The charge-exchange reaction ${}^{\mathrm{60}}\mathrm{N}\mathrm{i}({}^{\mathrm{13}}\mathrm{C},{}^{\mathrm{13}}\mathrm{N}){}^{\mathrm{60}}\mathrm{C}\mathrm{o}$ at $E/A=100\mathrm{M}\mathrm{e}\mathrm{V}$ has been studied to locate isovector ($\Delta T=1$) non-spin-flip ($\Delta S=0$) giant resonances. Besides the giant dipole resonance at $E_x=8.7\mathrm{M}\mathrm{e}\mathrm{V}$, another resonance has been observed at $E_x=20\mathrm{M}\mathrm{e}\mathrm{V}$ with a width of 9 MeV. Distorted-wave Born approximation analysis on the angular distribution clearly indicated the $L=2$ multipolarity, attributing the $E_x=20\mathrm{M}\mathrm{e}\mathrm{V}$ state to the giant isovector quadrupole resonance.

We report STAR results on the azimuthal anisotropy parameter $v_2$ for strange particles $K_S^0$, $\Lambda$, and $\overline{\Lambda }$ at midrapidity in $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at $\sqrt{s_{NN}}=130\mathrm{G}\mathrm{e}\mathrm{V}$ at the Relativistic Heavy Ion Collider. The value of $v_2$ as a function of transverse momentum, $p_t$, of the produced particle and collision centrality is presented for both particles up to $p_t\sim 3.0\mathrm{G}\mathrm{e}\mathrm{V}/c$. A strong $p_t$ dependence in $v_2$ is observed up to $2.0\mathrm{G}\mathrm{e}\mathrm{V}/c$. The $v_2$ measurement is compared with hydrodynamic model calculations. The physics implications of the $p_t$ integrated $v_2$ magnitude as a function of particle mass are also discussed.

Scattering of alpha particles from ${}^{\mathrm{44}}\mathrm{T}\mathrm{i}$, the lightest unstable alpha-particle nucleus above $A=40$, has been measured at backward angles. The “anomalous” order-of-magnitude enhancement that is characteristic of ${}^{\mathrm{40}}\mathrm{C}\mathrm{a}$ and other light alpha-particle nuclei is not observed. Instead, the backward yield is similar to that observed for other nuclei heavier than ${}^{\mathrm{40}}\mathrm{C}\mathrm{a}$, and is well described with average optical model parameters.

Relativistic hydrodynamic scaling or boost invariance is a particularly important hydrodynamic regime, describing collective flows of relativistic many body systems and is used in the interpretation of experiments from high-energy cosmic rays to relativistic heavy-ion collisions. We show evidence for the emergence of hydrodynamic scaling from the dynamics of relativistic quantum field theory. We consider a scalar $\lambda {\varphi }^4$ model in $1+1$ dimensions in the Hartree approximation and study the relativistic collisions of two kinks and the decay of a localized high-energy density region. We find that thermodynamic scalar isosurfaces show approximate boost invariance at high-energy densities.

In an experiment at the SISSI-LISE3 facility of GANIL, the decay of the proton drip line nucleus ${}^{\mathrm{45}}\mathrm{F}\mathrm{e}$ has been studied. Fragment-implantation events have been correlated with radioactive decay events in a $16\times 16$ pixel silicon-strip detector. The decay-energy spectrum of ${}^{\mathrm{45}}\mathrm{F}\mathrm{e}$ implants shows a distinct peak at $(1.14\pm 0.04)\mathrm{M}\mathrm{e}\mathrm{V}$ with a half-life of $T_{1/2}=({4.7}_{-1.4}^{+3.4})\mathrm{m}\mathrm{s}$. None of the events in this peak is in coincidence with $\beta$ particles. For a longer correlation interval, daughter decays of the two-proton daughter ${}^{\mathrm{43}}\mathrm{C}\mathrm{r}$ can be observed after ${}^{\mathrm{45}}\mathrm{F}\mathrm{e}$ implantation. The decay energy for ${}^{\mathrm{45}}\mathrm{F}\mathrm{e}$ agrees nicely with several theoretical predictions for two-proton radioactivity.

