Low-energy proton capture reactions in the mass 55–60 region are studied in a microscopic optical model. The nuclear density profile is calculated using the relativistic mean field theory. The DDM3Y interaction is folded with the theoretical density to obtain the proton-nucleus optical potential. A definite set of normalization parameters has been obtained for the concerned mass region by comparing with all available experimental data in this mass region. These parameters have been used to obtain proton capture rates for astrophysically important reactions in this mass region.

High-spin states in ${}^{138}\mathrm{Nd}$ were investigated by using the ${}^{48}\mathrm{Ca}+{}^{94}\mathrm{Zr}$ reaction and $\gamma$-ray coincidences were acquired with the GASP spectrometer. A rich level scheme was developed including 14 new bands of quadrupole transitions at very high spins. Linking transitions connecting 11 high-spin bands to low-energy states have been observed. Calculations based on the cranked Nilsson–Strutinsky formalism have been used to assign configurations to the observed bands. The main result of these calculations is that all 14 bands exhibit a stable triaxial deformation up to the highest observed spins, giving strong support to the existence of a triaxial minimum with normal deformation and positive asymmetry parameter in nuclei with a few holes in the $N=82$ shell closure.

As a consequence of the chiral anomaly, the hydrodynamics of hot quantum chromodynamics (QCD) matter coupled to quantum electrodynamics allows for a long-wavelength mode of chiral charge density, the chiral magnetic wave (CMW), that provides for a mechanism of electric charge separation along the direction of an external magnetic field. Here, we investigate the efficiency of this mechanism for values of the time-dependent magnetic field and of the energy density attained in the hot QCD matter of ultrarelativistic heavy-ion collisions. To this end, we derive the CMW equations of motion for expanding systems by treating the CMW as a charge perturbation on top of an expanding Bjorken-type background field in the limit $\mu /T\ll 1$. Both, approximate analytical and full numerical solutions to these equations of motion, indicate that for the lifetime and thermodynamic conditions of ultrarelativistic heavy-ion collisions, the efficiency of CMW-induced electric charge separation decreases with increasing center-of-mass energy and that the effect is numerically very small. We note, however, that if sizable oriented asymmetries in the axial charge distribution (that are not induced by the CMW) are present in the early fluid dynamic evolution, then the mechanism of CMW-induced electric charge separation can be much more efficient.

We study the meson-baryon interaction with $J^P=1/2^{-}$ using the hidden-gauge Lagrangians and mixing pseudoscalar meson-baryon with the vector meson-baryon states in a coupled channels scheme with $\pi N,\eta N,K\Lambda ,K\Sigma ,\rho N$, and $\pi \Delta (d$ wave). We fit the subtraction constants of each channel to the $S_{11}$ partial wave amplitude of the $\pi N$ scattering data extracted from the partial wave analysis of the George Washington group. We find two poles that we associate to the $N^{*}\left(1535\right)$ and the $N^{*}\left(1650\right)$ resonances, with negative subtraction constants of natural size, and compare the results with empirical determinations of these pole positions. We calculate the branching ratios for the different channels of each resonance and we find a good agreement with the experimental data. The cross section for the ${\pi }^{-}p\to \eta n$ scattering is also evaluated and compared with experiment.

The structure of hadrons is described well by the Nambu–Jona-Lasinio (NJL) model, which is a chiral effective quark theory of QCD. In this work we explore the electromagnetic structure of the pion and kaon using the three-flavor NJL model in the proper-time regularization scheme, including effects of the pion cloud at the quark level. In the calculation there is only one free parameter, which we take as the dressed light quark ($u$ and $d$) mass. In the regime where the dressed light quark mass is approximately $0.25$ GeV we find that the calculated values of the kaon decay constant, current quark masses, and quark condensates are consistent with experiment- and QCD-based analyses. We also investigate the dressed light quark mass dependence of the pion and kaon electromagnetic form factors, where comparison with empirical data and QCD predictions also favors a dressed light quark mass near $0.25\mathrm{GeV}$.

Nuclear matter under the conditions of a supernova explosion unfolds into a rich variety of spatially structured phases, called nuclear pasta. We investigate the role of periodic networklike structures with negatively curved interfaces in nuclear pasta structures, by static and dynamic Hartree-Fock simulations in periodic lattices. As the most prominent result, we identify for the first time the single gyroid network structure of cubic chiral $I{4}_{1}23$ symmetry, a well-known configuration in nanostructured soft-matter systems, both as a dynamical state and as a cooled static solution. Single gyroid structures form spontaneously in the course of the dynamical simulations. Most of them are isomeric states. The very small energy differences from the ground state indicate its relevance for structures in nuclear pasta.

With the relativistic representation of the nuclear tensor force that is included automatically by the Fock diagrams, we explored the self-consistent tensor effects on the properties of a nuclear matter system. The analysis was performed within the density-dependent relativistic Hartree-Fock (DDRHF) theory. The tensor force is found to notably influence the saturation mechanism, the equation of state, and the symmetry energy of nuclear matter, as well as the neutron star properties. Without introducing any additional free parameters, the DDRHF approach is a natural way to reveal the tensor effects on the nuclear matter system.

