We provide a microscopic description of the fusion reactions between ${}^{40,48}\mathrm{Ca}$ and ${}^{78}\mathrm{Ni}$. The internuclear potentials are obtained using the density-constrained (DC) time-dependent Hartree-Fock (TDHF) approach and fusion cross sections are calculated via the incoming wave boundary condition method. By performing DC-TDHF calculations at several selected incident energies, the internuclear potentials for both systems are obtained and the energy-dependence of fusion barrier are revealed. The influence of tensor force on internuclear potentials of ${}^{48}\mathrm{Ca}+{}^{78}\mathrm{Ni}$ is more obvious than those of ${}^{40}\mathrm{Ca}+{}^{78}\mathrm{Ni}$. By comparing the calculated fusion cross sections between ${}^{40}\mathrm{Ca}+{}^{78}\mathrm{Ni}$ and ${}^{48}\mathrm{Ca}+{}^{78}\mathrm{Ni}$, an interesting enhancement of subbarrier fusion cross sections for the former system is found, which can be explained by the narrow width of internuclear potential for ${}^{40}\mathrm{Ca}+{}^{78}\mathrm{Ni}$ while the barrier heights and positions are very close to each other. The tensor force suppresses the subbarrier fusion cross sections of both two systems.

The evaporation cross sections in fusion reactions by ${}^{40}\mathrm{Ar}$ bombarding deformed nuclei were compared to calculations using a modified Woods-Saxon potential model together with the standard statistical model. The results show that the predictions overestimate the experimental yields of these reaction products up to two orders of magnitude as the charge number of compound nuclei ($Z_{CN}\ge 85$) increases, and suggest that the fusion process strongly depends on the orientation of the deformed target according to density-constrained time-dependent Hartree-Fock calculations.

Excited levels of ${}^{130}\mathrm{Te}$ were studied with the $(n,$ $n^{\prime }\gamma )$ reaction. Excitation functions, $\gamma \gamma$ coincidences, angular distributions, and Doppler shifts were measured for $\gamma$ rays from levels up to an excitation energy of 3.3 MeV. Detailed information that includes level lifetimes, multipole-mixing ratios, branching ratios, and electromagnetic transition rates deduced from these measurements is presented. Large-scale shell model calculations performed with all proton and neutron orbitals in the 50–82 shell are compared to these data, with generally good agreement, particularly for the positive-parity states. To investigate emerging collectivity in ${}^{130}\mathrm{Te}$, the Kumar-Cline sum rules were used to evaluate rotational invariants from the shell model calculations. Whereas the ground state and first-excited state show the greatest average deformation, as expected, all of the low-lying states are weakly deformed and triaxial.

Two-nucleon momentum correlation functions are investigated for different single thermal sources at given initial temperature $\left(T\right)$ and density $\left(\rho \right)$. To this end, the space-time evolutions of various single excited nuclei at $T=1–20\mathrm{MeV}$ and $\rho =0.2-1.2 {\rho }_0$ are simulated by using the thermal isospin-dependent quantum molecular dynamics model. Momentum correlation functions of identical proton-pairs [$C_{pp}\left(q\right)$] or neutron-pairs [$C_{nn}\left(q\right)$] at small relative momenta are calculated by Lednický and Lyuboshitz analytical method. The results illustrate that $C_{pp}\left(q\right)$ and $C_{nn}\left(q\right)$ are sensitive to the source size ($A$) at lower $T$ or higher $\rho$, but almost not at higher $T$ or lower $\rho$. And the sensitivities become stronger for smaller source. Moreover, the $T, \rho$, and $A$ dependencies of the Gaussian source radii are also extracted by fitting the two-proton momentum correlation functions, and the results are consistent with the above conclusions.

Equation of state with quantum statistics corrections is derived for systems of the Fermi and Bose particles by using their van der Waals (vdW) and effective density-dependent Skyrme mean-field interactions. The first few orders of these corrections over a small quantum-statistics parameter, $\varepsilon \approx {\hslash }^{3}n{\left(mT\right)}^{-3/2}{g}^{-1}$, where $n$ and $T$ are the particle number density and temperature, $m$ and $g$ are the mass and degeneracy factor of particles, are analytically obtained. For an interacting system of nucleon and $\alpha$ particles, a small impurity of $\alpha$ particles to a nucleon system at leading first order in both $\alpha$- particle and nucleon small parameters $\varepsilon$ does not change the basic results for the symmetric nuclear matter in the quantum vdW consideration much. Our approximate analytical results for the quantum vdW and Skyrme mean-field approaches are in a good agreement with accurate numerical calculations.

