We carry out a combined analysis of elliptic and triangular flow data using viscous relativistic hydrodynamics. We show that these data allow us to put tight constraints on models of the early dynamics of a nucleus-nucleus collision. Specifically, the rms values of the initial ellipticity ${\varepsilon }_2$ and the initial triangularity ${\varepsilon }_3$ are constrained to lie within a narrow band for each centrality. We use these constraints as a filter for existing Monte Carlo models of initial state, and provide a simple test that can be performed on any candidate model to determine its compatibility with data.

Using the $\delta$-shell representation we present a successful fit to neutron-proton and proton-proton scattering data below the pion production threshold. A detailed overview of the theory necessary to calculate observables with this potential is presented. A new data selection process is used to obtain the largest mutually consistent data base. The analysis includes data within the years 1950 to 2013. Using 46 parameters we obtain ${\chi }^2/N_{\mathrm{data}}=1.04$ with $N_{\mathrm{data}}=6713$ including normalization data. Phase shifts with error bars are provided.

We investigate the effects of finite baryon chemical potential on the transport properties of a hadron resonance gas. We find that a hadron resonance gas with large baryon number density is closer to the ideal fluid limit than the corresponding gas with zero baryon number. This suggests that the system created at the Relativistic Heavy Ion Collider (RHIC) at lower collision energies may behave as a fluid, with an effective fluidity close to the one found at RHIC's highest energy near phase transition. This might explain why the differential elliptic flow coefficient measured at lower collisional energies at RHIC is similar to the one observed at high energies.

We study the nonperturbative renormalization of the nucleon-nucleon ($NN$) interaction at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) of chiral effective field theory. A systematic variation of the cutoff parameter is performed for values below the chiral symmetry breaking scale of about 1 GeV. The accuracy of the predictions is determined by calculating the ${\chi }^2$ for the reproduction of the $NN$ data for energy intervals below pion-production threshold. At NLO, $NN$ data are described well up to about 100 MeV laboratory energy and, at NNLO, up to about 200 MeV—with, essentially, cutoff independence for cutoffs between about 450 and 850 MeV.

We analyze the mixing nature of the low-lying scalar resonance consisting of the $\pi \pi$ composite and the elementary particle within the $\sigma$ model. A method to disentangle the mixing is formulated in the scattering theory with the concept of the two-level problem. We investigate the composite and elementary components of the $\sigma$ meson by changing a mixing parameter. We also study the dependence of the results on model parameters such as the cut-off value and the mass of the elementary $\sigma$ meson.

Proton emission from deformed nuclei near the drip line is regarded as a versatile tool in nuclear structure physics and such a study in odd-odd nuclei provides us with an excellent opportunity to understand several interesting features including the interaction between the valence proton and the valence neutron. We present a detailed formalism for a full microscopic calculation of such proton emitters, where the nuclear structure and decay aspects are taken into account exactly. This formalism is based on the nonadiabatic approach for the two quasiparticle plus rotor model, where the residual neutron-proton interactions are considered in the mean field represented by a deformed Woods-Saxon potential. We demonstrate a systematic way of unambiguously identifying several parameters involved in the calculations with the aid of the experimental data. The quality of results in the case of ${}^{180}$Ta justifies the approach which is further extended to discuss in detail the proton emission from ${}^{130}$Eu. $I^{\pi }=1^{+}$ state in ${}^{130}$Eu still remains to be the proton emitting state irrespective of the choice of several parameters. We also note that the decay widths could be quite sensitive to the residual $np$ interaction in case of proton emission from isomeric states.

A new implementation of the finite amplitude method (FAM) for the solution of the relativistic quasiparticle random-phase approximation (RQRPA) is presented, based on the relativistic Hartree-Bogoliubov (RHB) model for deformed nuclei. The numerical accuracy and stability of the FAM–RQRPA is tested in a calculation of the monopole response of ${}^{22}$O. As an illustrative example, the model is applied to a study of the evolution of monopole strength in the chain of Sm isotopes, including the splitting of the giant monopole resonance in axially deformed systems.

