Stellar abundances of cerium are of high current interest based both on observations and theoretical models, especially with regard to the neutron-magic ${}^{140}\mathrm{Ce}$ isotope. A large discrepancy of $s$-process stellar models relative to cerium abundance observed in globular clusters was highlighted, pointing to possible uncertainties in experimental nuclear reaction rates. In this work, the stellar neutron capture cross section of the stable cerium isotopes ${}^{136}\mathrm{Ce}$, ${}^{138}\mathrm{Ce}$, ${}^{140}\mathrm{Ce}$, and ${}^{142}\mathrm{Ce}$, were remeasured. A ${}^{\text{nat}}\mathrm{Ce}$ sample was irradiated with quasi-Maxwellian neutrons at $kT=34.2$ keV using the ${}^7\mathrm{Li}(p,n)$ reaction. The neutron field with an intensity of $3\text{–}5\times {10}^{10}$ n/s was produced by irradiating the liquid-lithium target (LiLiT) with a mA proton beam at an energy (1.92 MeV) just above the threshold at Soreq Applied Research Accelerator Facility (SARAF). The activities of the ${}^{\text{nat}}\mathrm{Ce}$ neutron capture products were measured using a shielded high purity germanium detector. Cross sections were extracted relative to that of the ${}^{197}\mathrm{Au}(n,\gamma )$ reaction and the Maxwellian-averaged cross section (MACS) of the Ce isotopes were derived. The MACS values extracted from this experiment are generally consistent with previous measurements and show for ${}^{140}\mathrm{Ce}$ a value $\approx 15$% smaller than most recent experimental values.

In this work, we propose a novel method for calculating the occupation probability in the Pauli blocking of the quantum molecular dynamics type models. This method refines the description of the Pauli blocking ratio in the nuclear matter and that in the finite nucleus. The influence of the new Pauli blocking method on the heavy ion collisions observables, such as the charge distribution, the free neutron to proton yield ratios, and the extracted physical quantities, such as the in-medium nucleon-nucleon cross sections, are investigated. For the extracted in-medium nucleon-nucleon cross sections, our results show that it will be enhanced 1.1–2.5 times than that with the conventional Pauli blocking method at the beam energy less than 150 MeV/u, which highlights the importance of a refined Pauli blocking method for developing an advanced transport model to describe complex heavy ion collisions.

The interiors of neutron stars contain matter at the highest densities realized in our Universe. Interestingly, theoretical studies of dense matter, in combination with the existence of two-solar-mass neutron stars, indicate that the speed of sound $c_s$ has to increase to values well above the conformal limit ($c_s^2=1/3$) before decreasing again at higher densities. The decrease could be explained by either a strong first-order phase transition or a crossover transition from hadronic to quark matter. The latter scenario leads to a pronounced peak in the speed of sound, reaching values above the conformal limit, naturally explaining the inferred behavior. In this work, we use the nuclear-physics multimessenger astrophysics (NMMA) framework to compare predictions of the quarkyonic matter model with astrophysical observations of neutron stars, with the goal of constraining model parameters. Assuming quarkyonic matter to be realized within neutron stars, we find that there can be a significant amount of quarks inside the cores of neutron stars with masses in the two-solar-mass range, amounting to up to $\approx 0.13M_{\odot }$, contributing $\approx 5.9\%$ of the total mass. Furthermore, for the quarkyonic matter model investigated here, the radius of a $1.4M_{\odot }$ neutron star would be $13.{44}_{-1.54}^{+1.69}(13.{54}_{-1.04}^{+1.02})\mathrm{km}$, at $95\%$ credibility, without (with) the inclusion of AT2017gfo.

