Above-barrier fusion cross sections for an isotopic chain of oxygen isotopes with $A=16$–19 incident on a ${}^{12}\mathrm{C}$ target are presented. Experimental data are compared with both static and dynamical microscopic calculations. These calculations are unable to explain the $\approx 37\%$ increase in the average above-barrier fusion cross section observed for ${}^{19}\mathrm{O}$ as compared to $\beta$-stable oxygen isotopes. This result suggests that for neutron-rich nuclei existing time-dependent Hartree-Fock calculations underpredict the role of dynamics at near-barrier energies. High-quality measurement of above-barrier fusion for an isotopic chain of increasingly neutron-rich nuclei provides an effective means to probe this fusion dynamics.

The Wildermuth-Tang (WT) prescription is used to verify the Bohr-Sommerfeld (BS) quantization condition in the $\alpha$-decay problem. It gives the global quantum number that relates the number of nodes of the quasibound radial wave function of the $\alpha$-daughter system to the shell model and Pauli exclusion principle. Here we examine the applicability of the WT rule in the $\alpha$-decay microscopic calculations that start with solving the stationary Schrödinger wave equation for different types of the interaction potentials. We found that applying the BS quantization condition along with the WT prescription for the potentials that have no internal pocket yields a large number of nodes in the radial wave function compared to the potentials characterized with an automatic physical internal pocket, which likely produce nodeless or at most a two-node interior wave function. This gives confidence in the latter type of the potentials that efficaciously simulates the Pauli principle by considering the change in the intrinsic kinetic energy. However, it is possible to reproduce the observed half-life data using the potentials that have no automatic internal pocket with applying the BS quantization condition with quantum numbers which are significantly less than that obtained from the WT rule, upon properly normalizing the potential.

Inelastic ${}^6\mathrm{Li}$ scattering at 100 MeV/u on ${}^{12}\mathrm{C}$ and ${}^{93}\mathrm{Nb}$ has been measured with the high-resolution magnetic spectrometer Grand Raiden. The magnetic-rigidity settings of the spectrometer covered excitation energies from 10 to 40 MeV and scattering angles in the range $0^{\circ }<{\theta }_{\text{lab.}}<2^{\circ }$. The isoscalar giant monopole resonance was selectively excited in the present data. Measurements free of instrumental background and the very favorable resonance-to-continuum ratio of ${}^6\mathrm{Li}$ scattering allowed for precise determination of the $E0$ strengths in ${}^{12}\mathrm{C}$ and ${}^{93}\mathrm{Nb}$. It was found that the monopole strength in ${}^{12}\mathrm{C}$ exhausts $52\pm 3^{\text{(stat.)}}\pm 8^{\text{(sys.)}}\%$ of the energy-weighted sum rule (EWSR), which is considerably higher than results from previous $\alpha$-scattering experiments. The monopole strength in ${}^{93}\mathrm{Nb}$ exhausts $92\pm 4^{\text{(stat.)}}\pm {10}^{\text{(sys.)}}\%$ of the EWSR, and it is consistent with measurements of nuclei with mass number of $A\approx 90$. Such comparison indicates that the isoscalar giant monopole resonance distributions in these nuclei are very similar, and no influence due to nuclear structure was observed.

This paper presents numerical cross comparisons and benchmark results for two different kinetic numerical methods, capable of describing relativistic dissipative fluid dynamics in a wide range of kinematic regimes, typical of relevant physics applications, such as transport phenomena in quark-gluon plasmas. We refer to relativistic lattice Boltzmann versus Monte Carlo test-particle methods. Lacking any realistic option for accurate validation vis-á-vis experimental data, we check the consistency of our results against established simulation packages available in the literature. We successfully compare the results of the two aforementioned numerical approaches for momentum integrated quantities like the hydrostatic and dynamical pressure profiles, the collective flow, and the heat flux. These results corroborate the confidence of the robustness and correctness of these computational methods and on the accurate calibration of their numerical parameters with respect to the physical transport coefficients. Our numerical results are made available as Supplemental Material, with the aim of establishing a reference benchmark for other numerical approaches.

Axially deformed relativistic Hartree-Fock (RHF) model with density-dependent meson-nucleon couplings is established in this work, in which the integrodifferential Dirac equations are solved by expanding the Dirac spinor on the spherical Dirac Woods-Saxon base. Using the RHF Lagrangians $\mathrm{PKO}i$ ($i=1,2,3$), the reliability of the method has been illustrated by taking the light ${}^{20}\mathrm{Ne}$, midheavy ${}^{56}\mathrm{Fe}$, and heavy Pb isotopes as examples. As a preliminary application, the systematic study of ${}^{20}\mathrm{Ne}$ shows that PKO1 and PKO3, which contain the $\pi$-pseudovector ($\pi$-PV) coupling, improve the description of the binding energy of ${}^{20}\mathrm{Ne}$, as compared to PKO2 and the selected RMF Lagrangian. Moreover, it is found that the tensor force components carried by the $\pi$-PV coupling can present substantial effects in determining the shape evolution of nucleus.

