We demonstrate how to match pre-equilibrium dynamics of a $0+1$-dimensional quark-gluon plasma to second-order viscous hydrodynamical evolution. The matching allows us to specify the initial values of the energy density and shear tensor at the initial time of hydrodynamical evolution as a function of the lifetime of the pre-equilibrium period. We compare two models for pre-equilibrium quark-gluon plasma, longitudinal free streaming and collisionally broadened longitudinal expansion, and present analytic formulas that can be used to fix the necessary components of the energy-momentum tensor. The resulting dynamical models can be used to assess the effect of pre-equilibrium dynamics on quark-gluon plasma observables. Additionally, we investigate the dependence of entropy production on pre-equilibrium dynamics and discuss the limitations of the standard definitions of nonequilibrium entropy.

We present measurements of the differential cross section and $\Lambda$ recoil polarization for the $\gamma p\to K^{+}\Lambda$ reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from $1.62$ to $2.84$ GeV and a wide range of center-of-mass $K^{+}$ production angles. Independent analyses were performed using the $K^{+}p{\pi }^{-}$ and $K^{+}p$ (missing ${\pi }^{-}$) final-state topologies; results from these analyses were found to exhibit good agreement. These differential-cross-section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300-MeV increase in energy coverage. The recoil polarization data agree well with previous results and offer a large increase in precision and a 500-MeV extension in energy range. The increased center-of-mass energy range that these data represent will allow for independent study of nonresonant $K^{+}\Lambda$ photoproduction mechanisms at all production angles.

The neutron-unbound ground state and two excited states of ${}^{12}\mathrm{Li}$ were formed by the two-proton removal reaction from a 53.4-MeV$/$u ${}^{14}\mathrm{B}$ beam. The decay energy spectrum of ${}^{12}\mathrm{Li}$ was measured with the Modular Neutron Array (MoNA) and the Sweeper dipole superconducting magnet at the National Superconducting Cyclotron Laboratory. Two excited states at resonance energies of 250 $\pm$ 20 keV and 555 $\pm$ 20 keV were observed for the first time and the data are consistent with the previously reported $s$-wave ground state with a scattering length of $a_s=-13.7$ fm.

We present a systematic calculation of $\alpha$-decay half-lives of even-even heavy and superheavy nuclei in the framework of the preformed $\alpha$ model. The microscopic $\alpha$-daughter nuclear interaction potential is calculated by double-folding the density distributions of both $\alpha$ and daughter nuclei with a realistic effective Michigan three-Yukawa nucleon-nucleon interaction, and the microscopic Coulomb potential is calculated by folding the charge density distributions of the two interacting nuclei. The half-lives are found to be sensitive to the density dependence of the nucleon-nucleon interaction and the implementation of the Bohr-Sommerfeld quantization condition inherent in the Wentzel-Kramers-Brillouin approach. The $\alpha$-decay half-lives obtained agree reasonably well with the available experimental data. Moreover, the study has been extended to the newly observed superheavy nuclei. The interplay of closed-shell effects in $\alpha$-decay calculations is investigated. The $\alpha$-decay calculations give the closed-shell effects of known spherical magicities, $Z=82$ and $N=126$, and further predict enhanced stabilities at $N=152,162$, and $184$ for $Z=100,108$, and $114$, owing to the stability of parent nuclei against $\alpha$ decays. It is worth noting that the aim of this work is not only to reproduce the experimental data better, but also to extend our understanding of $\alpha$-decay half-lives around shell closures.

