We report on a model for determining spin-spin terms in the optical potential for elastic scattering of a nucleon from a target with nonzero spin. These terms are constructed microscopically by folding a realistic effective nucleon-nucleon interaction, which includes both direct and exchange parts, over the ground state of the target nucleus wave function to generate a nucleon-nucleus potential. The resulting spin-spin tensors are evaluated within DWBA. This general model has been used for the specific calculation of polarization transfer coefficient $D_{NN}$, which is unity if there are no spin-spin terms in the optical potential. We have calculated $D_{NN}$ for the elastic scattering of 200 MeV protons from ${}^{10}$B, for which relevant experimental data exist. In our model, the folding formalism leads to both local and nonlocal spin-spin tensor interactions, with higher order couplings in the projectile and target spin that have not been explicitly considered before. We have found that the spin-spin interactions derived from this model have a significant effect on the deviation of $D_{NN}$ from unity, particularly those derived from the tensor exchange term in the $NN$ interaction. The calculation of $D_{NN}$ has also been shown to be particularly sensitive to the parameters of the model used to describe the nuclear structure.

The near-yrast structure of the near-magic, odd-odd nucleus, ${}_{39}^{88}$Y${}_{49}$, has been studied into the high-spin regime. Investigations were performed at the Wright Nuclear Structure Laboratory, Yale University, using the ${}^{74}$Ge(${}^{18}$O,$p3n$) and ${}^{76}$Ge(${}^{18}$O,$p5n$) fusion-evaporation reactions at beam energies of 60 and 90 MeV, respectively. Gamma-ray energy coincidence analyses using both double (${\gamma }^2$) and triple (${\gamma }^3$) fold coincidences, together with angular correlation measurements, have been used to extend the previously reported level scheme to an excitation energy of 8.6 MeV and a spin and parity of 19${}^{(-)}$. The presented level scheme is compared with predictions of a truncated valence space shell-model calculation, which assumes an inert ${}^{56}$Ni core with proton and neutron excitations allowed within the $f_{5/2}$, $p_{3/2}$, $p_{1/2}$, and $g_{9/2}$ single-particle states. The shell-model calculations show a reasonable comparison with the experimental data for the yrast, positive-parity states up to spin 18 $\hslash$, with larger variations evident for negative-parity states with spins greater than 16 $\hslash$. In spite of a significant increase in angular momentum input associated with the thin target ${}^{76}$Ge(${}^{18}$O,$p5n$) reaction channel, as compared to the backed target data using the ${}^{74}$Ge target, no additional discrete states were identified in the former data set, suggesting that the level scheme for this nucleus fragments significantly above the observed states, possibly indicating cross-shell excitations becoming dominant for $I>$19 $\hslash$.

We investigate the $\Lambda \left(1520\right)$ hadronic production in the $pp\to p{K}^{+}\Lambda \left(1520\right)$ and ${\pi }^{-}p\to K^0\Lambda \left(1520\right)$ reactions within the effective Lagrangian method. For the ${\pi }^{-}p\to K^0\Lambda \left(1520\right)$ reaction, in addition to the “background” contributions from $t$-channel $K^{*}$ exchange, $u$-channel ${\Sigma }^{+}$ exchange, and $s$-channel nucleon pole terms, we also consider the contribution from the nucleon resonance $N^{*}\left(2080\right)$ (spin-parity $J^P=3/2^{-}$), which has significant coupling to the $K\Lambda \left(1520\right)$ channel. We show that the inclusion of the $N^{*}\left(2080\right)$ leads to a fairly good description of the low-energy experimental total cross section data of the ${\pi }^{-}p\to K^0\Lambda \left(1520\right)$ reaction. From fitting to the experimental data, we get the $N^{*}\left(2080\right)N\pi$ coupling constant $g_{N^{*}\left(2080\right)N\pi }=0.14\pm 0.04$. By using this value, and with the assumption that the excitation of $N^{*}\left(2080\right)$ is due to the ${\pi }^0$-meson exchanges, we calculate the total and differential cross sections of the $pp\to p{K}^{+}\Lambda \left(1520\right)$ reaction. We also demonstrate that the invariant mass distribution and the Dalitz plot provide direct information of the $\Lambda \left(1520\right)$ production, which can be tested by future experiments.

