Narrow resonances in systems with short-range interactions are discussed in an effective field theory (EFT) framework. An effective Lagrangian is formulated in the form of a combined expansion in powers of a momentum $Q\ll \Lambda$—a short-distance scale—and an energy difference $\delta \epsilon =|E-{\epsilon }_0|\ll {\epsilon }_0$—a resonance peak energy. At leading order in the combined expansion, a two-body scattering amplitude is the sum of a smooth background term of order $Q^0$ and a Breit-Wigner term of order $Q^2(\delta \epsilon ){}^{-1}$ which becomes dominant for $\delta \epsilon \lesssim Q^3$. Such an EFT is applicable to systems in which short-distance dynamics generates a low-lying quasistationary state. The EFT is generalized to describe a narrow low-lying resonance in a system of charged particles. It is shown that in the case of Coulomb repulsion, a two-body scattering amplitude at leading order in a combined expansion is the sum of a Coulomb-modified background term and a Breit-Wigner amplitude with parameters renormalized by Coulomb interactions.

The predictive power of the coherent state (CS) approach to the interacting boson model (IBM) is tested far from the IBM dynamical symmetry limits. The transitional region along the $\gamma$-unstable path from U(5) to O(6) is considered. Excitation energy of the excited $\beta$ band and intraband and interband transitions obtained within the CS approach are compared with the exact results as a function of the boson number $N$. We find that the CS formalism provides approximations to the exact results that are correct up to the order $1/N$ in the transitional region, except in a narrow region close to the critical point.

A Gammasphere experiment has been carried out using the ${}^{122}\mathrm{Sn}({}^{36}\mathrm{S},4n)$ reaction to search for excited superdeformed (SD) structures in ${}^{154}\mathrm{Dy}$ to investigate the properties of neutron orbitals at superdeformation. Five new excited SD bands have been identified with intensities ranging from $~0.7\%$ to $~0.03\%$ relative to the ${}^{154}\mathrm{Dy}$ reaction channel. Bands SD1, SD3, SD5, and SD6 are interpreted within the cranked relativistic mean field theory by using the effective alignment method. High-$N$ intruder configurations are also discussed for bands SD2 and SD4, based on a comparison of their dynamic moments of inertia, which rise with increasing rotational frequency, with those of similar bands in neighboring nuclei.

We consider the semiclassical rigid-body quantization of Skyrmion solutions of mass numbers $B=4,6,8,10$, and 12. We determine the allowed quantum states for each Skyrmion and find that they often match the observed states of nuclei. The spin and isospin inertia tensors of these Skyrmions are accurately calculated for the first time and are used to determine the excitation energies of the quantum states. We calculate the energy level splittings, using a suitably chosen parameter set for each mass number. We find good qualitative and encouraging quantitative agreement with experiment. In particular, the rotational bands of beryllium-8 and carbon-12, along with isospin 1 triplets and isospin 2 quintets, are especially well reproduced. We also predict the existence of states that have not yet been observed and make predictions for the unknown quantum numbers of some observed states.

Two isomeric states have been identified in ${}^{255}\mathrm{Lr}$. The decay of the isomers populates rotational structures. Comparison with macroscopic-microscopic calculations suggests that the lowest observed sequence is built upon the $[624]9/2^{+}$ Nilsson state. However, microscopic cranked relativistic Hartree-Bogoliubov (CRHB) calculations do not reproduce the moment of inertia within typical accuracy. This is a clear challenge to theories describing the heaviest elements.

The effective chiral Lagrangian for cold dense nuclear matter is constructed, in which the chemical potential corresponding to the baryon number density of QCD is introduced and included in the effective Lagrangian as an external field. A nonperturbative approach inspired by chiral perturbation theory is employed to calculate the baryon number density and its susceptibility, pressure, and quark condensate. The relevant discussions of the obtained results are given.

