We present revised ${}^7\mathrm{Be}(p,\gamma ){}^8\mathrm{B}$ $S$ factors based on our previously published measurements, using a more detailed target analysis and improved stopping powers. Extrapolating our data below the $1^{+}$ resonance to solar energies using the latest cluster model calculations of Descouvemont, we find that $S_{17}(0)=21.5\pm 0.6$(expt) $\pm$ 0.7(theor) eV b. Fitting all modern, low-energy $(p,\gamma )$ data with the same theory, we find a “best” value of $S_{17}(0)=20.9\pm 0.6$(expt) $\pm$ 0.7(theor) eV b.

The asymmetry in the angular distribution of $\mathit{np}\to d{\pi }^0$ attributable to charge symmetry breaking is calculated using heavy baryon chiral perturbation theory. Recent developments in power counting have proven successful in describing total cross sections, and we apply them to the asymmetry calculation. Reducibility in one of the leading-order diagrams is examined. We compare the updated theory with experimental results for a range of physically reasonable parameters and find overprediction for the entire range.

The energy-level structure of ${}^{22}\mathrm{O}$ with the recently identified $N=14$ subshell closure was investigated by the $\beta$ decay of ${}^{22}\mathrm{N}$ for the first time. A $\beta$-delayed-neutron, time-of-flight measurement revealed six new neutron transitions attributed to the $\beta$ decay of ${}^{22}\mathrm{N}$. One- and two-$\beta$-delayed neutron decay of ${}^{22}\mathrm{N}$, with emission probabilities of 33(3)% and 12(3)%, respectively, were observed to correspond to four new negative-parity states in ${}^{22}\mathrm{O}$. The half-life of ${}^{22}\mathrm{N}$ $\beta$ decay was determined to be 20(2) ms. Three $\gamma$-ray transitions in ${}^{22}\mathrm{O}$ and single $\gamma$ rays in ${}^{21}\mathrm{O}$ and ${}^{20}\mathrm{O}$ were observed following the $\beta$ decay of ${}^{22}\mathrm{N}$. The observation of large Gamow-Teller strength for a highly excited state in ${}^{22}\mathrm{O}$ indicates a halo structure for ${}^{22}\mathrm{N}$. A comparison of results with shell-model predictions showed overall poor agreement. The measured ${\mathrm{P}}_n$ values of ${}^{24}\mathrm{O}$ and ${}^{25}\mathrm{F}$ components of the secondary beam showed an enhancement relative to the ${\mathrm{P}}_n$ values of adjacent oxygen and fluorine isotopes, providing additional evidence for the $N=14$ closed subshell.

Experimental multidimensional joint distributions of neutrons and charged reaction products were analyzed for ${}^{136}\mathrm{Xe}\hspace{0.5em}+\hspace{0.5em}{}^{209}\mathrm{Bi}$ reactions at $E/A=28$, 40, and 62 MeV and were found to exhibit several different types of prominent correlation patterns. Some of these correlations have a simple explanation in terms of the system excitation energy and pose little challenge to most statistical decay theories. However, several other types of correlation patterns are difficult to reconcile with some, but not other, possible reaction scenarios. In this respect, correlations between the average atomic numbers of intermediate-mass fragments, on the one hand, and light particle multiplicities, on the other, are notable. This kind of multiparticle correlation provides a useful tool for probing reaction scenarios, which is different from the traditional approach of interpreting inclusive yields of individual reaction products.

The directed flow of charged hadron and identified particles has been studied in the framework of a multiphase transport (AMPT) model for ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200,130,62.4,39,17.2$, and $9.2$ GeV. The rapidity, centrality, and energy dependence of directed flow for charged particles over a wide rapidity range are presented. The AMPT model gives the correct $v_1(y)$ slope, as well as its trend as a function of energy, while it underestimates the magnitude. Within the AMPT model, the proton $v_1$ slope is found to change its sign when the energy increases to $130$ GeV—a feature that is consistent with “anti-flow.” Hadronic rescattering is found to have little effect on $v_1$ at top energies currently available at the BNL Relativistic Heavy Ion Collider (RHIC). These studies can help us to understand the collective dynamics early on in relativistic heavy-ion collisions, and they can also be served as references for the RHIC Beam Energy Scan Program.