Recent data show that both the 2${}^{+}$ and 4${}^{+}$ levels in the even neutron-rich Cr and Fe isotopes decrease in excitation energy toward $N=40$. This observation, along with Coulomb excitation and lifetime data, strongly indicates an increase in collectivity near $N=40$ in contradiction with expectations based on first principles. A straightforward two-band mixing model is used to investigate the structure of these neutron-rich Cr and Fe nuclei. The approach takes advantage of the extensive data available for ${}^{60}$Fe to provide the parameter values with which to reproduce the experimental observations in the ${}^{58-64}$Cr and ${}^{60-68}$Fe isotopic chains. Comparisons between the model and the data suggest marked structural differences for the ground-state configurations of $N=40$ Cr and Fe.

Decay properties of the very neutron-deficient isotopes ${}^{197–199}$Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the $2n–4n$ evaporation channels of the fusion-evaporation reaction ${}^{60}$Ni+${}^{141}$Pr $\to$ ${}^{201}$Fr*. Improved $\alpha$-decay properties of ${}^{199}$Fr were determined and the possible existence of two $\alpha$-decaying states in this nucleus is discussed. For the isotope ${}^{198}$Fr a broad $\alpha$-decay energy distribution was detected in the range of $(7470–7930)$ keV and two $\alpha$-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope ${}^{197}$Fr was identified based on the observation of one $\alpha$-decay chain yielding $E_{\alpha }=7728\left(15\right)$ keV and $T_{1/2}=0.6_{-0.3}^{+3.0}$ ms. The systematics of reduced $\alpha$-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes.

Background: ${}^{86}$Kr${}_{50}$ is a neutron-rich nucleus amenable to shell-model calculations due to the shell closure at $N=50$. It is also produced as a fragment in the fissioning of actinides.

Purpose: The level structure of ${}^{86}$Kr at low excitation energies needs additional investigation for detailed comparison with calculations from theoretical models. By determining the cross sections for transitions that feed directly the ground state of ${}^{86}$Kr, a large fraction of the total cross section for the ${}^{86}$Kr${(n,n^{\prime })}^{86}$Kr reaction channel can be obtained.

Methods: Low-spin states of ${}^{86}$Kr were populated in the ${}^{86}$Kr$(n,n^{\prime }\gamma )$ reaction and were studied with the Germanium Array for Neutron-Induced Excitations (GEANIE) spectrometer. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center's (LANSCE) WNR facility provided neutrons in the energy range from 1 to above 600 MeV. The time-of-flight technique was used to determine the incident-neutron energies.

Results: Partial $\gamma$-ray cross sections were measured for 21 $\gamma$ rays of ${}^{86}$Kr and for neutron energies 1 MeV $<E_n<20$ MeV. A large part of the total cross section for the ${}^{86}$Kr${(n,n^{\prime })}^{86}$Kr reaction is observed. Ten new transitions are observed and placed on the level scheme at excitation energies below 3.7 MeV, doubling the number of placed transitions up to this excitation energy. These transitions de-excite five previously known levels, among them the second and third 0${}^{+}$ states, and one new level. The excitation energy of these levels was more accurately determined and the relative intensities of their decay paths were measured. All previously known levels up to 3.7-MeV excitation energy were identified, and the new level was added at 2917-keV excitation energy. Predictions from shell-model calculations are compared with the data.

The elastic scattering of ${}^8$B by a ${}^{\mathrm{nat}}$Pb target was measured at an incident energy of 170.3 MeV. Special care was taken with the limited intensity and broad profile of the secondary beam. The measured angular distribution of the differential cross section shows that the Coulomb-nuclear interference peak (CNIP) is not suppressed in this system, in contrast to what was observed in the scattering of neutron halo nuclei by heavy targets at energies around the Coulomb barrier. Analyses of the angular distribution were performed both in terms of the optical model using a single-folding-type potential and the continuum discretized coupled-channels (CDCC) method, which explicitly takes into account the breakup-channel couplings to the elastic scattering. The overall pattern of the differential cross section is well reproduced by the CDCC calculations. The calculations show that the effect of breakup-channel couplings on the elastic scattering is small in the present case.

We consider the $\Lambda N\to NN$ weak transition, responsible for a large fraction of the nonmesonic weak decay of hypernuclei. We follow the previously derived effective field theory and compute the next-to-leading one-loop corrections. Explicit expressions for all diagrams are provided, which result in contributions to all relevant partial waves.

