A $\overline{K}N\text{−}\pi \mathrm{\Sigma }\text{−}\pi \mathrm{\Lambda }$ coupled-channel potential is constructed on the basis of chiral SU(3) dynamics. Several matching conditions are introduced to formulate an equivalent local potential that reproduces the coupled-channel scattering amplitudes resulting from chiral $\mathrm{SU}{\left(3\right)}_L\times {\mathrm{SU}\left(3\right)}_R$ meson-baryon effective field theory. In contrast to a previously constructed effective single-channel $\overline{K}N$ potential, the explicit treatment of the $\pi \mathrm{\Sigma }$ channel yields a natural description of the low-mass pole as part of the two-pole structure of the $\mathrm{\Lambda }\left(1405\right)$ resonance. The energy dependence of the potential can now be parametrized with a minimum of polynomial orders. To study the properties of the $\mathrm{\Lambda }\left(1405\right)$ as a quantum-mechanical quasibound state, we derive the normalization condition of its wave function generated by the energy-dependent coupled-channel potential, using the Feshbach projection method. This framework provides an improved understanding of this system from the viewpoint of the compositeness of hadrons. With the properly normalized wave function, we demonstrate and confirm that the high-mass pole of the $\mathrm{\Lambda }\left(1405\right)$ is dominated by the $\overline{K}N$ component.

Cross sections of one- and two-neutron removal reactions of ${}^{24}\mathrm{O}$, leading to the ${}^{23}\mathrm{O}(\frac{1}{2}{}^{+}$) ground state and to bound final states of ${}^{22}\mathrm{O}$, have been measured at the National Superconducting Cyclotron Laboratory. The experiment was conducted using the S800 spectrograph and a ${}^{24}\mathrm{O}$ beam energy of 92.3 MeV/u. The measured ${}^{23}\mathrm{O}$ ground state and ${}^{22}\mathrm{O}$ inclusive cross section values, of 74(11) and 146(33) mb, respectively, are in good agreement with calculations using eikonal reaction dynamics and shell-model nuclear structure overlaps. The widths at half maximum of the associated parallel momentum distributions of these cross sections, deduced from Gaussian fits, are 115(13) MeV/$c$ for ${}^{23}\mathrm{O}$ and 309(36) MeV/$c$ for ${}^{22}\mathrm{O}$ in the projectile rest frame. The data and calculations strongly support the shell-model description of ${}^{24}\mathrm{O}$ as a spherical, doubly-magic structure.

An event generator for exclusive simulation of nucleus-nucleus collisions based on quantum molecular dynamics is developed. A comparison of the results obtained using this event generator with earlier measurements show that the yields of pions, kaons, antiprotons, deuterons, and nuclear fragments in the collisions of various nuclei pair such as Si-Al and Pb-Pb in the energy range of a few to $100A$ GeV are predicted successfully. The Lorentz-covariant description of nucleon-nucleon interactions plays a critical role in reproducing fragment yields in peripheral collisions. Secondary meson yields from nucleus-nucleus collisions are well reproduced by incorporating the production and decay of resonances of up to 2 GeV/$c^2$ and strings. This model can therefore be used for analysis and planning of high-energy particle physics experiments, prediction of cosmic ray transport, and shielding design of high-energy heavy-ion accelerators.

