Relativistic Faddeev equations for three-body scattering at arbitrary energies are formulated in momentum space and in first order in the two-body transition operator directly solved in terms of momentum vectors without employing a partial wave decomposition. Relativistic invariance is incorporated within the framework of Poincaré invariant quantum mechanics and presented in some detail. Based on a Malfliet-Tjon-type interaction, observables for elastic and breakup scattering are calculated up to projectile energies of 1 GeV. The influence of kinematic and dynamic relativistic effects on those observables is systematically studied. Approximations to the two-body interaction embedded in the three-particle space are compared to the exact treatment.

The symplectic Sp$(3,\mathbb{R})$ symmetry of eigenstates for the ${}^{16}\mathrm{O}$ ground state and the $0_{\mathrm{gs}}^{+}$ and lowest $2^{+}$ and $4^{+}$ configurations of ${}^{12}\mathrm{C}$ that are determined within the framework of the no-core shell model with the JISP16 realistic interaction is examined. These states are found to project at the 80–85% level onto a few 0-particle-0-hole symplectic representations, including the most deformed configuration. The corresponding symplectic space spans 0-particle-0-hole nuclear configurations together with single- and multiparticle excitations. The results are nearly independent of the harmonic oscillator strength and whether the bare or renormalized effective interactions are used in the analysis. The outcome points to the relevance of a symplectic no-core shell model and reaffirms the Elliott SU(3) model on which the symplectic scheme is built.

In the light of renewed interest in experiments on two-particle transfer reactions, we study the evolution of the transfer spectroscopic intensities as a possible signature of shape-phase transitions. The study is carried out considering chains of even-even nuclei displaying changes in shape, such as from sphericity to axial-symmetric deformed or from sphericity to deformed γ-unstable nuclei. The evolution of the structure of these nuclei is described in terms of the interacting boson model. In correspondence to the critical points characterizing the phase transitions, the ground-to-ground two-particle transfer matrix elements display a rapid discontinuity, with a corresponding increase in the transition to the excited $0^{+}$ states. Simple formulas are given using the intrinsic-frame formalism.

The role of nuclear deformation in the photoabsorption cross section in the tail region of the electric giant dipole resonance (GDR) is studied in terms of a deformed oscillator model and a Nilsson-plus-random-phase-approximation model. It is found within the framework of these approaches that extra electric dipole strength is generated at energies below the GDR maximum if the nuclear system is spatially deformed. This is important in the prediction of stellar photodisintegration rates, knowing that an extra strength can affect these rates even below the particle separation energies through the so-called γ process. Because the nuclear deformation is governed by shell effects, this extra strength does not directly correlate with the neutron excess.

Cross sections are calculated for neutrino scattering off heavy nuclei at energies below 50 MeV. The theory of Fermi liquid is applied to estimate the rate of neutrino-nucleon elastic and inelastic scattering in a nuclear medium in terms of dynamic form factors. The cross sections, obtained here in a rather simple way, are in agreement with the results of the other much more sophisticated nuclear models. A background rate from the solar neutrino interactions within a large Ga detector is estimated in the above-mentioned approach. The knowledge of the rate is in particular rather important for new-generation large-scale neutrino experiments.

Three-body decays of resonant states are studied using integral formulas for decay widths. The theoretical approach with a simplified Hamiltonian allows semianalytical treatment of the problem. The model is applied to decays of the first excited $3/2^{-}$ state of ${}^{17}\mathrm{Ne}$ and the $3/2^{-}$ ground state of ${}^{45}\mathrm{Fe}$. The convergence of three-body hyperspherical model calculations to the exact result for widths and energy distributions are studied. The theoretical results for ${}^{17}\mathrm{Ne}$ and ${}^{45}\mathrm{Fe}$ decays are updated, and uncertainties of the derived values are discussed in detail. Correlations for the decay of the ${}^{17}\mathrm{Ne}$ $3/2^{-}$ state are also studied.

