It is shown that the method of lowest order constrained variational (LOCV) which is based on the cluster expansion theory is a reliable many-body technique to calculate the nuclear matter equation of state. In this respect, the state dependent correlation functions and the effective interactions which have been produced by the LOCV calculation with the Reid and Δ-Reid soft core interactions are used to estimate the size of higher order cluster terms such as the effect of three-body cluster energy on the nuclear matter ground state energy. Finally it is shown that the LOCV normalization constraint plays a major role in the convergence of the cluster expansion and the result of LOCV calculation can be as good as more sophisticated approaches which go beyond lowest order.

We discuss forward-backward rapidity correlations in the general situation of asymmetrical collisions, asymmetric rapidity windows, higher rapidities, and higher energy. We give predictions for RHIC and LHC.

A chiral quark-model approach is extended to the study of the $\pi N$ scattering at low energies. The process of ${\pi }^{-}p\to \eta n$ near threshold is investigated. The model is successful in describing the differential cross sections and total cross section near the η production threshold. The roles of the resonances in $n⩽2$ shells are clarified. Near threshold, the $S_{11}(1535)$ dominates the reactions, whereas the interferences from the $S_{11}(1650)$ turn out to be destructive around $W\lesssim 1.6$ GeV. The $D_{13}(1520)$ is crucial to give correct shapes of the differential cross sections. The nucleon pole term contributions are significant. The $P_{11}(1710)$ plays an important role around the center-of-mass energy $W=1.7$ GeV, it is crucial to produce an enhancement in the region of $W>1.6$ GeV as suggested by the data for total cross section. The $t$-channel is negligible in the reactions.

Euclidean point-to-point propagators or wall-to-wall correlators related to exchange by an unstable particle ($\sigma ,\rho ,\omega$ mesons) are modified by the presence of particle width. In particular, the usual method of deriving particle masses from logarithmic derivatives needs to be modified. Similarly, Yukawa-like potentials of nuclear physics due to the exchange of those mesons are significantly modified since the coupling to the decay products is strong. For example, the large-distance asymptotic changes, $~\exp (-M_{\min }r)$, where $M_{\min }$ is the sum of the decay product masses ($2m_{\pi },2m_e,2m_{\nu }$). In the area $M_{\min }r<1,$ the potential has a long-range tail of ∼1/$r^3$. Similar effects appear due to the virtual decays in the electroweak sector of the standard model. The $Z\text{−}\gamma$ mixing via electron loop gives the parity violation potential with the range $1/2m_e$, i.e., the range of the weak interaction increases ${10}^5$ times.

A remarkably simple dependence of fragmentation cross section on average binding energy has been established in experimental data. This dependence was empirically parametrized leading to a very useful formula for extrapolation. We find that the canonical thermodynamic model, which has been used in the past for successful computations of many observables resulting from multifragmentation, reproduces the salient features of fragmentation cross sections of very neutron-rich nuclei very well. This contributes to a theoretical understanding of the observed data.

Relativistic mean-field models of nuclear structure have been enormously successful at reproducing ground-state properties of finite nuclei throughout the periodic table using a handful of accurately calibrated parameters. In this contribution, we use powerful theoretical, experimental, and observational constraints on the equation of state of asymmetric nuclear matter—not employed in the calibration procedure—to validate two such models: NL3 and FSUGold. It is observed that FSUGold is consistent with all these constraints, except perhaps for a high-density equation of state that appears mildly softer than required by astronomical observations. It is argued that incorporating such constraints goes a long way in removing much of the ambiguity left over from the standard calibrating procedure.

Using SU(3) chiral perturbation theory we calculate the density-dependent complex-valued spin-orbit coupling strength $U_{\Sigma \mathit{ls}}(k_f)+i{W}_{\Sigma \mathit{ls}}(k_f)$ of a Σ hyperon in the nuclear medium. The leading long-range $\Sigma N$ interaction arises from iterated one-pion exchange with a Λ or a Σ hyperon in the intermediate state. We find from this unique long-range dynamics a sizable “wrong-sign” spin-orbit coupling strength of $U_{\Sigma \mathit{ls}}(k_{f0})\simeq -20$ MeV fm${}^2$ at normal nuclear matter density ${\rho }_0=0.16$ fm${}^{-3}$. The strong $\Sigma N\to \Lambda N$ conversion process contributes at the same time an imaginary part of $W_{\Sigma \mathit{ls}}(k_{f0})\simeq -12$ MeV fm${}^2$. When combined with estimates of the short-range contribution the total Σ-nuclear spin-orbit coupling becomes rather weak.

