The quark-meson-coupling (QMC) model has been applied to the study of the properties of even-even superheavy nuclei with $96\le Z\le 110$, over a wide range of neutron numbers. The aim is to identify the deformed shell gaps at $N=152$ and $N=162$, predicted in macroscopic-microscopic (macro-micro) models, in a model based on the mean-field $\text{Hartree-Fock}+\text{BCS}$ approximation. The predictive power of the model has been tested on proton and neutron spherical shell gaps in light doubly closed (sub)shell nuclei ${}^{40}\mathrm{Ca}, {}^{48}\mathrm{Ca}, {}^{56}\mathrm{Ni}, {}^{56}\mathrm{Ni}, {}^{78}\mathrm{Ni}, {}^{90}\mathrm{Zr}, {}^{100}\mathrm{Sn}, {}^{132}\mathrm{Sn}, {}^{146}\mathrm{Gd}$, and ${}^{208}\mathrm{Pb}$, with results in a full agreement with experiment. In the superheavy region, the ground-state binding energies of $98\le Z\le 110$ and $146\le N\le 160$ differ, in the majority of cases, from the measured values by less than $\pm 2.5\mathrm{MeV}$, with the deviation decreasing with increasing $Z$ and $N$. The axial quadrupole deformation parameter, ${\beta }_2$, calculated over the range of neutron numbers $138\le N\le 184$, revealed a prolate-oblate coexistence and shape transition around $N=168$, followed by an oblate-spherical transition towards the expected $N=184$ shell closure in Cm, Cf, Fm, and No. The closure is not predicted in Rf, Sg, Hs, and Ds as another shape transition to a highly deformed (${\beta }_2\approx 0.4$) shape in Sg, Hs, and Ds for $N>178$ appears, while ${}^{288}\mathrm{Rf}$ ($N=184$) remains oblate. The bulk properties predicted by QMC, such as ground-state binding energy, two-neutron separation energy, the empirical shell-gap parameter ${\delta }_{2\mathrm{n}}$ and $Q_{\alpha }$ values, are found to have a limited sensitivity to the deformed shell gaps at $N=152$ and 162. However, the evolution of the neutron single-particle spectra with $0\le {\beta }_2\le 0.55$ of ${}^{244}\mathrm{Cm}, {}^{248}\mathrm{Cf}, {}^{252}\mathrm{Fm}, {}^{256}\mathrm{No}, {}^{260}\mathrm{Rf}, {}^{264}\mathrm{Sg}, {}^{268}\mathrm{Hs}$, and ${}^{272}\mathrm{Ds}$, as representative examples, gives a (model-dependent) evidence for the location and size of the $N=152$ and 162 gaps as a function of $Z$ and $N$. In addition, the neutron number dependence of neutron pairing energies provides supporting indication for existence of the energy gaps. Based on these results, the mean-field QMC and macro-micro models and their predictions of deformed shell structure of superheavy nuclei are compared. Clearly the QMC model does not give results as close to the experiment as the macro-micro models. However, considering that it has only four global variable parameters (plus two parameters of the pairing potential), with no local adjustments, the results are promising.

Background: The proton-induced $\alpha$ knockout reaction has been utilized for decades to investigate the $\alpha$ cluster formation in the ground state of nucleus. However, even today, the theoretical description of the reaction is not precise enough for the quantitative study. For example, the $\alpha$ spectroscopic factors reduced from $\alpha$ knockout experiments with reaction analyses using phenomenological $\alpha$ cluster wave functions disagree with those given by a structure theory. In some cases they also scatter depending on the kinematical condition of the experiment. This suggests that the theoretical description of the $\alpha$ knockout reaction is insufficient from a quantitative viewpoint.

Purpose: We show that the distorted wave impulse approximation can describe ${}^{20}\mathrm{Ne}(p,p\alpha ){}^{16}\mathrm{O}$ reaction quantitatively if reliable inputs are used; the optical potential, the $p-\alpha$ cross section, and the $\alpha$ cluster wave function. We also investigate the relationship between the $\alpha$ cluster wave function and the $\alpha$ knockout cross section.

Method: The ${}^{20}\mathrm{Ne}(p,p\alpha ){}^{16}\mathrm{O}$ reaction is described by the distorted wave impulse approximation. An input of the calculation, the $\alpha -{}^{16}\mathrm{O}$ cluster wave function, is obtained by the antisymmetrized molecular dynamics and the Laplace expansion method.