Stimulated by the proton size puzzle and the proposal of $\mu p$ scattering at the Paul Scherrer Institute (PSI), we study the two-photon exchange corrections to the massive-lepton–proton scattering. The leptonic helicity broken caused by lepton mass introduces new form factors. We estimate the two-photon exchange corrections to these form factors as well as to the unpolarized differential cross sections.

Background: The reaction ${}^{18}$O${(\alpha ,n)}^{21}$Ne is a part of the reaction chains leading to the production of ${}^{19}$F and ${}^{22}$Ne during He burning in low-mass and massive AGB stars, respectively. Additionally, it has been observed as a strong background source in the measurement of other $(\alpha ,n)$ reactions.

Purpose: Previously low-energy ${}^{18}$O${(\alpha ,n)}^{21}$Ne cross section data have only been available in a non-peer-reviewed form. An improved measurement of this reaction has been done to both clarify its astrophysical influence as well as to provide background yield data for future $(\alpha ,n)$ experiments.

Method: The ${}^{18}$O$(\alpha ,n_{(0+1)})$ reaction has been measured with a moderating neutron detector. In addition the $(\alpha ,n_1\gamma )$ channel has been measured independently by observation of the characteristic 350.7 keV $\gamma$ transition in ${}^{21}$Ne. The reaction cross section at energies above $E_{\alpha }=1100$ keV was determined by a simultaneous $R$-matrix fit to both channels. The strengths of the two lowest-energy resonances at $E_{\alpha }=959$ keV and $E_{\alpha }=1066$ keV were analyzed separately using individual Breit-Wigner fits.

Results: The cross section of both reaction channels, ${}^{18}$O${(\alpha ,n_0)}^{21}$Ne and ${}^{18}$O${(\alpha ,n_1\gamma )}^{21}$Ne, was determined from the threshold energies at 851 keV and 1280 keV, respectively, to 2300 keV. A new reaction rate has been deduced for the temperature range of 0.1 GK to 10 GK. A previously reported resonance at $E_{\alpha }=888$ keV is explained as background from the contaminant reaction ${}^{17}$O${(\alpha ,n)}^{20}$Ne.

Conclusions: In general, our reaction rate is slightly lower than the reaction rates in recent compilations. At temperatures below 0.2 GK the present rate is significantly lower because it could be shown that the lowest reported resonance is background from the reaction ${}^{17}$O${(\alpha ,n)}^{20}$Ne that has been wrongly assigned to ${}^{18}$O${(\alpha ,n)}^{21}$Ne.

Using the isospin-dependent quantum molecular dynamics (IQMD) model, the sensitivity of isospin ratios from projectile and target fragmentation towards the density-dependent symmetry energy for the neutron-rich reaction systems ${}^{40,48}$Ca${+}^{58,64}$Ni at 50 and 600 MeV/nucleon has been studied. The kinetic energy spectra of neutron-to-proton single and double ratios are elaborated in detail. The neutron-to-proton double ratio in neutron-rich projectile fragmentation is provided as a useful tool for the density dependence of symmetry energy near the subsaturation density. The sensitivity of the kinetic energy spectra of isospin ratios towards the isospin effect or symmetry energy reduces at suprasaturation density because of secondary nucleon-nucleon collisions.

The decay of various isotopes of Pt${}^{*}$ formed using stable and neutron-rich radioactive beams of Sn is studied by using the dynamical cluster-decay model (DCM). The entrance channel effect in ${}^{190}$Pt${}^{*}$ compound nuclei is investigated using different targets and projectiles. For both entrance channels, i.e., ${}^{132}$Sn+${}^{58}$Ni and ${}^{126}$Sn+${}^{64}$Ni, the fragmentation potential and preformation probability of decaying fragments are almost identical at comparable center-of-mass energies ($E_{\mathrm{c}.\mathrm{m}.}$), enabling us to conclude that decay of ${}^{190}$Pt${}^{*}$ is independent of its formation effects. In order to check for the persistence of entrance channel independence in the decay of Pt${}^{*}$ compound nuclei, various versions of nuclear proximity potentials and different values of level density parameter are employed in the calculations, and the results are sustained. It is also observed that, with inclusion of deformation effects up to quadrupole (${\beta }_2$) within the optimum orientation approach, the structure of potential energy surfaces changes significantly. Besides this, the fission mass distribution of Pt${}^{*}$ isotopes is investigated and consequently the barrier modification is estimated to account for the phenomena of fusion hindrance. The ${}^{132}$Sn+${}^{58}$Ni reaction is also studied using four proximity potentials, i.e., Prox 1977, Prox 1988, mod-Prox 1988, and Denisov 2002 within the framework of the $\ell$-summed extended-Wong model for addressing the fusion hindrance phenomena. We find that Prox 77 and Prox 88 fit the total fusion cross-section data only at above-barrier energies, whereas Denisov 2002 underestimates the data at all energies due to being least sensitive towards asymmetry and isospin. So a stronger nuclear interaction potential mod-Prox 1988 that accounts for isospin effect and asymmetry of the colliding nuclei is employed, which fits the data with smooth variation of ${\ell }_{\max }$($E_{\mathrm{c}.\mathrm{m}.}$). Our calculations indicate that the isospin and asymmetry of colliding nuclei also play an important role in the fusion dynamics, particularly in the below-barrier region.

