We directly measure the absolute cross section of ${}^{11}\mathrm{B}(p,\gamma ){}^{12}\mathrm{C}$ in the energy region of $E_{\mathrm{c}.\mathrm{m}.}=130$–257 keV by using a thin target for the first time. This work is performed on a 320-kV platform at the Institute of Modern Physics in Lanzhou. The astrophysical $S$ factors of this reaction are obtained for capture to the ground and first excited states of ${}^{12}\mathrm{C}$. The properties of the known resonance at $\sim 150$ keV are derived and agree with the previous results. However, in the energy region of 170–240 keV, our $S$ factors are about 15%–50% larger than the adopted values in NACRE II and are also larger than the upper limits of NACRE II by up to $\sim 20\%$. This indicates that our new reaction rate is enhanced by about 15%–50% compared to the NACRE II adopted rate in the temperature region 0.32–0.62 GK.

We report on a new measurement of the $g$ factor of the ($13/2{}^{+}$) isomeric state in the neutron-rich nucleus ${}^{69}\mathrm{Cu}$. This study demonstrates the possibility of obtaining considerable nuclear spin alignment for multi-quasiparticle states in single-nucleon removal reactions. The time-dependent perturbed angular distribution (TDPAD) method was used to extract the gyromagnetic factor of the ($13/2^{+}$) $[T_{1/2}=351\left(14\right)$ ns] isomeric state of ${}^{69}\mathrm{Cu}$. Its $g$ factor was obtained as $g(13/2^{+})=0.248\left(9\right)$. The experimentally observed spin alignment for the state of interest was deduced as $A=-3.3\left(9\right)\%$.

We calculate the properties of isospin-asymmetric nuclear matter based on chiral nucleon-nucleon (NN) and three-nucleon (3N) interactions. To this end, we develop an improved normal-ordering framework that allows us to include general 3N interactions starting from a plane-wave partial-wave-decomposed form. We present results for the energy per particle for general isospin asymmetries based on a set of different Hamiltonians, study their saturation properties, the incompressibility, symmetry energy, and also provide an analytic parametrization for the energy per particle as a function of density and isospin asymmetry.

Background: Low-energy transfer reactions in which a proton is stripped from a deuteron projectile and dropped into a target play a crucial role in the formation of nuclei in both primordial and stellar nucleosynthesis, as well as in the study of exotic nuclei using radioactive beam facilities and inverse kinematics. Ab initio approaches have been successfully applied to describe the ${}^3\mathrm{H}(d,n){}^4\mathrm{He}$ and ${}^3\mathrm{He}(d,p){}^4\mathrm{He}$ fusion processes.

Purpose: An ab initio treatment of transfer reactions would also be desirable for heavier targets. In this work, we extend the ab initio description of $(d,p)$ reactions to processes with light $p$-shell nuclei. As a first application, we study the elastic scattering of deuterium on ${}^7\mathrm{Li}$ and the ${}^7\mathrm{Li}(d,p){}^8\mathrm{Li}$ transfer reaction based on a two-body Hamiltonian.

Methods: We use the no-core shell model to compute the wave functions of the nuclei involved in the reaction, and describe the dynamics between targets and projectiles with the help of microscopic-cluster states in the spirit of the resonating group method.

Results: The shapes of the excitation functions for deuterons impinging on ${}^7\mathrm{Li}$ are qualitatively reproduced up to the deuteron breakup energy. The interplay between $d-{}^7\mathrm{Li}$ and $p-{}^8\mathrm{Li}$ particle-decay channels determines some features of the ${}^9\mathrm{Be}$ spectrum above the $d+{}^7\mathrm{Li}$ threshold. Our prediction for the parity of the 17.298 MeV resonance is at odds with the experimental assignment.

Conclusions: Deuteron stripping reactions with $p$-shell targets can now be computed ab initio, but calculations are very demanding. A quantitative description of the ${}^7\mathrm{Li}(d,p){}^8\mathrm{Li}$ reaction will require further work to include the effect of three-nucleon forces and additional decay channels and to improve the convergence rate of our calculations.