Light charged particles emitted at about ${90}^{°}$ in the frame of the projectile-like fragment in semiperipheral collisions of ${}^{93}\mathrm{Nb}+{}^{93}\mathrm{Nb}$ at $38A$ MeV give evidence for the occurrence, in the same class of events, of two different production mechanisms. This is demonstrated by differences in the kinetic energy spectra and in the isotopic composition of the particles. The emission with a softer kinetic energy spectrum and a low $N/Z$ ratio for the hydrogen isotopes is attributed to an evaporation process. The harder emission, with a much higher $N/Z$ ratio, can be attributed to a midvelocity process consisting of a nonisotropic emission, on a short time-scale, from the projectile-like fragment.

Low energy proton-proton scattering is studied in pionless effective field theory. Employing the dimensional regularization and $\overline{\mathrm{MS}}$ and power divergence subtraction schemes for loop calculation, we calculate the scattering amplitude in the ${}^1{S}_0$ channel up to the next-to-next-to leading order and fix low-energy constants that appear in the amplitude by effective range parameters. We study the regularization scheme and scale dependence in the separation of the Coulomb interaction from the scattering length and effective range for the $S$-wave proton-proton scattering.

The results of experiment E906, undertaken at the Alternating Gradient Synchrotron of the Brookhaven National Laboratory (BNL-AGS), were reanalyzed to clarify the signature of the decays of the double- and single-Λ hypernuclei that could have been produced in this experiment. This reanalysis indicates that instead of the reported decay of ${}_{\Lambda \Lambda }^4\mathrm{H}$ through a proposed resonance in ${}_{\Lambda }^4\mathrm{He}$, it is more probable that the decay of the ${}_{\Lambda \Lambda }^7\mathrm{He}$ hypernucleus was observed. This decay was accompanied by a background of coincident decays of pairs of the single hypernuclear fragments ${}_{\Lambda }^3\mathrm{H}$ with ${}_{\Lambda }^4\mathrm{H}$, ${}_{\Lambda }^3\mathrm{H}$ with ${}_{\Lambda }^3\mathrm{H}$, and ${}_{\Lambda }^4\mathrm{H}$ with ${}_{\Lambda }^4\mathrm{H}$. An attempt was also made to determine if any other double or coincident single hypernuclear species could be observed in the data.

A triaxial rotor Hamiltonian is treated by a time-dependent variational principle, using a coherent state as a trial function. The critical points of the constant energy surface depend on the ordering relations satisfied by the three moments of inertia. All three orderings are considered and to each of them a specific wobbling frequency is derived. The transition between two distinct phases is discussed in terms of a cranking Hamiltonian. Four distinct pairs of complex canonical phase-space coordinates are pointed out. Each of them yields, after quantization, a distinct boson expansion for the angular-momentum components. The separation of the potential energy is treated for one of the four phase-space bases. One of the semiclassical descriptions is used for the yrast state energies of ${}^{158}\mathrm{Er}$ and an excellent agreement with experimental data is obtained up to very high angular momentum.

The induced nuclear fission is considered a transport process over the fission barrier underlying dissipative forces. Using a quantum master equation for the reduced density matrix, the influence of microscopical diffusion coefficients on the total fission time and transient time is studied. The influence of transient effects on the probability of the first-chance fission is estimated. For different temperatures and friction coefficients, the quasistationary fission rate is compared with the analytical Kramers formula.

In this work we study the spectral functions of scalar mesons in one- and two-channel cases by using nonlocal interaction Lagrangian(s). When the propagators satisfy the Källen-Lehman representation, a normalized spectral function is obtained, allowing one to take into account finite-width effects in the evaluation of decay rates. In the one-channel case, suitable to the light $\sigma$ and $k$ mesons, the spectral function can deviate consistently from a Breit-Wigner shape. In the two-channel case with one subthreshold channel, the evaluated spectral function is well approximated by a Flatté distribution; when applying the study to the $a_0(980)$ and $f_0(980)$ mesons, the tree-level forbidden KK decay is analyzed.

