Background: Experimental and theoretical studies of nuclear reaction mechanism to understand relative contribution in large $\alpha$ production due to breakup, incomplete fusion, and transfer reactions induced by weakly bound projectiles near Coulomb barrier are important.

Purpose: Measurement of angular distributions and energy spectra of $\alpha$ and deuterons through breakup, transfer, and incomplete fusion processes to disentangle their relative contributions and to investigate relative importance of breakup-fusion compared to transfer.

Methods: Inclusive $\alpha$ production cross sections have been measured for the ${}^6\mathrm{Li}+{}^{51}\mathrm{V}$ system near Coulomb barrier energies. Theoretical calculations for estimation of various reaction channels contributing to $\alpha$ production have been performed with a finite-range coupled reaction method using FRESCO code. The cross sections from noncapture breakup ($\alpha$ $+$ $d$) and $1n$, $1p$, and $1d$ transfer channels, compound nuclear decay channels, and incomplete fusion leading to $\alpha$ production were estimated to get the cumulative production cross sections.

Results: Contributions from breakup, transfer, and incomplete fusion channels could reproduce the integral direct $\alpha$ production cross sections and their angular distributions quite well. The direct $\alpha$ production cross sections are in agreement with other targets. The $\alpha$ production cross sections are higher compared to the deuteron production.

Conclusions: Kinematic analysis of the energy spectra of $\alpha$ particles and deuterons suggest that $\alpha$ particle spectra is dominated by breakup fusion and deuteron spectra have contribution of breakup and transfer reactions. A systematic study of direct $\alpha$ production with various targets follow a universal behavior on average but noticeable differences are observed for different targets. A ratio of $\alpha$ and deuteron yields for a wide mass range of targets shows a saturation above barrier and an increasing production of $\alpha$ particles relative to deuteron around Coulomb barrier.

Motivated by the recent experimental measurements of differential cross sections of the ${\mathrm{\Sigma }}^{-}p$ elastic scattering in the momentum range of 470 to $850\mathrm{MeV}/c$ by the J-PARC $\mathrm{E}40$ experiment, we extend our previous studies of $S=-1$ hyperon-nucleon interactions to relatively higher energies up to $900\mathrm{MeV}/c$ for both the coupled-channel $\mathrm{\Lambda }p\to (\mathrm{\Lambda }p,{\mathrm{\Sigma }}^{+}n,{\mathrm{\Sigma }}^{0}p)$, ${\mathrm{\Sigma }}^{-}p\to (\mathrm{\Lambda }n,{\mathrm{\Sigma }}^{0}n,{\mathrm{\Sigma }}^{-}p)$ and single-channel ${\mathrm{\Sigma }}^{+}p\to {\mathrm{\Sigma }}^{+}p$ reactions. We show that although the leading order covariant chiral effective field theory is only constrained by the low energy data, it can describe the high energy data reasonably well, in particular, the J-PARC E40 differential cross sections. The predicted cusp structure close to the $\mathrm{\Sigma }N$ threshold in the $\mathrm{\Lambda }p\to \mathrm{\Lambda }p$ reaction agrees with the latest ALICE observation as well as with the results of the next-to-leading order heavy baryon chiral effective theory. On the other hand, the comparison with the latest CLAS data on the $\mathrm{\Lambda }p$ cross sections between 0.9 and 2.0 $\mathrm{GeV}/c$ clearly indicates the need for higher order chiral potentials for such high momenta. This is also the case for the latest J-PARC data on the $\mathrm{\Sigma }p\to \mathrm{\Lambda }n$ differential cross sections. Nevertheless, even for these cases, the predictions are in qualitative agreement with the data, albeit with large uncertainties, implying that the predicted total and differential cross sections are of relevance for ongoing and planned experiments.

The ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction plays a key role in accurately modeling and understanding the nucleosynthesis of the long-lived radioisotope ${}^{26}\mathrm{Al}$ observed throughout the galaxy by $\gamma$-ray telescopes via the detection of its 1.809 MeV $\gamma$-ray line. The ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction is responsible for redirecting the flux of nuclear material away from the ground state of the long-lived radioisotope ${}^{26}\mathrm{Al}$ (${}^{26}\mathrm{Al}^g$) in favor of its short-lived isomer (${}^{26}\mathrm{Al}^m$) which bypasses the emission of the 1.809 MeV $\gamma$ ray, but is observed in, for example, an excess of the isotopic abundance of ${}^{26}\mathrm{Mg}$ in meteorites. Uncertainties in the ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction rate are dominated by the nuclear properties of low-lying proton-unbound states in ${}^{26}\mathrm{Si}$. A high-sensitivity spectroscopic study of ${}^{26}\mathrm{Si}$ was performed at the John D. Fox Accelerator Laboratory at Florida State University, using a neutron/$\gamma$-ray coincidence measurement with the ${}^{24}\mathrm{Mg}({}^3\mathrm{He},n\gamma ){}^{26}\mathrm{Si}$ reaction. The present measurement solves previous discrepancies in the existence and location of the relevant resonances in ${}^{26}\mathrm{Si}$. Furthermore, the high sensitivity of the study allowed for a direct estimate of the 3${}_3^{+}\gamma$-partial width. The present experimental information combined with previous works provide an updated rate of the ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction at nova temperatures.

A compressible liquid-drop model (CLDM) is used to correlate uncertainties associated with the properties of the neutron star (NS) crust with theoretical estimates of the uncertainties associated with the equation of state (EOS) of homogeneous neutron and nuclear matter. For the latter, we employ recent calculations based on Hamiltonians constructed using chiral effective-field theory ($\chi \mathrm{EFT}$). Fits to experimental nuclear masses are employed to constrain the CLDM further, and we find that they disfavor some of the $\chi \mathrm{EFT}$ Hamiltonians. The CLDM allows us to study the complex interplay between bulk, surface, curvature, and Coulomb contributions, and their impact on the NS crust. It also reveals how the curvature energy alters the correlation between the surface energy and the bulk symmetry energy. Our analysis quantifies how the uncertainties associated with the EOS of homogeneous matter implies significant uncertainties for the composition of the crust, its proton fraction, and the volume fraction occupied by nuclei. We find that the finite-size effects impact the crust composition but have a negligible effect on the net isospin asymmetry of matter. The isospin asymmetry is largely determined by the bulk properties and the isospin dependence of the surface energy. The most significant uncertainties associated with matter properties in the densest regions of the crust, the precise location of the crust-core transition, are found to be strongly correlated with uncertainties associated with the Hamiltonians. By adopting a unified model to describe the crust and the core of NSs, we tighten the correlation between their global properties such as their mass-radius relationship, moment of inertia, crust thickness, and tidal deformability with uncertainties associated with the nuclear Hamiltonians.

We analyze the contribution of isovector and isoscalar proton-neutron pairing to the binding energies of even-even nuclei with $N-Z=0, 2, 4$ and atomic mass $20<A<100$. The binding energies are calculated in the mean-field approach by coupling a Skyrme-type functional to an isovector-isoscalar pairing force of zero range. The latter is treated in the framework of quartet condensation model (QCM), which conserves exactly the particle number and the isospin. The interdependence of pairing and deformation is taken into account by performing self-consistent Skyrme-HF $+$ QCM calculations in the intrinsic system. It is shown that the binding energies are not changing much when the isoscalar pairing is switched on. This fact is related to the off-diagonal matrix elements of the pairing force, which are less attractive for the isoscalar force, and to the competition between the isoscalar and isovector pairing channels.

The impact of nuclear dissipation on the dynamics of nuclear fission at low excitation energy is studied with a three-dimensional Langevin approach in which the two-center shell model is adopted to describe the nuclear shape and the single-particle potential. With three types of formulas for the friction tensor, such as the wall formula, the wall-and-window formula with and without the term related to the mass asymmetry change, the fragment mass and the total kinetic energy (TKE) distributions in low-energy fission are calculated. The calculated fragment mass distributions are almost identical for both with the wall formula and with the wall-and-window model without the term related to the mass asymmetry change, and both the results are consistent with the evaluated mass yields and the calculated results with the GEF model. Our study found that the term related to the mass asymmetry change in the window formula leads to an unreasonable shift of the peak position of the mass distribution. The TKE values calculated with the wall model are slightly larger than those with the wall-and-window model due to the more compact configuration obtained with the pure wall model. Moreover, the influences of the strength of friction tensor on the fragment distribution, the scission configuration, and the fission time distribution are investigated. With the present model the fission fragment mass distributions of U, Np, Pu, and Am isotopes are well reproduced and the systematic dependence of the averaged TKE on the Coulomb parameter is also well reproduced.

