The ${}^{53}\mathrm{Co}19/2^{-}$ isomer at 3174 keV is a special metastable state that is the first proton emitter discovered. It is also important in nuclear astrophysics. In this paper, we present ab initio calculations that provide a comprehensive understanding of the structure, beta decay, and formation mechanism of the isomer. The calculations were performed by the valence-space in-medium similarity renormalization group based on chiral effective field theory ($\chi \mathrm{EFT}$) nuclear forces with the three-nucleon force included. It is found that the three-nucleon force plays a crucial role in the formation of the $19/2^{-}$ isomer. The ${}^{53m}\mathrm{Co}(19/2^{-})$ lifetime is mainly determined by the $\beta$ decay into ${}^{53m}\mathrm{Fe}(19/2^{-})$, which was calculated with a quenching factor obtained by considering the $\chi \mathrm{EFT}$ two-body currents.

The in-medium similarity renormalization group (IMSRG) is a powerful and flexible many-body method to compute the structure of nuclei starting from nuclear forces. Recent developments have extended the IMSRG from its standard truncation at the normal-ordered two-body level, the IMSRG(2), to a precision approximation including normal-ordered three-body operators, the IMSRG(3)-$N^7$. This improvement provides a more precise solution to the many-body problem and makes it possible to quantify many-body uncertainties in IMSRG calculations. We explore the structure of ${}^{44,48,52}\mathrm{Ca}$ using the IMSRG(3)-$N^7$, focusing on understanding existing discrepancies of the IMSRG(2) to experimental results. We find a significantly better description of the first $2^{+}$ excitation energy of ${}^{48}\mathrm{Ca}$, improving the description of the shell closure at $N=28$. At the same time, we find that the IMSRG(3)-$N^7$ corrections to charge radii do not resolve the systematic underprediction of the puzzling large charge radius difference between ${}^{52}\mathrm{Ca}$ and ${}^{48}\mathrm{Ca}$. We present estimates of many-body uncertainties of IMSRG(2) calculations applicable also to other systems based on the size extensivity of the method.

Excited states of ${}^{90}\mathrm{Zr}$ and ${}^{92}\mathrm{Zr}$ were investigated using the fusion reactions ${}^6\mathrm{Li}+{}^{89}\mathrm{Y}$ and ${}^{14}\mathrm{N}+{}^{82}\mathrm{Se}$, respectively. Based on the experimental data, 5 and 18 new $\gamma$ rays have been added to the level schemes of ${}^{90}\mathrm{Zr}$ and ${}^{92}\mathrm{Zr}$, respectively. The level structures of ${}^{90}\mathrm{Zr}$ and ${}^{92}\mathrm{Zr}$ have been interpreted with shell-model calculations using the GWBXG and SNET effective interactions. The neutron core-breaking and the importance of the $1g_{7/2}$ and $1h_{11/2}$ orbits for high-spin states of ${}^{92}\mathrm{Zr}$ were discussed. The excitation energy of the neutron core-breaking of nuclei in the $A=90$ region was compared.

Intermediate mass fragments ejected during the deexcitation of excited projectilelike fragments may promptly decay following ejection; the daughter particles that are subsequently produced are subject to interactions with the residual nucleus that affect final-state observables, a process herein referred to as post-breakup Coulomb acceleration. A simple classical Coulomb interaction model was used to study modification of ${}^8\mathrm{Be}$ ($2^{+}$), ${}^5\mathrm{Li}$ ($3/2^{-}$), ${}^7\mathrm{Li}$ ($7/2^{-}$), ${}^7\mathrm{Be}$ ($7/2^{-}$), and states in ${}^{12}\mathrm{B}$ emitted following heavy-ion collisions of ${}^{28}\mathrm{Si}+{}^{12}\mathrm{C}$ at 35 MeV/nucleon. In contrast to previous work studying ${}^8\mathrm{Be}$ ($2^{+}$), excellent agreement between simulation and experiment was obtained using only Coulomb forces when either a Lorentzian or $R$-matrix line shape was used to describe the initial relative energy rather than a Gaussian. In consideration of the obtained results, improvements to the model and evaluation of experimental data are discussed as future directions, but it was concluded that the effects observed in the present data can be accurately described using only elements of classical mechanics and that the process is largely understood for a wide range of state lifetimes and mass and charge (a)symmetries.

