Using an $e^{+}{e}^{-}$ collision data sample of $(10087\pm 44)\times {10}^6$ $J/\psi$ events taken at the center-of-mass energy of 3.097 GeV by the BESIII detector at the BEPCII collider, the process $\mathrm{\Lambda }+N\to {\mathrm{\Sigma }}^{+}+X$ is studied for the first time employing a novel method. The ${\mathrm{\Sigma }}^{+}$ hyperons are produced by the collisions of $\mathrm{\Lambda }$ hyperons from $J/\psi$ decays with nuclei in the material of the BESIII detector. The total cross section of $\mathrm{\Lambda }+{}^9\mathrm{Be}\to {\mathrm{\Sigma }}^{+}+X$ is measured to be $\sigma =(37.3\pm 4.7\pm 3.5)$ mb with $\mathrm{\Lambda }$ momenta within $[1.057,1.091]$ GeV/$c$, where the uncertainties are statistical and systematic, respectively. This analysis is the first study of $\mathrm{\Lambda }$-nucleon interactions at an $e^{+}{e}^{-}$ collider, providing information and constraints relevant for the strong-interaction potential, the origin of color confinement, the unified model for baryon-baryon interactions, and the internal structure of neutron stars.

Numerical differentiation is crucial for extracting reliable nucleon momentum distributions (NMDs) from cross section data of inclusive electron scattering within the framework of $y$ scaling. A naive application of the traditional finite difference approach to noisy experimental data may lead to negative values and suspect fluctuations in NMDs at high momenta. To solve this problem, we propose using a sophisticated modern technique known as smoothing spline for numerical differentiation, which has a number of advantages over the traditional approach and gives NMDs more compatible with physical considerations. We extract new NMDs for the deuteron and study their scaling behaviors with respect to the nucleon momentum $k$. It is found that NMDs may follow piecewise scaling laws with $n\left(k\right)\sim 1/k^5$ for $0.25<k<0.6 \text{GeV}/\mathrm{c}$ and $n\left(k\right)\sim 1/k^7$ for $0.6<k<1.2 \text{GeV}/\mathrm{c}$.

This study employs the dinuclear system model (DNS-sysu) to investigate drift and fluctuation mechanisms in ${}^{136}\mathrm{Xe}+{}^{209}\mathrm{Bi}$ collisions above the Coulomb barrier. The DNS-sysu model demonstrated its effectiveness in providing reasonable descriptions of drift and fluctuation dynamics for the multinucleon transfer reaction at low energies. We investigate temperature-induced changes in the shell effect, which impacts nucleon transfer. At higher energies, the weakening constraint of the potential energy surface leads to a reversal in evolution direction. Additionally, the consideration of shell corrections notably affects fragment distribution at low energies but diminishes for high-energy conditions. This research provides valuable insights into understanding the macroscopic manifestation of nucleon transfer in the multinucleon transfer reaction.

We present a simple semiclassical treatment of photon cascades, suitable for use in nuclear fission simulation codes. The approximation is here developed for $E1$ and $E2$ transitions and its quality is illustrated for a variety of two-photon cascades. Implementation of the treatment into Monte Carlo simulations would make it possible to address photon correlation observables quantitatively.

We perform a calculation of dense and hot nuclear matter where the mean interaction between nucleons is described by in-medium effective fields and where we employ analytical approximations of the Fermi integrals. We generalize a previous work [Dutra et al., Astrophys. J. 952, 5 (2023)] where we have addressed the case of the Fermi gas model with in-medium effective mass. In the present work we fully treat the in-medium interaction by considering both its contribution to the in-medium effective fields, which can be subsumed by the mass in some cases, and to the potential term. Our formalism is general and could be applied to relativistic and nonrelativistic approaches. It is illustrated for different popular models—Skyrme, nonlinear, and density-dependent relativistic mean-field models—but also for the metamodel, and it provides a clear understanding of the in-medium correction to the pressure, which is present in the case of the Skyrme and metamodel but is not for the relativistic ones. For the Fermi integrals, we compare the analytical approximation to the so-called “exact” numerical calculations in order to quantitatively estimate the accuracy of the approximation.