We present a reanalysis of the data from Stanford Linear Accelerator Center (SLAC) experiments E140 [R. C. Walker et al., Phys. Rev. D 49, 5671 (1994)] and NE11 [L. Andivahis et al., Phys. Rev. D 50, 5491 (1994)] on elastic electron-proton scattering. This work is motivated by recent progress in calculating the corresponding radiative corrections and by the apparent discrepancy between the Rosenbluth and polarization transfer measurements of the proton electromagnetic form factors. New, corrected values for the scattering cross sections are presented, as well as a new form factor fit in the $Q^2$ range from 1 to 8.83 ${\text{GeV}}^2$. We also provide a complete set of revised formulas to account for radiative corrections in single-arm measurements of unpolarized elastic electron-proton scattering.

Background: The ${}^{22}\mathrm{Ne}(\alpha ,n){}^{25}\mathrm{Mg}$ reaction is the dominant neutron source for the slow neutron capture process ($s$ process) in massive stars, and contributes, together with ${}^{13}\mathrm{C}(\alpha ,n){}^{16}\mathrm{O}$, to the production of neutrons for the $s$ process in asymptotic giant branch (AGB) stars. However, the reaction is endothermic and competes directly with ${}^{22}\mathrm{Ne}(\alpha ,\gamma ){}^{26}\mathrm{Mg}$ radiative capture. The uncertainties for both reactions are large owing to the uncertainty in the level structure of ${}^{26}\mathrm{Mg}$ near the $\alpha$ and neutron separation energies. These uncertainties affect the $s$-process nucleosynthesis calculations in theoretical stellar models.

Purpose: Indirect studies in the past have been successful in determining the energies and the $\gamma$-ray and neutron widths of the ${}^{26}\mathrm{Mg}$ states in the energy region of interest. But, the high Coulomb barrier hinders a direct measurement of the resonance strengths, which are determined by the $\alpha$ widths for these states. The goal of the present experiments is to identify the critical resonance states and to precisely measure the $\alpha$ widths by $\alpha$-transfer techniques.

Methods: The $\alpha$-inelastic scattering and $\alpha$-transfer measurements were performed on a solid ${}^{26}\mathrm{Mg}$ target and a ${}^{22}\mathrm{Ne}$ gas target, respectively, using the Grand Raiden Spectrometer at the Research Center for Nuclear Physics in Osaka, Japan. The $(\alpha ,{\alpha }^{\prime })$ measurements were performed at $0.{45}^{\circ }, 4.1^{\circ }, 8.6^{\circ }$, and $11.1^{\circ }$ and the $({}^6\mathrm{Li},d)$ measurements at $0^{\circ }$ and ${10}^{\circ }$. The scattered $\alpha$ particles and deuterons were detected by the focal plane detection system consisting of multiwire drift chambers and plastic scintillators. The focal plane energy calibration allowed the study of ${}^{26}\mathrm{Mg}$ levels from $E_x$ = 7.69–12.06 MeV in the $(\alpha ,{\alpha }^{\prime })$ measurement and $E_x$ = 7.36–11.32 MeV in the $({}^6\mathrm{Li},d)$ measurement.

Results: Six levels ($E_x$ = 10717, 10822, 10951, 11085, 11167, and 11317 keV) were observed above the $\alpha$ threshold in the region of interest (10.61–11.32 MeV). The $\alpha$ widths were calculated for these states from the experimental data. The results were used to determine the $\alpha$-capture induced reaction rates.

Conclusion: The energy range above the $\alpha$ threshold in ${}^{26}\mathrm{Mg}$ was investigated using a high resolution spectrometer. A number of states were observed for the first time in $\alpha$-scattering and $\alpha$-transfer reactions. The excitation energies and spin-parities were determined. Good agreement is observed for previously known levels in ${}^{26}\mathrm{Mg}$. From the observed resonance levels the $E_x$ = 10717 keV state has a negligible contribution to the $\alpha$-induced reaction rates. The rates are dominated in both reaction channels by the resonance contributions of the states at $E_x$ = 10951, 11167, and 11317 keV. The $E_x$ = 11167 keV state has the most appreciable impact on the $(\alpha ,\gamma )$ rate and therefore plays an important role in the prediction of the neutron production in $s$-process environments.