Background: Electron scattering provides a powerful tool to determine charge distributions and transition densities of nuclei. This tool will soon be available for short-lived neutron-rich nuclei.

Purpose: Beyond-mean-field methods have been successfully applied to the study of excitation spectra of nuclei in the whole nuclear chart. These methods permit determination of energies and transition probabilities starting from an effective in-medium nucleon-nucleon interaction but without other phenomenological ingredients. Such a method has recently been extended to calculate the charge density of nuclei deformed at the mean-field level of approximation [J. M. Yao et al., Phys. Rev. C 86, 014310 (2012)]. The aim of this work is to further extend the method to the determination of transition densities between low-lying excited states.

Method: The starting point of our method is a set of Hartree-Fock-Bogoliubov wave functions generated with a constraint on the axial quadrupole moment and using a Skyrme energy density functional. Correlations beyond the mean field are introduced by projecting mean-field wave functions on angular momentum and particle number and by mixing the symmetry-restored wave functions.

Results: We give in this paper detailed formulas derived for the calculation of densities and form factors. These formulas are rather easy to obtain when both initial and final states are $0^{+}$ states but are far from being trivial when one of the states has a finite $J$ value. Illustrative applications to ${}^{24}\mathrm{Mg}$ and to the even-mass ${}^{58\text{–}68}\mathrm{Ni}$ have permitted an analysis of the main features of our method, in particular the effect of deformation on densities and form factors. An illustrative calculation of both elastic and inelastic scattering form factors is presented.

Conclusions: We present a very general framework to calculate densities of and transition densities between low-lying states that can be applied to any nucleus. Achieving better agreement with the experimental data will require improving the energy density functionals that are currently used and also introducing quasiparticle excitations in the mean-field wave functions.

Nonthermal nuclear effects triggered in the solar carbon-nitrogen-oxygen (CNO) cycle by fast $\alpha$ particles—products of the $pp$ chain reactions—are examined. The main attention is paid to 8.674-MeV $\alpha$ particles generated in the ${}^7\mathrm{Li}(p,\alpha )\alpha$ reaction. Nonthermal characteristics of these $\alpha$ particles and their influence on some nuclear processes are determined. It is found that the $\alpha$-particle effective temperature is at a level of 1.1 MeV and exceeds the solar core temperature by 3 orders of magnitude. These fast particles are able to significantly enhance some endoergic $(\alpha ,p)$ reactions neglected in standard solar model calculations. In particular, they can substantially affect the balance of the $p+{}^{17}\mathrm{O}\rightleftarrows \alpha +{}^{14}\mathrm{N}$ reactions due to an appreciable increase of the reverse reaction rate. It is shown that in the region $R=0.08\text{–}0.25R_{\odot }$ the reverse $\alpha +{}^{14}\mathrm{N}$ reaction can block the forward $p+{}^{17}\mathrm{O}$ reaction, thus preventing closing of the CNO-II cycle, and increase the ${}^{17}\mathrm{O}$ abundance by a factor of 2–155 depending on $R$. This indicates that the fast $\alpha$ particles produced in the $pp$ cycle can distort running of the CNO cycle, making it essentially different in the inner and outer core regions.

We investigate three-dimensional ideal hydrodynamic evolution, with Landau initial conditions, incorporating event-by-event variation with many events and transverse density inhomogeneities. We show that the transition to boost-invariant flow occurs too late for realistic setups, with corrections of $\mathcal{O}(20\%–30\%)$ expected at freeze-out for most scenarios. Moreover, the deviation from boost invariance is correlated with both transverse flow and elliptic flow, with the more highly transversely flowing regions also showing the most violation of boost invariance. Therefore, if longitudinal flow is not fully developed at the early stages of heavy ion collisions, hydrodynamics where boost invariance holds at midrapidity is inadequate to extract transport coefficients of the quark-gluon plasma. We conclude by arguing that developing experimental probes of boost invariance is necessary, and suggest some promising directions in this regard.

In this Brief Report we derive and present the formulas necessary to correct measurements of cumulants for detection efficiency. In particular we consider the case where the efficiency may depend on the phase space, such as transverse momentum, rapidity, etc.

Within an isospin- and momentum-dependent transport model using as an input nucleon density profiles from Hartree-Fock calculations based on a modified Skyrme-like (MSL) model, I study how to eliminate the influence of neutron-skin size difference of initial colliding nuclei in probing the nuclear symmetry energy. Within the current experimental uncertainty range of the neutron-skin size of ${}^{208}\mathrm{Pb}$, the Pb + Pb collisions are performed in semicentral and peripheral collisions with impact parameters of 5 and 9 fm and at beam energies from 50 to 1000 MeV/nucleon. It is shown that a combination of neutron and proton collective flows, i.e., neutron-proton differential elliptic flow, neutron-proton elliptic flow difference, neutron-proton differential transverse flow, and neutron-proton transverse flow difference, can effectively eliminate the effects of neutron-skin size difference and thus can be useful as sensitive observables in probing nuclear matter symmetry energy in heavy-ion collisions. Moreover, the combined neutron-proton stopping power—including the neutron-proton differential stopping power and neutron-proton stopping power difference—can also eliminate the effects of neutron-skin size difference, and it shows some sensitivities to symmetry energy especially at the lower beam energy.

