We investigate the effect of the global charge conservation on the cumulants of conserved charges observed in relativistic heavy ion collisions in a finite rapidity window, $\Delta \eta$, with a special emphasis on the time evolution of fluctuations in the hadronic medium. It is argued that the experimental result of the net-electric-charge fluctuation observed by the ALICE Collaboration does not receive effects from global charge conservation because of the finite diffusion distance of charged particles in the hadronic stage. We emphasize that the magnitude of the effect of global charge conservation can be estimated experimentally by combining the information on the $\Delta \eta$ dependencies of various cumulants of conserved charges, similarly to other dynamical properties of the hot medium.

Recent studies have shown that fluctuations of various types play important roles in the evo lution of the fireball created in relativistic heavy-ion collisions and bear many phenomenological consequences for experimental observables. The bulk dynamics of the fireball is well described by relativistic hydrodynamic expansion and the fluctuations on top of such expanding background can be studied within the linearized hydrodynamic framework. In this paper we present complete and analytic sound-wave solutions on top of both Bjorken flow and Hubble flow backgrounds.

We report the results of a calculation of the nuclear matrix element of neutrinoless double-$\beta$ decay of ${}^{48}\mathrm{Ca}$, carried out taking into account nucleon-nucleon correlations in both coordinate and spin space. Our numerical results, obtained using nuclear matter correlation functions, suggest that inclusion of correlations may lead to a $\sim 20$% decrease of the matrix element, with respect to the shell-model prediction. This conclusion is supported by the results of an independent calculation, in which correlation effects are taken into account using the spectroscopic factors of ${}^{48}\mathrm{Ca}$, obtained from an ab initio many-body approach, to renormalize the shell-model states.

We discuss the formation of $\Delta$ isobars in neutron star matter. We show that their threshold density strictly correlates with the density derivative of the symmetry energy of nuclear matter: the $L$ parameter. By restricting $L$ to the range of values indicated by recent experimental and theoretical analysis, i.e., $40\text{MeV}\lesssim L\lesssim 62\text{MeV}$, we find that $\Delta$ isobars appear at a density of the order of 2 to 3 times the nuclear matter saturation density, i.e., the same range as for the appearance of hyperons. The range of values of the couplings of the $\Delta \mathrm{s}$ with the mesons is restricted by the analysis of the data obtained from photoabsorption, electron and pion scattering on nuclei. If the potential of the $\Delta$ in nuclear matter is close to the one indicated by the experimental data then the equation of state becomes soft enough that a “Δ puzzle” exists, similar to the “hyperon puzzle” widely discussed in the literature. Possible solutions to this puzzle are also discussed.

We combine the coupled-cluster method and the Lorentz integral transform for the computation of inelastic reactions into the continuum. We show that the bound-state-like equation characterizing the Lorentz integral transform method can be reformulated based on extensions of the coupled-cluster equation-of-motion method, and we discuss strategies for viable numerical solutions. Starting from a chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order, we compute the giant dipole resonances of ${}^4\mathrm{He}$, ${}^{16,22}\mathrm{O}$, and ${}^{40}\mathrm{Ca}$, truncating the coupled-cluster equation-of-motion method at the two-particle–two-hole excitation level. Within this scheme, we find a low-lying $E1$ strength in the neutron-rich ${}^{22}\mathrm{O}$ nucleus, which compares fairly well with data from Leistenschneider et al. [Phys. Rev. Lett. 86, 5442 (2001)]. We also compute the electric dipole polarizability in ${}^{40}\mathrm{Ca}$. Deficiencies of the employed Hamiltonian lead to overbinding, too-small charge radii, and a too-small electric dipole polarizability in ${}^{40}\mathrm{Ca}$.

Background: Detailed studies on the effect of the breakup of weakly bound projectile on fission are scarce. Distinguishing the events of compound nuclear (CN) fission from the breakup or transfer induced fission to understand the properties of measured fission fragments is difficult but desirable.

Purpose: To investigate the effect of projectile breakup and its breakup threshold energy on fission-fragment (FF) mass distributions and folding angle distributions for ${}^{6,7}\mathrm{Li} + {}^{238}\mathrm{U}$ reactions and find out the differences in the properties of the fission events produced by complete fusion (CF) from the total fusion (TF).

Methods: The FF mass and folding angle distributions have been measured at energies around the Coulomb barrier using gas detectors by time-of-flight technique. The results are compared with the ones involving tightly bound projectiles as well as predictions from systematics to bring out the effect of the breakup.

