The correlation function of two identical particles—pions or kaons—interacting via Coulomb potential is computed. The particles are emitted from an anisotropic particle's source of finite lifetime. In the case of pions, the effect of halo is taken into account as an additional particle's source of large spatial extension. The relativistic effects are discussed in detail. The Bowler-Sinyukov procedure to remove the Coulomb interaction is carefully tested. In the absence of halo the procedure is shown to work very well even for an extremely anisotropic source. When the halo is taken into account the free correlation function, which is extracted by means of the Bowler-Sinyukov procedure, is distorted at small relative momenta but the source parameters are still correctly reproduced.

The elastic energy loss encountered by jets produced in deep-inelastic scattering (DIS) off a large nucleus is studied in the collinear limit. In close analogy to the case of (nonradiative) transverse momentum broadening, which is dependent on the medium transport coefficient $\widehat{q}$, a class of medium enhanced higher twist operators which contribute to the nonradiative loss of the forward light-cone momentum of the jet ($q^{-}$) are identified and the leading correction in the limit of asymptotically high $q^{-}$ is isolated. Based on these operator products, a new transport coefficient $\widehat{e}$ is motivated which quantifies the energy loss per unit length encountered by the hard jet. These operator products are then computed, explicitly, in the case of a similar hard jet traversing a deconfined quark-gluon plasma (QGP) in the hard-thermal-loop (HTL) approximation. This is followed by an evaluation of subleading contributions which are suppressed by the inverse light-cone momentum $q^{-}$, which yields the longitudinal “straggling,” i.e., a slight change in light cone momentum due to the Brownian propagation through a medium with a fluctuating color field.

We calculate neutrino processes involving two nucleons at subnuclear densities using chiral effective field theory. Shorter range noncentral forces reduce the neutrino rates significantly compared with the one-pion exchange approximation currently used in supernova simulations. For densities $\rho <{10}^{14}\hspace{0.5em}\mathrm{g}\hspace{0.5em}{\mathrm{cm}}^{-3}$, we find that neutrino rates are well constrained by nuclear interactions and nucleon-nucleon scattering data. As an application, we calculate the mean-square energy transfer in scattering of a neutrino from nucleons and find that collision processes and spin-dependent mean-field effects dominate over the energy transfer due to nucleon recoil.

The $\beta$ decay of ${}^{11}\mathrm{Li}$ is studied at the TRIUMF Isotope Separation and Acceleration (ISAC) facility using the $8\pi \hspace{0.5em}\gamma$-ray spectrometer coupled with an inner array of $20$ plastic scintillators for $\beta$ detection. Doppler-broadened line shapes resulting from the decay of the excited states in ${}^{10}\mathrm{Be}$ populated by $\beta$-delayed one-neutron emission are analyzed using Monte Carlo simulations. New $\beta$-delayed neutron decay branches are shown to contribute to the complex decay of ${}^{11}\mathrm{Li}$. The half-lives of all but one bound excited state in ${}^{10}\mathrm{Be}$ are also deduced from this work. Among them, the half-life of the $2^{-}$ state in ${}^{10}\mathrm{Be}$ is shown to be much shorter than previously thought, yielding a new experimental $B(E1)$ now well within the range of theoretical predictions and providing further evidence that the $2^{-}$ state in ${}^{10}\mathrm{Be}$ is an excited halo state. The nature of the $8.82$-MeV state in ${}^{11}\mathrm{Be}$ and its decay paths to excited states in ${}^{10}\mathrm{Be}$ are found to be consistent with the $\beta$ decay of the core proceeding through this particular state.

Excitation functions of quasi-elastic scattering at backward angles have been measured for the ${}^{6,7}\mathrm{Li}+{}^{144}\mathrm{Sm}$ systems at near-barrier energies, and fusion barrier distributions have been extracted from the first derivatives of the experimental cross sections with respect to the bombarding energies. The data have been analyzed in the framework of continuum discretized coupled-channel calculations, and the results have been obtained in terms of the influence exerted by the inclusion of different reaction channels, with emphasis on the role played by the projectile breakup.

Penning trap mass measurements of neutron-deficient Cd isotopes ${}^{99-109}\mathrm{Cd}$ have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all with relative mass uncertainties below $3·{10}^{-8}$. A new mass evaluation has been performed. The mass of ${}^{99}\mathrm{Cd}$ has been determined for the first time, which extends the region of accurately known mass values toward the doubly magic nucleus ${}^{100}\mathrm{Sn}$. The implication of the results on the reaction path of the $rp$ process in stellar x-ray bursts is discussed. In particular, the uncertainty of the abundance and the overproduction created by the $rp$-process for the mass $A=99$ are demonstrated by reducing the uncertainty of the proton-separation energy of ${}^{100}\mathrm{In}$$S_p$(${}^{100}\mathrm{In}$) by a factor of $2.5$.

