We discuss simulations of finite temperature nuclear matter on the lattice. We introduce a new approximation to nucleon matrix determinants that is physically motivated by chiral effective theory. The method involves breaking the lattice into spatial zones and expanding the determinant in powers of the boundary hopping parameter.

Using dispersion relations good description of existing data on $\eta$ photoproduction on protons in the resonance energy region is obtained, and the contributions of the resonances $D_{13}\left(1520\right)$, $S_{11}\left(1535\right)$, $S_{11}\left(1650\right)$, $D_{15}\left(1675\right)$, $F_{15}\left(1680\right)$, $D_{13}\left(1700\right)$, $P_{11}\left(1710\right)$, $P_{13}\left(1720\right)$ to $\gamma p\to \eta p$ are found. In order to estimate model dependence of the obtained resonance characteristics, an isobar model is used for the analysis of the same data. We conclude that the results for the contributions of the resonances $D_{13}\left(1520\right)$, $S_{11}\left(1535\right)$, $S_{11}\left(1650\right)$, $F_{15}\left(1680\right)$ to corresponding multipole amplitudes are stable. With this the results for $D_{13}\left(1520\right)$ and $F_{15}\left(1680\right)$, combined with their Particle Data Group (PDG) photoexcitation helicity amplitudes, allow to find the branching ratios $\text{Br}\left[D_{13}\left(1520\right)\to \eta N\right]=\left(0.05\pm 0.02\right)\%$, $\text{Br}\left[F_{15}\left(1680\right)\to \eta N\right]=\left(0.16\pm 0.04\right)\%$ which have significantly better accuracy than the PDG data. The total Breit-Wigner width of the $S_{11}\left(1535\right)$ is model dependent. We have obtained $\Gamma \left[S_{11}\left(1520\right)\right]=142\text{MeV}$ and $195\text{MeV}$ using dispersion relations and the isobar model, respectively. The results for the $D_{15}\left(1675\right)$, $P_{11}\left(1710\right)$, $P_{13}\left(1720\right)$ obtained in two approaches are close to each other. The results for the $D_{13}\left(1700\right)$ are model dependent.

The self-consistent cranked harmonic oscillator with volume conservation is examined more closely. Contrary to previous claims, bifurcations corresponding to tilted rotation are found to exist, even in systems with axially symmetric ground states. The tilted angular-momentum vector is proven to always lie in a principal plane of the ellipsoidal potential. The case of ${}^{20}\mathrm{Ne}$ is used for illustrative purposes. Detailed graphical results are provided for the properties of the bifurcating trajectories, which are found with the aid of the cranked bifurcation theorem discussed in a previous publication.

The problem of eliminating the statistical fluctuations and extracting the event dynamics from event-by-event analysis is discussed. New moments $G_p$ (for continuous distribution) and $G_{q,p}$ (for anomalous distribution) are proposed, which are experimentally measurable and can eliminate the Poissonian-type statistical fluctuations to recover the dynamical moments $C_p$ and $C_{q,p}$. In this way, the dynamical distribution of the event-averaged transverse momentum ${\overline{p}}_{\mathrm{t}}$ can be extracted, and the anomalous scaling of dynamical distribution, if it exists, can be recovered, through event-by-event analysis of experimental data.

Recent measurements of the ${\pi }^{+}{\pi }^{-}$ invariant-mass distribution at RHIC show a shifted peak for the $\rho$ meson in $100A\text{GeV}$ in peripheral $\text{Au}+\text{Au}$ and even in $p+p$ collisions. A recent theoretical study based on a picture of in-medium production rates of pions showed that a large shift could result from a combination of the Boltzmann factor and the collisional broadening of the $\rho$. Here we argue that the two-pion density of states is the appropriate quantity if one assumes a sudden breakup of the system. Methods for calculating the density of states which include Bose effects are derived. The resulting invariant-mass distributions are significantly enhanced at lower masses and the $\rho$ peak is shifted downward by $\sim 35\text{MeV}$.

High spin states in ${}^{158}\mathrm{Dy}$ have been investigated using in-beam $\gamma$-ray spectroscopy techniques with the ${}^{150}\mathrm{Nd}({}^{12}\mathrm{C},4n)$ reaction. Six rotational bands and several interband transitions have been observed. Sidebands have been discussed in terms of quasiparticle configurations.

Excited $0^{+}$ states are studied in the framework of the projected shell model, aiming at understanding the nature of these states in deformed nuclei in general, and the recently observed 13 excited $0^{+}$ states in ${}^{158}\mathrm{Gd}$, in particular. The model, which contains projected two- and four-quasiparticle states as building blocks in the basis, is able to reproduce reasonably well the energies for all the observed $0^{+}$ states. The obtained $B\left(E2\right)$ values, however, tend to suggest that these $0^{+}$ states might have a mixed nature of quasiparticle excitations coupled to collective vibrations.

