

We study theoretically production spectra with a ${\mathrm{\Sigma }}^{-}$ hyperon via $({\pi }^{-},K^{+})$ reactions on ${}^{12}\mathrm{C}$, ${}^{28}\mathrm{Si}$, ${}^{58}\mathrm{Ni}$, ${}^{115}\mathrm{In}$, and ${}^{209}\mathrm{Bi}$ targets, using the Green's function method in the framework of a distorted-wave impulse approximation with the optimal Fermi averaging for an elementary ${\pi }^{-}p\to K^{+}{\mathrm{\Sigma }}^{-}t$ matrix. Adopting distorted waves obtained by solving a Klein-Gordon equation for ${\pi }^{-}$ and $K^{+}$ mesons, we improve and update the calculated spectra of ${\mathrm{\Sigma }}^{-}$ production cross sections comprehensively in comparison with the data of the KEK-E438 experiment. We use several $\mathrm{\Sigma }$-nucleus (optical) potentials that are determined by fits to the ${\mathrm{\Sigma }}^{-}$ atomic data and that take into account the energy dependence arising from the nuclear excitation via $\mathrm{\Sigma }N\to \mathrm{\Sigma }N$ scatterings with a $\mathrm{\Sigma }$ hyperon effective mass. The results show that the absolute values and the shapes of these calculated spectra are in excellent agreement with those of the data, so that a mass-number dependence of integrated cross sections on the light-to-heavy targets is well reproduced in our calculations. It confirms that the $\mathrm{\Sigma }$-nucleus potentials having a repulsion inside the nuclear surface and an attraction outside the nucleus with a sizable absorption are favored in reproducing the data of the nuclear $({\pi }^{-},K^{+})$ spectra and the ${\mathrm{\Sigma }}^{-}$ atomic x ray simultaneously, whereas it is still difficult to determine the radial distribution of the $\mathrm{\Sigma }$-nucleus potential inside the nucleus and its strength at the center.