Results: A sharp increase in the peak to valley (P:V) ratio of FF mass distribution with the decrease in bombarding energy for ${}^{6,7}\mathrm{Li} + {}^{238}\mathrm{U}$ reactions is observed when all events are assumed to be CN fission. As the beam energy falls through the fusion barrier, the full width half maximum (FWHM) of the FF folding angle distribution is found to increase at sub-barrier energies, unlike the reactions involving tightly bound projectiles where a linear decrease in FWHM is expected. By selecting pure CN events from the scatter plot of the velocity components of the composite nuclei, the energy dependence of the deduced FWHM is found to be consistent with the ones involving tightly bound projectiles. Similarly, the P:V ratio obtained for the selected CN events is consistent with the theoretical calculations as well as the experimental data for the proton induced reaction forming similar CN.

Conclusions: The presence of projectile breakup induced fission and a relatively low breakup threshold for ${}^6\mathrm{Li}$ compared to ${}^7\mathrm{Li}$ explains the observed differences in the energy dependence of the P:V ratio and the FWHM of FF folding angle distributions for CF and TF fission in the present reactions.

The ${}^9\mathrm{Be}\left({}^{18}\mathrm{O},{}^{17}\mathrm{O}\right){}^{10}\mathrm{Be}$ reaction has been studied at an incident energy of 84 MeV, and the ejectiles have been detected at forward angles. The ${}^{10}\mathrm{Be}$ excitation energy spectrum has been obtained up to about 18 MeV, and several known bound and resonant states of ${}^{10}\mathrm{Be}$ have been identified. Calculations that describe the interaction of the neutron removed from the ${}^{18}\mathrm{O}$ projectile with the ${}^9\mathrm{Be}$ target by means of an optical potential with a semiclassical approximation for the relative motion account for a significant part of the ${}^{10}\mathrm{Be}$ continuum. Two parametrizations of the optical-model potential for the system $n\text{−}{}^9\mathrm{Be}$ have been used and compared.

Excited states in ${}^{113}\mathrm{Pd}$, populated in ${\beta }^{-}$ decay of ${}^{113}\mathrm{Rh}$ and in spontaneous fission of ${}^{248}\mathrm{Cm}$ and ${}^{252}\mathrm{Cf}$, have been studied by means of $\gamma$ spectroscopy at the IGISOL facility of Jyväskylä University and using large arrays of Ge detectors (Eurogam2 and Gammasphere, respectively). The position of the ${\mathrm{11/2}}^{-}$ yrast excitation in ${}^{113}\mathrm{Pd}$, proposed recently at 166.1 keV by other authors, has been corrected to 98.9 keV. The decay of this level has been discussed to explain the observed transition intensities. The ${\mathrm{7/2}}^{-}$ member of the yrast, unique-parity configuration has been identified at 84.9 keV and a band on top of this level proposed. On top of the 1/2+, first excited state a band has been built and a new 3/2+ bandhead has been proposed at 151.9 keV. A possible oblate-shape origin of these low-energy bandsheads has been discussed.

The lightest baryon octet is studied within a covariant and confining Nambu–Jona-Lasinio model. By solving the Poincaré covariant Faddeev equations—including scalar and axialvector diquarks—we determine the baryon octet masses and axial charges for strangeness conserving transitions. For the axial charges the degree of violation of SU(3) flavor symmetry, arising because of the strange spectator quark(s), is found to be no more than 10%.

Nuclear structure observables usually most effectively probe the properties of nuclear matter at subsaturation densities rather than at saturation density. We demonstrate that the electric dipole polarizibility ${\alpha }_{\text{D}}$ in ${}^{208}\mathrm{Pb}$ is sensitive to both the magnitude $E_{\text{sym}}\left({\rho }_{\text{c}}\right)$ and density slope $L\left({\rho }_{\text{c}}\right)$ of the symmetry energy at the subsaturation cross density ${\rho }_{\text{c}}=0.11$ ${\mathrm{fm}}^{-3}$. Using the experimental data of ${\alpha }_{\text{D}}$ in ${}^{208}\mathrm{Pb}$ from RCNP (Research Center for Nuclear Physics, Osaka University) and the recent accurate constraint of $E_{\text{sym}}\left({\rho }_{\text{c}}\right)$ from the binding energy difference of heavy isotope pairs, we extract a value of $L\left({\rho }_{\text{c}}\right)=47.3\pm 7.8$ MeV. The implication of the present constraint of $L\left({\rho }_{\text{c}}\right)$ to the symmetry energy at saturation density, the neutron skin thickness of ${}^{208}\mathrm{Pb}$ and the core-crust transition density in neutron stars is discussed.

Based on the boson realization of the Euclidean algebras, it is shown that the five-dimensional Euclidean dynamical symmetry may emerge at the triple point of the shape phase diagram of the interacting boson model, which thus offers a symmetry-based understanding of this isolated point. It is further shown that the low-lying dynamics in ${}^{108}\mathrm{Pd}$, ${}^{134}\mathrm{Ba}$, ${}^{64}\mathrm{Zn}$, and ${}^{114}\mathrm{Cd}$ may be dominated by the Euclidean dynamical symmetry.