The low-spin level scheme of ${}^{68}$Ni was investigated following two-neutron-knockout and multinucleon-transfer reactions. The energy of the first excited state was determined to be $E_x\left(0_2^{+}\right)=1603.5\left(3\right)$ keV. Relative $B\left(E2\right)$ transition probabilities were deduced and compared with shell-model calculations using several modern effective interactions. Theory reproduces the data well, but indicates substantial mixing of multi-particle, multi-hole configurations for the lowest observed $0^{+}$ and $2^{+}$ states.

We report the exclusive photoproduction cross sections for the ${\Sigma }^0\left(1385\right)$, $\Lambda \left(1405\right)$, and $\Lambda \left(1520\right)$ in the reactions $\gamma +p\to K^{+}+Y^{*}$ using the CLAS detector for energies from near the respective production thresholds up to a center-of-mass energy $W$ of $2.85$ GeV. The differential cross sections are integrated to give the total exclusive cross sections for each hyperon. Comparisons are made to current theoretical models based on the effective-Lagrangian approach and fit to previous data. The accuracy of these models is seen to vary widely. The cross sections for the $\Lambda \left(1405\right)$ region are strikingly different for the ${\Sigma }^{+}{\pi }^{-}$, ${\Sigma }^0{\pi }^0$, and ${\Sigma }^{-}{\pi }^{+}$ decay channels, indicating the effect of isospin interference, especially at $W$ values close to the threshold.

We present calculations for symmetric nuclear matter using chiral nuclear interactions within the self-consistent Green's functions approach in the ladder approximation. Three-body forces are included via effective one-body and two-body interactions, computed from an uncorrelated average over a third particle. We discuss the effect of the three-body forces on the total energy, computed with an extended Galitskii-Migdal-Koltun sum-rule, as well as on single-particle properties. Saturation properties are substantially improved when three-body forces are included, but there is still some underlying dependence on the similarity renormalization group evolution scale.

The $\gamma p\to K^0{\Sigma }^{+}$ reaction has been measured from threshold to $E_{\gamma }=1.45$ GeV ($W_{\mathrm{CM}}=1.9$ GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. In the present experiment, this reaction was searched for in the $3{\pi }^{0}p$ final state, by assuming $K_S^0\to {\pi }^0{\pi }^0$ and ${\Sigma }^{+}\to {\pi }^{0}p$. The experimental results include total and differential cross sections as well as the polarization of the recoil hyperon. The new data significantly improve empirical knowledge about the $\gamma p\to K^0{\Sigma }^{+}$ reaction in the measured energy range. The results are compared to previous measurements and model predictions. It is demonstrated that adding the present $\gamma p\to K^0{\Sigma }^{+}$ results to existing data allowed a better description of this reaction with various models.

The nucleon resonances are investigated within a dynamical coupled-channels model of $\pi N$ and $\gamma N$ reactions up to the invariant mass $W=2$ GeV. The meson-baryon ($MB$) channels included in the calculations are $MB=$ $\pi N$, $\eta N$, $K\Lambda$, $K\Sigma$, and $\pi \pi N$ that has $\pi \Delta$, $\rho N$, and $\sigma N$ resonant components. The meson-baryon amplitudes $T_{M^{\prime }{B}^{\prime },MB}\left(W\right)$ are calculated from solving a set of coupled-channels integral equations defined by an interaction Hamiltonian consisting of (a) meson-exchange interactions $v_{M^{\prime }{B}^{\prime },MB}$ derived from phenomenological Lagrangian and (b) vertex interactions $N^{*}\to MB$ for describing the transition of a bare excited nucleon state $N^{*}$ to a meson-baryon channel $MB$.  The parameters of $v_{M^{\prime }{B}^{\prime },MB}$ are mainly constrained by the fit to the data of $\pi N\to \pi N$ in the low-energy region up to $W=1.4$ GeV. The bare masses of $N^{*}$ and the $N^{*}\to MB$ parameters are then determined in simultaneous fits to the data of $\pi N\to \pi N$ up to $W=2.3$ GeV and those of $\pi N\to \eta N,K\Lambda ,K\Sigma$ and $\gamma N\to \pi N,\eta N,K\Lambda ,K\Sigma$ up to $W=2.1$ GeV. The pole positions and residues of nucleon resonances are extracted by analytically continuing the meson-baryon amplitudes $T_{M^{\prime }{B}^{\prime },MB}\left(W\right)$ to the complex Riemann energy surface. From the extracted residues, we have determined the $N^{*}\to \pi N,\gamma N,\eta N,K\Lambda ,K\Sigma$ transition amplitudes at resonance poles. We compare the resonance pole positions from our analysis with those given by the Particle Data Group and the recent coupled-channels analyses by the Jülich and Bonn-Gatchina groups. Four results agree well only for the first $N^{*}$ in each spin-parity-isospin $(J^P,I)$ channel. For higher mass states, the number of states and their resonance positions from four results do not agree well. We discuss the possible sources of the discrepancies and the need of additional data from new hadron facilities such as the Japan Proton Accelerator Research Complex.

