The relativistic point-form formalism that we proposed for the study of the electroweak structure of few-body bound states is applied to calculate the elastic form factors of spin-1 mesons, such as the $\rho$, within constituent-quark models. We treat electron-meson scattering as a Poincaré-invariant coupled-channel problem for a Bakamjian-Thomas mass operator and extract the meson current from the resulting invariant 1-photon-exchange amplitude. Wrong cluster properties inherent in the Bakamjian-Thomas framework are seen to cause spurious contributions in the current. These contributions, however, can be separated unambiguously from the physical ones and we end up with a meson current with all required properties. Numerical results for the $\rho$-meson form factors are presented assuming a simple harmonic-oscillator bound-state wave function. The comparison with other approaches reveals a remarkable agreement of our results with those obtained within the covariant light-front scheme proposed by Carbonell et al. [Phys. Rep. 300, 215 (1998)].

Background: Nuclear density functional theory is the only microscopical theory that can be applied throughout the entire nuclear landscape. Its key ingredient is the energy density functional.

Purpose: In this work, we propose a new parametrization unedf2 of the Skyrme energy density functional.

Methods: The functional optimization is carried out using the pounders optimization algorithm within the framework of the Skyrme Hartree-Fock-Bogoliubov theory. Compared to the previous parametrization unedf1, restrictions on the tensor term of the energy density have been lifted, yielding a very general form of the energy density functional up to second order in derivatives of the one-body density matrix. In order to impose constraints on all the parameters of the functional, selected data on single-particle splittings in spherical doubly-magic nuclei have been included into the experimental dataset.

Results: The agreement with both bulk and spectroscopic nuclear properties achieved by the resulting unedf2 parametrization is comparable with unedf1. While there is a small improvement on single-particle spectra and binding energies of closed shell nuclei, the reproduction of fission barriers and fission isomer excitation energies has degraded. As compared to previous unedf parametrizations, the parameter confidence interval for unedf2 is narrower. In particular, our results overlap well with those obtained in previous systematic studies of the spin-orbit and tensor terms.

Conclusions: unedf2 can be viewed as an all-around Skyrme EDF that performs reasonably well for both global nuclear properties and shell structure. However, after adding new data aiming to better constrain the nuclear functional, its quality has improved only marginally. These results suggest that the standard Skyrme energy density has reached its limits, and significant changes to the form of the functional are needed.

Total fission cross sections of ${}^{181}$Ta induced by protons at different relativistic energies have been measured at GSI Darmstadt using the inverse kinematic technique. These data contribute to solve inconsistencies in previously reported measurements, but also help to benchmark state-of-the-art reaction codes. The energy range covered with these measurements allowed us to investigate the onset and temperature dependence of dissipative and transient effects at small deformation.

Measurements of mesons containing charm or bottom quarks at high transverse momentum ($P_T$) constitute an interesting set of probes for the nature of the interaction of hard partons with a QCD medium, as created in ultrarelativistic heavy-ion ($A$-$A$) collisions. Not only can $D$ and $B$ mesons to a reasonable accuracy be assumed to represent the hadronization of a $b$ or $c$ quark after passage through the medium (i.e., they explicitly reflect quark-medium interaction), but also their interaction physics is expected to be different from that of light partons traversing a medium: The quark mass restricts radiation phase space, leading to a reduction of both vacuum and medium-induced radiation, a phenomenon known as the “dead cone effect.” Owing to this difference in physics, heavy quark interaction with the medium is usually treated in the leading parton energy-loss approximation, whereas the theory of light parton physics has moved to modeling the full medium-modified shower evolution. In this work, an attempt is made to create a more unified description of light parton and heavy quark physics at high $P_T$ by computing charm-medium interactions in terms of the nuclear suppression factor and back-to-back correlations using an in-medium shower evolution Monte Carlo code that is well tested for light parton physics and thus to verify whether the charm quark mass is sufficiently small compared to $P_T$ to allow an in-medium shower computation consistent with light partons, i.e., without changing or introducing new parameters.

The interaction mechanism of the $\Sigma$(1385) photoproduction from proton $\gamma p\to K^{+}{\Sigma }^0\left(1385\right)$ is investigated within a Regge-plus-resonance approach based on the experimental data released by the CLAS Collaboration recently. The $t$ channel and the $u$ channel are responsible for the behaviors of differential cross sections at forward and backward angles, respectively. The contributions from nucleon resonances including $N^{*}$ and ${\Delta }^{*}$, which are determined by the predicted decay amplitudes in the constituent quark model, are found to be small, but the $F_{35}$ state $\Delta \left(2000\right)$ is essential to reproduce the differential cross section.

