In nuclear matter, the pion weak decay constant is separated into two components $f_t$ and $f_s$ corresponding to the time and space components of the axial-vector current. Using QCD sum rules, we compute the two decay constants from the pseudoscalar-axial vector correlation function in the matter $i\int d^{4}x\hspace{0.5em}{e}^{\mathrm{ip}\cdot x}〈\rho |T\left[\overline{d}\mathrm{}\right(x\left)i{\gamma }_{5}u\right(x\left)\mathrm{}\hspace{0.5em}ū\mathrm{}\right(0\left)\mathrm{}{\gamma }_{\mu }{\gamma }_{5}d\right(0\left)\mathrm{}\right]|\rho 〉.$ It is found that the sum rule for $f_t$ satisfies the in-medium Gell-Mann–Oakes–Renner relation precisely, while the $f_s$ sum rule does not. The $f_s$ sum rule contains the non-negligible contribution from the dimension 5 condensate $〈\overline{q}{\mathrm{iD}}_0{\mathrm{iD}}_{0}q{〉}_N+\frac{1}{8}〈\overline{q}{g}_s\sigma \cdot \mathcal{G}q{〉}_N$ in addition to the in-medium quark condensate. Using a standard set of QCD parameters and ignoring the in-medium change of the pion mass, we obtain $f_t=105\mathrm{}\hspace{0.5em}\mathrm{MeV}$ at the nuclear saturation density. The prediction for $f_s$ depends on the dimension 5 condensate and on the Borel mass. However, because of the positivity condition for the dimension 5 condensate, the operator product expansion constrains that $f_s{/f}_t>~1,$ which does not agree with the “tree level” prediction from the in-medium chiral perturbation theory. Depending on the value of the dimension 5 condensate, $f_s$ at the saturation density is found to be in the range $112–134\hspace{0.5em}\mathrm{MeV}$ at the Borel mass $M^2\sim 1\hspace{0.5em}{\mathrm{GeV}}^2.$

Analyzing the energy spectrum, $E2\mathrm{}$ transition rates, and branching ratios, it is shown that the nucleus ${}^{108}\mathrm{Pd}$ provides an empirical example with the transitional dynamical symmetry E(5), and the finite boson number effect is not obvious.

Fission fragment anisotropies have been measured for ${}^{10}\mathrm{B}\left(\mathrm{spin}{=3\mathrm{}}^{+}\right),$ ${}^{11}\mathrm{B}\left(\mathrm{spin}{=3/2\mathrm{}}^{-}{)+}^{237}\mathrm{Np}\right(\mathrm{spin}{=5/2\mathrm{}}^{+})$ reactions at projectile energies below and above the Coulomb barrier of the respective systems. The experimental fragment anisotropies are consistent with the results of calculations based on the entrance-channel-dependent (ECD) K-state model with the inclusion of ground-state spins of the projectile and target. Further, the fragment anisotropies also show very little deviation from the statistical saddle point model (SSPM) predictions for both the systems, unlike for spin-0 projectile and target systems reported earlier. These results are in very good agreement with the fact that the subbarrier anomaly in fragment anisotropies seen for the actinide target systems gets washed out for systems having large target and/or projectile ground-state spins.

The Oak Ridge Electron Linear Accelerator (ORELA) was used to measure neutron total and capture cross sections of natural chlorine in the energy range from 100 eV to 600 keV. We performed an R-matrix analysis of our new capture and transmission data up to 500 keV. From these resonance parameters new $(n,\gamma )$ astrophysical reaction rates were determined over the entire energy range needed by the latest stellar models of the s process.

This paper presents a formulation of a local density approximation for fermion systems with pairing correlations based on a rapidly converging renormalization scheme for the pairing field.