We report the first experimental determination of independent isomeric yield ratios using direct ion counting with a Penning trap, which offered such a high resolution in mass that isomeric states could be separated. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyväskylä. The isomer production ratios of ${}^{81}\mathrm{Ge}$, ${}^{96,97}\mathrm{Y}$, ${}^{128,130}\mathrm{Sn}$, and ${}^{129}\mathrm{Sb}$ in the 25-MeV proton-induced fission of ${}^{\mathrm{nat}}\mathrm{U}$ and ${}^{232}\mathrm{Th}$ were studied. Three isomeric pairs (${}^{81}\mathrm{Ge}$, ${}^{96}\mathrm{Y}$, and ${}^{129}\mathrm{Sb}$) were measured for the first time for the ${}^{\mathrm{nat}}\mathrm{U}(p,f$) reaction, while all the reported yield ratios for the ${}^{232}\mathrm{Th}(p,f$) reaction were determined for the first time. The comparison of the experimentally determined isomeric yield ratios with data available in the literature shows a reasonable agreement, except for the case of ${}^{130}\mathrm{Sn}$ for unspecified reasons. The obtained results were also compared with the gef model, where good agreement can be noticed in most cases for both reactions. Serious discrepancies can only be observed for the cases of ${}^{96,97}\mathrm{Y}$ for both reactions. Moreover, based on the isomeric yield ratios, the root-mean-square angular momenta ($J_{\text{rms}}$) of the fission fragments after scission were estimated using the talys code. The experimentally determined isomeric yield ratios, and consequently the deduced $J_{\text{rms}}$, for ${}^{130}\mathrm{Sn}$ are significantly lower compared to ${}^{128}\mathrm{Sn}$ for both fissioning systems. This can be attributed to the more spherical shape of the fragments that contribute to the formation of ${}^{130}\mathrm{Sn}$, due to their proximity to the $N=82$ shell closure. The values of $J_{\text{rms}}$ for ${}^{129}\mathrm{Sb}$ are higher than ${}^{128}\mathrm{Sn}$ for both reactions, despite the same neutron number of both nuclides ($N=78$), indicating the odd-$Z$ effect where fission fragments with odd-$Z$ number tend to bear larger angular momentum than even-$Z$ fragments. The isomer production ratio for the isotopes of Sn is more enhanced in the ${}^{\mathrm{nat}}\mathrm{U}(p,f$) reaction than in ${}^{232}\mathrm{Th}(p,f$). The opposite is observed for ${}^{96}\mathrm{Y}$ and ${}^{97}\mathrm{Y}$. These discrepancies might be associated to different scission shapes of the fragments for the two fission reactions, indicating the impact that the different fission modes can have on the isomeric yield ratios.

The extensive elastic ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ scattering data measured at low energies show consistently an oscillating enhancement of the elastic cross section at backward angles that is difficult to describe within the conventional optical model. Given the significant $\alpha$ spectroscopic factors predicted for the dissociation ${}^{16}\mathrm{O}\to \alpha +{}^{12}\mathrm{C}$ by the shell model (SM) and $\alpha$-cluster model calculations, the contribution of the $\alpha$ transfer channels to the elastic ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ scattering should not be negligible, and is expected to account for the enhanced oscillation of the elastic cross section at backward angles. To reveal the impact of the $\alpha$ transfer, a systematic coupled reaction channels (CRCs) analysis of the elastic ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ scattering has been performed where the multistep couplings between the elastic and inelastic scattering channels and the direct and indirect $\alpha$ transfer channels were treated explicitly, using the real optical potentials and inelastic scattering form factors determined by the double-folding model. We show that a consistent CRC description of the elastic ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ data at different energies can be obtained over the whole angular region, using the $\alpha$ spectroscopic factors determined recently in the large scale SM calculation. The present CRC results are, therefore, of interest not only for the nuclear scattering studies but also provide an important spectroscopic information on the cluster dissociation of ${}^{16}\mathrm{O}$.

Background: Nuclear clustering has been one of the main interests in nuclear physics. In order to probe the $\alpha$ clustering through reaction observables, $\alpha$ transfer and $\alpha$ knockout reactions have been studied. It is very important to probe the $\alpha$ cluster amplitude at nuclear surface since the $\alpha$ spectroscopic factor is not necessarily a direct measure of the $\alpha$ clustering.

Purpose: Our goal is to reveal how the $\alpha$ cluster amplitude is probed through $\alpha$ knockout reactions depending on reaction conditions, e.g., the incident energy.

Method: We consider ${}^{20}\mathrm{Ne}(p,p\alpha ){}^{16}\mathrm{O}$ and ${}^{120}\mathrm{Sn}(p,p\alpha ){}^{116}\mathrm{Cd}$ at 100–400 MeV within the distorted wave impulse approximation (DWIA) framework. We introduce a masking function, which shows how the reaction amplitude in the nuclear interior is suppressed and defines the probed region of the $\alpha$ cluster wave function.

Results: It is clearly shown by means of the masking function that the $\alpha$ knockout reaction probes the $\alpha$ cluster amplitude in the nuclear surface region, which is the direct measure of well-developed $\alpha$ cluster states. The incident energy dependence of the masking effect is investigated, using a simplified form of the masking function.

Conclusions: The $\alpha$ knockout reaction can probe the $\alpha$ cluster amplitude in the nuclear surface region by choosing proper kinematics owing to the masking effect originated from absorptions of distorting potentials, and is a suitable method to investigate how $\alpha$ cluster states are spatially developed.

