The ${}^{13}\mathrm{C}(\alpha ,n){}^{16}\mathrm{O}$ reaction is investigated in a microscopic two-cluster model with an effective interaction recently developed for transfer reactions. The wave functions are defined in the generator coordinate method. The basis includes all ${}^{13}\mathrm{C}$+α and ${}^{16}\mathrm{O}$+n channels with ${}^{13}\mathrm{C}$ and ${}^{16}\mathrm{O}$ described in the p shell. Particle-hole excitations in the sd shell are also taken into account in order to include the ${}^{16}\mathrm{O}$$(3^{-})$+n channel. The ${}^{17}\mathrm{O}$ spectroscopy is in good agreement with experiment. In particular, the width of the astrophysically relevant $1/2_2^{+}$ state is well reproduced ($\Gamma =121\text{keV}$ as compared to the experimental value $\Gamma =124\pm 12\text{keV}$). The calculation of the ${}^{13}\mathrm{C}(\alpha ,n){}^{16}\mathrm{O}$ S factor shows the importance of the $3/2_3^{+}$ resonance, and provides $S(0.2\mathrm{MeV})=2.1\times {10}^6\text{MeV}$ b, slightly lower than the NACRE recommended value ($2.5\times {10}^6\text{MeV}$ b). The same model is applied to the ${}^{16}\mathrm{O}(n,\gamma ){}^{17}\mathrm{O}$ radiative-capture reaction at thermal and astrophysical energies.

Physically more transparent formulas for measuring event-by-event dynamical mean transverse momentum fluctuations ${\sigma }^2(M_{p_t,\mathrm{dyn}})$ are derived. It turns out that ${\sigma }^2(M_{p_t,\mathrm{dyn}})$ equals the dynamical fluctuations of the event total transverse momentum divided by the square of the average sample multiplicities. It is equivalent to the dynamical fluctuations of the event average transverse momentum ${\sigma }^2(M_{p_t}){}_{\mathrm{dyn}}$ when multiplicity n is fixed and different from ${\sigma }^2(M_{p_t}){}_{\mathrm{dyn}}$ when n varies from event to event. HIJING-1.382 simulations confirm the analytical results.

We investigate the finite-size scaling exponents for the critical point at the shape-phase transition from U(5) (spherical) to O(6) (deformed γ-unstable) dynamical symmetries of the interacting boson model, making use of the Holstein-Primakoff boson expansion and the continuous unitary transformation technique. We compute exactly the leading-order correction to the ground-state energy, the gap, the expectation value of the d-boson number in the ground state and the $E2$ transition probability from the ground state to the first excited state and determine the corresponding finite-size scaling exponents.

Relativistic effects in a three-body calculation of the $\mathit{np}\to \eta d$ process are considered. Parametrizations for the $\eta N$ interaction obtained from phenomenological meson-nucleon models are probed. Relativistic effects on the range and strength of the pion exchange contribution to the reaction mechanism are seen to be large, while boost effects of the two-body interactions are negligible. The relativistic calculation confirms previous nonrelativistic results, showing that the shape of the cross section near threshold is essentially determined by the $\eta d$ final-state interaction alone. As for the region away from threshold, the relativistic pion exchange contribution is seen to dominate the other mechanisms of the reaction. It turns out that, within the relativistic reaction model, the $\mathit{np}\to \eta d$ experimental data call for a comprehensive study to find parameters of the meson-nucleon interactions which are consistent with η production, both on the nucleon as well as on the deuteron.

The scalar, vector, and tensor components of the (generalized) deuteron electric dipole polarizability are calculated, as well as their logarithmic modifications. Several of these quantities arise in the treatment of the nuclear corrections to the deuterium Lamb shift and the deuterium hyperfine structure. A variety of second-generation potential models are used, and a (subjective) error is assigned to the calculations. The zero-range approximation is used to analyze a subset of the results, and a simple relativistic version of this approximation is developed.