We have performed shell-model calculations for ${}^{134,135}\mathrm{Sn}$ using a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. Comparison shows that the calculated results for ${}^{134}\mathrm{Sn}$ are in very good agreement with recent experimental data. This supports confidence in our predictions of the hitherto unknown spectrum of ${}^{135}\mathrm{Sn}.$

Excited states in the proton emitter ${}^{105}\mathrm{Sb}$ have been investigated for the first time. The nucleus was populated in the reaction ${}^{50}\mathrm{Cr}{(}^{58}\mathrm{Ni},1p2n).\mathrm{}$ The GAMMASPHERE Ge-detector array was used together with Microball and the Neutron Shell for selection of the reaction channel. The experimental level scheme agrees well with results of a shell model calculation that uses realistic effective interactions derived from the CD-Bonn nucleon-nucleon interaction and ${}^{100}\mathrm{Sn}$ as a closed-shell core.

Spontaneous emission of some C, O, F, Ne, Mg, and Si isotopes, from heavy parent nuclei, have been experimentally observed since 1984, confirming earlier predictions. Experimental difficulties are mainly related to the low yield in the presence of a strong background of $\alpha$ particles. Until now, only some of the most favorable cases were investigated, leading to magic or almost magic proton and neutron numbers of daughter nuclei. We present a systematics of experimental results compared to calculations, clearly showing other possible candidates for future experiments. Universal curves may be used to estimate the expected half-lives.

A theory of three-body reactions is presented, applicable to atomic and nuclear interactions, in which the colliding systems may be charged and composite, subject to the condition that the total energy lies below the threshold for breakup of any of the three bound systems. A variational principle for elements of the scattering matrix is derived, and a decomposition of each trial function into open- and closed-channel parts is presented that allows for the use of a subsidiary minimum principle for the systematic improvement of the closed-channel component. A detailed analysis of the structure of the trial functions is provided through a representation of the exact wave function in terms of the solution of integral equations of the Faddeev type, generalized to allow for long-range Coulomb interactions between pairs (through the appearance of Coulomb-distorted Green’s functions in the kernel of the integral equation) as well as for the internal structure of the clusters. The integral equations provide a general foundation for the theory. In particular, they lead to a formal justification of the variational identity presented here and serve to determine how the closed-channel component of the trial function is to be defined to establish the subsidiary minimum principle.

The near-barrier and sub-barrier fusion of light unstable nuclei and their respective stable isotopes with heavy targets ${(}^{4,6}\mathrm{He}{+}^{209}\mathrm{Bi},$ ${}^{4,6}\mathrm{He}{+}^{238}\mathrm{U},$ ${}^{9,11}\mathrm{Be}{+}^{209}\mathrm{Bi},$ and ${}^9\mathrm{Be}{+}^{208}\mathrm{Pb})$ is investigated via coupled channel calculations. The entrance channel optical potential is generated via a microscopic BDM3Y1 interaction. A rather satisfactory description of the experimental data is obtained under the condition that the real part of the optical potential has to be reduced for the weakly bound and halo systems. This reduction proves to be the fundamental difference in treating stable and weakly bound nuclei, and can be attributed to the loss of a flux due to breakup effects.

The differential transverse flow of protons and pions in central C-Ne and C-Cu collisions at a beam energy of 3.7 GeV/nucleon was measured as a function of transverse momentum at the SKM-200-GIBS setup of JINR. In agreement with predictions of a transversely moving thermal model, the strength of proton differential transverse flow is found to first increase gradually and then saturate with the increasing transverse momentum in both systems. While pions are preferentially emitted in the same direction of the proton transverse flow in the reaction of C-Ne, they exhibit an antiflow to the opposite direction of the proton transverse flow in the reaction of C-Cu due to stronger shadowing effects of the heavier target in the whole range of transverse momentum.