Results: In contrast to the previous work, the ${}^{20}\mathrm{Ne}(p,p\alpha ){}^{16}\mathrm{O}$ data at 101.5 MeV is successfully reproduced by the present framework without any free adjustable parameters. It is also found that the knockout cross section is sensitive to the surface region of the cluster wave function because of the peripherality of the reaction.

Conclusions: Using a reliable $\alpha$ cluster wave function, $p-\alpha$ cross section, and distorting potentials, it is found that the ${}^{20}\mathrm{Ne}(p,p\alpha ){}^{16}\mathrm{O}$ cross section is quantitatively reproduced by the present framework. This success demonstrates that the proton-induced $\alpha$ knockout reaction is a quantitative probe for the $\alpha$ clustering.

Precise quasielastic experimental excitation function for the ${}^{18}\mathrm{O}+{}^{65}\mathrm{Cu}$ system has been measured and its barrier distribution has been derived. Several reaction channels have been observed on the experimental spectra, revealing the presence of two-neutron and $\alpha$-stripping processes, as well as the proton pickup transfer, for which excitation functions were also measured. Extensive coupled channel and coupled reaction channel calculations have been performed to describe the experimental data. The inelastic couplings of target and projectile, and the ground state reorientation of the target, were important to the proper description of data. The transfer data were well described by calculations; however, it was shown that they almost do not affect the excitation function of ${}^{18}\mathrm{O}+{}^{65}\mathrm{Cu}$ quasielastic scattering. Whenever possible, structure shell model calculations have been performed to obtain the spectroscopic amplitudes of projectile and target overlaps. The two-neutron and $\alpha$-transfer reactions have been calculated considering the transferred particle as a cluster with spin 0.

The weakly bound nature of the deuteron brings the complexity of deuteron-induced reactions compared to nucleon-induced ones and is expected to affect various physical quantities observed in deuteron-induced reactions. Aiming to deep understanding and accurate prediction for the emission of light composite particle (LCP) in deuteron-induced reactions, we revise the computational system dedicated to deuteron-induced reactions, called DEURACS. The model by Iwamoto and Harada describing pre-equilibrium cluster emission which was successfully applied to LCP emission in nucleon-induced reactions is integrated into the framework of DEURACS, in which the breakup processes of incident deuteron are explicitly taken into account. The phenomenological model by Kalbach is also adopted to estimate the contribution from the direct pickup process. Using the revised DEURACS, we analyze the $(d,xt), (d,x{}^3\mathrm{He})$, and $(d,x\alpha )$ reactions in the target mass range $27\le A\le 90$. Regardless of the targets, the calculation results successfully reproduced the experimental data for each reaction, simultaneously. These results demonstrate that the LCP emission from the pre-equilibrium and compound nucleus processes in deuteron-induced reactions, which occupies a large part of the total LCP emission, can be described by the same theoretical models as used in nucleon-induced reactions when the breakup processes of incident deuteron are properly considered.

Azimuthal correlations of charged particles in xenon-xenon collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV are studied. The data were collected by the CMS experiment at the LHC with a total integrated luminosity of $3.42\mu {\text{b}}^{-1}$. The collective motion of the system formed in the collision is parametrized by a Fourier expansion of the azimuthal particle density distribution. The azimuthal anisotropy coefficients $v_2, v_3$, and $v_4$ are obtained by the scalar-product, two-particle correlation, and multiparticle correlation methods. Within a hydrodynamic picture, these methods have different sensitivities to noncollective and fluctuation effects. The dependence of the Fourier coefficients on the size of the colliding system is explored by comparing the xenon-xenon results with equivalent lead-lead data. Model calculations that include initial-state fluctuation effects are also compared to the experimental results. The observed angular correlations provide new constraints on the hydrodynamic description of heavy ion collisions.

Within the framework of BCS theory and the Skyrme-Hartree-Fock model, we employ various microscopic pairing gaps and effective pairing interactions to study pairing effects on the equation of state (EOS) of neutron matter and the symmetry energy at subsaturation densities. We find pairing effects may have considerable contributions to the EOS of neutron matter at very low densities $\left(\lesssim 0.02{\mathrm{fm}}^{-3}\right)$ but only have a small impact on the symmetry energy at subsatruation densities. In addition, the reliability of the parabolic approximation for the isospin asymmetry dependence of nuclear matter EOS with pairing correlations included is also discussed.