Fusion reactions of ${}^{16}\mathrm{O}+{}^{16}\mathrm{O},{}^{40}\mathrm{Ca}+{}^{40}\mathrm{Ca}$, and ${}^{40}\mathrm{Ca}+{}^{90}\mathrm{Zr}$ have been investigated by using the three-dimensional (3D) time-dependent Hartree-Fock approach with and without density constraint. The interaction potentials and effective mass parameters are studied. It is found that both the nucleus-nucleus interaction potentials and the effective mass parameters of these systems depend on the impact parameter. Such noncentral effects on fusion cross sections are also investigated. It is shown that the noncentral effect can reduce the fusion cross sections significantly when the incident energy is just above the barrier, while it becomes weaker with the increasing incident energy and can be totally neglected when the energy is up to twice as much as the barrier height in these spherical colliding systems.

We explore the electromagnetic contribution to the charge symmetry breaking in the octet baryon masses using a subtracted dispersion relation based on the Cottingham formula. For the proton-neutron mass splitting we report a minor revision of the recent analysis of Walker-Loud, Carlson, and Miller [Phys. Rev. Lett. 108, 232301 (2012)]. For the electromagnetic structure of the hyperons we constrain our analysis, where possible, by a combination of lattice QCD and SU(3) symmetry-breaking estimates. The results for the baryon mass splittings are found to be compatible with recent lattice $\mathrm{QCD}+\mathrm{QED}$ determinations. The uncertainties in the dispersive analysis are dominated by the lack of knowledge of the hyperon inelastic structure.

Background: Collective inertia is strongly influenced at the level crossing at which the quantum system changes its microscopic configuration diabatically. Pairing correlations tend to make the large-amplitude nuclear collective motion more adiabatic by reducing the effect of these configuration changes. Competition between pairing and level crossing is thus expected to have a profound impact on spontaneous fission lifetimes.

Purpose: To elucidate the role of nucleonic pairing on spontaneous fission, we study the dynamic fission trajectories of ${}^{264}\mathrm{Fm}$ and ${}^{240}\mathrm{Pu}$ using the state-of-the-art self-consistent framework.

Methods: We employ the superfluid nuclear density functional theory with the Skyrme energy density functional ${\mathrm{SkM}}^{*}$ and a density-dependent pairing interaction. Along with shape variables, proton and neutron pairing correlations are taken as collective coordinates. The collective inertia tensor is calculated within the nonperturbative cranking approximation. The fission paths are obtained by using the least action principle in a four-dimensional collective space of shape and pairing coordinates.

Results: Pairing correlations are enhanced along the minimum-action fission path. For the symmetric fission of ${}^{264}\mathrm{Fm}$, where the effect of triaxiality on the fission barrier is large, the geometry of the fission pathway in the space of the shape degrees of freedom is weakly impacted by pairing. This is not the case for ${}^{240}\mathrm{Pu}$, where pairing fluctuations restore the axial symmetry of the dynamic fission trajectory.

Conclusions: The minimum-action fission path is strongly impacted by nucleonic pairing. In some cases, the dynamical coupling between shape and pairing degrees of freedom can lead to a dramatic departure from the static picture. Consequently, in the dynamical description of nuclear fission, particle-particle correlations should be considered on the same footing as those associated with shape degrees of freedom.

Employing a recently developed dispersive optical model (DOM) which allows a complete description of experimental data both above (up to 200 MeV) and below the Fermi energy in ${}^{40}\mathrm{Ca}$, we demonstrate that elastic nucleon-nucleus scattering data constrain the spectral strength in the continuum of orbits that are nominally bound in the independent-particle model (IPM). In the energy domain between 0 and 200 MeV, the integrated strength or depletion number is highly sensitive to the separation of the IPM orbit to the scattering continuum. This sensitivity is determined by the influence of the surface-absorption properties of the DOM self-energy. For an ab initio calculation employing the self-energy of the charge-dependent Bonn (CDBonn) interaction which only includes the effect of short-range correlations, no such sensitivity is obtained and a depletion of 4% is predicted between 0 and 200 MeV irrespective of the orbit. The ab initio spectral strength generated with the CDBonn interaction approaches the empirical DOM spectral strength at 200 MeV. Both spectral distributions allow for an additional 3–5% of the strength at even higher energies which is associated with the influence of short-range correlations. We suggest that the nonlocal form of the DOM allows for an analysis of elastic-nucleon-scattering data that directly determines the depletion of bound orbits. While obviously relevant for the analysis of elastic nucleon scattering on stable targets, this conclusion holds equally well for experiments involving rare isotopes in inverse kinematics as well as experiments with electrons on atoms or molecules.