The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system ${}^{40}\mathrm{Ar}+{}^{197}\mathrm{Au}$, at $b=6$ fm and $E_{\mathrm{beam}}=35$, 50, and $100\mathrm{MeV}/\text{nucleon}$, is investigated by using the improved quantum molecular dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in the projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant neutron to proton yield ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of neutron to proton yield ratio. This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.

Recently the ALICE Collaboration has published a few data of charm hadrons in Pb + Pb collisions at the CERN Large Hadron Collider (LHC). We extend the quark combination to the charm sector to deduce the yield formulas of charm hadrons and point out that the measurement of charm hadron yields can provide important insights into charm quark hadronization mechanism in high energy reactions. We propose several types of yield ratios, e.g., $D^{*+}/D^0,D_s^{+}/D^{+}$, and ${\Lambda }_c^{+}/D_s^{+}$, to measure various properties of low $p_T$ charm quark hadronization. We argue that ratios $D_s^{+}/D^0$ and $2D_s^{+}/(D^0+D^{+})$ as the function of transverse momentum $\left(p_T\right)$ can serve as good probes for the dynamics of charm quark hadronization. We further make predictions for the yields and $p_T$ spectra of identified charm hadrons in central Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV.

We study the electromagnetic contribution to the proton-neutron mass splitting by combining lattice simulations and the modified Cottingham sum rule of Walker-Loud, Carlson, and Miller. This analysis yields an estimate of the isovector nucleon magnetic polarizability as a function of pion mass. The physical value, obtained by chiral extrapolation to the physical pion mass, is ${\beta }_{p\text{−}n}=(-1.12\pm 0.40)\times {10}^{-4}{\mathrm{fm}}^3$, which is in agreement with the empirical result, albeit with a somewhat smaller error. As a result, we find $\delta M_{p\text{−}n}^{\gamma }=1.04\pm 0.11\mathrm{MeV}$, which represents a significant improvement in precision.

Hydrogen burning of the oxygen isotopes takes place in low-mass stars, asymptotic giant branch stars, and classical novae. Observations of oxygen elemental and isotopic abundances in stellar spectra or in presolar grains provide strong constraints for stellar models if reliable thermonuclear reaction rates for hydrogen burning of oxygen are available. We present the results of a new measurement of the ${}^{17}\mathrm{O}{(p,\gamma )}^{18}\mathrm{F}$ reaction in the laboratory bombarding energy range of $170–530$ keV. The measurement is performed with significantly higher beam intensities ($I_{\max }$ $\approx$ 2 mA) compared to previous work and by employing a sophisticated $\gamma$-ray coincidence spectrometer. We measured the cross section at much lower energies than previous in-beam experiments. We also apply a novel data-analysis technique that is based on the decomposition of different contributions to the measured pulse-height spectrum. Our measured strengths of the low-energy resonances amount to $\omega {\gamma }_{\mathrm{pres}}\left(193\mathrm{keV}\right)=(1.86\pm 0.13)\times {10}^{-6}$ eV and $\omega {\gamma }_{\mathrm{pres}}\left(518\mathrm{keV}\right)=(13.70\pm 0.96)\times {10}^{-3}$ eV. For the direct capture $S$ factor at zero energy, we find a value of $S_{\mathrm{DC}}^{\mathrm{pres}}\left(0\right)$ = $4.82\pm 0.41$ keV b. We also present new thermonuclear rates for the ${}^{17}\mathrm{O}+p$ reactions, taking into account all consistent results from previous measurements.

The sources of theoretical uncertainties in the prediction of the two-neutron drip line are analyzed in the framework of covariant density functional theory. We concentrate on single-particle and pairing properties as potential sources of these uncertainties. The major source of these uncertainties can be traced back to the differences in the underlying single-particle structure of the various covariant energy density functionals (CEDF's). It is found that the uncertainties in the description of single-particle energies at the two-neutron drip line are dominated by those existing already in known nuclei. Only approximately one-third of these uncertainties are from the uncertainties in the isovector channel of CEDF's. Thus, improving the CEDF description of single-particle energies in known nuclei will also reduce the uncertainties in the prediction of the position of the two-neutron drip line. The predictions of pairing properties in neutron-rich nuclei depend on the CEDF. Although pairing properties affect moderately the position of the two-neutron drip line they represent only a secondary source for the uncertainties in the definition of the position of the two-neutron drip line.

Wilson coefficients of light four-quark condensates in QCD sum rules are evaluated for pseudoscalar $D$ mesons, thus pushing the sum rules toward mass dimension 6. In contrast to the situation for $\overline{\mathit{q}}\mathit{q}$ mesons, the impact of the four-quark condensates for vacuum as well as in-medium situations is found to be rather small within the Borel window used in previous analyses. The complete four-quark condensate contributions enable us to identify candidates for an order parameter of spontaneous chiral symmetry breaking and/or restoration as well as to evaluate stability criteria of operator product expansions.