A new framework for evaluating hydrodynamic models of relativistic heavy ion collisions has been developed. This framework, a comprehensive heavy ion model evaluation and reporting algorithm (CHIMERA) has been implemented by augmenting UVH 2+1D viscous hydrodynamic model with eccentricity fluctuations, pre-equilibrium flow, and the ultrarelativistic quantum molecular dynamic (UrQMD) hadronic cascade. A range of initial temperatures and shear viscosity to entropy ratios were evaluated for four initial profiles, $N_{\mathrm{part}}$ and $N_{\mathrm{coll}}$ scaling with and without pre-equilibrium flow. The model results were compared to pion spectra, elliptic flow, and femtoscopic radii from 200 GeV Au+Au collisions for the 0–20$\%$ centrality range. Two sets of initial density profiles, $N_{\mathrm{part}}$ scaling with pre-equilibrium flow and $N_{\mathrm{coll}}$ scaling without were shown to provide a consistent description of all three measurements.

By using the revised Landau hydrodynamic model and taking into account the effect of leading particles, we discuss the pseudorapidity distributions of produced charged particles in nucleus-nucleus collisions at high energy. The theoretical results are in good agreement with the experimental measurements carried out by PHOBOS Collaboration in different centrality Au+Au and Cu+Cu collisions at the maximum energy of $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$ at the BNL Relativistic Heavy Ion Collider.

Electron-capture rates at different density and temperature conditions are evaluated for a set of $pf$-shell nuclei representative of the constituents in presupernova formations. The nuclear structure part of the problem is described within a quasiparticle random-phase approximation based on a deformed Skyrme Hartree-Fock self-consistent mean field with pairing correlations and residual interactions in particle-hole and particle-particle channels. The energy distributions of the Gamow-Teller strength are evaluated and compared to benchmark shell-model calculations and experimental data extracted from charge-exchange reactions. The model dependence of the weak rates are discussed and the various sensitivities to both density and temperature are analyzed.

It is shown that the standard shell-model representation is inadequate to explain cluster decay processes due to a deficient asymptotic behavior of the corresponding single-particle wave functions. A new representation is proposed which is derived from a mean field consisting of the standard Woods-Saxon plus spin-orbit potential of the shell model, with an additional attractive pocket potential of a Gaussian form localized on the nuclear surface. The eigenvectors of this new mean field provide a representation which retains all the benefits of the standard shell model while at the same time reproducing well the experimental absolute $\alpha$-decay widths from heavy nuclei.

We point out a simplicity that arises when we use an interaction in which only an energy with odd $J$ is nonzero. The emphasis is on $J=J_{\text{max}}$ and in particular $J=9^{+}$ in the $g_{9/2}$ shell. It is noted that high overlaps can be deceptive. In many cases a single set of unitary 9-$j$ coefficients gives either an exact or a surprisingly good approximation to the wave function of a nondegenerate state. The many degeneracies that occur in these calculations are discussed and explained. As a counterpoint, we compare the results with an interaction in which both the $J=0$ and $J=J_{\text{max}}$ two-body matrix elements are equal (and attractive). Comparisons with a more realistic interaction are also made.

In reference to recent experiments, the collective clusterization approach is employed to investigate the dynamics of ${}^6\mathrm{Li}+{}^{144,152}$Sm reactions over a wide range of incident energies spread across the Coulomb barrier. In order to account for the role of deformations, the cross sections for the ${}^6\mathrm{Li}+{}^{152}\mathrm{Sm}\to {}^{158}$Tb${}^{*}\to A_1+A_2$ reaction have been studied using a spherical choice of fragmentation, and by considering static ${\beta }_{2i}\left(0\right)$ and dynamic ${\beta }_{2i}\left(T\right)$ quadrupole deformations within the optimum orientations ${\theta }_i^{\mathrm{opt}}$ approach. Furthermore, the orientation degree of freedom is shown to play an important role, and the same has been investigated by considering equatorial (compact) as well as polar (noncompact) orientational features. The role of level density parameter, barrier modification, and angular momentum dependence is duly addressed. Also, the shell closure effect and the $N/Z$ dependence of decay fragments have been explored in context of the fragmentation process of ${}^{150,158}$Tb nuclei. Finally, the incomplete fusion process (ICF) observed due to break up of loosely bound projectile ${}^6$Li on the deformed target ${}^{152}$Sm is worked out.