Correlation measurements with respect to the spectator and participant planes in relativistic heavy ion collisions were proposed to extract the chiral magnetic effect (CME) from background dominated azimuthal correlators. This paper investigates the effects of two- and three-particle nonflow correlations on the extracted CME signal fraction, $f_{\text{CME}}$. It is found, guided by a multiphase transport (ampt) model and the heavy ion jet interaction generator (hijing) together with experimental data, that the nonflow effects amount to approximately $(4\pm 5)\%$ and $(-5\pm 3)\%$ without and with pseudorapidity gaps, respectively, in 20–50% centrality Au$+$Au collisions at $\sqrt{s_{NN}}=200\text{GeV}$.

The paper gives physical justification of a new method for measuring the degree of linear photon-beam polarization, which relies on the experimental data for the total cross section of spin $S$ = 1 transitions in the ${}^4\mathrm{He}(\gamma ,p){}^3\mathrm{H}$ and ${}^4\mathrm{He}(\gamma ,n){}^3\mathrm{He}$ reactions. The experimental information on the cross section was obtained from both the mentioned reactions and the reactions of radiative capture of protons by tritium nuclei. The total cross section for transitions with spin $S$ = 1 is $\approx 1\%$ of the total cross section for the reaction. The ratio of the differential cross section in the collinear geometry, specified by the $S$ = 1 transitions, to the differential reaction cross section at the nucleon emission angle ${\theta }_N={90}^{\circ }$ in the energy range 20 $\le E_{\gamma }\le$ 100 MeV is independent of the photon energy within the experimental error. The total cross section for the $S$ = 1 transitions can be also determined from the experimental data on the cross-section asymmetry of the reaction with linearly polarized photons $\mathrm{\Sigma }\left({\theta }_N\right)$. However, the total cross section for transitions with spin $S$ = 1, calculated from the asymmetry of the cross section $\mathrm{\Sigma }\left({\theta }_N\right)$, is several times greater than that calculated from the differential cross section. This inconsistency of the experimental data may be due, in particular, to the overestimate of the degree of linear photon-beam polarization. The above-mentioned reactions seem to be more convenient for measuring the degree of linear photon-beam polarization than the deuteron photodisintegration reactions.

The uncoupled $P$-wave channels of nucleon-nucleon scattering are studied in an effective field theory (EFT) including a perturbative dibaryon field and perturbative pions. Good agreement between EFT results and the Nijmegen partial wave analysis is observed up to a center-of-mass momentum $k\approx 400$ MeV. Using a method that combines renormalization and fitting together, the long-standing convergence problem of EFTs in these channels with perturbative pions, for momenta above the pion mass is addressed from a new perspective.

The availability of a comparatively complete data set for the elastic and inelastic scattering of a 45-MeV beam of ${}^{11}\mathrm{B}$ ions from a ${}^{14}\mathrm{C}$ target, together with an angular distribution for the ${}^{14}\mathrm{C}({}^{11}\mathrm{B},{}^{12}\mathrm{C}){}^{13}\mathrm{B}$ proton pickup reaction enables a determination of the $\langle {}^{14}\mathrm{C}\mid {}^{13}\mathrm{B}+p\rangle$ asymptotic normalization coefficient (ANC) using the coupled reaction channel (CRC) technique. The complete nature of the data set allows two-step contributions to the reaction mechanism to be controlled while a set of $\langle {}^{12}\mathrm{C}\mid {}^{11}\mathrm{B}+p\rangle$ overlaps obtained from a consistent analysis of ($d,{}^3\mathrm{He}$) and ($e,e^{\prime }p$) data fixes the projectile overlaps. We find that the level of completeness of the modeling of the reaction mechanism has a significant effect on the value obtained for the ANC, with a distorted wave Born approximation analysis yielding a significantly larger ANC than the full CRC calculation. The final result obtained, when compared with the theoretical value calculated within the source term approach, is in accord with trends for proton removal from similar $p$-shell nuclei.

Background: Charge-exchange (CE) reactions offer a major opportunity to excite nuclear isovector modes, providing important clues about the nuclear interaction in the medium. Moreover, double charge-exchange reactions are proving to be a tempting tool to access nuclear transition matrix elements (NMEs) related to double beta-decay processes. The latter are also of crucial importance to extract neutrino properties from the half-life of the hypothetical neutrinoless double beta decay and to search for physics beyond the standard model.