A three-neutrino analysis of oscillation data is performed using the recent, more finely binned Super-K oscillation data, together with the CHOOZ, K2K, and MINOS data. The solar parameters ${\Delta }_{21}$ and ${\theta }_{12}$ are fixed from a recent analysis and ${\Delta }_{32}$, ${\theta }_{13}$, and ${\theta }_{23}$ are varied. We utilize the full three-neutrino oscillation probability and an exact treatment of Earth’s Mikheyev-Smirnov-Wolfenstein (MSW) effect with a castle-wall density. By including terms linear in ${\theta }_{13}$ and $\varepsilon :={\theta }_{23}-\pi /4$, we find asymmetric errors for these parameters ${\theta }_{13}=-{0.07}_{-0.11}^{+0.18}$ and $\varepsilon ={0.03}_{-0.15}^{+0.09}$. For ${\theta }_{13}$, we see that the lower bound is primarily set by the CHOOZ experiment while the upper bound is determined by the low energy $e$-like events in the Super-K atmospheric data. We find that the parameters ${\theta }_{13}$ and $\varepsilon$ are correlated—the preferred negative value of ${\theta }_{13}$ permits the preferred value of ${\theta }_{23}$ to be in the second octant, and the true value of ${\theta }_{13}$ affects the allowed region for ${\theta }_{23}$.

In this paper we discuss the fluidity of the hot and dense QCD matter created in ultrarelativistic heavy ion collisions in comparison with various other fluids and, in particular, suggest its possible supercriticality. After examining the proper way to compare nonrelativistic and relativistic fluids from both thermodynamic and hydrodynamic perspectives, we propose a new fluidity measure that shows certain universality for a remarkable diversity of critical fluids. We then demonstrate that a fluid in its supercritical regime has its fluidity considerably enhanced. This result may suggest a possible relationship between the seemingly good fluidity of the QCD matter produced in heavy ion collisions at a center-of-mass energy of $\sqrt{s}=200A$ GeV and the supercriticality of this matter with respect to the critical end point on the QCD phase diagram. Based on this observation, we predict an even better fluidity of the matter to be created in heavy ion collisions at Large Hadron Collider energies and the loss of good fluidity at certain, lower beam energy. Finally, based on our criteria, we analyze the suitability of a hydrodynamic description for the fireball evolution in heavy ion collisions at various energies.

The observation of an anomalous $J/\psi$ suppression in nucleus-nucleus collisions is one of the most important results of the Super Proton Synchrotron (SPS) heavy-ion program. An essential ingredient in this result is the determination, obtained by studying $p–A$ collisions, of effects not related with the formation of a deconfined medium. These effects are extrapolated to $A–A$ collisions, determining a reference $J/\psi$ yield that is then compared with the measurements. In this article we investigate the role of parton shadowing on the determination of such a reference, and we calculate its effect for $\mathit{In}–\mathit{In}$ and $\mathit{Pb}–\mathit{Pb}$ collisions as a function of rapidity and centrality.

We investigate the polarization transfer coefficients $C_x$ and $C_z$ for the $\overrightarrow{\gamma }p\to K^{+}\overrightarrow{\Lambda }(1520,3/2^{-})$ reaction process, in which the photon is polarized circularly and the $\Lambda (1520,3/2^{-})$ along the $x$ or $z$ axis. To this end, we employ the effective Lagrangian method at tree level and the charge-conservation form factor scheme. In addition to the Born terms, $(s,u,t_K,t_{K^{*}})$ channels and contact term, we include a nucleon resonance $D_{13}(2080)$ in the $s$ channel. We compute the $C_x$ and $C_z$ as functions of ${\theta }_K$ as well as $E_{\mathrm{c}.\mathrm{m}.}$. It turns out that the $K^{*}$-exchange and $D_{13}$ contributions are weak within the available experimental and theoretical inputs for them. In contrast, we observe that the contact-term and $K$-exchange contributions play a dominant role in determining $C_x$ and $C_z$. Especially, $K$ exchange enhances polarization transfer to the recoil ${\Lambda }^{*}$ along the $x$ axis.