The dipole strength of the $N=28$ closed-shell nuclide ${}^{54}\mathrm{Fe}$ was studied in photon-scattering experiments using bremsstrahlung produced with electron beams of kinetic energies of 7.5 and 13.9 MeV at the $\gamma \mathrm{ELBE}$ facility as well as using quasimonoenergetic and linearly polarized photon beams of 26 different energies within the range from 5.5 to 11.4 MeV at the $\mathrm{HI}\gamma \mathrm{S}$ facility. About 100 $J=1$ states were newly identified, out of them 19 with $1^{+}$ and 30 with $1^{-}$ assignments. The quasicontinuum of unresolved transitions was included in the analysis of the spectra and the intensities of branching transitions were estimated on the basis of simulations of statistical $\gamma$-ray cascades. As a result, the photoabsorption cross section up to the neutron-separation energy was determined and compared with predictions of the statistical reaction model. The experimental $M1$ strengths from resolved $1^{+}$ states are compared with results of large-scale shell-model calculations.

We have performed a systematic study of the $logft$ values, shape factors, and electron spectra for the second-forbidden nonunique ${\beta }^{-}$ decays of ${}^{24}\mathrm{Na}\left(4^{+}\right)\to {}^{24}\mathrm{Mg}\left(2^{+}\right)$ and ${}^{36}\mathrm{Cl}\left(2^{+}\right){\to }^{36}\mathrm{Ar}\left(0^{+}\right)$ transitions under the framework of the nuclear shell model. We have performed the shell model calculations in the $sd$ model space, using more recent microscopic effective interactions such as Daejeon16, chiral N3LO, and JISP16. These interactions are derived from the no-core shell model wave functions using Okubo-Lee-Suzuki transformation. For comparison, we have also shown the results obtain from the phenomenological USDB interaction. To test the predictive power of these interactions first we have computed low-lying energy spectra of parent and daughter nuclei involved in these transitions. The computed results for energy spectra, nuclear matrix elements, $logft$ values, shape factors, electron spectra, and decomposition of the integrated shape factor are reported and compare with the available experimental data.

$0^{+}, 1^{-}, 2^{+}$, and $3^{-}$ excitations of ${}^{28}\mathrm{Si}$ are investigated via proton and $\alpha$ inelastic scattering off ${}^{28}\mathrm{Si}$. The structure calculation of ${}^{28}\mathrm{Si}$ is performed with the energy variation after total angular momentum and parity projections in the framework of antisymmetrized molecular dynamics (AMD). As a result of the AMD calculation, the oblate ground and prolate bands, $0^{+}$ and $3^{-}$ excitations, and the $1^{-}$ and $3^{-}$ states of the $K^{\pi }=0^{-}$ band are obtained. Using the matter and transition densities of ${}^{28}\mathrm{Si}$ obtained by AMD, microscopic coupled-channels calculations of proton and $\alpha$ scattering off ${}^{28}\mathrm{Si}$ are performed. The proton-${}^{28}\mathrm{Si}$ potentials in the reaction calculation are microscopically derived by folding the Melbourne $g$-matrix $NN$ interaction with the AMD densities of ${}^{28}\mathrm{Si}$. The $\alpha -{}^{28}\mathrm{Si}$ potentials are obtained by folding the nucleon-${}^{28}\mathrm{Si}$ potentials with an $\alpha$ density. The calculation reasonably reproduces the observed elastic and inelastic cross sections of proton and $\alpha$ scattering. Transition properties are discussed by combining the reaction analysis of proton and $\alpha$ scattering and structure features such as transition strengths and form factors. The isoscalar monopole and dipole transitions are focused.

Background: Fast-neutron-induced reactions can be used to characterize reaction mechanisms, investigate nuclear structure, and impose constraints on nuclear models. Because of the difficulty in predicting such effects, experimental data are important to constrain models. Thallium isotopes located close to the doubly magic ${}^{208}\mathrm{Pb}$ nucleus are important for comparison with shell-model calculations.

Purpose: Study the population of excited states in ${}^{203}\mathrm{Tl}$ and lighter isotopes in such reactions.

Methods: $\gamma$-ray cross sections were measured. The data were taken by using the Germanium Array for Neutron-Induced Excitations spectrometer. The pulsed neutron source of the Los Alamos Neutron Science Center's Weapons Neutron Research facility provided neutrons in the energy range from 1 to 300 MeV. The time-of-flight technique was used to determine the incident neutron energies.

