In this work, we expand upon our previous study of the effect of surface vibrations (low-lying vibrational states) on the calculation of penetration probability in $\alpha$ decay of spherical isotopes [Phys. Rev. C 91, 034611 (2015)]. For this pupose, the Coulomb and proximity potential model, taking into account the ground state deformations of the involved nuclei along with the surface vibrations in the daughter nucleus, is used to evaluate the $\alpha$ decay probability. The results are compared with those obtained with a spherical potential barrier, which shows the dramatic effect of employing the ground state deformations in case of deformed nuclei. As well, inclusion of surface vibrations gives rise to an increase in the value of tunneling probability in better agreement with experimental data.

We make predictions for the cross sections of coherent photoproduction of $\rho ,\varphi ,J/\psi ,\psi \left(2S\right)$, and $\mathrm{{\rm Y}}\left(1S\right)$ mesons in Pb-Pb ultraperipheral collisions (UPCs) at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ in the kinematics of run 2 at the Large Hadron Collider extending the approaches successfully describing the available Pb-Pb UPC data at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$. Our results illustrate the important roles of hadronic fluctuations of the photon and inelastic nuclear shadowing in photoproduction of light vector mesons on nuclei and the large leading twist nuclear gluon shadowing in photoproduction of quarkonia on nuclei. We show that the ratio of $\psi \left(2S\right)$ and $J/\psi$ photoproduction cross sections in Pb-Pb UPCs is largely determined by the ratio of these cross sections on the proton. We also argue that UPCs with electromagnetic excitations of the colliding ions followed by the forward neutron emission allows one to significantly increase the range of photon energies accessed in vector meson photoproduction on nuclei.

The neutron capture cross sections of light nuclei ($A<56$) are important for $s$-process scenarios since they act as neutron poisons. We report on measurements of the neutron capture cross sections of ${}^{41}\mathrm{K}$ and ${}^{45}\mathrm{Sc}$, which were performed at the Karlsruhe 3.7 MV Van de Graaff accelerator via the activation method in a quasistellar neutron spectrum corresponding to a thermal energy of $kT=25$ keV. Systematic effects were controlled by repeated irradiations, resulting in overall uncertainties of less than 3%. The measured spectrum-averaged data have been used to normalize the energy-dependent $(n,\gamma )$ cross sections from the main data libraries JEFF-3.2, JENDL-4.0, and ENDF/B-VII.1, and a set of Maxwellian averaged cross sections was calculated for improving the $s$-process nucleosynthesis yields in AGB stars and in massive stars. At $kT=30$ keV, the new Maxwellian averaged cross sections of ${}^{41}\mathrm{K}$ and ${}^{45}\mathrm{Sc}$ are $19.2\pm 0.6$ mb and $61.3\pm 1.8$ mb, respectively. Both values are 20% lower than previously recommended. The effect of neutron poisons is discussed for nuclei with $A<56$ in general and for the investigated isotopes in particular.

We have studied the effects of tensor coupling of $\omega$ and $\rho$ meson terms, the Coulomb exchange term in local density approximation, and various isoscalar-isovector coupling terms of relativistic mean-field model on the properties of nuclear matter, finite nuclei, and superheavy nuclei. We found that for the same fixed value of symmetry energy $J$ or its slope $L$ the presence of tensor coupling of $\omega$ and $\rho$ meson terms and the Coulomb exchange term yields thicker neutron skin thickness of ${}^{208}\mathrm{Pb}$. We also found that the roles of tensor coupling of $\omega$ and $\rho$ meson terms, the Coulomb-exchange term in local density approximation, and various isoscalar-isovector coupling terms on the bulk properties of finite nuclei vary depending on the corresponding nucleus mass. However, on average, tensor coupling terms play a significant role in predicting the bulk properties of finite nuclei in a quite wide mass range, especially in binding energies. We also observed that for some particular nuclei, the corresponding experimental data of binding energies are rather less compatible with the presence of the Coulomb-exchange term in local density approximation and they tend to disfavor the presence of isoscalar-isovector coupling term with too-high $\mathrm{\Lambda }$ value. Furthermore, we have found that these terms influence the detail properties of ${}^{292}120$ superheavy nucleus such as binding energies, the magnitude of two-nucleon gaps, single-particle spectra, neutron densities, neutron skin thicknesses, and mean-square charge radii. However, the shell-closure predictions of ${}^{208}\mathrm{Pb}$ and ${}^{292}120$ nuclei are not affected by the presence of these terms.