We derive quasiclassical expressions for the three-body decay width and define the “preexponential” coefficients for them. The derivation is based on the integral formulas for the three-body width obtained in the semianalytical approach with simplified three-body Hamiltonian [L.V. Grigorenko and M.V. Zhukov, Phys. Rev. C 76, 014008 (2007)]. The model is applied to the decays of the first excited $3/2^{-}$ state of ${}^{17}\mathrm{Ne}$ and the $3/2^{-}$ ground state of ${}^{45}\mathrm{Fe}$. Various qualitative aspects of the model and relations with the other simplified approaches to the three-body decays are discussed.

We use a weak-coupling procedure and results of a shell-model calculation to compute the two-proton separation energy of ${}^{19}\mathrm{Mg}$. Our result is at the upper end of the previous range, but ${}^{19}\mathrm{Mg}$ is still bound for single proton decay to ${}^{18}\mathrm{Na}$. We also calculate the $2p$ decay width.

The excitation-energy region up to 23 MeV in ${}^{58}\mathrm{Ni}$ has been investigated with the ($\overrightarrow{p},{\overrightarrow{p}}^{\text{'}})$ reaction at an incident energy of 172 MeV and forward angles favoring the excitation of the spin-dipole mode in the continuum. The measured cross sections, spin-flip cross sections, and spin-flip probabilities are compared to microscopic reaction-model calculations using various effective projectile-target interactions. The nuclear structure input, which takes into account one-particle one-hole (1p1h) as well as two-particle-two hole (2p2h) excitations, allows for a reasonable description of the continuum region well above the particle-decay thresholds. However, considerable problems remain in the description of spin-flip resonances at lower excitation energies, which cannot be explained by a quenching of the spin-isospin interaction.

The energy and angular dependence of double differential cross sections $d^2\sigma /d\Omega \mathit{dE}$ was measured for reactions induced by 2.5 GeV protons on Au target with isotopic identification of light products (H, He, Li, Be, and B) and with elemental identification of heavier intermediate mass fragments (C, N, O, F, Ne, Na, Mg, and Al). It was found that two different reaction mechanisms give comparable contributions to the cross sections. The intranuclear cascade of nucleon-nucleon collisions followed by evaporation from an equilibrated residuum describes the low energy part of the energy distributions whereas another reaction mechanism is responsible for the high energy part of the spectra of composite particles. A phenomenological model description of the differential cross sections by isotropic emission from two moving sources led to a very good description of all measured data. Values of the extracted parameters of the emitting sources are compatible with the hypothesis claiming that high energy particles emerge from preequilibrium processes consisting in a breakup of the target into three groups of nucleons; small, fast, and hot fireball of $\sim 8$ nucleons, and two larger, excited prefragments, which emit light charged particles and intermediate mass fragments. The smaller of them contains $\sim 20$ nucleons and moves with a velocity larger than the CM velocity of the proton projectile and the target. The heavier prefragment behaves similarly as the heavy residuum of the intranuclear cascade of nucleon-nucleon collisions.

We address two issues in the thermodynamic model for nuclear disassembly. Surprisingly large differences in results for specific heat were seen in predictions from the canonical and grand canonical ensembles when the nuclear system passes from liquid-gas coexistence to the pure gas phase. We are able to pinpoint and understand the reasons for such and other discrepancies when they appear. There is a subtle but important difference in the physics addressed in the two models. In particular if we reformulate the parameters in the canonical model to better approximate the physics addressed in the grand canonical model, calculations for observables converge. Next we turn to the issue of bimodality in the probability distribution of the largest fragment in both canonical and grand canonical ensembles. We demonstrate that this distribution is very closely related to average multiplicities. The relationship of the bimodal distribution to phase transition is discussed.