We study the kinetic freeze-out conditions of bulk hadrons in nuclear collisions. The transverse and longitudinal momentum spectra of the identified hadrons produced in central Au+Au and Pb+Pb collisions, in the beam energy range of $E_{\mathrm{lab}}=2A–158\mathrm{A}$ GeV are analyzed for this purpose, within a generalized non-boost-invariant blast-wave model. The kinetic freeze-out temperature is found to vary in the range of 55–90 MeV, whereas the average transverse velocity of collective expansion is found to be around $0.5c–0.6c$. The mean longitudinal velocity of the fireball is seen to increase monotonically with increasing longitudinal boost. The results would be useful to understanding the gross collision dynamics for the upcoming experiments at the GSI Facility for Antiproton and Ion Research and Nuclotron-based Ion Collider fAcility at JINR.

We present a new mechanism for deep crustal heating in accreting neutron stars. Charged pions (${\pi }^{+}$) are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. For massive and/or compact neutron stars, neutrinos deposit $\approx 1–2\mathrm{MeV}$ of heat per accreted nucleon into the inner crust. The strength of neutrino heating is comparable to the previously known sources of deep crustal heating, such as from pycnonuclear fusion reactions, and is relevant for studies of cooling neutron stars. We model the thermal evolution of a transient neutron star in a low-mass x-ray binary, and in the particular case of the neutron star MXB 1659-29 we show that additional deep crustal heating requires a higher thermal conductivity for the neutron star inner crust. A better knowledge of pion-production cross sections near threshold would improve the accuracy of our predictions.

Background: Given the importance of including nonlocality in the effective interactions in reaction models, a recent phenomenological study focusing on neutron-target nonlocal optical potentials suggests the need for the inclusion of explicit energy dependence [Lovell et al., Phys. Rev. C 96, 051601 (2017)].

Purpose: In this work, we inspect whether the same is true for proton nonlocal optical potentials.

Method: Similarly to the earlier work, we perform a ${\chi }^2$ analysis of proton elastic scattering data on ${}^{40}\mathrm{Ca}$, ${}^{90}\mathrm{Zr}$, and ${}^{208}\mathrm{Pb}$ at energies of $E\approx 10–45$ MeV, assuming the Tian, Pang, and Ma nonlocal form for the optical potential. We introduce energy and asymmetry dependencies in the imaginary part of the potential and refit the data to obtain a global parametrization.

Results: No matter which starting point is used, or whether we include backward angles in the fitting procedure, our results show the emergence of a strong energy dependence in the potential. We also show that while our parametrization represents only a modest improvement over the original energy-independent potential for those cases included in the fit, our new energy-dependent potential extrapolates much better for nuclei not included in the fit and for energies above those included.

Conclusions: As for the neutron case, we conclude that nonlocality alone cannot provide a complete description of proton elastic scattering data and that a significant energy dependence is required.

Background: Different theoretical models have been used to understand the effects of coupling of direct reaction channels on reaction observables in recent years. However, very few attempts have been made to check the consistency of the model calculations in terms of comparing different experimental observables with the model predictions.

Purpose: In the present work, coupled channel calculations are performed with transfer and breakup coupling for collision of the weakly bound stable projectile ${}^6\mathrm{Li}$ with the medium-mass target ${}^{64}\mathrm{Ni}$ at near-barrier energies. The main goal is to find the consistency of the model calculation in simultaneous reproduction of reaction observables like the elastic angular distributions, back-angle elastic excitation function, and fusion excitation function to find the effective energy regions of dominance of these couplings.

Method: Both coupled reaction channel (CRC) and continuum discretized coupled channel (CDCC) calculations are performed using the code fresco. Transfer coupling is included through the CRC formalism. The CDCC scheme is used for breakup coupling and to distinguish the effect of resonant and nonresonant couplings.

Results: In the case of the CRC calculation, the full coupling including inelastic scattering, $1n$ stripping, and $1p$ stripping gives the best description of the experimental data and particularly reproduces the data in the subbarrier energy region. It is observed that the $1p$-transfer channel has a larger impact on reaction observables compared to $1n$ transfer. On the other hand, for breakup nonresonant breakup has the dominant effect on the reaction observables, although resonant breakup has a larger cross section. The full breakup coupling reproduces the elastic scattering angular distributions and excitation function in the above-barrier region. But the scheme overpredicts these observables in the subbarrier region.

Conclusion: CRC and CDCC calculations are complementary to each other. The energy dependencies of the relevant couplings for the ${}^6\mathrm{Li}+{}^{64}\mathrm{Ni}$ system around the barrier show that inelastic and transfer coupling are important at energies below the Coulomb barrier but continuum coupling is dominant in the above-barrier energy region.

