Structures of excited states in ${}^{14}\mathrm{C}$ are investigated with a method of $\beta$-$\gamma$ constraint antisymmetrized molecular dynamics in combination with the generator coordinate method. Various excited states with the developed $3\alpha$-cluster core structures are suggested in positive- and negative-parity states. In the positive-parity states, triaxial deformed and linear-chain structures are found to construct excited bands. Interestingly, ${}^{10}\mathrm{Be}$$+\alpha$ correlation is found in the cluster states above the ${}^{10}\mathrm{Be}$$+\alpha$ threshold energy.

Recent experiments have reached the neutron-rich Cr isotope with $N=40$ and confirmed enhanced collectivity near this subshell. The current data focus on low-spin spectroscopy only, with little information on the states where high-$j$ particles align their spins with the system rotation. By applying the projected shell model, we show that rotation alignment occurs in neutron-rich even-even Cr nuclei as early as spin 8$\hslash$ and, owing to shell filling, the aligning particles differ in different isotopes. It is suggested that observation of irregularities in moments of inertia is a direct probe of the deformed single-particle scheme in this exotic mass region.

The discrete energy eigenvalues of two nucleons interacting with a finite-range nuclear force and confined to a harmonic potential are used to numerically reconstruct the free-space scattering phase shifts. The extracted phase shifts are compared to those obtained from the exact continuum scattering solution and agree within the uncertainties of the calculations. Our results suggest that it might be possible to determine the amplitudes for the scattering of complex systems, such as $\mathit{nd}$, $\mathit{nt},$ or $n\alpha$, from the energy eigenvalues confined to finite volumes using ab initio bound-state techniques.

We present the effective range expansions for the ${}^1{S}_0$ and ${}^3{S}_1$ scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with ${\chi }^2/N_{\mathrm{data}}\simeq 1$) to the 2007 world $\mathit{np}$ data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.

The structure of the $\Delta J=1$ doublet bands in ${}^{128}\mathrm{Cs}$ is investigated within the framework of the interacting vector boson-fermion model. A new, purely collective interpretation of these bands is given on the basis of the used boson-fermion dynamical symmetry of the model. The energy levels of the doublet bands as well as the absolute $B(E2)$ and $B(M1)$ transition probabilities between the states of both yrast and yrare bands are described quite well. The observed odd-even staggering of both $B(M1)$ and $B(E2)$ values is reproduced by the introduction of an appropriate interaction term of quadrupole type, which produces such a staggering effect in the transition strengths. The calculations show that the appearance of doublet bands in certain odd-odd nuclei could be a consequence of the realization of a larger dynamical symmetry based on the noncompact supersymmetry group OSp(2$\Omega /12,\mathrm{R})$.

Time-odd mean fields (nuclear magnetism) and their impact on physical observables in rotating nuclei are studied in the framework of covariant density functional theory (CDFT). It is shown that they have profound effect on the dynamic and kinematic moments of inertia. Particle number, configuration, and rotational frequency dependencies of their impact on the moments of inertia have been analyzed in a systematic way. Nuclear magnetism can also considerably modify the band crossing features such as crossing frequencies and the properties of the kinematic and dynamic moments of inertia in the band crossing region. The impact of time-odd mean fields on the moments of inertia in the regions away from band crossing only weakly depends on the relativistic mean-field parametrization, reflecting good localization of the properties of time-odd mean fields in CDFT. The moments of inertia of normal-deformed nuclei considerably deviate from the rigid-body value. On the contrary, superdeformed and hyperdeformed nuclei have the moments of inertia which are close to rigid-body value. The structure of the currents in rotating frame, their microscopic origin, and the relations to the moments of inertia have been systematically analyzed. The phenomenon of signature separation in odd-odd nuclei, induced by time-odd mean fields, has been analyzed in detail.

