We perform Brueckner-Hartree-Fock calculations of hypernuclear matter at finite temperature and provide convenient analytical parametrizations of the results. We then study the properties of (proto)neutron stars containing hyperons. We find important effects of trapping and finite temperature on the structure of hyperonic stars.

We study the development of collectivity in the neutron-rich nuclei around $N=40$, where the experimental and theoretical evidence suggest a rapid shape change from the spherical to the rotational regime, in analogy to what happens at the island of inversion surrounding ${}^{31}\mathrm{Na}$. Theoretical calculations are performed within the interacting shell-model framework in a large valence space, based on a ${}^{48}\mathrm{Ca}$ core, which encompasses the full $\mathit{pf}$ shell for the protons and the $0f_{5/2}$, $1p_{3/2}$, $1p_{1/2}$, $0g_{9/2}$, and $1d_{5/2}$ orbits for the neutrons. The effective interaction is based on a G matrix obtained from a realistic nucleon-nucleon potential whose monopole part is corrected empirically to produce effective single-particle energies compatible with the experimental data. We find a good agreement between the theoretical results and the available experimental data. We predict the onset of deformation at different neutron numbers for the various isotopic chains. The maximum collectivity occurs in the chromium isotopes where the large deformation regime already starts at $N=38$. The shell evolution responsible for the observed shape changes is discussed in detail, in parallel to the situation in the $N=20$ region.

We present simple equations for a canonical-basis (Cb) formulation of the time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory. The equations are obtained from the TDHFB theory with an approximation that the pair potential is assumed to be diagonal in the Cb. The Cb formulation significantly reduces the computational cost. We apply the method to linear-response calculations for even-even light nuclei and demonstrate its capability and accuracy by comparing our results with recent calculations of the quasiparticle random-phase approximation with Skyrme functionals. We show systematic studies of $E1$ strength distributions for Ne and Mg isotopes. The evolution of the low-lying pygmy strength seems to be determined by the interplay of several factors, which include the neutron excess, the separation energy, the neutron-shell effects, the deformation, and the pairing.

The structure of proton unbound ${}^{30}\mathrm{S}$ states is important for determining the ${}^{29}\mathrm{P}$($p,\gamma$)${}^{30}\mathrm{S}$ reaction rate, which influences explosive hydrogen burning in classical novae and type I x-ray bursts. The reaction rate in this temperature regime had been previously predicted to be dominated by two low-lying, unobserved, $J^{\pi }=$ $3^{+}$ and $2^{+}$ resonances above the proton threshold in ${}^{30}\mathrm{S}$. To search for these levels, the structure of ${}^{30}\mathrm{S}$ was studied using the ${}^{32}\mathrm{S}$($p,t$)${}^{30}\mathrm{S}$ transfer reaction with a magnetic spectrograph. We have confirmed a previous detection of a state near 4700 keV, which had tentatively been assigned $J^{\pi }=3^{+}$. We have also discovered a new state at 4814(3) keV, which is a strong candidate for the other important resonance ($J^{\pi }=2^{+}$). The new ${}^{29}\mathrm{P}$($p,\gamma$)${}^{30}\mathrm{S}$ reaction rate is up to 4–20 times larger than previously determined rates over the relevant temperature range. The uncertainty in the reaction rate due to uncertainties in the resonance energies has been significantly reduced.

Excited states in the extremely neutron-deficient nucleus ${}^{180}\mathrm{Pb}$ have been identified for the first time using the JUROGAM II array in conjunction with the RITU recoil separator at the Accelerator Laboratory of the University of Jyväskylä. This study lies at the limit of what is presently achievable with in-beam spectroscopy, with an estimated cross section of only 10 nb for the ${}^{92}\mathrm{Mo}$(${}^{90}\mathrm{Zr}$,$2n$)${}^{180}\mathrm{Pb}$ reaction. A continuation of the trend observed in ${}^{182}\mathrm{Pb}$ and ${}^{184}\mathrm{Pb}$ is seen, where the prolate minimum continues to rise beyond the $N=104$ midshell with respect to the spherical ground state. Beyond-mean-field calculations are in reasonable correspondence with the trends deduced from experiment.