We have investigated the $(n,\gamma )$ cross sections of $p$-process isotopes with the activation technique. The measurements were carried out at the Karlsruhe Van de Graaff accelerator using the ${}^7\mathrm{Li}(p,n){}^7\mathrm{Be}$ source for simulating a Maxwellian neutron distribution of $\mathit{kT}=25$ keV. Stellar cross section measurements are reported for the light $p$-process isotopes ${}^{102}\mathrm{Pd}$, ${}^{120}\mathrm{Te}$, ${}^{130,132}\mathrm{Ba}$, and ${}^{156}\mathrm{Dy}$. In a following paper the cross sections of ${}^{168}\mathrm{Yb}$, ${}^{180}\mathrm{W}$, ${}^{184}\mathrm{Os}$, ${}^{190}\mathrm{Pt}$, and ${}^{196}\mathrm{Hg}$ will be discussed. The data are extrapolated to $p$-process energies by including information from evaluated nuclear data libraries. The results are compared to standard Hauser-Feshbach models frequently used in astrophysics.

Short-lived isomers in fission fragments following bombardment of 45-MeV ${}^6\mathrm{Li}$ on ${}^{232}\mathrm{Th}$ were examined. Isomers in the $A~95,122,$ and 132 mass regions were observed. New isomeric decays were observed in ${}^{121}\mathrm{In}$ [$T_{1/2}=17(2)\hspace{0.5em}\mu$s], ${}^{123}\mathrm{In}$ ($T_{1/2}\gtrsim 100\hspace{0.5em}\mu$s), and ${}^{125}\mathrm{Sb}$ [$T_{1/2}=25(4)\hspace{0.5em}\mu$s]. These isomers are suggested to arise from $\nu (h_{11/2}\otimes d_{3/2})7^{-}$ and $\nu (h_{11/2}\otimes s_{1/2})5^{-}$ neutron core excitations coupling with the valence proton.

We present a complete systematics (excitation function, impact parameter, system size, isospin asymmetry, and equations of state dependences) of global stopping and fragment production for heavy-ion reactions in the energy range between $50$ and $1000$ MeV/nucleon in the presence of symmetry energy and an isospin-dependent cross section. It is observed that the degree of stopping depends weakly on the symmetry energy and strongly on the isospin-dependent cross section. However, the symmetry energy and isospin-dependent cross section has an effect of the order of more than $10\%$ on the emission of light charged particles (LCP’s). It means that nuclear stopping and LCP’s can be used as a tool to get the information of an isospin-dependent cross section. Interestingly, the LCP’s emission in the presence of symmetry energy is found to be highly correlated with the global stopping.

The sub-barrier excitation function of the octupole vibrational state at $2.615$ MeV in ${}^{208}\mathrm{Pb}$ is analyzed within the coupled-channels framework. It is shown that the position of the minimum in the excitation function, which is due to the destructive interference of the Coulomb and nuclear scattering amplitudes, is very sensitive to the nuclear potential for both the ground state and the octupole state. A different nuclear potential for the $3^{-}$ state may arise from changes in the matter distribution of ${}^{208}\mathrm{Pb}$ due to the particle-hole excitations. The present analysis places a strong limit on the $3^{-}$ nuclear potential diffuseness, giving a difference of only $\Delta a_0=0.011\pm 0.004$ fm between the ground state and $3^{-}$ state diffuseness.

Elastic and inelastic scattering of 240-MeV ${}^6\mathrm{Li}$ particles from ${}^{58}\mathrm{Ni}$ and ${}^{90}\mathrm{Zr}$ were measured with the multipole-dipole-multipole spectrometer from $4^{°}⩽{\theta }_{\mathrm{c}.\mathrm{m}.}⩽{43}^{°}$. The elastic scattering data were fitted with the double-folding model using the density-dependent M3Y $\mathit{NN}$ effective interaction and with a phenomenological Woods-Saxon potential. $B(E2)$ and $B(E3)$ values obtained for low-lying $2^{+}$ and $3^{-}$ states with the double-folding calculations agreed with the adopted values.