Results: Cross sections for emission of several $\gamma$ rays in 20 reaction channels were determined. Candidates for the intruder $9/2^{-}$ state in ${}^{203}\mathrm{Tl}$, from the odd proton in the $h_{9/2}$ orbital, and the first $5^{+}$ states in ${}^{202,204}\mathrm{Tl}$, from admixture of configurations, were identified.

Conclusions:The excitation energy of the candidate $9/2^{-}, \pi h_{9/2}$ state is in good agreement with the theoretical prediction from a semi-empirical weak-coupling model and its half-life is in the range of tens of nanoseconds. The feeding of a previously known isomer in ${}^{202}\mathrm{Tl}$ exhibits similarities with the feeding of other isomers in this mass region.

The multiplicity percentile dependence of cumulants, of net-proton number distributions in Au-Au collisions at $\sqrt{s_{NN}}=200$ GeV and Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV, has been investigated using the Angantyr model (the heavy-ion extension of the pythia 8 model). The effects of finite transverse momentum ($p_T$) and pseudorapidity ($\eta$) acceptance on the net-proton cumulants have also been studied. Furthermore, the effects of the hydrodynamic expansion and feed down from weak decays were explored. It was found that radial flow has substantial impact on the cumulants and their ratios, while weak decays have a finite but relatively smaller effect. The obtained values of cumulants and their ratios with the Angantyr model, where the formation of thermalized medium is not assumed, can serve as a baseline for future measurements.

Nucleon effective masses are studied in the framework of the Brueckner-Hartree-Fock many-body approach at finite temperature. Self-consistent calculations using the Argonne $V_{18}$ interaction including a microscopic three-body force are reported for varying temperature and proton fraction up to several times the nuclear saturation density. Our calculations are based on the exact treatment of the center-of-mass momentum instead of the average-momentum approximation employed in previous works. We discuss in detail the effects of the temperature together with those of the three-body force, the density, and the isospin asymmetry. We also provide an analytical fit of the effective mass taking these dependencies into account. The temperature effects on the cooling of neutron stars are briefly discussed based on the results for $\beta$-stable matter.

Background: Path integrals are a powerful tool for solving problems in quantum theory that are not amenable to a treatment by perturbation theory. Most path integral computations require an analytic continuation to imaginary time. While imaginary time treatments of scattering are possible, imaginary time is not a natural framework for treating scattering problems. More importantly, quantum algorithms for calculating path integrals require real-time evolution.

Purpose: We test a recently introduced method for performing direct calculations of scattering observables using real-time path integrals in order to understand the challenges facing real-time path integral calculations of scattering observables.

Method: The computations are based on a new interpretation of the path integral as the expectation value of a potential functional on cylinder sets of continuous paths with respect to a complex probability distribution. The method can in principle be applied to arbitrary short-range potentials.

Results: The method is applied to compute matrix elements of Møller wave operators applied to narrow wave packets. These are used to calculate half-shell sharp-momentum transition matrix elements for one-dimensional potential scattering. The calculations for half-shell transition operator matrix elements converge to the numerical solution of the Lippmann-Schwinger equation.

Conclusions: This work presents a proof in principle that scattering observables can be computed using real-time Feynman path integrals. While the computational method is not efficient, it can be improved. It provides a laboratory for studying quantum computational algorithms that are applicable to scattering problems.

The quadrupole collective Hamiltonian, based on relativistic energy density functionals, is extended to include a pairing collective coordinate. In addition to quadrupole shape vibrations and rotations, the model describes pairing vibrations and the coupling between shape and pairing degrees of freedom. The parameters of the collective Hamiltonian are determined by constrained self-consistent relativistic mean-field plus Bardeen-Cooper-Schrieffer ($\mathrm{RMF}+\mathrm{BCS}$) calculations in the space of intrinsic shape and pairing deformations. The effect of coupling between shape and pairing degrees of freedom is analyzed in a study of low-energy spectra and transition rates of four axially symmetric $N=92$ rare-earth isotones. When compared to results obtained with the standard quadrupole collective Hamiltonian, the inclusion of dynamical pairing increases the moment of inertia, lowers the energies of excited $0^{+}$ states, and reduces the $E0$ transition strengths, in better agreement with data.

The dependence of the nuclear temperature on the source neutron-proton ($N/Z$) asymmetry has been experimentally investigated with the light charged particles (LCPs) generated from 13 reaction systems with different $N/Z$ asymmetries, ${}^{64}\mathrm{Zn}$ on ${}^{112}\mathrm{Sn}$, and ${}^{70}\mathrm{Zn}$, ${}^{64}\mathrm{Ni}$ on ${}^{112,124}\mathrm{Sn}$, ${}^{58,64}\mathrm{Ni}$, ${}^{197}\mathrm{Au}$, and ${}^{232}\mathrm{Th}$ at 40 MeV/u. A rather weak $N/Z$ asymmetry dependence of the source temperature has been qualitatively inferred from the extracted $N/Z$ asymmetry dependence of the apparent temperature and that of the relative temperature change by the sequential decay effects with the help of the theoretical simulations. Comparing the present result with those from our previous work and other available experimental results, a weak $N/Z$ asymmetry dependence of nuclear temperature is commonly observed in different independent experiments and with different thermometers, except for the result reported by McIntosh et al. [Phys. Lett. B 719, 337 (2013)]. The origin of the difference between the conclusion of the former group and that of McIntosh et al. is addressed, using statistical multifragmentation model (SMM) simulations.