Proton-rich Tc radionuclides have been identified as potential candidates for specific clinical and biological applications in the last decade. So far, these radionuclides have been produced either by proton-induced reaction on Mo targets or $\alpha$-particle-induced reaction on Nb targets. This article lightens two heavy-ion-induced production routes of ${}^{93,94,95,96}\mathrm{Tc}$ radionuclides through ${}^7\mathrm{Li}+{}^{\mathrm{nat}}\mathrm{Zr}$ and ${}^9\mathrm{Be}+{}^{\mathrm{nat}}\mathrm{Y}$ reactions and provides important cross-sectional information in the projectile energy ranges 37–45 MeV and 30–48 MeV, respectively. Excitation functions of those reactions have been measured using the stacked-foil technique followed by the off-line $\gamma$-spectrometric studies. Measured cross-sectional data have been interpreted comparing theoretical predictions of the two nuclear reaction model codes PACE-II and ALICE91. Experimental cross sections agreed with the theory. Measured production cross sections of ${}^{94,95}\mathrm{Tc}$ have been compared with those produced from the $\alpha +{}^{93}\mathrm{Nb}$ reaction.

We perform viscous hydrodynamic calculations in $2+1$ dimensions to investigate the influence of bulk viscosity on the viscous suppression of elliptic flow in noncentral heavy-ion collisions at Relativistic Heavy Ion Collider energies. Bulk and shear viscous effects on the evolution of radial and elliptic flow are studied with different model assumptions for the transport coefficients. We find that the temperature dependence of the relaxation time for the bulk viscous pressure, especially its critical slowing-down near the quark-hadron phase transition at $T_c$, partially offsets effects from the strong growth of the bulk viscosity itself near $T_c$ and that even small values of the specific shear viscosity $\eta /s$ of the fireball matter can be extracted without large uncertainties from poorly controlled bulk viscous effects.

We discuss the results of calculations of the shear viscosity and thermal conductivity of pure neutron matter, carried out within the Landau-Abrikosov-Khalatnikov formalism. The probability of neutron-neutron collisions in the nuclear medium has been obtained from a realistic potential, using both the correlated basis function and the $G$-matrix approach. The results of our work indicate that medium modifications of nucleon-nucleon scattering are large, their inclusion leading to a dramatic enhancement of the transport coefficients. On the other hand, the results obtained from the two theoretical schemes appear to be in fairly good agreement.

Two consecutive Coulomb excitation experiments were performed to excite the $2_1^{+}$ states of ${}^{112,116}\mathrm{Sn}$ using a ${}^{58}\mathrm{Ni}$ beam. For ${}^{112}\mathrm{Sn}$ a $B(E2\uparrow )$ value of 0.242(8) ${\mathrm{e}}^2\hspace{0.5em}{\mathrm{b}}^2$ has been determined relative to the known value of ${}^{116}\mathrm{Sn}$. The present value is more precise than previous measurements and shows a clear discrepancy from the expected parabolic dependence between the doubly magic nuclei ${}^{100}\mathrm{Sn}$ and ${}^{132}\mathrm{Sn}$. It implies that the reduced transition probabilities are not symmetric with respect to the midshell mass $A=116$.

We make use of isospin constraints to study the parametric coupling model and the properties of asymmetric nuclear matter. Besides the usual constraints for nuclear matter—the effective nucleon mass and the incompressibility at saturation density—and the neutron star constraints—maximum mass and radius—we study the properties related to the symmetry energy. These properties constrain the parameters of the model to a small range. We apply our results to study thermodynamic instabilities in the liquid-gas phase transition as well as neutron star configurations.

