The data available from the A2 Collaboration at MAMI were analyzed to select the $\gamma p\to {\pi }^0\eta p$ reaction on an event-by-event basis, which allows for partial-wave analyses of three-body final states to obtain more reliable results, compared to fits to measured distributions. These data provide the world's best statistical accuracy in the energy range from threshold to $E_{\gamma }=1.45$ GeV, allowing a finer energy binning in the measurement of all observables needed for understanding the reaction dynamics. The results obtained for the measured observables are compared to existing models, and the impact from the new data is checked by the fit with the revised Mainz model.

We develop a theoretical framework to quantify the structure of unstable hadron resonances. With the help of the corresponding system in a finite volume, we define the compositeness of resonance states which can be interpreted as a probability. This framework is used to study the structure of the scalar mesons $f_0\left(980\right)$ and $a_0\left(980\right)$. In both mesons, the $\overline{K}K$ component dominates about a half of the wave function. The method is also applied to the $\mathrm{\Lambda }\left(1405\right)$ resonance. We argue that a single energy level in finite volume represents the two eigenstates in infinite volume. The $\overline{K}N$ component of $\mathrm{\Lambda }\left(1405\right)$, including contributions from both eigenstates, is found to be 58%, and the rest is composed of the $\pi \mathrm{\Sigma }$ and other channels.

We use a momentum-dependent optical model potential to analyze the annihilation cross sections of the antineutron $\overline{n}$ on C, Al, Fe, Cu, Ag, Sn, and Pb nuclei for projectile momenta $p_{\mathrm{lab}}$ $\lesssim 500\mathrm{MeV}/c$. We obtain a good description of annihilation cross section data of Barbina et al. [Nucl. Phys. A 612, 346 (1997)] and of Astrua et al. [Nucl. Phys. A 697, 209 (2002)] which exhibit an interesting dependence of the cross sections on $p_{\mathrm{lab}}$ as well as on the target mass number $A$. We also obtain the neutron ($n$) nonelastic reaction cross sections for the same targets. Comparing the $nA$ reaction cross sections ${\sigma }_{\mathrm{rec}}^{nA}$ to the $\overline{n}A$ annihilation cross sections ${\sigma }_{\mathrm{ann}}^{\overline{n}A}$, we find that ${\sigma }_{\mathrm{ann}}^{\overline{n}A}$ is significantly larger than ${\sigma }_{\mathrm{rec}}^{nA}$, that is, the ${\sigma }_{\mathrm{ann}}^{\overline{n}A}/{\sigma }_{\mathrm{rec}}^{nA}$ cross section ratio lies between the values of about 1.5 to 4.0 in the momentum region where comparison is possible. The dependence of the $\overline{n}$ annihilation cross section on the projectile charge is also examined in comparison with the antiproton $\overline{p}$. Here we predict the $\overline{p}A$ annihilation cross section on the simplest assumption that both $\overline{p}A$ and $\overline{n}A$ interactions have the same nuclear part of the optical potential but differ only in the electrostatic Coulomb interaction. Deviation from a such simple model extrapolation in measurements will provide new information on the difference between $\overline{n}A$ and $\overline{p}A$ potentials.

This paper aims at calculating the elastic form factors for a nucleon by considering the extended Regge and modified Gaussian ansatzes based on the generalized parton distributions. To reach this goal, we have considered three different parton distribution functions (PDFs) and have compared the obtained results among them for high momentum transfer ranges. Minimum free parameters have been applied in our parametrization. After achieving the form factors, we calculate the electric radius and the transversely unpolarized and polarized densities for the nucleon. Furthermore, we obtain the impact-parameter-dependent PDFs. Finally, we compare our obtained data with the results of previous studies.

The ${}^{241}\mathrm{Am}(n,\gamma$) cross section has been measured at the n_TOF facility at CERN with the n_TOF ${\mathrm{BaF}}_2$ Total Absorption Calorimeter in the energy range between 0.2 eV and 10 keV. Our results are analyzed as resolved resonances up to 700 eV, allowing a more detailed description of the cross section than in the current evaluations, which contain resolved resonances only up to 150–160 eV. The cross section in the unresolved resonance region is perfectly consistent with the predictions based on the average resonance parameters deduced from the resolved resonances, thus obtaining a consistent description of the cross section in the full neutron energy range under study. Below 20 eV, our results are in reasonable agreement with JEFF-3.2 as well as with the most recent direct measurements of the resonance integral, and differ up to 20–30% with other experimental data. Between 20 eV and 1 keV, the disagreement with other experimental data and evaluations gradually decreases, in general, with the neutron energy. Above 1 keV, we find compatible results with previously existing values.