High-spin states in ${}^{112}\mathrm{Sn}$ were investigated using the ${}^{103}\mathrm{Rh}({}^{12}\mathrm{C}, 1p2n$) reaction at a beam energy of 62 MeV. Six electric dipole $E1$ transitions linking positive- and negative-parity intruder bands have been identified in ${}_{50}{}^{112}\mathrm{Sn}$ through $\gamma$-ray spectroscopy. The experimental reduced $E1$ transition probabilities $B\left(E1\right)$, derived from level lifetimes by means of the Doppler-shift attenuation method, are of the order of ${10}^{-4}$ W.u., which gives evidence for the octupole correlation in ${}^{112}\mathrm{Sn}$. The systematics of the reduced $E1$ transition probabilities and neutron energy levels of $5/2^{+}$ and $11/2^{-}$ in Xe isotopes suggest an enhanced octupole correlation at neutron number $N=62$, which is supported by the relativistic Hartree-Bogoliubov calculations.

We present an improved version of the Wong formula for heavy-ion fusion, where the parameters of the parabolic approximation of the Coulomb barrier are replaced by parameters of the $l$-dependent potential at an effective partial wave. A pocket formula for this $l$ dependence is given. This version reproduces the fusion cross sections of quantum-mechanical calculations very well, even when the original Wong formula is invalid. The same procedure is used to derive an improved expression for the classical fusion cross section, which is very accurate at above-barrier energies. Based on this classical expression, we propose a new method to reduce fusion data in this energy range. This method is used to perform a comparative study of complete fusion suppression in collisions of weakly bound projectiles. This study indicates that the suppression of complete fusion is essentially due to the action of nuclear breakup couplings.

Nuclide production cross sections are crucial in nuclear research, development, space exploration, and astrophysical investigations. Despite their importance, limited experimental data availability restricts the practicality of phenomenological approaches to comprehensive cross-section estimation. To address this, we propose a Gaussian process-based machine learning (ML) model capable of transferring knowledge from elements with abundant data to those with limited or no experimental data. Our ML model not only enables comprehensive cross-section estimations for various elements but also demonstrates predictive capabilities akin to physics models, even in regions with scarce training data.

Within the framework of the dinuclear system (DNS) model, this study delves into the impact of various nuclear mass models on evaluating the fusion probability of superheavy nuclei. Nuclear mass models, as crucial inputs to the DNS model, exhibit slight variations in binding energy, quadrupole deformation, and extrapolation ability; these subtle differences can significantly influence the model's outcomes. Specifically, the study finds that nuclear mass plays a pivotal role in determining fusion probability and Q-value. By numerically solving a set of master equations, the study examines how binding energies from different mass models affect the fusion probability of colliding nuclei, taking the example of ${}^{48}\mathrm{Ca}+{}^{243}\mathrm{Am}\to {}^{291}\mathrm{Mc}$. A careful analysis of the potential energy surface reveals that the inner fusion barriers lead to variations in fusion probabilities. Importantly, the study demonstrates that the synthesis cross sections of superheavy nuclei calculated using different nuclear mass models align well with experimental data, falling within an error range of one order of magnitude. This finding underscores the reliability of our model predictions. Looking ahead, the study utilizes five distinct nuclear mass models to predict the synthesis cross sections of superheavy elements 119 and 120, along with their associated uncertainties. These predictions offer valuable insights into the feasibility of synthesizing these elusive elements and pave the way for future experimental explorations.

Two-dimensional (2D) jet tomography is a promising tool to study jet medium modification in high-energy heavy-ion collisions. It combines gradient (transverse) and longitudinal jet tomography for selection of events with localized initial jet production positions. It exploits the transverse asymmetry and energy loss that depend, respectively, on the transverse gradient and jet path length inside the quark-gluon plasma (QGP). In this study, we employ 2D jet tomography to study medium modification of the jet shape of $\gamma$-triggered jets within the linear Boltzmann transport (LBT) model for jet propagation in heavy-ion collisions. Our results show that jets with small transverse asymmetry ($A_N^{\vec{n}}$) or small $\gamma$-jet asymmetry ($x_{J\gamma }=p_T^{\mathrm{jet}}/p_T^{\gamma }$) exhibit a broader jet shape than those with larger $A_N^{\vec{n}}$ or $x_{J\gamma }$, since the former are produced at the center and go through longer path lengths while the later are off center and close to the surface of the QGP fireball. In events with finite values of $A_N^{\vec{n}}$, jet shapes are asymmetric with respect to the event plane. Hard partons at the core of the jet are deflected away from the denser region while soft partons from the medium response at large angles flow toward the denser part of QGP. Future experimental measurements of these asymmetric features of the jet shape can be used to study the transport properties of jets and medium responses.

