The $2_1^{+}$ and $2_2^{+}$ states of the neutron-rich isotope ${}^{80}\mathrm{Ge}$ were studied by intermediate-energy heavy-ion scattering, providing for the first time the experimental value of $B(E2;2_2^{+}\to 0_{\mathrm{g}.\mathrm{s}.}^{+})$ for ${}^{80}\mathrm{Ge}$. The experimental data are well reproduced by large-scale shell model calculations, which suggest the important role of the proton particle-hole $2p_{3/2}\text{−}1f_{5/2}$ excitation in the configuration of the $2_2^{+}$ state.

A candidate for chiral bands was found in ${}^{198}\mathrm{Tl}$ for the first time in a mass region of oblate (or nonaxial with $\gamma ⩾{30}^{°}$) deformed nuclei. Two bands show very similar quasiparticle alignments, moments of inertia, and $B(M1)/B(E2)$ ratios. They have a relative excitation energy of about 500 keV and different patterns of energy staggering. Calculations using the two-quasiparticle-plus-triaxial-rotor model with residual proton-neutron interaction included show that a triaxial deformation with $\gamma ~{44}^{°}$ agrees very well with all the experimental observations. Furthermore, considerable energy staggering for both partner bands was calculated for this $\pi h_{9/2}\otimes \nu i_{13/2}^{-1}$ configuration at $\gamma ~{30}^{°}$, suggesting that chiral bands may have substantial energy staggering.

The Faddeev equation for three-nucleon scattering, based on an exactly Poincaré invariant formulation of quantum mechanics, is solved for projectile energies up to 2 GeV. As in the nonrelativistic three-body problem, the three-body dynamics is determined, up to three-body interactions, by the two-body dynamics and cluster properties. The two-body interactions are determined, up to a unitary scattering equivalence, by two-body scattering data, which in our application are generated by a nonrelativistic Malfliet-Tjon interaction. The Faddeev equation is directly solved in a kinematic momentum representation without employing a partial-wave decomposition. The solution of the Faddeev equation is generated using Padé summation, and the numerical feasibility and stability of the solution is demonstrated. Scattering observables for elastic and breakup scattering are calculated for projectile energies in the intermediate energy range up to 2 GeV, and compared with their nonrelativistic counterparts. The convergence of the multiple scattering series is investigated as a function of the projectile energy in different scattering observables and configurations. The complementary roles of kinematic and dynamical contributions to our Poincaré invariant model are investigated. Approximations to the two-body interaction embedded in the three-particle space are compared with the exact treatment.

Previous inelastic scattering experiments populating the $2_1^{+}$ state in ${}^{16}\mathrm{C}$ using ${}^{208}\mathrm{Pb}$ and liquid hydrogen targets have been reanalyzed. Exploiting the different sensitivities of the two probes for the neutron and proton distributions, the neutron and proton deformation lengths and transition strengths have been derived by means of distorted wave calculations. The determined $B(E2)$ value is consistent with the results of lifetime measurements while the large difference in the neutron and proton transition strengths shows relatively enhanced neutron excitations.

We argue that hadron production in coherent diffraction of protons on a heavy nucleus provides a very sensitive probe of the low-$x$ QCD dynamics. This process probes the BFKL dynamics in protons and the nonlinear gluon evolution in nuclei. We calculate the diffractive hadron production cross sections in the BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC) kinematic regions. To study the nuclear effects we introduce the diffractive nuclear modification factor. We show that, unlike the nuclear modification factor for inclusive hadron production that has very interesting dynamics at RHIC but is expected to be almost completely saturated at the LHC, the nuclear modification factor for diffractive production exhibits a nontrivial behavior at both RHIC and LHC.