The second and fourth Fourier harmonics of the azimuthal distribution of particles, $v_2$ and $v_4$, have been measured in $\mathrm{Au}+\mathrm{Au}$ collisions at the Relativistic Heavy Ion Collider (RHIC). The harmonic $v_4$ is mainly induced from $v_2$ as a higher-order effect. However, the ratio $v_4/(v_2){}^2$ is significantly higher than predicted by hydrodynamics. Effects of partial thermalization are estimated on the basis of a transport calculation and are shown to increase $v_4/(v_2){}^2$ by a small amount. We argue that the high value of $v_4/(v_2){}^2$ seen experimentally is mostly caused by elliptic flow fluctations. However, the standard model of eccentricity fluctuations is unable to explain the large magnitude of $v_4/(v_2){}^2$ in central collisions.

We compute two-photon exchange corrections to the electromagnetic form factor of the pion, taking into account the finite size of the pion. Compared to the soft-photon approximation for the infrared-divergent contribution, which neglects hadron structure effects, the corrections are found to be $\lesssim 1\%$ for low $Q^2$ values ($Q^2<0.1$ GeV${}^2$) but increase to several percent for $Q^2\gtrsim 1$ GeV${}^2$ at extreme backward angles.

The transverse charge density of the pion is studied based on a realistic effective Lagrangian approach, where the pion is regarded as a quark-antiquark pair-bound state. Corrections from the two spin-1/2 constituent particles and from the correlation function of quark and antiquark inside the pion are addressed.

The baryon-number density formed in relativistic nuclear collisions versus the chemical potential of the freeze-out states is systematically studied on the basis of existing measurements. A remarkable power-law behavior of the baryon-number susceptibility is found at the CERN Super Proton Synchrotron, consistent with the existence of a QCD critical point at ${\mu }_{B,c}\simeq 222$ MeV, $T_c\simeq 155$ MeV. The equation of state in different asymptotic regimes of the critical region is also examined and confronted with freeze-out states in these experiments.

The $\alpha$ preformation factor and the penetration probability are carefully analyzed for heavy and superheavy even-even nuclei. The penetration probability of an $\alpha$ cluster in the parent nucleus is calculated within the WKB approximation, whereas the nuclear potential between an $\alpha$ cluster and the daughter nucleus is obtained in the frame of a double-folding model with a density-dependent nucleon-nucleon interaction, in which the zero-range exchange term is supplemented. The $\alpha$ preformation factors in different shell regions are compared. It is shown that shell effects play an important role in $\alpha$ preformation. The preformation factor can supply information on the nuclear structure, and the penetration probability mainly determines the $\alpha$-decay half-life. The results indicate that the deformed-subshell region at $N=162$ is different from that at $N=152$, and $Z=114$ and $N=184$ may lie in the closed-shell region.

Certain aspects of the recently proposed antisymmetrized $\alpha$-particle product state wave function, or THSR (Tohsaki-Horiuchi-Schuck-Röpke) $\alpha$-cluster wave function, for the description of the ground state in ${}^8\mathrm{Be}$, the Hoyle state in ${}^{12}\mathrm{C}$, and analogous states in heavier nuclei are elaborated in detail. For instance, the influence of antisymmetrization in the Hoyle state on the bosonic character of the $\alpha$ particles is studied carefully. It is shown to be weak. Bosonic aspects in Hoyle and similar states in other self-conjugate nuclei are, therefore, predominant. Another issue is the de Broglie wavelength of $\alpha$ particles in the Hoyle state, which is shown to be much larger than the inter-$\alpha$ distance. It is pointed out that the bosonic features of low-density $\alpha$ gas states have measurable consequences, one of which, enhanced multi-$\alpha$ decay properties, has likely already been detected. Consistent with experiment, the width of the proposed analog to the Hoyle state in ${}^{16}\mathrm{O}$ at the excitation energy of $E_x=15.1$ MeV is estimated to be very small ($34$ keV), lending credit to the existence of heavier Hoyle-like states. The intrinsic single-boson density matrix of a self-bound Bose system can, under physically desirable boundary conditions, be defined unambiguously. One eigenvalue then separates out, being close to the number of $\alpha$ particles in the system. Differences between Brink and THSR $\alpha$-cluster wave functions are worked out. No cluster model of the Brink type can describe the Hoyle state with a single configuration. On the contrary, many superpositions of the Brink type are necessary, implying delocalization toward an $\alpha$-product state. It is shown that single $\alpha$-particle orbits in condensates of different nuclei are almost the same. It is thus argued that $\alpha$-particle (quartet) antisymmetrized product states of the THSR type are a very promising novel and useful concept in nuclear physics.