We present a computation of elastic energy loss of hard partons traversing the bulk hydrodynamical medium created in ultrarelativistic heavy-ion collisions. The model is based on perturbative QCD (pQCD) cross sections for $2\to 2$ processes in which a hard incoming parton is assumed to interact with a thermal parton from the medium. We model the interactions of this type in a Monte-Carlo framework to account properly for exact energy-momentum conservation, noneikonal parton propagation, parton conversion reactions, and the possibility to create additional hard recoiling partons from the medium. For the thermodynamical properties of the medium we use a hydrodynamical evolution model. We do not aim at a full description of high transverse momentum ($P_T$) observables at this point. Rather, we view the model as a starting point in obtaining a baseline of what to expect under the assumptions that the medium is describable by thermal quasifree partons and that their pQCD interactions with the high-energy partons are independent. Deviations from this baseline then call for a more sophisticated medium description, as well as inclusion of higher-order processes and coherence effects in the pQCD scatterings.

The $\beta$ decays of very neutron-rich nuclides in the Co–Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL $\beta$-counting station in conjunction with the neutron detector NERO. We measured the branchings for $\beta$-delayed neutron emission ($P_n$ values) for ${}^{74}\mathrm{Co}$ ($18\pm 15\%$) and ${}^{75-77}\mathrm{Ni}$ ($10\pm 2.8\%$, $14\pm 3.6\%$, and $30\pm 24\%$, respectively) for the first time, and remeasured the $P_n$ values of ${}^{77-79}\mathrm{Cu}$, ${}^{79,81}\mathrm{Zn}$, and ${}^{82}\mathrm{Ga}$. For ${}^{77-79}\mathrm{Cu}$ and for ${}^{81}\mathrm{Zn}$ we obtain significantly larger $P_n$ values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of ${}^{75}\mathrm{Co}$ ($30\pm 11$ ms) and ${}^{80}\mathrm{Cu}$ (${170}_{-50}^{+110}$ ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process ($r$-process) is explored. We find that with our new data, the classical $r$-process model is better able to reproduce the $A=78–80$ abundance pattern inferred from the solar abundances. The new data also influence $r$-process models based on the neutrino-driven high-entropy winds in core collapse supernovae.

Since the identification of ongoing ${}^{26}\mathrm{Al}$ production in the universe, the reaction sequence ${}^{24}\mathrm{Mg}$($p,\gamma$)${}^{25}\mathrm{Al}$(${\beta }^{+}\nu$)${}^{25}\mathrm{Mg}$($p,\gamma$)${}^{26}\mathrm{Al}$ has been studied intensively. At temperatures where the radiative capture on ${}^{25}\mathrm{Al}$ ($t_{1/2}=7.2$ s) becomes faster than the ${\beta }^{+}$ decay, the production of ${}^{26}\mathrm{Al}$ can be reduced due to the depletion of ${}^{25}\mathrm{Al}$. To determine the resonances relevant for the ${}^{25}\mathrm{Al}$($p,\gamma$)${}^{26}\mathrm{Si}$ bypass reaction, we measured the ${}^{28}\mathrm{Si}(p,t){}^{26}\mathrm{Si}$ reaction with high-energy precision using the Grand Raiden spectrometer at the Research Center for Nuclear Physics, Osaka. Several new energy levels were found above the $p$ threshold and for known states excitation energies were determined with smaller uncertainties. The calculated stellar rates of the bypass reaction agree well with previous results, suggesting that these rates are well established.

The equations which relate three-body and two-body symmetry violating scattering amplitudes are derived in the first order of symmetry violating interactions. They can be used to obtain three-body symmetry violating scattering amplitudes from two-body symmetry violating scattering amplitudes calculated in low energy effective field theory.

Pionic quasielastic knockout of protons from nuclei at 200 GeV show very large effects of color transparency as $-t$ increases from 0 to several ${\mathrm{GeV}}^2$. Similar effects are expected for quasielastic photoproduction of vector mesons.

Motivated by a recent astrophysical measurement of the pressure of cold matter above nuclear-matter saturation density, we compute the equation of state of neutron-star matter using accurately calibrated relativistic models. The uniform stellar core is assumed to consist of nucleons and leptons in beta equilibrium; no exotic degrees of freedom are included. We found the predictions of these models to be in fairly good agreement with the measured equation of state. Yet the mass-versus-radius relations predicted by these same models display radii that are consistently larger than the observations.

We report a new measurement of the ${}^8\mathrm{Li}$ half-life using a plastic scintillator and an ultrafast waveform digitizing module. The result, $T_{1/2}=(838.40\pm 0.36$) ms, improves by a factor of 2.5 the most precise result obtained so far and is furthermore deduced with negligible corrections due to dead time.

A neutrino-oscillation analysis is performed of the more finely binned Super-Kamiokande (Super-K) atmospheric, MINOS, and CHOOZ data to examine the effect of neutrino hierarchy in this data set on the value of ${\theta }_{13}$ and the deviation of ${\theta }_{23}$ from maximal mixing. Exact oscillation probabilities are used, thus incorporating all powers of ${\theta }_{13}$ and $\varepsilon :={\theta }_{23}-\pi /4$. The extracted oscillation parameters are found to be dependent on the hierarchy, particularly for ${\theta }_{13}$. We find, at a $90\%$ confidence level, that these parameters are ${\Delta }_{32}=2.{44}_{-0.20}^{+0.26}$ and $2.{48}_{-0.22}^{+0.25}\times {10}^{-3}$ eV${}^2$, $\varepsilon ={\theta }_{23}-\pi /4=0.{06}_{-0.16}^{+0.06}$ and $0.{06}_{-0.17}^{+0.08}$, and ${\theta }_{13}=-0.{07}_{-0.11}^{+0.18}$ and $-0.{13}_{-0.16}^{+0.23}$, for the normal and inverted hierarchies, respectively. The inverted hierarchy is preferred at a statistically insignificant level of $0.3\sigma$.

