Possible deformation of odd-$N$ nuclei with $N\approx 28$ toward the neutron drip line is investigated using the Nilsson diagram based on deformed Woods-Saxon potentials. Both weakly-bound and resonant one-particle levels are properly obtained by directly solving the Schrödinger equation in mesh of space coordinate with the correct boundary condition. If we use the same diffuseness of the potential as that of $\beta$-stable nuclei, the energy difference between the neutron $2p_{3/2}$ and $1f_{7/2}$ levels becomes very small or the $N=28$ energy gap almost disappears, as the binding energies of those levels approach zero. This suggests that the ground states of those neutron drip line nuclei are likely to be deformed. In particular, the spin-parity and the magnetic moment of the ground state of odd-$N$ nuclei, ${}_{16}^{43}{\mathrm{S}}_{27}$ and ${}_{16}^{45}{\mathrm{S}}_{29}$, are examined. Moreover, it is suggested that in ${}_{12}^{39}{\mathrm{Mg}}_{27}$ lying outside the drip line the lowest resonant state may have $5/2^{-}$, if the $N=28$ energy gap almost vanishes.

We report the first measurements of the total cross section of the reaction $K^{-}p\to {\Sigma }^0\gamma$ at eight beam momenta from 514 to 750 MeV/$c$. The data were obtained at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory using the Crystal Ball detector consisting of 672 NaI crystals. All charged particles were vetoed by a barrel of plastic scintillators, resulting in a study of only the neutral decays of the ${\Sigma }^0$. The prompt photon and the photons from the decay products of ${\Sigma }^0$ were detected for each reconstructed event; the neutron was also detected in a small fraction of the events.

A half-life of 2.2 ± 0.2 s has been deduced for the ground-state $\beta$ decay of ${}^{84}\mathrm{Mo}$, more than $1\sigma$ shorter than the previously adopted value. ${}^{84}\mathrm{Mo}$ is an even-even $N=Z$ nucleus lying on the proton dripline, created during explosive hydrogen burning in type I x-ray bursts in the rapid proton capture ($\mathit{rp}$) process. The effect of the measured half-life on $\mathit{rp}$-process reaction flow is explored. Implications on theoretical treatments of nuclear deformation in ${}^{84}\mathrm{Mo}$ are also discussed.

We have extended the density matrix renormalization group (DMRG) approach to two-fluid open many-fermion systems governed by complex-symmetric Hamiltonians. The applications are carried out for three- and four-nucleon (proton-neutron) systems within the Gamow shell model (GSM) in the complex-energy plane. We study necessary and sufficient conditions for the GSM+DMRG method to yield the correct ground-state eigenvalue and discuss different truncation schemes within the DMRG. The proposed approach will enable configuration interaction studies of weakly bound and unbound strongly interacting complex systems, which, because of a prohibitively large size of Fock space, cannot be treated by means of the direct diagonalization.

We discuss the origin of the narrowness of the single peak at mass-symmetric division in the fragment mass-yield curve for spontaneous fission of ${}^{258}\mathrm{Fm}$. For this purpose, we employ the macroscopic-microscopic model and calculate a potential-energy curve at the mass-symmetric compact scission configuration, as a function of the fragment mass number, which is obtained from the single-particle wave-function densities. In the calculations, we minimize total energies by varying the deformations of the two fragments, with constraints on the mass quadrupole moment, and by keeping the neck radius zero. The energies thus become functions of mass asymmetry. Using the obtained potential, we solve the one-dimensional Schrödinger equation with a microscopic coordinate-dependent inertial mass to calculate the fragment mass-yield curve. The calculated mass yield, expressed in terms of the microscopic mass density, is consistent with the extremely narrow experimental mass distribution.

Azimuthally sensitive femtoscopy for heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) is explored within the approach consisting of the hydrodynamics of perfect fluid followed by statistical hadronization. It is found that for the RHIC initial conditions, employing the Gaussian shape of the initial energy density, the very same framework that reproduces the standard soft observables [including the transverse-momentum spectra, the elliptic flow, and the azimuthally averaged Hanbury-Brown-Twiss (HBT) radii] leads to a proper description of the azimuthally sensitive femtoscopic observables; we find that the azimuthal variation of the side and out HBT radii as well as out-side cross term are very well reproduced for all centralities. Concerning the dependence of the femtoscopic parameters on $k_T$ we find that it is very well reproduced. The model is then extrapolated to the LHC energy. We predict the overall moderate growth of the HBT radii and the decrease of their azimuthal oscillations. Such effects are naturally caused by longer evolution times. In addition, we discuss in detail the space-time patterns of particle emission. We show that they are quite complex and argue that the overall shape seen by the femtoscopic methods cannot be easily disentangled on the basis of simple-minded arguments.