The possibility of using the generator coordinate method (GCM) using hybrid quantum-classical algorithms with reduced quantum resources is discussed. The task of preparing the basis states and calculating the various kernels involved in the GCM is assigned to the quantum computer, while the remaining tasks, such as finding the eigenvalues of a many-body problem, are delegated to classical computers for post-processing the generated kernels. This strategy reduces the quantum resources required to treat a quantum many-body problem. We apply the method to the Lipkin model. Using the permutation symmetry of the Hamiltonian, we show that, ultimately, only two qubits is enough to solve the problem regardless of the particle number. The classical computing post-processing leading to the full energy spectrum can be made using standard generalized eigenvalues techniques by diagonalizing the so-called Hill-Wheeler equation. As an alternative to this technique, we also explored how the quantum state deflation method can be adapted to the GCM problem. In this method, variational principles are iteratively designed to access the different excited states with increasing energies. The methodology proposed here is successfully applied to the Lipkin model with a minimal size of two qubits for the quantum register. The performances of the two classical post-processing approaches with respect to the statistical noise induced by the finite number of measurements and quantum devices noise are analyzed. Very satisfactory results for the full energy spectra are obtained once noise corrections techniques are employed.

We derive stochastic equations of motion of hydrodynamic fluctuations, performing perturbative expansion of the energy-momentum conservation equations around the boost invariant solution in a one-dimensional expanding system. In the course of derivation, we do not assume any specific forms of constitutive equations for shear stress tensor ${\pi }^{\mu \nu }$ and bulk pressure $\mathrm{\Pi }$. Therefore, the framework enables us to employ any constitutive equations beyond the Navier-Stokes theory which satisfy the causality. Employing Israel-Stewart equations as examples of the constitutive equations, we demonstrate the dynamics of causal hydrodynamic fluctuations in $(1+1)$-dimensional Milne coordinates on an event-by-event basis. We observe that the structure of energy density and flow rapidity fluctuations is almost frozen in the early stage of the expansion. Two-point correlations of energy density fluctuations turn out to be closely related to the properties of the medium, such as sound velocity, viscosity, and relaxation time. Furthermore, we show that two-particle correlation functions of final hadrons after freeze-out inherit correlations of thermodynamic variables and flow rapidity. This opens a new door for an analysis of transport properties of the medium produced in relativistic heavy ion collisions.

In beam $\gamma$-ray spectroscopic investigations of the ${}^{90}\mathrm{Nb}$ nucleus have been explored by employing the ${}^{76}\mathrm{Ge}({}^{19}\mathrm{F},5n){}^{90}\mathrm{Nb}$ reaction. Twenty-eight new transitions belonging to ${}^{90}\mathrm{Nb}$ have been identified and placed in the proposed level scheme through the analysis of $\gamma \text{−}\gamma$ coincidence spectra. Shell model calculations have been performed in the restricted $\pi (p_{3/2},f_{5/2},p_{1/2},g_{9/2})\otimes \nu (p_{1/2},g_{9/2},d_{5/2},g_{7/2})$ configuration space, and compared to the new level scheme. According to the calculations, the newly observed 2614.6 keV $\gamma$ ray depopulating the $\left({15}_3^{+}\right)$ level at 4421.2 keV is explicated as the breakup of the $N=50$ neutron closed shell, while the $\gamma$ ray with 2774.0 keV feeding the $\left({13}_1^{-}\right)$ level at 2812.9 keV is interpreted as protons excitation across the $Z=38$ subshell.

Within the framework of the isospin-dependent quantum molecular dynamics (IQMD) model, we simulate the semiperipheral collisions of neutron-rich Ca, Mg, and Ne isotopes on ${}^{12}\mathrm{C}$ target at 50 MeV/nucleon. Different neutron-skin thicknesses $\left(S_n\right)$ of projectiles are obtained by adjusting the neutron diffuseness parameter in the droplet model. It is suggested that in both initial and final states, the difference of momentum between neutrons and protons $\left[\mathrm{\Delta }P\right(n-p\left)\right]$ decreases linearly with the increase of $S_n$. The similar correlation exists between $S_n$ and the peak position of the momentum spectrum of neutrons $\left(g_1\right)$. Moreover, the yield ratio of neutrons to protons $\left[R\right(n/p\left)\right]$ is proportional to $S_n$ and $R(n/p)$ with lower momentum is more sensitive to $S_n$. The above analyses are also applied to the triton and ${}^3\mathrm{He}$, which displays some limitations of their dependence on $S_n$. Therefore, $\mathrm{\Delta }P(n-p)$, $g_1$, and $R(n/p)$ can be taken as general experimental observables to extract information on $S_n$.