Using a simple model for nuclear generalized parton distributions (GPDs), we study the role of the neutron contribution to nuclear deeply virtual Compton scattering (DVCS) observables. As an example, we use the beam-spin asymmetry $A_{\mathrm{LU}}^A$ measured in coherent and incoherent DVCS on a wide range of nuclear targets in the HERMES and JLab kinematics. We find that at small values of the momentum transfer $t,A_{\mathrm{LU}}^A$ is dominated by the coherent-enriched contribution, which enhances $A_{\mathrm{LU}}^A$ compared to the free proton asymmetry $A_{\mathrm{LU}}^p,A_{\mathrm{LU}}^A(\varphi )/A_{\mathrm{LU}}^p(\varphi )=1.8-2.2$. At large values of $t$, the nuclear asymmetry is dominated by the incoherent contribution and $A_{\mathrm{LU}}^A/(\varphi )A_{\mathrm{LU}}^p(\varphi )=0.66-0.74$. The deviation of $A_{\mathrm{LU}}^A(\varphi )/A_{\mathrm{LU}}^p(\varphi )$ from unity at large $t$ is a result of the neutron contribution, which gives a possibility to constrain neutron GPDs in incoherent nuclear DVCS. A similar trend is expected for other DVCS asymmetries.

A high-precision branching ratio measurement for the superallowed ${\beta }^{+}$ decay of ${}^{62}\mathrm{Ga}$ was performed at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility. The 8π spectrometer, an array of 20 high-purity germanium detectors, was employed to detect the γ rays emitted following Gamow-Teller and nonanalog Fermi ${\beta }^{+}$ decays of ${}^{62}\mathrm{Ga}$, and the SCEPTAR plastic scintillator array was used to detect the emitted β particles. Thirty γ rays were identified following ${}^{62}\mathrm{Ga}$ decay, establishing the superallowed branching ratio to be $99.858(8)\%$. Combined with the world-average half-life and a recent high-precision $Q$-value measurement for ${}^{62}\mathrm{Ga}$, this branching ratio yields an $\mathit{ft}$ value of $3074.3\pm 1.1$ s, making ${}^{62}\mathrm{Ga}$ among the most precisely determined superallowed $\mathit{ft}$ values. Comparison between the superallowed $\mathit{ft}$ value determined in this work and the world-average corrected $\overline{\mathcal{F}t}$ value allows the large nuclear-structure-dependent correction for ${}^{62}\mathrm{Ga}$ decay to be experimentally determined from the CVC hypothesis to better than 7$\%$ of its own value, the most precise experimental determination for any superallowed emitter. These results provide a benchmark for the refinement of the theoretical description of isospin-symmetry breaking in $A⩾62$ superallowed decays.

The ${}^{92}\mathrm{Mo}$($\alpha ,n$)${}^{95}\mathrm{Ru}$, ${}^{94}\mathrm{Mo}$($\alpha ,n$)${}^{97}\mathrm{Ru}$, and ${}^{112}\mathrm{Sn}$($\alpha ,\gamma$)${}^{116}\mathrm{Te}$ cross sections were measured at the upper end of the $p$-process Gamow window between 8.2 and 11.1 MeV. Our results are slightly lower than global Hauser-Feshbach calculations from the code NON-SMOKER, but still within the uncertainty of the prediction. The ${}^{112}\mathrm{Sn}$($\alpha ,\gamma$)${}^{116}\mathrm{Te}$ cross section agrees well with a recently measured thick-target cross section in the same energy range. For the ${}^{92,94}\mathrm{Mo}$($\alpha ,n$) reactions the present data close to the reaction thresholds could eliminate previous uncertainties within a factor of 20, and we can present now useful comparisons to statistical model calculations with different optical potentials.