The $\gamma$-ray strength function is an important input quantity for the determination of the photoreaction rate and the neutron capture rate for astrophysics as well as for nuclear technologies. To test model predictions, the photoabsorption cross section of ${}^{139}\mathrm{La}$ up to the neutron-separation energy was measured using bremsstrahlung produced at the electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf with an electron beam of $11.5$ MeV kinetic energy. The experimental data were analyzed by applying Monte Carlo simulations of $\gamma$-ray cascades to obtain the intensities of the ground-state transitions and their branching ratios. We found a significant enhancement of electric dipole strength in the energy range from $6$ to $10$ MeV that may be related with a pygmy dipole resonance. The present data are combined with photoneutron cross sections for ${}^{139}\mathrm{La}$ and compared with results of calculations on the basis of a quasiparticle-random-phase approximation using an instantaneous-shape sampling.

We carry out three-body-model calculations for a proton-rich Borromean nucleus ${}^{17}\mathrm{Ne}$ by assuming a ${}^{15}\mathrm{O}+p+p$ structure. To this end, we use a density-dependent contact interaction between the valence protons, explicitly treating also the Coulomb interaction. We find that the two-particle density distribution for ${}^{17}\mathrm{Ne}$ is similar to that for ${}^{16}\mathrm{C}$, which has two valence neutrons outside the $N=8$ core. That is, the two protons take a spatially compact configuration, while the Coulomb repulsion plays a minor role. This indicates that there is a strong diproton correlation in the ground state of the ${}^{17}\mathrm{Ne}$ nucleus. We also show that the Coulomb interaction reduces the expectation value of the proton-proton interaction by about $14\%$.

We investigate medium effects caused by density-dependent magnetic moments of baryons on neutron stars under strong magnetic fields. If we allow the variation of anomalous magnetic moments (AMMs) of baryons in dense matter under strong magnetic fields, AMMs of nucleons are enhanced to be larger than those of hyperons. The enhancement naturally causes the chemical potentials of the baryons to be large and leads to the increase of the proton fraction. Consequently, it causes the suppression of hyperons, resulting in stiffness of the equation of state. Under the presumed strong magnetic fields, we evaluate the relevant particle populations, the equation of state, and the maximum masses of neutron stars by including density-dependent AMMs and compare them with those obtained from AMMs in free space.

The structure of neutron-rich nitrogen nuclei has been studied by use of neutron removal reaction and inelastic scattering. Mass and charge deformations have been deduced for the first excited state of ${}^{21}\mathrm{N}$, which indicates the partial persistence of the $N=14$ subshell closure in nitrogen isotopes. The spectroscopic information obtained on the structure of ${}^{19,21}\mathrm{N}$ confirms the results from a previous experiment.

Excited states in ${}^{115}\mathrm{Pd}$, populated following the ${\beta }^{-}$ decay of ${}^{115}\mathrm{Rh}$ have been studied by means of $\gamma$ spectroscopy after the Penning-trap station at the IGISOL facility, University of Jyväskylä. The $1$$/$$2$${}^{+}$ spin and parity assignment of the ground state of ${}^{115}\mathrm{Pd}$, confirmed in this work, may indicate a transition to an oblate shape in Pd isotopes at high neutron number.

Spin-polarized symmetric nuclear matter is studied within the Dirac-Brueckner-Hartree-Fock approach. We pay particular attention to the difference between the one-body potentials of upward and downward polarized nucleons. This is formally analogous to the Lane potential for isospin-asymmetric nuclear matter. We point out the necessity for additional information on this fundamentally important quantity and suggest ways to constrain it.

Pair correlations in the ground state of ${}^{130}\mathrm{Te}$ have been investigated using pair-transfer experiments to explore the validity of approximations in calculating the matrix element for neutrinoless double-$\beta$ decay. This nucleus is a candidate for the observation of such decay, and a good understanding of its structure is crucial for eventual calculations of the neutrino mass, should such a decay indeed be observed. For proton-pair adding, strong transitions to excited 0${}^{+}$ states had been observed in the Te isotopes by Alford et al. [Nucl. Phys. A 323, 339 (1979)], indicating a breaking of the BCS approximation for protons in the ground state. We measured the neutron-pair removing ($p$,$t$) reaction on ${}^{130}\mathrm{Te}$ and found no indication of a corresponding splitting of the BCS nature of the ground state for neutrons.

The impulse approximation (one-body operator) in the $\mathit{np}\to d{\pi }^0$ reaction is reexamined with emphasis on the issues of reducibility and recoil corrections. An inconsistency when one-pion exchange is included in the production operator is demonstrated and then resolved via the introduction of “wave function corrections” which nearly vanish for static nucleon propagators. Inclusion of the recoil corrections to the nucleon propagators is found to change the magnitude and sign of the impulse production amplitude, worsening agreement with the experimental cross section by $~30\%$. A cutoff is used to account for the phenomenological nature of the external wave functions and is found to have a significant impact for $\Lambda \lesssim 2.5$ GeV.