Purpose: Through a multichannel experimental analysis and a consistent theoretical approach of the ${}^{116}\mathrm{Cd}({}^{20}\mathrm{Ne},{}^{20}\mathrm{F}){}^{116}\mathrm{In}$ single charge-exchange (SCE) reaction at 306 MeV, we aim at disentangling from the experimental cross section the contribution of the competing mechanisms associated with second- or higher-order sequential transfer and/or inelastic processes.

Methods: We measured excitation energy spectra and absolute cross sections for elastic $+$ inelastic, one-proton transfer and SCE channels by using the MAGNEX large acceptance magnetic spectrometer to detect the ejectiles. For the first two channels, we also extracted the experimental cross-section angular distributions. The experimental data are compared with theoretical predictions obtained by performing two-step distorted-wave Born approximation and coupled reaction channel calculations. We employ spectroscopic amplitudes for single-particle transitions derived within a large-scale shell-model approach and different optical potentials for modeling the initial- and the final-state interactions.

Results: The present study significantly mitigates the possible model dependence existing in the description of these complex reaction mechanisms thanks to the satisfactory reproduction of several channels at once. In particular, our work demonstrates that the two-step transfer mechanisms produce a non-negligible contribution to the total cross section of the ${}^{116}\mathrm{Cd}({}^{20}\mathrm{Ne},{}^{20}\mathrm{F}){}^{116}\mathrm{In}$ reaction channel, although a relevant fraction is still missing, being ascribable to the direct SCE mechanism, which is not addressed here.

Conclusions: Our analysis provides a careful estimation of the sequential transfer processes which are competing with the direct SCE mechanism for the heavy ion reaction under investigation. The study suggests that the direct SCE should play an important role among the mechanisms populating the final channel. Nevertheless, the analysis of the higher-order processes considered here is mandatory to isolate the direct SCE process contribution and approach structure information on the corresponding NME from the reaction cross section. The description of the latter process and the competition between the two mechanisms deserves further investigation.

Background: The stability of the transfermium nucleus against fission is mainly determined by the shell correction depending on its angular momentum and excitation energy.

Purpose: The study of the fast fission process of the transfermium nucleus ${}^{248}\mathrm{No}$ and its dependence on the interaction energy and introduced angular momentum.

Methods: Mass-energy distributions of the ${}^{248}\mathrm{No}$ fission fragments formed in the ${}^{40}\mathrm{Ca}$ + ${}^{208}\mathrm{Pb}$ reaction at energies above the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET at the ${}^{40}\mathrm{Ca}$-beam energies of 223, 250, and 284 MeV.

Results: The contribution of the fast fission process is determined from the calculations of the driving potential, taking into account shell effects and rotational energy and amounts to 39% and 61% at 250 and 284 MeV, respectively. The mass-energy distributions of the quasifission and fast fission fragments have been extracted by subtracting the mass-energy matrices associated with compound nucleus fission from those of all measured fissionlike events. The asymmetric fragments with masses 97 and 151 u were found to be the most probable in the fast fission of ${}^{248}\mathrm{No}$. With increasing ${}^{40}\mathrm{Ca}$ energy from 250 to 284 MeV the mass distributions of the fast fission fragments change slightly.

Conclusions: Contrary to quasifission in which the fragments are focused mainly around the closed neutron or proton shells, the influence of known proton or neutron shells on the asymmetric mass distribution in the fast fission process was not observed.

Background: The photon strength functions (PSFs) and nuclear level density (NLD) are key ingredients for calculation of the photon interaction with nuclei, in particular the reaction cross sections. These cross sections are important especially in nuclear astrophysics and in the development of advanced nuclear technologies.

Purpose: The role of the scissors mode in the $M1$ PSF of (well-deformed) actinides was investigated by several experimental techniques. The analyses of different experiments result in significant differences, especially on the strength of the mode. The shape of the low-energy tail of the giant electric dipole resonance is uncertain as well. In particular, some works proposed a presence of the $E1$ pygmy resonance just above 7 MeV. Because of these inconsistencies additional information on PSFs in this region is of great interest.

Methods: The $\gamma$-ray spectra from neutron-capture reactions on the ${}^{234}\mathrm{U}$, ${}^{236}\mathrm{U}$, and ${}^{238}\mathrm{U}$ nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated $s$-wave resonances up to about 140 eV.

Results: The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions and nuclear level density. No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) $E1$ PSF, which match the experimental spectra as well as the total radiative widths.

Conclusions: The constant temperature energy dependence is favored for a NLD. The tail of giant electric dipole resonance is well described by the MGLO model of the $E1$ PSF with no hint of pygmy resonance. The $M1$ PSF must contain a very strong, relatively wide, and likely double-resonance scissors mode. The mode is responsible for about a half of the total radiative width of neutron resonances and significantly affects the radiative cross section.

