Complete and incomplete fusion cross sections for ${}^6\mathrm{Li}$ $+$ ${}^{159}\mathrm{Tb}$ have been measured at energies around the Coulomb barrier by the $\gamma$-ray method. The measurements show that the complete fusion cross sections at above-barrier energies are suppressed by $~$34% compared to coupled-channel calculations. A comparison of the complete fusion cross sections at above-barrier energies with the existing data for ${}^{11,10}\mathrm{B}$ $+$ ${}^{159}\mathrm{Tb}$ and ${}^7\mathrm{Li}$ $+$ ${}^{159}\mathrm{Tb}$ shows that the extent of suppression is correlated with the $\alpha$ separation energies of the projectiles. It has been argued that the Dy isotopes produced in the reaction ${}^6\mathrm{Li}$ $+$ ${}^{159}\mathrm{Tb}$ at below-barrier energies are primarily due to the $d$ transfer to unbound states of ${}^{159}\mathrm{Tb}$, while both transfer and incomplete fusion processes contribute at above-barrier energies.

At large $N_c$, cold nuclear matter is expected to form a crystal and thus spontaneously break translational symmetry. The description of chiral symmetry breaking and translational symmetry breaking can become intertwined. Here, the focus is on aspects of chiral symmetry breaking and its possible restoration that are by construction independent of the nature of translational symmetry breaking—namely spatial averages of chiral order parameters. A system will be considered to be chirally restored provided all spatially averaged chiral order parameters are zero. A critical question is whether chiral restoration in this sense is possible for phases in which chiral order parameters are locally nonzero but whose spatial averages all vanish. We show that this is not possible unless all chirally invariant observables are spatially uniform. This result is first derived for Skyrme-type models, which are based on a nonlinear sigma model and by construction break chiral symmetry on a point-by-point basis. A no-go theorem for chiral restoration (in the average sense) for all models of this type is obtained by showing that in these models there exist chirally symmetric order parameters that cannot be spatially uniform. Next, we will show that the no-go theorem applies to large $N_c$ QCD in any phase that has a nonzero but spatially varying chiral condensate. The theorem is demonstrated by showing that in a putative chirally restored phase, the field configuration can be reduced to that of a nonlinear sigma model. It is also shown that this no-go theorem is fully consistent with the vanishing of the spatial average of the chiral condensate $\frac{1}{2}\mathrm{Tr}(U)$ (as happens in “half-skyrmion” configurations). This is because the chiral condensate is only one of an infinite set of chiral order parameters, some of which must be nonzero. It is also shown that while an approximation of a unit cell of a Skyrme crystal as a hypersphere does lead to a phase that is chirally restored (in the average sense), this is an artifact of the approximation.

A new general expression is derived for nuclear electron capture rates within dense plasmas. Its qualitative nature leads us to question some widely accepted assumptions about how to calculate the effects of the plasma on the rates. A perturbative evaluation, though not directly applicable to the strongly interacting case, appears to bear out these suspicions.

Hadron-quark mixed phase is expected in a wide region of the inner structure of hybrid stars. However, we show that the hadron-quark mixed phase should be restricted to a narrower region because of the charge screening effect. The narrow region of the mixed phase seems to explain physical phenomena of neutron stars such as the strong magnetic field and glitch phenomena, and it would give a new cooling curve for the neutron star.

We report first results from an analysis based on a new multi-hadron correlation technique, exploring jet-medium interactions and di-jet surface emission bias at the BNL Relativistic Heavy Ion Collider (RHIC). Pairs of back-to-back high-transverse-momentum hadrons are used for triggers to study associated hadron distributions. In contrast with two- and three-particle correlations with a single trigger with similar kinematic selections, the associated hadron distribution of both trigger sides reveals no modification in either relative pseudorapidity $\Delta \eta$ or relative azimuthal angle $\Delta \varphi$ from $\text{d}+\text{Au}$ to central $\text{Au}+\text{Au}$ collisions. We determine associated hadron yields and spectra as well as production rates for such correlated back-to-back triggers to gain additional insights on medium properties.

The $\beta$-ray angular correlations for the spin alignments of ${}^8\mathrm{Li}$ and ${}^8\mathrm{B}$ have been observed in order to test the conserved vector current (CVC) hypothesis. The alignment correlation terms were combined with the known $\beta$-$\alpha$ angular correlation terms to determine all the matrix elements contributing to the correlation terms. The weak magnetism term, $7.5\pm 0.2$, deduced from the $\beta$-ray correlation terms was consistent with the CVC prediction $7.3\pm 0.2$, deduced from the analog-$\gamma$ decay measurement based on the CVC hypothesis. However, there was no consistent CVC prediction for the second-forbidden term associated with the weak vector current. The experimental value for the second-forbidden term was $1.0\pm 0.3$, while the CVC prediction was $0.1\pm 0.4$ or $2.1\pm 0.5$.