Background: Strong jet quenching has been observed in heavy ion collisions at both the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) that can be understood through substantial jet energy loss in the created hot QCD matter. Yet the azimuthal anisotropy of jet quenching has not been thoroughly studied in the presence of strong fluctuations in the initial condition.

Purpose: We present with full details a systematic quantification of the hard probe azimuthal response to the geometry and fluctuations of the hot QCD matter at both RHIC and LHC. We also examine the hard-soft dihadron correlation arising from the hard and soft sectors’ responses to the common fluctuating initial condition.

Methods: An even-by-event Monte Carlo simulation is employed. Different geometrical jet-quenching models are tested. The azimuthal anisotropy of jet quenching is extracted and decomposed as harmonic responses (for $n=1$–6) to the corresponding harmonics in the initial state.

Results: We show that such jet response harmonics are sensitive to the jet quenching models as well as to the initial composition of bulk matter. Their centrality dependence puts a strong constraint on the path-length and medium-density dependence of jet energy loss. The computed hard-soft dihadron correlation shows a strong peak on the near side in RHIC central collisions. The triggered correlation in noncentral collisions is also presented.

Conclusions: Only the jet-quenching model with near-$T_c$ enhancement survives the second-harmonic test by the RHIC and LHC. Other harmonics in this model are consistent with the available data. We also demonstrate that the experimentally observed “hard ridge” can be explained in our calculation and that its trigger-azimuthal-angle and associate-$p_t$ dependence could also be qualitatively understood.

We investigate the effect of electric and color charge neutrality on the two-flavor color superconducting (2SC) phase of cold and dense quark matter in presence of constant external magnetic fields and at moderate baryon densities. Within the framework of the Nambu–Jona-Lasinio (NJL) model, we study the interdependent evolution of the quark's BCS gap and constituent mass with increasing density and magnetic field. While confirming previous results derived for the highly magnetized 2SC phase with color neutrality alone, we obtain new results as a consequence of imposing charge neutrality. In the charge neutral gapless 2SC phase (g2SC), a large magnetic field drives the color superconducting phase transition to a crossover, while the chiral phase transition is first order. At larger diquark-to-scalar coupling ratio $G_D/G_S$, where the 2SC phase is preferred, we see hints of the Clogston-Chandrasekhar limit at a very large value of the magnetic field ($B\sim {10}^{19}$G), but this limit is strongly affected by Shubnikov de Haas–van Alphen oscillations of the gap, indicating the transition to a domain-like state.

With the nucleon-pair approximation, we study low-lying structures of three $N=74$ isotones, ${}^{128}$Xe, ${}^{130}$Ba, and ${}^{132}$Ce, and focus on their $K^{\pi }=8^{-}$ isomers. Negative-parity spin-$3\hslash$ and spin-$8\hslash$ pairs are introduced to construct negative-parity eigenstates. Our calculation well reproduces low-lying energy spectra and the electromagnetic properties of the $K^{\pi }=8^{-}$ isomers. Calculated wave functions of $K^{\pi }=8^{-}$ isomers agree with the previous conjecture, that these isomers are given by a two-quasiparticle excitation, ${(\nu {\frac{7}{2}}^{+}\left[404\right]\otimes \nu {\frac{9}{2}}^{-}\left[514\right])}^{\left(8\right)-}$. We discuss the effect of the $\nu g_{7/2}$ single-particle energy evolution on the structure of the $K^{\pi }=8^{-}$ isomer, and predict a similar isomeric mechanism in $N<73$ even-even isotones. The $3_1^{-}$, $5_1^{-}$, and $7_1^{-}$ states of ${}^{130}$Ba and ${}^{132}$Ce are interpreted in terms of octupole vibration or quadrupole-octupole coupling.