We address the problem of extrapolating experimental thermonuclear reaction rates toward high stellar temperatures ($T>1$ GK) by using statistical model (Hauser-Feshbach) results. Reliable reaction rates at such temperatures are required for studies of advanced stellar burning stages, supernovae, and x-ray bursts. Generally accepted methods are based on the concept of a Gamow peak. We follow recent ideas that emphasized the fundamental shortcomings of the Gamow peak concept for narrow resonances at high stellar temperatures. Our new method defines the effective thermonuclear energy range (ETER) by using the 8th, 50th, and 92nd percentiles of the cumulative distribution of fractional resonant reaction rate contributions. This definition is unambiguous and has a straightforward probability interpretation. The ETER is used to define a temperature at which Hauser-Feshbach rates can be matched to experimental rates. This matching temperature is usually much higher compared to previous estimates that employed the Gamow peak concept. We suggest that an increased matching temperature provides more reliable extrapolated reaction rates since Hauser-Feshbach results are more trustwhorthy the higher the temperature. Our ideas are applied to 21 ($p,\gamma$), ($p,\alpha$), and ($\alpha ,\gamma$) reactions on $A=20-40$ target nuclei. For many of the cases studied here, our extrapolated reaction rates at high temperatures differ significantly from those obtained using the Gamow peak concept.

We solve the relativistic Navier-Stokes equations with homogeneous boost-invariant boundary conditions, and perform a stability analysis of the solution. We show that, if the bulk viscosity has a peak around $T_c$, as inferred from QCD-based arguments, the background solution “freezes” at $T_c$ to a nearly constant temperature state. This state is however highly unstable with respect to certain inhomogeneous modes. Calculations show that these modes have enough time to blow up and tear the system into droplets. We conjecture that this is how freeze-out occurs in the QGP created in heavy ion collisions, and perhaps similar transitions in the early universe.

Electroproduction of exclusive ϕ vector mesons has been studied with the CLAS detector in the kinematic range $1.4⩽Q^2⩽3.8$ GeV${}^2,0.0⩽t^{\text{'}}⩽3.6$ GeV${}^2$, and $2.0⩽W⩽3.0$ GeV. The scaling exponent for the total cross section as $1/(Q^2+M_{\varphi }^2){}^n$ was determined to be $n=2.49\pm 0.33$. The slope of the four-momentum transfer $t^{\text{'}}$ distribution is $b_{\varphi }=0.98\pm 0.17$ GeV${}^{-2}$. Under the assumption of $s$-channel helicity conservation, we determine the ratio of longitudinal to transverse cross sections to be $R=0.86\pm 0.24$. A two-gluon exchange model is able to reproduce the main features of the data.

We present a method based on mean-field states generated by triaxial quadrupole constraints that are projected on particle number and angular momentum and mixed by the generator coordinate method on the quadrupole moment. This method is equivalent to a seven-dimensional GCM calculation, mixing all five degrees of freedom of the quadrupole operator and the gauge angles for protons and neutrons. A first application to ${}^{24}\mathrm{Mg}$ permits a detailed analysis of the effects of triaxial deformations and of $K$ mixing.

Volume fluctuations are introduced in a statistical modeling of relativistic particle collisions. The microcanonical ensemble is used, and the volume fluctuations are assumed to have specific scaling properties. This leads to the KNO scaling of the particle multiplicity distributions as measured in $p+p$ interactions. A striking prediction of the model is a power law form of the single particle momentum spectrum at high momenta. Moreover, the mean multiplicity of heavy particles also decreases as a function of the particle mass according to a power law. Finally, it is shown that the dependence of the momentum spectrum on the particle mass and momentum reduces to the dependence on the particle energy. These results resemble the properties of particle production in collisions of high energy particles.

The ${\beta }^{+}$/EC half-lives of medium heavy $N~Z$ nuclei with mass number $A~64\text{−}80$ are calculated within the deformed shell model (DSM) based on Hartree-Fock states by employing a modified Kuo interaction in (${}^2{p}_{3/2},{}^1{f}_{5/2},{}^2{p}_{1/2},{}^1{g}_{9/2}$) space. The DSM model has been quite successful in predicting many spectroscopic properties of $N~Z$ medium heavy nuclei with $A~64\text{−}80$. The calculated ${\beta }^{+}$/EC half-lives, for prolate and oblate shapes, compare well with the predictions of the calculations with Skyrme force by Sarriguren et al. Going further, following recent searches, half-lives for $2\nu$ ${\beta }^{+}{\beta }^{+}/{\beta }^{+}$EC/ECEC decay for the nucleus ${}^{78}\mathrm{Kr}$ are calculated using DSM and the results compare well with QRPA predictions.