Coupling to transfer reactions is a long-standing problem in heavy-ion fusion at near-barrier energies. The ${}^{18}\mathrm{O}+{}^{58}\mathrm{Ni}$ system, that was claimed to show a large sub-barrier fusion enhancement, is a typical case to demonstrate the coupled-channels effects of positive $Q$-value two-neutron ($2n$) transfer based on the existing experimental data. We remeasured the near-barrier fusion excitation function of ${}^{18}\mathrm{O}+{}^{58}\mathrm{Ni}$ extending to lower energies by detecting the fusion evaporation residues. In order to understand the effects of couplings to neutron transfers, coupled-reaction-channels calculations by the code fresco were performed in a nonadjustable mode. Results show that couplings to low-lying collective excitations and one-neutron transfer are enough to explain the experimental fusion excitation function and barrier distribution. No evidence shows a sub-barrier fusion enhancement attributed to positive $Q$-value $2n$ stripping.

Accurate prediction of isotope production near the neutron and proton drip lines is critical for optimizing experimental designs in new rare isotope beam facilities. This study presents a systematic multimodel comparison of $Q_g$ systematics for fragment production cross sections, where $Q_g$ represents the mass excess difference between the projectile nucleus ($Z_p,A_p$) and the fragment nucleus ($Z_f,A_f$), that is, $Q_g=ME(Z_p,A_p)-ME(Z_f,A_f)$. The investigation evaluates the predictive capabilities of the model for light neutron-rich isotopes through the analysis of ${}^{40}\mathrm{Ar}{+}^9\mathrm{Be}$ projectile fragmentation reactions within an extensive energy range from $57A$ MeV to $1A$ GeV. The models used are the FRACS parametrizations and the newly developed Bayesian neural network (BNN) model. The results demonstrate generally consistent extrapolation trends among the FRACS predictions, the BNN calculations, and the $Q_g$ systematics, with discrepancies primarily observed for fragments approaching the projectile mass. Experimental measurements combined with theoretical extrapolations reveal compelling evidence for $N=16$ shell closure in fluorine and neon, concurrent with the disappearance of the conventional magic number $N=20$ in neutron-rich neon, sodium, and magnesium isotopes.

Global polarization of hyperons induced by the local vorticity of the medium created in heavy-ion collisions at energies $2.3\le \sqrt{s_{NN}}\le 11.5\mathrm{GeV}$ is calculated in the parton-hadron-string dynamic (phsd) model. The separation of spectator nucleons and the fluidization of the generated particle distributions are performed. The polarization of all antihyperon species is found to be significantly larger than that of hyperons. The $\overline{\mathrm{\Xi }}$ hyperons are found to be polarized as strongly as $\overline{\mathrm{\Lambda }}\text{'s}$, but $\mathrm{\Xi }$ hyperons have weaker polarization compared to $\mathrm{\Lambda }\text{'s}$. The $\mathrm{\Omega }$ and $\overline{\mathrm{\Omega }}$ polarizations show the strongest dependence on the collision energy. Despite the strong polarization of the produced $\mathrm{\Lambda }\text{'s}$ and $\overline{\mathrm{\Lambda }}\text{'s}$ induced by the vortical flows in the medium, the observed polarization signal is significantly depleted because of the feed-down from weak and electromagnetic decays of heavier hyperons. Particularly strong suppression is found to be due to electromagnetic decays of ${\mathrm{\Sigma }}^0$ hyperons, whose multiplicities obtained in the transport are poorly constrained both from the microscopic input of the ${\mathrm{\Sigma }}^0$ production reactions and from the experimental data. The final $\mathrm{\Lambda }\left(\overline{\mathrm{\Lambda }}\right)$ polarization signal strongly depends on the ${\mathrm{\Sigma }}^0$ multiplicity generated in the model. With all these effects we can reproduce the measured global $\mathrm{\Lambda }$ polarization in collisions at $\sqrt{s_{NN}}=7.7$ and $11.5\mathrm{GeV}$ and the global $\overline{\mathrm{\Lambda }}$ polarization at 11.5 GeV. For energies $\lesssim 3\mathrm{GeV}$, the calculated $\mathrm{\Lambda }$ polarization is smaller than the observed one. The polarization of $\mathrm{\Xi }\left(\overline{\mathrm{\Xi }}\right)$ hyperons is calculated. The signal of $\mathrm{\Xi }\left(\overline{\mathrm{\Xi }}\right)$ polarization is argued to be insensitive to feed-down effects and be, therefore, a more direct probe of the degree of the vorticity in the system.