The structures of the even-even superheavy nuclei with proton number $Z=100\mathrm{}–114$ are systematically investigated using self-consistent relativistic mean-field theory. The calculated binding energies are in good agreement with all available experimental data. The experimental alpha decay energies and lifetimes of the newly discovered superheavy nuclei are also reasonably reproduced by the model. Large scale calculations with a quadrupole moment constraint clearly show the variation of energy with the quadrupole deformation parameter. It reliably demonstrates that there is shape coexistence in superheavy nuclei. In some cases the configuration with superdeformation may be the ground state of superheavy nuclei near $Z=114\mathrm{}$ and $N=174.\mathrm{}$

A good quality scaling of the cluster size distributions is obtained for the lattice gas model using the Fisher’s ansatz for the scaling function. This scaling identifies a pseudocritical line in the phase diagram of the model that spans the whole (subcritical to supercritical) density range. The independent cluster hypothesis of the Fisher approach is shown to describe correctly the thermodynamics of the lattice only far away from the critical point.

The structure of the transitional nucleus ${}^{85}\mathrm{Zr}$ has been investigated through spectroscopy and lifetime measurements. States up to spins of $\frac{45}{2}ħ$ and $\frac{39}{2}ħ$ in the positive and negative parity bands, respectively, have been established through $\gamma -\gamma$ coincidence measurements. The results indicate that there is a competition between collective and noncollective modes of excitation. Two pronounced band crossings have been observed in the positive parity sequence, while none is evident in the negative parity states. The pattern of shape evolution in the positive and negative parity bands is markedly different. The results of the experiments qualitatively corroborate the predictions of total Routhian surface calculations.

The loss of flux from the elastic channel due to breakup is calculated in a model case (56 MeV deuterons on ${}^{51}\mathrm{V})$ where the breakup contribution to the imaginary part of the nucleus-nucleus optical potential has been explicitly determined. We find that most of the flux is lost in a cap-shaped region near the nuclear surface while a smaller part is lost at a refractive focus.

We recently proposed an approach to high-energy nuclear scattering, which treats the initial stage of heavy-ion collisions in a sophisticated way. We are able to calculate macroscopic quantities like energy density and velocity flow at the end of this initial stage, after the two nuclei having penetrated each other. In other words, we provide the initial conditions for a macroscopic treatment of the second stage of the collision. We address in particular the question of how to incorporate the soft component properly. We find almost perfect “Bjorken scaling”: the rapidity coincides with the space-time rapidity, whereas the transverse flow is practically zero. The distribution of the energy density in the transverse plane shows typically a very “bumpy” structure.

The empirical value of the real part of the pion-deuteron scattering length can be well understood in terms of the dominant isovector $\pi N$ double scattering contribution. We calculate in chiral perturbation theory all one-pion loop corrections to this double scattering term which in the case of $\pi N$ scattering close the gap between the current-algebra prediction and the empirical value of the isovector threshold T-matrix $T_{\pi N}^{-}.$ In addition to closing this gap, there is in the $\pi d$ system a loop-induced off-shell correction for the exchanged virtual pion. Its coordinate space representation reveals that it is equivalent to $2\pi$ exchange in the deuteron. We evaluate the chirally corrected double scattering term and the off-shell contribution with various realistic deuteron wave functions. We find that the off-shell correction contributes at most $-8\%$ and that the isovector double scattering term explains at least 90% of the empirical value of the real part of the $\pi d$-scattering length.

We discuss characteristic experimental signatures related to the formation of domains of disoriented chiral condensate triggered by the axial anomaly in relativistic heavy-ion collisions. We predict that the enhancement of the fraction of neutral pions compared to all pions depends on the angle of emission with respect to the scattering plane and is concentrated at small transverse momentum and small rapidity in the center-of-mass frame. The anisotropy with respect to the reaction plane is also observable in the inclusive photon distribution.

Symmetric nuclear matter is studied in the self-consistent, in-medium T-matrix approach. One-body spectral function, optical potential, and scattering width are calculated. Properties of quasiparticle excitations at the Fermi surface are discussed. Dispersive self-energies are dominated by contributions from the ${}^1{S}_0,$ ${}^3{S}_1{-}^3{D}_1,$ and ${}^3{P}_1$ partial waves.