We explore the effects of Coulomb interaction upon the nuclear liquid vapor phase transition. Because large nuclei $\left(A>30\right)$ are metastable objects, phases, phase coexistence, and phase transitions cannot be defined with any generality and the analogy to liquid vapor is ill posed for these heavy systems. However, it is possible to account for the Coulomb interaction in the decay rates and obtain the coexistence phase diagram for the corresponding uncharged system.

We calculate the cross section for the x-ray induced accelerated decay process of the isomer ${}^{178}\mathrm{Hf}^{m2}\left({16}^{+},2.446\text{MeV},31\text{yr}\right)$ via an unknown nuclear state (including the case of a “mixed-$K$” state) hypothesized to lie about $10\text{keV}$ in energy above the isomer. The excitation of the 31 yr isomer to an intermediate level is assumed to proceed via an electronic transition between atomic shells as has been recently postulated to explain the observation of “triggering” of the decay of the isomer by irradiation with x rays. The accelerated decay cross section is calculated in the most favorable case to be $\sim {10}^{-32}{\text{cm}}^2$, a value many orders of magnitude below that needed to explain the results of the isomeric triggering experiments.

The Gamow-Teller (GT) states in ${}^{58}\mathrm{Cu}$ have been studied via the ${}^{58}\mathrm{Ni}\left({}^3\mathrm{He},t+p\right)$ and ${}^{58}\mathrm{Ni}\left({}^3\mathrm{He},t+\gamma \right)$ coincidence experiments. The GT states in ${}^{58}\mathrm{Cu}$ at $E_x=6–12\text{MeV}$, where both $T=1$ and $T=2,1^{+}$ states exist, are excited strongly in the ${}^{58}\mathrm{Ni}\left({}^3\mathrm{He},t\right)$ reaction at $E\left({}^3\mathrm{He}\right)=450\text{MeV}$ and $\theta =0°$. Proton emissions from the GT states in ${}^{58}\mathrm{Cu}$ to the hole states in ${}^{57}\mathrm{Ni}$ have been observed with solid-state detectors in coincidence with high energy tritons measured with a magnetic spectrometer. For the first time, the $\gamma$-ray emissions from the excited states in ${}^{58}\mathrm{Cu}$ and in ${}^{57}\mathrm{Ni}$, following the ${}^{58}\mathrm{Ni}\left({}^3\mathrm{He},t+p\right)$ reaction at intermediate energies, have also been observed in coincidence with tritons. Strengths of proton decay into several neutron-hole states in ${}^{57}\mathrm{Ni}$ and $\gamma$-decay strengths are used to discuss the wave functions of the GT states in ${}^{58}\mathrm{Cu}$. The $T=1$ and $T=2$ GT states do only weakly decay into a $T=3∕2,f_{7∕2}^{-1}$ neutron-hole state at $5.230\text{MeV}$ in ${}^{57}\mathrm{Ni}$, which is strongly excited via the ${}^{58}\mathrm{Ni}\left(p,d\right){}^{57}\mathrm{Ni}$ reaction. The wave functions of the $T=1$ and $T=2$ GT states with the $f_{7∕2}^{-1}$ neutron-hole configuration are inferred to be strongly coupled to $2p\text{−}2h$ configurations, making fragmented GT strengths in ${}^{58}\mathrm{Cu}$.

A $K$-matrix formalism is used to relate the amplitudes for the three reactions $pd\to {}^3\mathrm{He}\eta$, ${\pi }^{+}{}^3\mathrm{H}\to {}^3\mathrm{He}\eta$, and $pd\to {}^3\mathrm{H}{\pi }^{+}$. Free parameters are fitted to the available experimental data and an extrapolation below the $\eta {}^3\mathrm{He}$ threshold is made to see the origin of the $\eta {}^3\mathrm{He}$ threshold enhancement. The existence of a virtual—and not a quasibound—state finds support in the data. The $K$ matrix permits a discussion of $\eta \text{−}\pi$ mixing. A mixing parameter of $0.010\left(5\right)$, i.e., a mixing angle $\theta =0.6\left(3\right)°$, is extracted from a best fit to the very recent $pd\to {}^3\mathrm{He}{\pi }^0$ reaction data.

We study, within the statistical hadronization model, the influence of narrow strangeness carrying baryon resonances (pentaquarks) on the understanding of particle production in relativistic heavy ion collisions. There is a great variation of expected yields as a function of heavy ion collision energy due to rapidly evolving chemical conditions at particle chemical freeze-out. At relatively low collision energies, these new states lead to improvement of statistical hadronization fits.

