Superscaling of the quasielastic cross section in charged-current neutrino-nucleus reactions at energies of a few GeV is investigated within the framework of the relativistic impulse approximation. Several approaches are used to describe final-state interactions and comparisons are made with the plane-wave approximation. Superscaling is very successful in all cases. The scaling function obtained using a relativistic mean field for the final states shows an asymmetric shape with a long tail extending towards positive values of the scaling variable, in excellent agreement with the behavior presented by the experimental scaling function.

We show that a Dirac Hamiltonian with equal scalar and vector harmonic oscillator potentials has not only a spin symmetry but a U(3) symmetry and that a Dirac Hamiltonian with scalar and vector harmonic oscillator potentials equal in magnitude but opposite in sign has not only a pseudospin symmetry but a pseudo-U(3) symmetry. We derive the generators of the symmetry for each case.

We report the result from a search for charged-current coherent pion production induced by muon neutrinos with a mean energy of 1.3 GeV. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed, and an upper limit of $0.60\times {10}^{-2}$ is set on the cross section ratio of coherent pion production to the total charged-current interaction at 90% confidence level. This is the first experimental limit for coherent charged pion production in the energy region of a few GeV.

We use the heavy-ion phase-space exploration model to discuss the origin of the bimodality in charge asymmetry observed in nuclear reactions around the Fermi energy. We show that it may be related to the important angular momentum (spin) transferred into the quasiprojectile before secondary decay. As the spin overcomes the critical value, a sudden opening of decay channels is induced and leads to a bimodal distribution for the charge asymmetry. In the model, it is not assigned to a liquid-gas phase transition but to specific instabilities in nuclei with high spin. Therefore, we propose to use these reactions to study instabilities in rotating nuclear droplets.

The monopole effect of the tensor force is presented, exhibiting how spherical single-particle energies are shifted as protons or neutrons occupy certain orbits. An analytic relation for such shifts is shown, and their general features are explained intuitively. Single-particle levels are shown to change in a systematic and robust way, by using the $\pi +\rho$ meson exchange tensor potential, consistently with the chiral perturbation idea. Several examples are compared with experiments.

Utilizing the QCD sum rule approach to the behavior of the $\omega$ meson in nuclear matter we derive evidence for in-medium changes of particular four-quark condensates from the recent CB-TAPS experiment for the reaction $\gamma +\mathrm{A}\to {\mathrm{A}}^{\prime }+\omega (\to {\pi }^0\gamma )$ with $A=Nb$ and ${\mathrm{LH}}_2$.

Three rotational bands in ${}^{74}\mathrm{Kr}$ were studied up to (in one case one transition short of) the maximum spin $I_{\max }$ of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin $I_{\max }$. This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at $I=I_{\max }$.

The ground state neutron spectroscopic factors for 80 nuclei ranging in $Z$ from 3 to 24 have been extracted by analyzing the past measurements of the angular distributions from ($d,p$) and ($p,d$) reactions. We demonstrate an approach that provides systematic and consistent values with minimum assumptions. For the 61 nuclei that have been described by large-basis shell-model calculations, most experimental spectroscopic factors are reproduced to within 20%.

Isospin symmetry is expected for the $T_z=\pm 1\to 0$ isobaric analogous transitions in isobars with mass number $A$, where $T_z$ is the $z$ component of isospin $T$. Assuming this symmetry, strengths of analogous Gamow-Teller (GT) transitions within $A=50$ isobars were determined from a high energy-resolution $T_z=+1\to 0$, ${}^{50}\mathrm{Cr}({}^3\mathrm{He},t){}^{50}\mathrm{Mn}$ study at 0° in combination with the decay $Q$ value and lifetime from the $T_z=-1\to 0$, ${}^{50}\mathrm{Fe}\to {}^{50}\mathrm{Mn}$ $\beta$ decay. This method can be applied to other $pf$-shell nuclei and can be used to study GT strengths of astrophysical interest.

The ${}^{1}S_0$ pairing in neutron matter is studied using realistic two- and three-nucleon interactions. The auxiliary field diffusion Monte Carlo method and correlated basis function theory are employed to get quantitative and reliable estimates of the gap. The two methods are in good agreement up to the maximum gap density and both point to a slight reduction with respect to the standard BCS value. In fact, the maximum gap is about 2.5 MeV at $k_F\sim 0.8{\mathrm{fm}}^{-1}$ in BCS and 2.2–2.4 MeV at $k_F\sim 0.6{\mathrm{fm}}^{-1}$ in correlated matter. In general, the computed medium polarization effects are much smaller than those previously estimated within all theories. Truncations of Argonne $v_{8^{\prime }}$ to simpler forms give the same gaps in BCS, provided the truncated potentials have been refitted to the same $NN$ data set. The three-nucleon interaction provides an additional increase of the gap of about 0.35 MeV.

