Balance functions have been measured in terms of relative pseudorapidity ($\mathrm{\Delta }\eta$) for charged particle pairs at the BNL Relativistic Heavy Ion Collider from Au + Au collisions at $\sqrt{s_{\mathrm{NN}}}=7.7\mathrm{GeV}$ to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76\mathrm{TeV}$ by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at $\sqrt{s_{\mathrm{NN}}}=7.7$ GeV implies that a QGP is still being created at this relatively low energy.

In this paper we study yrast states of ${}^{128,126,124}\mathrm{Sn}$ and ${}^{104,106,108}\mathrm{Sn}$ by using the monopole-optimized realistic interactions in terms of both the shell model (SM) and the nucleon-pair approximation (NPA). For yrast states of ${}^{128,126}\mathrm{Sn}$ and ${}^{104,106}\mathrm{Sn}$, we calculate the overlaps between the wave functions obtained in the full SM space and those obtained in the truncated NPA space, and find that most of these overlaps are very close to 1. Very interestingly, for most of these states with positive parity and even spin or with negative parity and odd spin, the SM wave function is found to be well represented by one nucleon-pair basis state, viz., a simple picture of “nucleon-pair states” (nucleon-pair configuration without mixings) emerges. In ${}^{128,126}\mathrm{Sn}$, the positive-parity (or negative-parity) yrast states with spin $J>10$ (or $J>7$) are found to be well described by breaking one or two $S$ pairs in the ${10}_1^{+}$ (or $7_1^{-}$) state, i.e., the yrast state of seniority-two, spin-maximum, and positive-parity (or negative-parity), into non-$S$ pair(s). Similar regularity is also pointed out for ${}^{104,106}\mathrm{Sn}$. The evolution of $E2$ transition rates between low-lying states in ${}^{128,126,124}\mathrm{Sn}$ is discussed in terms of the seniority scheme.

We calculate the correlation parameter $\kappa$ of symmetric nuclear matter in the Brueckner-Hartree-Fock approximation obtained with various modern nucleon-nucleon potentials of high precision. We point out qualitative differences between the potentials and elucidate the consequences for momentum distributions, defect functions, and convergence of the hole-line expansion. The important role of the tensor force is emphasized.

Background: Nuclear short-range correlations (SRCs) are corrections to mean-field wave functions connected with the short-distance behavior of the nucleon-nucleon interaction. These SRCs provide corrections to lepton-nucleus cross sections as computed in the impulse approximation (IA).

Purpose: We want to investigate the influence of SRCs on the one-nucleon ($1N$) and two-nucleon ($2N$) knockout channels for muon-neutrino induced processes on a ${}^{12}\mathrm{C}$ target at energies relevant for contemporary measurements.

Method: The model adopted in this work corrects the impulse approximation for SRCs by shifting the complexity induced by the SRCs from the wave functions to the operators. Due to the local character of the SRCs, it is argued that the expansion of these operators can be truncated at a low order.

Results: The model is compared with electron-scattering data, and two-particle two-hole responses are presented for neutrino scattering. The contributions from the vector and axial-vector parts of the nuclear current as well as the central, tensor, and spin-isospin parts of the SRCs are studied.

Conclusions: Nuclear SRCs affect the $1N$ knockout channel and give rise to $2N$ knockout. The exclusive neutrino-induced $2N$ knockout cross section of SRC pairs is shown and the $2N$ knockout contribution to the QE signal is calculated. The strength occurs as a broad background which extends into the dip region.

Background: Reactions with stable beams have demonstrated strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments.

Purpose: To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei.

Method: Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in ${}^{40-54}\text{Ca}+{}^{116}\text{Sn}$ reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations.

Results: The development of a neutron skin in exotic calcium isotopes strongly lowers the bare potential barrier. However, this static effect is not apparent when dynamical effects are included. On the contrary, a fusion hindrance is observed in TDHF calculations with the most neutron-rich calcium isotopes which cannot be explained by vibrational couplings. Transfer reactions are also important in these systems due to charge equilibration processes.

Conclusions: Despite its impact on the bare potential, the neutron skin is not seen as playing an important role in the fusion dynamics. However, the charge transfer with exotic projectiles could lead to an increase of the Coulomb repulsion between the fragments, suppressing fusion. The effects of transfer and dissipative mechanisms on fusion with exotic nuclei deserve further studies.