Recently published study on the $\gamma$-ray energy dependence of photon strength functions (PSFs) from the population of ${}^{95}\mathrm{Mo}$ low-lying levels in the ${}^{94}\mathrm{Mo}(d,p\gamma \gamma ){}^{95}\mathrm{Mo}$ reaction set out to answer some important questions related to the PSFs below the neutron separation energy in the Mo region. In this paper we discuss in detail actual relations of the quantities measured in this reaction to the PSFs and check the consistency of several available PSF models with experimental data. A broad variety of models was found to be consistent with experimental data at low $E_{\gamma }$. Although the photon strength very likely increases with decreasing energy at $E_{\gamma }\lesssim 3$ MeV, the data are unable to clearly differentiate whether the decrease follows the shape proposed from Oslo-type experiments or predictions of the generalized Lorentzian $E1$ model. The PSF shape at energies of $5\text{–}7$ MeV is steeper than predicted by any standard model.

The occurrence of the bubble-like structure has been studied, in the light of pseudospin degeneracy, within the relativistic Hartree-Fock-Bogoliubov (RHFB) theory. It is concluded that the charge/neutron bubble-like structure is predicted to occur in the mirror system of {${}^{34}\mathrm{Si},{}^{34}\mathrm{Ca}$} commonly by the selected Lagrangians, due to the persistence of $Z\left(N\right)=14$ subshell gaps above which the $\pi \left(\nu \right)2s_{1/2}$ states are not occupied. However, for the popular candidate ${}^{46}\mathrm{Ar}$, the RHFB Lagrangian PKA1 does not support the occurrence of the bubble-like structure in the charge (proton) density profiles, due to the almost degenerate pseudospin doublet $\{\pi 2s_{1/2},\pi 1d_{3/2}\}$ and coherent pairing effects. The formation of a semibubble in heavy nuclei is less possible as a result of small pseudospin-orbit (PSO) splitting, while it tends to appear at $Z=120$ superheavy systems which coincides with large PSO splitting of the doublet $\{\pi 3p_{3/2},\pi 2f_{5/2}\}$ and couples with significant shell effects. Pairing correlations, which can work against bubble formation, significantly affect the PSO splitting. Furthermore, we found that the influence on semibubble formation due to different types of pairing interactions is negligible. The quenching of the spin-orbit splitting in the $p$ orbit has been also stressed, and it may be considered the hallmark for semibubble nuclei.

We study the initial conditions for $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV using the two-component Monte-Carlo Glauber model with shadowing of the nucleons in the interior by the leading ones. The model parameters are fixed by comparing them to the multiplicity data of $p+\mathrm{Pb}$ and $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02$ and $2.76$ TeV, respectively. We then compute the centrality dependence of the eccentricities up to the fourth order as well as their event-by-event distributions. The inclusion of shadowing brings the Monte-Carlo Glauber model predictions in agreement with data as well as with results from other dynamical models of initial conditions based on gluon saturation at high-energy nuclear collisions. Further, we find that the shadowed Glauber model provides the desired relative magnitude between the ellipticity and the triangularity of the initial energy distribution required to explain the data on the even and odd flow harmonics $v_2$ and $v_3$, respectively, at the CERN Large Hadron Collider.

$J/\psi$ suppression with rapidity is studied with both a (3+1)-dimensional transport equation and hydrodynamics in detail at $\sqrt{s_{NN}}=2.76$ TeV Pb+Pb collisions. In the central rapidity region of the hot medium, the $J/\psi$ nuclear modification factor shows weak rapidity dependence due to the boost invariance of the medium. But in the forward rapidity region for the entire transverse momentum bin, $J/\psi$ regeneration is strongly suppressed due to the decreasing charm pair cross section. This makes $J/\psi R_{AA}\left(y\right)$ decrease with rapidity. The ratio $r_{AA}$ of the mean transverse momentum squared in $AA$ collisions to that in $pp$ collisions increases strongly in the forward rapidity region and is more sensitive to the $J/\psi$ production mechanisms.