The pygmy dipole resonance (PDR) of ${}^{68}\mathrm{Ni}$ was measured by Wieland et al. [Phys. Rev. Lett. 102, 092502 (2009)] through virtual photon scattering and Rossi et al. [Phys. Rev. Lett. 111, 242503 (2013)] through a photoneutron reaction. However, the PDR peaks are observed at different positions: 11 and 9.55(17) MeV respectively. Our calculation based on the deformed relativistic random phase approximation suggests that the discrepancy between these two measurements might be induced by the effect of the shape-coexistence isomeric state in ${}^{68}\mathrm{Ni}$.

Ground-state-to-ground-state neutrinoless double-beta ($0\nu \beta \beta$) decays in nuclei of current experimental interest are revisited. In order to improve the reliability of the nuclear matrix element (NME) calculations for the light Majorana-neutrino mode, the NMEs are calculated by exploiting the newly available data on isovector spin-dipole (IVSD) $J^{\pi }=2^{-}$ giant resonances. In order to correctly describe the IVSD up to and beyond the giant-resonance region, the present computations are performed in extended no-core single-particle model spaces using the spherical version of the proton-neutron quasiparticle random-phase approximation (pnQRPA) with two-nucleon interactions based on the Bonn one-boson-exchange $G$ matrix. The appropriate short-range correlations, nucleon form factors, higher-order nucleonic weak currents, and partial restoration of the isospin symmetry are included in the calculations. The results are compared with earlier calculations of Hyvärinen and Suhonen [Phys. Rev. C 91, 024613 (2015)] performed in much smaller single-particle bases without access to the IVSD $J^{\pi }=2^{-}$ giant-resonance data reported here.

The distribution of flow harmonics in heavy-ion experiment can be characterized by standardized cumulants. We first model the ellipticity and power parameters of the elliptic-power distribution by employing MC-Glauber model. Then we use the elliptic-power distribution together with the hydrodynamic linear response approximation to study the two dimensional standardized cumulants of elliptic and triangular flow ($v_2$ and $v_3$) distribution. For the second harmonic, it turns out that finding two-dimensional cumulants in terms of $2q$-particle correlation functions $c_2\left\{2q\right\}$ is limited to the skewness. We also show that $c_3\left\{2\right\},c_3\left\{4\right\}$, and $c_3\left\{6\right\}$, are related to the second, fourth, and sixth standardized cumulants of the $v_3$ distribution, respectively. The cumulant $c_n\left\{2q\right\}$ can be also written in terms of $v_n\left\{2q\right\}$. Specifically, $-{(v_3\left\{4\right\}/v_3\left\{2\right\})}^4$ turns out to be the kurtosis of the $v_3$ event-by-event fluctuation distribution. We introduce a new parametrization for the distribution $p\left(v_3\right)$ with $v_3\left\{2\right\}$, kurtosis and sixth-order standardized cumulant being its free parameters. Compared to the Gaussian distribution, it indicates a more accurate fit with experimental results. Finally, we compare the kurtosis obtained from simulation with that of extracted from experimental data for the $v_3$ distribution.

The present work investigates the uncertainties in a nuclear liquid-drop model. The model parameters, their uncertainties and correlations, are determined through standard regression analysis that includes a statistical treatment of the errors of the model. The adjustment of the model is based on experimental binding energies corrected by the Thomas-Fermi shell corrections. The uncertainties are then propagated onto observables to reveal the reliability of the predictions and insight is provided to guide further research. Standard regression analysis is further extended to encompass experimental uncertainties as well as correlations. Strong support for such an extension can be found in Bayesian inference. The uncertainties and the correlations regarding microscopic corrections are not currently known; however, when available, these contributions may be included through this extended formalism.

Continuum spectra of hadrons scattered without charge exchange by complex nuclei, under conditions such that incoherent elastic scattering from bound nucleons can be considered as quasifree, have been transformed into relativistic single-nucleon responses, in a fashion familiar for electron spectra. These hadron responses are subjected to tests of their scaling properties, for changes in momentum transfer, nuclear mass, and specific hadron beams. Scaling is indeed found for some beam energies and angles, with more success for light nuclei.

