We investigate the possibility for a quark-antiquark pair to form a bound state at temperatures higher than the critical one ($T>T_c$), thus after deconfinement. Our main goal is to find analytical criteria constraining the existence of such mesons. Our formalism relies on a Schrödinger equation for which we study the physical consequences of using both the free energy and the internal energy as potential term, assuming a widely accepted temperature-dependent Yukawa form for the free energy and a recently proposed nonperturbative form for the screening mass. We show that using the free energy only allows for the $1S$ bottomonium to be bound above $T_c$, with a dissociation temperature around $1.5\times T_c$. The situation is very different with the internal energy, where we show that no bound states at all can exist in the deconfined phase. But, in this last case, quasibound states could be present at higher temperatures because of a positive barrier appearing in the potential.

The existence of two systematically inconsistent sets of measurements of the ${}^{24}\mathrm{Al}$ excitation energies, which are used to determine ${}^{23}\mathrm{Mg}$$+p$ resonance energies, results in a variation of a factor 5 in the thermonuclear ${}^{23}\mathrm{Mg}$$(p,\gamma$)${}^{24}\mathrm{Al}$ reaction rate at $T=0.25$ GK. The astrophysically important energies have been determined to an uncertainty of 6 keV by measuring triton spectra from the ${}^{24}\mathrm{Mg}$(${}^3\mathrm{He}$,$t)$${}^{24}\mathrm{Al}$ reaction at $E($${}^3\mathrm{He}$$)=30$ MeV, and good general agreement is found with one previous set. The present measurement of $E_x=2346(6)$ keV for what is thought to be the most important resonance is, however, in disagreement with both prior measurements of 2328(10) and 2369(4) keV, where the latter value belongs to the outlying set. The presently determined resonance energies reduce the related uncertainty in the ${}^{23}\mathrm{Mg}$$(p,\gamma$)${}^{24}\mathrm{Al}$ reaction rate by a factor of $\approx 3$, which will constrain the determination of nuclear flow out of the NeNa cycle, and production of $A⩾20$ nuclides, in explosive hydrogen burning over a temperature range $0.2<T<1.0$ GK.

The low-energy bare-nucleus cross section for ${}^{15}\mathrm{N}$$(p,\alpha )$${}^{12}\mathrm{C}$ is extracted by means of the Trojan horse method applied to the ${}^2\mathrm{H}$(${}^{15}\mathrm{N}$,$\alpha$${}^{12}\mathrm{C}$)$n$ reaction at $E_{\mathrm{beam}}=60$ MeV. For the first time we applied the modified half-off-energy-shell resonant $R$-matrix method that takes into account off-energy-shell effects and initial- and final-state interactions. In particular it has been shown that inclusion of Coulomb ${}^{15}\mathrm{N}$$\text{−}d$ scattering and off-shell effects do not affect the determination of the astrophysical factor. Also the simple plane-wave approximation used in previous analyses is justified. The results extracted via the Trojan horse method are compared to direct data in the same energy region and show very good agreement in the energy interval 70–312 keV. These results confirm the extrapolations of the $S$ factor reported in literature.

Measurements of the differential and total cross sections for the $pd\to$${}^3\mathrm{He}$$\eta$ reaction at five energies were recently reported [Phys. Rev. C 75, 014004 (2007)] and comparisons with theoretical models were made. We point out that these comparisons involved a model based on ad hoc assumptions and hence the conclusions regarding the reaction mechanism as well as the role of the higher partial waves drawn in the above work are misleading. Revised conclusions based on better model calculations are presented.

We propose new types of density-dependent contact pairing interactions which reproduce the pairing gaps in symmetric and neutron matters obtained by a microscopic treatment based on realistic nucleon nucleon interaction. These interactions are able to simulate the pairing gaps of either the bare interaction or the interaction screened by the medium polarization effects. It is shown that the medium polarization effects cannot be cast into the usual density power law function of the contact interaction and require the introduction of another isoscalar term. The BCS-BEC crossover of neutron pairs in symmetric and asymmetric nuclear matters is studied by using these contact interactions. This work shows that the bare and screened pairing interactions lead to different features of the BCS-BEC crossover in symmetric nuclear matter. For the screened pairing interaction, a two-neutron BEC state is formed in symmetric matter at $k_{\mathit{Fn}}~0.2$ fm${}^{-1}$ (neutron density ${\rho }_n/{\rho }_0~{10}^{-3}$). In contrast, the bare interaction does not form the BEC state at any neutron density.