The operator structures that can contribute to three-nucleon forces are classified in the $1/N_c$ expansion. At leading order in $1/N_c$ a spin-flavor-independent term is present, as are the spin-flavor structures associated with the Fujita-Miyazawa three-nucleon force. Modern phenomenological three-nucleon forces are thus consistent with this $\mathcal{O}\left(N_c\right)$ leading force, corrections to which are suppressed by a power series in $1/N_c^2$. A complete basis of operators for the three-nucleon force, including all independent momentum structures, is given explicitly up to next-to-leading order in the $1/N_c$ expansion.

${}^{192}$Pt is produced solely by the slow neutron capture ($s$) nucleosynthesis process and hence an accurate ($n,\gamma$) reaction rate for this nuclide would allow its use as an important calibration point near the termination of the $s$-process nucleosynthesis flow. For this reason, we have measured neutron capture and total cross sections for ${}^{192,194,195,196,\mathrm{nat}}$Pt in the energy range from 10 eV to several hundred keV at the Oak Ridge Electron Linear Accelerator. Measurements on the other Pt isotopes were, in part, necessitated by the fact that only a relatively small ${}^{192}$Pt sample of modest enrichment was available. Astrophysical ${}^{192,194,195,196}$Pt($n,\gamma$) reaction rates, accurate to approximately 3%–5%, were calculated from these data. No accurate reaction rates have been published previously for any of these isotopes. At $s$-process temperatures, previously recommended rates are larger (by as much as 35%) and have significantly different shapes as functions of temperature than our new rates. We used our new Pt results, together with ${}^{191,193}$Ir($n,\gamma$) data, to calibrate nuclear statistical model calculations and hence obtain an improved rate for the unmeasured $s$-process branching-point isotope ${}^{192}$Ir.

Background: The pseudospin symmetry (PSS) has been studied extensively for bound states. Recently, we justified rigorously that the PSS in single-particle resonant states is exactly conserved when the attractive scalar and repulsive vector potentials of the Dirac Hamiltonian have the same magnitude but opposite sign [Phys. Rev. Lett. 109, 072501 (2012)].

Purpose: To understand more deeply the PSS in single-particle resonant states, we focus on several issues related to the exact conservation and breaking mechanism of the PSS in single-particle resonances. In particular, we are interested in how the energy and width splittings of PS partners depend on the depth of the scalar and vector potentials.

Methods: We investigate the asymptotic behaviors of radial Dirac wave functions. Spherical square-well potentials are employed in which the PSS breaking part in the Jost function can be well isolated. By examining the zeros of Jost functions corresponding to small components of the radial Dirac wave functions, general properties of the PSS are analyzed.

Results: By examining the Jost function, the occurrence of intruder orbitals is explained and it is possible to trace continuously the PS partners from the PSS limit to the case with a finite potential depth. The dependence of the PSS in resonances as well as in bound states on the potential depth is investigated systematically. We find a threshold effect in the energy splitting and an anomaly in the width splitting of pseudospin partners when the depth of the single-particle potential varies from zero to a finite value.