We perform coupled-cluster calculations for the doubly magic nuclei ${}^4\mathrm{He}$, ${}^{16}\mathrm{O}$, ${}^{40,48}\mathrm{Ca}$, for neutron-rich isotopes of oxygen and fluorine, and employ “bare” and secondary renormalized nucleon-nucleon interactions. For the nucleon-nucleon interaction from chiral effective field theory at order next-to-next-to-next-to leading order, we find that the coupled-cluster approximation including triples corrections binds nuclei within 0.4 MeV per nucleon compared to data. We employ interactions from a resolution-scale dependent similarity renormalization group transformations and assess the validity of power counting estimates in medium-mass nuclei. We find that the missing contributions from three-nucleon forces are consistent with these estimates. For the unitary correlator model potential, we find a slow convergence with respect to increasing the size of the model space. For the $G$-matrix approach, we find a weak dependence of ground-state energies on the starting energy combined with a rather slow convergence with respect to increasing model spaces. We also analyze the center-of-mass problem and present a practical and efficient solution.

Charged-particle spectra associated with direct photon (${\gamma }_{\mathrm{dir}}$) and ${\pi }^0$ are measured in $p+p$ and $\mathrm{Au}+\mathrm{Au}$ collisions at center-of-mass energy $\sqrt{s_{{}_{\mathit{NN}}}}=200$ GeV with the STAR detector at the Relativistic Heavy Ion Collider. A shower-shape analysis is used to partially discriminate between ${\gamma }_{\mathrm{dir}}$ and ${\pi }^0$. Assuming no associated charged particles in the ${\gamma }_{\mathrm{dir}}$ direction (near side) and small contribution from fragmentation photons (${\gamma }_{\mathrm{frag}}$), the associated charged-particle yields opposite to ${\gamma }_{\mathrm{dir}}$ (away side) are extracted. In central $\mathrm{Au}+\mathrm{Au}$ collisions, the charged-particle yields at midrapidity ($\left|\eta \right|<1$) and high transverse momentum ($3<p_T^{\mathrm{assoc}}<16$ GeV/$c$) associated with ${\gamma }_{\mathrm{dir}}$ and ${\pi }^0$ ($\left|\eta \right|<0.9$, $8<p_T^{\mathrm{trig}}<16$ GeV/$c$) are suppressed by a factor of 3–5 compared with $p+p$ collisions. The observed suppression of the associated charged particles is similar for ${\gamma }_{\mathrm{dir}}$ and ${\pi }^0$ and independent of the ${\gamma }_{\mathrm{dir}}$ energy within uncertainties. These measurements indicate that, in the kinematic range covered and within our current experimental uncertainties, the parton energy loss shows no sensitivity to the parton initial energy, path length, or color charge.

Measured second and fourth azimuthal anisotropy coefficients $v_{2,4}(N_{\mathrm{part}},p_T)$ are scaled with the initial eccentricity ${\varepsilon }_{2,4}(N_{\mathrm{part}})$ of the collision zone and studied as a function of the number of participants $N_{\mathrm{part}}$ and the transverse momenta $p_T$. Scaling violations are observed for $p_T\lesssim 3$ GeV/c, consistent with a $p_T^2$ dependence of viscous corrections and a linear increase of the relaxation time with $p_T$. These empirical viscous corrections to flow and the thermal distribution function at freeze-out constrain estimates of the specific viscosity and the freeze-out temperature for two different models for the initial collision geometry. The apparent viscous corrections exhibit a sharp maximum for $p_T\gtrsim 3$ GeV/c, suggesting a breakdown of the hydrodynamic ansatz and the onset of a change from flow-driven to suppression-driven anisotropy.

A model-independent method of studying the forward-backward correlations in symmetric high-energy processes is developed. The method allows a systematic study of the properties of various particle sources and allows one to uncover asymmetric structures hidden in symmetric hadron-hadron and nucleus-nucleus inelastic reactions.

The clustering of color sources provides a natural framework for soft partonic interactions producing strong color fields. We study the consequences of these color fields in the production of heavy flavor and the behavior of the nuclear modification factor.

In ultrarelativistic heavy-ion collisions, the Fourier decomposition of the relative azimuthal angle, $\Delta \varphi$, distribution of particle pairs yields a large $\cos (3\Delta \varphi )$ component, extending to large rapidity separations $\Delta \eta >1$. This component captures a significant portion of the ridge and shoulder structures in the $\Delta \varphi$ distribution, which have been observed after contributions from elliptic flow are subtracted. An average finite triangularity owing to event-by-event fluctuations in the initial matter distribution, followed by collective flow, naturally produces a $\cos (3\Delta \varphi )$ correlation. Using ideal and viscous hydrodynamics and transport theory, we study the physics of triangular ($v_3$) flow in comparison to elliptic ($v_2$), quadrangular ($v_4$), and pentagonal ($v_5$) flow. We make quantitative predictions for $v_3$ at RHIC and LHC as a function of centrality and transverse momentum. Our results for the centrality dependence of $v_3$ show a quantitative agreement with data extracted from previous correlation measurements by the STAR collaboration. This study supports previous results on the importance of triangular flow in the understanding of ridge and shoulder structures. Triangular flow is found to be a sensitive probe of initial geometry fluctuations and viscosity.