We report the first measurement of strange ($\Lambda$) and antistrange ($\overline{\Lambda }$) baryon production from $\sqrt{s_{NN}}=130\mathrm{G}\mathrm{e}\mathrm{V}$ $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at the Relativistic Heavy Ion Collider (RHIC). Rapidity density and transverse mass distributions at midrapidity are presented as a function of centrality. The yield of $\Lambda$ and $\overline{\Lambda }$ hyperons is found to be approximately proportional to the number of negative hadrons. The production of $\overline{\Lambda }$ hyperons relative to negative hadrons increases very rapidly with transverse momentum. The magnitude of the increase cannot be described by existing hadronic string fragmentation models alone.

We present results on the measurement of $\Lambda$ and $\overline{\Lambda }$ production in $\mathrm{A}\mathrm{u}+\mathrm{A}\mathrm{u}$ collisions at $\sqrt{s_{NN}}=130\mathrm{G}\mathrm{e}\mathrm{V}$ with the PHENIX detector at the Relativistic Heavy Ion Collider. The transverse momentum spectra were measured for minimum bias and for the 5% most central events. The $\overline{\Lambda }/\Lambda$ ratios are constant as a function of $p_T$ and the number of participants. The measured net $\Lambda$ density is significantly larger than predicted by models based on hadronic strings (e.g., HIJING) but in approximate agreement with models which include the gluon-junction mechanism.

Medium modifications of parton fragmentation provide a novel tomographic tool for the study of the hot and dense matter created in ultrarelativistic nucleus-nucleus collisions. Their quantitative analysis, however, is complicated by the strong dynamical expansion of the collision region. Here we establish for the multiple scattering induced gluon radiation spectrum a scaling law which relates medium effects in a collision of arbitrary dynamical expansion to that in an equivalent static scenario. Based on this scaling, we calculate for typical kinematical values of the RHIC and LHC heavy ion programming medium-modified fragmentation functions for collisions with realistic dynamical expansion.

Data from $\mathrm{\text{Au}}+\mathrm{\text{Au}}$ interactions at $\sqrt{s_{NN}}=130\mathrm{\text{GeV}}$, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.

The first on-line laser spectroscopy of cooled fission fragments is reported. The ${}^{\mathrm{96}\mathrm{–}\mathrm{102}}\mathrm{Z}\mathrm{r}$ ions, produced in uranium fission, were extracted and separated using an ion guide isotope separator. The ions were cooled and bunched for collinear laser spectroscopy by a gas-filled linear Paul trap. New results for nuclear mean-square charge radii, dipole, and quadrupole moments are reported across the $N=60$ shape change. The mean-square charge radii are found to be almost identical to those of the Sr isotones and previously offered modeling of the radial changes is critically reviewed.

We have studied the $({\pi }^{-},K^{+})$ reaction on a silicon target to investigate the sigma-nucleus potential. The inclusive spectrum was measured at a beam momentum of $1.2\mathrm{G}\mathrm{e}\mathrm{V}/c$ with an energy resolution of 3.3 MeV (FWHM) by employing the superconducting kaon spectrometer system. The spectrum was compared with theoretical calculations within the framework of the distorted-wave impulse approximation, which demonstrates that a strongly repulsive sigma-nucleus potential with a nonzero size of the imaginary part reproduces the observed spectrum.

The ${}^{\mathrm{2}}\mathrm{H}(e,e^{\prime }p)n$ cross section was measured in Hall A of the Thomas Jefferson National Accelerator Facility near the top of the quasielastic peak ($x_{Bj}=0.964$) at a four-momentum transfer squared, $Q^2=0.665(\mathrm{G}\mathrm{e}\mathrm{V}/c{)}^2$ ($\omega =0.368\mathrm{G}\mathrm{e}\mathrm{V}$, $W=2.057\mathrm{G}\mathrm{e}\mathrm{V}$), and for recoil momenta up to $550\mathrm{M}\mathrm{e}\mathrm{V}/c$. The measured cross section deviates by $1–2\sigma$ from a state-of-the-art calculation at low recoil momenta. At high recoil momenta the cross section is well described by the same calculation; however, in this region, final-state interactions and interaction currents are predicted to be large, and alternative choices of nucleon-nucleon potential and nucleon current operator may result in significant spread in the calculations.