The isospin splitting of the nucleon mean field is derived from the Brueckner theory extended to asymmetric nuclear matter. The Argonne $V_{18}$ has been adopted as bare interaction in combination with a microscopic three-body force. The isospin splitting of the effective mass is determined from the Brueckner-Hartree-Fock self-energy: It is linear according to the Lane ansatz, such that $m_n^{*}>m_p^{*}$ for neutron-rich matter. The symmetry potential is also determined, and a comparison is made with the predictions of the Dirac-Brueckner approach and the phenomenological interactions. The theoretical predictions are also compared with the empirical parametrizations of neutron and proton optical model potentials based on the experimental nucleon-nucleus scattering and the phenomenological ones adopted in transport model simulations of heavy-ion collisions. The direct contribution of the rearrangement term due to three-body forces to the single-particle potential and symmetry potential is discussed.

Using a three-dimensional formalism that includes relativistic kinematics, the effects of negative-energy states, approximate boosts of the two-body system, and current conservation, we calculate the electromagnetic form factors of the deuteron up to $Q^2$ of 4 GeV${}^2$. This is done with a dynamical boost for two-body systems with spin. We first compute form factors in impulse approximation, but then also add an isoscalar meson-exchange current of pion range that involves the $\gamma \pi$ contact operator associated with pseudovector $\pi N$ coupling. We also consider effects of the $\rho \pi \gamma$ meson-exchange current. The experimentally measured quantities $A,B$, and $t_{20}$ are calculated over the kinematic range probed in recent Jefferson Laboratory experiments. The $\rho \pi \gamma$ meson-exchange current provides significant strength in A at large $Q^2$ and the $\gamma \pi$ contact-term exchange current shifts $t_{20}$, providing good agreement with the data from the Thomas Jefferson National Accelerator Facility. Relativistic effects and the $\gamma \pi$ meson-exchange current do not provide an explanation of the B observable, but the $\rho \pi \gamma$ current could help to provide agreement if a nonstandard value is used for the tensor $\rho N$ coupling that enters this contribution.

Using the density-dependent Hartree-Fock approximation and Skyrme forces together with the scaling method and constrained Hartree-Fock calculations, we obtain the average energies of the isoscalar giant monopole resonance. The calculations are done along several isotopic chains from the proton to the neutron drip lines. It is found that while approaching the neutron drip line, the scaled and the constrained energies decrease and the resonance width increases. Similar but smaller effects arise near the proton drip line, although only for the lighter isotopic chains. A qualitatively good agreement is found between our sum rule description and the presently existing random phase approximation results. The ability of the semiclassical approximations of the Thomas-Fermi type, which properly describe the average energy of the isoscalar giant monopole resonance for stable nuclei, to predict average properties for nuclei near the drip lines is also analyzed. We show that when $\hslash$ corrections are included, the semiclassical estimates reproduce, on average, the quantal excitation energies of the giant monopole resonance for nuclei with extreme isospin values.

The boson expansion method is applied to find the spectrum of a q-deformed harmonic oscillator. We use two different boson expansions, each of them including a deformation parameter, defined in terms of exponential and logarithmic functionals. The resulting Hamiltonians are bilinear forms of the transformed operators. Physical effects resulting from the deformation of the generators of the algebra are studied by comparing known finite-range potentials and the effective potentials obtained for each of the considered Hamiltonians.

The rotational band built on the high-K multi-quasiparticle state can be interpreted as a multi-phonon band of the precession mode, which represents the precessional rotation about the axis perpendicular to the direction of the intrinsic angular momentum. By using the axially symmetric limit of the random-phase approximation (RPA) formalism developed for the nuclear wobbling motion, we study the properties of the precession modes in ${}^{178}\mathrm{W}$: the excitation energies, $B(E2)$ and $B(M1)$ values. We show that the excitations of such a specific type of rotation can be well described by the RPA formalism, which gives new insight into the wobbling motion in the triaxial superdeformed nuclei from a microscopic viewpoint.

