Background: Deviations between experimental data of charged-particle-induced reactions and calculations within the statistical model are frequently found. An extended data base is needed to address the uncertainties regarding the nuclear-physics input parameters in order to understand the nucleosynthesis of the neutron-deficient $p$ nuclei.

Purpose: A measurement of total cross-section values of the ${}^{130}\mathrm{Ba}(p,\gamma ){}^{131}\mathrm{La}$ reaction at low proton energies allows a stringent test of statistical model predictions with different proton+nucleus optical model potentials. Since no experimental data are available for proton-capture reactions in this mass region around $A \approx 130$, this measurement can be an important input to test the global applicability of proton+nucleus optical model potentials.

Method: The total reaction cross-section values were measured by means of the activation method. After the irradiation with protons, the reaction yield was determined by use of $\gamma$-ray spectroscopy using two clover-type high-purity germanium detectors. In total, cross-section values for eight different proton energies could be determined in the energy range between 3.6 MeV $\le E_p\le$ 5.0 MeV, thus, inside the astrophysically relevant energy region.

Results: The measured cross-section values were compared to Hauser-Feshbach calculations using the statistical model codes TALYS and SMARAGD with different proton+nucleus optical model potentials. With the semimicroscopic JLM proton+nucleus optical model potential used in the SMARAGD code, the absolute cross-section values are reproduced well, but the energy dependence is too steep at the lowest energies. The best description is given by a TALYS calculation using the semimicroscopic Bauge proton+nucleus optical model potential using a constant renormalization factor.

Conclusions: The statistical model calculation using the Bauge semimicroscopic proton+nucleus optical model potential deviates by a constant factor of 2.1 from the experimental data. Using this model, an experimentally supported stellar reaction rate for proton capture on the $p$ nucleus ${}^{130}\mathrm{Ba}$ was calculated. At astrophysical temperatures, an increase in the stellar reaction rate of 68% compared to rates obtained from the widely used NON-SMOKER code is found. This measurement extends the scarce experimental data base for charged-particle-induced reactions, which can be helpful to derive a more globally applicable proton+nucleus optical model potential.

The similarity renormalization group is used to explore the origin and breaking mechanism of the pseudospin symmetry for the relativistic harmonic oscillator. The calculated energies from the diagonal Dirac operator $H_P$ are shown to be in agreement with the exact results. In comparison with the contribution of every term to the pseudospin splitting, the quality of the pseudospin symmetry is revealed from the competition of the dynamical effect and the spin-orbit interaction. The shape of the potentials also has an important influence on the pseudospin symmetry. The dependence of the pseudospin symmetry on the shape of $\Sigma \left(r\right)$ is dominated by the nonrelativistic term, while that of $\Delta \left(r\right)$ is governed by the dynamical term and the spin-orbit interaction.

The complex scaling method is extended to the relativistic framework for describing deformed nuclei and the theoretical formalism is presented in detail. How to expose the resonant states is demonstrated, and the applicability and efficiency of the extended method are confirmed. The energies and widths of the single-particle resonant states in nuclei with $A=31$ are determined, and the structure of single-particle levels for bound and resonant states is shown to be similar to that in the nonrelativistic calculations. Especially, the present formalism has yielded richer numerical results for the resonant levels than those obtained by the coupled-channel method in relativistic and nonrelativistic calculations.

In this paper we discuss the possibility of $J/\psi$ disintegration due to $Z\left(3\right)$ domain walls that are expected to form in a QGP medium. These domain walls give rise to a localized color electric field, which disintegrates $J/\psi$, on interaction, by changing its color composition and simultaneously exciting it to higher states of $c\overline{c}$ system.

The decay of a very long-lived state, such as the famous $J=9^{-}$ isomeric state in ${}^{180}\mathrm{Ta}$, when irradiated by $\gamma$ rays or subjected to Coulomb excitation, can be accelerated by the existence of a doorway state for mixing an excited state of the isomeric band with the states of other bands decaying to the ground state. We describe the mechanism of such a decay similar to the chaos-assisted tunneling.