The analyzing power for proton-carbon elastic scattering in the Coulomb-nuclear interference region of momentum transfer, $9.0\times {10}^{-3}<-t<4.1\times {10}^{-2}$ $(\mathrm{G}\mathrm{e}\mathrm{V}/c{)}^2$, was measured with a $21.7\mathrm{G}\mathrm{e}\mathrm{V}/c$ polarized proton beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory. The ratio of hadronic spin-flip to nonflip amplitude, $r_5$, was obtained from the analyzing power to be $\mathrm{R}\mathrm{e}{r}_5=0.088\pm 0.058$ and $\mathrm{I}\mathrm{m}{r}_5=-0.161\pm 0.226$.

A new method for evaluating spectra and correlations in the hydrodynamic approach is proposed. It is based on an analysis of the Boltzmann equations (BE) in terms of probabilities for constituent particles to escape from the interacting system. The conditions of applicability of the Cooper-Frye freeze-out prescription are considered within the method. The results are illustrated with a nonrelativistic exact solution of BE for an expanding spherical fireball as well as with approximate solutions for ellipsoidally expanding ones.

Using the method of analytic continuation in the coupling constant with a ${}^8\text{He}+n+n$ model, we investigated the ground state of ${}^{10}\text{He}$. In addition to a solution with the two valence neutrons in $p$ states ($[p_{1/2}{p}_{1/2}{]}_{0+}$), we obtained a solution with the valence neutrons in $s$ states ($[s_{1/2}{s}_{1/2}{]}_{0+}$) as the ground state. Experimentally, such a state has not yet been observed. This newly predicted state of ${}^{10}\text{He}$ with the main component of $[s_{1/2}{s}_{1/2}{]}_{0+}$ corresponds to the ground state of ${}^{11}\text{Li}$ with a halo structure.

Six-body inelastic reactions are calculated microscopically including the full six-nucleon final state interaction. The total cross sections of $\gamma +{\text{\hspace{0.17em}︀}}^6\mathrm{H}\mathrm{e}\left({\text{\hspace{0.17em}︀}}^6\mathrm{L}\mathrm{i}\right)\to X$ are considered as examples. The Lorentz integral transform method and the effective interaction approach for the hyperspherical formalism are employed. While ${\text{\hspace{0.17em}︀}}^6\mathrm{L}\mathrm{i}$ has a single broad giant resonance peak, there are two well separated peaks for ${\text{\hspace{0.17em}︀}}^6\mathrm{H}\mathrm{e}$ corresponding to the breakup of the neutron halo and the $\alpha$ core, respectively. The comparison with the few available experimental data is discussed.

The excitation function for fusion evaporation in the ${\text{\hspace{0.17em}︀}}^{60}\text{Ni}+{\text{\hspace{0.17em}︀}}^{89}\text{Y}$ system was measured over a range in cross section covering 6 orders of magnitude. The cross section exhibits an abrupt decrease at extreme sub-barrier energies. This behavior, which is also present in a few other systems found in the literature, cannot be reproduced with present models, including those based on a coupled-channels approach. Possible causes are discussed, including a dependence on the intrinsic structure of the participants.

A formalism to evaluate the resonant states produced by two particles moving outside a closed shell core is presented. It is found that long lived two-body states (including bound states) are mostly determined by either bound single-particle states or by narrow single-particle resonances. However, they can be significantly affected by the continuum part of the spectrum.

This work presents the first continuum shell-model study of weakly bound neutron-rich nuclei involving multiconfiguration mixing. For the single-particle basis, the complex-energy Berggren ensemble representing the bound single-particle states, narrow resonances, and the nonresonant continuum background is taken. Our shell-model Hamiltonian consists of a one-body finite potential and a zero-range residual two-body interaction. It is demonstrated that the residual interaction coupling to the particle continuum is important; in some cases, it can give rise to the binding of a nucleus.

Data on $\Lambda \Lambda$ hypernuclei provide a unique method to learn details about the strangeness $S=-2\mathrm{}$ sector of the baryon-baryon interaction. From the free space Bonn-Jülich potentials, determined from data on baryon-baryon scattering in the $S=0,-1\mathrm{}$ channels, we construct an interaction in the $S=-2\mathrm{}$ sector to describe the experimentally known $\Lambda \Lambda$ hypernuclei. After including short-range (Jastrow) and RPA correlations, we find masses for these $\Lambda \Lambda$ hypernuclei in a reasonable agreement with data, taking into account theoretical and experimental uncertainties. Thus, we provide a natural extension, at low energies, of the Bonn-Jülich one-boson exchange potentials to the $S=-2\mathrm{}$ channel.