Multinucleon transfer (MNT) reactions have received increasing interest in the synthesis of neutron-rich nuclei due to the distinct limitations of other reactions, particularly in the $N=126$ region, which represents the last waiting point of astrophysical nucleosynthesis. However, it is still a challenging endeavor to describe the MNT process between heavy nuclei. In this study, we develop a theoretical framework that couples the Langevin dynamics iteratively with the master equation, which is based on the HICOL model (CLIM-H). The random transfer process is achieved by solving the master equation using the Monte Carlo method, where the parametric transfer probability with a $Q$ window is employed. The isotope distributions for ${}^{58,64}\mathrm{Ni}+{}^{208}\mathrm{Pb}$, as well as the angular and isotope distributions of the recently measured ${}^{206}\mathrm{Pb}+{}^{118}\mathrm{Sn}$, could be generally reproduced based on this method. Contrary to previous theoretical predictions which show a high production cross section of $N=126$ nuclei, current calculations do not reveal appreciable cross sections. The distinguishing characteristic of this approach is its ability to generate not only the mass distribution but also the charge distribution self-consistently, which could provide references for many other studies using the multidimensional Langevin equation considering only the mass asymmetry degree of freedom.

The current investigation focuses on detailed analysis of the anchor-based optimization approach (ABOA), its comparison with alternative global fitting protocols and on the global analysis of the truncation of basis effects in the calculation of binding energies. It is shown that ABOA provides a solution which is close to that obtained in alternative approaches but at small portion of their computational time. The application of a softer correction function after few initial iterations of ABOA stabilizes and speeds up its convergence. The numerical errors in the calculation of binding energies related to the truncation of bosonic and fermionic bases have been globally investigated with respect of asymptotic values corresponding to the infinite basis in the framework of covariant density functional theory (CDFT). These errors typically grow with the increase of the mass and deformation of the nuclei. To reduce such errors in bosonic sector below 10 keV for almost all nuclei with proton number $Z<120$ one should truncate the bosonic basis at $N_B=28$ instead of presently used $N_B=20$. The reduction of the errors in binding energies due to the truncation of the fermionic basis in CDFT is significantly more numerically costly. For the first time it is shown that the pattern and the speed of the convergence of binding energies as a function of the size of fermionic basis given by $N_F$ depend on the type of covariant energy density functional. The use of explicit density dependence of the meson-nucleon coupling constants or point couplings slows substantially the speed of convergence of binding energies as a function of $N_F$. The present paper clearly indicates the need for accounting of infinite basis corrections for accurate calculation of binding energies and for fitting more precise next-generation covariant energy density functionals: note that such corrections are neglected in the present generation of the functionals. A procedure for finding the asymptotic values of binding energies is suggested in the present paper: it allows better control of numerical errors.

In this paper we study the structure of even-even Ba isotopes with neutron number $N=84–90$ within the framework of nucleon-pair approximation of the shell model. We use a phenomenological Hamiltonian, which includes single-particle energies, monopole, quadrupole, and octupole pairing energies, as well as quadrupole-quadrupole and octupole-octupole interactions. Our calculated energy levels and $B\left(E2\right)$ values are in good agreement with experimental data. The alternating parity doublets are well reproduced by considering $F^{-}$ nucleon pairs with spin-three and negative parity, which demonstrates the importance of $F^{-}$ pair in octupole deformation. The octupole-octupole interaction is found to favor stronger $B\left(E3\right)$ transitions and suppress $B\left(E2\right)$ transitions in the low-lying states of nuclei in these even-even Ba isotopes.