We report measurements of the beam spin asymmetry in deeply virtual Compton scattering (DVCS) at an electron beam energy of $4.8$ GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, $1.0<Q^2<2.8$ (GeV/$c$)${}^2$, $0.12<x_B<0.48$, and $0.1<-t<0.8$ (GeV/$c$)${}^2$, using the reaction $\overrightarrow{e}p\to e^{\text{'}}\mathit{pX}$. The number of $\mathrm{H}(e,e^{\text{'}}\gamma p)$ and $\mathrm{H}(e,e^{\text{'}}{\pi }^{0}p)$ events are separated in each $(Q^2,x_B,t)$ bin by a fit to the line shape of the $\mathrm{H}(e,e^{\text{'}}p)X$ $M_x^2$ distribution. The validity of the method was studied in detail using experimental and simulated data. It was shown that with the achieved missing mass squared resolution and the available statistics, the separation of DVCS–Bethe-Heitler and ${\pi }^0$ events can reliably be done with less than 5% uncertainty. Also, the $Q^2$ and $t$ dependences of the $\sin \varphi$ moments of the asymmetry are extracted and compared with theoretical calculations.

Strong evidence of the nucleosynthesis of Galactic ${}^{26}\mathrm{Al}$ has been found through measurements involving excesses in ${}^{26}\mathrm{Mg}$ from the decay of ${}^{26}\mathrm{Al}$ in meteoritic inclusions and the 1.809-MeV $\gamma$-ray line detected by satellites such as CGRO and INTEGRAL. Several sites for the production of ${}^{26}\mathrm{Al}$ have been suggested, including ONe novae. Destruction of ${}^{26}\mathrm{Al}$ in ONe novae is possible via the reactions ${}^{26}\mathrm{Al}{}^g(p,\gamma ){}^{27}\mathrm{Si}$ and ${}^{26}\mathrm{Al}{}^m(p,\gamma ){}^{27}\mathrm{Si}$. In the present work, resonance parameters for the ${}^{26}\mathrm{Al}{}^m(p,\gamma ){}^{27}\mathrm{Si}$ reaction have been determined via studies of the ${}^{27}\mathrm{Al}({}^3\mathrm{He},t){}^{27}\mathrm{Si}{}^{*}(p){}^{26}\mathrm{Al}{}^m$ and ${}^{28}\mathrm{Si}({}^3\mathrm{He},\alpha ){}^{27}\mathrm{Si}{}^{*}(p){}^{26}\mathrm{Al}{}^m$ reactions. Several new ${}^{26}\mathrm{Al}{}^m+p$ resonances have been discovered within 1 MeV above the proton threshold of 7.691 MeV. Excitation energies and proton-branching ratios for those and previously known states are reported.

A two-nucleon potential and consistent electromagnetic currents are derived in chiral effective field theory $(\chi \mathrm{EFT})$ at, respectively, $Q^2$ (or ${\mathrm{N}}^2\mathrm{LO}$) and $eQ$ (or ${\mathrm{N}}^3\mathrm{LO}$), where $Q$ generically denotes the low-momentum scale and $e$ is the electric charge. Dimensional regularization is used to renormalize the pion-loop corrections. A simple expression is derived for the magnetic dipole $(M1)$ operator associated with pion loops, consisting of two terms, one of which is determined, uniquely, by the isospin-dependent part of the two-pion-exchange potential. This decomposition is also carried out for the $M1$ operator arising from contact currents, in which the unique term is determined by the contact potential. Finally, the low-energy constants entering the ${\mathrm{N}}^2\mathrm{LO}$ potential are fixed by fits to the $\mathit{np}$ $S$- and $P$-wave phase shifts up to 100 MeV laboratory energies.

We discuss the use of reduced fusion cross sections in the derivation of fusion barrier distributions. We show that the elimination of static effects associated with system sizes and optical potentials obtained by the recently introduced fusion functions can be extended to barrier distributions. This can be a useful tool for systematic studies of breakup coupling effects in fusion processes.

