The particle number and energy fluctuations in a system of charged particles are studied in the canonical ensemble for nonzero net values of the conserved charge. In the thermodynamic limit, the fluctuations in the canonical ensemble differ from those in the grand canonical ensemble. A system with several species of particles is considered. We calculate the quantum statistical effects that can be taken into account for the canonical ensemble fluctuations in the infinite-volume limit. The fluctuations of the particle numbers in the pion-nucleon gas are considered in the canonical ensemble as an example of the system with two conserved charges—baryonic number and electric charge.

The ground state binding energies of closed shell nuclei such as ${}^4\mathrm{He},{}^{12}\mathrm{C},{}^{16}\mathrm{O},{}^{28}\mathrm{Si},{}^{32}\mathrm{S},{}^{40}\mathrm{Ca}$, and ${}^{56}\mathrm{Ni}$ are calculated by using the local density approximation in the harmonic oscillator basis. Different channel effective two-body interactions are generated from the lowest order constrained variational calculation for nuclear matter with the Reid68 and Δ-Reid68 potentials. It is shown that the unlike nuclear matter, Reid68 potential gives ground state binding energies closer to the experimental data with respect to the Δ-Reid68 interaction. The different channel effective interactions as well as one- and two-body density distribution functions are discussed and compared with the results of other approaches such as the correlated basis function, variational fermion hypernetted chain, variational cluster Monte Carlo, Brueckner-Hartree-Fock, fermionic molecular dynamics, and coupled cluster.

High-spin excited states have been identified in the $N=Z+1$ nucleus ${}^{91}\mathrm{Rh}$ with the reaction ${}^{54}\mathrm{Fe}$(${}^{40}\mathrm{Ca},p2n\gamma$) at 130 MeV, using the GASP array, the ISIS silicon array, and the n-ring detector system. Two structures have been observed, the positive-parity yrast sequence above the ($9/2^{+}$) ground state and a sequence assigned to negative parity that is built on a possible ($1/2^{-}$) isomeric state. The observed structures are compared with various shell-model calculations in the ($p_{1/2},g_{9/2}$) space.

We present a new method of bosonization of fermion systems applicable when the partition function is dominated by composite bosons. By restricting the partition function to such states, we obtain a Euclidean bosonic action from which we derive the Hamiltonian. Such a procedure respects all the fermion symmetries, particularly the fermion number conservation, and provides a boson mapping of all fermion operators.

We use the relativistic distorted-wave impulse approximation (RDWIA) to study the effects of negative-energy components of Dirac wave functions on the left-right asymmetry for $(e,e^{\text{'}}p)$ reactions on ${}^{16}\mathrm{O}$ with $0.2\le Q^2\le 0.8$ and ${}^{12}\mathrm{C}$ with $0.6\le Q^2\le 1.8(\text{GeV}/c){}^2$. Spinor distortion is more important for the bound state than for the ejectile and the net effect decreases with $Q^2$. Spinor distortion breaks Gordon equivalence and the data favor the CC2 operator with intermediate coupling to the sea. The left-right asymmetry for $Q^2\lesssim 1.2(\text{GeV}/c){}^2$ is described well by RDWIA calculations, but at $Q^2=1.8(\text{GeV}/c){}^2$ the observed variation with missing momentum is flatter than predicted.

We have studied volume integrals of the central part of optical potentials extracted from data analyses for a variety of light and heavy systems. The data-extracted integrals present a quite simple behavior as a function of the relative velocity between target and projectile. This behavior is system independent and, therefore, it reflects a feature of the effective nucleon-nucleon interaction itself. The overall results are in good agreement with the predictions of the São Paulo potential, which is a model for the nuclear interaction that so far has been employed mostly in analyses of heavy-ion reactions.

