Within the framework of an extended quantum molecular dynamics model, we simulated ${}^{40}\mathrm{Ca}+{}^{16}\mathrm{O}$ collisions at beam energies ranging from 60 to 150 MeV/nucleon for ${}^{16}\mathrm{O}$ with different $\alpha$-cluster configurations. Results imply that different $\alpha$-cluster configurations lead to different yields of deuteron, triton, ${}^3\mathrm{He}$, and ${}^4\mathrm{He}$, but not for proton and neutron. We discuss the effect of geometric fluctuations which are presented by double ratios of light nuclei, namely ${\mathcal{O}}_{\text{p-d-t}}$ and ${\mathcal{O}}_{\text{p-d-He}}$. It is found that the magnitude hierarchy of geometric fluctuations is chain, kite, square, and tetrahedron structures of ${}^{16}\mathrm{O}$. ${\mathcal{O}}_{\text{p-d-t}}$ has maximum value around 80–100 MeV/nucleon, which could be related to liquid-gas phase transition, that is consistent with results from the charge distribution of the heaviest fragments in the collisions.

The ${}^{232}\mathrm{Th}+{}^{48}\mathrm{Ca}$ reaction has been studied at the gas-filled separator DGFRS-2 online to the cyclotron DC280 at the SHE Factory at JINR. Three new nuclides were synthesized for the first time: a spontaneously fissioning (SF) ${}^{268}\mathrm{Sg}$ with the half-life $T_{\mathrm{SF}}=13\begin{array}{c}+17\\ -4\end{array}$ s; an α decaying ${}^{272}\mathrm{Hs}$ with $T_{\alpha }=0.16\begin{array}{c}+0.19\\ -0.06\end{array}$ s and $E_{\alpha }=9.63\pm 0.02\mathrm{MeV}$; and ${}^{276}\mathrm{Ds}$ with $T_{1/2}=0.15\begin{array}{c}+0.10\\ -0.04\end{array}$ ms, $E_{\alpha }=10.75\pm 0.03\mathrm{MeV}$, and an SF branch of 57%. The decay properties of these nuclei are in agreement with the systematics of experimental partial half-lives and α-decay energies of heavy known nuclei, as well as spontaneous-fission half-lives. The cross sections of the $4n$-evaporation channel of $0.07\begin{array}{c}+0.17\\ -0.06\end{array}$ pb, $0.7\begin{array}{c}+1.1\\ -0.5\end{array}$ pb, and $0.11\begin{array}{c}+0.46\\ -0.09\end{array}$ pb were measured at 231, 238, and 251 MeV, respectively.

Neutron-rich Nd and Sm isotopes are known to exhibit shape phase transition as a function of neutron number. Among them, ${}^{150}\mathrm{Nd}$ and ${}^{150}\mathrm{Sm}$ are important not only because they are transitional nuclei but also because they are the parent and daughter nuclei of double-$\beta$ decay. We performed large-scale shell-model calculations of even-even Nd and Sm isotopes, including the spherical-deformed shape transition. The quasiparticle vacua shell model enables us to perform shell-model calculations with sufficiently large model space with the ${}^{110}\mathrm{Zr}$ inert core. The shell-model result well reproduces the experimental excitation energies and quadrupole properties of the yrast and nonyrast states. The nuclear matrix element of neutrinoless double-$\beta$ decay of ${}^{150}\mathrm{Nd}$ is evaluated showing its modest enhancement by shape mixing.

In the present work, we systematically study the spectroscopic factor of proton radioactivity $\left(S_p\right)$ with $A>100$ using the deformed two-potential approach (D-TPA). It is found that there is a link between the quadrupole deformation parameter of proton emitter and $S_p$. Based on this result, we propose a simple analytic formula for estimating the spectroscopic factor of proton radioactivity. With the help of this formula, the calculated half-lives of proton radioactivity can reproduce the experimental data successfully within a factor of 2.77. Furthermore, we extend the D-TPA with this formula for evaluating the spectroscopic factor to predict the proton radioactivity half-lives of 12 proton radioactivity candidates whose radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020. For comparison, the universal decay law for proton radioactivity (UDLP) and the new Geiger-Nuttall law (NG-N) are also used. It turns out that all of the predicted results are basically consistent with each other.

Nuclear systems, ranging from atomic nuclei to dense matter probed in neutron stars, are governed by strong interactions. Three-nucleon forces have been found to be a crucial ingredient for the reliable description of these systems. Here, we explore how astrophysical data on neutron stars and their mergers from current and next-generation observatories will enable us to distinguish nuclear Hamiltonians. In particular, we investigate two different nuclear Hamiltonians that have been adjusted to reproduce two-nucleon scattering data and properties of light nuclei, but differ in the three-nucleon interactions among neutrons. We find that no significant constraints can be obtained from current data, but that the proposed Einstein Telescope could provide strong evidence to distinguish among these Hamiltonians.