We compute from chiral two- and three-body forces the complete quasiparticle interaction in symmetric nuclear matter up to twice nuclear matter saturation density. Second-order perturbative contributions that account for Pauli blocking and medium polarization are included, allowing for an exploration of the full set of central and noncentral operator structures permitted by symmetries and the long-wavelength limit. At the Hartree-Fock level, the next-to-next-to-leading order three-nucleon force contributes to all noncentral interactions, and their strengths grow approximately linearly with the nucleon density up to that of saturated nuclear matter. Three-body forces are shown to enhance the already strong proton-neutron effective tensor interaction, while the corresponding like-particle tensor force remains small. We also find a large isovector cross-vector interaction but small center-of-mass tensor interactions in the isoscalar and isovector channels. The convergence of the expansion of the noncentral quasiparticle interaction in Landau parameters and Legendre polynomials is studied in detail.

A nuclear radius of ${}^{22}\mathrm{C}$ is investigated with the total reaction cross sections at medium- to high-incident energies in order to resolve the radius puzzle in which two recent interaction cross-section measurements using ${}^1\mathrm{H}$ and ${}^{12}\mathrm{C}$ targets show the quite different radii. The cross sections of ${}^{22}\mathrm{C}$ are calculated consistently for these target nuclei within a reliable microscopic framework, the Glauber theory. To describe appropriately such a reaction involving a spatially extended nucleus, the multiple scattering processes within the Glauber theory are fully taken into account, that is, the multidimensional integration in the Glauber amplitude is evaluated using a Monte Carlo technique without recourse to the optical-limit approximation. We discuss the sensitivity of the spatially extended halo tail to the total reaction cross sections. The root-mean-square matter radius obtained in this study is consistent with that extracted from the recent cross-section measurement on ${}^{12}\mathrm{C}$ target. We show that the simultaneous reproduction of the two recent measured cross sections is not feasible within this framework.

The experimental measures of the multiplicity derivatives—the moment parameters, the bimodal parameter, the fluctuation of maximum fragment charge number (normalized variance of $Z_{\max }$, or NVZ), the Fisher exponent ($\tau$), and the Zipf law parameter ($\xi$)—are examined to search for the liquid-gas phase transition in nuclear multifragmention processes within the framework of the statistical multifragmentation model (SMM). The sensitivities of these measures are studied. All these measures predict a critical signature at or near to the critical point both for the primary and secondary fragments. Among these measures, the total multiplicity derivative and the NVZ provide accurate measures for the critical point from the final cold fragments as well as the primary fragments. The present study will provide a guide for future experiments and analyses in the study of the nuclear liquid-gas phase transition.

We present the results of an improved Monte Carlo Glauber (MCG) model of relevance for collisions involving nuclei at center-of-mass energies of the BNL Relativistic Heavy Ion Collider ($\sqrt{s_{\mathit{NN}}}=0.2$ TeV), CERN Large Hadron Collider (LHC) ($\sqrt{s_{\mathit{NN}}}=2.76–8.8\mathrm{TeV}$), and proposed future hadron colliders ($\sqrt{s_{\mathit{NN}}}\approx 10–63$ TeV). The inelastic $pp$ cross sections as a function of $\sqrt{s_{\mathit{NN}}}$ are obtained from a precise data-driven parametrization that exploits the many available measurements at LHC collision energies. We describe the nuclear density of a lead nucleus with two separated two-parameter Fermi distributions for protons and neutrons to account for their different densities close to the nuclear periphery. Furthermore, we model the nucleon degrees of freedom inside the nucleus through a lattice with a minimum nodal separation, combined with a “recentering and reweighting” procedure, that overcomes some limitations of previous MCG approaches. The nuclear overlap function, number of participant nucleons and binary nucleon-nucleon collisions, participant eccentricity and triangularity, overlap area, and average path length are presented in intervals of percentile centrality for lead-lead (PbPb) and proton-lead ($p\mathrm{Pb}$) collisions at all collision energies. We demonstrate for collisions at $\sqrt{s_{\mathit{NN}}}=5.02\mathrm{TeV}$ that the central values of the Glauber quantities change by up to 7% in a few bins of reaction centrality, due to the improvements implemented, though typically they remain within the previously assigned systematic uncertainties, while their new associated uncertainties are generally smaller (mostly below 5%) at all centralities than for earlier calculations. Tables for all quantities versus centrality at present and foreseen collision energies involving Pb nuclei, as well as for collisions of XeXe at $\sqrt{s_{\mathit{NN}}}=5.44\mathrm{TeV}$, and AuAu and CuCu at $\sqrt{s_{\mathit{NN}}}=0.2\mathrm{TeV}$, are provided. The source code for the improved Monte Carlo Glauber model is made publicly available.