The NEMO 3 detector, which has been operating in the Fréjus underground laboratory since February 2003, is devoted to the search for neutrinoless double-beta decay ($\beta \beta 0\nu$). The half-lives of the two neutrino double-beta decay ($\beta \beta 2\nu$) have been measured for ${}^{100}\mathrm{Mo}$ and ${}^{82}\mathrm{Se}$. After 389 effective days of data collection from February 2003 until September 2004 (phase I), no evidence for neutrinoless double-beta decay was found from $\sim 7\mathrm{kg}$ of ${}^{100}\mathrm{Mo}$ and $\sim 1\mathrm{kg}$ of ${}^{82}\mathrm{Se}$. The corresponding limits are $T_{1/2}(\beta \beta 0\nu )>4.6\times {10}^{23}\mathrm{yr}$ for ${}^{100}\mathrm{Mo}$ and $T_{1/2}(\beta \beta 0\nu )>1.0\times {10}^{23}\mathrm{yr}$ for ${}^{82}\mathrm{Se}$ (90% C.L.). Depending on the nuclear matrix element calculation, the limits for the effective Majorana neutrino mass are $⟨m_{\nu }⟩<0.7–2.8\mathrm{eV}$ for ${}^{100}\mathrm{Mo}$ and $⟨m_{\nu }⟩<1.7–4.9\mathrm{eV}$ for ${}^{82}\mathrm{Se}$.

The excitation energy of the lowest-energy superdeformed band in ${}^{196}\mathrm{Pb}$ is established using the techniques of time-correlated $\gamma$-ray spectroscopy. Together with previous measurements on ${}^{192}\mathrm{Pb}$ and ${}^{194}\mathrm{Pb}$, this result allows superdeformed excitation energies, binding energies, and two-proton and two-neutron separation energies to be studied systematically, providing stringent tests for current nuclear models. The results are examined for evidence of a “superdeformed shell gap.”

The total scattering cross sections for slow neutrons with energies in the range 100 neV to 3 meV for solid ortho-${}^2\mathrm{H}_2$ at 18 and 5 K, frozen from the liquid, have been measured. The 18 K cross sections are found to be in excellent agreement with theoretical expectations and for ultracold neutrons dominated by thermal up scattering. At 5 K the total scattering cross sections are found to be dominated by the crystal defects originating in temperature induced stress but not deteriorated by temperature cycles between 5 and 10 K.

The correlation between baryon number and strangeness elucidates the nature of strongly interacting matter, such as that formed transiently in high-energy nuclear collisions. This diagnostic can be extracted theoretically from lattice QCD calculations and experimentally from event-by-event fluctuations. The analysis of present lattice results above the critical temperature severely limits the presence of $q\overline{q}$ bound states, thus supporting a picture of independent (quasi)quarks.

We calculate the effects on the elastic electron-proton scattering cross section of the two-photon exchange contribution with an intermediate $\Delta$ resonance. The $\Delta$ two-photon exchange contribution is found to be smaller in magnitude than the previously evaluated nucleon contribution, with an opposite sign at backward scattering angles. The sum of the nucleon and $\Delta$ two-photon exchange corrections has an angular dependence compatible with both the polarization-transfer and the Rosenbluth methods of measuring the nucleon electromagnetic form factors.

Low energy $\overline{K}N$ interactions are studied within unitary chiral perturbation theory at next-to-leading order with ten coupled channels. We pay special attention to the recent precise determination of the strong shift and width of the kaonic hydrogen $1s$ state by the DEAR Collaboration that has challenged our theoretical understanding of this sector of strong interactions. We typically find two classes of solutions, both of them reproducing previous data, that either can or cannot accommodate the DEAR measurements. The former class has not been previously discussed.

The reactions ${}^4\mathrm{He}(e,e^{\prime }p{}^3\mathrm{He}){\pi }^{-}$ and ${}^4\mathrm{He}(e,e^{\prime }p{}^3\mathrm{He}){\pi }^0$ were studied simultaneously, and for the first time, in a large kinematical domain including the $\Delta$-resonance region. This was achieved by detecting the recoiling ${}^3\mathrm{He}$ and ${}^3\mathrm{H}$ nuclei instead of the emitted pions. The dependences of the cross section on the recoil momentum $p_{\mathrm{rec}}$, the invariant mass $W_{\pi \mathrm{N}}$, and the direction ${\theta }_{\pi ,{\mathrm{q}}^{\prime }}$ and ${\varphi }_{\pi ,{\mathrm{q}}^{\prime }}$ of the produced pion, are globally well described by the results of (quasifree) distorted-wave impulse approximation calculations. However, in the $\Delta$-resonance region there are clear discrepancies, which point to medium modifications of the $\Delta$ in ${}^4\mathrm{He}$.

Three precise measurements for elastic $pd$ scattering at $135\mathrm{MeV}/A$ have been performed with the three different experimental setups. The cross sections are described well by the theoretical predictions based on modern nucleon-nucleon forces combined with three-nucleon forces. Relativistic Faddeev calculations show that relativistic effects are restricted to backward angles. This result supports the two measurements recently reported by RIKEN and contradicts the KVI data.

We present a novel nonextensive generalization of the Boltzmann equation. We investigate the evolution of the one-particle distribution in this framework. The stationary solution is exponential in a nonlinear function of the original energy. The total energy is composed using a general, associative nonextensive rule. We propose that for describing the hadronization of quark matter such rules may apply.

The fission probability $P_{\mathrm{f}}$ of highly excited targetlike nuclei produced in reactions of 2.5 GeV protons on Au, Bi, and U was studied as a function of excitation energy $E^{*}$ whereby $E^{*}$ is deduced eventwise from the multiplicity of evaporated light particles. At the highest $E^{*}$ of 1000 MeV $P_{\mathrm{f}}$ amounts to $\approx 30\%$ with all 3 target nuclei irrespective of the initial fissility. Statistical-model calculations satisfactorily reproduce the observed evolution of $P_{\mathrm{f}}$ with $E^{*}$—provided that no extra transient delay is introduced. Fission thus is decided upon very fast and early in the long deexcitation chain towards scission which comprises as much as $\approx 80\%$ of all evaporated alpha particles.