The event-by-event fission model freya is employed to study photon observables in spontaneous fission and fission induced by thermal neutrons. Comparison with available data is made as far as possible, including some recent correlation studies.

We calculate theoretically the formation spectra of ${\eta }^{\prime }\left(958\right)$-nucleus systems in the $(p,d)$ reaction for the investigation of in-medium modification of the ${\eta }^{\prime }$ mass. We show comprehensive numerical calculations based on a simple form of the ${\eta }^{\prime }$ optical potential in nuclei with various potential depths. We conclude that one finds evidence of a possible attractive interaction between ${\eta }^{\prime }$ and the nucleus as a peak structure appearing around the ${\eta }^{\prime }$ threshold in light nuclei such as ${}^{11}$C, when the attractive potential is stronger than 100 MeV and the absorption width is of order 40 MeV or less. Spectroscopy of the $(p,d)$ reaction is expected to be performed experimentally at existing facilities, such as GSI. We also estimate the contributions from the $\omega$ and $\varphi$ mesons, which have masses close to the ${\eta }^{\prime }$ meson, concluding that the observation of the peak structure of the ${\eta }^{\prime }$-mesic nuclei is not disturbed, although their contributions may not be small.

The relativistic local density approximation (LDA) for the Coulomb exchange functional in nuclear systems is presented. This approximation is composed of the well-known Slater approximation in the nonrelativistic scheme and the corrections due to the relativistic effects. Its validity in finite nuclei is examined by comparing with the exact treatment of the Coulomb exchange term in the relativistic Hartree-Fock-Bogoliubov theory. The relativistic effects are found to be important and the exact Coulomb exchange energies can be reproduced by the relativistic LDA within $5\%$ demonstrated by the semimagic Ca, Ni, Zr, Sn, and Pb isotopes from proton drip line to neutron drip line.

The $N^{*}\left(1535\right)S_{11}$ coupling strength to the $K^{+}\Lambda$ channel, $g_{N^{*}\left(1535\right)\Lambda K^{+}}$, is extracted from the latest and largest $K^{+}\Lambda$ photoproduction database by using an isobar model. It is found that the coupling is small. In terms of the coupling ratio the best result is $R\equiv |g_{N^{*}\left(1535\right)\Lambda K^{+}}/g_{N^{*}\left(1535\right)\eta p}|=0.460\pm 0.172$, much smaller than that obtained from the isobar analysis of the $J/\psi$ decays, i.e., $1.3\pm 0.3$, but consistent with the results of the unitary chiral approach of the same decay processes as well as the partial wave analysis of kaon photoproduction, i.e., $R=0.5\sim 0.7$. The different results of $R$ found here and in the literature to date suggest that a more solid definition of the coupling constant, especially in the case of the $N^{*}\left(1535\right)S_{11}$ state, is urgently required before a fair comparison can be made.

Background: The importance-truncated no-core shell model (IT-NCSM) has recently been shown to extend theoretical nuclear structure calculations of $p$-shell nuclei to larger model ($N_{\max }$) spaces. The importance truncation procedure selects only relatively few of the many basis states present in a “large” $N_{\max }$ basis space, thus making the calculation tractable and reasonably quick to perform. Initial results indicate that the procedure agrees well with the NCSM, in which a complete basis is constructed for a given $N_{\max }$.