A general formalism is established for constructing models for the photoproduction of mesons from the nucleon. The essential ingredient is a mass operator which describes the coupling between meson-baryon, photon-baryon, and single-baryon channels. The most general forms for the mass operator interactions which produce these couplings are derived. These forms also provide generalizations of the Chew-Goldberger-Low-Nambu amplitudes for pion-nucleon photoproduction to any meson-baryon final state. The models lead to $S$-matrix elements that transform properly under inhomogeneous Lorentz transformations and are gauge invariant. The photoproduction amplitudes include final state interactions and satisfy Watson’s theorem. A specific model is constructed by deriving the mass operator interactions from effective Lagrangians that describe the couplings of mesons, photons, and baryons. The electromagnetic interactions include direct and crossed nucleon contributions, as well as direct contributions from the $P_{33}\left(1232\right)$, $P_{11}\left(1440\right)$, $D_{13}\left(1520\right)$, and $S_{11}\left(1535\right)$ resonances. A contact term and exchange terms due to the $\pi$, $\rho$, and $\omega$ mesons are also included. The model gives a good fit to the significant multipoles in the energy range from the single-pion, photoproduction threshold up to a center-of-momentum energy of $W=1550\text{MeV}$, which corresponds to a photon lab energy of $810\text{MeV}$.

The usefulness of the three-body mechanism of $\eta$-meson production is tested by extending to high energies a recently developed two-step model of the $pd\to {}^3\mathrm{He}\eta$ reaction by us, which was successful in reproducing the energy dependence of the data near threshold. The $\eta$ production in this model proceeds in two steps via the $pp\to \pi d$ and $\pi N\to \eta p$ reactions with the intermediate particles being off-shell. The final state interaction is incorporated through a $T$ matrix for $\eta {}^3\mathrm{He}$ elastic scattering constructed using few body equations. In a comparison of the calculated angular distributions with some recently available data, we discover the limitations of the model at high energies.

We discuss the mechanisms that lead to $\Lambda \left(1405\right)$ production in the ${\pi }^{-}p\to K^0\pi \Sigma$ reaction. The problem has gained renewed interest after different works converge to the conclusion that there are two resonances around the region of $1400\text{MeV}$, rather than one, and that they couple differently to the $\pi \Sigma$ and $\overline{K}N$ channels. We look at the dynamics of that reaction and find two mechanisms which eventually filter each one of the resonances, leading to very different shapes of the $\pi \Sigma$ invariant mass distributions. The combination of the two mechanisms leads to a shape of this distribution compatible with the experimental measurements.

The ${}^{14}\mathrm{N}\left(\vec{p},\gamma \right){}^{15}\mathrm{O}$ reaction has been investigated by measuring the angular distributions of its cross section and analyzing power using a $270\text{−}\text{keV}$ polarized proton beam. Calculations using a direct-capture-plus-resonance model were compared with the data. The results indicate the presence of $\gamma$ transition amplitudes which were not considered in previous extrapolations of the astrophysical $S$ factor to low energies. The impact on the zero-energy $S$ factor of the ${}^{14}\mathrm{N}\left(\vec{p},\gamma \right){}^{15}\mathrm{O}$ reaction is discussed.

$\overline{K}N$ interactions are investigated via an effective nonlinear chiral meson-baryon Lagrangian. The adjustable parameters are determined by a fitting procedure on the $K^{-}p$ threshold branching ratios and total cross-section data for $p_K^{lab}⩽250\text{MeV}∕c$. We produce predictions for the $\Sigma \pi$ mass spectrum, and scattering lengths $a_{K^{-}p}$, $a_n(K^{-}n\to K^{-}n)$, $a_n^{\circ }({\overline{K}}^{\circ }n\to {\overline{K}}^{\circ }n)$, and $a_{ex}(K^{-}p\to {\overline{K}}^{\circ }n)$. The $\overline{K}N$ amplitudes thus obtained, as well as those for other two-body channels ($\pi N$, $NN$, and $YN$), are used as input to predict the scattering length $A_{K^{-}d}$, for which we have devised a relativistic version of the three-body Faddeev equations. Results for all two- and three-body coupled channels are reported both in isospin and particle bases. All available $\overline{K}N$ data are well reproduced and our best results for the $K^{-}p$ and $K^{-}d$ scattering lengths are $a_{K^{-}p}=(-0.90+i0.87)$ fm and $A_{K^{-}d}=(-1.80+i1.55)$ fm.

The level densities and radiative strength functions (RSFs) in ${}^{160,161}\mathrm{Dy}$ have been extracted using the $\left({}^3\mathrm{He},\alpha \gamma \right)$ and $({}^3\mathrm{He},{{}^3\mathrm{He}}^{\prime }\gamma )$ reactions, respectively. The data are compared to previous measurements on ${}^{161,162}\mathrm{Dy}$. The energy distribution in the canonical ensemble is discussed with respect to the nucleon Cooper pair breaking process. The gross properties of the RSF are described by the giant electric dipole resonance. The RSF at low $\gamma$-ray energies is discussed with respect to temperature dependency. Resonance parameters of a soft dipole resonance at $E_{\gamma }\sim 3\text{MeV}$ are deduced.

The symmetry energy for nuclear matter and its relation to the neutron skin in finite nuclei is discussed. The symmetry energy as a function of density obtained in a self-consistent Green function approach is presented and compared to the results of other recent theoretical approaches. A partial explanation of the linear relation between the symmetry energy and the neutron skin is proposed. The potential of several experimental methods to extract the neutron skin is examined.