The equation of state (EOS) of pure neutron matter (PNM) is studied in QCD sum rules (QCDSRs ). It is found that the QCDSR results on the EOS of PNM are in good agreement with predictions by current advanced microscopic many-body theories. Moreover, the higher-order density terms in quark condensates are shown to be important to describe the empirical EOS of PNM in the density region around and above nuclear saturation density although they play a minor role at subsaturation densities. The chiral condensates in PNM are also studied, and our results indicate that the higher-order density terms in quark condensates, which are introduced to reasonably describe the empirical EOS of PNM at suprasaturation densities, tend to hinder the appearance of chiral symmetry restoration in PNM at high densities.

In order to study the correlations between clusters and nucleons in light nuclei, we formulate a new superposed Tohsaki-Horiuchi-Schuck-Röpke (THSR) wave function which describes both spatially large spreading and cluster-correlated dynamics of valence nucleons. Using this new THSR wave function, the binding energy of ${}^9\mathrm{B}$ is significantly improved in comparison with our previous studies. We calculate the excited states of ${}^9\mathrm{B}$ and obtain an energy spectrum of ${}^9\mathrm{B}$ which is consistent with the experimental results. This includes the prediction of the first $1/2^{+}$ excited state of ${}^9\mathrm{B}$ which is not yet fixed experimentally. We study the proton dynamics in ${}^9\mathrm{B}$ and find that the cluster-proton correlation plays an essential role for the proton dynamics in the ground state of ${}^9\mathrm{B}$. Furthermore, we discuss the density distribution of the valence proton with special attention to its tail structure. Finally, the resonance nature of excited states of ${}^9\mathrm{B}$ is illustrated comparing root-mean-square radii between the ground and excited states.

A method is presented to evaluate the particle-phonon coupling (PC) corrections to the single-particle energies in semimagic nuclei, based on the direct solution of the Dyson equation with PC-corrected mass operator. It is used for finding the odd-even mass difference between even Pb and Sn isotopes and their odd-proton neighbors. The Fayans energy density functional DF3-a is used, which gives rather highly accurate predictions for these mass differences already at the mean-field level. In the case of the lead chain, account for the PC corrections induced by the low-lying phonons $2_1^{+}$ and $3_1^{-}$ makes agreement of the theory with the experimental data significantly better. For the tin chain, the situation is not so definite. In this case, the PC corrections make agreement better in the case of the addition mode but they spoil the agreement for the removal mode. We discuss the reason for such a discrepancy.

The ${}^{30}\mathrm{S}(\alpha ,p){}^{33}\mathrm{Cl}$ reaction has been identified in several type-1 x-ray burst (XRB) sensitivity studies as a significant reaction within the $\alpha p$ process, possibly influencing not only the abundances of burst ashes but also the bolometric shape of double-peaked light curves coming from certain XRB systems. Given the dearth of experimental data on the ${}^{30}\mathrm{S}(\alpha ,p)$ ${}^{33}\mathrm{Cl}$ reaction at burst temperatures, we have performed high energy-resolution forward-angle ${}^{36}\mathrm{Ar}(p,t){}^{34}\mathrm{Ar}$ measurements in order to identify levels in ${}^{34}\mathrm{Ar}$ that could appear as resonances in the ${}^{30}\mathrm{S}(\alpha ,p){}^{33}\mathrm{Cl}$ reaction. Energies of levels identified in this work, along with model-based assumptions for spin assignments and spectroscopic factors, were then used to determine a rate for the ${}^{30}\mathrm{S}(\alpha ,p){}^{33}\mathrm{Cl}$ reaction based on a narrow-resonance formalism. The rates determined in this work are then compared with two standard Hauser-Feshbach model predictions over a range of XRB temperatures.