We report our analysis of $d_{\mathrm{like}}/p_{\mathrm{like}}$ ratio and entropy production in heavy-ion collisions using an isospin-dependent quantum molecular dynamics model. The entropy is estimated using the method proposed by Siemens and Kapusta [P. J. Siemens and J. I. Kapusta, Phys. Rev. Lett. 43, 1486 (1979)]. Our calculations are in good agreement with experimental data. We also study the role of the neutron content of colliding pairs on the production of $d_{\mathrm{like}}/p_{\mathrm{like}}$ ratio and entropy. Our findings reveal that entropy decreases with an increase in the isospin asymmetry for both isotopic and isobaric pairs.

The positive-parity excited states of ${}^{56}\mathrm{Ni}$ and instability of the $N=Z=28$ shell gap are discussed on the basis of the antisymmetrized molecular dynamics calculation using the Gogny D1S effective interaction. It is found that ${}^{56}\mathrm{Ni}$ is quite soft against oblate deformation and the $N=Z=28$ closed-shell configuration amounts to only $62\%$ in the ground state. It is also found that the shell gap easily disappears by prolate deformation, which leads to the coexistence of the almost spherical ground band, excited $\beta$ and $\gamma$ bands, and a prolate superdeformed band with ${\left(f_{7/2}\right)}^{-m}{\left(p_{3/2}\right)}^m$ configurations within the small excitation energies. Furthermore, in the highly excited region, it is predicted that a couple of strongly deformed bands with ${\left(sd\right)}^{-m}{\left(pf\right)}^{-n}{\left(g_{9/2}\right)}^{m+n}$ configurations are built on the $0^{+}$ states around 20 MeV.

Strictly finite-range (SFR) potentials are exactly zero beyond their finite range. Single-particle energies and densities, as well as $S$-matrix pole trajectories, are studied in a few SFR potentials suited for the description of neutrons interacting with light and heavy nuclei. The SFR potentials considered are the standard cutoff Woods-Saxon (CWS) potentials and two potentials approaching zero smoothly: the SV potential introduced by Salamon and Vertse [Phys. Rev. C 77, 037302 (2008)] and the SS potential of Sahu and Sahu [Int. J. Mod. Phys. E 21, 1250067 (2012)]. The parameters of these latter potentials were set so that the potentials may be similar to the CWS shape. The range of the SV and SS potentials scales with the cube root of the mass number of the core like the nuclear radius itself. For light nuclei a single term of the SV potential (with a single parameter) is enough for a good description of the neutron-nucleus interaction. The trajectories are compared with a benchmark for which the starting points (belonging to potential depth zero) can be determined independently. Even the CWS potential is found to conform to this benchmark if the range is identified with the cutoff radius. For the CWS potentials some trajectories show irregular shapes, while for the SV and SS potentials all trajectories behave regularly.

Hadron resonance gas models provide a good description of the equation of state of quantum chromodynamics determined by lattice QCD calculations at temperatures $T\sim 100–155$ MeV. In this paper we investigate the effects of an exponentially increasing hadron mass spectrum (Hagedorn spectrum) on the azimuthal anisotropy of the rapidly expanding matter formed in ultrarelativistic heavy-ion collisions. If the temperature at which the conversion from fluid degrees of freedom to hadrons is sufficiently close to the Hagedorn temperature, the production of Hagedorn resonances suppresses the differential elliptic flow of all hadron species.

The influence of inelastic excitations on heavy-ion fusion is well established and can be quantitativly described by coupled-channels calculations. The influence of transfer channels, however, is still under debate. We have analyzed a large set of heavy-ion-induced fusion excitation functions involving nuclei with similar structures and show that there is a universal correlation between the shape (and enhancement) of the excitation function and the strength of the total neutron-transfer cross sections for systems ranging from light to heavy masses.

We present measurements of $n$-$d$ analyzing power, $A_y\left(\theta \right)$, at $E_n=22.5$ MeV. The experiment uses a shielded neutron source which produced polarized neutrons via the ${}^2$H($\vec{d}$,$\vec{n}$)${}^3$He reaction. It also uses a deuterated liquid-scintillator center detector and six pairs of liquid-scintillator neutron side detectors. Elastic neutron scattering events are identified by using time-of-flight techniques and by setting a window in the center detector pulse-height spectrum. The beam polarization is monitored by using a high-pressure helium gas cell and an additional pair of liquid-scintillator side detectors. The $n$-$d$ $A_y\left(\theta \right)$ data were corrected for finite-geometry and multiple-scattering effects using a Monte Carlo simulation of the experiment. The 22.5-MeV data demonstrate that the three-nucleon analyzing power puzzle also exists at this energy. They show a significant discrepancy with predictions of high-precision nucleon-nucleon potentials alone or combined with Tucscon-Melbourne or Urbana IX three-nucleon forces, as well as currently available effective-field theory based potentials of next-to-next-to-next-to-leading order.

