We calculate the impact of the complete set of two-pion exchange contributions at chiral fourth order (also known as next-to-next-to-next-to-leading order) on peripheral partial waves of nucleon-nucleon scattering. Our calculations are based upon the analytical studies by Kaiser. It turns out that the contribution of fourth order is substantially smaller than the one of third order, indicating convergence of the chiral expansion. We compare the prediction from chiral pion exchange with the corresponding one from conventional meson theory as represented by the Bonn full model and find, in general, good agreement. Our calculations provide a sound basis for investigating the issue whether the low-energy constants determined from $\pi N$ lead to reasonable predictions for $\mathrm{NN}.\mathrm{}$

The energy levels, electromagnetic properties as well as the β-decay ratios are studied in the odd-mass isotopes of Rh and Pd in the neutron-proton interacting boson-fermion model.

Excited states of ${}^{162}\mathrm{Er}$ were populated in β decay and studied through γ-ray spectroscopy at TRIUMF ISAC to assess the nature of low-lying $K^{\pi }{=0\mathrm{}}^{+}$ instrinsic excitations. Improved measurements of the decay properties of the lowest $K^{\pi }{=0\mathrm{}}^{+}$ excitation suggest a β-vibrational nature for its structure. Data were also obtained ruling out the spin assignment of a previously assigned $K^{\pi }{=(0\mathrm{}}_3^{+})$ excitation.

We present differential cross sections and complete sets of polarization-transfer coefficients, $D_{\mathrm{ij}},$ obtained in the ${}^{13}\mathrm{C}(\overrightarrow{p},\overrightarrow{n}{)}^{13}\mathrm{N}$ reaction studied at 197 MeV incident proton energy and laboratory angles between $0°$ and $33°.$ These complete sets of polarization observables are used to obtain spin-longitudinal and spin-transverse components for transitions to the ground state, to the first, and to the unresolved second and third excited states in ${}^{13}\mathrm{N}$ at 2.36 MeV and $\mathrm{}(3.50+3.55)\mathrm{}\hspace{0.5em}\mathrm{MeV},$ respectively. The results are used to obtain the two $\Delta J^{\pi }$ contributions for the ground and first excited state transitions and are compared with corresponding distorted-wave impulse approximation (DWIA) calculations. In particular, empirical angular distribution values for the unique spin-longitudinal $\Delta {J=0\mathrm{}}^{-}$ transition to the first excited state in ${}^{13}\mathrm{N}$ are obtained and compared with DWIA calculations.

Binary decay excitation functions have been measured for the ${}^{16}\mathrm{O}{+}^{10}\mathrm{B}$ system at 22 MeV $<E_{\mathrm{c}.\mathrm{m}.\mathrm{}}<24.5\mathrm{}\hspace{0.5em}\mathrm{MeV}$ $\left(\delta E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\sim 20\hspace{0.5em}\mathrm{keV}\right)$ and 17 $\mathrm{MeV}<E_{\mathrm{c}.\mathrm{m}.\mathrm{}}<25\mathrm{}\hspace{0.5em}\mathrm{MeV}$ $\left(\delta E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\sim 190\hspace{0.5em}\mathrm{keV}\right)$ and for the ${}^{19}\mathrm{F}{+}^{12}\mathrm{C}$ system at 22 $\mathrm{MeV}<E_{\mathrm{c}.\mathrm{m}.\mathrm{}}<24.5\mathrm{}\hspace{0.5em}\mathrm{MeV}$ $\left(\delta E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\sim 20\hspace{0.5em}\mathrm{keV}\right).\mathrm{}$ The binary fragments were identified by the kinematic coincidence technique. The excitation functions for these systems show strong fluctuations and average decay widths were obtained through the analysis of energy correlation functions. The small widths observed for the ${}^{16}\mathrm{O}{+}^{10}\mathrm{B}$ (about 20 keV) and ${}^{19}\mathrm{F}{+}^{12}\mathrm{C}$ (about 40 keV) systems show a constant behavior with the fragments’ excitation energy and scattering angle. These widths correspond to an intermediate system time scale of about $2\times {10}^{-20}\hspace{0.5em}\mathrm{s},$ which is larger than its revolution time. These features suggest the presence of the fusion-fission mechanism, where the compound nucleus takes a long time to acquire a relaxed shape and thermal equilibrium. For the ${}^{16}\mathrm{O}{+}^{10}\mathrm{B}$ system, larger widths (about 350 keV) were also observed, which are related to a faster process. These widths show a clear dependence with the scattering angle in the elastic scattering channel. These aspects are expected for a process where the time scale is comparable to the intermediate system revolution time, like an orbiting mechanism. Theoretical predictions for fusion-fission and orbiting mechanisms were compared to the experimental results and a good agreement was observed.