Jet measurements in heavy ion collisions can provide constraints on the properties of the quark gluon plasma, but the kinematic reach is limited by a large, fluctuating background. We present a novel application of symbolic regression to extract a functional representation of a deep neural network trained to subtract background from jets in heavy ion collisions. We show that the deep neural network is approximately the same as a method using the particle multiplicity in a jet. This demonstrates that interpretable machine learning methods can provide insight into underlying physical processes.

With their complex low-spin structure, the germanium isotopes have accrued a large number of experimental data which challenge nuclear models. The structure of the ${}^{74}\mathrm{Ge}$ isotope is investigated here with nuclear resonance fluorescence as part of an extensive campaign of experimental tests of the shell model in the germanium isotopic chain using a number of complementary techniques. Levels were excited with $3.10–5.44$ MeV photon beams provided by the High Intensity Gamma-Ray Source at TUNL. Many new levels were identified and their spins, parities, branching ratios, and associated scattering cross section values were determined. Large-scale shell-model calculations, which include jj44b and JUN45 effective interactions developed to describe nuclei in this mass region, predict the new data satisfactorily. This study extends the validation of these two interactions, which are candidates for computation of matrix elements to be used in the interpretation of neutrinoless double-$\beta$ decay experiments in ${}^{76}\mathrm{Ge}$, into the low-spin, high excitation energy domain.

Bulk properties, spectrum, and nuclear response of ${}^8\mathrm{He}$ are investigated within the equation of motion phonon method, which generates an orthonormal basis of $n$-phonon states ($n=0,1,2,3...$) whose constituents are Tamm-Dancoff phonons. The basis is free of any contamination induced by the center-of-mass motion, in virtue of a procedure exploiting the singular value decomposition of rectangular matrices. A self-consistent calculation is performed within a space spanned by a basis of $n$-phonon states up to $n=3$ using a potential derived from the chiral effective field theory. The Hartree-Fock single-particle states are obtained from a harmonic-oscillator space including all major shells up to $N_{max}=12$. The calculation is exact up to $n=2$, whereas the three-phonon ($n=3$) states are assumed to be composed of noninteracting $n=1$ and $n=2$ constituent phonons. It yields bulk and spectroscopic observables consistent with the available experimental data and provides an electric dipole response exhibiting distinctive signatures.

Using the recent model-independent determination of the charge-weak form factor difference $\mathrm{\Delta }{F}_{\mathrm{CW}}$ in ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ by the CREX and PREX-2 collaborations together with some well-determined properties of doubly magic nuclei, we perform Bayesian inference of the symmetry energy $E_{\mathrm{sym}}\left(\rho \right)$ and the neutron skin thickness $\mathrm{\Delta }{r}_{\mathrm{np}}$ of ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ within the Skyrme energy density functional (EDF). We find the inferred $E_{\mathrm{sym}}\left(\rho \right)$ and $\mathrm{\Delta }{r}_{\mathrm{np}}$ separately from CREX and PREX-2 are compatible with each other at $90\%$ C.L., although they are inconsistent at $68.3\%$ C.L. with CREX (PREX-2) favoring a very soft (stiff) $E_{\mathrm{sym}}\left(\rho \right)$ and rather small (large) $\mathrm{\Delta }{r}_{\mathrm{np}}$. By combining the CREX and PREX-2 data, we obtain a soft symmetry energy around saturation density ${\rho }_0$ and thinner $\mathrm{\Delta }{r}_{\mathrm{np}}$ of ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$, which are found to be closer to the corresponding results from CREX alone, implying the PREX-2 is less effective to constrain the $E_{\mathrm{sym}}\left(\rho \right)$ and $\mathrm{\Delta }{r}_{\mathrm{np}}$ due to its lower precision of $\mathrm{\Delta }{F}_{\mathrm{CW}}$. Furthermore, we find the Skyrme EDF results inferred by combining the CREX and PREX-2 data nicely agree with the measured dipole polarizabilities ${\alpha }_D$ in ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ as well as the neutron matter equation of state from microscopic calculations. The implications of the inferred soft $E_{\mathrm{sym}}\left(\rho \right)$ around ${\rho }_0$ are discussed.