We compute the $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ global polarizations in semicentral heavy-ion collisions using the core-corona model where the source of $\mathrm{\Lambda }\mathrm{s}$ and $\overline{\mathrm{\Lambda }}\mathrm{s}$ is taken as consisting of a high-density core and a less dense corona. We show that the overall properties of the polarization excitation functions can be linked to the relative abundance of $\mathrm{\Lambda }\mathrm{s}$ coming from the core versus those coming from the corona. For low collision energies, the former are more abundant whereas for higher energies the latter become more abundant. The main consequence of this reversing of the relative abundance is that both polarizations peak at collision energies $\sqrt{s_{NN}}\lesssim 10$ GeV. The exact positions and heights of these peaks depend not only on this reversal of relative abundances, but also on the centrality class, which is directly related to the quark gluon plasma volume and lifetime, as well as on the relative abundances of $\mathrm{\Lambda }\mathrm{s}$ and $\overline{\mathrm{\Lambda }}\mathrm{s}$ in the core and corona regions. The intrinsic polarizations are computed from a field-theoretical approach that links the alignment of the strange quark spin with the thermal vorticity and modeling the quark gluon plasma volume and lifetime using a Bjorken expansion scenario. We predict that the $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ global polarizations should peak at the energy range accessible to NICA and HADES.

The $\mathrm{\Lambda }\mathrm{\Lambda }$ pairing effects in spherical and deformed multi-$\mathrm{\Lambda }$ hyperisotopes are investigated in the framework of the Skyrme-Hartree-Fock approach employing a $\delta$ pairing force with the pairing strength of $\mathrm{\Lambda }$ hyperons being $4/9$ of that for nucleons. For spherical hyperisotopes, the occurrences of magic numbers $-S=2$, 8, 18, 20, 34, 58, 68, and 70, which are attributed to a Woods-Saxon-like $\mathrm{\Lambda }$ hyperon potential, are evinced by the sudden drop of $2\mathrm{\Lambda }$ separation energies and the vanishing pairing gaps and pairing energies. The results are compared with equivalent ones in recent Hartree-Fock-Bogoliubov and relativistic-Hartree-Bogoliubov calculations. For the deformed hyperisotopes, more possible $\mathrm{\Lambda }$ hyperon magic numbers $-S=4$, 6, 10, 14, 26, 30, and 32 are found based on the analysis of the single-particle energy levels, and are all sensitive to the quadrupole deformation ${\beta }_2$. The steps of the $2\mathrm{\Lambda }$ separation energies are accordingly smaller than in spherical hyperisotopes, and the possibilities for pairing are consistently reduced.

With a view to applying the generator coordinate method to large configuration spaces, we propose a simple approximate formula to compute diabatic many-body matrix elements without having to evaluate two-body interaction matrix elements. The method is illustrated with two analytically solvable Hamiltonians based on the harmonic oscillator.

Ab initio nuclear many-body frameworks require extensive computational resources, especially when targeting heavier nuclei. Importance-truncation (IT) techniques allow one to significantly reduce the dimensionality of the problem by neglecting unimportant contributions to the solution of the many-body problem. In this work, we apply IT methods to the nonperturbative in-medium similarity renormalization group (IMSRG) approach and investigate the induced errors for ground-state energies in different mass regimes based on different nuclear Hamiltonians. We study various importance measures, which define the IT selection, and identify two measures that perform best, resulting in only small errors to the full IMSRG(2) calculations even for sizable compression ratios. The neglected contributions are accounted for in a perturbative way and serve as an estimate of the IT-induced error. Overall we find that the IT-IMSRG(2) performs well across all systems considered, while the largest compression ratios for a given error can be achieved when using soft Hamiltonians and for large single-particle bases.

We follow the idea that the QCD phase diagram may be described by a crossover from a hadron resonance gas to perturbative QCD using the switch function ansatz of Albright, Kapusta, and Young [Phys. Rev. C 90, 024915 (2014)]. While the switch function could be calibrated at vanishing baryon chemical potential with data from lattice QCD simulations, it has been suggested recently by Kapusta and Welle [Phys. Rev. C 104, L012801 (2021)] that in the zero temperature limit, the switch function parameter ${\mu }_0$ could be constrained by neutron star phenomenology, in particular by massive pulsars such as PSR $\text{J0740}+6620$ with a mass exceeding $2M_{\text{sun}}$. In this work we demonstrate that this procedure to constrain the QCD phase diagram does crucially depend on the fact that cold dense quark matter is very likely in a color superconducting state.