We generalize calculations of the energy-momentum tensor for classical gluon fields in the boost-invariant McLerran-Venugopalan model using the small-$\tau$ power series expansion method. Results to all orders for the energy density and pressures are given in the leading $Q^2$ approximation and with the inclusion of estimated running coupling effects. The energy density and transverse pressure decrease monotonically with time while the longitudinal pressure starts from a negative value and increases towards zero.

We explore the breaking of Lorentz and $\mathit{CPT}$ invariance in strong interactions at low energy in the framework of chiral perturbation theory. Starting from the set of Lorentz-violating operators of mass-dimension five with quark and gluon fields, we construct the effective chiral Lagrangian with hadronic and electromagnetic interactions induced by these operators. We develop the power-counting scheme and discuss loop diagrams and the one-pion-exchange nucleon-nucleon potential. The effective chiral Lagrangian is the basis for calculations of low-energy observables with hadronic degrees of freedom. As examples, we consider clock-comparison experiments with nuclei and spin-precession experiments with nucleons in storage rings. We derive strict limits on the dimension-five tensors that quantify Lorentz and $\mathit{CPT}$ violation.

The missing mass spectroscopy of the ${}_{\mathrm{\Lambda }}{}^7\mathrm{He}$ hypernucleus was performed using the ${}^7\mathrm{Li}(e,e^{\prime }{K}^{+}){}_{\mathrm{\Lambda }}{}^7\mathrm{He}$ reaction at the Thomas Jefferson National Accelerator Facility Hall C. The $\mathrm{\Lambda }$-binding energy of the ground-state ($1/2^{+}$) was determined with a smaller error than that of the previous measurement, being $B_{\mathrm{\Lambda }}=5.55\pm 0.{10}^{\mathrm{stat}.}\pm 0.{11}^{\mathrm{sys}.}\mathrm{MeV}$. The experiment also provided new insight into charge symmetry breaking in $p$-shell hypernuclear systems. Finally, a peak at $B_{\mathrm{\Lambda }}=3.65\pm 0.{20}^{\mathrm{stat}.}\pm 0.{11}^{\mathrm{sys}.}\mathrm{MeV}$ was observed and assigned as a mixture of $3/2^{+}$ and $5/2^{+}$ states, confirming the “gluelike” behavior of $\mathrm{\Lambda }$, which makes an unstable state in ${}^6\mathrm{He}$ stable against neutron emission.

The $\beta$ decay of ${}^{124}\mathrm{Cd}$ into levels in ${}^{124}\mathrm{In}$ was reinvestigated at the Holifield Radioactive Ion Beam Facility. Fifty-MeV protons were bombarded on uranium targets and the induced fission products were mass separated and deposited on a moving tape in the center of an array of $\gamma$ detectors. The resulting $\gamma -\gamma$ coincidences revealed appreciable disagreement with previous work and has resulted in a revised ordering of the low-energy states in ${}^{124}\mathrm{In}$. The resulting partial decay scheme has four energy levels, three of which are new.

An earlier coexistence model of Ge nuclei is applied to $E2$ strengths connecting low-lying $0^{+}$ and $2^{+}$ states in ${}^{72}\mathrm{Ge}$. New data have smaller uncertainties and, for the first time, a value for the transition strength from the third $2^{+}$ state to the second $0^{+}$ state. This $B$($E2$) for the third $2^{+}$ state clearly indicates that it is the one that should be included in the mixing, rather than the second $2^{+}$ state. My results confirm that the $0^{+}$ states are maximally mixed, the $2^{+}$ states are weakly mixed, and the $E2$ matrix element involving the lower $0^{+}$ basis state is significantly larger than the one involving the second $0^{+}$ basis state.

The decays of two isomeric states in the neutron-rich nucleus ${}^{75}\mathrm{Cu}$ have been studied via delayed $\gamma$-ray spectroscopy. These states were populated by the fragmentation of a $60.4A\mathrm{MeV} {}^{86}\mathrm{Kr}$ primary beam, which impinged on a Be target at the LISE2k spectrometer of GANIL. Isomeric half-lives and branching ratios were measured, and a $\gamma -\gamma$ coincidence analysis performed. These have allowed a revised level scheme of ${}^{75}\mathrm{Cu}$ to be proposed. A comparison with large-scale shell-model calculations using different effective interactions and valence spaces shows the importance of proton excitations across the $Z=28$ shell gap for reproducing the energy spacing between the isomeric states. The coexisting collective and single-particle properties of the $(1/2^{-})$ and $(3/2^{-})$ states, respectively, are similar to those of the same states in the neighboring ${}^{69,71,73}\mathrm{Cu}$. The small energy spacings between the $(1/2^{-}), (3/2^{-})$, and $5/2^{-}$ states are responsible for the isomerism.

