We present general arguments, based on the medium-induced radiative energy loss, to explain the presence of nontrivial angular structures within this perturbative mechanism. Simple analytical estimates of this effect are provided which are relevant to the current discussion on the interpretation of the data on two- and three-particle correlations of semihard particles at BNL's Relativistic Heavy Ion Collider.

We present a thermal and quantum-mechanical treatment of nuclear rotation using the formalism of the static path approximation plus the random-phase approximation. Naive perturbation theory fails because of the presence of zero-frequency modes resulting from dynamical symmetry breaking. Such modes lead to infrared divergences. We show that composite zero-frequency excitations are properly treated within the collective coordinate method. The resulting perturbation theory is free from infrared divergences. Without the assumption of individual random spin vectors, we derive microscopically the spin distribution of the level density. The moment of inertia is thereby related to the spin-cutoff parameter in the usual way. Explicit calculations are performed for ${}^{56}\mathrm{Fe}$; various thermal properties are discussed. In particular, we demonstrate that the increase of the moment of inertia with increasing temperature is correlated with the suppression of pairing correlations.

Using the quark gluon plasma (QGP) motivated threshold model, where all the $J/\psi$'s are suppressed above a threshold density, we have analyzed the recent PHENIX data on the participant number dependence of the nuclear modification factor for $J/\psi$'s, in Au+Au collisions, at RHIC energy, $\sqrt{s}{}_{\mathit{NN}}=200$ GeV. Centrality dependence of midrapidity $J/\psi$ suppression in Au+Au collisions are well explained in the model for threshold density $n_c\approx 3.6{\mathrm{fm}}^{-2}$. PHENIX data on $J/\psi$ suppression at forward rapidity data are not explained in the model. The analysis strongly supports deconfined matter formation in central Au+Au collisions at midrapidity. We have also analyzed the preliminary PHENIX data on $J/\psi$ suppression in Cu+Cu collisions. Cu+Cu data are not explained in the threshold model.

An experiment was performed at the Australian National University to study the ${}^9\mathrm{Be}$(${}^6\mathrm{Li}$,${}^6\mathrm{Li}$)${}^9\mathrm{Be}$${}^{*}\to \alpha +\alpha +n$ reaction. This experiment was designed to study the breakup of ${}^9\mathrm{Be}$, in an attempt to quantify the contribution played by the ${}^5\mathrm{He}+\alpha$ and ${}^8{\mathrm{Be}}^{2^{+}}+n$ channels for the low lying excited states. This information is required in order to resolve uncertainties in the $\alpha +\alpha +n\to$ ${}^9\mathrm{Be}$ reaction rate in high-energy and neutron-rich astrophysical environments such as supernovae. Angular correlation measurements have been used to deduce that the 2.429 MeV state breaks up almost exclusively via the ${}^8{\mathrm{Be}}^{2^{+}}$ channel. This method of identifying the break-up channel resolves the problem of distinguishing between the ${}^8{\mathrm{Be}}^{2^{+}}$ and ${}^5{\mathrm{He}}^{\text{g.s.}}$ channels which are kinetically identical at this excitation energy.

High-spin states in the $N=Z$ nucleus ${}^{72}\mathrm{Kr}$ have been populated in the ${}^{40}\mathrm{Ca}$(${}^{40}\mathrm{Ca}$, 2α)${}^{72}\mathrm{Kr}$ fusion-evaporation reaction at a beam energy of 165 MeV using the Gammasphere array for γ-ray detection coupled to the Microball array for charged particle detection. The previously observed bands in ${}^{72}\mathrm{Kr}$ were extended to an excitation energy of ∼24 MeV and angular momentum of 30ℏ. Using the Doppler shift attenuation method the lifetimes of high-spin states were measured for the first time. Excellent agreement between the results of calculations within the isovector mean field theory and experiment is observed both for rotational and deformation properties. No enhancement of quadrupole deformation expected in the presence of isoscalar $t=0$ $\mathit{np}$ pairing is observed. Current data do not show any evidence for the existence of the isoscalar $\mathit{np}$ pairing.

An analysis of the world's neutrino oscillation data, including sterile neutrinos, [M. Sorel, C. M. Conrad, and M. H. Shaevitz, Phys. Rev. D 70, 073004 (2004)] found a peak in the allowed region at a mass-squared difference $\Delta m^2\cong 0.9{\mathrm{eV}}^2$. We trace its origin to harmonic oscillations in the electron survival probability ${\mathcal{P}}_{\mathit{ee}}$ as a function of $L/E$, the ratio of baseline to neutrino energy, as measured in the near detector of the Bugey experiment. We find a second occurrence for $\Delta m^2\cong 1.9{\mathrm{eV}}^2$. We point out that the phenomenon of harmonic oscillations of ${\mathcal{P}}_{\mathit{ee}}$ as a function of $L/E$, as seen in the Bugey experiment, can be used to measure the mass-squared difference associated with a sterile neutrino in the range from a fraction of an ${\mathit{eV}}^2$ to several ${\mathit{eV}}^2$ (compatible with that indicated by the LSND experiment), as well as measure the amount of electron-sterile neutrino mixing. We observe that the experiment is independent, to lowest order, of the size of the reactor and suggest the possibility of a small reactor with a detector sitting at a very short baseline.