Faddeev multiple scattering calculations are performed for $p$-${}^{11}\mathrm{Be}$ at 100, 150, 200 MeV incident energies, and compared with full calculations where the series is calculated using Padé summation. We show that single scattering approximation overestimates the cross section at small angles, and that higher order effects are important at these intermediate energies. One needs to go beyond double scattering and include third order terms that are absent in Glauber multiple scattering formulations. This is evidence of the breakdown of the Glauber scattering framework at these energies. We also show that rescattering within the halo nucleus gives the dominant contribution to these third order terms. We point out that it is crucial to use a realistic $\mathit{NN}$ interaction in any meaningful scattering calculation, particularly at these energies.

The reaction $\mathit{ep}\to e^{\text{'}}{K}^{+}\Lambda$ was investigated using a tree-level effective Lagrangian model with coupling parameters fit to empirical cross sections for the reaction $\gamma p\to K^{+}\Lambda$. The model incorporates both spin $\frac{1}{2}$ and spin $\frac{3}{2}$ resonances in the $s$ and $u$ channels, as well as $K(892)$ and $K(1270)$ resonances in the $t$ channel. Results for the electroproduction cross sections were obtained with four different photoproduction fits, which yield roughly equivalent descriptions of the empirical photoproduction cross sections but which vary in their predictions for photoproduction polarization observables. Electromagnetic form factors are incorporated in a manner similar to previous calculations except that a multiplicative factor is introduced into the masses associated with the $s$- and $u$-channel transition form factors so that the sensitivity of the calculated cross sections to these form factors can be studied. Results are presented for the unpolarized differential cross section in a variety of kinematical situations and for particular contributions to the cross section in one particular kinematic situation. The sensitivity of the results to both the photoproduction fit employed and to the transition form factors depends to some extent on the kinematics, but in general, the calculated cross sections are more sensitive to the transition form factors than to the photoproduction fit. Our results suggest that electroproduction data, in conjunction with a reaction model that quantitatively fits the photoproduction data, may provide significant constraints on the electromagnetic form factors associated with resonance excitation.

Measurements of angular correlations of hadrons with a (semi)hard trigger hadron in heavy-ion collisions at RHIC show large angular structures opposite to the trigger which were a priori unexpected. These away side large angle correlations were first observed in two-particle correlations [S. S. Adler et al. (PHENIX Collaboration), Phys. Rev. Lett. 97, 052301 (2006) and J. Adams et al. (STAR Collaboration), Phys. Rev. Lett. 95, 152301 (2005)] and have recently also been investigated in three-particle correlation measurements [J. G. Ulery (STAR Collaboration), Nucl. Phys. A774, 581 (2006) and F. Wang, arXiv:nucl-ex/0610027]. We show that the correlation signal can be understood in terms of sonic shockwaves (‘Mach cones’) excited by hard partons supersonically traversing the medium. The propagation of such shocks through the medium evolution is treated in a Monte Carlo (MC) framework [T. Renk and J. Ruppert, Phys. Rev. C 73, 011901(R) (2006) and Phys. Lett. B646, 19 (2007)]. We demonstrate that two- and especially three-particle correlations offer nontrivial insight into the medium-averaged speed of sound and the evolution of flow. Our findings imply that the assumption of “deflected jets” is not necessary to account for the observed correlations.

Relativistic nonideal fluid dynamics is formulated in $3+1$ space-time dimensions. The equations governing dissipative relativistic hydrodynamics are given in terms of the time and three-space quantities which correspond to those familiar from nonrelativistic physics. Dissipation is accounted for by applying the causal theory of relativistic dissipative fluid dynamics. As a special case, we consider a fluid without viscous/heat couplings in the causal system of transport/relaxation equations. For the study of physical systems, we consider pure ($1+1$)-dimensional expansion in planar geometry, ($1+1$)-dimensional spherically symmetric (fireball) expansion, ($1+1$)-dimensional cylindrically symmetric expansion, and a ($2+1$)-dimensional expansion with cylindrical symmetry in the transverse plane (firebarrel expansion). The transport/relaxation equations are given in terms of the spatial components of the dissipative fluxes, since these are not independent. The choice for the independent components is analogous to the nonrelativistic equations.