The first $0^{+}$ resonant state of the ${}^{12}\mathrm{C}$ nucleus, ${}^{12}\mathrm{C}\left(0_2^{+}\right)$, the so-called Hoyle state, is investigated in a three-$\alpha$-particle (3-$\alpha$) model. A wave function for the photodisintegration reaction of a ${}^{12}\mathrm{C}$ bound state to 3-$\alpha$ final states is defined and calculated by the Faddeev three-body formalism, in which three-body bound and continuum states are treated consistently. From the wave function at the Hoyle state energy, I calculated distributions of outgoing $\alpha$ particles and density distributions at interior region of the Hoyle state. Results show that a process through a two-$\alpha$ resonant state is dominant in the decay and contributions of the rest process are very small, less than 1%. There appear to be some peaks in the interior density distribution corresponding to configurations of equilateral and isosceles triangles. It turns out that these results are obtained independently of the choice of $\alpha$-particle interaction models, when they are made to reproduce the Hoyle state energy.

Photoneutron cross sections were measured for the seven stable samarium isotopes ${}^{144,147,148,149,150,152,154}\mathrm{Sm}$ near the neutron threshold with quasi-monochromatic laser-Compton scattering $\gamma \mathrm{rays}$. Our photoneutron cross sections are found to be low by 20%–37% relative to existing data. The photoneutron data are analyzed with the talys reaction code by considering the Skyrme Hartree-Fock-Bogoliubov (HFB) plus quasiparticle random phase approximation (QRPA) model and the axially symmetric deformed Gogny HFB plus QRPA model of the $E1$ $\gamma \text{−}\mathrm{ray}$ strength. Using the $\gamma \text{−}\mathrm{ray}$ strength function constrained by the present photoneutron data, we made a thorough analysis of the reverse $(n,\gamma )$ cross sections including the radioactive nucleus ${}^{151}\mathrm{Sm}$ with a half-life of 90 yr. The radiative neutron capture cross section for ${}^{153}\mathrm{Sm}$ with the half-life of 1.928 d is deduced with the $\gamma \text{−}\mathrm{ray}$ strength function method.

Inelastic ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ rainbow scattering to the $2^{+}$ (4.44 MeV) state of ${}^{12}\mathrm{C}$ was measured at the incident energies, $E_L$ = 170, 181, 200, 260, and 281 MeV. A systematic analysis of the experimental angular distributions was performed using the coupled-channels method with an extended double folding potential derived from realistic wave functions for ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ calculated with a microscopic $\alpha$ cluster model and a finite-range density-dependent nucleon-nucleon force. The coupled-channels analysis of the measured inelastic-scattering data shows consistently some Airy-like structure in the inelastic-scattering cross sections for the first $2^{+}$ state of ${}^{12}\mathrm{C}$, which is somewhat obscured and still not clearly visible in the measured data. The Airy minimum was identified from the analysis and the systematic energy evolution of the Airy structure was studied. The Airy minimum in inelastic scattering is found to be shifted backward compared with that in elastic scattering.

Background: Uncertainties in adopted models of $\text{particle}+\text{nucleu}\mathrm{s}$ optical-model potentials directly influence the accuracy in the theoretical predictions of reaction rates as they are needed for reaction-network calculations in, for instance, $\gamma$-process nucleosynthesis. The improvement of the $\alpha +\text{nucleu}\mathrm{s}$ optical-model potential is hampered by the lack of experimental data at astrophysically relevant energies especially for heavier nuclei.

Purpose: Measuring the ${}^{187}\mathrm{Re}(\alpha ,n){}^{190}\mathrm{Ir}$ reaction cross section at sub-Coulomb energies extends the scarce experimental data available in this mass region and helps understanding the energy dependence of the imaginary part of the $\alpha +\text{nucleus}$ optical-model potential at low energies.

Method: Applying the activation method, after the irradiation of natural rhenium targets with $\alpha$-particle energies of 12.4 to 14.1 MeV, the reaction yield and thus the reaction cross section were determined via $\gamma$-ray spectroscopy by using the Cologne Clover Counting Setup and the method of $\gamma \gamma$ coincidences.

Results: Cross-section values at five energies close to the astrophysically relevant energy region were measured. Statistical model calculations revealed discrepancies between the experimental values and predictions based on widely used $\alpha$+nucleus optical-model potentials. However, an excellent reproduction of the measured cross-section values could be achieved from calculations based on the so-called Sauerwein–Rauscher $\alpha +\text{nucleus}$ optical-model potential.

Conclusion: The results obtained indicate that the energy dependence of the imaginary part of the $\alpha +\text{nucleus}$ optical-model potential can be described by an exponential decrease. Successful reproductions of measured cross sections at low energies for $\alpha$-induced reactions in the mass range $141\le A\le 187$ confirm the global character of the Sauerwein–Rauscher potential.