The effects of nuclear isospin asymmetry on $\alpha$-decay lifetimes of heavy nuclei are investigated within various phenomenological models of the nuclear potential for the $\alpha$ particle. We consider the widely used simple square-well potential and Woods-Saxon potential and modify them by including an isospin asymmetry term. We then suggest a model for the potential of the $\alpha$ particle motivated by a microscopic phenomenological approach of the Skyrme force model, which naturally introduces the isospin-dependent form of the nuclear potential for the $\alpha$ particle. The empirical $\alpha$-decay lifetime formula of Viola and Seaborg [J. Inorg. Nucl. Chem. 28, 741 (1966)] is also modified to include isospin asymmetry effects. The obtained $\alpha$-decay half-lives are in good agreement with the experimental data, and we find that including the nuclear isospin effects somehow improves the theoretical results for $\alpha$-decay half-lives. The implications of these results are discussed, and the predictions on the $\alpha$-decay lifetimes of superheavy elements are also presented.

Recently a quantitative description of the two-neutron transfer reaction ${}^{12}\mathrm{C}({}^{18}\mathrm{O},{}^{16}\mathrm{O}){}^{14}\mathrm{C}$ was performed and the measured cross sections were successfully reproduced [M. Cavallaro et al., Phys. Rev. C 88, 054601 (2013)]. This task was accomplished by combining nuclear structure calculations of spectroscopic amplitudes and a full quantum description of the reaction mechanism. Verification of such a theoretical approach to other heavy nuclear systems is mandatory in order to use (${}^{18}\mathrm{O},{}^{16}\mathrm{O}$) reactions to assess pair configurations in nuclear states. In this work we apply this methodology to the ${}^{16}\mathrm{O}({}^{18}\mathrm{O},{}^{16}\mathrm{O}){}^{18}\mathrm{O}$ reaction at 84 MeV. Experimental angular distributions for the two-neutron transfer to the ground state and $2_1^{+}$ state of ${}^{18}\mathrm{O}$ were obtained using the MAGNEX spectrometer at INFN-LNS. The roles of one- and two-step processes are analyzed under the exact finite range coupled reaction channel and the second order distorted wave Born approximation. We conclude that the one-step transfer mechanism is dominant in this system.

We quantitatively estimate properties of the quark-gluon plasma created in ultrarelativistic heavy-ion collisions utilizing Bayesian statistics and a multiparameter model-to-data comparison. The study is performed using a recently developed parametric initial condition model, ${\mathrm{T}}_{\mathrm{R}}\text{ENTo}$, which interpolates among a general class of particle production schemes, and a modern hybrid model which couples viscous hydrodynamics to a hadronic cascade. We calibrate the model to multiplicity, transverse momentum, and flow data and report constraints on the parametrized initial conditions and the temperature-dependent transport coefficients of the quark-gluon plasma. We show that initial entropy deposition is consistent with a saturation-based picture, extract a relation between the minimum value and slope of the temperature-dependent specific shear viscosity, and find a clear signal for a nonzero bulk viscosity.

We calculated the half-life times ($T_c$) of the ${}^{14}\mathrm{C}, {}^{20}\mathrm{O}, {}^{20}\mathrm{Ne}$, and ${}^{24}\mathrm{Ne}$ cluster emissions from heavy and superheavy nuclei. The variation of $T_c$ with the neutron and proton numbers of daughter nuclei is studied to determine the minima in ${log}_{10}{T}_c$ at each neutron number for different daughter isotones. We found that each minimum for a given isotone corresponds to neutron magicity already indicated by other approaches. The proton numbers at neutron magic numbers were found to be also proton magic numbers or differ slightly from them. We arranged the different isotones at each neutron magic number according to their stability in the sense that the more stable daughter isotone corresponds to the lowest value of ${log}_{10}{T}_c$. The magic neutron numbers predicted by the present study are $N=126$, 148, 152, 154, 160, 162, 172, 176, 178, 180, 182, 184, and 200. The predicted magic proton numbers are $Z=82$, 98, 100 102, 106, 108, 114, and 116. The values of $N$ and $Z$ mentioned above agree with magic numbers deduced in other studies.