We report a high precision measurement of electron beam polarization using Compton polarimetry. The measurement was made in experimental Hall A at Jefferson Lab during the CREX experiment in 2020. A total uncertainty of $dP/P=0.36\%$ was achieved detecting the back-scattered photons from the Compton scattering process. This is the highest accuracy in a measurement of electron beam polarization using Compton scattering ever reported, surpassing the groundbreaking measurement from the SLD Compton polarimeter. Such uncertainty reaches the level required for the future flagship measurements to be made by the MOLLER and SoLID experiments.

Based on the beyond-mean-field Skyrme-Hartree-Fock model, we investigate the energy spectra and possible cluster structure in ${}^{12}\mathrm{C}$ and its $\mathrm{\Lambda }$ hypernucleus ${}_{\mathrm{\Lambda }}{}^{13}\mathrm{C}$. The up-to-date Skyrme-type $N\mathrm{\Lambda }$ interaction SLL4 and the reduced $NN$ interaction SGII are employed. Low-lying energy spectra of ${}^{12}\mathrm{C}$, including the lowest five $0^{+}$ states, are predicted and discussed in detail, and found in good agreement with experimental results. The electric quadrupole transition rates and the monopole matrix elements between the $0^{+}$ states are also examined. Although typical cluster structures for the $0_2^{+}$ and $0_3^{+}$ states are absent, a linear-chain-like $3\alpha$ structure is found for the $0_4^{+}$ state. An energy spectrum including both the positive- and negative-parity levels is also given and structures of the corresponding hypernuclear states are discussed in detail. Impurity effects of a ${\mathrm{\Lambda }}_s$ or ${\mathrm{\Lambda }}_p$ hyperon on the nuclear core states of ${}_{\mathrm{\Lambda }}{}^{13}\mathrm{C}$ are demonstrated by the change of collective wave functions.

Low-lying excited levels in ${}^{116}\mathrm{Te}$ were studied by measuring level lifetimes with the recoil-distance Doppler-shift method in the ${}^{112}\mathrm{Sn}({}^{12}\mathrm{C},{}^8\mathrm{Be}){}^{116}\mathrm{Te}\alpha$-transfer reaction and angular correlations following the $\beta$ decay of ${}^{116}\mathrm{I}$. Both experiments were performed at the Cologne FN Tandem accelerator. Several new levels were discovered below 3.2 MeV excitation energy, spins and multipole mixing ratios were determined via angular correlations. Lifetimes were measured for the $2_1^{+}$, $0_2^{+}$, $2_2^{+}$, and $4_1^{+}$ and upper limits for lifetimes were determined for higher lying levels. The experimental findings are compared to calculations in the U(5) limit of the interacting boson model and are also discussed in the framework of shape coexistence which is expected in midshell Te isotopes.

Two-particle Bose–Einstein momentum correlation functions are studied for charged-hadron pairs in lead-lead collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. The data sample, containing $4.27\times {10}^9$ minimum bias events corresponding to an integrated luminosity of 0.607 ${\text{nb}}^{-1}$, was collected by the CMS experiment in 2018. The experimental results are discussed in terms of a Lévy-type source distribution. The parameters of this distribution are extracted as functions of particle pair average transverse mass and collision centrality. These parameters include the Lévy index or shape parameter $\alpha$, the Lévy scale parameter $R$, and the correlation strength parameter $\lambda$. The source shape, characterized by $\alpha$, is found to be neither Cauchy nor Gaussian, implying the need for a full Lévy analysis. Similarly to what was previously found for systems characterized by Gaussian source radii, a hydrodynamical scaling is observed for the Lévy $R$ parameter. The $\lambda$ parameter is studied in terms of the core-halo model.