Intermediate mass fragments (IMFS) (IMF: $3<~Z_{\mathrm{IMF}}<~20)$ observed in coincidence with two correlated fission fragments following incomplete fusion in ${}^{12}\mathrm{C}{+}^{232}\mathrm{Th}$ at $E/A=16\mathrm{}$ and 22 MeV are investigated. IMFs emitted prior to significant deformation of the fissioning system, as well as IMFs emitted near scission, are distinguished based upon their characteristic kinetic energy and angular distributions. The yield distributions of IMFs emitted near scission in ${\mathrm{these}}^{12}\mathrm{C}$ induced reactions are compared with near-scission IMF yields in spontaneous and low-energy ternary fission. Comparisons are made to both experimental fusion-evaporation data and theoretical predictions of a statistical model. The excitation energy dependence of relative IMF yields for both isotropic and near-scission emission is also presented. Our results for near-scission emission suggest that the production of IMFs near scission is inconsistent with a statistical emission mechanism in which emission barriers follow a standard Z dependence. Dynamical model calculations are used to investigate the role of dissipation, angular momentum, $N/Z,$ and kinetic energy on the fragment formation near scission.

Total charge-changing cross sections and cross sections for the production of B and Be fragments were directly measured for reactions induced by $\sim 110–250\hspace{0.5em}\mathrm{M}\mathrm{e}\mathrm{V}/\mathrm{n}\mathrm{u}\mathrm{c}\mathrm{l}\mathrm{e}\mathrm{o}\mathrm{n}{\hspace{0.5em}}^{12}\mathrm{C}$ ions in C, ${\mathrm{CH}}_2,$ and ${\mathrm{H}}_2\mathrm{O}$ targets. Etched track detector (CR-3) was used, together with an automatic track measuring system and a track matching algorithm, to count and to identify the primary and secondary particles. A comparison of the present data and of previously measured cross sections with model predictions is carried out. For the total charge-changing cross section, a model developed at NASA gives the best agreement with the present results (about 3% on the average). However, for the production of fragments, the results of models deviate on average for all systems studied by 9–58 % from the data presented in this work for $Z=5\mathrm{}$ and by 5–47 % for $Z=4.\mathrm{}$ The model known as NUCFRG2 is the most reliable in giving the closest values for fragmentation cross sections, 9 and 5% for B and Be fragments, respectively, for the systems studied in this work.

Extensive systematizations of theoretical and experimental nuclear densities and of optical potential strengths extracted from heavy-ion elastic scattering data analyses at low and intermediate energies are presented. The energy dependence of the nuclear potential is accounted for within a model based on the nonlocal nature of the interaction. The systematics indicates that the heavy-ion nuclear potential can be described in a simple global way through a double-folding shape, which basically depends only on the density of nucleons of the partners in the collision. The possibility of extracting information about the nucleon-nucleon interaction from the heavy-ion potential is investigated.

The total deuteron reaction cross sections for several targets are calculated at deuteron energies from 38 to 97 MeV. Single-nucleon knockout and deuteron photodisintegration are considered explicitly as the absorptive channels. The photodisintegration contribution to the absorption is obtained using a Glauber prescription. Corrections due to Pauli blocking are included in the total nucleon-nucleon cross section. The WKB imaginary phase shift is used with refractive effects taken into account. WKB results differ significantly from the usual Glauber-eikonal ones for heavy nuclei at low energy. Pauli blocking and refractive effects are smaller at higher energies. Spatial correlations are also considered and increase the total reaction cross section.

We construct the formula for the photonuclear total absorption cross section using the projection method and the unitarity relation. Our treatment is very effective when interference effects in the absorption processes on a nucleon are strong. The disappearance of the peak around the position of the $D_{13}$ resonance in the nuclear photoabsorption can be explained with the cooperative effect of the interference in two-pion production processes, the Fermi motion, the collision broadenings of $\Delta$ and $N^{*},$ and the pion distortion in the nuclear medium. The change of the interference effect by the medium plays an important role.