The spectrum of meson and diquark excitations of dense cold quark matter is investigated within the framework of a Nambu–Jona-Lasinio-type model for light quarks of two flavors. It was found that a first-order phase transition occurs when the chemical potential μ exceeds the critical value ${\mu }_c=350\text{MeV}$. Above ${\mu }_c$, the diquark condensate $\langle \mathit{qq}\rangle$ forms, breaking the color symmetry of strong interaction. The masses of π and σ mesons are shown to grow with the chemical potential μ in the color-superconducting phase, but the mesons themselves become almost stable particles. Moreover, we have found in this phase an abnormal number of three, instead of five, Nambu-Goldstone bosons, together with a color doublet of light stable diquark modes and a color-singlet heavy diquark resonance with mass $~$1100 MeV. In the color-symmetric phase, i.e., for $\mu <{\mu }_c$, a mass splitting of diquarks and antidiquarks is shown to arise if $\mu \ne 0$, contrary to the case of a vanishing chemical potential, in which the masses of antidiquarks and diquarks are degenerate at the value $~$700 MeV.

Different models for conserved two- and three-body electromagnetic currents are constructed from two- and three-nucleon interactions, using either meson-exchange mechanisms or minimal substitution in the momentum dependence of these interactions. The connection between these two different schemes is elucidated. A number of low-energy electronuclear observables, including (i) np radiative capture at thermal neutron energies and deuteron photodisintegration at low energies, (ii) nd and pd radiative capture reactions, and (iii) isoscalar and isovector magnetic form factors of ${}^3\mathrm{H}$ and ${}^3\mathrm{He}$, are calculated to make a comparative study of these models for the current operator. The realistic Argonne $v_{18}$ two-nucleon and Urbana IX or Tucson-Melbourne three-nucleon interactions are taken as a case study. For $A=3$ processes, the bound and continuum wave functions, both below and above deuteron breakup threshold, are obtained with the correlated hyperspherical harmonics method. Three-body currents give small but significant contributions to some of the polarization observables in the ${}^2\mathrm{H}$($p,\gamma$)${}^3\mathrm{He}$ process and the ${}^2\mathrm{H}$($n,\gamma$)${}^3\mathrm{H}$ cross section at thermal neutron energies. It is shown that the use of a current that did not exactly satisfy current conservation with the two- and three-nucleon interactions in the Hamiltonian was responsible for some of the discrepancies reported in previous studies between the experimental and theoretical polarization observables in pd radiative capture.

A multichannel algebraic scattering theory has been used to study the properties of nucleon scattering from ${}^{12}\mathrm{C}$ and of the subthreshold compound nuclear states. The theory accounts for properties in the compound nuclei to ∼10 MeV. All compound and quasicompound resonances observed in total cross-section data are matched, and, on seeking solutions of the method at negative energies, all subthreshold states in ${}^{13}\mathrm{C}$ and ${}^{13}\mathrm{N}$ are predicted with the correct spin-parities and with reasonable values for their energies. A collective-model prescription has been used to define the initiating nucleon-${}^{12}\mathrm{C}$ interactions and, via use of orthogonalizing pseudopotentials, account is made of the Pauli principle. Information is extracted on the underlying structure of each state in the compound systems by investigating the zero-deformation limit of the results.

We systematically study $K^{+}$ observables in nucleus-nucleus collisions at 1–2A GeV within the Boltzmann-Uehling-Uhlenbeck (BUU) transport model. We compare our calculations with the KaoS data on the kaon multiplicities and spectra. In addition, the kaon collective flow is computed and compared with the FOPI and KaoS data. We show that the elliptic kaon flow measured recently by the KaoS Collaboration is best described by using the Brown-Rho parametrization of the kaon potential, $U_K({\rho }_0)\simeq 30\text{MeV}$.

We show that the dynamics of interacting fermions can be exactly replaced by a quantum jump theory in the many-body density matrix space. In this theory, jumps occur between densities formed of pairs of Slater determinants, $D_{\mathit{ab}}=|{\Phi }_a\rangle \langle {\Phi }_b|$, where each state evolves according to the stochastic Schrödinger equation given by O. Juillet and Ph. Chomaz [Phys. Rev. Lett. 88, 142503 (2002)]. A stochastic Liouville-von Neumann equation is derived as well as the associated. Bogolyubov-Born-Green-Kirwood-Yvon hierarchy. Due to the specific form of the many-body density along the path, the presented theory is equivalent to a stochastic theory in one-body density matrix space, in which each density matrix evolves according to its own mean-field augmented by a one-body noise. Guided by the exact reformulation, a stochastic mean-field dynamics valid in the weak coupling approximation is proposed. This theory leads to an approximate treatment of two-body effects similar to the extended time-dependent Hartree-Fock scheme. In this stochastic mean-field dynamics, statistical mixing can be directly considered and jumps occur on a coarse-grained time scale. Accordingly, numerical effort is expected to be significantly reduced for applications.