The preformation probabilities of an $\alpha$ cluster inside radioactive parent nuclei for both odd-even and odd-odd nuclei are investigated. The calculations cover the isotopic chains from Ir to Ac in the mass regions $166\le A\le 215$ and $77\le Z\le 89$. The calculations are employed in the framework of the density-dependent cluster model. A realistic density-dependent nucleon-nucleon $\left(NN\right)$ interaction with a finite-range exchange part is used to calculate the microscopic $\alpha$-nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the $\alpha$ and daughter nuclei has been included in the folding model through the finite-range exchange part of the $NN$ interaction. The calculated potential is then implemented to find both the assault frequency and the penetration probability of the $\alpha$ particle by means of the Wentzel-Kramers-Brillouin approximation in combination with the Bohr-Sommerfeld quantization condition. The correlation of the $\alpha$-particle preformation probability and the neutron and proton level sequences of the parent nucleus as obtained in our previous work is extended to odd-even and odd-odd nuclei to determine the nuclear spin and parities. Two spin coupling rules are used, namely, strong and weak rules to determine the nuclear spin for odd-odd isotopes. This work can be a useful reference for theoretical calculation of undetermined nuclear spin of odd-odd nuclei in the future.

Several methods of generating three constituent quarks in a nucleon are evaluated which explicitly maintain the nucleon's center of mass and desired radial distribution and can be used within Monte Carlo Glauber frameworks. The geometric models provided by each method are used to generate distributions over the number of constituent quark participants $\left(N_{\mathrm{qp}}\right)$ in $p+p,d+\mathrm{Au}$, and $\mathrm{Au}+\mathrm{Au}$ collisions. The results are compared with each other and to a previous result of $N_{\mathrm{qp}}$ calculations, without this explicit constraint, used in measurements of $\sqrt{s_{{}_{NN}}}=200$ GeV $p+p,d+\mathrm{Au}$, and $\mathrm{Au}+\mathrm{Au}$ collisions at the BNL Relativistic Heavy Ion Collider.

We present predictions from the string melting version of a multiphase transport model on various observables in Pb+Pb collisions at $\sqrt{s_{\mathit{NN}}}=5.02\mathrm{TeV}$. We use the same version of the model as an earlier study that reasonably reproduced $dN/dy$, $p_T$ spectra and elliptic flow of charged pions and kaons at low-$p_T$ for central and semicentral heavy ion collisions at 200 GeV and 2.76 TeV. While we compare with the already-available centrality dependence data on charged particle $dN/d\eta$ at mid-pseudorapidity in Pb+Pb collisions at 5.02 TeV, we make predictions on identified particle $dN/dy$, $p_T$ spectra, azimuthal anisotropies $v_n(n=2,3,4)$, and factorization ratios $r_n({\eta }^a,{\eta }^b)(n=2,3)$ for longitudinal correlations.

The pole extrapolation method is applied to the semi-inclusive inelastic electron scattering off the deuteron with tagged spectator protons to extract the high-$x$ structure function of the neutron. This approach is based on the extrapolation of the measured cross sections at different momenta of the spectator proton to the nonphysical pole of the bound neutron in the deuteron. The advantage of the method is in the possibility of suppression of the nuclear effects in a maximally model-independent way. The neutron structure functions obtained in this way demonstrate a surprising $x$ dependence at $x\ge 0.6$ and $1.6\le Q^2\le 3.38{\mathrm{GeV}}^2$, indicating a possible rise of the neutron-to-proton structure functions ratio. If the observed rise is valid in the true deep inelastic region then it may indicate new dynamics in the generation of high-$x$ quarks in the nucleon. One such mechanism we discuss is the possible dominance of short-range isosinglet quark-quark correlations that can enhance the $d$-quark distribution in the proton.