We present theoretical results for the ${}^{25}\mathrm{Al}$($p,\gamma$)${}^{26}\mathrm{Si}$ resonance-capture rate. The isobaric mass multiplet equation is used to determine the energies and $J^{\pi }$ values of states in ${}^{26}\mathrm{Si}$ based upon those observed in ${}^{26}\mathrm{Mg}$ and ${}^{26}\mathrm{Al}$ together with $\mathit{sd}$ shell calculations for the $c$ coefficients. Three Hamiltonians for the $\mathit{sd}$ shell, USD, USDA and USDB, are used to estimate the theoretical uncertainties in the $\gamma$-decay and proton-decay widths that go into the resonance-capture rate.

Fission fragment angular distributions have been measured for a ${}^9\mathrm{Be}$ $+$ ${}^{232}\mathrm{Th}$ system at four different beam energies around the Coulomb barrier. The experimental results on fission fragment anisotropies have been compared with predictions of the standard statistical saddle-point model (SSPM) and the preequilibrium fission (PEQ) model including projectile ground-state spin. It is observed that both SSPM and the PEQ model fail to reproduce the experimental results, indicating that projectile breakup may affect the fission fragment anisotropies.

We have studied gas-like states of $\alpha$ clusters around an ${}^{16}\mathrm{O}$ core in ${}^{24}\mathrm{Mg}$ based on a microscopic $\alpha$-cluster model. The $0^{+}$ states below the ${}^{16}\mathrm{O}+\alpha +\alpha$ threshold, which are candidates for the resonance solution judging from the energy convergence behavior, are strongly excited by an isoscalar monopole ($E0$) operator from the ground state, which could be observed as an experimental signature of well-developed $\alpha$ gas-like states in the excited states. These states have significant overlaps with the THSR (Tohsaki-Horiuchi-Schuck-Röpke) wave functions with large spatial extension.

We present a study of the effects of the tensor-isospin term of the effective interaction in Hartree-Fock and random-phase approximation calculations. We used finite-range forces of Gogny type, and we added to them a tensor-isospin term which behaves, at large internucleonic distances, as the analogous term of the microscopic interactions. The strength of this tensor force has been chosen to reproduce the experimental energy of the lowest $0^{-}$ excited state in ${}^{16}\mathrm{O}$, which shows large sensitivity to this term of the interaction. With these finite-range interactions, we have studied the effects of the tensor-isospin force in ground and excited states of carbon, oxygen, calcium, nickel, zirconium, tin, and lead isotopes. Our results show that the tensor force affects mainly the nucleon single-particle energies. However, we found some interesting cases where also bulk nuclear properties are sensitive to the tensor interaction.

This paper presents reaction cross-section predictions. These predictions are the result of a continuous pipeline that originates from a microscopic nuclear interaction. Density parameters and effective nucleon-nucleon cross sections (both involved in the reaction calculations) are by-products of the same equation of state. First, we perform tests of sensitivity to medium effects using reactions involving ${}^{208}\mathrm{Pb}$, a stable but weakly isospin-asymmetric nucleus. We also show predictions for collisions of some neutron-rich isotopes of calcium and argon. We observe significant sensitivity of the reaction cross section to medium effects but very weak sensitivity to inclusion of isospin asymmetry in the effective nucleon-nucleon cross sections.

Spin-polarized isospin asymmetric nuclear matter is studied within the Dirac-Brueckner-Hartree-Fock approach. After a brief review of the formalism, we present and discuss the self-consistent single-particle potentials at various levels of spin and isospin asymmetry. We then move to predictions of the energy per particle, also under different conditions of isospin and spin polarization. Comparison with the energy per particle in isospin symmetric or asymmetric unpolarized nuclear matter shows no evidence for a phase transition to a spin-ordered state, neither ferromagnetic nor antiferromagnetic.

Excited states in ${}^{55}\mathrm{V}$ and ${}^{55}\mathrm{Cr}$ have been populated via $\mathit{pn}$ and $2n$ evaporation channels, respectively, following the fusion of a ${}^{48}\mathrm{Ca}$ beam at 172 MeV with a ${}^9\mathrm{Be}$ target. Level schemes have been deduced for the two nuclides to excitation energies of 7467 (${}^{55}\mathrm{V}$) and 12226 keV (${}^{55}\mathrm{Cr}$), with spins of 27/$2^{+}$ and 33/$2^{+}$, respectively. Negative-parity states are compared with shell-model calculations using three different effective interactions in the full $\mathit{fp}$ model space. Negative-parity levels of ${}^{55}\mathrm{Cr}$ are explained in terms of single-particle $\mathit{fp}$-shell configurations outside $N=28$ and $N=32$ cores. Positive-parity states in both isotopes show evidence for the involvement of neutron $g_{9/2}$ configurations. In the case of ${}^{55}\mathrm{Cr}$, a quasirotational structure based on the 1/$2^{+}$[440] Nilsson orbital is observed up to the terminating state. In ${}^{55}\mathrm{V}$, positive-parity states do not exhibit well-developed collective features, and the observation of octupole decays is an indication of their importance in transitions from neutron $g_{9/2}$ configurations to the $\mathit{fp}$ shell. Experimental results are compared with the predictions of a traditional shell model, the projected shell model, and total-Routhian-surface calculations.