We study the local structure of the vorticity field and the $\mathrm{\Lambda }$ polarization in Au+Au collisions in the energy range $\sqrt{s_{\mathrm{NN}}}=7.7–200\mathrm{GeV}$ and Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2760\mathrm{GeV}$ using a multiphase transport model. We focus on the vorticity field arising from the nonuniform expansion of the fireball, which gives the circular structure of the transverse vorticity ${\mathbf{\omega }}_{\perp }=({\omega }_x,{\omega }_y)$ around the $z$ direction as well as the quadrupole pattern of the longitudinal vorticity ${\omega }_z$ in the transverse plane. As a consequence, the three components of the polarization vector $\mathbf{P}=(P_x,P_y,P_z)$ for $\mathrm{\Lambda }$ hyperons show harmonic behaviors as $\mathrm{sgn}\left(Y\right)sin{\varphi }_p$, $-\mathrm{sgn}\left(Y\right)cos{\varphi }_p$, and $-sin\left(2{\varphi }_p\right)$, where ${\varphi }_p$ and $Y$ are the azimuthal angle and rapidity in momentum space. These patterns of the local $\mathrm{\Lambda }$ polarization are expected to be tested in future experiments.

We present results for charge form factors, the point-proton, charge, and single-nucleon momentum distributions of ${}^4\mathrm{He}$ and ${}^{16}\mathrm{O}$ obtained within the self-consistent Green's function approach. The removal of the center-of-mass contribution for both nuclei has been performed by using a metropolis Monte Carlo algorithm in which the center-of-mass coordinate can be exactly subtracted from the optimal reference state wave function generated during the self-consistent Green's function calculations. The spectral functions of the same two nuclei have been used to compute inclusive electron-nucleus cross sections. The formalism adopted is based on the factorization of the spectral function and the nuclear transition matrix elements. This allows us to provide an accurate description of nuclear dynamics and to account for relativistic effects in the interaction vertex. When final-state interactions for the struck particle are accounted for, we find nice agreement between the data and the theory for the inclusive electron-${}^{16}\mathrm{O}$ cross section. The results lay the foundations for future applications of the self-consistent Green's function method, in both closed and open shell nuclei, to neutrino data analysis.

Using the isospin-dependent quantum molecular dynamics (IQMD) model, a study on the fragmentation of isotopic, isobaric, and isotonic reacting partners is presented. The partitioning of the fragmenting system into gas (low density) and liquid (high density) phases in semicentral collisions of medium mass systems is investigated at various beam energies ranging between 100 and 400 MeV/nucleon. Our findings revealed a crossover of gas/liquid content with the beam energy and the energy where gas and liquid content become equal is labeled as cross-over energy. The influence of isospin degree of freedom (via nuclear symmetry energy, Coulomb potential, and nucleon-nucleon scattering cross section) on the cross-over energy is investigated in detail and our study revealed the dominant role of symmetry potential over the other two isospin effects. Our study also concludes that cross-over energy can act as a sensitive probe of density dependence of nuclear symmetry energy at suprasaturation densities.

Study of the scattering process in the nonlocal interaction framework leads to an integro-differential equation. The purpose of the present work is to develop an efficient approach to solve this integro-differential equation with high degree of precision. The method developed here employs a Taylor approximation for the radial wave function which converts the integro-differential equation into a readily solvable second-order homogeneous differential equation. This scheme is found to be computationally efficient by a factor of 10 when compared to the iterative scheme developed in Upadhyay et al. [J. Phys. G: Nucl. Part. Phys. 45, 015106 (2018)]. The calculated observables for neutron scattering off ${}^{24}\mathrm{Mg}$, ${}^{40}\mathrm{Ca}$, ${}^{100}\mathrm{Mo}$, and ${}^{208}\mathrm{Pb}$ with energies up to 10 MeV are found to be within at most $8\%$ of those obtained with the iterative scheme. Further, we propose an improvement over the Taylor scheme that brings the observables so close to the results obtained by iterative scheme that they are visually indistinguishable. This is achieved without any appreciable change in the run time.

Ion-ion collisions at relativistic energies have been shown recently to be a promising technique for the production of hypernuclei. In this article, we further investigate the production of light $\mathrm{\Lambda }$ hypernuclei by use of a hybrid dynamical model: cascade coalescence followed by Fermi breakup. The predictions are then compared with the available experimental data. The dependence of the production cross section on the beam energy, beam mass number, as well as different projectile-target combinations is investigated. In particular, we evaluate the yields and signal-over-background ratio in the invariant-mass spectrum for carbon projectiles impinging on hydrogen and carbon targets and various coincidence conditions in the experiment using the theoretical calculation as an input. It is found that, comparing with the carbon target, the hydrogen target also leads to sizable hypernuclear yields, even for exotic species, and the hydrogen target could improve significantly the signal-over-background ratio in some hypernuclear invariant mass studies.