We present results on two-particle angular correlations in $\mathrm{Cu}+\mathrm{Cu}$ and $\mathrm{Au}+\mathrm{Au}$ collisions at a center-of-mass energy per nucleon pair of 200 GeV over a broad range of pseudorapidity ($\eta$) and azimuthal angle ($\varphi$) values as a function of collision centrality. The PHOBOS detector at the Relativistic Heavy Ion Collider has a uniquely large angular coverage for inclusive charged particles, which allows for the study of correlations on both long- and short-range scales. A complex two-dimensional correlation structure in $\Delta \eta$ and $\Delta \varphi$ emerges, which is interpreted in the context of a cluster model. The effective cluster size and decay width are extracted from the two-particle pseudorapidity correlation functions. The effective cluster size found in semicentral $\mathrm{Cu}+\mathrm{Cu}$ and $\mathrm{Au}+\mathrm{Au}$ collisions is comparable to that found in proton-proton collisions but a nontrivial decrease in size with increasing centrality is observed. Moreover, a comparison of results from $\mathrm{Cu}+\mathrm{Cu}$ versus $\mathrm{Au}+\mathrm{Au}$ collisions shows an interesting scaling of the effective cluster size with the measured fraction of total cross section (which is related to the ratio of the impact parameter to the nuclear radius, $b/2R$), suggesting a geometric origin. Further analysis for pairs from restricted azimuthal regions shows that the effective cluster size at $\Delta \varphi ~{180}^{°}$ drops more rapidly toward central collisions than the size at $\Delta \varphi ~0^{°}$. The effect of limited $\eta$ acceptance on the cluster parameters is also addressed, and a correction is applied to present cluster parameters for full $\eta$ coverage, leading to much larger effective cluster sizes and widths than previously noted in the literature. These results should provide insight into the hot and dense medium created in heavy ion collisions.

Neutrino emission resulting from the pair breaking and formation processes in the bulk triplet superfluid in neutron stars is investigated taking into account anomalous weak interactions. I consider the problem in the BCS approximation discarding Fermi-liquid effects. By this approach I derive self-consistent equations for anomalous vector and axial-vector vertices of weak interactions taking into account ${}^3{P}_2$-${}^3{F}_2$ mixing. Further, I simplify the problem and consider pure ${}^3{P}_2$ pairing with $m_j=0$, as is adopted in the minimal-cooling paradigm. As was expected because of current conservation, I have obtained a large suppression of neutrino emissivity in the vector channel. More exactly, the neutrino emission through the vector channel vanishes in the nonrelativistic limit $V_F=0$. The axial channel is also found to be moderately suppressed. Total neutrino emissivity is suppressed by a factor of $1.9\times {10}^{-1}$ relative to original estimates using bare weak vertices.

We study proton-rich nucleosynthesis in windlike outflows from $\gamma$-ray bursts accretion disks with the aim of determining if such outflows are a site of the $\nu p$ process. The efficacy of this $\nu p$ process depends on thermodynamic and hydrodynamic factors. We discuss the importance of the entropy of the material, the outflow rate, the initial ejection point, and accretion rate of the disk. In some cases, the $\nu p$ process pushes the nucleosynthesis out to $A~100$ and produces light $p$ nuclei. However, even when these nuclei are not produced, neutrino-induced interactions can significantly alter the abundance pattern and cannot be neglected.

We derive density-dependent corrections to the in-medium nucleon-nucleon interaction from the leading-order chiral three-nucleon force. To this order there are six distinct one-loop diagrams contributing to the in-medium nucleon-nucleon scattering $T$ matrix. Analytic expressions are presented for each of these in both isospin-symmetric nuclear matter and nuclear matter with a small isospin asymmetry. The results are combined with the low-momentum nucleon-nucleon potential $V_{\mathrm{low}\hspace{0.5em}k}$ to obtain an effective density-dependent interaction suitable for nuclear structure calculations. The in-medium interaction is decomposed into partial waves up to orbital angular momentum $L=2$. Our results should be particularly useful in calculations where an exact treatment of the chiral three-nucleon force would otherwise be computationally prohibitive.

A new procedure is presented that combines well-known nuclear models with image reconstruction techniques. A color-coded image is built by taking the differences between measured masses and the predictions given by the different theoretical models. This image is viewed as part of a larger array in the ($N,Z$) plane, where unknown nuclear masses are hidden, covered by a “mask.” We apply a suitably adapted deconvolution algorithm, used in astronomical observations, to “open the window” and see the rest of the pattern. We show that it is possible to improve significantly mass predictions in regions not too far from measured nuclear masses.