We analyze the evolution of hydrodynamic fluctuations in a heavy-ion collision as the system passes close to the QCD critical point. We introduce two small dimensionless parameters $\lambda$ and ${\mathrm{\Delta }}_s$ to characterize the evolution. $\lambda$ compares the microscopic relaxation time (away from the critical point) to the expansion rate $\lambda \equiv {\tau }_0/{\tau }_Q$, and ${\mathrm{\Delta }}_s$ compares the baryon to entropy ratio, $n/s$, to its critical value, ${\mathrm{\Delta }}_s\equiv (n/s-n_c/s_c)/(n_c/s_c)$. We determine how the evolution of critical hydrodynamic fluctuations depends parametrically on $\lambda$ and ${\mathrm{\Delta }}_s$. Finally, we use this parametric reasoning to estimate the critical fluctuations and correlation length for a heavy-ion collision and to give guidance to the experimental search for the QCD critical point.

The large values of the singlet and triplet scattering lengths locate the two-nucleon system close to the unitary limit, the limit in which these two values diverge. As a consequence, the system shows a continuous scale invariance, which strongly constrains the values of the observables, a well-known fact already noticed a long time ago. For example, the triton binding energy is correlated with other observables such as the doublet nucleon-deuteron scattering length or the $\alpha$-particle binding energy. Moreover, the low-energy dynamics of these systems is universal; it does not depend on the details of the nuclear interaction. Instead, it depends on a few control parameters such as the (large) values of the scattering lengths and the triton binding energy. Using a potential model in order to vary the values of the scattering lengths, we study the spectrum of $A=2,3,4,6$ nuclei in the region between the unitary limit and the point where the scattering lengths get their physical values. In particular, we analyze how the binding energies emerge from the unitary limit forming the observed levels.

As a neutron scatters from a target nucleus, there is a small but measurable effect caused by the interaction of the neutron's magnetic dipole moment with that of the partially screened electric field of the nucleus. This spin-orbit interaction is typically referred to as Schwinger scattering and induces a small rotation of the neutron's spin on the order of ${10}^{-4}\mathrm{rad}$ for Bragg diffraction from silicon. In our experiment, neutrons undergo greater than 100 successive Bragg reflections from the walls of a slotted, perfect-silicon crystal to amplify the total spin rotation. A magnetic field is employed to ensure constructive addition as the neutron undergoes this series of reflections. The strength of the spin-orbit interaction, which is directly proportional to the electric field, was determined by measuring the rotation of the neutron's spin-polarization vector. Our measurements show good agreement with the expected variation of this rotation with the applied magnetic field, while the magnitude of the rotation is $\approx 40\%$ larger than expected.

We introduce the idea of estimating the interaction between substructures in many-body systems by considering them to be independent except for the fact that they live in model spaces whose dimensionality is effectively reduced due to each other's Pauli blocking. We apply this idea to the study of isovector pairing correlations within the the quartet condensation model, based on the improved analytical relations method. We study both $N=Z$ and $N>Z$ nuclei, where a natural decomposition may be performed in terms of quartet and pair degrees of freedom.

Background: There has been a considerable interest focused on the study of enhancement or suppression in collectivity of the excited $2_1^{+}$ states in stable Sn isotopes. Independent measurements of Coulomb excitation cross sections and $2_1^{+}$ level lifetimes report discrepant transition probabilities. Existing estimates for $2_1^{+}$ lifetime indicate reduced collectivity.

Purpose: A reexamination of lifetime of the $2_1^{+}$ state in the most abundant ${}^{120}\mathrm{Sn}$ isotope is thus warranted. The same has been carried out in the present work and the result has been used to determine the transition probability as an indicative of the underlying collectivity.

Methods: Low-lying levels in the vibrational ${}^{120}\mathrm{Sn}$ nucleus have been excited by inelastic scattering with ${}^{32}\mathrm{S}$ beam at $E_{\mathrm{lab}}=120$ MeV. Level lifetime measurements have been carried out using the Doppler shift attenuation method, wherein the Doppler affected $\gamma$-ray peaks have been analyzed using updated methodologies.