Collective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the CERN Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle multiplicities comparable to peripheral Pb-Pb collisions. One of the possible signatures of collective behavior is the decrease of femtoscopic radii extracted from pion and kaon pairs emitted from high-multiplicity collisions with increasing pair transverse momentum. This decrease can be described in terms of an approximate transverse mass scaling. In the present work, femtoscopic analyses are carried out by the ALICE Collaboration on charged pion and kaon pairs produced in $pp$ collisions at $\sqrt{s}=13\mathrm{TeV}$ from the LHC to study possible collectivity in $pp$ collisions. The event-shape analysis method based on transverse sphericity is used to select for spherical versus jetlike events, and the effects of this selection on the femtoscopic radii for both charged pion and kaon pairs are studied. This is the first time this selection method has been applied to charged kaon pairs. An approximate transverse-mass scaling of the radii is found in all multiplicity ranges studied when the difference in the Lorentz boost for pions and kaons is taken into account. This observation does not support the hypothesis of collective expansion of hot and dense matter that should only occur in high-multiplicity events. A possible alternate explanation of the present results is based on a scenario of common emission conditions for pions and kaons in $pp$ collisions for the multiplicity ranges studied.

The question of how and which physical observables or thermodynamic parameters can best predict the onset of a possible phase transition in the inner crust of neutron stars remains largely unresolved. Using semiclassical Monte Carlo simulations, we investigate the isothermal compressibility and density fluctuations in a region of relevance to the dynamics of the inner crust. We show that the isothermal compressibility serves as a robust observable to characterize the transition from the nonuniform crust to the uniform core for proton fractions over 0.2. Moreover, we show explicitly how the two-component isothermal compressibility, computed using the Kirkwood-Buff theory, is directly connected to the fluctuations in the number density, recorded in the grand canonical ensemble by monitoring the number of particles in a small volume located at the center of the simulation box. That is, we compute mean-square particle fluctuations and compare them against the isothermal compressibility for different proton fractions. Although our results show that the mean-square particle fluctuations are proportional to the isothermal compressibility, the lack of a perfect correlation is attributed to the relatively small number of particles included in the simulations. The nonunity slope observed in the dimensionless isothermal compressibility—total nucleon fluctuation variance relationship suggests that the inner crust of neutron stars is composed of anisotropic and inhomogeneous matter.

Background: A systematic exploration of one-nucleon transfer reactions induced by the (${}^{18}\mathrm{O},{}^{19}\mathrm{F}$) and (${}^{18}\mathrm{O},{}^{17}\mathrm{O}$) reactions on different targets (${}^{12}\mathrm{C}, {}^{16}\mathrm{O}, {}^{27}\mathrm{Al}, {}^{40}\mathrm{Ca}, {}^{48}\mathrm{Ti}, {}^{76}\mathrm{Se}, {}^{116}\mathrm{Sn}$) is being performed at the Istituto Nazionale di Fisica Nucleare–Laboratori Nazionali del Sud (INFN-LNS) at beam energies higher than Coulomb barrier. A featured aspect is the adoption of a multichannel reaction approach, where several quasielastic processes are studied consistently from both the experiment and theory sides. Resembling the case of light-ion induced direct reactions, for which a large amount of data exists, the multichannel heavy-ion direct reaction is a powerful tool to characterize nuclear mean field as well as few-nucleon correlations in low-lying nuclear states. In this view, the study of different reaction mechanisms and nuclear structure models helps to characterize the nuclear wave functions and accurately scrutinize the parameters that control the uncertainties in the calculations of nuclear matrix elements (NMEs). In this context, special attention is recently paid to NMEs involved in second-order isotensor processes such as double charge exchange (DCE) and neutrinoless double beta ($0\nu \beta \beta$) decay.