In thermal neutron-induced and spontaneous fission the addition of two neutrons to a neutron-even system produces only minor changes to the shape, kinetic energy, and temperature of the scission configuration. If these changes are assumed negligible and if ternary fission is associated with a statistical process then the ratio of ternary fission yields for systems differing by two atomic mass units can be used to infer a nuclear temperature. The yields of hydrogen, helium, lithium, and beryllium isotopes ejected perpendicular to the direction of the main fragments from ${}^{233,235}\mathrm{U}(n_{\mathrm{th}},f)$, ${}^{239,241}\mathrm{Pu}(n_{\mathrm{th}},f)$, and ${}^{250,252}\mathrm{Cf}$ spontaneous fission give a nuclear temperature $T=1.24\pm 0.10\text{MeV}$. The yield of polar $\alpha$ particles from ${}^{233,235}\mathrm{U}(n_{\mathrm{th}},f)$ give $T=1.13\pm 0.24\text{MeV}$. These results are in agreement with other inferred low-energy ternary fission temperatures and support the idea that both equatorial and polar ternary fission involve a statistical process where the ejected particles are in equilibrium with a heat bath with a temperature slightly hotter than 1 MeV.

An attempt to confirm production of superheavy elements in the reaction of ${}^{48}\mathrm{Ca}$ beams with actinide targets has been performed using the ${}^{238}\mathrm{U}$(${}^{48}\mathrm{Ca}$,3$n){}^{283}$112 reaction. Two ${}^{48}\mathrm{Ca}$ projectile energies were used that spanned the energy range where the largest cross sections have been reported for this reaction. No spontaneous fission events were observed. No α decay chains consistent with either reported or theoretically predicted element 112 decay properties were observed. The cross-section limits reached are significantly smaller than the recently reported cross sections.

Proton productions from proton induced reactions have been investigated for target nuclei of ${}^{12}\mathrm{C}$, ${}^{27}\mathrm{Al}$, and ${}^{93}\mathrm{Nb}$ at 300 and 392 MeV. Proton inelastic continua over a broad energy range were measured at laboratory angles from ${20}^{°}$ to ${105}^{°}$. The differential cross sections were compared with two theoretical models, the quantum molecular dynamics (QMD) and the intranuclear cascade (INC) model in terms of the multistep direct process. We demonstrated that consistencies of these models can be improved using a realistic ground state of target nucleus, and that the INC model developed presently has a fairly good consistency and a higher predictive ability than the QMD.

Within the fragmentation theory, extended to include the orientations degrees of freedom and hexadecupole deformations, for optimized orientations, the ${}^{48}\mathrm{Ca}+{}^{244}\mathrm{Pu}\to {}^{292}{114}^{*}$ reaction is shown to be a “compact” hot fusion reaction. The barrier is highest (hot fusion) and interaction radius smallest (compact), which occur for the collisions in the direction of the minor axis of the deformed reaction partner (i.e. for ${90}^{°}$ orientation of ${}^{244}\mathrm{Pu}$). In addition to the ${}^{48}\mathrm{Ca}+{}^{244}\mathrm{Pu}$ reaction valley, a number of other new reaction valleys (target-projectile combinations) are shown to arise for the “optimally oriented hot” fusion process, the ${}^{48}\mathrm{Ca}+{}^{244}\mathrm{Pu}$ being the best (lowest barrier) and ${}^{54}\mathrm{Ti}+{}^{238}\mathrm{U}$ as the next possible best reaction for forming the cold compound nucleus ${}^{292}{114}^{*}$. A similar reaction valley for ${}^{48}\mathrm{Ca}+{}^{244}\mathrm{Pu}$ is found absent in the “optimally oriented cold” fusion process.

We present the results of $\varphi$ meson production in the $K^{+}{K}^{-}$ decay channel from $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$ as measured at midrapidity by the PHENIX detector at Brookhaven National Laboratory's Relativistic Heavy Ion Collider. Precision resonance centroid and width values are extracted as a function of collision centrality. No significant variation from the Particle Data Group accepted values is observed, contrary to some model predictions. The $\varphi$ transverse mass spectra are fitted with a linear exponential function for which the derived inverse slope parameter is seen to be constant as a function of centrality. However, when these data are fitted by a hydrodynamic model the result is that the centrality-dependent freeze-out temperature and the expansion velocity values are consistent with the values previously derived from fitting identified charged hadron data. As a function of transverse momentum the collisions scaled peripheral-to-central yield ratio $R_{\mathrm{CP}}$ for the $\varphi$ is comparable to that of pions rather than that of protons. This result lends support to theoretical models that distinguish between baryons and mesons instead of particle mass for explaining the anomalous (anti) proton yield.