Properties of hot and dense matter are calculated in the framework of quantum hadrodynamics by including contributions from two-loop (TL) diagrams arising from the exchange of isoscalar and isovector mesons between nucleons. Our extension of mean field theory (MFT) employs the same five density-independent coupling strengths which are calibrated using the empirical properties at the equilibrium density of isospin-symmetric matter. Results of calculations from the MFT and TL approximations are compared for conditions of density, temperature, and proton fraction encountered in the study of core-collapse supernovae, young and old neutron stars, and mergers of compact binary stars. The TL results for the equation of state (EOS) of cold pure neutron matter at sub- and near-nuclear densities agree well with those of modern quantum Monte Carlo and effective field-theoretical approaches. Although the high-density EOS in the TL approximation for cold and $\beta$-equilibrated neutron-star matter is substantially softer than its MFT counterpart, it is able to support a $2M_{\odot }$ neutron star required by recent precise determinations. In addition, radii of $1.4M_{\odot }$ stars are smaller by $\sim 1$ km than those obtained in MFT and lie in the range indicated by analysis of astronomical data. In contrast to MFT, the TL results also give a better account of the single-particle or optical potentials extracted from analyses of medium-energy proton-nucleus and heavy-ion experiments. In degenerate conditions, the thermal variables are well reproduced by results of Landau's Fermi-liquid theory in which density-dependent effective masses feature prominently. The ratio of the thermal components of pressure and energy density expressed as ${\mathrm{\Gamma }}_{\mathrm{th}}=1+(P_{\mathrm{th}}/{\epsilon }_{\mathrm{th}})$, often used in astrophysical simulations, exhibits a stronger dependence on density than on proton fraction and temperature in both MFT and TL calculations. The prominent peak of ${\mathrm{\Gamma }}_{\mathrm{th}}$ at supranuclear density found in MFT is, however, suppressed in TL calculations. This outcome is analogous to results of nonrelativistic models when exchange contributions from finite-range interactions are included in addition to those of contact interactions.

Background: The CNO cycle is the main energy source in stars more massive than our sun; it defines the energy production and the cycle time that lead to the lifetime of massive stars, and it is an important tool for the determination of the age of globular clusters. In our sun about 1.6% of the total solar neutrino flux comes from the CNO cycle. The largest uncertainty in the prediction of this CNO flux from the standard solar model comes from the uncertainty in the ${}^{14}\mathrm{N}(p,\gamma ){}^{15}\mathrm{O}$ reaction rate; thus, the determination of the cross section at astrophysical temperatures is of great interest.

Purpose: The total cross section of the ${}^{14}\mathrm{N}(p,\gamma ){}^{15}\mathrm{O}$ reaction has large contributions from the transitions to the $E_x=6.79\mathrm{MeV}$ excited state and the ground state of ${}^{15}\mathrm{O}$. The $E_x=6.79\mathrm{MeV}$ transition is dominated by radiative direct capture, while the ground state is a complex mixture of direct and resonance capture components and the interferences between them. Recent studies have concentrated on cross-section measurements at very low energies, but broad resonances at higher energy may also play a role. A single measurement has been made that covers a broad higher-energy range but it has large uncertainties stemming from uncorrected summing effects. Furthermore, the extrapolations of the cross section vary significantly depending on the data sets considered. Thus, new direct measurements have been made to improve the previous high-energy studies and to better constrain the extrapolation.

Methods: Measurements were performed at the low-energy accelerator facilities of the nuclear science laboratory at the University of Notre Dame. The cross section was measured over the proton energy range from $E_p=0.7$ to 3.6 MeV for both the ground state and the $E_x=6.79\mathrm{MeV}$ transitions at ${\theta }_{\text{lab}}=0^{\circ }$, ${45}^{\circ }$, ${90}^{\circ }$, ${135}^{\circ }$, and ${150}^{\circ }$. Both TiN and implanted-${}^{14}\mathrm{N}$ targets were utilized. $\gamma$ rays were detected by using an array of high-purity germanium detectors.