Below-barrier no-capture breakup measurements of the weakly bound ${}^9\mathrm{Be}$ nucleus, incident on targets ranging in atomic number from 62 to 83, have been carried out using a large-area high-resolution back-angle detector array. It is shown that the three-body reconstructed reaction $Q$-value and relative energy of the breakup fragments together reveal the full dynamics of the breakup mechanism, identifying all physical processes that lead to the breakup of the projectile-like nucleus. Contrasting with the simple expectation of direct breakup into the most energetically favored clusters, the data show that breakup following $n$-transfer dominates the total breakup yield. Breakup from long-lived states in the projectile-like nucleus, which on the reaction time scale may be considered stable, has been isolated from the prompt breakup yield. It has been shown that the prompt breakup probability essentially depends on the surface separation of the interacting nuclei. The measured prompt breakup probability functions for each target have been used together with a classical trajectory model to predict the above-barrier suppression of complete fusion. The suppression factor, expressed as the fraction of incomplete fusion, is nearly independent of target charge.

We study the ${}^1{S}_0$ superfluidity of $\Lambda$ hyperons in neutron star matter and neutron stars. We use the relativistic mean field (RMF) theory to calculate the properties of neutron star matter. In the RMF approach, the meson-hyperon couplings are constrained by reasonable hyperon potentials that include the updated information from recent developments in hypernuclear physics. To examine the ${}^1{S}_0$ pairing gap of $\Lambda$ hyperons, we employ several $\Lambda \Lambda$ interactions based on the Nijmegen models and used in double-$\Lambda$ hypernuclei studies. It is found that the maximal pairing gap obtained is a few tenths of a MeV. The magnitude and the density region of the pairing gap are dependent on the $\Lambda \Lambda$ interaction and the treatment of neutron star matter. We calculate neutron star properties and find that whether the ${}^1{S}_0$ superfluidity of $\Lambda$ hyperons exists in the core of neutron stars mainly depends on the $\Lambda \Lambda$ interaction used.

We present results from ab initio no-core full configuration simulations of the exotic proton-rich nucleus ${}^{14}\mathrm{F}$, whose first experimental observation is expected soon. Calculations with the JISP16 $\mathit{NN}$ interaction are performed up to the $N_{max}=8$ basis space. The binding energy is evaluated using an extrapolation technique. This technique is generalized to excitation energies, verified in calculations of ${}^6\mathrm{Li}$, and applied to ${}^{14}\mathrm{F}$ and ${}^{14}\mathrm{B}$, the ${}^{14}\mathrm{F}$ mirror, for which some data are available.

The one-proton knockout reaction ${}^9\mathrm{Be}({}^{54}\mathrm{Ti},{}^{53}\mathrm{Sc}+\gamma )X$ at 72 MeV/nucleon has been measured. The location of the first $3/2^{-}$ state at 2110(3) keV was confirmed, and new $\gamma$-ray transitions were observed at 1111(2), 1273(2), 1539(4), and 2495(5) keV. Large spectroscopic strength to excited states in ${}^{53}\mathrm{Sc}$ was found and attributed to the knockout of $\mathit{sd}$-shell protons.

Excited states in the proton-unbound odd-odd nucleus ${}^{144}\mathrm{Ho}$ have been populated using the ${}^{92}\mathrm{Mo}({}^{54}\mathrm{Fe},\mathit{pn}){}^{144}\mathrm{Ho}$ reaction and studied using the recoil-isomer-tagging technique. The alignment properties and signature splitting of the rotational band above the $I^{\pi }=(8^{+}){}^{144m}\mathrm{Ho}$ isomer have been analyzed and the isomer confirmed to have a $\pi h_{11/2}\otimes \nu h_{11/2}$ two-quasiparticle configuration. The configuration-constrained blocking method has been used to calculate the shapes of the ground and isomeric states, which are both predicted to have triaxial nuclear shapes with $\left|\gamma \right|\approx {24}^{°}$.