Deeply bound $\overline{K}\mathit{NN}$, $\overline{K}\mathit{NNN}$, and $\overline{K}\mathit{NNNN}$ states are discussed. The effective force exerted by the $\overline{K}$ meson on the nucleons is calculated with static nucleons. Next the binding energies are obtained by solving the Schrödinger equation or by variational calculations. The dominant attraction comes from the $S$-wave $\Lambda (1405)$ and an additional contribution is due to $\Sigma (1385)$. The latter state is formed at the nuclear peripheries and absorbs a sizable piece of the binding energy. It also generates new branches of quasibound states. The lowest binding energies based on a phenomenological $\overline{K}\mathit{N}$ input fall into the 40- to 80-MeV range for $\overline{K}\mathit{NN}$, 90–150 MeV for $\overline{K}\mathit{NNN}$, and 120–220 MeV for $\overline{K}\alpha$ systems. The uncertainties are due to unknown $\overline{K}\mathit{N}$ interactions in the distant subthreshold energy region.

In this work, we have evaluated the unscreened electron inelastic scattering cross sections in the 1–100 keV range with a second order perturbation theory. The WKB approximation and DWBA calculations for low-energy electrons encountered show less than a 3% difference. Applications have been performed for two nuclei, namely ${}^{110}\mathrm{Ag}$ and ${}^{201}\mathrm{Hg}$.

The nucleon final-state interaction in inclusive electron-nucleus quasielastic scattering is studied. Based on the unitarity equation satisfied by the scattering-wave operators, a doorway model is developed to take into account the final-state interaction including the Pauli blocking of nucleon knockout. The model uses only experimental form factors as the input and can be readily applied to light- and medium-mass nuclei. Pauli blocking effects in these latter nuclei are illustrated with the case of the Coulomb interaction. Significant effects are noted for beam energies below $~350$ MeV/$c$ and for low momentum transfers.

Momentum-space three-body Faddeev-like equations are used to calculate elastic, transfer, and charge-exchange reactions resulting from the scattering of deuterons on ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ or protons on ${}^{13}\mathrm{C}$ and ${}^{17}\mathrm{O}$, with ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ treated as inert cores. All possible reactions are calculated in the framework of the same model space. Comparison with previous calculations based on approximate methods used in nuclear reaction theory is made.

We analyze recent data on particle production yields obtained in $p\text{−}p$ collisions at SPS and RHIC energies within the statistical model. We apply the model formulated in the canonical ensemble and focus on strange particle production. We introduce different methods to account for strangeness suppression effects and discuss their phenomenological verification. We show that at RHIC the midrapidity data on strange and multistrange particle multiplicity can be successfully described by the canonical statistical model with and without an extra suppression effects. On the other hand, SPS data integrated over the full phase-space require an additional strangeness suppression factor that is beyond the conventional canonical model. This factor is quantified by the strangeness saturation parameter or strangeness correlation volume. Extrapolating all relevant thermal parameters from SPS and RHIC to LHC energy we present predictions of the statistical model for particle yields in $p\text{−}p$ collisions at $\sqrt{s}=14$ TeV. We discuss the role and the influence of a strangeness correlation volume on particle production in $p\text{−}p$ collisions at LHC.

We calculate the neutrino emissivity of superfluid neutron matter in the inner crust of neutron stars. We find that neutrino emission due to fluctuations resulting from the formation of Cooper pairs at finite temperature is highly suppressed in nonrelativistic systems. This suppression of the pair-breaking emissivity in a simplified model of neutron matter with interactions that conserve spin is of the order of $v_F^4$ for density fluctuations and $v_F^2$ for spin fluctuations, where $v_F$ is the Fermi velocity of neutrons. The larger suppression of density fluctuations arises because the dipole moment of the density distribution of a single component system does not vary in time. For this reason, we find that the axial current response (spin fluctuations) dominates. In more realistic models of neutron matter that include tensor interactions where the neutron spin is not conserved, neutrino radiation from bremsstrahlung reactions occurs at order $v_F^0$. Consequently, even with the suppression factors due to superfluidity, this rate dominates near $T_C$. Present calculations of the pair-breaking emissivity are incomplete because they neglect the tensor component of the nucleon-nucleon interaction.

The three-body force (TBF) effect is studied in nucleus-nucleus elastic scattering with the use of a new complex $G$-matrix interaction that reproduces well proton-nucleus scattering observables. The TBF contribution is included in the $G$-matrix so as to give a reasonable nuclear-matter saturation curve. The ${}^{16}\mathrm{O}$$+$${}^{16}\mathrm{O}$ potential is obtained by the double-folding procedure with the $G$-matrix interaction. The observed cross sections for ${}^{16}\mathrm{O}$$+$${}^{16}\mathrm{O}$ elastic scattering at $E/A=70$ MeV are nicely reproduced up to the most backward scattering angles when the TBF effect is included.