We use the breakup absorption model to simultaneously describe the measured cross sections of complete fusion (CF), incomplete fusion (ICF), and total fusion (TF) in nuclear reactions induced by weakly bound nuclei ${}^{6,7}\mathrm{Li}$ on ${}^{209}\mathrm{Bi}$ and ${}^{198}\mathrm{Pt}$ targets. The absorption cross sections are calculated using the continuum discretized coupled channels (CDCC) method with different choices of short-range imaginary potentials to get the ICF, CF, and TF cross sections. It is observed that the cross sections for deuteron ICF / deuteron capture and $\alpha$ ICF / $\alpha$ capture are of similar magnitude, in the case of the ${}^6\mathrm{Li}$ projectile, while the cross sections for the triton ICF / triton capture is more dominant than that of $\alpha$ ICF / $\alpha$ capture in the case of the ${}^7\mathrm{Li}$ projectile. Both these observations are also corroborated by the experimental data. The ratio of ICF to TF cross sections, which defines the value of fusion suppression factor, is found to be in agreement with the data available from the literature. The cross-section ratios of CF/TF and ICF/TF show opposite behavior at below-barrier energies the former decreases while the latter increases as the energy is lowered, which shows the dominance of ICF at below-barrier energies. We have also studied the correlation of the ICF cross sections with the noncapture breakup (NCBU) cross sections as a function of energy, which shows that the NCBU is more significant than ICF at below-barrier energies.

Pairing gaps in neutron matter need to be computed in a wide range of densities to address open questions in neutron-star phenomenology. Traditionally, the Bardeen-Cooper-Schrieffer approach has been used to compute gaps from bare nucleon-nucleon interactions. Here we incorporate the influence of short- and long-range correlations in the pairing gaps. Short-range correlations are treated, including the appropriate fragmentation of single-particle states, and substantially suppress the gaps. Long-range correlations dress the pairing interaction via density and spin modes and provide a relatively small correction. We use different interactions, some with three-body forces, as a starting point to control for any systematic effects. Results are relevant for neutron-star cooling scenarios, in particular in view of the recent observational data on Cassiopeia A.

The triple $\alpha$-decay chain ${}^{114}\mathrm{Ba}\to {}^{110}\mathrm{Xe}\to {}^{106}\mathrm{Te}\to {}^{102}\mathrm{Sn}$ has been directly observed for the first time, following the ${}^{58}\mathrm{Ni}\left({}^{58}\mathrm{Ni},2n\right)$ reaction. Implantation of ${}^{114}\mathrm{Ba}$ nuclei into a double-sided silicon-strip detector has allowed their $\alpha$ decays to be correlated in position and time with the $\alpha$ decays of the daughter $\left({}^{110}\mathrm{Xe}\right)$ and granddaughter $\left({}^{106}\mathrm{Te}\right)$ nuclei. In total, 17 events have been assigned to the ${}^{114}\mathrm{Ba}\to {}^{110}\mathrm{Xe}\to {}^{106}\mathrm{Te}\to {}^{102}\mathrm{Sn}$ triple $\alpha$-decay chain. The energy of the ${}^{114}\mathrm{Ba} \alpha$ decay has been measured to be $E_{\alpha }=3480$(20) keV, which is 70 keV higher than the previously measured value, and the half-life of ${}^{114}\mathrm{Ba}$ has been measured with improved accuracy, to be ${380}_{-110}^{+190}$ ms. A revised $Q_{{}^{12}\mathrm{C}}$ value of 19 035(45) keV for ${}^{114}\mathrm{Ba}$ is presented.

We further investigate the cluster emission from heavy nuclei beyond the lead region in the framework of the preformed cluster model. The refined cluster-core potential is constructed by the double-folding integral of the density distributions of the daughter nucleus and the emitted cluster, where the radius or the diffuseness parameter in the Fermi density distribution formula is determined according to the available experimental data on the charge radii and the neutron skin thickness. The Schrödinger equation of the cluster-daughter relative motion is then solved within the outgoing Coulomb wave-function boundary conditions to obtain the decay width. It is found that the present decay width of cluster emitters is clearly enhanced as compared to that in the previous case, which involved the fixed parametrization for the density distributions of daughter nuclei and clusters. Among the whole procedure, the nuclear deformation of clusters is also introduced into the calculations, and the degree of its influence on the final decay half-life is checked to some extent. Moreover, the effect from the bubble density distribution of clusters on the final decay width is carefully discussed by using the central depressed distribution.