Data on the photoproduction of $\omega$ mesons on nuclei have been reanalyzed in a search for in-medium modifications. The data were taken with the crystal barrel (CB)/two-arm photon spectrometer (TAPS) detector system at the ELectron Stretcher Anlage (ELSA) accelerator facility in Bonn. First results from the analysis of the data set were published by Trnka et al. [Phys. Rev. Lett. 94, 192303 (2005)], claiming a lowering of the $\omega$ mass in the nuclear medium by 14$\%$ at normal nuclear matter density. The extracted $\omega$ line shape was found to be sensitive to the background subtraction. For this reason a reanalysis of the same data set has been initiated, and a new method has been developed to reduce the background and to determine the shape and absolute magnitude of the background directly from the data. Details of the reanalysis and of the background determination are described. The $\omega$ signal on the Nb target, extracted in the reanalysis, does not show a deviation from the corresponding line shape on a ${\mathrm{LH}}_2$ target, measured as reference. The earlier claim of an in-medium mass shift is thus not confirmed. The sensitivity of the $\omega$ line shape to different in-medium modification scenarios is discussed.

In many-body theory, it is often useful to renormalize short-distance, high-momentum components of an interaction via unitary transformations. Such transformations preserve the on-shell physical observables of the two-body system (mostly phase shifts, hence unitarily connected effective interactions are often called phase equivalent) while modifying off-shell $T$-matrix elements influential in many-body systems. In this paper, I lay out a general and systematic approach for controlling the off-shell behavior of an effective interaction, which can be adjusted to many-body properties, and present an application to trapped fermions at the unitary limit.

A coupling scheme for even-even nuclei with the X(5) critical point symmetry coupled to a single valence nucleon in a $j$ orbit is proposed to approximately describe the critical point phenomena of spherical to axially deformed shape (phase) transition in odd-$A$ nuclear systems. The corresponding scheme, which can be solved analytically, is called the X$(5/(2j+1))$ model. A special case with $j=1/2$ is analyzed in detail to show its level structure and transition patterns. It is further shown that ${}^{189}\mathrm{Au}$ and ${}^{155}\mathrm{Tb}$ may be possible X$(5/(2j+1))$ symmetry candidates with $j=1/2$ and $j=3/2$, respectively.

The high-spin hyperdeformed nuclear states treated as dinuclear or quasimolecular configurations are suggested to be directly populated in heavy ion collisions at sub-barrier energies. Tunneling through the Coulomb barrier is considered using the quantum diffusion approach based on the formalism of reduced density matrix. The reactions ${}^{48}\mathrm{Ca}+{}^{86}\mathrm{Kr}$,${}^{124}\mathrm{Sn}$,${}^{136}\mathrm{Xe}$,${}^{138}\mathrm{Ba}$,${}^{140}\mathrm{Ce}$, ${}^{58}\mathrm{Ni}+{}^{58}\mathrm{Ni}$, and ${}^{40,48}\mathrm{Ca}+{}^{40,48}\mathrm{Ca}$, are suggested for populating high-spin hyperdeformed states. The partial production and identification cross sections for the hyperdeformed states are calculated as the functions of bombarding energy.