We report the measurement of fusion-evaporation residues emerging from ${}^6\mathrm{Li}+\mathrm{Zn}$ reaction within the 21–43 MeV energy range in conjunction with the underlying reaction dynamics in the scarcely explored light-medium mass region. The stack foil activation technique followed by offline $\gamma$ spectroscopy was employed to measure the cross sections of residues populated in the reaction. The measured data were compared with theoretical predictions from statistical model codes like pace4 and empire3.2.2 to probe the underlying reaction dynamics. The imitation of $n$- and $p$-channel data grossly by both the model codes suggests the production of residues via the complete fusion (CF) mode, while the enhancement observation in $\alpha$-channel cross sections hints at the signatures of breakup fusion in addition to the dominant CF. We report a new branching intensity of 93.31 keV $\gamma$-line retrieved experimentally from ${}^{67}\mathrm{Ga}$ decay following the end of bombardment activity in each target foil. The optimized production of ${}^{67}\mathrm{Ga}$ is also reported from the application perspective.

The yield distributions of neutron-induced fission of actinides were calculated and evaluated by using the improved scission-point model with considering octupole deformation of fragments. We studied the influence of the octupole deformation on the asymmetric yields of actinides fission. The more probable scission configuration is the pear-shaped heavy fragments rather than more spherical shape. We used the improved scission model to calculate the peak of charge and neutron distributions and compared results with the experimental data. The results confirm that the main asymmetric fission mode of the heavy actinides fission is indeed characterized by “${\mathrm{Z}}_{\mathrm{H}}\approx 54$.” The protons configuration of heavy fragment plays a dominant role in asymmetric fission of actinides.

Models of the $\beta$-delayed neutron emission ($\beta n$) assume that neutrons are emitted statistically via an intermediate compound nucleus post $\beta$ decay. Evidence to the contrary was found in an ${}^{134}\mathrm{In}\beta$-decay experiment carried out at ISOLDE CERN. Neutron emission probabilities from the unbound states in ${}^{134}\mathrm{Sn}$ to known low-lying, single-particle states in ${}^{133}\mathrm{Sn}$ were measured. The neutron energies were determined using the time-of-flight technique, and the subsequent decay of excited states in ${}^{133}\mathrm{Sn}$ was studied using $\gamma$-ray detectors. Individual $\beta n$ probabilities were determined by correlating the relative intensities and energies of neutrons and $\gamma$ rays. The experimental data disagree with the predictions of representative statistical models which are based upon the compound nucleus postulate. Our results suggest that violation of the compound nucleus assumption may occur in $\beta$-delayed neutron emission. This impacts the neutron-emission probabilities and other properties of nuclei participating in the $r$-process. A model of neutron emission, which links the observed neutron emission probabilities to nuclear shell effects, is proposed.

Results from the study of the ${\beta }^{-}$ decay of ${}^{45}\mathrm{Cl}$, produced in the fragmentation of a 140-MeV/u ${}^{48}\mathrm{Ca}$ beam, are presented. The half-life for ${}^{45}\mathrm{Cl}\beta$ decay is measured to be 513(36) ms. The ${\beta }^{-}$ and ${\beta }^{-}1n$ decay of ${}^{45}\mathrm{Cl}$ populated excited states in ${}^{45,44}\mathrm{Ar}$, respectively. On the basis of $\gamma$-ray singles and $\gamma \text{−}\gamma$ coincidence data, decay schemes for the two daughter nuclei have been established. They are compared with shell model calculations using the FSU interaction. The low-lying negative parity states for ${}^{45}\mathrm{Ar}$ are well described by a single particle (neutron) occupying orbitals near the Fermi surface, whereas neutron excitations across the $N=20$ shell gap are needed to explain the positive-parity states which are expected to be populated in allowed Gamow-Teller $\beta$ decay of ${}^{45}\mathrm{Cl}$. The highest $\beta$ feeding to the $5/2^{+}$ state in ${}^{45}\mathrm{Ar}$ from the ground state of ${}^{45}\mathrm{Cl}$ points towards a $3/2^{+}$ spin-parity assignment of the ground state of the parent over the other possibility of $1/2^{+}$. The high $Q_{{\beta }^{-}}$ value of ${}^{45}\mathrm{Cl}$ decay allows for the population of $1p1h$ states above the neutron separation energy in ${}^{45}\mathrm{Ar}$ leading to positive parity states of ${}^{44}\mathrm{Ar}$ being populated by removal of one neutron from the $sd$ shell. The spin-parities of the excited levels in ${}^{44}\mathrm{Ar}$ are tentatively assigned for the first time by comparison with the shell model calculations. The 2978 keV level of ${}^{44}\mathrm{Ar}$ is identified as the excited $0^{+}$ level which could correspond to a different configuration from the ground state.