We reconcile for the first time the strict mathematical formalism of multivariate cumulants with the use of cumulants in anisotropic flow analyses in high-energy nuclear collisions. This reconciliation yields to the next generation of estimators to be used in flow analyses. We review all fundamental properties of multivariate cumulants and use them as a foundation to establish two simple necessary conditions to determine whether some multivariate random variable is a multivariate cumulant in the basis they are expressed in. We argue that properties of cumulants are preserved only for the stochastic variables on which the cumulant expansion has been performed directly, and if there are no underlying symmetries due to which some terms in the cumulant expansion are identically zero. We illustrate one possibility of new multivariate cumulants of azimuthal angles by defining them event-by-event and by keeping all nonisotropic terms in the cumulant expansion. Furthermore, we introduce new cumulants of flow amplitudes named asymmetric cumulants, which generalize recently introduced symmetric cumulants for the case when flow amplitudes are raised to different powers. Finally, we present the new concept of cumulants of symmetry plane correlations and provide the first realization for the lowest orders. The new estimators can be used directly to constrain the multivariate probability density function of flow fluctuations, since its functional form can be reconstructed only from its true moments or cumulants. The new definition for cumulants of azimuthal angles enables separation of nonflow and flow contributions and offers first insights into how the combinatorial background contributes for small multiplicities to flow measurements with correlation techniques. All the presented results are supported by Monte Carlo studies using state-of-the-art models.

Background: Stellar nucleosynthesis of elements heavier than iron is driven by neutron capture processes. ${}^{92}\mathrm{Zr}$ is positioned at a strategic point along the slow nucleosynthesis path, given its proximity to the neutron magic number $N=50$ and its position at the matching region between the weak and main slow processes.

Purpose: In parallel with recent improved astronomical data, the extraction of accurate Maxwellian averaged cross sections (MACSs) derived from a more complete and accurate set of resonance parameters should allow for a better understanding of the stellar conditions at which nucleosynthesis takes place.

Methods: Transmission and capture cross section measurements using enriched ${}^{92}\mathrm{Zr}$ metallic samples were performed at the time-of flight facilities GELINA of JRC-Geel (BE) and n_TOF of CERN (CH). The neutron beam passing through the samples was investigated in transmission measurements at GELINA using a Li-glass scintillator. The $\gamma$ rays emitted during the neutron capture reactions were detected by ${\mathrm{C}}_6{\mathrm{D}}_6$ detectors at both GELINA and n_TOF.

Results: Resonance parameters of individual resonances up to 81 keV were extracted from a combined resonance shape analysis of experimental transmissions and capture yields. For the majority of the resonances the parity was determined from an analysis of the transmission data obtained with different sample thicknesses. Average resonance parameters were calculated.

Conclusions: Maxwellian averaged cross sections were extracted from resonances observed up to 81 keV. The MACS for $kT=30\mathrm{keV}$ is fully consistent with experimental data reported in the literature. The MACSs for $kT\lesssim 15\mathrm{keV}$ are in good agreement with those derived from the ENDF/B-VIII.0 library and recommended in the KADoNiS database. For $kT$ higher than 30 keV differences are observed. A comparison with MACSs obtained with the cross sections recommended in the JEFF-3.3 and JENDL-4.0 libraries shows discrepancies even for $kT\lesssim 15\mathrm{keV}$.

The study of inhomogeneous neutron matter can provide insights into the structure of neutron stars as well as their dynamics in neutron-star mergers. In this work we tackle pure neutron matter in the presence of a periodic external field by considering a finite (but potentially large) number of particles placed in periodic boundary conditions. We start with the simpler setting of a noninteracting gas and then switch to a Skyrme-Hartree-Fock approach, showing static-response results for five distinct Skyrme parametrizations. We explain both the technical details of our computational approach, as well as the significance of these results as a general finite-size extrapolation scheme that may be used by ab initio practitioners to approach the static-response problem of neutron matter in the thermodynamic limit.