The high-spin states of ${}^{141}\mathrm{Pm}$ have been investigated through the reaction ${}^{126}\mathrm{Te}$(${}^{19}\mathrm{F}$,4$n$) at a beam energy of 90 MeV. A previous level scheme has been updated with spins up to 49/2$\hslash$. Six collective bands at high spins are newly observed. Based on the systematic comparison, one band is proposed as a decoupled band; two bands with strong $\Delta I=1$ $M1$ transitions inside the bands are suggested as the oblate bands with $\gamma$ $~$$-{60}^{°}$; three other bands with large signature splitting have been proposed with the oblate-triaxial deformation with $\gamma$$~$ $-{90}^{°}$. The triaxial $n$-particle-$n$-hole particle rotor model calculations for one of the oblate bands in ${}^{141}\mathrm{Pm}$ are in good agreement with the experimental data. The other characteristics for these bands have been discussed.

Accurate measurements of the ${}^8\mathrm{B}$ neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the ${}^8\mathrm{B}$ neutrino spectrum can be obtained from the measurement of the $\beta$-delayed $\alpha$ spectrum. We report on an $\alpha$-$\alpha$ coincidence measurement performed at the IGISOL facility in Jyväskylä, Finland. Our measurement allows extensive cross-checks to be performed and gives a more intense neutrino spectrum at high energies compared to the present standard. The deviation reaches 4% at the end point of the spectrum. Below 11 MeV, the deviation is less than 1%.

We calculate low-energy proton-deuteron scattering in the framework of pionless effective field theory. In the quartet channel, we calculate the elastic scattering phase shift up to next-to-next-to-leading order in the power counting. In the doublet channel, we perform a next-to-leading-order calculation. We obtain good agreement with the available phase-shift analyses down to the scattering threshold. The phase shifts in the region of nonperturbative Coulomb interactions are calculated by using an optimized integration mesh. Moreover, the Coulomb contribution to the ${}^3\mathrm{He}$-${}^3\mathrm{H}$ binding energy difference is evaluated in first-order perturbation theory. We comment on the implications of our results for the power counting of subleading three-body forces.

One plus two-body embedded Gaussian orthogonal ensemble of random matrices with parity [$\mathrm{EGOE}(1+2)-\pi$] generated by a random two-body interaction (modeled by GOE in two-particle spaces) in the presence of a mean field for spinless identical fermion systems is defined, generalizing the two-body ensemble with parity analyzed by Papenbrock and Weidenmüller [Phys. Rev. C 78, 054305 (2008)], in terms of two mixing parameters and a gap between the positive $(\pi =+)$ and negative $(\pi =-)$ parity single-particle (sp) states. Numerical calculations are used to demonstrate, using realistic values of the mixing parameters appropriate for some nuclei, that the $\mathrm{EGOE}(1+2)-\pi$ ensemble generates Gaussian form (with corrections) for fixed parity eigenvalue densities (i.e., state densities). The random matrix model also generates many features in parity ratios of state densities that are similar to those predicted by a method based on the Fermi-gas model for nuclei. We have also obtained, by applying the formulation due to Chang et al. [Ann. Phys. (NY) 66, 137 (1971)], a simple formula for the spectral variances defined over fixed-$(m_1,m_2)$ spaces, where $m_1$ is the number of fermions in the positive parity sp states and $m_2$ is the number of fermions in the negative parity sp states. Similarly, using the binary correlation approximation, in the dilute limit, we have derived expressions for the lowest two-shape parameters. The smoothed densities generated by the sum of fixed-$(m_1,m_2)$ Gaussians with lowest two-shape corrections describe the numerical results in many situations. The model also generates preponderance of positive parity ground states for small values of the mixing parameters, and this is a feature seen in nuclear shell-model results.

The spectrum of strange multibaryons (baryon number $B=2$ and $3$) is considered within the chiral soliton model using one of several possible SU(3) quantization models (the bound state rigid oscillator version). The states with energy below that of an antikaon and its corresponding nucleus can be interpreted as antikaon-nucleus bound states. In the formal limit of small kaon mass the number of such states becomes large, and for a real value of this mass there are at least several states with positive and negative parity in the energy gap of one kaon mass. For large values of binding energies the interpretation of such states as just antikaon-nuclear bound states becomes more ambiguous.

Low-density neutron matter is relevant to the study of neutron-rich nuclei and neutron star crusts. Unpolarized neutron matter has been studied extensively over a number of decades, while experimental guidance has recently started to emerge from the field of ultracold atomic gases. In this work, we study population-imbalanced neutron matter (possibly relevant to magnetars and to density functionals of nuclei) by applying a quantum Monte Carlo method that has proven successful in the field of cold atoms. We report on the first ab initio simulations of superfluid low-density polarized neutron matter. For systems with small imbalances, we find a linear dependence of the energy on the polarization, the proportionality coefficient being dependent on the density. We also present results for the momentum and pair distributions of the two fermionic components.