New low-spin levels in ${}^{111}\mathrm{Sb}$ have been identified following the ${\beta }^{+}$/EC decay of proton-rich ${}^{111}\mathrm{Te}$. ${}^{111}\mathrm{Te}$ was produced in the ${}^{58}\mathrm{Ni}$(${}^{56}\mathrm{Fe}$, $2\mathit{pn}$)${}^{111}\mathrm{Te}$ reaction and separated using the fragment mass analyzer at Argonne National Laboratory. γ-ray singles and $\gamma \text{−}\gamma$ coincidence spectra were collected as a function of time. Eleven new levels in ${}^{111}\mathrm{Sb}$ were identified, including levels at 487 and 881 keV that have been tentatively assigned spins and parities of $1/2^{+}$ and $3/2^{+}$, respectively. Shell-model calculations have been performed in which the single-particle $d_{3/2}$ and $s_{1/2}$ basis levels were adjusted to fit the observed positions of the low-energy $1/2^{+}$ and $3/2^{+}$ levels in ${}^{109}\mathrm{Sb}$ and ${}^{111}\mathrm{Sb}$. Good agreement for the known yrast $1/2^{+}$, $3/2^{+}$, $5/2^{+}$, $7/2^{+}$, and $9/2^{+}$ levels in ${}^{105,107,109,111}\mathrm{Sb}$ is obtained.

Lifetimes in ${}^{114}\mathrm{Te}$ were determined using the recoil distance Doppler-shift technique with a plunger device coupled to five HP Ge detectors enhanced by one Euroball cluster detector. The experiment was carried out at the Cologne FN Tandem facility using the ${}^{93}\mathrm{Nb}$(${}^{24}\mathrm{Mg},p2n$) reaction at 90 MeV. The differential decay curve method in coincidence mode was employed to derive lifetimes for seven excited states, whereas the lifetime of an isomeric state was obtained in singles mode. The resulting $E2$ transition probabilities are shown to be very anomalous in comparison with the vibrational energy spacings of the ground-state band.

Recent interest in symmetries at a critical point of phase transitions in nuclei prompts a revisit to the fermion monopole and quadrupole pairing model. This model has an exactly solvable symmetry limit that is transitional between spherical nuclei and γ-unstable deformed nuclei. The eigenenergies, eigenfunctions, pairing strength, and quadrupole transtion rates in this limit are derived. Comparison with empirical quadrupole transition rates suggest that the Xe isotopes may have this symmetry.

The neutron pairing correlation and the soft dipole excitation in medium mass nuclei near the drip line are investigated from the viewpoint of the di-neutron correlation. Numerical analyses based on the coordinate-space Hartree-Fock-Bogoliubov method and the continuum quasiparticle random phase approximation are performed for even-even ${}^{18-24}\mathrm{O},{}^{50-58}\mathrm{Ca}$, and ${}^{80-86}\mathrm{Ni}$. A clear signature of the di-neutron correlation is found in the ground state; two neutrons are correlated at short relative distances $\lesssim 2$ fm with large probability $~50\%$. The soft dipole excitation is influenced strongly by the neutron pairing correlation, and it accompanies a large transition density for pair motion of neutrons. This behavior originates from a coherent superposition of two-quasiparticle configurations $[l\times (l+1)]{}_{L=1}$ consisting of continuum states with high orbital angular momenta l reaching an order of $l~10$. It suggests that the soft dipole excitation under the influence of neutron pairing is characterized by the motion of di-neutron in the nuclear exterior against the remaining $A-2$ subsystem. Sensitivity to the density dependence of the effective pair force is discussed.