The precise determination of the neutron capture cross sections of ${}^{186}\mathrm{Os}$ and ${}^{187}\mathrm{Os}$ is important to define the $s$-process abundance of ${}^{187}\mathrm{Os}$ at the formation of the solar system. This quantity can be used to evaluate the radiogenic component of the abundance of ${}^{187}\mathrm{Os}$ due to the decay of the unstable ${}^{187}\mathrm{Re}$ ($t_{1/2}=41.2$ Gyr) and from this to infer the time duration of the nucleosynthesis in our galaxy (Re/Os cosmochronometer). The neutron capture cross sections of ${}^{186}\mathrm{Os}$, ${}^{187}\mathrm{Os}$, and ${}^{188}\mathrm{Os}$ have been measured at the CERN n_TOF facility from 1 eV to 1 MeV, covering the entire energy range of astrophysical interest. The measurement has been performed by time-of-flight technique using isotopically enriched samples and two ${\mathrm{C}}_6$D${}_6$ scintillation detectors for recording the prompt $\gamma$ rays emitted in the capture events. Maxwellian averaged capture cross sections have been determined for thermal energies between $\mathit{kT}=5$ and 100 keV corresponding to all possible $s$-process scenarios. The estimated uncertainties for the values at 30 keV are 4.1, 3.3, and $4.7\%$ for ${}^{186}\mathrm{Os}$, ${}^{187}\mathrm{Os}$, and ${}^{188}\mathrm{Os}$, respectively.

The inelastic neutron-scattering cross section of ${}^{187}\mathrm{Os}$ has been determined in a time-of-flight experiment at the Karlsruhe $3.7$-MV Van de Graaff accelerator. An almost monoenergetic beam of 30-keV neutrons was produced at the threshold of the ${}^7\mathrm{Li}$($p,n$)${}^7\mathrm{Be}$ reaction. Information on the inelastic channel is required for reliable calculations of the so-called stellar enhancement factor, by which the laboratory cross section of ${}^{187}\mathrm{Os}$ must be corrected in order to account for the thermal population of low-lying excited states at the temperatures of $s$-process nucleosynthesis, in particular of the important state at 9.75 keV. This correction represents a crucial step in the interpretation of the ${}^{187}\mathrm{Os}$/${}^{187}\mathrm{Re}$ pair as a cosmochronometer.

Neutron resonance analyses have been performed for the capture cross sections of ${}^{186}\mathrm{Os}$, ${}^{187}\mathrm{Os}$, and ${}^{188}\mathrm{Os}$ measured at the n_TOF facility at cern. Resonance parameters have been extracted up to 5, 3, and 8 keV, respectively, using the sammy code for a full $R$-matrix fit of the capture yields. From these results average resonance parameters were derived by a statistical analysis to provide a comprehensive experimental basis for modeling of the stellar neutron capture rates of these isotopes in terms of the Hauser-Feshbach statistical model. Consistent calculations for the capture and inelastic reaction channels are crucial for the evaluation of stellar enhancement factors to correct the Maxwellian averaged cross sections obtained from experimental data for the effect of thermally populated excited states. These factors have been calculated for the full temperature range of current scenarios of $s$-process nucleosynthesis using the combined information of the experimental data in the region of resolved resonances and in the continuum. The consequences of this analysis for the $s$-process component of the ${}^{187}\mathrm{Os}$ abundance and the related impact on the evaluation of the time duration of galactic nucleosynthesis via the Re/Os cosmochronometer are discussed.

A description of exclusive charged-pion electroproduction $(e,e^{\prime }{\pi }^{\pm })$ off nucleons at high energies is proposed. The model combines a Regge pole approach with the residual effect of nucleon resonances. The exchanges of $\pi (140)$, vector $\rho (770)$, and axial-vector $a_1(1260)$ and $b_1(1235)$ Regge trajectories are considered. The contribution of nucleon resonances is described using a dual connection between the exclusive hadronic form factors and inclusive deep inelastic structure functions. The model describes the measured longitudinal, transverse, and interference cross sections at the Thomas Jefferson Lab National Accelerator Facility (JLAB) and the Deutsches Elektronen Synchrotron. The scaling behavior of the cross sections is in agreement with JLAB and deeply virtual HERMES data. The results for a polarized beam-spin azimuthal asymmetry in $(\mathrm{e⃗},e^{\prime }{\pi }^{\pm })$ are presented. Model predictions for JLAB at $12$ GeV are given.