Event-by-event fluctuations of hadronic patterns in heavy-ion collisions are studied in search of signatures of quark-hadron phase transition. Attention is focused on a narrow strip in the azimuthal angle with small $\Delta y.\mathrm{}$ The fluctuations in the gaps between particles are quantified by simple measures. A scaling exponent $\alpha$ is shown to exist around $T_c.$ An index $\xi$ is shown to characterize the critical fluctuation; it is a numerical constant $\xi =0.05\mathrm{}\pm \mathrm{0.01.}$ All the measures considered in this gap analysis are experimentally observable. Whether or not the theoretical predictions, based on simulations using a two-dimensional Ising model, are realistic for heavy-ion collisions, analysis of the experimental data suggested here should be carried out, since the existence of a scaling behavior is of interest in its own right.

The directed flow of particles produced in ultrarelativistic heavy ion collisions at the CERN Super Proton Synchrotron and the Brookhaven Relativistic Heavy Ion Collider is so small that currently available methods of analysis are at the border of applicability. Standard two-particle and flow-vector methods are biased by large nonflow correlations. On the other hand, cumulants of four-particle correlations, which are free from this bias, are plagued by large statistical errors. Here, we present a new method based on three-particle correlations, which uses the property that elliptic flow is large at these energies. This method may also be useful at intermediate energies, near the balance energy where directed flow vanishes.

Yields of hadrons, their average masses, and energies per hadron at the stage of chemical freeze-out in (ultra)relativistic heavy-ion collisions are analyzed within the statistical model. The violation of the scaling $〈E〉/〈N〉\cong 1\hspace{0.5em}\mathrm{GeV}$ observed in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s}=130A\hspace{0.5em}\mathrm{GeV}$ is linked to the formation of resonance-rich matter with a considerable fraction of baryons and antibaryons. The rise of the energy-per-hadron ratio in baryon-dominated matter is discussed. A violation of the scaling condition is predicted for a very central zone of heavy-ion collisions at energies around $40A\hspace{0.5em}\mathrm{GeV}.$

We apply the effective Lagrangian approach to investigate the role of the nucleon resonances in $\omega$-meson photoproduction at energies near the threshold. The nonresonant amplitudes are taken from the previous investigations at higher energies and consist of the pseudoscalar meson exchange and the nucleon Born terms. The resonant amplitudes are calculated from effective Lagrangians with the $N^{*}\to \gamma N$ and $N^{*}\to \omega N$ coupling constants fixed by the empirical helicity amplitudes and the vector meson dominance model. The contributions from the nucleon resonances are found to be significant in changing the differential cross sections in a wide interval of t and various spin observables. In particular, we suggest that a crucial test of our predictions can be made by measuring single and double spin asymmetries.

Cross sections of $\mathrm{baryon}+\mathrm{baryon}\to (\Omega \Omega {)}_{J^{\pi }{=0\mathrm{}}^{+}}+X$ are studied using an effective Hamiltonian method. For low energy region, the γ production process dominates; its cross sections are of order of $0.3–1.6\hspace{0.5em}\mu \mathrm{b}$ for $p_{\Omega }=100\mathrm{}–400\hspace{0.5em}\mathrm{MeV}.$ There are also some strong interaction processes for forming di-$\Omega$ such as $\Omega +\overrightarrow{\Omega }(\Omega \Omega {)}_{0^{+}}+\eta ({\eta }^{\prime },\phi )$ and $\Omega +\overrightarrow{\Xi }\left(\Omega \Omega {)}_{0^{+}}{+K(K}^{\star }\right).\mathrm{}$ But these processes only make contributions in the high momentum region, because their threshold energies are around (or greater than) 1 GeV. The cross sections for the pseudoscalar meson production processes are about $2.0–4.5\hspace{0.5em}\mu \mathrm{b},$ and for the vector meson production processes the cross sections are one order larger than those of the pseudoscalar meson production cases. Besides the above processes, a two-step process is also discussed, in which the first step is $\Omega +\overrightarrow{N}(N\Omega {)}_{J^{\pi }{=2\mathrm{}}^{+}}+\pi$ (or $\gamma )$ and the second step is $\Omega +(N\Omega {)}_{2^{+}}\to (\Omega \Omega {)}_{0^{+}}+N.\mathrm{}$ The result shows that the cross sections are quite large for both steps. It seems that some two-step processes might also be important.