The results from the STAR Collaboration on directed flow ($v_1$), elliptic flow ($v_2$), and the fourth harmonic ($v_4$) in the anisotropic azimuthal distribution of particles from Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$ are summarized and compared with results from other experiments and theoretical models. Results for identified particles are presented and fit with a blast-wave model. Different anisotropic flow analysis methods are compared and nonflow effects are extracted from the data. For $v_2$, scaling with the number of constituent quarks and parton coalescence are discussed. For $v_4$, scaling with $v_2^2$ and quark coalescence are discussed.

Inclusive cross sections for pion production in proton-proton collisions are calculated for the first time based on unintegrated parton (gluon, quark, antiquark) distributions (uPDFs). We use Kwieciński uPDFs and phenomenological fragmentation functions from the literature. In addition to the $\mathit{gg}\to g$ diagram used recently for applications at RHIC we include also $gq\to q$ and $qg\to q$ diagrams. We find that the new contributions are comparable to the purely gluonic one at midrapidities and dominate in the fragmentation region. The new mechanisms are responsible for ${\pi }^{+}\text{−}{\pi }^{-}$ asymmetry. We discuss how the asymmetry depends on $x_F$ and $p_t$. Inclusive distributions in $x_F$ (or rapidity) and transverse momentum for partons and pions are shown for illustration. In contrast to the standard collinear approach, in our approach the range of applicability can be extended toward much lower transverse momenta.

The differential cross section for η production in reaction ${\pi }^{-}p\to \eta n$ has been measured over the full angular range at seven incident ${\pi }^{-}$ beam momenta from threshold to $p_{{\pi }^{-}}=747$ MeV/c using the Crystal Ball multiphoton spectrometer. The angular distributions are S wave dominated. At 10 MeV/c above threshold, a small D-wave contribution appears that interferes with the main S wave. The total η production cross section ${\sigma }^{\mathrm{tot}}$ is obtained by integration of $d\sigma /d\Omega$. Starting at threshold, ${\sigma }^{\mathrm{tot}}$ rises rapidly, as expected for S-wave-dominated production. The features of the ${\pi }^{-}p\to \eta n$ cross section are strikingly similar to those of the SU(3) flavor-related process $K^{-}p\to \eta \Lambda$. Comparison of the ${\pi }^{-}p\to \eta n$ reaction is made with η photoproduction.

Thermodynamic formulas for investigating systems with density- and/or temperature-dependent particle masses are generally derived from the fundamental derivation equality of thermodynamics. Various problems in the previous treatments are discussed and modified. Properties of strange quark matter in bulk and strangelets at both zero and finite temperature are then calculated based on the new thermodynamic formulas with a new quark mass scaling, which indicates that low-mass strangelets near β equilibrium are multiquark states with an antistrange quark, such as the pentaquark ($u^2{d}^2\overline{s}$) for baryon number 1 and the octaquark ($u^4{d}^3\overline{s}$) for dibaryon, etc.

Hyperfine intervals in light hydrogenic atoms and ions are among the most accurately measured quantities in physics. The theory of QED corrections has recently advanced to the point that uncalculated terms for hydrogenic atoms and ions are probably smaller than 0.1 parts per million (ppm), and the experiments are even more accurate. The difference of the experiments and QED theory is interpreted as the effect on the hyperfine interaction of the (finite) nuclear charge and magnetization distributions, and this difference varies from tens to hundreds of ppm. We have calculated the dominant component of the 1s hyperfine interval for deuterium, tritium, and singly ionized helium, using modern second-generation potentials to compute the nuclear component of the hyperfine splitting for the deuteron and the trinucleon systems. The calculated nuclear corrections are within 3% of the experimental values for deuterium and tritium, but are about 20% discrepant for singly ionized helium. The nuclear corrections for the trinucleon systems can be qualitatively understood by the invoking of SU(4) symmetry.