Conclusions: The conservation and the breaking of the PSS in resonant states and bound states share some similar properties. The appearance of intruder states can be explained by examining the zeros of Jost functions. Origins of the threshold effect in the energy splitting and the anomaly in the width splitting of PS partners, together with many other problems, are still open and should be further investigated.

We exactly solve the one-dimensional boost-invariant Boltzmann equation in the relaxation time approximation for arbitrary shear viscosity. The results are compared with the predictions of viscous and anisotropic hydrodynamics. Studying different nonequilibrium cases and comparing the exact kinetic-theory results to the second-order viscous hydrodynamics results we find that recent formulations of second-order viscous hydrodynamics agree better with the exact solution than the standard Israel-Stewart approach. Additionally, we find that, given the appropriate connection between the kinetic and anisotropic hydrodynamics relaxation times, anisotropic hydrodynamics provides a very good approximation to the exact relaxation time approximation solution.

The difference between the flow ellipticities of oppositely charged pions $\Delta v_2\equiv v_2\left[{\pi }^{-}\right]-v_2\left[{\pi }^{+}\right]$, measured recently by the STAR Collaboration at the Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) shows a linear dependence on the event charge asymmetry $A_{\pm }\equiv (N_{+}-N_{-})/(N_{+}+N_{-})\text{:}\Delta v_2\left(A_{\pm }\right)=\Delta v_2\left(0\right)+r{A}_{\pm }$ with a slope $r>0$ and a nonzero intercept $\Delta v_2\left(0\right)>0$ on the order of ${10}^{-4}$. We discuss two novel mechanisms, which could explain the nonzero value of the charged elliptic flow $\Delta v_2$ at zero charge asymmetry $A_{\pm }=0$, i.e., the nonzero positive intercept $\Delta v_2\left(0\right)$. Both effects are due to the electric fields created by the colliding ions. These fields have quadrupole asymmetry of the magnitude and the sign needed to account for the nonzero intercept $\Delta v_2\left(0\right)>0$ in the RHIC data. One of the mechanisms also involves the chiral magnetic effect. This mechanism, although negligible at RHIC energies, may become important at the CERN Large Hadron Collider energies.

The Airy structure of the nuclear rainbow and prerainbow in inelastic and elastic $\alpha +{}^{16}$O scattering is studied with the coupled channel method using a folding potential derived from the microscopic wave functions of ${}^{16}$O. The theoretical calculations reproduce the characteristic energy evolution of the Airy minimum of the experimental angular distributions. The energy levels with $\alpha$-cluster structure in ${}^{20}$Ne are reproduced well using the potentials determined from the analysis of scattering. It is shown that the emergence of the $K=0_3^{+}$ $\alpha$-cluster band with core excitation at 7.19 MeV in ${}^{20}$Ne is intimately related to the emergence of the prerainbow and rainbow in inelastic scattering to the ${}^{16}$O($0_2^{+}$). It is found that the $\alpha$-cluster states with core excitation, the prerainbow and the rainbow in inelastic scattering are understood in a unified way as well as in the case of elastic scattering.

We apply the successful Monte Carlo Glauber and IP-Glasma initial-state models of heavy-ion collisions to the much smaller size systems produced in proton-proton, proton-nucleus, and deuteron-nucleus collisions. We observe a significantly greater sensitivity of the initial-state geometry to details of multiparticle production in these models compared to nucleus-nucleus collisions. In particular, we find that the size of the system produced in $p+A$ collisions is very similar to the one produced in $p+p$ collisions and predict comparable Hanbury-Brown-Twiss radii in the absence of flow in both systems. Differences in the eccentricities computed in the models are large, while differences among the generated flow coefficients $v_2$ and $v_3$ are smaller. For a large number of participants in proton-lead collisions, the $v_2$ generated in the IP-Glasma model is comparable to the value obtained in proton-proton collisions. Viscous corrections to flow are large over characteristic lifetimes in the smaller size systems. In contrast, viscous contributions are significantly diminished over the longer space-time evolution of a heavy-ion collision.