Binary fission induced by 140 MeV $\alpha$ particles has been measured for ${}^{\mathrm{nat}}\mathrm{Ag}$, ${}^{139}\mathrm{La}$, ${}^{165}\mathrm{Ho}$, and ${}^{197}\mathrm{Au}$ targets. The measured quantities are the total kinetic energies, fragment masses, and fission cross sections. The results are compared with other data and systematics. A minimum of the fission probability in the vicinity $Z^2/A=24$ is observed.

As a new and clean probe to the strongly interacting quark-gluon plasma (sQGP), we propose an azimuthal correlation of an electron and a muon that originate from the semileptonic decay of charm and bottom quarks. By solving the Langevin equation for the heavy quarks under the hydrodynamic evolution of the hot plasma, we show that substantial quenching of the away-side peak in the electron-muon correlation can be seen if the sQGP drag force acting on heavy quarks is large enough as suggested from the gauge/gravity correspondence. The effect could be detected in high-energy heavy ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider.

The triple-α-particle breakup of states in the triple-$\alpha$ continuum of ${}^{12}\mathrm{C}$ has been investigated by way of coincident detection of all three $\alpha$ particles of the breakup. The states have been fed in the $\beta$ decay of ${}^{12}\mathrm{N}$ and ${}^{12}\mathrm{B}$, and the $\alpha$ particles measured using a setup that covers all of the triple-$\alpha$ phase space. Contributions from the breakup through the ${}^8\mathrm{Be}$$(0^{+})$ ground state as well as other channels—interpreted as breakup through excited energies in ${}^8\mathrm{Be}$—have been identified. Spins and parities of ${}^{12}\mathrm{C}$ triple-$\alpha$ continuum states are deduced from the measured phase-space distributions for breakup through ${}^8\mathrm{Be}$ above the ground state by comparison to a fully symmetrized sequential $R$-matrix description of the breakup. At around $10$ MeV in ${}^{12}\mathrm{C}$, the breakup is found to be dominated by $0^{+}$ strength breaking up through the ghost of the ${}^8\mathrm{Be}$$(0^{+})$ ground state with $L=0$ angular momentum between the first emitted $\alpha$ particle and the intermediate ${}^8\mathrm{Be}$ nucleus. For ${}^{12}\mathrm{C}$ energies above the $12.7$ MeV $1^{+}$ state, however, $L=2$ breakup of a ${}^{12}\mathrm{C}$ $2^{+}$ state through the ${}^8\mathrm{Be}$$(2^{+})$ excited state dominates. Furthermore, the possibility of a $2^{+}$ excited state in the $9\text{−}12$ MeV region of ${}^{12}\mathrm{C}$ is investigated.

Based on the preformed cluster model (PCM) of Gupta and collaborators, we have extended our recent study on ground-state cluster decays to parent nuclei resulting in daughters other than spherical ${}^{208}\mathrm{Pb}$, i.e., to deformed daughters, and the very new cases of ${}^{14}\mathrm{C}$ and ${}^{15}\mathrm{N}$ decays of ${}^{223}\mathrm{Ac}$, and ${}^{34}\mathrm{Si}$ decay of ${}^{238}\mathrm{U}$, taking nuclei as spherical, quadrupole deformed (${\beta }_2$) alone, and with higher multipole deformations up to hexadecapole (${\beta }_2$, ${\beta }_3$, ${\beta }_4$) together with the “optimum” orientations of cold decay process. Except for ${}^{14}\mathrm{C}$ decays of ${}^{221}\mathrm{Fr}$, ${}^{221-224,226}\mathrm{Ra}$, and ${}^{225}\mathrm{Ac}$ where higher multipole deformations up to ${\beta }_4$ are found essential, the quadrupole deformation ${\beta }_2$ alone is found good enough to fit the experimental data. Because the PCM treats the cluster-decay process as the tunneling of a preformed cluster, the deformations and orientations of nuclei modify both the preformation probability $P_0$ and tunneling probability $P$, and hence the decay half-life, considerably.