The explicit inclusion of isospin degrees of freedom in $\mathit{sd}$-shell shell-model calculations with random two-body interactions produces a richer and more varied pattern of ground-state spins and isospins than has been found with only a single type of valence nucleon. The degree of dominance of $0^{+}$ ground states in even-even nuclei is far from uniform in the presence of different numbers of valence neutrons and protons and is mirrored by the prevalence of $1^{+}$ ground states in odd-odd nuclei. Random interactions distinguish between the ground-state patterns of even-even and odd-odd nuclei. The natural isospin ordering observed in nuclei (with states of minimum isospin lying lowest in energy and increasing in energy with increasing isospin) is also prominent despite the randomness of the interactions. Universal $0^{+}$ even-even ground states and almost universal natural isospin ordering, as observed in nuclei, evidently still require two-body interactions with specific dynamic properties.

By applying particle-number projection to the static-path approximation (SPA), the heat capacity and the breakdown of pairing correlations are investigated in the thermally excited, superfluid systems ${}^{172}\mathrm{Yb}$, ${}^{94}\mathrm{Mo}$, and ${}^{56}\mathrm{Fe}$. For the heavy nucleus ${}^{172}\mathrm{Yb}$, the heat capacities in both the SPA and the number-projected SPA (NPSPA) exhibit an $\mathcal{S}$ shape; the difference between the SPA and NPSPA heat-capacity curves is not very large and the particle-number projection thereby enhances the $\mathcal{S}$ shape already seen in the SPA. The temperature at which the $\mathcal{S}$-shape of heat capacity curve occurs parallels the temperature of the breakdown of pairing correlations as indicated by the effective pairing gap. However, for the comparatively lighter nuclei ${}^{94}\mathrm{Mo}$ and ${}^{56}\mathrm{Fe}$, the SPA does not produce an $\mathcal{S}$-shaped heat capacity on its own; only after particle-number projection the $\mathcal{S}$ shape appears in the heat-capacity curve. For ${}^{94}\mathrm{Mo}$, we compare the NPSPA result with thermal odd-even mass differences, which are regarded as a direct measure of the pairing gap.

Excited low-spin, nonyrast states of ${}^{168}\mathrm{Hf}$ were populated in ${\beta }^{+}/\epsilon$ decay and studied through γ-ray spectroscopy to assess the nature of low-lying $K^{\pi }=0^{+},2^{+}$ intrinsic excitations. Coincidence data provided improved measurements of the decay properties of the low-lying states, and $\gamma \text{−}\gamma$ angular correlation measurements yielded spin assignments for several levels as well as $E2/M1$ mixing ratios. The resulting level scheme of ${}^{168}\mathrm{Hf}$ is compared with the predictions of new simple geometrical models, including the confined beta soft model and the Davidson potential. It is found that the predictions for most observables are similar for all the models and in agreement with the data on ${}^{168}\mathrm{Hf}$. However, large differences exist in the predictions for the excited $K=0^{+}$ sequence, with the Davidson potential best reproducing the data in ${}^{168}\mathrm{Hf}$.

β decay of ${}^{113}\mathrm{Cd}$ was studied with the help of a low background CdWO${}_4$ crystal scintillator (mass of 434 g) in an experiment at the Gran Sasso National Laboratories of the INFN for a period of 2758 h. The shape of the spectrum of the non-unique fourth-forbidden decay of ${}^{113}\mathrm{Cd}$ was measured, and the half-life of ${}^{113}\mathrm{Cd}$ was determined as $T_{1/2}=(8.04\pm 0.05)\times {10}^{15}$ yr.

Based on the semi-inclusive deep inelastic scattering data obtained by the HERMES experiment on deuterium, nitrogen and krypton nuclei, it is shown that a ratio of multiplicities on nucleus and deuterium (per nucleon) for given hadron $R_M^h$ can be parametrized in a form of a linear polynomial $a_{11}+\tau a_{12}$, where τ is the formation time, which depends on the energy of the virtual photon ν and fraction of that energy $z$ carried by the final hadron. Three widely known parametrizations for τ were used for the performed fit. The fit parameters $a_{11}$ and $a_{12}$ do not depend on ν and $z$.

The possibility of studying particle-like states near the Fermi surfaces of exotic nuclei by using measurements of heavy-ion-induced single-nucleon pickup reactions with in-flight separated rare-isotope beams is discussed. The analysis of an exploratory data set for the intermediate-energy ${}^9\mathrm{Be}$(${}^{20}\mathrm{Ne}$,${}^{21}\mathrm{Na}$)$X$ proton pickup reaction measured using a ${}^{20}\mathrm{Ne}$ beam at 63 MeV per nucleon is reported. The data are compared with expectations based on model calculations of the transfer reaction cross sections and the ${}^{21}\mathrm{Na}$ residue spectroscopy prediction by the $\mathit{sd}$-shell model. The measured cross sections are broadly consistent with these expectations.