The rotational bands of $\alpha +{}^{15}\mathrm{O}\left(12^{-}\right)$ in ${}^{19}\mathrm{Ne}$ are calculated by employing a simple potential model. The $\alpha -{}^{15}\mathrm{O}$ interaction potential is constructed from the calculation of the ${}^{20}\mathrm{Ne}=\alpha +{}^{16}\mathrm{O}$ structure and the $\alpha +{}^{15}\mathrm{N}$ elastic scattering. The resonant levels and their decay width are identified by imposing the absorbing boundary condition. The present calculations predict the sequence of the discrete and overlapping resonances in the negative- and positive-parity states of ${}^{19}\mathrm{Ne}$, respectively. The excitation function of the $\alpha +{}^{15}\mathrm{O}$ elastic scattering is also calculated, and the appropriate condition to observe the resonances is discussed.

The structure of the neutron-rich bismuth isotope ${}^{217}\mathrm{Bi}$ has been studied for the first time. The fragmentation of a primary ${}^{238}\mathrm{U}$ beam at the FRS-RISING setup at GSI was exploited to perform $\gamma$-decay spectroscopy, since $\mu s$ isomeric states were expected in this nucleus. Gamma rays following the decay of a $t_{1/2}=3$ $\mu \mathrm{s}$ isomer were observed, allowing one to establish the low-lying structure of ${}^{217}\mathrm{Bi}$. The level energies and the reduced electric quadrupole transition probability $B\left(E2\right)$ from the isomeric state are compared to large-scale shell-model calculations.

High energy photons created from back-scattering of jets in quark gluon plasma are a valuable probe of the temperature of the plasma, and of the energy loss mechanism of quarks in the plasma. An unambiguous identification of these photons through single-inclusive photon measurements and photon azimuthal anisotropies has so far been elusive. We estimate the spectra of back-scattering photons in coincidence with trigger jets for typical kinematic situations at the Large Hadron Collider and the BNL Relativistic Heavy Ion Collider. We find that the separation of back-scattering photons from other photon sources using trigger jets depends crucially on our ability to reliably estimate the initial trigger-jet energy. We estimate that jet-reconstruction techniques in heavy ion experiments need to be able to get to jet $R_{AA}\gtrsim 0.7$ in central collisions for viable back-scattering signals.

Background: The properties of resonances in ${}^{26}\mathrm{Si}$ are important to better constrain the ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction rate relevant to the synthesis of galactic ${}^{26}\mathrm{Al}{}^{\mathrm{gs}}$ and energy generation in explosive stellar environment at higher temperature.

Purpose: ${}^{25}\mathrm{Al}+p$ elastic scattering was measured to further constrain and investigate disagreements in resonance parameters for the high-lying excited states of ${}^{26}\mathrm{Si}$ with high statistics and without background contamination within the target.

Methods: The experiment was performed by bombarding a thick ${\mathrm{H}}_2$ target with an ${}^{25}\mathrm{Al}$ radioactive ion beam. The resonances at excitation energies of 6.6–8.3 MeV in the ${}^{26}\mathrm{Si}$ compound nucleus were studied at the low-energy radioactive-ion beam facility CRIB (Center for Nuclear Study Radioactive Ion Beam separator) at the University of Tokyo.

Results: Six resonant states were observed and their resonance parameters were extracted by an $R$-matrix analysis. Our resonance parameters for two levels are in good agreement with the results of previous studies, while for four others, excitation energy, proton partial width, and spin-parity assignment disagree with the results of recent study via elastic scattering of ${}^{25}\mathrm{Al}+p$.

Conclusion: The parameters of resonant states in ${}^{26}\mathrm{Si}$ determined in the present work for the ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction rate are consistent with that of the previous result, solving spin-parity assignment discrepancies between experiments, relevant at higher temperatures.

Background: In our previous study, we found that an exotic isomer with a torus shape may exist in the high-spin, highly excited states of ${}^{40}\mathrm{Ca}$. The $z$ component of the total angular momentum, $J_z=60\hslash$, of this torus isomer is constructed by totally aligning 12 single-particle angular momenta in the direction of the symmetry axis of the density distribution. The torus isomer executes precession motion with the rigid-body moments of inertia about an axis perpendicular to the symmetry axis. The investigation, however, has been focused only on ${}^{40}\mathrm{Ca}$.