Background: Quantum simulations offer the potential to predict the structure and dynamics of nuclear many-body systems that are beyond the capabilities of classical computing. Generally, preparing the ground state of strongly interacting many-body systems relevant to nuclear physics is, however, inefficient, even using ideal quantum computers. In addition, currently available noisy intermediate-scale quantum (NISQ) era quantum devices possess modest numbers of qubits, limiting the size of quantum many-body systems that can be simulated. In this context, a reformulation of the quantum many-body problems using truncated model spaces and Hamiltonians is desirable to make them more amenable to near-term quantum computers. The importance of symmetries in low-energy theories, including effective field theories (EFTs), lattice quantum chromodynamics (QCD), and effective model spaces for nuclear systems, in particular their interplay with the reduction of active Hilbert spaces, is well known. Lesser known is the fact that the noncommutivity of some symmetries and truncations of the model space can be profitably combined with variational calculations to rearrange the entanglement into localized structures and enable more efficient simulations.

Purpose: The goal of the present study is to explore and utilize the noncommutivity of symmetries and model-space truncations of quantum many-body systems important to nuclear physics, particularly in combination with variational algorithms for quantum simulations and effective Hamiltonian learning.

Method: We introduce an iterative hybrid classical-quantum algorithm, the Hamiltonian learning variational quantum eigensolver (HL-VQE), that simultaneously optimizes an effective Hamiltonian, thereby rearranging entanglement into the effective model space, and the associated ground-state wave function. Quantum simulations, using classical computers and IBM's superconducting-qubit quantum computers, are performed to demonstrate the HL-VQE algorithm, in the context of the Lipkin-Meshkov-Glick (LMG) model of interacting fermions, where the Hamiltonian transformation corresponds to an orbital rotation. We use a mapping where the number of qubits scales with the $\mathrm{logarithm}$ of the size of the effective model space, rather than the particle number.

Results: HL-VQE is found to provide an exponential improvement in LMG-model calculations of the ground-state energy and wave function, compared to naive truncations without Hamiltonian learning, throughout a significant fraction of the Hilbert space. In the context of EFT, this corresponds to counterterms scaling exponentially with the cutoff as opposed to power law. Implementations on IBM's QExperience quantum computers and simulators for one- and two-qubit effective model spaces are shown to provide accurate and precise results, reproducing classical predictions.

Conclusions: For a range of parameters defining the LMG model, the HL-VQE algorithm is found to have better scaling of quantum resources requirements than previously explored algorithms. In particular, the HL-VQE scales efficiently over a large fraction of the model space, in contrast to VQE alone. This work constitutes a step in the development of entanglement-driven quantum algorithms for descriptions of nuclear many-body systems. This, in part, leverages the potential of noisy intermediate-scale quantum (NISQ) devices. The exponential scaling of counterterms observed in this study suggests the possibility of more general applicability to other nonperturbative EFTs.

Level structures of ${}^{110}\mathrm{Ag}$ were studied by in-beam $\gamma$-ray spectroscopic techniques using the ${}^7\mathrm{Li}+{}^{110}\mathrm{Pd}$ reaction at a beam energy of 46 MeV. Two new positive-parity rotational bands were observed, and were assigned to the $\pi g_{9/2}\otimes \nu d_{5/2}$, and $\pi g_{9/2}\otimes \nu d_{3/2}$ configurations based on the particle-rotor model and geometrical model calculations. Furthermore, the systematic studies of the $B\left(M1\right)/B\left(E2\right)$ ratios and signature splitting for the positive-parity $\pi g_{9/2}\otimes \nu g_{7/2}$ bands in odd-odd nuclei ${}^{106,108,110}\mathrm{Ag}$ and positive-parity $\pi g_{9/2}$ bands in odd-$A$ nuclei ${}^{105,107,109}\mathrm{Ag}$ were performed, and it was found that these bands systematically show enhanced $B\left(M1\right)/B\left(E2\right)$ ratios at the band crossing regions and different behaviors of signature splitting before and after the backbends. In addition, the signature inversion is also observed in odd-odd and odd-$A$ silver isotopes.