Results: From the measured lifetime of the $2_1^{+}$ state ($E_x=1171$ keV) in ${}^{120}\mathrm{Sn}, {\tau }_{2_1^{+}}=0.{863}_{-0.036}^{+0.029}$ ps, a value of $B(E2;0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+})=0.{215}_{+0.009}^{-0.007}$ is deduced. An estimate of the $4_1^{+}$ (feeder) level lifetime, ${\tau }_{4_1^{+}}=1.{77}_{-0.089}^{+0.084}$ ps, is also reported from lineshape analysis of $\gamma$ rays in cascade.

Conclusions: An enhancement in collectivity for the $2_1^{+}$ state is confirmed, following an improved determination of the level lifetime, with reduced uncertainties. The excited $2_1^{+}$ state is also found to have a nonvanishing moment of inertia, suggesting anharmonic nature of quadrupole vibrations.

The experimental features of positive-parity doublet bands in the odd-$A$ cesium isotopes ${}^{125,127,129,131}\mathrm{Cs}$, including angular momentum alignment, energy staggering, $B\left(M1\right)/B\left(E2\right)$, etc. are studied systematically and compared to those of the candidate chiral bands in the adjacent odd-odd Cs isotopes. The configuration assignments and the dynamics of these bands are discussed. The self-consistent tilted axis cranking relativistic mean-field calculations are performed with configuration reassigned to these bands. The experimental level schemes of four nuclei are well reproduced, and the calculations also show four nuclei have obvious triaxial deformations and thus support the candidate chiral doublet bands in ${}^{125,127,129,131}\mathrm{Cs}$.

Two features, a slow slope and a sharp drop, in neutron-induced total nonelastic cross sections in ${}^{27}\mathrm{Al}$ and ${}^{208}\mathrm{Pb}$ are analyzed within the framework of an intranuclear cascade (INC) model. First, to reproduce the slow slope from 100 to 10 MeV, the original INC is generalized in two points; a method to construct the ground state of the target nucleus and a method of taking the effective two-body cross sections between two nucleons. Second, to analyze the origin of the sharp drop from 10 MeV to nearly 1 MeV, the INC is extended to include quantum effects which are originated from the existence of the discrete levels in the nuclear potential. It is shown that this extension leads to the sharp drops in the very low energy below around 10 MeV. It is concluded that the INC model can be extended to explain the sharp drops in addition to the slow slope in neutron-induced nonelastic cross sections for ${}^{27}\mathrm{Al}$ and ${}^{208}\mathrm{Pb}$ in the energy region from 100 MeV down to 1 MeV.

Background: Double charge exchange (DCE) nuclear reactions have recently attracted much interest as tools to provide experimentally driven information about nuclear matrix elements of interest in the context of neutrinoless double-$\beta$ decay. In this framework, a good description of the reaction mechanism and a complete knowledge of the initial and final-state interactions are mandatory. Presently, not enough is known about the details of the optical potentials and nuclear response to isospin operators for many of the projectile-target systems proposed for future DCE studies. Among these, the ${}^{20}\mathrm{Ne}+{}^{76}\mathrm{Ge}$ DCE reaction is particularly relevant due to its connection with ${}^{76}\mathrm{Ge}$ double-$\beta$ decay.

Purpose: We intend to characterize the initial-state interaction for the ${}^{20}\mathrm{Ne}+{}^{76}\mathrm{Ge}$ reactions at 306 MeV bombarding energy and determine the optical potential and the role of the couplings between elastic channel and inelastic transitions to the first low-lying excited states.

Methods: We determine the experimental elastic and inelastic scattering cross-section angular distributions, compare the theoretical predictions by adopting different models of optical potentials with the experimental data, and evaluate the coupling effect through the comparison of the distorted-wave Born approximation calculations with the coupled channels ones.

Results: Optical models fail to describe the elastic angular distribution above the grazing angle ($\approx {9.4}^{\circ }$). A correction in the geometry to effectively account for deformation of the involved nuclear systems improves the agreement up to about ${14}^{\circ }$. Coupled channels effects are crucial to obtain good agreement at large angles in the elastic scattering cross section.