We present an extensive overview of production cross sections and kinetic energies for the complete set of nuclides formed in the spallation of ${}^{136}\mathrm{Xe}$ by protons at the incident energy of 1 GeV per nucleon. The measurement was performed in inverse kinematics at the GSI fragment separator. Slightly below the Businaro-Gallone point, ${}^{136}\mathrm{Xe}$ is the stable nuclide with the largest neutron excess. The kinematic data and cross sections collected in this work for the full nuclide production are a general benchmark for modeling the spallation process in a neutron-rich nuclear system, where fission is characterized by predominantly mass-asymmetric splits.

Photonuclear reaction is described with an approach based on the quasideuteron nuclear photoabsorption model followed by the process of competition between light particle evaporation and fission for the excited nucleus. Thus fission process is considered as a decay mode. The evaporation-fission process of the compound nucleus is simulated in a Monte Carlo framework. Photofission reaction cross sections are analysed in a systematic manner in the energy range $~50\text{−}70$ MeV for the actinides ${}^{232}\mathrm{Th}$, ${}^{233}\mathrm{U}$, ${}^{235}\mathrm{U}$, ${}^{238}\mathrm{U}$, and ${}^{237}\mathrm{Np}$ and the pre-actinide nuclei ${}^{208}\mathrm{Pb}$ and ${}^{209}\mathrm{Bi}$. The study reproduces satisfactorily well the available experimental data of photofission cross sections at energies $~50\text{−}70$ MeV and the increasing trend of nuclear fissility with the fissility parameter $Z^2/A$ for the actinides and pre-actinides at intermediate energies ($~20\text{−}140$ MeV).

The ${\Delta }_3(L)$ statistic characterizes the fluctuations of the number of levels as a function of the length of the spectral interval. It is studied as a possible tool to indicate the regular or chaotic nature of the underlying dynamics and to detect missing levels and the mixing of sequences of levels of different symmetry, particularly in neutron resonance data. The relation between the ensemble average and the average over different fragments of a given realization of spectra is considered. A useful expression for the variance of ${\Delta }_3(L)$ that accounts for finite sample size is discussed. An analysis of neutron resonance data presents the results consistent with a maximum likelihood method applied to the level spacing distribution.

In the framework of the Glauber-Gribov field theory in the eikonal approximation, we show that in hadron-nucleus collisions in the high-energy limit and under specific conditions, the rescattering contributions to the $J/\psi$ production cross section vanish, leading to an $A^1$ dependence on the atomic number $A$-except for nuclear effects in the nucleus structure function, the so-called shadowing. We show that the data from the BNL Relativistic Heavy Ion Collider on $J/\psi$ production in $d$-Au collisions can be described with nuclear shadowing alone $({\sigma }_{\mathrm{abs}}=0$). The corresponding results for $\mathrm{Au}\text{−}\mathrm{Au}$ collisions are also presented and compared with available data.

The nuclear modification factor $R_{\mathit{AA}}$ for ${\pi }_0$ production in Au+Au collisions at $\sqrt{s}=200A$ GeV is calculated and studied at high transverse momenta $p_T$. The soft thermalized nuclear medium is described within the framework of relativistic ideal three-dimensional hydrodynamics. The energy loss of partonic jets is evaluated in the context of gluon bremsstrahlung in the thermalized partonic matter. We provide a systematic analysis of the azimuthal asymmetry of ${\pi }_0$ suppression at high $p_T$ in central and noncentral collisions at mid and forward rapidity. The determination of $R_{\mathit{AA}}$ as a function of $p_T$ at different azimuthal angles and different rapidities makes for a stringent test of our theoretical understanding of jet energy loss over a variety of in-medium path lengths, temperatures, and initial partonic jet energies. This lays the groundwork for a tomography of the nuclear medium.

We reanalyze the existence of antikaon condensation phase in neutron stars with large mass and high gravitational redshift with not only the Glendenning-Moszkowski (GM) model but also the Zimanyi-Moszkowski (ZM) model in the framework of relativistic mean field (RMF) approximation theory. We find that even in the large mass and high redshift neutron stars, there are still some stiff enough equations of state of neutron star matter so that the pure antikaon condensation phase and the mixed phase of normal baryons and antikaon condensation can exist. By comparing the result given in the GM model and that in the ZM model, we notice that the existence of antikaon condensation phase does not depend on the details of the models.