Using the improved scission-point model, the mass and charge distributions of fission fragments of the compound nuclei ${}^{180,182,190,198}\mathrm{Hg}^{*}$ and ${}^{202}\mathrm{Pb}^{*}$ formed in complete fusion reactions ${}^{36}\mathrm{Ar}+{}^{144}\mathrm{Sm}$, ${}^{40}\mathrm{Ca}+{}^{142}\mathrm{Nd}$, ${}^{36}\mathrm{Ar}+{}^{154}\mathrm{Sm}$, $\alpha +{}^{194}\mathrm{Pt}$, and ${}^{48}\mathrm{Ca}+{}^{154}\mathrm{Sm}$ are studied and compared with available experimental data. The transition is explained from the mass-asymmetric distribution in fissioning ${}^{180,182,190}\mathrm{Hg}^{*}$ to the mass-symmetric distribution found in fissioning ${}^{198}\mathrm{Hg}^{*}$ and ${}^{202}\mathrm{Pb}^{*}$. The retention of the asymmetric mass distributions is treated in the case of fissioning ${}^{180,182,190}\mathrm{Hg}^{*}$ with increasing excitation energy. In the fissioning ${}^{198}\mathrm{Hg}^{*}$ and ${}^{182}\mathrm{Hg}^{*}$, completely different shapes are predicted for charge and mass yields.

Collective mass tensors derived in the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) method are employed in a study of induced fission dynamics. Together with a collective potential determined in deformation-constrained self-consistent mean-field calculations based on nuclear energy density functionals, the mass tensors specify the collective Hamiltonian that governs the time evolution of the nuclear wave function from an initial state at equilibrium deformation, up to scission and the formation of fission fragments. In an illustrative calculation of low-energy induced fission of ${}^{228}\mathrm{Th}$, ${}^{230}\mathrm{Th}$, ${}^{234}\mathrm{U}$, and ${}^{240}\mathrm{Pu}$, we compare the nonperturbative and perturbative cranking ATDHFB mass tensors in the plane of axially symmetric quadrupole and octupole deformations, as well as the resulting charge yields.

The quark gluon plasma produced in ultrarelativistic heavy-ion collisions at the Large Hadron Collider (LHC) can be studied by measuring the modifications of jets formed by hard scattered partons which interact with the medium. We studied these modifications via angular correlations of jets with charged hadrons for jets with momenta $20<p_{\mathrm{T}}^{\mathrm{jet}}<40$ GeV/$c$ as a function of the associated particle momentum. The reaction plane fit method is used in this analysis to remove the flow modulated background. The analysis of angular correlations for different orientations of the jet relative to the second order event plane allows for the study of the path length dependence of medium modifications to jets. We present the dependence of azimuthal angular correlations of charged hadrons with respect to the angle of the axis of a reconstructed jet relative to the event plane in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. The dependence of particle yields associated with jets on the angle of the jet with respect to the event plane is presented. Correlations at different angles relative to the event plane are compared through ratios and differences of the yield. No dependence of the results on the angle of the jet with respect to the event plane is observed within uncertainties, which is consistent with no significant path length dependence of the medium modifications for this observable.

The correlation between the harmonic flow and the transverse momentum in relativistic heavy ion collisions is calculated in the hydrodynamic model. The partial correlation coefficient, corrected for fluctuations of multiplicity, is compared to experimental data. Estimators of the final transverse momentum and harmonic flow are used to predict the value of the correlation coefficient from the moments of the initial distribution. A good description of the hydrodynamic simulation results is obtained if the estimator for the final transverse momentum, besides the transverse size and the entropy, includes also the eccentricities.

An effective Fourier nuclear shape parametrization, which describes well the most relevant degrees of freedom on the way to fission is used to construct a three-dimensional collective model. The potential energy surface is evaluated within the macroscopic-microscopic approach based on the Lublin-Strasbourg drop macroscopic energy and Yukawa-folded single-particle potential. A phenomenological inertia parameter is used to describe the kinetic properties of the fissioning system. The fission fragment mass yields are obtained by using an approximate solution of the underlying Hamiltonian. The predicted mass fragmentations for even-even Pt to Ra isotopes are compared with available experimental data. Their main characteristics are well reproduced when the neck rupture probability dependent on the neck radius is introduced.