A systematic study of the ${\pi }^{-}/{\pi }^{+}$ ratio in heavy-ion collisions with the same neutron/proton ratio but different masses can help single out effects of the nuclear mean field on pion production. Based on simulations using the IBUU04 transport model, it is found that the ${\pi }^{-}/{\pi }^{+}$ ratio in head-on collisions of ${}^{48}\mathrm{Ca}+{}^{48}\mathrm{Ca}$, ${}^{124}\mathrm{Sn}+{}^{124}\mathrm{Sn}$, and ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ at beam energies from 0.25 to 0.6 GeV/nucleon increases with increasing the system size or decreasing the beam energies. A comprehensive analysis of the dynamical isospin fractionation and the ${\pi }^{-}/{\pi }^{+}$ ratio as well as their time evolution and spatial distributions demonstrates clearly that the ${\pi }^{-}/{\pi }^{+}$ ratio is an effective probe of the high-density behavior of the nuclear symmetry energy.

We analyze PHENIX near-side ridge data for central $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV with the momentum-kick model, in which a near-side jet emerges near the surface, kicks medium partons, loses energy, and fragments into the trigger particle and fragmentation products. The kicked medium partons subsequently materialize as the observed ridge particles, which carry direct information on the early parton momentum distribution and the magnitude of the momentum kick. We find that the PHENIX ridge data can be described well by the momentum-kick model and the extracted early partons momentum distribution has a thermal-like transverse distribution and a rapidity plateau structure. We also find that the parton-parton scattering between the jet parton and the medium parton involves the exchange of a nonperturbative pomeron, for jet partons in momentum range considered in the near-side ridge measurements.

We report on the first measurement of the absolute transition strength $B(E2;0_1^{+}\to 2_1^{+})$ in the self-conjugate nucleus ${}^{68}\mathrm{Se}$. It is found that the $0_1^{+}\to 2_1^{+}$ transition displays a strength similar to that for the triaxial ${}^{64}\mathrm{Ge}$ nucleus, in sharp contrast to the much stronger collectivity observed for the oblate ${}^{72}\mathrm{Kr}$ nucleus. Shape evolution along the $N=Z$ line from zinc to strontium is analyzed through beyond-mean-field calculations using the D1S force. Over this narrow mass region the nuclear structure shows clear-cut transition from prolate to oblate and back to prolate, with ${}^{68}\mathrm{Se}$ standing as pivotal between triaxial and oblate deformations.

Relativistic mean-field calculations of multi-$\overline{K}$ hypernuclei are performed by adding $K^{-}$ mesons to particle-stable configurations of nucleons, $\Lambda$ and $\Xi$ hyperons. For a given hypernuclear core, the calculated $\overline{K}$ separation energy $B_{\overline{K}}$ saturates with the number of $\overline{K}$ mesons for more than roughly 10 mesons, with $B_{\overline{K}}$ bounded from above by 200 MeV. The associated baryonic densities saturate at values 2–3 times nuclear-matter density within a small region where the $\overline{K}$-meson densities peak, similarly to what was found for multi-$\overline{K}$ nuclei. The calculations demonstrate that particle-stable multistrange $\{N,\Lambda ,\Xi \}$ configurations are stable against strong-interaction conversions $\Lambda \to N\overline{K}$ and $\Xi \to N\overline{K}\overline{K}$, confirming and strengthening the conclusion that kaon condensation is unlikely to occur in strong-interaction self-bound strange hadronic matter.

Within the preformed cluster model approach, the values of the preformation factors have been deduced from the experimental cluster decay half-lives assuming that the decay constant of the heavy-ion emission is the product of the assault frequency, the preformation factor and the penetrability. The law according to which the preformation factors follow a simple dependence on the mass of the cluster was confirmed. Then predictions for some of the most possible cluster decays are provided.