PHENIX has measured the $e^{+}{e}^{-}$ pair continuum in $\sqrt{s_{\mathit{NN}}}=200$ GeV $\mathrm{Au}+\mathrm{Au}$ and $p+p$ collisions over a wide range of mass and transverse momenta. The $e^{+}{e}^{-}$ yield is compared to the expectations from hadronic sources, based on PHENIX measurements. In the intermediate-mass region, between the masses of the $\varphi$ and the $J/\psi$ meson, the yield is consistent with expectations from correlated $c\mathrm{c̄}$ production, although other mechanisms are not ruled out. In the low-mass region, below the $\varphi$, the $p+p$ inclusive mass spectrum is well described by known contributions from light meson decays. In contrast, the $\mathrm{Au}+\mathrm{Au}$ minimum bias inclusive mass spectrum in this region shows an enhancement by a factor of $4.7\pm {0.4}^{\mathrm{stat}}\pm {1.5}^{\mathrm{syst}}\pm {0.9}^{\mathrm{model}}$. At low mass ($m_{\mathit{ee}}<0.3$ GeV/$c^2$) and high $p_T$ ($1<p_T<5$ GeV/$c$) an enhanced $e^{+}{e}^{-}$ pair yield is observed that is consistent with production of virtual direct photons. This excess is used to infer the yield of real direct photons. In central $\mathrm{Au}+\mathrm{Au}$ collisions, the excess of the direct photon yield over the $p+p$ is exponential in $p_T$, with inverse slope $T=221\pm {19}^{\mathrm{stat}}\pm {19}^{\mathrm{syst}}$ MeV. Hydrodynamical models with initial temperatures ranging from $T_{\mathrm{init}}\simeq 300–600$ MeV at times of $0.6–0.15$ fm/$c$ after the collision are in qualitative agreement with the direct photon data in $\mathrm{Au}+\mathrm{Au}$. For low $p_T<1$ GeV/$c$ the low-mass region shows a further significant enhancement that increases with centrality and has an inverse slope of $T\simeq 100$ MeV. Theoretical models underpredict the low-mass, low-$p_T$ enhancement.

The productions of thorium and uranium are key ingredients in $r$-process nucleo-cosmochronology. With the combination of improved nuclear and stellar data, we have made a detailed investigation of the $r$-process abundance pattern in the very metal-poor halo stars based on the classical $r$-process approach. It is found that the results are almost independent of specified simulations to observed abundances. The influence from nuclear mass uncertainties on a Th/U chronometer can approach 2 Gyr. Moreover, the ages of the metal-poor stars HE $1523-0901$, CS $31082-001$, and BD $+{17}^{°}3248$ are determined as $11.8\pm 3.7$, $13.5\pm 2.9$, and $10.9\pm 2.9$ Gyr, respectively. The results can serve as an independent check for age estimates of the Universe.

The computation of radiative energy loss in a finite-size QCD medium with dynamical constituents is a key ingredient for obtaining reliable predictions for jet quenching in ultrarelativistic heavy-ion collisions. We here present a theoretical formalism for the calculation of the first order in opacity radiative energy loss of a quark jet traveling through a finite-size dynamical QCD medium. We show that, while each individual contribution to the energy loss is infrared divergent, the divergence is naturally regulated once all diagrams are taken into account. Finite-size effects are shown to induce a nonlinear path-length dependence of the energy loss, recovering both the incoherent Gunion-Bertsch limit, as well as destructive Landau-Pomeanchuk-Migdal limit. Finally, our results suggest a remarkably simple general mapping between energy-loss expressions for static and dynamical QCD media.

Three-nucleon scattering equations with irreducible three-nucleon force are solved in momentum-space. The Coulomb interaction between the two protons is included using the method of screening and renormalization. The need for the renormalization of the scattering amplitudes is demonstrated numerically. The Coulomb and Urbana IX three-nucleon force effects on the observables of elastic proton-deuteron scattering and breakup are studied.