Charged current scattering of ${\nu }_{\mu }$ on ${}^{12}\mathrm{C}$ has been studied using a ${\pi }^{+}$ decay-in-flight ${\nu }_{\mu }$ beam at the Los Alamos Neutron Science Center. A sample of $66.9\pm 9.1$ events satisfying criteria for the exclusive reaction ${}^{12}\mathrm{C}({\nu }_{\mu },{\mu }^{-}{)}^{12}{\mathrm{N}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ was obtained using a large liquid scintillator neutrino detector. The observed flux-averaged cross section $(5.6\mathrm{}\pm 0.8\pm 1.0)\times {10}^{-41}\hspace{0.5em}{\mathrm{cm}}^2$ agrees well with reliable theoretical expectations. A measurement was also obtained for the inclusive cross section to all accessible ${}^{12}\mathrm{N}$ states ${}^{12}\mathrm{C}({\nu }_{\mu },{\mu }^{-})X.\mathrm{}$ This flux-averaged cross section is $(10.6\mathrm{}\pm 0.3\pm 1.8)\times {10}^{-40}\hspace{0.5em}{\mathrm{cm}}^2$ which is lower than present theoretical calculations.

The thermal conductivity of the color-flavor locked phase of dense quark matter is calculated. The dominant contribution to the conductivity comes from photons and Nambu-Goldstone bosons associated with the breaking of the baryon number which are trapped in the quark core. Because of their very large mean free path the conductivity is also very large. The cooling of the quark core arises mostly from the heat flux across the surface of direct contact with the nuclear matter. As the thermal conductivity of the neighboring layer is also high, the whole interior of the star should be nearly isothermal. Our results imply that the cooling time of compact stars with color-flavor locked quark cores is similar to that of ordinary neutron stars.

New level schemes of ${}^{141}\mathrm{Ba}$ and ${}^{139}\mathrm{Xe}$ are proposed from analysis of the gamma data from ${}^{252}\mathrm{Cf}$ spontaneous fission in Gammasphere. By analogy with the $N=85\mathrm{}$ even-odd isotones ${}^{149}\mathrm{Gd},$ ${}^{147}\mathrm{Sm},$ and ${}^{145}\mathrm{Nd},$ spins and parities were assigned to the observed excited states in ${}^{141}\mathrm{Ba}$ and ${}^{139}\mathrm{Xe}.$ Level systematics in the $N=85\mathrm{}$ even-odd isotones from Gd $\mathrm{}(Z=64\mathrm{})\mathrm{}$ to Te $\mathrm{}(Z=52\mathrm{})\mathrm{}$ are discussed. The level systematics and comparison with neighboring even-even isotopes indicate that quadrupole and octupole collectivities play a role in ${}^{141}\mathrm{Ba}$ and ${}^{139}\mathrm{Xe}.$ From Gd $\mathrm{}(Z=64\mathrm{})\mathrm{}$ to Te $\mathrm{}(Z=52\mathrm{}),$ increasing excitation energies of the ${13/2}^{+}$ states and lowering relative intensities of the positive-parity bands in the $N=85\mathrm{}$ even-odd isotones may indicate that the octupole strength is becoming weaker for the isotones when approaching the $Z=50\mathrm{}$ closed shell.

Out-of-plane measurements of the angular correlations for the ${}^{12}\mathrm{C}{(e,e}^{\prime }{n)}^{11}\mathrm{C}$ reaction have been performed in the continuum above the giant resonance. The cross sections were directly separated into the longitudinal and transverse, longitudinal-transverse, and transverse-transverse components. Recent random-phase approximation (RPA) predictions reproduce fairly well the angular correlations of both the ${}^{12}\mathrm{C}{(e,e}^{\prime }{n}_{0,1})$ and ${}^{12}\mathrm{C}{(e,e}^{\prime }{p}_0)$ reactions, but the Hartree-Fock predictions fail to reproduce that of ${(e,e}^{\prime }{n}_{0,1}).\mathrm{}$ It suggests that RPA correlations are crucial for the interpretation of the ${(e,e}^{\prime }{n}_{0,1})$ reaction in the observed excitation energy region.

Radiation of dileptons and photons from high-energy nuclear collisions provides information on the space-time evolution of the hot dense matter produced therein. We compute this radiation using relativistic hydrodynamics and a coarse-grained version of the microscopic event generator UrQMD, both of which provide a good description of the hadron spectra. The currently most accurate dilepton and photon emission rates from perturbative QCD and from experimentally based hadronic calculations are used. Comparisons are made to data on central Pb-Pb and Pb-Au collisions taken at the CERN SPS at a beam energy of $158A\hspace{0.5em}\mathrm{GeV}.$ Both hydrodynamics and UrQMD provide very good descriptions of the photon transverse momentum spectrum measured between 1 and 4 GeV, but slightly underestimate the low-mass spectrum of $e^{+}{e}^{-}$ pairs, even with greatly broadened ρ and ω vector mesons. Predictions are given for the transverse momentum distribution of dileptons.