Background: Neutron star and supernova matter at densities just below the nuclear matter saturation density is expected to form a lattice of exotic shapes. These so-called nuclear pasta phases are caused by Coulomb frustration. Their elastic and transport properties are believed to play an important role for thermal and magnetic field evolution, rotation, and oscillation of neutron stars. Furthermore, they can impact neutrino opacities in core-collapse supernovae.

Purpose: In this work, we present proof-of-principle three-dimensional (3D) Skyrme Hartree-Fock (SHF) simulations of nuclear pasta with the Multi-resolution ADaptive Numerical Environment for Scientific Simulations (MADNESS).

Methods: We perform benchmark studies of ${}^{16}\mathrm{O}, {}^{208}\mathrm{Pb}$, and ${}^{238}\mathrm{U}$ nuclear ground states and calculate binding energies via 3D SHF simulations. Results are compared with experimentally measured binding energies as well as with theoretically predicted values from an established SHF code. The nuclear pasta simulation is initialized in the so-called waffle geometry as obtained by the Indiana University Molecular Dynamics (IUMD) code. The size of the unit cell is 24 fm with an average density of about $\rho =0.05{\mathrm{fm}}^{-3}$, proton fraction of $Y_p=0.3$, and temperature of $T=0$ MeV.

Results: Our calculations reproduce the binding energies and shapes of light and heavy nuclei with different geometries. For the pasta simulation, we find that the final geometry is very similar to the initial waffle state. We compare calculations with and without spin-orbit forces. We find that while subtle differences are present, the pasta phase remains in the waffle geometry.

Conclusions: Within the MADNESS framework, we can successfully perform calculations of inhomogeneous nuclear matter. By using pasta configurations from IUMD it is possible to explore different geometries and test the impact of self-consistent calculations on the latter.

The isospin-asymmetry dependence of the nuclear-matter equation of state obtained from microscopic chiral two- and three-body interactions in second-order many-body perturbation theory is examined in detail. The quadratic, quartic, and sextic coefficients in the Maclaurin expansion of the free energy per particle of infinite homogeneous nuclear matter with respect to the isospin asymmetry are extracted numerically using finite differences, and the resulting polynomial isospin-asymmetry parametrizations are compared to the full isospin-asymmetry dependence of the free energy. It is found that in the low-temperature and high-density regime where the radius of convergence of the expansion is generically zero, the inclusion of higher-order terms beyond the leading quadratic approximation leads overall to a significantly poorer description of the isospin-asymmetry dependence. In contrast, at high temperatures and densities well below nuclear saturation density, the interaction contributions to the higher-order coefficients are negligible and the deviations from the quadratic approximation are predominantly from the noninteracting term in the many-body perturbation series. Furthermore, we extract the leading logarithmic term in the isospin-asymmetry expansion of the equation of state at zero temperature from the analysis of linear combinations of finite differences. It is shown that the logarithmic term leads to a considerably improved description of the isospin-asymmetry dependence at zero temperature.

We present ab initio predictions for ground and excited states of doubly open-shell fluorine and neon isotopes based on chiral two- and three-nucleon interactions. We use the in-medium similarity renormalization group to derive mass-dependent $sd$ valence-space Hamiltonians. The experimental ground-state energies are reproduced through neutron number $N=14$, beyond which a new targeted normal-ordering procedure improves agreement with data and large-space multireference calculations. For spectroscopy, we focus on neutron-rich ${}^{23-26}\mathrm{F}$ and ${}^{24-26}\mathrm{Ne}$ isotopes near $N=14,16$ magic numbers. In all cases we find agreement with experiment and established phenomenology. Moreover, yrast states are well described in ${}^{20}\mathrm{Ne}$ and ${}^{24}\mathrm{Mg}$, providing a path toward an ab initio description of deformation in the medium-mass region.