In this paper we study nuclear masses of proton-rich systems close to (both inside and outside) the proton drip line, in terms of mass relations for mirror nuclei. We show that mass relations of mirror nuclei are remarkably accurate for all nuclei (including very light nuclei) within the proton drip line, with root-mean-square deviations (RMSD) between 70–147 keV. A very simple formula is proposed to extend the mass relations to systems beyond the proton drip line, with the RMSD value of 183 keV (or 164 keV if the ${}^{11}\mathrm{O}-{}^{11}\mathrm{Li}$ mirror partners are excluded). Based on these mass relations, we predict 162 mass excesses of proton-rich systems (136 systems outside and 26 systems inside the proton drip line) close to the proton drip line, and tabulate these results in the Supplemental Material of this paper.

When a compound nucleus is formed at an excitation energy above the neutron-separation threshold, it is assumed that its de-excitation will proceed via neutron emission. However, if the excited nucleus is in a high-spin state, but does not have enough excitation energy to conserve angular momentum by either photon emission after neutron emission or relative angular momentum carried off by the neutron, the nucleus will de-excite via $\gamma$-emission instead. This effect, the spin inhibition, provides an insight into the structure of the compound nuclei and can aid the understanding of the distribution of the populated spin states in a compound nuclear reaction. In this work, the effects of spin inhibition on the $\gamma$-decay probabilities from states in ${}^{146,147}\mathrm{Sm}$ and ${}^{160}\mathrm{Dy}$ are presented. For high-spin states above the $S_n$, spin inhibition is able to suppress neutron emission, and de-excitation via $\gamma$-ray emission is observed for states up to 3 MeV above the $S_n$.

We investigate the low-lying positive-parity states in ${}^{12}\mathrm{Be}$, which are populated by the ${}^2\mathrm{H}({}^{13}\mathrm{B}$, ${}^3\mathrm{He})$ reaction via $l=1$ proton transfer for the first time using a radioactive beam ${}^{13}\mathrm{B}$ at 23 MeV/nucleon. Spectroscopic factors and excitation energies of these states are in reasonable agreement with the shell model predictions. Besides two bound states, we observe a resonant state at $E_x=4.8\pm 0.1\mathrm{MeV}$ with an intrinsic width of $0.42\pm 0.28$ MeV, which predominately decays via one neutron to the bound states in ${}^{11}\mathrm{Be}$. It most likely corresponds to the $E_n=1.24\mathrm{MeV}$ state observed in the previous one-proton removal reaction. The spin-parity of $2^{+}$ is tentatively assigned to this resonance according to the analysis of its angular distributions as well as the theoretical calculations, including shell model and Gamow coupled-channel approach.

Collective flow observables are known to be a sensitive tool to gain insights on the equation of state of nuclear matter from heavy-ion collision observations. Towards more quantitative constraints one has to carefully assess other influences on the collective behavior. In this work a hadronic transport approach smash (simulating many accelerated strongly interacting hadrons) is applied to study the first four anisotropic flow coefficients in $\text{Au}+\text{Au}$ collisions at $E_{\mathrm{lab}}=1.23A$ GeV in the context of the recently measured data by the HADES Collaboration. In particular, the formation of light nuclei is important in this energy regime. Two different approaches are contrasted to each other: A clustering algorithm inspired by coalescence as well as microscopic formation of deuterons via explicit cross sections. The sensitivity of directed and elliptic flow observables to the strength of the Skyrme mean field is explored. In addition, it is demonstrated that the rapidity-odd $v_3$ coefficient is practically zero in this energy regime and the ratio of $v_4/v_2^2$ is close to the value of 0.5 expected from hydrodynamic behavior. This study establishes the current understanding of collective behavior within the smash approach and lays the ground for future more quantitative constraints on the equation of state of nuclear matter within improved mean-field calculations.