Purpose: An analysis of uncertainties in IT-NCSM such as those generated from the extrapolations to the complete $N_{\max }$ space have not been fully discussed. We present a method for estimating the uncertainty when extrapolating to the complete $N_{\max }$ space and demonstrate the method by comparing extrapolated IT-NCSM to full NCSM calculations up to $N_{\max }=14$. Furthermore, we study the result of extrapolating IT-NCSM ground-state energies to $N_{\max }=\infty$ and compare the results to similarly extrapolated NCSM calculations. A procedure is formulated to assign uncertainties for $N_{\max }=\infty$ extrapolations.

Method: We report on ${}^6\mathrm{Li}$ calculations performed with the IT-NCSM and compare them to full NCSM calculations. We employ the Entem and Machleidt chiral two-body next-to-next-to-next leading order (N3LO) interaction (regulated at 500 MeV/$c$), which has been modified to a phase-shift equivalent potential by the similarity renormalization group (SRG) procedure. We investigate the dependence of the procedure on the technique employed to extrapolate to the complete $N_{\max }$ space, the harmonic oscillator energy ($\hslash \Omega$), and investigate the dependence on the momentum-decoupling scale ($\lambda$) used in the SRG. We also investigate the use of one or several reference states from which the truncated basis is constructed.

Results: We find that the uncertainties generated from various extrapolating functions used to extrapolate to the complete $N_{\max }$ space increase as $N_{\max }$ increases. The extrapolation uncertainties range from a few keV for the smallest $N_{\max }$ spaces to about 50 keV for the largest $N_{\max }$ spaces. We note that the difference between extrapolated IT-NCSM and NCSM ground-state energies, however, can be as large as 100–250 keV depending on the chosen harmonic oscillator energy ($\hslash \Omega$). IT-NCSM performs equally well for various SRG momentum-decoupling scales, $\lambda =2.02$ fm${}^{-1}$ and $\lambda =1.50$ fm${}^{-1}$.

Conclusions: In the case of ${}^6$Li, when using the softened chiral nucleon-nucleon N3LO interaction, we have determined the difference between extrapolated $N_{\max }=\infty$ IT-NCSM and full NCSM calculations to be about 100–300 keV. As $\hslash \Omega$ increases, we find that the agreement with NCSM deteriorates, indicating that the procedure used to choose the basis states in IT-NCSM depends on $\hslash \Omega$. We also find that using multiple reference states leads to a better ground-state description than using only a single reference state.

Tensor effects on the $N=40$ gap evolution of $N=40$ isotones are studied by employing the Skyrme-Hartree-Fock-Bogoliubov (SHFB) and relativistic Hartree-Fock-Bogoliubov (RHFB) theories. The results with and without the inclusion of the tensor components are compared with each other. It is found that when the tensor force is included, both approaches present the same trend and qualitatively agree with the experimental one indicated by the $\beta$-decay studies, which implies an important role played by the tensor force in the gap evolution of $N=40$. Furthermore, it is shown that the gap evolution is dominated by the corresponding tensor contributions from $\pi$ and $\rho$-tensor coupling in the relativistic framework.

Event-by-event fluctuations in the initial density distributions of the fireballs created in relativistic heavy-ion collisions lead to event-by-event fluctuations of the final anisotropic flow angles, and density inhomogeneities in the initial state cause these flow angles to vary with the transverse momentum of the emitted particles. It is shown that these effects lead to characteristically different transverse momentum dependencies for anisotropic flow coefficients extracted from different experimental methods. These differences can be used to experimentally constrain flow angle fluctuations in the final state of heavy-ion collisions which, in turn, are sensitive to the initial-state density fluctuations and the shear viscosity of the expanding fireball medium.

The recently developed framework of anisotropic hydrodynamics is generalized to describe the dynamics of coupled quark and gluon fluids. The quark and gluon components of the fluids are characterized by different dynamical anisotropy parameters. The dynamical equations describing such mixtures are derived from kinetic theory, with the collisional kernel treated in the relaxation-time approximation, allowing for different relaxation times for quarks and gluons. Baryon number conservation is enforced in the quark and antiquark components of the fluid, but overall parton number nonconservation is allowed in the system. The resulting equations are solved numerically in the ($0+1$)–dimensional boost-invariant case at zero and finite baryon density.