The correlations between global description of the ground state properties (binding energies, charge radii) and nuclear matter properties of the state-of-the-art covariant energy density functionals have been studied. It was concluded that the strict enforcement of the constraints on the nuclear matter properties (NMP) defined in Dutra et al. [Phys. Rev. C 90, 055203 (2014)] will not necessarily lead to the functionals with good description of the binding energies and other ground and excited state properties. In addition, it will not substantially reduce the uncertainties in the predictions of the binding energies in neutron-rich systems. It turns out that the functionals, which come close to satisfying these NMP constraints, have some problems in the description of existing data. On the other hand, these problems are either absent or much smaller in the functionals which are carefully fitted to finite nuclei but which violate some NMP constraints. This is a consequence of the fact that the properties of finite nuclei are defined not only by nuclear matter properties but also by underlying shell effects. The mismatch of phenomenological content, existing in all modern functionals, related to nuclear matter physics and the physics of finite nuclei could also be responsible.

The photodisintegration of ${}^9\mathrm{Be}$ in the energy region lower than $E_{\gamma }=16$ MeV is investigated by using the $\alpha + \alpha + n$ three-body model and the complex scaling method. The cross section exhibits two aspects in two different energy regions. In the low-energy region up to $E_{\gamma }=6$ MeV, the cross section is explained by the transition strengths into the excited resonant states of ${}^9\mathrm{Be}$, while the dipole transition into the nonresonant continuum states of ${}^8\mathrm{Be}\left(2^{+}\right) + n$ dominates the cross section in the energy region of $6\le E_{\gamma }\le 16$ MeV. Furthermore, it is shown that the dipole strength at $E_{\gamma }\sim 8$ MeV is understood to be caused by the single-neutron excitation from the ${}^8\mathrm{Be}\left(2^{+}\right)\otimes \nu p_{3/2}$ configuration in the ground state.

The isoscalar monopole (ISM) and dipole (ISD) excitations in ${}^{12}\mathrm{C}$ are investigated theoretically with the shifted antisymmetrized molecular dynamics (AMD) plus $3\alpha$-cluster generator coordinate method (GCM). The small-amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by a small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large-amplitude cluster modes are incorporated by superposing $3\alpha$-cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present a calculation that describes the ISM and ISD excitations over a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, although the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster modes are enhanced by the distance motion between $\alpha$ clusters, and they split into a couple of states because of the angular motion of $\alpha$ clusters. The low-energy ISM strengths exhaust 26% of the energy-weighted sum rule, which is consistent with the experimental data for the ${}^{12}\mathrm{C}$($0_2^{+}$; 7.65 MeV) and ${}^{12}\mathrm{C}$($0_3^{+}$; 10.3 MeV) measured by $(e,e^{\prime }),(\alpha ,{\alpha }^{\prime })$, and (${}^6\mathrm{Li},\stackrel{\prime }{{}^6\mathrm{Li}}$) scatterings. In the calculated low-energy ISD strengths, two $1^{-}$ states (the $1_1^{-}$ and $1_2^{-}$ states) with the significant strengths are obtained over $E=10\text{–}15$ MeV. The results indicate that the ISD excitations can be a good probe to experimentally search for new cluster states such as the ${}^{12}\mathrm{C}\left(1_2^{-}\right)$ obtained in the present calculation.

We extend the concept of nonlocalized clustering to the nucleus ${}^{10}\mathrm{Be}$ with proton number $Z=4$ and neutron number $N=6 \left(N=Z+2\right)$. The Tohsaki-Horiuchi-Schuck-Röpke (THSR) wave function is formulated for the description of different structures of ${}^{10}\mathrm{Be}$. Physical properties such as energy spectrum and root-mean-square radii are calculated for the first two $0^{+}$ states and corresponding rotational bands. With only one single THSR wave function, the calculated results show good agreement with other models and experimental values. We apply, for the first time, the THSR wave function on the chain orbit ($\sigma$-orbit) structure in the $0_2{}^{+}$ state of ${}^{10}\mathrm{Be}$. The ring-orbit ($\pi$-orbit) and $\sigma$-orbit structures are further illustrated by calculating the density distribution of the valence neutrons. We also investigate the nonlocalized dynamics of $\alpha$ clusters and the correlations of two valence neutrons in ${}^{10}\mathrm{Be}$.