Large basis untruncated shell model (SM) calculations have been done for the $A=138$ neutron-rich nuclei in the $\pi (\mathit{gdsh})\oplus \nu (\mathit{hfpi})$ valence space above the ${}^{132}\mathrm{Sn}$ core using two (1+2) -body nuclear Hamiltonians, viz., realistic CWG and empirical SMPN. Calculated binding energies, excitation spectra, and wave function structures are compared for even-even $A=138$ isobars for which experimental data are available. The nearly vibrational states in ${}^{138}\mathrm{Te}$, Xe, and the $B(E2;2^{+}\to 0^{+})$ value in ${}^{138}\mathrm{Xe}$ are excellently reproduced by both the interactions. For ${}^{138}\mathrm{Ba}$, the calculated spectra and the $B(E2;2^{+}\to 0^{+})$ value also agree very well with the experimental results. But the two theoretical results differ dramatically for ${}^{138}\mathrm{Sn}$, a nucleus on the $r$-process path. CWG predicts nearly constant energies of $2_1^{+}$ states for the even-even Sn isotopes above the ${}^{132}\mathrm{Sn}$ core, normally expected for semi-magic nuclei. But SMPN predicts a remarkable new feature: decreasing $E(2_1^{+})$ energies with increasing neutron number. The predicted energies for the Sn isotopes fit in the systematics for the $E(2_1^{+})$ energies of their isotones with $Z>50$. Despite their differences, both interactions predict the $6_1^{+}$ state to be a $\approx 0.3\hspace{0.5em}\mu \mathrm{s}$ isomer in ${}^{138}\mathrm{Sn}$. Calculated magnetic dipole moments and electric quadrupole moments of the states in these isobars are compared with the experimental data wherever available. The appearance of deformation and evolution of collectivity in nuclei in this valence space are discussed.

The near zone energy-momentum tensor of a supersonic heavy quark jet moving through a strongly coupled $\mathcal{N}=4$ super Yang-Mills (SYM) plasma is analyzed in terms of first-order Navier-Stokes hydrodynamics. It is shown that the hydrodynamic description of the near quark region worsens with increasing quark velocities. For realistic quark velocities, $v=0.99$, the nonhydrodynamic region is located at a narrow band surrounding the quark with a width of approximately $3/\pi T$ in the direction parallel to the quark's motion and with a length of roughly $10/\pi T$ in the perpendicular direction. Our results can be interpreted as an indication of the presence of coherent Yang-Mills fields where deviation from hydrodynamics is at its maximum. In the region where hydrodynamics does provide a good description of the system's dynamics, the flow velocity is so small that all the nonlinear terms can be dropped. Our results, which are compatible with the thermalization timescales extracted from elliptic flow measurements, suggest that if anti-de-Sitter/conformal field theory (AdS/CFT) provides a good description of the BNL Relativistic Heavy Ion Collider system, the bulk of the quenched jet energy has more than enough time to locally thermalize and become encoded in the collective flow. The resulting flow pattern close to the quark, however, is shown to be considerably different from the superposition of Mach cones and diffusion wakes observed at large distances.

The determination of nonspherical angular momentum amplitudes in nucleons at long ranges (low $Q^2$) was accomplished through the $p(\overrightarrow{e},e^{\text{'}}p){\pi }^0$ reaction in the Δ region at $Q^2=0.060$, 0.127, and 0.200 (GeV/$c){}^2$ at the Mainz Microtron with an accuracy for the cross sections of 4%. The results for the dominant transition magnetic dipole amplitude and the quadrupole to dipole ratios have been obtained with an estimated model uncertainty that is approximately the same as the experimental uncertainty. Lattice and effective field theory predictions agree with our data within the relatively large estimated theoretical uncertainties. Phenomenological models are in good agreement with experiment when the resonant amplitudes are adjusted to the data. To check reaction model calculations additional data were taken for center-of-mass energies below resonance and for the ${\sigma }_{{\mathit{LT}}^{\text{'}}}$ structure function. These results confirm the dominance, and general $Q^2$ variation, of the pionic contribution at large distances.