The radiative proton-capture reactions ${}^{19}\mathrm{Ne}$($p,\gamma$)${}^{20}\mathrm{Na}$, ${}^{23}\mathrm{Mg}$($p,\gamma$)${}^{24}\mathrm{Al}$, ${}^{27}\mathrm{Si}$($p,\gamma$)${}^{28}\mathrm{P}$, ${}^{31}\mathrm{S}$($p,\gamma$)${}^{32}\mathrm{Cl}$, and ${}^{35}\mathrm{Ar}$($p,\gamma$)${}^{36}\mathrm{K}$ potentially influence energy generation and/or nucleosynthesis during explosive hydrogen burning in classical novae and/or type I x-ray bursts. The thermonuclear rates of these reactions are dependent on resonance energies $E_r=E_x-Q$ and strengths $\omega \gamma$. The ${}^{20}\mathrm{Ne}$(${}^3\mathrm{He}$,$t$)${}^{20}\mathrm{Na}$, ${}^{24}\mathrm{Mg}$(${}^3\mathrm{He}$,$t$)${}^{24}\mathrm{Al}$, ${}^{28}\mathrm{Si}$(${}^3\mathrm{He}$,$t$)${}^{28}\mathrm{P}$, ${}^{32}\mathrm{S}$(${}^3\mathrm{He}$,$t$)${}^{32}\mathrm{Cl}$, and ${}^{36}\mathrm{Ar}$(${}^3\mathrm{He}$,$t$)${}^{36}\mathrm{K}$ reactions have been measured using a 32-MeV, ${}^3\mathrm{He}$${}^{2+}$ beam; ion-implanted carbon-foil targets developed at the University of Washington; and the Munich Q3D magnetic spectrograph. This experiment has already yielded precision mass measurements of ${}^{20}\mathrm{Na}$, ${}^{24}\mathrm{Al}$, ${}^{28}\mathrm{P}$, and ${}^{32}\mathrm{Cl}$ [C. Wrede et al., Phys. Rev. C 81, 055503 (2010)], which are used presently to constrain the corresponding ($p,\gamma$) reaction $Q$ values. The new ${}^{24}\mathrm{Al}$ and ${}^{28}\mathrm{P}$ masses resolve a discrepancy in the energy of the lowest-energy resonance in the ${}^{23}\mathrm{Mg}$($p,\gamma$)${}^{24}\mathrm{Al}$ reaction and better constrain a direct measurement of its strength. Excitation energies in ${}^{32}\mathrm{Cl}$ and ${}^{36}\mathrm{K}$ have also been measured. An important new proton-unbound level has been found at $E_x=2196.9(7)$ keV in ${}^{36}\mathrm{K}$ and the uncertainties in ${}^{36}\mathrm{K}$ excitation energies have been reduced by over an order of magnitude. Using the new data on ${}^{36}\mathrm{K}$, the $A=36$, $T=1$ triplets have been reassigned. The thermonuclear ${}^{35}\mathrm{Ar}$($p,\gamma$)${}^{36}\mathrm{K}$ reaction rate is found to be much higher than a commonly adopted rate and this could affect energy generation in type I x-ray bursts.

The neutron-capture cross sections of ${}^{168}\mathrm{Yb}$, ${}^{180}\mathrm{W}$, ${}^{184}\mathrm{Os}$, ${}^{190}\mathrm{Pt}$, and ${}^{196}\mathrm{Hg}$ have been measured by means of the activation technique. The samples were irradiated in a quasistellar neutron spectrum of $\mathit{kT}=25$ keV, which was produced at the Karlsruhe 3.7-MV Van de Graaff accelerator via the ${}^7\mathrm{Li}$($p,n$)${}^7\mathrm{Be}$ reaction. Systematic uncertainties were investigated in repeated activations with different samples and by variation of the experimental parameters, that is, irradiation times, neutron fluxes, and $\gamma$-ray counting conditions. The measured data were converted into Maxwellian-averaged cross sections at $\mathit{kT}=30$ keV, yielding $1214\pm 61$, $624\pm 54$, $590\pm 43$, $511\pm 46$, and $201\pm 11$ mb for ${}^{168}\mathrm{Yb}$, ${}^{180}\mathrm{W}$, ${}^{184}\mathrm{Os}$, ${}^{190}\mathrm{Pt}$, and ${}^{196}\mathrm{Hg}$, respectively. The present results either represent first experimental data (${}^{168}\mathrm{Yb}$, ${}^{184}\mathrm{Os}$, and ${}^{196}\mathrm{Hg}$) or could be determined with significantly reduced uncertainties (${}^{180}\mathrm{W}$ and ${}^{190}\mathrm{Pt}$). These measurements are part of a systematic study of stellar ($n,\gamma$) cross sections of the stable $p$ isotopes.

We review predictions for the energy of the excited $0^{+}$ state of ${}^{12}\mathrm{O}$ and present new calculations of its width. Results are compared with those of a recent experiment.