An improved measurement of the ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ lifetime is presented. In this paper, the mesonic decay modes ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}\to {}^3\mathrm{He}$ + ${\pi }^{-}$ and ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}\to d+p+{\pi }^{-}$ are used to reconstruct the ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ from Au+Au collision data collected by the STAR collaboration at Relativistic Heavy Ion Collider (RHIC). A minimum ${\chi }^2$ estimation is used to determine the lifetime of $\tau ={142}_{-21}^{+24}(\mathrm{stat}.)\pm 29(\mathrm{syst}.)$ ps. This lifetime is about 50% shorter than the lifetime $\tau =263\pm 2$ ps of a free $\mathrm{\Lambda }$, indicating strong hyperon-nucleon interaction in the hypernucleus system. The branching ratios of the mesonic decay channels are also determined to satisfy ${\mathrm{B}.\mathrm{R}.}_{({}^3\mathrm{He}+{\pi }^{-})}/({\mathrm{B}.\mathrm{R}.}_{({}^3\mathrm{He}+{\pi }^{-})}+{\mathrm{B}.\mathrm{R}.}_{(d+p+{\pi }^{-})})=0.32\pm 0.05(\mathrm{stat}.)\pm 0.08(\mathrm{syst}.)$. Our ratio result favors the assignment $J\left({}_{\mathrm{\Lambda }}{}^3\mathrm{H}\right)=\frac{1}{2}$ over $J\left({}_{\mathrm{\Lambda }}{}^3\mathrm{H}\right)=\frac{3}{2}$. These measurements will help to constrain models of hyperon-baryon interactions.

In this Rapid Communication, the $2{\beta }^{-}$-decay energies $Q\left(2{\beta }^{-}\right)$ given in the atomic mass evaluation are used to extract not only the quadratic volume symmetry energy coefficient $c_{\mathrm{sym}}^v$, but also the quartic one $c_{\mathrm{sym},4}^v$. Based on the modified Bethe-Weizsäcker nuclear mass formula of the liquid-drop model, the decay energy $Q\left(2{\beta }^{-}\right)$ is found to be closely related to both the quadratic and quartic symmetry energy coefficients $c_{\mathrm{sym}}^v$ and $c_{\mathrm{sym},4}^v$. There are totally 449 data of decay energies $Q\left(2{\beta }^{-}\right)$ used in the present analysis where the candidate nuclei are carefully chosen by fulfilling the following criteria: (1) large neutron-proton number difference $N-Z$, (2) large isospin asymmetry $I$, and (3) limited shell effect. The values of $c_{\mathrm{sym}}^v$ and $c_{\mathrm{sym},4}^v$ are extracted to be 29.345 and 3.634 MeV, respectively. Moreover, the quadratic surface-volume symmetry energy coefficient ratio is determined to be $\kappa =c_{\mathrm{sym}}^s/c_{\mathrm{sym}}^v=1.356$.

It has been proposed recently that a previously unobserved neutron decay branch to a dark matter particle ($\chi$) could account for the discrepancy in the neutron lifetime observed in experiments that use two different measurement techniques. One of the possible final states discussed includes a single $\chi$ along with an $e^{+}{e}^{-}$ pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with $\sim 4\pi$ acceptance using a pair of detectors that observe a volume of stored ultracold neutrons. The summed kinetic energy ($E_{e^{+}{e}^{-}}$) from such events is used to set limits, as a function of the $\chi$ mass, on the branching fraction for this decay channel. For $\chi$ masses consistent with resolving the neutron lifetime discrepancy, we exclude this as the dominant dark matter decay channel at $\gg 5\sigma$ level for $100<E_{e^{+}{e}^{-}}<644\text{keV}$. If the $\chi +e^{+}{e}^{-}$ final state is not the only one, we set limits on its branching fraction of $<{10}^{-4}$ for the above $E_{e^{+}{e}^{-}}$ range at $>90\%$ confidence level.

