We analyze the forward-backward multiplicity correlation coefficient as measured by STAR. We show that in the most central Au $+$ Au collisions bins located symmetrically around $\eta =0$ with large separation in pseudorapidity are more strongly correlated than bins located asymmetrically with smaller separation. In proton-proton collisions the opposite effect is observed. It suggests a qualitatively different behavior of the two-particle correlation as a function of pseudorapidity sum in $p+p$ and Au+Au collisions.

The single-freeze-out model with parametrized hypersurface and flow geometry is employed to analyze the transverse-momentum spectra of hadrons produced in the Pb+Pb collisions at the collision energy of $\sqrt{s_{NN}}=2.76$ TeV at the CERN Large Hadron Collider (LHC). With the notable exception for protons and antiprotons, we find a very good agreement between the model results and the data for the measured hadron species. The additional analysis of the Hanbury-Brown–Twiss (HBT) radii of pions helps us to select, from several different types of freeze-out studied in this work, the most realistic form of the freeze-out hypersurface. We find that the discrepancy ratio between the model and experiment for the proton and antiproton spectra depends on $p_T$, dropping from 2 in the soft region to 1 around $p_T=1.5$ GeV.

We report on the observation of $\alpha$ decay from a state in ${}^{10}$B at 11.48 MeV. The only observed decay branch is to the first $T=1$ state in ${}^6$Li at 3.56 MeV. The apparent absence of an $\alpha$-decay branch to the ($T=0$) ground state in ${}^6$Li suggests that the 11.48-MeV state should be assigned isospin $T=1$. The spin and parity of the 11.48-MeV state could not be directly determined from the present study apart from $J=0$ being ruled out by the observed angular correlation. We conjecture that the 11.48-MeV state is the analog of the 10.15-MeV, $\left(4^{+}\right)$ state in ${}^{10}$Be, constitutes the third member of a rotational band built on the $0^{+}$ state at 7.65 MeV, and has pronounced molecular structure.

We investigate the shape phase transition in even-even ${}_{64}$Gd and ${}_{66}$Dy isotopes within the proton-neutron interacting boson model (IBM-2). The parameters of the IBM-2 Hamiltonian are fixed in two different ways: the usual phenomenological fitting calculation and the mapping of the constrained self-consistent mean-field calculation with a Skyrme energy density functional onto the appropriate boson system. Notable differences are found between the energy surfaces for the phenomenological and the mapped IBM-2. Key quantities for the collective structural evolution, including level energies, $B\left(\mathrm{E}2\right)$ values, quadrupole moments, and the two-neutron separation energies, are analyzed in comparison to the experimental data. We show that the transition in these quantities occurs rapidly with the neutron number in the IBM-2 phenomenology but is somewhat smeared out in the mapped IBM-2. The differences in the measurable quantities are consistent with what is suggested by the energy-surface analysis.

We investigate the phenomenon of core excitation in the inelastic and breakup of two-body halo nuclei, composed by a valence nucleon and a core. To evaluate the importance of this effect we propose a simple reaction model based on an extension of the standard distorted wave Born approximation (DWBA) method. The model takes into account core-excited admixtures in the states of the composite projectile, as well as the possibility of dynamic core excitation due to the interaction of the core with the target. As an application of the model, we present calculations for the breakup of ${}^{11}$Be on a proton target at an incident energy of 63.7 MeV/nucleon, comparing it with the available data for this reaction. We find that the data are well reproduced by the model and that the effect of dynamic core excitation is essential to explain the observed cross section.

We present new features of fragmentation dynamics at the transition from semicentral to semiperipheral heavy-ion collisions at Fermi energies, as obtained within a microscopic transport model, the stochastic mean field. We show that, along this transition, specific hierarchy phenomena of some kinematic observables associated with the intermediate mass fragments develop. Their correlations with the dynamics of the isospin degree of freedom, predicted by our calculations, open new possibilities to learn about the density dependence of nuclear symmetry energy below saturation, as well as about the relevant fragmentation mechanisms. Detailed results are presented for mass symmetric $\text{Sn}+\text{Sn}$ reactions with different isospin content at 50 MeV/nucleon.

Various types of nuclear proximity potentials are employed to study the cluster decay of radioactive nuclei, particularly those decaying to a doubly closed shell ${}^{208}$Pb-daughter nucleus using the preformed cluster-decay model (PCM). The deformation effect is included up to quadrupole (${\beta }_2$) with “optimum” cold orientations. The use of different proximity potentials modifies the potential barrier characteristics (i.e., barrier height, position, and frequency), which in turn change the preformation probability $P_0$ and tunneling probability $P$, and hence the decay half-life considerably. The analysis of ${}^{208}$Pb-daughter cluster radioactivity is worked out at touching as well as at an elongated neck configuration by taking the neck-length parameter $\Delta R=0.5$ fm. A wide range of barrier characteristics is covered by using various nuclear proximity potentials. We observe that Prox 1977 and Prox 1988 can reproduce the experimental half-lives very well at $\Delta R=0.5$ fm; however, the use of the mod-Prox 1988 potential seems more reliable for ${}^{14}$C cluster decay. The relevance of barrier characteristics of other nuclear proximity potentials is also explored in the context of ${}^{208}$Pb cluster radioactivity.