The electric dipole moment of a neutral atom is mainly induced by the nuclear Schiff moment. The nuclear wave functions beyond mean-field theories are calculated in terms of the nuclear shell model, which contains two-body interactions violating parity and time-reversal invariance. Using wave functions thus obtained, the Schiff moments for the lowest $1/2^{+}$ states of Xe isotopes are calculated. The upper limit for the electric dipole moment of the ${}^{129}$Xe neutral atom is estimated using its nuclear Schiff moment.

Knowledge of the exact microscopic structure of the 0${}_1$${}^{+}$ ground state and first excited 0${}_2$${}^{+}$ state in ${}^{150}$Sm is required to understand the branching of double β decay to these states from ${}^{150}$Nd. The detailed spectroscopy of ${}^{150}$Sm and ${}^{152}$Gd has been studied using (α,xn) reactions and the γ-ray arrays AFRODITE and JUROGAM II. Consistently strong $E$1 transitions are observed between the excited $K^{\pi }$ $=$ 0${}_2$${}^{+}$ bands and the lowest negative parity bands in both nuclei. These results are discussed in terms of the possible permanent octupole deformation in the first excited $K^{\pi }$ $=$ 0${}_2$${}^{+}$ band and also in terms of the “tidal wave” model of Frauendorf.

The three ${\rm Y}$ states, ${\rm Y}(1S+2S+3S)$, are measured in $d+\text{Au}$ and $p+p$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV and rapidities $1.2<\left|y\right|<2.2$ by the PHENIX experiment at the Relativistic Heavy Ion Collider. Cross sections for the inclusive ${\rm Y}(1S+2S+3S)$ production are obtained. The inclusive yields per binary collision for $d+\text{Au}$ collisions relative to those in $p+p$ collisions ($R_{d\mathrm{Au}}$) are found to be $0.62\pm 0.26\left(\mathrm{stat}\right)\pm 0.13\left(\mathrm{syst}\right)$ in the gold-going direction and $0.91\pm 0.33\left(\mathrm{stat}\right)\pm 0.16\left(\mathrm{syst}\right)$ in the deuteron-going direction. The measured results are compared to a nuclear-shadowing model, EPS09 [Eskola et al., J. High Energy Phys. 04 (2009) 065], combined with a final-state breakup cross section, ${\sigma }_{\mathrm{br}}$, and compared to lower energy $p+A$ results. We also compare the results to the PHENIX $J/\psi$ results [Adare et al., Phys. Rev. Lett. 107, 142301 (2011)]. The rapidity dependence of the observed ${\rm Y}$ suppression is consistent with lower energy $p+A$ measurements.

Elastic and semileptonic transition form factors for the kaon and pion are calculated using the leading order in a global-symmetry-preserving truncation of the Dyson-Schwinger equations and a momentum-independent form for the associated kernels in the gap and Bethe-Salpeter equations. The computed form factors are compared both with those obtained using the same truncation but an interaction that preserves the one-loop renormalization-group behavior of QCD and with data. The comparisons show that in connection with observables revealed by probes with $|Q^2|\lesssim M^2$, where $M\approx 0.4$GeV is an infrared value of the dressed-quark mass, results obtained using a symmetry-preserving regularization of the contact interaction are not realistically distinguishable from those produced by more sophisticated kernels, and available data on kaon form factors do not extend into the domain whereupon one could distinguish among the interactions. The situation differs if one includes the domain $Q^2>M^2$. Thereupon, a fully consistent treatment of the contact interaction produces form factors that are typically harder than those obtained with QCD renormalization-group-improved kernels. Among other things also described are a Ward identity for the inhomogeneous scalar vertex, similarity between the charge distribution of a dressed $u$ quark in the $K^{+}$ and that of the dressed $u$ quark in the ${\pi }^{+}$, and reflections upon the point whereat one might begin to see perturbative behavior in the pion form factor. Interpolations of the form factors are provided, which should assist in working to chart the interaction between light quarks by explicating the impact on hadron properties of differing assumptions about the behavior of the Bethe-Salpeter kernel.