A deep learning based method with the convolutional neural network (CNN) algorithm for determining the impact parameters is developed by using constrained molecular-dynamics model simulations, focusing on the heavy-ion collisions at the low-intermediate incident energies from several tens to one hundred MeV/nucleon in which the emissions of heavy fragments with the charge numbers larger than three become crucial. To make the CNN applicable in the task of the impact-parameter determination at the present energy range, specific improvements are made in the input selection, the CNN construction, and the CNN training. It is demonstrated from the comparisons of the deep CNN method and the conventional methods with the impact-parameter-sensitive observables that the deep CNN method shows better performance for determining the impact parameters, especially leading to the capability of providing better recognition of the central collision events. With a proper consideration of the experimental filter effect in both training and testing processes to keep consistency with the actual experiments, the good performance of the deep CNN method holds and performs significantly better in terms of predicting the impact parameters and recognizing the central collision events compared with conventional methods, demonstrating the superiority of the present deep CNN method. The deep CNN method with the consideration of the filter effect is applied in the deduction of nuclear stopping power. Higher accuracy for the stopping power deduction is achieved benefitting from the better impact-parameter determination using the deep CNN method, compared with using conventional methods. This result reveals the importance of selecting a reliable impact-parameter-determination method in the experimental deduction of the nuclear stopping power as well as other observables.

Atomic nuclei exhibit deformation, pairing correlations, and rotational symmetries. To meet these competing demands in a computationally tractable formalism, we revisit the use of general pair condensates with good particle number as a trial wave function for even-even nuclei. After minimizing the energy of the condensate, allowing for general triaxial deformations, we project out states with good angular momentum with a fast projection technique. To show applicability, we present example calculations from pair condensates in several model spaces and compare against angular-momentum projected Hartree-Fock and full configuration-interaction shell-model calculations. This approach successfully generates spherical, vibrational, and rotational spectra, demonstrating potential for modeling medium- to heavy-mass nuclei.

Background: The $Z=52$ nuclei ${}^{128}\mathrm{Te}$ and ${}^{130}\mathrm{Te}$ are interesting candidates to study nuclear-structure properties close to the $Z=50$ shell. The knowledge of lifetimes of low-lying states in those nuclei is still scarce.

Purpose: The goal of the present work is to extend the experimental database of nuclear level lifetimes of low-spin states in ${}^{128}\mathrm{Te}$ and ${}^{130}\mathrm{Te}$.

Methods: Nuclear level lifetimes were determined by means of the Doppler-shift attenuation method (DSAM) using $p-\gamma$ coincidences measured at the SONIC@HORUS setup located at the FN-Tandem ion accelerator of the University of Cologne.

Results: For ${}^{128}\mathrm{Te}$, lifetimes of eleven excited states could be determined, one of these for the first time. For the case of ${}^{130}\mathrm{Te}$, 18 nuclear level lifetimes were obtained, 15 for the first time. In both experiments, upper limits for lifetimes of several additional levels were determined. Moreover, the nuclear level scheme of ${}^{130}\mathrm{Te}$ could be extended. One additional level and 13 new transitions for levels above 2.7 MeV have been added. A standard shell-model calculation was performed and compared with the experimental results, showing an overall agreement.

Conclusions: DSAM using $p\text{−}\gamma$ coincidences is a powerful tool to determine lifetimes in the subpicosecond range free of feeding contributions. Although both experiments yielded low statistics, numerous lifetimes could be obtained. The use of $p\text{−}\gamma$ coincidences furthermore enables the extension of level schemes.

We study the effects of short- and long-range correlations on the charge radii of Ca isotopes. We start our investigation with an independent particle model consisting of Hartree-Fock plus Bardeen-Cooper-Schrieffer calculations with finite-range effective nucleon-nucleon interactions of Gogny type. The short-range correlation effects are evaluated by considering all the terms of a cluster expansion containing a single correlation line. The long-range correlations are taken into account by including the coupling with the quasiparticle random phase approximation phonons. While the effects of the short-range correlations are negligible, those of the long-range correlations largely modify the independent particle model results and improve the agreement with the experimental data.

Axial symmetry breaking in ${}^{144}\mathrm{Tm}$ is probed by examining its proton emission fine structure. The ground-state spin and parity in ${}^{144}\mathrm{Tm}$ and daughter ${}^{143}\mathrm{Er}$ are assigned unambiguously based on the corroboration of our calculations with the present data. We establish the first microscopic description of fine structure in odd-odd proton emitters, which is capable of resolving ambiguities present in the assignments of transitions in such nuclei.