Purpose: We systematically investigate the existence of exotic torus isomers and their precession motions for a series of $N=Z$ even-even nuclei from ${}^{28}\mathrm{Si}$ to ${}^{56}\mathrm{Ni}$. We analyze the microscopic shell structure of the torus isomer and discuss why the torus shape is generated beyond the limit of large oblate deformation.

Method: We use the cranked three-dimensional Hartree-Fock method with various Skyrme interactions in a systematic search for high-spin torus isomers. We use the three-dimensional time-dependent Hartree-Fock method for describing the precession motion of the torus isomer.

Results: We obtain high-spin torus isomers in ${}^{36}\mathrm{Ar},{}^{40}\mathrm{Ca},{}^{44}\mathrm{Ti},{}^{48}\mathrm{Cr}$, and ${}^{52}\mathrm{Fe}$. The emergence of the torus isomers is associated with the alignments of single-particle angular momenta, which is the same mechanism as found in ${}^{40}\mathrm{Ca}$. It is found that all the obtained torus isomers execute the precession motion at least two rotational periods. The moment of inertia about a perpendicular axis, which characterizes the precession motion, is found to be close to the classical rigid-body value.

Conclusions: The high-spin torus isomer of ${}^{40}\mathrm{Ca}$ is not an exceptional case. Similar torus isomers exist widely in nuclei from ${}^{36}\mathrm{Ar}$ to ${}^{52}\mathrm{Fe}$ and they execute the precession motion. The torus shape is generated beyond the limit of large oblate deformation by eliminating the $0s$ components from all the deformed single-particle wave functions to maximize their mutual overlaps.

Background: In the traditional continuum discretized coupled-channels (CDCC) method, the clusters of the projectile are structureless. Exotic nuclei exhibit unusual properties and often show significant couplings to the continuum. Therefore, reaction models that consider a more accurate structure of the projectile are often preferable. A microscopic description of the projectile, based on an effective nucleon-nucleon (NN) interaction, in a microscopic CDCC (MCDCC) model [Descouvemont and Hussein, Phys. Rev. Lett. 111, 082701 (2013)] has been successfully applied to ${}^7\mathrm{Li}+{}^{208}\mathrm{Pb}$ scattering.

Purpose: The MCDCC method is applied to low-energy elastic scattering of ${}^{17}\mathrm{F},{}^{17}\mathrm{O}$, and ${}^{19}\mathrm{F}$ on ${}^{58}\mathrm{Ni}$ and ${}^{208}\mathrm{Pb}$ targets. The goal of the calculations is twofold: to test the adequacy and the accuracy of the MCDCC model for heavier projectiles and to study the contribution of various channels to the elastic scattering cross sections.

Methods: The elastic scattering cross sections are calculated by using the MCDCC method. The nucleon-target optical potential is folded with the projectile densities resulting from an effective NN interaction, which includes central nuclear, spin-orbit, and Coulomb terms. Discretization of the continuum is achieved via the pseudostate method. Coupled equations are solved by using the $R$-matrix method on a Lagrange mesh.

Results: For the test case of ${}^{17}\mathrm{F}$ at 10 MeV/nucleon, the cross sections are weakly sensitive to the choice of the effective NN interaction. Three different energy-dependent optical nucleon-target potentials provide a similar reasonable agreement with data. Just below the Coulomb barrier, the MCDCC significantly underestimates the cross sections at larger angles. The coupling to the continuum is not significant in most of the assessed cases.

Conclusions: The MCDCC is very satisfactory in the sense that it includes the microscopic properties of the projectile in a reaction model. Well above the Coulomb barrier, the cross sections are in a good agreement with the data. The reasons for the discrepancy between the data and the calculated cross sections at the lower energies, which is also observed in a traditional CDCC, are unclear.