Results: The excitation function as well as angular distributions of the two transitions were measured. A multichannel $R$-matrix analysis was performed with the present data and is compared with previous measurements. The analysis covers a wide energy range so that the contributions from broad resonances and direct capture can be better constrained.

Conclusion: The astrophysical $S$ factors of the $E_x=6.79\mathrm{MeV}$ and the ground-state transitions were extrapolated to low energies with the newly measured differential-cross-section data. Based on the present work, the extrapolations yield $S_{6.79}\left(0\right)=1.29\pm 0.04\left(\mathrm{stat}\right)\pm 0.09\left(\mathrm{syst}\right)\mathrm{keV}\mathrm{b}$ and $S_{\text{g.s.}}\left(0\right)=0.42\pm 0.04\left(\mathrm{stat}\right)\mathrm{keV}\mathrm{b}$. While significant improvement and consistency is found in modeling the $E_x=6.79\mathrm{MeV}$ transition, large inconsistencies in both the $R$-matrix fitting and the low-energy data are reaffirmed for the ground-state transition. Reflecting this, a systematic uncertainty of ${}_{-0.19}^{+0.09}\mathrm{keV}\mathrm{b}$ is recommended for the ground-state transition.

Background: Radii of charge and neutron distributions are fundamental nuclear properties. They depend on both nuclear interaction parameters related to the equation of state of infinite nuclear matter and on quantal shell effects, which are strongly impacted by the presence of nuclear surface.

Purpose: In this work, by studying the correlation of charge and neutron radii, and neutron skin, with nuclear matter parameters, we assess different mechanisms that drive nuclear sizes.

Method: We apply nuclear density functional theory using a family of Skyrme functionals obtained by means of optimization protocols, which do not include any radius information. By performing the Monte Carlo sampling of reasonable functionals around the optimal parametrization, we scan all correlations between nuclear matter properties and observables characterizing charge and neutron distributions of spherical closed-shell nuclei ${}^{48}\mathrm{Ca},{}^{208}\mathrm{Pb}$, and ${}^{298}\mathrm{Fl}$.

Results: By considering the influence of various nuclear matter properties on charge and neutron radii in a multidimensional parameter space of Skyrme functionals, we demonstrate the existence of two strong relationships: (i) between the nuclear charge radii and the saturation density of symmetric nuclear matter ${\rho }_0$, and (ii) between the neutron skins and the slope of the symmetry energy $L$. The impact of other nuclear matter properties on nuclear radii is weak or nonexistent. For functionals optimized to experimental binding energies only, proton and neutron radii are found to be weakly correlated due to canceling trends from different nuclear matter characteristics.

Conclusion: The existence of only two strong relations connecting nuclear radii with nuclear matter properties has important consequences. First, by requiring that the nuclear functional reproduces the empirical saturation point of symmetric nuclear matter practically fixes the charge (or proton) radii, and vice versa. This explains the recent results of ab initio calculations with two-nucleon and three-nucleon forces optimized simultaneously to binding energies and radii of selected nuclei. Second, since the neutron skin uncertainty primarily depends on the slope of the symmetry energy, imposing constraints on both ${\rho }_0$ and $L$ practically determines the nuclear size, modulo small variations due to shell effects.

Background: It is generally acknowledged that the time-dependent Hartree–Fock (TDHF) method provides a useful foundation for a fully microscopic many-body theory of low-energy heavy ion reactions. The TDHF method is also known in nuclear physics in the small-amplitude domain, where it provides a useful description of collective states, and is based on the mean-field formalism, which has been a relatively successful approximation to the nuclear many-body problem. Currently, the TDHF theory is being widely used in the study of fusion excitation functions, fission, and deep-inelastic scattering of heavy mass systems, while providing a natural foundation for many other studies.