Four-quark states may exist as colorless meson-meson molecules or compact systems with two-body colored components. We derive an analytical procedure to expand an arbitrary four-quark wave function in terms of nonorthogonal color singlet-singlet vectors. Using this expansion we develop the necessary formalism to evaluate the probability of physical components with an arbitrary four-quark wave function. Its application to characterize bound and unbound four-quark states as meson-meson, molecular, or compact systems is discussed

Background: Nucleon-nucleon ($\mathit{NN}$) bremsstrahlung processes $\mathit{NN}\gamma$ ($\mathit{nn}\gamma$, $\mathit{np}\gamma$, and $\mathit{pp}\gamma$) have been extensively investigated. Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering $\mathit{NN}\nu \overline{\nu }$ ($\mathit{nn}\nu \overline{\nu }$, $\mathit{np}\nu \overline{\nu }$, and $\mathit{pp}\nu \overline{\nu }$) have recently attracted attention in studies of neutrino emission in neutron stars. The calculated $\mathit{NN}\nu \overline{\nu }$ cross sections (or emissivities) are found to be sensitive to the two-nucleon dynamical model used in the calculations. Purpose and Method: A realistic one-boson-exchange (ROBE) model for $\mathit{NN}$ interactions is used to construct the electroweak bremsstrahlung amplitudes using the well-known nucleon electromagnetic and weak interaction vertices. The constructed $\mathit{nn}\gamma$ and $\mathit{nn}\nu \overline{\nu }$ amplitudes are investigated by applying them to calculate $\mathit{nn}\gamma$ and $\mathit{nn}\nu \overline{\nu }$ cross sections, respectively. Results: (i) The 190-MeV ROBE $\mathit{nn}\gamma$ cross sections agree well with those calculated using the TuTts amplitude, but they are in disagreement with those calculated using the Low amplitude. (ii) The calculated $\mathit{nn}\nu \overline{\nu }$ cross sections using the ROBE amplitude at the neutrino-pair energy $\omega$ $=$ 1 MeV are in quantitative agreement with those calculated by Timmermans et al. [Phys. Rev. C 65, 064007 (2002)], who used the leading-order term of the soft neutrino-pair bremsstrahlung amplitude. Conclusions: The $\mathit{nn}\gamma$ amplitude in the ROBE approach, which obeys the soft-photon theorem, has a predictive power similar to that of the TuTts amplitude. The $\mathit{nn}\nu \overline{\nu }$ amplitude in the ROBE approach, which is consistent with the soft neutrino-pair bremsstrahlung theorem, has a predictive power similar to that of the soft neutrino-pair bremsstrahlung amplitude of Timmermans et al. in the low neutrino-pair energy region.

The $g$ factors of the ${}^{17}\mathrm{N}$ and ${}^{18}\mathrm{N}$ ground states were remeasured using the $\beta$-nuclear magnetic resonance ($\beta$-NMR) technique on spin-polarized fragment beams at the LISE fragment separator at GANIL. Based on the $g$-factor results, the magnetic moments of ${}^{17}\mathrm{N}$ $(I^{\pi }=1/2^{-})$ and ${}^{18}\mathrm{N}$ $(I^{\pi }=1^{-})$ were deduced: $|\mu ($${}^{17}\mathrm{N}$$)$$|=0.3551(4)\hspace{0.5em}{\mu }_N$ and $|\mu ($${}^{18}\mathrm{N}$$)$$|=0.3273(4)\hspace{0.5em}{\mu }_N$. Both results are in good agreement with and more precise than the earlier observed values.

To search for a direct-decay signal from the isomer ${}^{229}\mathrm{Th}$${}^m$, $\alpha$-particle spectra of ${}^{229}\mathrm{Th}$${}^{m,g}$ produced from 93 mg of ${}^{233}\mathrm{U}$ have been measured by using a rapid and high-resolution $\alpha$-particle spectrometry, which can distinguish $\alpha$ lines of ${}^{229}\mathrm{Th}$${}^m$ from those of its ground state. Although $\alpha$ events were not obtained in the expected energy region for ${}^{229}\mathrm{Th}$${}^m$ with the exception of those derived from ${}^{229}\mathrm{Th}$${}^g$, we can estimate that the half-life of ${}^{229}\mathrm{Th}$${}^m$ is shorter than 2 h at $3\sigma$ confidence level under the chemical condition of chloride or hydroxide.