Extensions of the eikonal approximation to low energy (20 MeV/nucleon typically) are studied. The relation between the dynamical eikonal approximation (DEA) and the continuum-discretized coupled-channels method with the eikonal approximation (E-CDCC) is discussed. When Coulomb interaction is artificially turned off, DEA and E-CDCC are shown to give the same breakup cross section, within 3% error, of ${}^{15}\mathrm{C}$ on ${}^{208}\mathrm{Pb}$ at 20 MeV/nucleon. When the Coulomb interaction is included, the difference is appreciable and none of these models agrees with full CDCC calculations. An empirical correction significantly reduces this difference. In addition, E-CDCC has a convergence problem. By including a quantum-mechanical correction to E-CDCC for lower partial waves between ${}^{15}\mathrm{C}$ and ${}^{208}\mathrm{Pb}$, this problem is resolved and the result perfectly reproduces full CDCC calculations at a lower computational cost.

Isotopic ratios for light fragments ($Z\le 4$) emitted by the quasiprojectile (QP) and the mid-rapidity (MR) sources are investigated by the use of a slightly asymmetric system (${}^{36}\mathrm{Ar}+{}^{58}\mathrm{Ni}$) and a symmetric one (${}^{58}\mathrm{Ni}+{}^{58}\mathrm{Ni}$) for six energies between 32A and 84A MeV and three semiperipheral centrality range selections. Experimental data come from the INDRA $4\pi$ multidetector. The results show a clear neutron-rich isotope production from the MR region as compared to the QP source. The beam energy and the centrality also show interesting different trends depending on the charge of the fragments and the emission source. Experimental results are compared to antisymmetrized molecular dynamics simulations.

The pentaquark ${\Theta }^{+}$ has been searched for via the ${\pi }^{-}p\to K^{-}X$ reaction with beam momenta of 1.92 and 2.01 GeV/$c$ at J-PARC. A missing mass resolution of 2 MeV (FWHM) was achieved but no sharp peak structure was observed. The upper limits on the production cross section averaged over the scattering angle from $2^{\circ }$ to ${15}^{\circ }$ in the laboratory frame were found to be less than 0.28 $\mu \mathrm{b}/\mathrm{sr}$ at the 90% confidence level for both the 1.92- and 2.01-GeV/$c$ data. The systematic uncertainty of the upper limits was controlled within 10%. Constraints on the ${\Theta }^{+}$ decay width were also evaluated with a theoretical calculation using an effective Lagrangian. The present result implies that the width should be less than 0.36 and 1.9 MeV for the spin-parity of $1/2^{+}$ and $1/2^{-}$, respectively.

The cross section for one-proton knockout from ${}^{14}\mathrm{O}$ on a carbon target at 305 MeV/nucleon was measured to be ${\sigma }_{-p}({}^{14}\mathrm{O}\to {}^{13}\mathrm{N})=35\left(5\right)\mathrm{mb}$. The one-proton one-neutron ($pn$) removal cross section ${\sigma }_{-p-n}({}^{14}\mathrm{O}\to {}^{12}\mathrm{N})=30\left(6\right)\mathrm{mb}$ and two-proton one-neutron ($2pn$) removal cross section ${\sigma }_{-2p-n}({}^{14}\mathrm{O}\to {}^{11}\mathrm{C})=41\left(6\right)\mathrm{mb}$ were also obtained. The deduced reduction factor, the ratio of the experimental and theoretical cross sections, is close to unity for one-proton knockout from ${}^{14}\mathrm{O}$, consistent with the systematics as well as the result obtained at a much lower beam energy. The indirect reaction process, which involves a one-neutron knockout plus proton(s) evaporation mechanism, is expected to contribute much to the $pn$ and $2pn$ removal.

The asymptotic form of a neutron Cooper pair penetrating to the exterior of a nuclear surface is investigated with the Bogoliubov theory for the superfluid fermions. Based on a two-particle Schrödinger equation governing the Cooper-pair wave function and systematic studies for both weakly bound and stable nuclei, the Cooper pair is shown to be spatially correlated even in the asymptotic large distance limit, and the penetration length of the pair condensate is revealed to be universally governed by the two-neutron separation energy $S_{2n}$ and the di-neutron mass $2m$.