It has been known for some time that for short range potentials scattering observables can be calculated using complex coordinates. We will show that the standard uniform complex scaling can be applied to calculate the scattering amplitude even in the presence of a long range interaction. The main advantage of the application of the complex scaling to the scattering problem is that the direct imposition of the complicated scattering boundary condition can be avoided. As a result, the scattering problem can be solved using only square integrable functions. The method will be applied not only for potential scattering but for the coupled-channel reaction model. As an application we calculate the phase shifts of the charge exchange reaction ${}^3\mathrm{H}$$(p,n)$${}^3\mathrm{He}$.

We have determined the relation between the in-medium $\omega$ meson mass and quark condensate in the framework of a Nambu–Jona-Lasinio model constrained by some recent experimental data on the meson properties in nuclei. In addition to the usual four-quark interactions, we have included eight-quark terms in the Lagrangian. The parameters of this model have been determined using the meson properties in the vacuum as well as in the medium. More particularly, we have constrained both the in-medium pion decay constant to the value measured in experiments on deeply bound pionic atoms and the in-medium $\omega$ meson mass to the experimental value obtained either by the TAPS collaboration or by the E325 experiment at KEK Proton Synchrotron. Our results are compared to several scaling laws and in particular to that of G. E. Brown and M. Rho [(Phys. Rep. 398, 301 (2004)].

An exact calculation of the photodisintegration cross section of ${}^3\mathrm{H}$, ${}^3\mathrm{He}$, and ${}^4\mathrm{He}$ is performed by using as interaction the correlated Argonne V18 potential, constructed within the unitary correlation operator method ($V_{\mathrm{UCOM}}$). Calculations are carried out by using the Lorentz integral transform method in conjunction with a hyperspherical harmonics basis expansion. A comparison with other realistic potentials and with available experimental data is discussed. The $V_{\mathrm{UCOM}}$ potential leads to a description of the cross section that is very similar to that of the Argonne V18 interaction with the inclusion of the Urbana IX three-body force for photon energies $45⩽\omega ⩽120$ MeV, whereas larger differences are found close to threshold.

High-precision mass measurements of more than 30 neutron-rich nuclides around the $Z=28$ closed proton shell were performed with the triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN to address the question of a possible neutron shell closure at $N=40$. The results for ${}^{57,60,64-69}\mathrm{Ni}$ ($Z=28$), ${}^{65-74,76}\mathrm{Cu}$ ($Z=29$), and ${}^{63-65,68-78}\mathrm{Ga}$ ($Z=31$) have a relative uncertainty of the order of ${10}^{-8}$. In particular, the mass of ${}^{76}\mathrm{Cu}$ was measured for the first time. We analyze the resulting mass surface for signs of magicity, comparing the behavior of $N=40$ with that of known magic numbers and with midshell behavior. While the classic indications from the mass surface show no evidence for a shell closure at $N=40$, there is evidence for a weak—and very localized—effect for $Z=28$, consistent with findings from nuclear spectroscopy studies.

The elliptic flow of Λ hyperons has been measured by the NA49 Collaboration at the CERN-SPS in semicentral Pb+Pb collisions at $158A$ GeV. The standard method of correlating particles with the event plane was used. Measurements of $v_2$ near midrapidity are reported as a function of rapidity, centrality and transverse momentum. Elliptic flow of Λ particles increases both with the impact parameter and with the transverse momentum. It is compared with $v_2$ for pions and protons as well as with model calculations. The observation of significant elliptic flow and its mass dependence suggest strong collective behavior of the matter produced in collisions of heavy nuclei already at the SPS. Scaling properties of elliptic flow of different particle species have been tested at $158A$ GeV. The limited $p_T$ range of the data does not allow for a decisive test of the coalescence model.

We study the phase transition from two-flavor nuclear matter to quark matter. A mean field model, constructed at the quark level, is used to give the equation of state for nuclear matter, while the equation of state for color superconducting quark matter is calculated within the NJL model. It is found that at low temperature, the phase transition from nuclear to color superconducting quark matter will take place when the density is of order $2.5{\rho }_0\text{–}5{\rho }_0$. At zero density, the quark phase will appear when the temperature is larger than about 148 MeV. Within the mean field treatment, the phase transition from nuclear matter to quark matter is always first order, whereas the transition between color superconducting quark matter and normal quark matter is second order.