The ${\Delta }_3(L)$ statistic is studied as a tool to detect missing levels in the neutron resonance data where two sequences are present. These systems are problematic because there is no level repulsion, and the resonances can be too close to resolve. ${\Delta }_3(L)$ is a measure of the fluctuations in the number of levels in an interval of length $L$ on the energy axis. The method used is tested on ensembles of mixed Gaussian orthogonal ensemble spectra, with a known fraction of levels $(x\%)$ randomly depleted, and can accurately return $x$. The accuracy of the method as a function of spectrum size is established. The method is used on neutron resonance data for 11 isotopes with either $s$-wave neutrons on odd-$A$ isotopes, or $p$-wave neutrons on even-$A$ isotopes. The method compares favorably with a maximum likelihood method applied to the level spacing distribution. Nuclear data ensembles were made from 20 isotopes in total, and their ${\Delta }_3(L)$ statistics are discussed in the context of random matrix theory.

Spinodal instabilities and early growth of baryon density fluctuations in symmetric nuclear matter are investigated in the basis of the stochastic extension of the relativistic mean-field approach in the semiclassical approximation. Calculations are compared with the results of nonrelativistic calculations based on Skyrme-type effective interactions under similar conditions. A qualitative difference appears in the unstable response of the system: the system exhibits most unstable behavior at higher baryon densities around ${\rho }_b=0.4{\rho }_0$ in the relativistic approach while most unstable behavior occurs at lower baryon densities around ${\rho }_b=0.2{\rho }_0$ in the nonrelativistic calculations

Results on $\Lambda$, $\overline{\Lambda }$, and ${\Xi }^{-}$ production in centrality selected $\mathrm{Pb}+\mathrm{Pb}$ reactions at 40$A$ and $158A$ GeV and in near-central $\mathrm{C}+\mathrm{C}$ and $\mathrm{Si}+\mathrm{Si}$ reactions at $158A$ GeV are presented. Transverse mass spectra, rapidity spectra, and multiplicities in dependence of the system size are discussed. Comparisons to transport models (ultrarelativistic quantum molecular dynamics and hadron string dynamics) and to the core-corona approach are performed. Although $\Lambda$ and $\overline{\Lambda }$ production can be described by transport models reasonably well, these models do not agree with the ${\Xi }^{-}$ measurements. However, the core-corona picture fits very well the system-size dependence of $\Lambda$ and ${\Xi }^{-}$, whereas it agrees less well with the $\overline{\Lambda }$ data.

The recent assertion that shape coexistence occurs in the neutron-rich isotope ${}^{43}\mathrm{S}$ implies that a state observed at 940 keV in a previous study is a rotational excitation of the deformed ground state. Here we use results from two intermediate-energy reactions to demonstrate that this state—assigned an energy of 971 keV in the present work—is indeed a rotational state. This result strengthens the case for shape coexistence in ${}^{43}\mathrm{S}$.

We calculate the binding energy, root-mean-square radius, and quadrupole deformation parameter for the recent, possibly discovered superheavy element $Z=122$, using the axially deformed relativistic mean-field (RMF) and nonrelativistic Skyrme Hartree-Fock (SHF) formalisms. The calculation is extended to include various isotopes of $Z=122$ element, starting from $A=282$ to $A=320$. We predict highly deformed structures in the ground state for all the isotopes. A shape transition appears at about $A=290$ from a highly oblate to a large prolate shape, which may be considered as the superdeformed and hyperdeformed structures of the $Z=122$ nucleus in the mean-field approaches. The most stable isotope (largest binding energy per nucleon) is found to be ${}^{302}122$, instead of the experimentally observed ${}^{292}122$.

Within the framework of the particle-number conserving (PNC) formalism, one-quasiparticle and low-lying high-$K$ pair-broken (multiquasiparticle) bands systematically observed in Hf and Lu isotopes $(170⩽A⩽178)$ are analyzed consistently. The PNC method deals with the cranked shell model with pairing interaction, in which the Pauli blocking effects are exactly accounted for, and the pairing interaction strength is determined by the experimental odd-even difference in binding energies. With an appropriate Nilsson level scheme that best fits the experimental bandhead energies of the one-quasiparticle bands, the experimental moments of inertia (MOIs) of these one-quasiparticle and multiquasiparticle bands (including configuration and frequency dependences, signature splitting, etc.) can be well reproduced without any additional free parameter. In most cases, the PNC formalism supports the configuration assignments in earlier works. the PNC calculation also reveals that the experimental systematics of low-lying high-$K$ pair-broken bands in Hf and Lu isotopes are intimately related to the subshell effects near the Fermi surfaces of both protons and neutrons.