The two-proton decay process is studied by using a simple approach within the framework of scattering theory. We assume that the decaying nucleus is in a pairing state and, therefore, the two-particle wave function on the nuclear surface corresponds to the two protons moving in time-reversed states. This allows us to sustain a simplified version of the decay where the protons are simultaneously emitted with the same energies. We thus obtain a coupled system of radial equations with outgoing boundary conditions. We use similar proton-proton interactions to solve BCS equations and to describe external two-proton dynamics. A strong dependence of the pairing gap and decay width upon the proton-proton interaction strength is revealed. The experimental half-lives of ${}^{45}$Fe and ${}^{48}$Ni are reproduced by using a realistic proton-proton interaction.

The quarkonium formation time in a quark-gluon plasma (QGP) is determined from the space-time correlator of heavy quark vector currents using the quarkonium in-medium mass and wave function obtained from heavy quark potentials extracted from the lattice QCD. It is found that the formation time of a quarkonium increases with the temperature of the QGP and diverges near its dissociation temperature. Also, the quarkonium formation time is longer if the heavy quark potential is taken to be the free energy from lattice calculations for a heavy quark pair, compared to that based on the more negative internal energy.

The PHENIX experiment has measured the production of ${\pi }^0$s in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}$ $=$ 200 GeV. The new data offer a fourfold increase in recorded luminosity, providing higher precision and a larger reach in transverse momentum, $p_T$, to 20 GeV/$c$. The production ratio of $\eta /{\pi }^0$ is $0.46\pm 0.01\left(\mathrm{stat}\right)\pm 0.05\left(\mathrm{syst}\right)$, constant with $p_T$ and collision centrality. The observed ratio is consistent with earlier measurements, as well as with the $p+p$ and $d+\mathrm{Au}$ values. ${\pi }^0$ are suppressed by a factor of 5, as in earlier findings. However, with the improved statistical precision a small but significant rise of the nuclear modification factor $R_{\mathrm{AA}}$ vs $p_T$, with a slope of 0.0106${\pm }_{0.0029}^{0.0034}$ (Gev/$c$)${}^{-1}$, is discernible in central collisions. A phenomenological extraction of the average fractional parton energy loss shows a decrease with increasing $p_T$. To study the path-length dependence of suppression, the ${\pi }^0$ yield is measured at different angles with respect to the event plane; a strong azimuthal dependence of the ${\pi }^0$ $R_{\mathrm{AA}}$ is observed. The data are compared to theoretical models of parton energy loss as a function of the path length $L$ in the medium. Models based on perturbative quantum chromodynamics are insufficient to describe the data, while a hybrid model utilizing pQCD for the hard interactions and anti-de-Sitter space/conformal field theory (AdS/CFT) for the soft interactions is consistent with the data.

We present a relativistic molecular dynamics approach based on the Nambu–Jona-Lasinio Lagrangian. We derive the relativistic time evolution equations for an expanding plasma, discuss the hadronization cross section, and explain how they act in such a scenario. We present in detail how one can transform the time evolution equation to a simulation program and apply this program to study the expansion of a plasma created in experiments at the Relativistic Heavy Ion Collider and the Large Hadron Collider. We present first results on the centrality dependence of $v_2$ and of the transverse momentum spectra of pions and kaons and discuss in detail the hadronization mechanism.

Using expansion of the three-body wave function of the $pep$ system in the initial state on hyperharmonic functions, the rate of the $p+p+e^{-}\to d+{\nu }_e$ reaction in the Sun is calculated. The results of calculation of the flux at 1 AU are compared with the results of a measurement made by the Borexino collaboration and Bahcall et al. theoretical predictions.