Microsecond isomers of neutron-rich nuclei in masses $A=96$ and 98 were reinvestigated at the Institut Laue-Langevin reactor (Grenoble). These nuclei were produced by thermal-neutron induced fission of ${}^{241}\mathrm{Pu}$. The detection is based on the time correlation between fission fragments selected by the Lohengrin mass spectrometer and the γ rays and conversion electrons from the isomers. A new level scheme of ${}^{96}\mathrm{Rb}$ is proposed. We have found that the ground state and low-lying levels of this nucleus are rather spherical, and a rotational band develops at 461-keV energy. This band has properties consistent with a $\pi [4313/2]\times \nu [5413/2]K=3^{-}$ Nilsson assignment and a deformation ${\beta }_2>0.28$. It is fed by a $I^{\pi }={10}^{-}$ microsecond isomer consistent with a $\pi (g_{9/2})\nu (h_{11/2})$ spherical configuration. It is interesting to note that the same unique-parity states $\pi (g_{9/2})$ and $\nu (h_{11/2})$ are present in the same nucleus in a deformed and in a spherical configuration. The neighboring odd-odd nucleus ${}^{98}\mathrm{Y}$ presents a strong analogy with ${}^{96}\mathrm{Rb}$ and is also discussed.

The spectral distribution of isovector dipole strength is computed using the time-dependent Skyrme-Hartree-Fock method with subsequent spectral analysis. The calculations are done without any imposed symmetry restriction, allowing any nuclear shape to be dealt with. The scheme is used to study the deformation dependence of giant resonances and its interplay with Landau fragmentation (owing to 1ph states). Results are shown for the chain of Nd isotopes, superdeformed ${}^{152}\mathrm{Dy}$, triaxial ${}^{188}\mathrm{Os}$, and ${}^{238}\mathrm{U}$.

We analyze data for ${}^{12}\mathrm{C}(e,e^{\text{'}}p)$ with $Q^2<2(\mathrm{GeV}/c){}^2$ using the relativistic distorted-wave impulse approximation (RDWIA) based upon Dirac-Hartree wave functions. The $1p$ normalization extracted from data for $Q^2>0.6$ (GeV/c)${}^2$ is approximately 0.87, independent of $Q^2$, which is consistent with the predicted depletion of the $1p_{3/2}$ orbital by short-range correlations. The total $1p$ and $1s$ strength for $E_m<80\mathrm{MeV}$ approaches 100% of IPSM (independent particle shell model), consistent with a continuum contribution for $30<E_m<80\mathrm{MeV}$ of about 12% of IPSM. Similarly, a scale factor of 1.12 brings RDWIA calculations into good agreement with ${}^{12}\mathrm{C}(e,e^{\text{'}}p)$ data for transparency. We also analyzed low $Q^2$ data from which a recent nonrelativistic RDWIA analysis suggested that spectroscopic factors might depend strongly upon the resolution of the probe. We find that the momentum distributions for their empirical Woods-Saxon wave functions fit to low $Q^2$ data for parallel kinematics are too narrow to reproduce data for quasiperpendicular kinematics, especially for larger $Q^2$, and are partly responsible for reducing fitted normalization factors. Although the RDWIA normalization factors for $Q^2<0.2(\mathrm{GeV}/c){}^2$ are also smaller than obtained for $Q^2>0.6(\mathrm{GeV}/c){}^2$, the effect is smaller, and we argue that it should be attributed to the effective single-nucleon current operator instead of to spectroscopic factors, which are probe-independent properties of nuclear structure. However, remediation of the failure of RDWIA calculations to reproduce low $Q^2$ data for parallel kinematics will require a more sophisticated modification of the current method than a simple multiplicative factor.

The emission of $K^{+}$ and ${\pi }^{\pm }$ mesons has been studied in the asymmetric collision system Au+C and in the inverse reaction C+Au at 1.0A GeV (and at 1.8A GeV for C+Au only) in order to extract the effective source rapidities based on their distribution in the $p_t\text{−}y$ plane. The extracted source rapidity of $K^{+}$ mesons is about $y_s/y_{\mathrm{beam}}=0.25$ at both incident energies [$y(\mathrm{Au})=0,y(C)=y_{\mathrm{beam}}$]. This corresponds to a reaction volume consisting of the C nucleus and a tube cut out of the Au nucleus. In clear contrast, the source rapidities of ${\pi }^{\pm }$ mesons vary from $y_s/y_{\mathrm{beam}}=0.5$ in peripheral collisions (corresponding to NN interactions) to about $y_s/y_{\mathrm{beam}}<0.33$ in central reactions. The multiplicities of $K^{+}$ and π are compared to symmetric collision systems and, together with detailed transport model calculations, are used to study the sensitivity to the nuclear equation of state.