We construct a simple two-phase equation of state intended to resemble that of compressed baryon-rich matter and then introduce a gradient term in the compressional energy density to take account of finite-range effects in nonuniform configurations. With this model we study the interface between the two coexisting phases and obtain estimates for the associated interface tension. Subsequently, we incorporate the finite-range equation of state into ideal or viscous fluid dynamics and derive the collective dispersion relation for the mechanically unstable modes of bulk matter in the spinodal region of the thermodynamic phase diagram. Combining these results with time scales extracted from existing dynamical transport simulations, we discuss the prospects for spinodal phase separation to occur in nuclear collisions. We argue that these can be optimized by a careful tuning of the collision energy to maximize the time spent by the bulk of the system inside the mechanically unstable spinodal region of the phase diagram. Our specific numerical estimates suggest cautious optimism that this phenomenon may in fact occur, though a full dynamical simulation is needed for a detailed assessment.

Developments and applications are presented of an algebraic version of Bohr's collective model. Illustrative examples show that fully converged calculations can be performed quickly and easily for a large range of Hamiltonians. As a result, the Bohr model becomes an effective tool in the analysis of experimental data. The examples are chosen both to confirm the reliability of the algebraic collective model and to show the diversity of results that can be obtained by its use. The focus of the paper is to facilitate identification of the limitations of the Bohr model with a view to developing more realistic, computationally tractable models.

The three-dimensional wave function for a sharply cut-off Coulomb potential is analytically derived. The asymptotic form of the related scattering amplitude reveals a failure of the standard renormalization factor which is believed to be generally valid for any type of screening.

By measuring the ${}^{31}\mathrm{P}({}^3\mathrm{He},t){}^{31}\mathrm{S}$, ${}^{31}\mathrm{P}({}^3\mathrm{He},t){}^{31}\mathrm{S}{}^{*}(p){}^{30}\mathrm{P}$, and ${}^{32}\mathrm{S}(d,t){}^{31}\mathrm{S}$ reactions, the level scheme of ${}^{31}\mathrm{S}$ has been refined and extended up to $E_x=9.5$ MeV. A total of 17 new levels, and 5 tentative new levels, have been measured. In addition, 5 tentatively known levels have been confirmed. The uncertainties in the excitation energies of many known ${}^{31}\mathrm{S}$ levels have been reduced substantially. Spin constraints have been made for 8 proton-unbound levels by measuring 18 triton-proton angular correlations from the ${}^{31}\mathrm{P}({}^3\mathrm{He},t){}^{31}\mathrm{S}{}^{*}(p){}^{30}\mathrm{P}$ reaction. Finite proton-decay branching ratios (including discrimination between decays to the ground state and first two excited states of ${}^{30}\mathrm{P}$) have been measured for 38 levels, and upper limits have been set for 3 additional levels. The lowest isospin $T=3/2$ level has been observed, and candidates for the second and third $T=3/2$ levels have been identified. The new experimental information on ${}^{30}\mathrm{P}+p$ resonance parameters has been used together with data from previous measurements to calculate the thermonuclear, resonant ${}^{30}\mathrm{P}(p,\gamma ){}^{31}\mathrm{S}$ reaction rate over three orders of magnitude in temperature: $0.01<T<10$ GK. Good agreement is found with estimates based on Hauser-Feshbach statistical models over the range $0.08<T<10$ GK, but differences are found with rates previously estimated using the experimental information at hand.

The problem of how to compute accurately and efficiently the sign of the overlap between two general Hartree-Fock-Bogoliubov (HFB) wave functions is addressed. The results obtained can easily be extrapolated to the evaluation of the sign of the trace of a density operator exponential of one body operators.

We derive the space-time distribution of energy and momentum deposited by a fast parton traversing a weakly coupled quark-gluon plasma by treating the fast parton as the source of an external color field perturbing the medium. We then use our result as a source term for the linearized hydrodynamical equations of the medium. We show that the solution contains a sonic Mach cone and a dissipative wake if the parton moves at a supersonic speed.

We discuss the least-squares and linear-regression methods, which are relevant for a reliable determination of good nuclear-mass-model parameter sets and their errors. In this perspective, we define exact and inaccurate models and point out differences in using the standard error analyses for them. As an illustration, we use simple analytic models for nuclear binding energies and study the validity and errors of models’ parameters and uncertainties of its mass predictions. In particular, we show explicitly the influence of mass-number-dependent weights on uncertainties of liquid-drop global parameters.