The available experimental data for the ${}^{20}\mathrm{Ne}+{}^{16}\mathrm{O}$ system in the energy range where the effect of $\alpha$-cluster transfer is well observed are reanalyzed using the cluster folding model. The cluster folding potential, which includes both real and imaginary terms, reproduces the data at forward angles and the inclusion of the ${}^{16}\mathrm{O}({}^{20}\mathrm{Ne},{}^{16}\mathrm{O}){}^{20}\mathrm{Ne}$ elastic transfer process provides a satisfactory description of the backward angles. The spectroscopic factor for the ${}^{20}\mathrm{Ne}\to {}^{16}\mathrm{O}+\alpha$ overlap was extracted and compared with other values from the literature. The present results suggest that the (${}^{20}\mathrm{Ne},{}^{16}\mathrm{O}$) reaction might be an alternative means of exploring the $\alpha$-particle structure of nuclei.

Continuum discretized coupled-channel (CDCC) calculations of total fusion cross sections for reactions induced by the weakly bound nucleus ${}^6\mathrm{Li}$ with targets ${}^{28}\mathrm{Si}, {}^{59}\mathrm{Co}, {}^{96}\mathrm{Zr}, {}^{198}\mathrm{Pt}$, and ${}^{209}\mathrm{Bi}$ at energies around the Coulomb barrier are presented. In the cluster structure frame of ${}^6\mathrm{Li}\to \alpha +d$, short-range absorption potentials are considered for the interactions between the $\alpha$ and $d$ fragments with the targets. The effect of resonance ($l=2, J^{\pi }=3^{+},2^{+},1^{+}$) and nonresonance states of ${}^6\mathrm{Li}$ on fusion is studied by using two approaches: (1) by omitting the resonance states from the full discretized CDCC breakup space and (2) by considering only the resonance subspace. A systematic analysis of the effect on fusion from resonance breakup couplings is carried out from light to heavy mass targets. Among other things, it is found that resonance breakup states produce strong repulsive polarization potentials that lead to fusion suppression. Couplings from nonresonance states give place to weak repulsive potentials at high energies; however, these become attractive for the heavier targets at low energies.

Unconstrained partial -wave amplitudes, obtained at discrete energies from fits to complete sets of eight independent observables, may be used to reconstruct reaction amplitudes. These partial-wave amplitudes do not vary smoothly with energy and are in principle nonunique. We demonstrate how this behavior can be ascribed to the continuum ambiguity. Starting from the spinless scattering case, we show how an unknown overall phase, depending on energy and angle, mixes the structures seen in the associated partial-wave amplitudes. This process is illustrated using a simple toy model. We then apply these principles to pseudoscalar meson photoproduction, showing how the above effect can be removed through a phase rotation, allowing a consistent comparison with model amplitudes. The effect of this phase ambiguity is also considered for Legendre expansions of experimental observables.

Transfer- and fusion-induced fission in inverse kinematics has proved to be a powerful tool to investigate nuclear fission, widening information on the fission fragments and access to unstable fissioning systems with respect to other experimental approaches. An experimental campaign is being carried out at GANIL with this technique since 2008. In these experiments, a beam of ${}^{238}\mathrm{U}$, accelerated to 6.1 MeV/u, impinges on a ${}^{12}\mathrm{C}$ target. Fissioning systems from U to Cf are populated through inelastic scattering, transfer, and fusion reactions, with excitation energies that range from a few MeV up to 46 MeV. The use of inverse kinematics, the SPIDER telescope, and the VAMOS spectrometer allow the characterization of the fissioning system in terms of mass, nuclear charge, and excitation energy, and the isotopic identification of the full fragment distribution. This work reports on new data from the second experiment of the campaign on fission-fragment yields of the heavy actinides ${}^{238}\mathrm{U}, {}^{239}\mathrm{Np}, {}^{240}\mathrm{Pu}, {}^{244}\mathrm{Cm}$, and ${}^{250}\mathrm{Cf}$, which are of interest from both fundamental and application points of view.