Purpose: With the advancement of computational power it is now possible to undertake TDHF calculations without any symmetry assumptions and incorporate the major strides made by the nuclear structure community in improving the energy density functionals used in these calculations. In particular, time-odd and tensor terms in these functionals are naturally present during the dynamical evolution, while being absent or minimally important for most static calculations. The parameters of these terms are determined by the requirement of Galilean invariance or local gauge invariance but their significance for the reaction dynamics have not been fully studied. This work addresses this question with emphasis on the tensor force.

Method: The full version of the Skyrme force, including terms arising only from the Skyrme tensor force, is applied to the study of collisions within a completely symmetry-unrestricted TDHF implementation.

Results: We examine the effect on upper fusion thresholds with and without the tensor force terms and find an effect on the fusion threshold energy of the order several MeV. Details of the distribution of the energy within terms in the energy density functional are also discussed.

Conclusions: Terms in the energy density functional linked to the tensor force can play a non-negligible role in dynamic processes in nuclei.

We propose an extension to classify jet modification in heavy-ion collisions by including the jet mass along with its energy. The mass of a jet, as measured by jet reconstruction algorithms, is constrained by the jet's virtuality, which in turn has a considerable effect on such observables as the fragmentation function and jet shape observables. The leading parton, propagating through a dense medium, experiences substantial virtuality (or mass) depletion along with energy loss. Meaningful comparisons between surviving jets and jets produced in $p\text{−}p$ collisions require mass depletion to be taken into account. Using a vacuum event generator, we show the close relationship between the actual jet mass and that after applying a jet reconstruction algorithm. Using an in-medium event generator, we demonstrate the clear difference between the mass of a surviving parton exiting a dense medium and a parton with a similar energy formed in a hard scattering event. Effects of this difference on jet observables are discussed.

We present a symmetry-based approach for prolate-oblate and spherical-prolate-oblate shape coexistence, in the framework of the interacting boson model of nuclei. The proposed Hamiltonian conserves the SU(3) and $\overline{\mathrm{SU}\left(3\right)}$ symmetry for the prolate and oblate ground bands and the U(5) symmetry for selected spherical states. Analytic expressions for quadrupole moments and $E2$ rates involving these states are derived and isomeric states are identified by means of selection rules.

We describe and implement twisted boundary conditions for the deuteron and triton systems within finite volumes using the nuclear lattice EFT formalism. We investigate the finite-volume dependence of these systems with different twist angles. We demonstrate how various finite-volume information can be used to improve calculations of binding energies in such a framework. Our results suggests that with appropriate twisting of boundaries, infinite-volume binding energies can be reliably extracted from calculations using modest volume sizes with cubic length $L\approx 8–14$ fm. Of particular importance is our derivation and numerical verification of three-body analogs of “i-periodic” twist angles that eliminate the leading-order finite-volume effects to the three-body binding energy.

Brieva-Rook approximations for calculating the equivalent local microscopic nucleon-nucleus spin-orbit potential has been examined in the energy region of $65<E<500\mathrm{MeV}$. We present an exact method for calculating both the direct and the exchange parts of the spin-orbit potential. It has been shown that the series expansion used earlier overestimates both the real and the imaginary parts by about $50\%$. Our results show that the exchange contribution to the total spin-orbit potential at low energies is only $15\%$ (much smaller than earlier estimates) and becomes negligible around 200-MeV nucleon incident energy. Predictions of the new spin-orbit potential with minor scaling has been found to be in fair agreement with $p\text{−}{}^{208}\mathrm{Pb}$ scattering observables from 65 to 500 MeV.

Residual nuclei formed at ground and isomeric states from the interaction of 4.4 GeV deuteron with a gold target have been measured and investigated by the induced-activity method. Eight isomeric and ground-state pairs of target residues in the mass range of $44<A<198$ were identified by off-line $\gamma$-spectroscopy analysis and their isomer ratios were obtained from the cross-section production. From the isomer ratio data of the formed ${}^{196}\mathrm{Au}$ and ${}^{197}\mathrm{Hg}$ nuclei, the average intrinsic angular momentum of the composite system was estimated by means of a simple statistical model based on the formalism developed by Huizenga and Vandenbosch.