The density-dependent cluster model (DDCM) is one of the successful theoretical models for $\alpha$-decay studies. It gives a good description of the experimental $\alpha$-decay half-lives for a wide range of $\alpha$ emitters. Nuclear surface diffuseness, one important quantity in determining the nucleon density profiles, is extremely sensitive to deformation, Bohr, Mottelson et al. proposed an anisotropic feature of the surface diffuseness for the deformed nuclei. In this work, an improved version of the density-dependent cluster model, abbreviated as $\mathrm{DDCM}+$, is developed to optimize $\alpha$-decay calculations on half-lives, by accounting for the anisotropy and polarization effects of surface diffuseness due to nuclear deformation. Within a deformation-dependent diffuseness correction, the response of $\alpha$-decay dynamics to the diffuseness anisotropy is first investigated in detail. It demonstrates that such an anisotropic deformation-dependent diffuseness would change the shape of nucleon density profile and effective $\alpha$-core interactions, yielding longer calculated $\alpha$-decay half-lives, as well as suggesting larger estimated $\alpha$-preformation factors. The systematic calculations on $\alpha$-decay half-lives are subsequently performed for 157 even-even nuclei with $52\le Z\le 118$, which reproduce the experimental data within an average factor of 1.88, and drastically reduce the root-mean-square deviations between theoretical results and experimental data by about $41.4\%$ in contrast to conventional DDCM. Noticeably, the theoretical result of new isotope ${}^{214}\mathrm{U}$ [Zhang et al., Phys. Rev. Lett. 126, 152502 (2021)] given by $\mathrm{DDCM}+$ also shows good agreement with the latest reported experimental data, demonstrating the high reliability of the improved model. It is expected that this improved model could be useful for future experimental and theoretical studies of $\alpha$ decays.

Using and comparing kinetic theory and second-order Chapman-Enskog hydrodynamics, we study the nonconformal dynamics of a system undergoing Bjorken expansion. We use the concept of “free-streaming fixed lines” for scaled shear and bulk stresses in nonconformal kinetic theory and hydrodynamics, and show that these fixed lines behave as early-time attractors and repellors of the evolution. In the conformal limit, the free-streaming fixed lines reduce to the well-known fixed points of conformal Bjorken dynamics. A new fixed point in the free streaming regime is identified which lies at the intersection of these fixed lines. Contrary to the conformal scenario, both kinetic theory and hydrodynamics predict the absence of attractor behavior in the normalized shear stress channel. In kinetic theory a far-off-equilibrium attractor is found for the normalized effective longitudinal pressure, driven by rapid longitudinal expansion. Second-order viscous hydrodynamics fails to accurately describe this attractor. From a thorough analysis of the free-streaming dynamics in Chapman-Enskog hydrodynamics we conclude that this failure results from an inaccurate approximation of the fixed lines and a related incorrect description of the nature of the fixed point. A modified anisotropic hydrodynamic description is presented that provides excellent agreement with kinetic theory results and reproduces the far-from-equilibrium attractor for the scaled longitudinal pressure.

We study neutrino-nucleus charged-current reactions on finite nuclei for the situation in which an outgoing muon and a proton are detected in coincidence; i.e., we focus on semi-inclusive cross sections. We limit our attention to one-body current interactions (quasielastic scattering) and assess the impact of different nuclear effects in the determination of the neutrino energy. We identify the regions in phase space where the neutrino energy can be reconstructed relatively well and study whether the cross section in those regions is significant. Our results indicate that it is possible to filter more than 50% of all events according to the muon and proton kinematics, so that for the DUNE and T2K fluxes the neutrino energy can be determined with uncertainties of less than 1% and 3%, respectively. Furthermore, we find that the reconstructed neutrino energy does not depend strongly on how one treats the final-state interactions and is not much affected by the description of the initial state. On the other hand, the estimations of the uncertainty on the neutrino energy show important sensitivity to the modeling of the initial state.

In this paper we study the correlation between the evolution of nuclear collective motion and neutron-proton interactions. We construct empirical neutron-proton interactions (denoted by $V_{\mathrm{NP}}$) for nuclei in the $(28<Z<50,$ $50<N<82)$, $(50<Z<82,$ $50<N<82$), and $(50<Z<82,$ $82<N<126)$ major shells. The ratios between $V_{\mathrm{NP}}$ and $N_{\mathrm{n}}{N}_{\mathrm{p}}$ (the product of valence proton number and valence neutron number) are found to be different for particle-particle, particle-hole, and hole-hole regions of the same major shell, suggesting different average strengths of neutron-proton interactions for these regions. Very interestingly, collective observables of even-even nuclei, e.g., $2^{+}$ and $4^{+}$ state energies, which follow different trajectories in the $N_{\mathrm{n}}{N}_{\mathrm{p}}$ scheme for particle-particle, particle-hole, and hole-hole regions, are found to form one unified and compact trajectory if those collective observables are plotted in terms of total neutron-proton interactions, $V_{\mathrm{NP}}$.