We utilize a light-front relativistic quark model (LF RQM) to predict the $3q$ core contribution to the electroexcitation amplitudes for $\Delta \left(1232\right)$$P$${}_{33}$, $N$(1440)$P$${}_{11}$, $N$(1520)$D$${}_{13}$, and $N$(1535)$S$${}_{11}$ up to $Q^2=12$ GeV${}^2$. The parameters of the model have been specified via description of the nucleon electromagnetic form factors in the approach that combines $3q$ and pion-cloud contributions in the LF dynamics.

We present state-of-the-art shell-model calculations in a large model space ($pf$ for protons, $fpgd$ for neutrons), which allows us to study simultaneously excitations across the $Z=28$ and $N=50$ shell gaps. We explore the region in the vicinity of ${}^{78}$Ni, which is a subject of intense experimental investigations. Our calculations correctly account for the known low-lying excited states in this region, including those which may correspond to cross-shell excitations. We observe the minimum of the $N=50$ mass gap at $Z=32$ consistent with experimental data and its further increase toward $Z=28$, indicating a robustness of the $N=50$ gap in ${}^{78}$Ni. The evolution of the $N=50$ gap along the nickel chain is shown to bear similarities to what is known in oxygen and calcium chains, providing a new opportunity for the studies of three-body monopole effects in medium-mass nuclei.

We describe a symmetry-preserving calculation of the light-quark meson spectrum, which combines a description of pion properties with reasonable estimates of the masses of heavier mesons, including axial-vector states. The kernels used in formulating the problem are essentially nonperturbative, incorporating effects of dynamical chiral symmetry breaking (DCSB) that were not previously possible to express. Our analysis clarifies a causal connection between DCSB and the splitting between vector and axial-vector mesons and exposes a key role played by the anomalous chromomagnetic moment of dressed quarks in forming the spectrum.

The fission probability of ${}^{232}$Pa was measured as a function of the excitation energy in order to search for hyperdeformed (HD) transmission resonances using the ($d,pf$) transfer reaction on a radioactive ${}^{231}$Pa target. The experiment was performed at the Tandem accelerator of the Maier-Leibnitz Laboratory (MLL) at Garching using the ${}^{231}$Pa($d,pf$) reaction at a bombarding energy of $E_d=12$ MeV and with an energy resolution of $\Delta E=5.5$ keV. Two groups of transmission resonances have been observed at excitation energies of $E^{*}=5.7$ and 5.9 MeV. The fine structure of the resonance group at $E^{*}=5.7$ MeV could be interpreted as overlapping rotational bands with a rotational parameter characteristic to a HD nuclear shape (${\hslash }^2/2\Theta =2.10\pm 0.15$ keV). The fission barrier parameters of ${}^{232}$Pa have been determined by fitting talys 1.2 nuclear reaction code calculations to the overall structure of the fission probability. From the average level spacing of the $J=4$ states, the excitation energy of the ground state of the third minimum has been deduced to be $E_{\text{III}}={5.05}_{-0.10}^{+0.40}$ MeV.

Odd-odd nuclei are good candidates for probing possible structure changes away from the valley of stability. By using the projected shell model in which deformed Nilsson single-particle states are taken to build the model basis, we study band properties in odd-odd Mn ($Z=25$) isotopes with neutron number $N=33,35$, and 37. With the help of model analysis, we interpret the low-lying positive-parity states in these nuclei in terms of their intrinsic structures. Our study on high-spin negative-parity states explores the important role of the neutron $g_{9/2}$ orbit in this mass region.

The ${}^{114}$Sn($p$,$t$)${}^{112}$Sn reaction has been investigated in a high resolution experiment at incident proton energy of 22 MeV. Angular distributions for 28 transitions to levels of ${}^{112}$Sn up to the excitation energy of 3.624 MeV have been measured. The spin and parity identification has been carried out by means of a distorted-wave Born approximation (DWBA) analysis, performed by using conventional Woods-Saxon potentials. A shell-model study of ${}^{112}$Sn nucleus has been performed using a realistic two-body effective interaction derived from the CD-Bonn nucleon-nucleon potential. The energy spectra have been calculated and compared with the experimental ones, while the theoretical two-nucleon spectroscopic amplitudes, evaluated in a truncated seniority space, have been used in the microscopic DWBA calculation of the cross-section angular distributions.