In the causal theory of relativistic dissipative fluid dynamics, there are conditions on the equation of state and other thermodynamic properties such as the second-order coefficients of a fluid that need to be satisfied to guarantee that the fluid perturbations propagate causally and obey hyperbolic equations. The second-order coefficients in the causal theory, which are the relaxation times for the dissipative degrees of freedom and coupling constants between different forms of dissipation (relaxation lengths), are presented for partonic and hadronic systems. These coefficients involves relativistic thermodynamic integrals. The integrals are presented for general case and also for different regimes in the temperature-chemical potential plane. It is shown that for a given equation of state these second-order coefficients are not additional parameters but they are determined by the equation of state. We also present the prescription on the calculation of the freeze-out particle spectra from the dynamics of relativistic nonideal fluids.

Charge-changing and fragment production cross sections at $0°$ have been obtained for interactions of 290 and 400 MeV/nucleon carbon beams with C, CH${}_2$, Al, Cu, Sn, and Pb targets. These beams are relevant to cancer therapy, space radiation, and the production of radioactive beams. We compare these results against previously published results using C and CH${}_2$ targets at similar beam energies. Because of ambiguities arising from the presence of multiple fragments on many events, the previous publications reported only cross sections for B and Be fragments. In this work, we have extracted cross sections for all fragment species, using data obtained at three distinct values of angular acceptance, supplemented by data taken with the detector stack placed off the beam axis. A simulation of the experiment with the particle and heavy ion transport system (PHITS) Monte Carlo model shows fair agreement with the data obtained with the large-acceptance detectors, but agreement is poor at small acceptance. The measured cross sections are also compared with the predictions of the one-dimensional cross section models EPAX2 and NUCFRG2; the latter is presently used in NASA's space radiation transport calculations. Though PHITS and NUCFRG2 reproduce the charge-changing cross sections with reasonable accuracy, none of the models is able to accurately predict the fragment cross sections for all fragment species and target materials.

The study of color transparency (CT) in elastic electroproduction of vector mesons off nuclei encounters the problem of the onset of coherence length (CL) effects. The problem of CT-CL separation arises especially at medium energies, corresponding to the HERMES experiment, when the coherence length is of the order of the nuclear radius $R_A$. Only at asymptotic high energies, corresponding to large CL, $l_c\gg R_A$, can the CT-CL mixing be eliminated. On the other hand, the net CT effects can be studied in the kinematic range accessible by the experiment at the Continuous Electron Beam Accelerator Facility's large acceptance spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility, since in that case the CL is much smaller than the nuclear radius. Using light-cone QCD dipole formalism, we investigate manifestations of CT effects in the electroproduction of vector mesons. Motivated by expected data from the CLAS experiment, we predict the $A$ and $Q^2$ dependence of nuclear transparency for ${\rho }^0$ mesons produced incoherently off nuclei. We demonstrate that in the CLAS kinematic region, the CL effects are weak enough to keep the photon energy at such values as to obtain maximal photon virtualities keeping optimal statistics of the data. This has a clear advantage over a standard investigation of net CT effects fixing CL.

In this Brief Report we extract the longitudinal and transverse response functions from exclusive $(e,e^{\text{'}}p)$ cross sections at fixed squared four-momentum transfer $Q^2$ in the quasielastic region. They are extracted in parallel kinematics by applying the Rosenbluth separation to the $(e,e^{\text{'}}p)$ reactions. The distorted Coulomb effects are also taken into account on each extracted response functions. The Coulomb effects in the response functions are different from those of the corresponding cross sections.

Elastic scattering of identical nuclei results in oscillatory Mott scattering. The separation of the peaks is perturbed by the presence of the nuclear potential. Near-barrier measurements of Mott scattering of ${}^{58}\mathrm{Ni}$ from ${}^{58}\mathrm{Ni}$ have been made to obtain information on the diffuseness of the nuclear potential, giving a diffuseness parameter of 0.62±0.04 fm.