A set of hadronic equations of state derived from covariant density functional theory and constrained by terrestrial experiments, and astrophysical observations, in particular by the NICER experiment inferences is used to explore the universal relations among the global properties of compact stars containing heavy baryons at high densities. We confirm the validity of universal $I$-Love-$Q$ relations connecting the moment of inertia $\left(I\right)$, the tidal deformability ($\mathrm{\Lambda }$), and the spin-induced quadrupole moment ($Q$) for isolated nonrotating stars. We further confirm the validity of the $I\text{−}C\text{−}Q$ relations connecting the moment of inertia, compactness $\left(C\right)$, and quadrupole moment for uniformly and slowly rotating stars, and extend the validity of these relations to maximally rotating sequences. We then investigate the relations between integral parameters of maximally rotating and static compact stars. The universalities are shown to persist for equations of state and compositions containing hyperons and $\mathrm{\Delta }$ degrees of freedom. When heavy baryons are included, however, the radial profiles of integrands in expressions of global properties exhibit “bumps”, which are not present in the case of nucleonic stars in which case the profiles are smooth. We determine the coefficients entering the universal relations in the case of hyperonic and $\mathrm{\Delta }$-resonance containing stars.

The deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) is employed to study the ground-state properties of Kr and Sr isotopes. Based on the constrained DRHBc calculations, it is found that Kr and Sr isotopes with $N=50$ are spherical, while the nuclei just away from $N=50$ generally have soft potential energy curves. Further moving along the isotopic chains in both neutron-rich and neutron-deficient directions, there are generally two minima at oblate and prolate sides for nuclear potential energy curves, where possible candidates for shape coexistence are found. The dynamical correlations are crucial to describe the properties of nuclei with soft potential energy curves or shape coexistence, e.g., the binding energies, two-neutron separation energies, deformations, and charge radii, which are considered with the two-dimensional collective Hamiltonian method. In addition, the constrained DRHBc calculations would be helpful to distinguish the oblate or prolate shape for the nuclei with deformation $|{\beta }_2|\gtrsim 0.3$ by combining with the experimental charge radii and absolute values of deformations.

The transverse momentum per particle, $\left[p_t\right]$, fluctuates event by event in ultrarelativistic nucleus-nucleus collisions, for a given multiplicity. These fluctuations are small and approximately Gaussian, but a nonzero skewness has been predicted on the basis of hydrodynamic calculations, and seen experimentally. We argue that the mechanism driving the skewness is that, if the system thermalizes, the mean transverse momentum increases with impact parameter for a fixed collision multiplicity. We postulate that fluctuations are Gaussian at fixed impact parameter, and that non-Gaussianities solely result from impact parameter fluctuations. Using recent data on the variance of $\left[p_t\right]$ fluctuations, we make quantitative predictions for their skewness and kurtosis as a function of the collision multiplicity. We predict, in particular, a spectacular increase of the skewness below the knee of the multiplicity distribution, followed by a fast decrease.

We study procedures for discriminating combinatorial jets in a high background environment, such as a heavy-ion collision from signal jets arising from a hard scattering. We investigate a population of jets clustered from a combined pythia$+$tenngen event, focusing on jets, which can unambiguously be classified as signal or combinatorial jets. By selecting jets based on their kinematic properties, we investigate whether it is possible to separate signal and combinatorial jets without biasing the signal population significantly. We find that after a loose selection on the jet area, surviving combinatorial jets are dominantly imposters, combinatorial jets with properties that are indistinguishable from signal jets. We also find that after a loose selection on the leading hadron momentum, surviving combinatorial jets are still dominantly imposters. We use rule extraction, a machine learning technique, to extract an optimal kinematic selection from a random forest trained on our population of jets. In general, this technique found a stricter kinematic selection on the jet's leading hadron momentum to be optimal. We find that it is possible to suppress combinatorial jets significantly using this machine learning-based selection but that some signal is removed as well. Due to this stricter kinematic selection, we find that the surviving signal is biased towards quarklike jets. Since similar selections are used in many measurements, this indicates that those measurements are biased towards quarklike jets as well. These studies should motivate an increased emphasis on assumptions made when suppressing and subtracting combinatorial background and the biases introduced by methods for doing so.

Recently the interacting boson model with SU(3) higher-order interactions was proposed by one of the authors, in which new $\gamma$ softness can emerge. This stimulates further discussion on the connections between the new $\gamma$ softness and realistic $\gamma$-soft nuclei. In this paper, E(5)-like $\gamma$ softness arises when the SU(3) fourth-order interaction ${\widehat{C}}_2^2\left[\text{SU(3)}\right]$ is considered. The corresponding transitional behaviors are similar to those from the U(5) limit to the O(6) limit in the previous interacting boson model, IBM-1, which provides a novel perspective for understanding the new model. Low-lying spectra, $B\left(E2\right)$ values, and quadrupole moment of the first $2_1^{+}$ state are investigated. The E(5)-like nucleus ${}^{82}\mathrm{Kr}$ is exemplified, where the calculated low-lying level energies and the associated $B\left(E2\right)$ values fit very well with the experimental data.