We report measurements of the exclusive electroproduction of $K^{+}\Lambda$ and $K^{+}{\Sigma }^0$ final states from a proton target using the Continuous Electron Beam Accelerator Facility (CEBAF) large-acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions ${\sigma }_T,{\sigma }_L,{\sigma }_{\mathit{TT}}$, and ${\sigma }_{\mathit{LT}}$ were extracted from the Φ- and ε-dependent differential cross sections taken with electron beam energies of 2.567, 4.056, and 4.247 GeV. This analysis represents the first ${\sigma }_L/{\sigma }_T$ separation with the CLAS detector, and the first measurement of the kaon electroproduction structure functions away from parallel kinematics. The data span a broad range of momentum transfers from $0.5⩽Q^2⩽2.8{\mathrm{GeV}}^2$ and invariant energy from $1.6⩽W⩽2.4$ GeV, while spanning nearly the full center-of-mass angular range of the kaon. The separated structure functions reveal clear differences between the production dynamics for the Λ and ${\Sigma }^0$ hyperons. These results provide an unprecedented data sample with which to constrain current and future models for the associated production of strangeness, which will allow for a better understanding of the underlying resonant and nonresonant contributions to hyperon production.

The cross section and several spin-dependent observables have been measured with high precision for the reaction $\mathrm{H}(\overrightarrow{d},\overrightarrow{p})d$ at 90 MeV/nucleon. Several calculations were performed based either purely on two-nucleon potentials or also including three-nucleon potentials (3NP). The cross sections are consistent with all calculations including 3NPs. However, no single calculation reproduces the analyzing powers and spin-transfer coefficients, although some spin observables are reproduced to various degrees by the different calculations. A good understanding of the spin structure of 3NP is still lacking.

Nuclear “pasta,” nonspherical nuclei in dense matter, is predicted to occur in collapsing supernova cores. We show how pasta phases affect the neutrino transport cross section via weak neutral current using several nuclear models. This is the first calculation of the neutrino opacity of the phases with rod-like and slab-like nuclei taking account of finite temperature effects, which are well described by the quantum molecular dynamics. We also show that pasta phases can occupy 10–20% of the mass of supernova cores in the later stage of the collapse.

The α-transitions $(▵\ell =0)$ to ground and first excited $0^{+}$ states in neutron deficient Pb and Po isotopes are systematically analyzed by the density-dependent cluster model. The magnitude of nuclear deformation of the coexisting $0_1^{+}$ and $0_2^{+}$ states is extracted directly from the experimental α-decay energies and half-lives. The phenomenon of shape coexistence around the $Z=82$ shell closure is clearly demonstrated in our present analysis. The obtained deformation values from Rn → Po → Pb decay chains are generally consistent with both the available experimental and theoretical studies.

The staggering factor $S_4$ in the quasi-γ band was used for the first time as a signature of the E(5) symmetry. This observable, together with the $R_{4/2}$ ratio is used to find E(5) type nuclei in the $Z=28\text{–}50$ and $Z=50\text{–}82$ shells. An E(5) candidate is found to be ${}^{64}\mathrm{Zn}$. Low-spin states in ${}^{64}\mathrm{Zn}$ populated in the $\epsilon /{\beta }^{+}$ decay of ${}^{64}\mathrm{Ga}$, produced in the ${}^{54}\mathrm{Fe}$(${}^{12}\mathrm{C}$,$\mathit{pn}$)${}^{64}\mathrm{Ga}$, were studied through off-beam γ-ray spectroscopy. The decay scheme of ${}^{64}\mathrm{Zn}$ is found to be reasonably close to the predictions of the E(5) critical point symmetry. The structure of the excited $0^{+}$ states in ${}^{64}\mathrm{Zn}$ and their behavior in the Zn isotopic chain is discussed.

We discuss effects of the electron plasma on the charged-current neutrino-nucleus reaction $({\nu }_e,e^{-})$ in a core-collapse supernova environment. We first discuss the electron screening effect on the final state interaction between the outgoing electron and the daughter nucleus. To this end, we employ a schematic surface peaked transition density and solve the Dirac equation for the outgoing electron with the screened Coulomb potential obtained with the Thomas-Fermi approximation. In addition to the screening effect, we also discuss the Pauli blocking effect due to the environmental electrons on the spectrum of the outgoing electron. We find that both effects hinder the cross section of the charged-current reaction, especially at low incident energies.

The experimental study of the unresolved rotational bands, forming ridge structures in $\gamma \text{−}\gamma$ spectra, has been performed on the superdeformed nucleus ${}^{151}\mathrm{Tb}$. γ transitions from the reaction ${}^{27}\mathrm{Al}$, at 155 MeV, on ${}^{130}\mathrm{Te}$ were measured with EUROBALL IV in high fold coincidence. The analysis of the intensities and count fluctuations of the ridge structures shows the existence of $\approx 30$ discrete rotational bands of superdeformed nature, half of which is in direct coincidence with the superdeformed yrast band. A comparison with band mixing model predictions and with a previous work on the superdeformed nucleus ${}^{143}\mathrm{Eu}$ is presented.

The elastic scattering for the ${}^{6,7}\mathrm{Li}+{}^{59}\mathrm{Co}$ systems was investigated in the bombarding energy range $12\text{MeV}⩽E_{\mathrm{lab}}⩽30\text{MeV}$ by means of an analysis using the São Paulo potential, through which the behavior of the real and imaginary parts as function of the bombarding energy was established. The experimental results suggest that overall there is an evidence of the usual threshold anomaly for both systems, although for the ${}^6\mathrm{Li}+{}^{59}\mathrm{Co}$ system, an evidence of the breakup threshold anomaly could also be questioned.