The proposed $\nu p$ process, which occurs in the early time proton-rich neutrino winds of core-collapse supernovae, has the potential to resolve the long-standing uncertainty in the production of the light $p$-nuclei ${}^{92}\mathrm{Mo}$ and ${}^{94}\mathrm{Mo}$. A recent study incorporating this $\nu p$ process has indicated that the proton separation energy $S_p$ of ${}^{93}\mathrm{Rh}$ is especially important in determining the relative production of these two isotopes. To reproduce the observed solar ${}^{92}\mathrm{Mo}$/${}^{94}\mathrm{Mo}$ abundance ratio of 1.57 a $S_p$ value for ${}^{93}\mathrm{Rh}$ of $1.64\pm 0.1$ MeV is required. The previously unknown masses of ${}^{92}\mathrm{Ru}$ and ${}^{93}\mathrm{Rh}$ have been measured with the Canadian Penning Trap mass spectrometer resulting in an experimental value for $S_p$(${}^{93}\mathrm{Rh}$) of $2.007\pm 0.009$ MeV. This implies that with our current understanding of the conditions in core-collapse supernova explosions the $\nu p$ process is not solely responsible for the observed solar ${}^{92}\mathrm{Mo}$/${}^{94}\mathrm{Mo}$ abundance ratio.

We consider two-component fermions on the lattice in the unitarity limit. This is an idealized limit of attractive fermions where the range of the interaction is zero and the scattering length is infinite. Using Euclidean time projection, we compute the ground state energy using four computationally different but physically identical auxiliary-field methods. The best performance is obtained using a bounded continuous auxiliary field and a nonlocal updating algorithm called the hybrid Monte Carlo. With this method, we calculate results for 10 and 14 fermions at lattice volumes $4^3,5^3,6^3,7^3,8^3$ and extrapolate to the continuum limit. For 10 fermions in a periodic cube, the ground state energy is $0.292(12)$ times the ground state energy for noninteracting fermions. For 14 fermions, the ratio is $0.329(5)$.

Coulomb excitation of the proton-rich nucleus ${}^{20}\mathrm{Mg}$ was studied using a radioactive ${}^{20}\mathrm{Mg}$ beam at $58A$ MeV impinging on a lead target. The reduced transition probability $B(E2;0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+})$ was extracted to be $177(32)\hspace{0.5em}{e}^2$ fm${}^4$, which agrees with the theoretical predictions by a cluster model assuming ${}^{16}\mathrm{O}\hspace{0.5em}+\hspace{0.5em}2p\hspace{0.5em}+\hspace{0.5em}2p$ structure, a mean-field approach based on the angular momentum projected generator coordinate method, and the USD shell model. The ratio of the neutron-to-proton multipole matrix elements $M_{\mathrm{n}}/M_{\mathrm{p}}$ in the mirror nucleus ${}^{20}\mathrm{O}$ was deduced to be 2.51(25) with the $M_{\mathrm{n}}$ value evaluated from the measured $B(E2)$ value for ${}^{20}\mathrm{Mg}$ with the help of isospin symmetry. The results confirm the large $M_{\mathrm{n}}/M_{\mathrm{p}}$ value previously reported in ${}^{20}\mathrm{O}$, leading to the dominant role of the four valence nucleons in the $2_1^{+}$ excitation and persistence of the ${}^{16}\mathrm{O}$ core in ${}^{20}\mathrm{O}$ and ${}^{20}\mathrm{Mg}$.