The $\varphi$ meson and $\mathrm{\Omega }$ baryon provide unique probes of the properties of the quark-gluon plasma (QGP) at hadronization in relativistic heavy-ion collisions. Using the quark recombination model with the quark phase-space information parameterized in a viscous blast wave, we perform Bayesian inference of the shear and bulk viscosities of the QGP at hadronization with a temperature of $T\approx 160$ MeV by analyzing the $\varphi$ and $\mathrm{\Omega }$ data in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=19.6–200$ GeV and $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV, corresponding to a baryon chemical potential variation from ${\mu }_B\approx 0$ (at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV) to 200 MeV (at $\sqrt{s_{\mathrm{NN}}}=19.6$ GeV). We find that the shear viscosity to enthalpy ratio $\eta T/(\epsilon +P)$ of the QGP at hadronization decreases as ${\mu }_B$ increases, with $\eta T/(\epsilon +P)\approx 0.18$ at ${\mu }_B=0$ and $\eta T/(\epsilon +P)\approx 0.08$ at ${\mu }_B=200$ MeV, while the corresponding specific bulk viscosity is essentially constant with $\zeta T/(\epsilon +P)=0.02–0.04$ for ${\mu }_B<200$ MeV. Our results suggest that the QGP at hadronization ($T\approx 160$ MeV) with finite baryon density is more close to perfect fluid than that with zero baryon density.

The isomeric structure and properties in proton-rich nuclides are crucial for determining the path of the rapid proton capture process ($rp$-process). For example, bound nuclei inside the dripline can have unbound isomeric states and change the $rp$-process pathway. The configuration interaction shell model is used to investigate nuclei around the $Z=N$ line at the southwest region of ${}^{100}\mathrm{Sn}$. The excitation mechanism of $1/2_1^{-}$ isomers is identified as dominated by exciting one nucleon in the $1p_{1/2}$ orbit to the $0g_{9/2}$ orbit. The study explores the decay properties of both the ground and isomeric states. Remarkably, competitive ${\beta }^{+}$ decay and proton emission are predicted in the unbound $1/2_1^{-}$ isomer of ${}^{97}\mathrm{Sn}$, suggesting potential influences on the $rp$-process pathway.

Background: Cluster states in ${}^{13}\mathrm{N}$ are extremely difficult to measure due to the unavailability of ${}^9\mathrm{B}+\alpha$ elastic-scattering data.

Purpose: Using $\beta$-delayed charged-particle spectroscopy of ${}^{13}\mathrm{O}$, clustered states in ${}^{13}\mathrm{N}$ can be populated and measured in the $3\alpha +p$ decay channel.

Methods: One-at-a-time implantation and decay of ${}^{13}\mathrm{O}$ was performed with the Texas Active Target Time Projection Chamber. $149\beta 3\alpha p$ decay events were observed and the excitation function in ${}^{13}\mathrm{N}$ reconstructed.

Results: Four previously unknown $\alpha$-decaying excited states were observed in ${}^{13}\mathrm{N}$ at an excitation energy of 11.3, 12.4, 13.1, and 13.7 MeV decaying via the $3\alpha +p$ channel.

Conclusions: These states are seen to have a ${[}^9\mathrm{B}(\mathrm{g}.\mathrm{s})⨂\alpha /p+{}^{12}\mathrm{C}\left(0_2^{+}\right)], {[}^9\mathrm{B}\left({\frac{1}{2}}^{+}\right)⨂\alpha ], {[}^9\mathrm{B}\left({\frac{5}{2}}^{+}\right)⨂\alpha ]$, and ${[}^9\mathrm{B}\left({\frac{5}{2}}^{+}\right)⨂\alpha ]$ structure, respectively. A previously seen state at 11.8 MeV was also determined to have a $[p+{}^{12}\mathrm{C}(\mathrm{g}.\mathrm{s}.)/p+{}^{12}\mathrm{C}\left(0_2^{+}\right)]$ structure. The overall magnitude of the clustering is not able to be extracted, however, due to the lack of a total width measurement. Clustered states in ${}^{13}\mathrm{N}$ (with unknown magnitude) seem to persist from the addition of a proton to the highly $\alpha$-clustered ${}^{12}\mathrm{C}$. Evidence of the ${\frac{1}{2}}^{+}$ state in ${}^9\mathrm{B}$ was also seen to be populated by decays from ${}^{13}\mathrm{N}^{★}$.