The density functional theory is extended to account for self-bound systems. To this end the Hohenberg-Kohn theorem is formulated for the intrinsic density and a Kohn-Sham-like procedure for an $N$-body system is derived using the adiabatic approximation to account for the center of mass motion.

The energy dependence of the optical potential for the elastic scattering of ${}^6\mathrm{He}$ on ${}^{209}\mathrm{Bi}$ at near and subbarrier energies is studied. Elastic angular distributions and the reaction cross section were simultaneously fitted by performing some modifications in the ECIS code. A phenomenological optical model potential with the Woods-Saxon form was used. There are signatures that the so-called breakup threshold anomaly (BTA) is present in this system having a halo projectile ${}^6\mathrm{He}$, as it had been found earlier for systems involving stable weakly bound nuclei.

The odd-odd nucleus ${}^{210}\mathrm{Bi}$ is studied within the framework of the shell model using effective two-body matrix elements derived from the CD-Bonn nucleon-nucleon potential. The experimental energies of the proton-neutron multiplet $\pi h_{9/2}\nu g_{9/2}$ are remarkably well reproduced by the theory, which accounts for the $1^{-}$ state being the ground state instead of the $0^{-}$ predicted by the Nordheim strong coupling rule. It is shown that the core-polarization effects are crucial to produce this inversion. The similarity between proton-neutron multiplets in the ${}^{132}\mathrm{Sn}$ and ${}^{208}\mathrm{Pb}$ regions is discussed in connection with the effective interaction.

A model that takes into account the Landau-Zener promotion mechanism during fission was developed recently. The structures observed in the subthreshold neutron-induced fission of ${}^{232}\mathrm{Th}$ are investigated employing this model. Theoretical single-particle excitations of a phenomenological two-humped barrier are determined by solving a system of coupled differential equations for the motion along the optimal fission path. A rather good agreement with experimental data is obtained using a small number of independent parameters. It is predicted that the structure at 1.4 and 1.6 MeV is mainly dominated by a spin 3/2 partial cross section with a small admixture of spin 1/2, while the structure at 1.7 MeV is given by a large partial cross section of spin 5/2.

The mass spectra of strange baryons in the octet family are investigated in a finite-energy QCD sum rule approach based on the Gauss-Weierstrass transform. The phenomenological form of the spectral function is saturated by the ground state and two of the lowest excited states, considered as having opposite parities. Treating the ground-state parameters as known quantities, the masses, widths, and couplings to the interpolating fields are determined and compared with experiment.

We discuss an asymmetry of the decay $\omega \to e^{+}{e}^{-}$ in nuclear matter with respect to the electron and positron energies. This asymmetry is sensitive to the properties of the ω meson self-energy and, in particular, it has a nontrivial dependence on the ω energy and momentum. Therefore, this asymmetry may serve as a powerful tool in studying the properties of the ω meson in the nuclear medium.

The properties and composition of the outer crust of nonaccreting cold neutron stars are studied by applying the model of Baym, Pethick, and Sutherland (BPS) and taking into account for the first time triaxial deformations of nuclei. Two theoretical nuclear models, Hartree-Fock plus pairing in the BCS approximation (HF-BCS) with Skyrme SLy6 parametrization and Hartree-Fock-Bogolyubov (HFB) with Gogny D1S force, are used to calculate the nuclear masses. The two theoretical calculations are compared; points of comparison of the two calculations include their neutron drip lines, binding energies, magic neutron numbers, and the sequence of nuclei in the outer crust of nonaccreting cold neutron stars, with special emphasis on the effect of triaxial deformations. The BPS model is extended by higher-order corrections for the atomic binding, screening, exchange, and zero-point energies. The influence of the higher-order corrections on the sequence of the outer crust is investigated.

Isotope temperatures from double ratios of hydrogen, helium, lithium, beryllium, and carbon isotopic yields, and excited-state temperatures from yield ratios of particle-unstable resonances in ${}^4\mathrm{He}$, ${}^5\mathrm{Li}$, and ${}^8\mathrm{Be}$, were determined for spectator fragmentation, following collisions of ${}^{197}\mathrm{Au}$ with targets ranging from C to Au at incident energies of 600 and 1000 MeV per nucleon. A deviation of the isotopic from the excited-state temperatures is observed which coincides with the transition from residue formation to multi-fragment production, suggesting a chemical freeze-out prior to thermal freeze-out in bulk disintegrations.