Photoexcitation of the $N=50$ nucleus ${}^{89}\mathrm{Y}$ has been performed at the bremsstrahlung facility at the superconducting electron accelerator ELBE at electron energies of $E_e^{\mathrm{kin}}=9.5$ and 13.2 MeV. About 250 levels up to the neutron-separation energy were identified. Statistical methods were applied to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. The photoabsorption cross section derived in this way up to the neutron-separation energy is combined with the photoabsorption cross section obtained from ($\gamma$, $n$) data and provides information about the extension of the giant dipole resonance toward energies below the neutron-separation energy. An enhancement of $E1$ strength has been found in the range from about 6 to 11 MeV. The experimental photoabsorption cross sections of ${}^{89}\mathrm{Y}$ and of the neighboring $N=50$ isotones ${}^{88}\mathrm{Sr}$ and ${}^{90}\mathrm{Zr}$ are compared with predictions of the quasiparticle-random-phase approximation.

We employ a simple effective model to study the chiral dynamics of two flavors of quarks at finite temperature and density. In particular, we determine the phase diagram in the plane of temperature and baryon chemical potential as a function of the pion mass. An interesting phase structure occurs that results in zero, one, or two critical points depending on the value of the vacuum pion mass.

The inner crust of neutron stars, formed of a crystal lattice of nuclear clusters immersed in a sea of unbound neutrons, may be the unique example of periodic nuclear systems. We have calculated the neutron-specific heat in the shallow part of the crust using the band theory of solids with Skyrme nucleon-nucleon interactions. We have also tested the validity of various approximations. We have found that the neutron-specific heat is well described by that of a Fermi gas, while the motion of the unbound neutrons is strongly affected by the nuclear lattice. These apparently contradictory results are explained by the particular properties of the neutron Fermi surface.

A density matrix functional theory is constructed semi-empirically for the two-level Lipkin model. This theory, based on natural orbitals and occupation numbers, is shown to provide a good description for the ground state energy of the system as the two-body interaction and particle number vary. The application of density matrix functional theory to the Lipkin model illustrates that it could be a valuable tool for systems presenting a shape phase transition such as nuclei. The improvement of one-body observables description as well as the interest for energy density functional theory are discussed.

The two-neutron transfer reaction ${}^9\mathrm{Be}$(${}^{16}\mathrm{O}$, ${}^{14}\mathrm{O}$)${}^{11}\mathrm{Be}$[${}^{10}\mathrm{Be}$ $+n$] has been used to measure the branching ratios for the neutron decay of excited states of ${}^{11}\mathrm{Be}$. The ${}^{14}\mathrm{O}$ ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the ${}^{10}\mathrm{Be}$ fragments of the decaying ${}^{11}\mathrm{Be}$${}^{*}$ recoil were measured in coincidence with the ${}^{14}\mathrm{O}$ ejectile using a double-sided silicon strip detector array at backward angles. This enabled a kinematic reconstruction of the reaction to be performed. Theoretical decay branch ratios were calculated using barrier penetrability factors and were compared to the measured ratios to provide information on the relative reduced widths of the states. The decay widths have been used to link states in ${}^{11}\mathrm{Be}$ with a common structure and structurally to states in the daughter nucleus ${}^{10}\mathrm{Be}$. The $3/2^{-}\hspace{0.5em}\hspace{0.5em}8.82$-MeV state was identified as a candidate for a molecular band head.

We theoretically examine production of the neutron-rich ${}_{\Lambda }^{10}\mathrm{Li}$ hypernucleus by a double-charge exchange (${\pi }^{-}$, $K^{+}$) reaction on a ${}^{10}\mathrm{B}$ target with distorted-wave impulse approximation calculations. We calculate the inclusive spectrum at the incident momentum 1.20 GeV/$c$ by a one-step mechanism ${\pi }^{-}p\to K^{+}{\Sigma }^{-}$ via ${\Sigma }^{-}$ doorways caused by a ${\Sigma }^{-}p\leftrightarrow \Lambda n$ coupling. The resultant spectrum can explain the magnitude of the recent experimental data, so that the ${\Sigma }^{-}$ admixture probability in ${}_{\Lambda }^{10}\mathrm{Li}$ is found to be of the order of ${10}^{-1}\%$. The (${\pi }^{-}$, $K^{+}$) reaction provides the ability to extract properties of wave functions with $\Lambda \text{−}\Sigma$ coupling effects in neutron-rich nuclei, as well as the reaction mechanism.

During nova outbursts the decay of ${}^{18}\mathrm{F}$ is the main source of $\gamma$-ray emission at and below 511 keV. In spite of much experimental effort, the quantity of ${}^{18}\mathrm{F}$ synthesized still suffers from large uncertainties which arise mainly from the ${}^{18}\mathrm{F}$($p$, $\alpha$)${}^{15}\mathrm{O}$ reaction cross section at low energies. We report here on a new direct measurement carried out at the Louvain-la-Neuve RIB facility of Louvain-la-Neuve using an isobarically pure ${}^{18}\mathrm{F}$ beam impinging on a thin polyethylene target. Cross sections down to a center-of-mass energy of 400 keV have been obtained and the results together with previous experimental data were compared to $\mathcal{R}$-matrix calculations. The effect of the relative contribution of the two low-lying $3/2^{+}$ resonances as well as the sensitivity of the calculations to the $\mathcal{R}$-matrix radius is studied in detail.