Excited states of ${}^{207}\mathrm{Rn}$ have been investigated with the ${}^{197}\mathrm{Au}({}^{14}\mathrm{N}, 4n){}^{207}\mathrm{Rn}$ reaction at a beam energies of 78 MeV. The level scheme of ${}^{207}\mathrm{Rn}$ was revised and expanded considerably by the $\gamma$ -$\gamma$ coincidence measurement. A large-scale shell-model calculation was performed for the purpose of improving the understanding of some levels of ${}^{207}\mathrm{Rn}$. A rotational-like band has been observed in ${}^{207}\mathrm{Rn}$ and the microscopic three-dimensional tilted axis cranking covariant density functional theory (3DTAC-CDFT) was applied to explain it. The calculated results indicate the weak oblate deformation and emergence of principal axis rotation for ${}^{207}\mathrm{Rn}$. This band is suggested to be a collective oblate band.

We investigate $\alpha$-decay half-lives for 74 $\le$ Z $\le$ 92 even-even nuclei within the semiclassical WKB approximation in deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). The $\alpha$-particle preformation factors are estimated from cluster-formation model using both empirical AME2020 binding energies and numerical ones obtained by a deep neural network (DNN) study in which the available DRHBc binding energies are used as training set. We find that our estimated $\alpha$-decay half-lives are qualitatively in agreement with experimental results. We also compare our results with the empirical formulas, ZZCW and UNIV. Based on these observation, we extend our predictions of $\alpha$-decay half-lives for the isotopes whose experimental data are not available.

The $\gamma$-ray strength functions (GSFs) and nuclear level densities (NLDs) below the neutron threshold have been extracted for ${}^{111–113,116–122,124}\mathrm{Sn}$ from particle-$\gamma$ coincidence data with the Oslo method. The evolution of bulk properties of the low-lying electric dipole response has been investigated on the basis of the Oslo GSF data and results of a recent systematic study of electric- and magnetic dipole strengths in even-even Sn isotopes with relativistic Coulomb excitation. The obtained GSFs reveal a resonance-like peak on top of the tail of the isovector giant dipole resonance centered at $\approx 8$ MeV and exhausting $\approx 2\%$ of the classical Thomas-Reiche-Kuhn (TRK) sum. For mass numbers $\ge 118$ the data suggest also a second peak centered at $\approx 6.5$ MeV. It corresponds to 0.1%–0.5% of the TRK sum rule and shows an approximate linear increase with the mass number. In contrast with predictions of the relativistic quasiparticle random-phase and time-blocking approximation calculations, no monotonic increase in the total low-lying $E1$ strength was observed in the experimental data from ${}^{111}\mathrm{Sn}$ to ${}^{124}\mathrm{Sn}$, demonstrating rather similar strength distributions in these nuclei. The Oslo GSFs and NLDs were further used as inputs to constrain the cross sections and Maxwellian-averaged cross sections of $(n,\gamma )$ reactions in the Sn isotopic chain using talys. The obtained results agree well with other available experimental data and the recommended values from the JINA REACLIB, BRUSLIB, and KADoNiS libraries. Despite relatively small exhausted fractions of the TRK sum rule, the low-lying electric dipole strength makes a noticeable impact on the radiative neutron-capture cross sections in stable Sn isotopes. Moreover, the experimental Oslo inputs for the ${}^{121,123}\mathrm{Sn}(n,\gamma ){}^{122,124}\mathrm{Sn}$ reactions were found to affect the production of Sb in the astrophysical $i$ process, providing new constraints on the uncertainties of the resulting chemical abundances from multizone low-metallicity asymptotic giant branch stellar models.