Purpose: We perform the experiment and the data analysis based on theoretical models of one-nucleon transfer reactions induced by the ${}^{18}\mathrm{O}+{}^{76}\mathrm{Se}$ collision at energies above the Coulomb barrier in a multichannel approach. The ${}^{76}\mathrm{Se}$ nucleus attracts nowadays much interest since it is the daughter in the ${}^{76}\mathrm{Ge} \beta \beta$ decay, and the nuclear matrix elements involved in the ${}^{76}\mathrm{Se}_{\mathrm{g}.\mathrm{s}.}\to {}^{76}\mathrm{Ge}_{\mathrm{g}.\mathrm{s}.}$ and ${}^{76}\mathrm{Ge}_{\mathrm{g}.\mathrm{s}.}\to {}^{76}\mathrm{Se}_{\mathrm{g}.\mathrm{s}.}$ transitions are the same for time reversal symmetry. In particular, we intend to analyze transitions to low-lying excited states of the residual and ejectile nuclei in the ${}^{76}\mathrm{Se}({}^{18}\mathrm{O},{}^{19}\mathrm{F}){}^{75}\mathrm{As}$ one-proton pickup reaction at 275 MeV incident energy by measuring the cross section. An additional goal is to determine the role of the coupling channels in the measured cross sections, testing different model descriptions of the involved nuclear states.

Methods: Nuclear reactions induced by the ${}^{18}\mathrm{O}+{}^{76}\mathrm{Se}$ collision were measured at INFN-LNS using the MAGNEX large acceptance magnetic spectrometer for the detection of the ejectiles. The missing mass technique was used for the reconstruction of the reaction kinematics. The excitation energy spectrum and the differential cross section angular distributions were the key extracted observables. The experimental data were compared with theoretical calculations based on the distorted wave Born approximation, the coupled-channels Born approximation, and coupled reaction channels. The adopted spectroscopic amplitudes for the projectile and target overlaps were derived by large-scale shell-model and interacting boson-fermion model calculations. In the calculations the initial state interaction and the nuclear structure model inputs were the same as those adopted in the study of elastic and inelastic scattering and (${}^{18}\mathrm{O},{}^{17}\mathrm{O}$) one-neutron stripping reaction, published elsewhere.

Results: Peaks in the cross section energy spectra corresponding to groups of transitions to ${}^{75}\mathrm{As}$ and ${}^{19}\mathrm{F}$ were identified and the experimental angular distributions were compared with theoretical calculations. A fair agreement between theory and experiment both in cross section values and diffraction pattern is obtained, without the need for any scaling factor, validating the adopted reaction and nuclear structure approaches.

Conclusions: Resembling the case of the (${}^{18}\mathrm{O},{}^{17}\mathrm{O}$) one-neutron stripping reaction, the couplings to the inelastic channels of projectile and target are significant for the one-proton pickup reaction and are likely to also play a role in the single and double charge exchange reactions. The fair description of the data is remarkable since no free parameter was used for this analysis, highlighting that the multichannel approach guarantees an accurate investigation of all the interesting reactions induced by the ${}^{18}\mathrm{O}+{}^{76}\mathrm{Se}$ collision.

The microscopic framework of time-dependent covariant density functional theory is applied to study multinucleon transfer reactions with transfer probabilities calculated using the particle number projection method. It is found that similar total cross sections are obtained with two different relativistic density functionals, PC-PK1 and DD-ME2, as well as with the Skyrme functional SLy5 in a previous study, for multinucleon transfer in the reactions: ${}^{40}\mathrm{Ca}+{}^{124}\mathrm{Sn}$ at $E_{\mathrm{lab}}=170\mathrm{MeV}$, ${}^{40}\mathrm{Ca}+{}^{208}\mathrm{Pb}$ at $E_{\mathrm{lab}}=249\mathrm{MeV}$, and ${}^{58}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ at $E_{\mathrm{lab}}=328.4\mathrm{MeV}$. We report the microscopic calculation of total cross sections for the reactions: ${}^{40}\mathrm{Ar}+{}^{208}\mathrm{Pb}$ at $E_{\mathrm{lab}}=256\mathrm{MeV}$ and ${}^{206}\mathrm{Pb}+{}^{118}\mathrm{Sn}$ at $E_{\mathrm{lab}}=1200\mathrm{MeV}$. Compared to the results obtained with the GRAZING model, the cross sections predicted by the time-dependent covariant density functional theory are in much better agreement with data, and demonstrate the potential of microscopic models based on relativistic density functionals for the description of reaction dynamics.