Conclusions: The analysis of elastic and inelastic scattering data turned out to be a powerful tool to explore the initial and final-state interactions in heavy-ion nuclear reactions at high transferred momenta.

We study the medium-induced gluon emission process experienced by a hard jet parton propagating through the dense nuclear matter in the framework of deep inelastic scattering off a large nucleus. We work beyond the collinear rescattering expansion and the soft-gluon emission limit, and we derive a closed formula for the medium-induced single gluon emission spectrum from a heavy or light quark jet interacting with the dense nuclear medium via transverse and longitudinal scatterings. Without performing the collinear rescattering expansion, the medium-induced gluon emission spectrum is controlled by the full distribution of the differential elastic scattering rates between the propagating partons and the medium constituents. We further show that if one utilizes heavy static scattering centers for the traversed nuclear matter and takes the soft-gluon emission limit, our result can reduce to the first order in opacity Djordjevic-Gyulassy-Levai-Vitev formula.

By exploiting the underlying symmetries of the relative phases of the pseudoscalar meson photoproduction amplitude, we provide a consistent and explicit mathematical derivation of the completeness condition for the observables in this reaction. In particular, we determine all the possible sets of four double-spin observables that resolve the phase ambiguity of the amplitude in transversity basis up to an overall phase. The present work substantiates and corroborates the original findings of Chiang and Tabakin [Phys. Rev. C 55, 2054 (1997)]. It is found, however, that the completeness condition of four double-spin observables to resolve the phase ambiguity holds only when the relative phases do not meet the condition of equal magnitudes. In situations where this condition occurs, it is shown that one needs extra chosen observables, resulting in the minimum number of observables required to resolve the phase ambiguity reaching up to eight, depending on the particular set of four double-spin observables considered. Furthermore, a way of gauging when the condition of equal magnitudes occurs is provided.

We have proposed in a series of previous articles a method to determine the effective axial-vector current coupling and the strength of the isoscalar proton-neutron pairing interaction for calculating the nuclear matrix elements of the neutrinoless double-$\beta$ ($0\nu \beta \beta$) decay by the quasiparticle random-phase approximation (QRPA). The combination of these two parameters has had an uncertainty in the QRPA approach, but now this uncertainty is removed by introducing a mathematical identity derived under the closure approximation to the nuclear matrix element of the $0\nu \beta \beta$ decay. In this article, we apply our method to the $0\nu \beta \beta$ decays of ${}^{136}\mathrm{Xe}$ and ${}^{130}\mathrm{Te}$ and show the nuclear matrix elements and reduced half-lives. Our calculation is tested first by a self-check method using the two-neutrino double-$\beta$ decay, and this test ensures the application of our method to ${}^{136}\mathrm{Xe}$. It turns out, however, that our method is not successful in ${}^{130}\mathrm{Te}$. Further tests are made for our calculation, and satisfactory results are obtained for ${}^{136}\mathrm{Xe}$.

We have investigated the use of a pure spin-3/2 propagator with consistent interaction Lagrangians to describe the property of spin-3/2 resonance. For this purpose, we use the antisymmetric tensor spinor representation. By using the primary and secondary constraints, we obtain the interaction fields that have the correct degrees of freedom. To visualize the result, we calculate the contribution of spin-3/2 $\mathrm{\Delta }$ resonance to the total cross section of pion scattering and pion photoproduction off the nucleon. The result confirms that the scattering and photoproduction amplitudes obtained from the pure spin-3/2 representation with consistent interaction Lagrangians exhibit the required property of resonance. Therefore, the formalism can be used for phenomenological investigations in the realm of nuclear and particle physics.

We calculate the bulk-viscous dissipation time for adiabatic density oscillations in nuclear matter at densities of one to seven times the nuclear saturation density and at temperatures ranging from 1 MeV, where corrections to previous low-temperature calculations become important, up to 10 MeV, where the assumption of neutrino transparency is no longer valid. Under these conditions, which are expected to occur in neutron star mergers, damping of density oscillations arises from $\beta$ equilibration via weak interactions. We find that for 1-kHz oscillations the shortest dissipation times are in the 5- to 20-ms range, depending on the equation of state, which means that bulk viscous damping could affect the dynamics of a neutron star merger. For higher frequencies, the dissipation time can be even shorter.