The high spin level structures of ${}^{100}\mathrm{Ru}$ have been studied through discrete-line $\gamma$-ray spectroscopy. This study reveals the existence of seven interleaved $E1$ transitions between two alternate parity bands of ${}^{100}\mathrm{Ru}$, which is a novel observation for this mass region. The measured values of the $B\left(E1\right)/B\left(E2\right)$ rates exhibit an enhancement and the energy splitting between the alternate parity bands vanishes beyond $I=16\hslash$. Similar observations for $N=88$ isotones have been proposed to be an indicator of a phase transition from octupole vibration to octupole deformation. Thus, the present data seem to indicate the presence of octupole deformation in ${}^{100}\mathrm{Ru}$ beyond $I=16\hslash$.

Background: Since 1919, when Rutherford measured the first nuclear reaction, and 1954, when Feshbach et al. [Phys. Rev. 96, 448 (1954)] proposed the optical model (OM), as the simplest mathematical approach for describing nuclear reactions, a general description for stable, tightly and weakly bound, and exotic nuclei reactions is still missing. The Feshbach OM presents two advantages: (i) it converts a complicated problem of many bodies (nucleons) into a problem of two bodies (nuclei) through an average potential of interaction, and (ii) it proposes a complex (real and imaginary) mathematical description for the so-called optical potential (OP).

Purpose: We propose to study the OP (real and imaginary) strengths and their energy dependence, in reactions involving stable, tightly and weakly bound, and exotic nuclei projectiles on a ${}^{64}\mathrm{Zn}$ target, at energies around the respective Coulomb barriers. We also propose to compare the current results to previous ones obtained for the same projectiles reacting on the heavier ${}^{120}\mathrm{Sn}$ target.

Method: We analyze experimental elastic scattering angular distributions of ${}^{4,6}\mathrm{He}, {}^{6,7}\mathrm{Li}, {}^{9,10,11}\mathrm{Be}$, and ${}^8\mathrm{B}$ impinging on the same (${}^{64}\mathrm{Zn}$) target, at bombarding energies around the respective Coulomb barriers. Within the data set, we report on OM calculations and the determined OP, with the respective uncertainties quantification, based on the double-folding (DF) São Paulo potential (SPP).

Results: Within the SPP approach, we compare the sensitivity of the OM theoretical predictions to different models assumed for the nuclear matter densities and to variations in the OP form factor and strengths. The best-fit parameters from OP study correlate with projectile breakup process, at scattering energies around the Coulomb barrier. Thus, we propose optimum energies for which the projectile breakup yield could be favored, as a function of the projectile breakup $Q$ value and the Coulomb barrier of the system. The results are shown to be systematical, when analyzing different weakly bound nuclei projectiles impinging on targets with different masses (and atomic numbers). As a test of consistency, we apply the method to another specific case: ${}^7\mathrm{Li}+{}^{80}\mathrm{Se}$.

Conclusion: The results represent important advances toward a fundamental mathematical description mainly for weakly bound nuclei reactions. The capability of predicting optimum projectile breakup yields, as a function of energy, represents an important tool for planning new experiments on weakly bound nuclei reactions. The determined OP must be of value for application to further calculations on such nuclei reactions, at energies around the Coulomb barrier, besides studying the OP dependence with energy.

In this paper, we critically examine hierarchies between the energy scales that determine quarkonium dynamics in the quark gluon plasma. A particularly important role is played by the ratio of the binding energy of species ($E_b$) and the medium scales; temperature ($T$) and Debye mass ($m_D$). It is well known that if these ratios are much larger than 1 then the dominant process governing quarkonium evolution is dissociation by thermal gluons (gluodissociation). On the other hand, if the ratio $E_b/T$ is much smaller than one then quarkonium dynamics is dominated by screening and Landau damping of the exchanged gluons. Here we show that over most of the evolution, the scale hierarchies do not fall in either limit and one needs to use the full structure of the gluonic spectral function to follow the dynamics of the $Q\overline{Q}$ pair. This has a significant bearing when we follow the quantum dynamics of quarkonia in the medium. The inverse medium relaxation time is also $\approx T$ and if $E_b$ is comparable (or larger) in magnitude to $T$, the quantum evolution of $Q\overline{Q}$ is nonlocal in time within the Brownian approximation.