The ${}^{11}$Li breakup on a ${}^{208}$Pb target is studied in the Coulomb-corrected eikonal approximation by using a ${}^9\mathrm{Li}+n+n$ three-body description of the projectile. The ${}^{11}$Li wave functions are defined in the hyperspherical formalism for bound and scattering states and are obtained from effective ${}^9\mathrm{Li}+n$ and $n+n$ interactions. We first determine $0^{+}$, $1^{-}$, and $2^{+}$ ${}^9\mathrm{Li}+n+n$ phase shifts, which suggest the existence of a narrow $1^{-}$ resonance near 0.5 MeV above threshold. The calculated breakup cross sections show a peak at low energies, in agreement with the data. The influence of monopole and quadrupole components is analyzed and shown to be non-negligible. We discuss the derivation of dipole strengths from experimental breakup cross sections and suggest that the simple Coulomb dipole approximation, traditionally used in the literature, should be replaced by more elaborate models. We also show that ${}^{11}\mathrm{Li}+{}^{208}\mathrm{Pb}$ elastic scattering measurements would provide an indirect test of the model.

Nuclear-medium effects on the weak structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ in charged-current neutrino and antineutrino induced deep-inelastic reactions in ${}^{208}$Pb have been studied. The calculations have been performed in a theoretical model using relativistic nuclear spectral functions which incorporate Fermi motion, binding, and nucleon correlations. We have also included the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, differential scattering cross sections have been obtained and compared with the CERN Hybrid Oscillation Research Apparatus (CHORUS) data. The results for the ratios $\frac{2F_i^{Pb}}{208F_i^D}$, $\frac{4F_i^{Pb}}{208F_i^{He}}$, $\frac{12F_i^{Pb}}{208F_i^C}$, $\frac{16F_i^{Pb}}{208F_i^O}$, and $\frac{56F_i^{Pb}}{208F_i^{Fe}}$ ($i=2,3$) have also been obtained and compared with some of the phenomenological fits.

Fusion of very neutron-rich nuclei may be important to determine the composition and heating of the crust of accreting neutron stars. Fusion cross sections are calculated using time-dependent Hartree-Fock theory coupled with density-constrained Hartree-Fock calculations to deduce an effective potential. Systems studied include ${}^{16}$O+${}^{16}$O, ${}^{16}$O+${}^{24}$O, ${}^{24}$O+${}^{24}$O, ${}^{12}$C+${}^{16}$O, and ${}^{12}$C+${}^{24}$O. We find remarkable agreement with experimental cross sections for the fusion of stable nuclei. Our simulations use the SLy4 Skyrme force that has been previously fit to the properties of stable nuclei, and no parameters have been fit to fusion data. We compare our results to the simple São Paulo static barrier penetration model. For the asymmetric systems ${}^{12}$C+${}^{24}$O or ${}^{16}$O+${}^{24}$O we predict an order of magnitude larger cross section than those predicted by the São Paulo model. This is likely due to the transfer of neutrons from the very neutron rich nucleus to the stable nucleus and dynamical rearrangements of the nuclear densities during the collision process. These effects are not included in potential models. This enhancement of fusion cross sections, for very neutron rich nuclei, can be tested in the laboratory with radioactive beams.

In this work, the two-nucleon spectral functions (TNSFs) are defined in terms of the state- and the density-dependent correlation functions in the framework of the lowest-order constrained variational (LOCV) method to calculate the TNSF of the ${}^{16}\text{O}$ nucleus in the ${}^{16}\text{O}$$(e,e^{\prime }NN)$${}^{14}\text{C}$ reaction. The Reid soft-core (Reid68) and the ${\text{Av}}_{18}$ potentials are used as the internucleon interactions. Since, the short-range correlation effects are imposed on the wave functions for the individual channels (e.g., the ${}^1{S}_0$ and ${}^3{P}_J$ channels); therefore, the defect wave functions are obtained for various channels such that the high relative momenta ($p>4{\text{fm}}^{-1}$) are ignored. The resulting TNSFs for the ${}^{16}\text{O}$ nucleus are compared with those of the dressed random phase approximation (DRPA) calculations of Geurts et al. and the experimental predictions, especially those of Onderwater et al., (NIKHEF group), where reasonable agreement is found. It is shown that the optimized state-dependent defect wave functions have substantial effects on the TNSF and it is not justified to use the simplified parametrized two-body correlation functions in all of the channels. In agreement with the experimental data of Onderwater et al., the knockout of a ${}^1{S}_0$ pair proton dominates the above reaction cross section. Finally, it is demonstrated that the $0^{+}$ and $2^{+}$ peaks, which are expected to be observed in the above reaction cross section, are moved to the lower momenta of out-going protons when the state-dependent correlation functions are imposed.

We present a complete analysis of ${}^6\mathrm{Li}+{}^{16}\mathrm{O}$ elastic scattering at 4 and 5 MeV/nucleon. Using either traditional Woods-Saxon or a range of semimicroscopic folding form factors we find that the data require deep, highly transparent potentials. Physically relevant solutions are selected according to the dispersion relation. The intermediate angle structures and the oscillatory increase of the cross section at large angles are interpreted either as a pre-rainbow oscillation resulting from the interference of the barrier and internal barrier far-side scattering subamplitudes or, equally well, as a resonant diffraction arising from two Regge poles located in peripheral waves. Both semiclassical and Regge pole approaches allow a dynamical separation of the resonant component of the $S$ matrix.