The low-lying spectra including the first few excited positive and negative parity bands of some heavy even-even nuclei from the rare earth and actinide mass regions are investigated within the framework of the symplectic interacting vector boson model with the Sp(12,$R$) dynamical symmetry group. Symplectic dynamical symmetries allow the change of the number of excitation quanta or phonons building the collective states, providing for larger representation spaces and richer subalgebraic structures to incorporate more complex nuclear spectra. The theoretical predictions for the energy levels and the electromagnetic transitions between the collective states of the ground-state band and $K^{\pi }=0^{-}$ band are compared with experiment and some other collective models incorporating octupole and/or dipole degrees of freedom. The energy staggering, which is a sensitive indicator of the octupole correlations in even-even nuclei, is also calculated and compared with experiment. The results obtained for the energy levels, energy staggering, and transition strengths reveal the relevance of the dynamical symmetry used in the model to simultaneously describe both positive and negative parity low-lying collective bands.

Decay properties of the neutron-deficient nuclides ${}^{201–203}\mathrm{Ra}$ and ${}^{200–202}\mathrm{Fr}$ were investigated using $\alpha$- and $\gamma$-decay spectroscopy. The nuclei were produced in fusion-evaporation reactions of ${}^{56}$Fe projectiles with enriched ${}^{147}$Sm and ${}^{149}$Sm targets at the velocity filter SHIP at GSI in Darmstadt (Germany). The $\alpha$ decay from the (3/2${}^{-}$) state in ${}^{201}$Ra was identified with an energy $E_{\alpha }=7842\left(12\right)$ keV and half-life $T_{1/2}=8_{-4}^{+40}$ ms. Ambiguous decay properties for ${}^{202}$Ra from previous measurements were clarified by remeasuring with significantly improved precision, resulting in values of $E_{\alpha }=7722\left(7\right)$ keV and $T_{1/2}=3.8_{-0.8}^{+1.3}$ ms. New short-lived isomeric states were identified in ${}^{200}$Fr and ${}^{201}$Fr with half-lives of 0.6${}_{-0.2}^{+0.5}$ $\mu$s and 0.7${}_{-0.2}^{+0.5}$ $\mu$s, respectively. A tentative spin and parity of 13/2${}^{+}$ were assigned to the latter. One event attributed to $\beta$-delayed fission of ${}^{200}$Fr was observed.

The complete-experiment problem in the truncated partial-wave analysis (PWA) of pseudoscalar meson photoproduction with suppressed $t$-channel exchanges is investigated. The focus is set to ambiguities of the group S observables with the unpolarized differential cross section, ${\sigma }_0$, and the three single-spin observables, $\Sigma$, $T$, and $P$. For this purpose, the approach and formalism already worked out by Omelaenko [Sov. J. Nucl. Phys. 34, 406 (1981)] is revisited in this work. A numerical study using multipoles of the PWA solution MAID2007 shows how only one additional double polarization observable can resolve all ambiguities. Therefore, the possibility emerges to perform a complete experiment with only five observables.

The isobaric yield ratio difference between two reactions is found to equal $\Delta {\mu }_{21}/T$, which denotes the ratio of the difference between the neutron and proton chemical potentials to the temperature. A series of projectile fragmentation reactions induced by calcium isotopes are calculated using a modified statistical abrasion-ablation model, assuming the neutron density distribution to be the Fermi type. The $\Delta {\mu }_{21}/T$ from the prefragments are found to be sensitive to the difference between the neutron density distributions of projectiles, while $\Delta {\mu }_{21}/T$ from the final fragments are very similar for the reactions and insensitive to the difference between the neutron density distributions of projectiles. The $\Delta {\mu }_{21}/T$ from the prefragments and final fragments verify that the deexcitation modifies the results largely.

Low-energy multinucleon transfer reactions are shown to comprise a very effective tool for the production and spectroscopic study of light exotic nuclei. The corresponding cross sections are found to be significantly larger as compared with high-energy fragmentation reactions. Several optimal reactions for the production of extremely neutron-rich isotopes of elements with $Z=6–14$ are proposed.

Derivations of relativistic second-order dissipative hydrodynamic equations have relied almost exclusively on the use of Grad's 14-moment approximation to write $f(x,p)$, the nonequilibrium distribution function in the phase space. Here we consider an alternative Chapman-Enskog-like method, which, unlike Grad's, involves a small expansion parameter. We derive an expression for $f(x,p)$ to second order in this parameter. We show analytically that while Grad's method leads to the violation of the experimentally observed $1/\sqrt{m_T}$ scaling of the longitudinal femtoscopic radii, the alternative method does not exhibit such an unphysical behavior. We compare numerical results for hadron transverse-momentum spectra and femtoscopic radii obtained in these two methods, within the one-dimensional scaling expansion scenario. Moreover, we demonstrate a rapid convergence of the Chapman-Enskog-like expansion up to second order. This leads to an expression for $\delta f(x,p)$ which provides a better alternative to Grad's approximation for hydrodynamic modeling of relativistic heavy-ion collisions.