For more than 50 years the $\Delta \gamma$ nucleon resonance isobar transition form factors $G_M^{*}(q^2)$, $G_E^{*}(q^2)$, and $G_C^{*}(q^2)$ have been studied experimentally, theoretically, and phenomenologically. Although there has been substantial progress in understanding their behavior, there remains much work to be done. The Δ resonance mass position and width remain ambiguous. A major tool used in many investigations is the Jones-Scadron Δ rest frame parametrization of the three $\Delta N\gamma$ form factors. We point out that many studies utilizing this parametrization and related formulations and which utilize the Δ rest frame (c.m. frame) may not account for Wigner rotations and the consequent helicity mixing that ensues when the Δ is not at rest (lab frame) thus adversely affecting the accurate and precise determination of these form factors.

The spin-flip $M1$ giant resonance is explored in the framework of the random-phase-approximation (RPA) on the basis of the Skyrme energy functional. A representative set of eight Skyrme parametrizations ($\mathrm{SkT}6$, $\mathrm{SkM}*$, $\mathrm{SLy}6$, $\mathrm{SG}2$, $\mathrm{SkO}$, $\mathrm{SkO}’$, $\mathrm{SkI}4$, and $\mathrm{SV}$-bas) is used. Light and heavy, spherical and deformed nuclei (${}^{48}\mathrm{Ca}$, ${}^{158}\mathrm{Gd}$, ${}^{208}\mathrm{Pb}$, and ${}^{238}\mathrm{U}$) are considered. The calculations show that spin densities play a crucial role in forming the collective shift in the spectrum. The interplay of the collective shift and spin-orbit splitting determines the quality of the description. None of the considered Skyrme parametrizations is able to describe simultaneously the $M1$ strength distribution in closed-shell and open-shell nuclei. It is found that the problem lies in the relative positions of proton and neutron spin-orbit splitting. This calls for a better modeling of the tensor and isovector spin-orbit interaction.

For the first time, excited states in ${}^{185}\mathrm{Pb}$ have been observed in in-beam $\gamma$-ray spectroscopic measurements using the recoil-decay tagging method. The resulting level scheme reveals a strongly coupled yrast band structure that originates from coupling of the $i_{13/2}$ quasineutron to a prolate deformed core. The band is also observed to de-excite via the spherical $\alpha$-decaying $13/2^{+}$ isomeric state.

Fifteen strongly oscillating angular distributions of the elastic scattering of ${}^{12}\mathrm{C}+{}^{24}\mathrm{Mg}$ at energies around the Coulomb barrier ($E_{\mathrm{c}.\mathrm{m}.}=10.67\text{−}16.00$ MeV) are reproduced by adding five Breit-Wigner resonance terms to the $l=2,4,6,7$, and 8 elastic $S$ matrix. The nonresonant, background elastic scattering $S$ matrix $S_l^0$ is calculated using the São Paulo potential. The $J=2,4,6,7$, and 8 $\hslash$ molecular resonances fit well into a rotational molecular band, together with other higher lying resonances observed in the ${}^{16}\mathrm{O}+{}^{20}\mathrm{Ne}$ elastic scattering. We propose that the presently observed, largely deformed molecular band corresponds to the hyperdeformed band, which has been found previously in $\alpha$-cluster calculations, as well as in a new Nilsson model calculation. Systematic study of its possible clusterizations predicts the preference of the ${}^{12}\mathrm{C}+{}^{24}\mathrm{Mg}$ and ${}^{16}\mathrm{O}+{}^{20}\mathrm{Ne}$ molecular structure, in accordance with our present results.

A recent analysis of the ${}^{12}\mathrm{C}$$+$${}^{24}\mathrm{Mg}$ scattering [W. Sciani et al., Phys. Rev. C 80, 034319 (2009)] suggests the existence of a hyperdeformed band in the ${}^{36}\mathrm{Ar}$ nucleus, completely in line with the predictions of $\alpha$ [W. D. M. Rae and A. C. Merchant, Phys. Lett. B279, 207 (1992)] and binary cluster calculations [J. Cseh et al., Phys. Rev. C 70, 034311 (2004)]. Here we review the structural understanding of the superdeformed and the hyperdeformed states of ${}^{36}\mathrm{Ar}$ and present new results on the shape isomers as well. Special attention is paid to the clusterization of these states, which indicates the appropriate reaction channels for their formation.