Production and in-medium modification of hidden strange $\varphi$ mesons are studied in proton-nucleus reactions: $\mathrm{p}+\mathrm{C}$, $\mathrm{p}+\mathrm{Cu}$, and $\mathrm{p}+\mathrm{Pb}$, at 12 $\mathrm{GeV}/c$, partially measured by the KEK E325 Collaboration via the dilepton decay mode. This work is based on the off-shell microscopic parton-hadron-string dynamics transport approach, which provides the dynamical description of strongly interacting hadronic and partonic degrees of freedom in dense matter, and especially makes it possible to simulate in-medium off-shell dynamics of the $\varphi$ meson in the reactions studied. Different in-medium scenarios for the modification of the $\varphi$-meson spectral function in nuclear matter are investigated: (i) dropping pole mass, (ii) collisional broadening, and (iii) simultaneous dropping pole mass and collisional broadening. Even though the $\varphi$ meson production in $\mathrm{p}+\mathrm{A}$ reactions occurs only at densities around or below normal nuclear matter density ${\rho }_0$, we find visible modifications of the generated dilepton spectra for the in-medium scenarios compared to the vacuum distribution.

The properties of dilute neutron matter are mostly determined by the $s$-wave two-body (2N) interaction, while three-body (3N) interactions are suppressed by the Pauli principle. In a previous work, we showed that it can be advantageous to use renormalization group based effective interactions with cutoffs scaled with the Fermi momentum, especially at low densities. In that case, induced 3N interactions may become important. In this work, we compute the 3N interaction induced by the similarity renormalization group flow of the $s$-wave 2N interaction. We work in the momentum-space hyperspherical partial wave basis and investigate its convergence properties. Then we study the effect of the induced 3N interaction on the equation of state of dilute neutron matter. We observe that the cutoff dependence of the equation of state is strongly reduced when the effect of induced 3N interaction is included.

Scattering probes the internal structure of quantum systems. We calculate the two-particle elastic scattering phase shift for a short-ranged interaction on a quantum computer. Short-ranged interactions with a large scattering length or shallow bound state describe a universality class that is of interest in atomic, condensed matter, nuclear, and particle physics. The phase shift is calculated by relating it to the ground-state energy of the interacting particles in a harmonic trap. The relaxation method is used as the variational quantum eigensolver for the ground-state calculation. Schmidt decomposition is used to reduce quantum circuits nominally requiring tens of qubits to two-qubit circuits, thus reducing the noise in quantum measurements. Calculations in multiparticle systems with many-body interactions would benefit from this reduction of qubits in noisy quantum processors.

One-proton emission from the ${}^{102}\mathrm{Sb}$ nucleus is discussed, assuming an inert ${}^{100}\mathrm{Sn}$ core and the valence proton and neutron. There are experimentally measured bound states in the ${}^{100}\mathrm{Sn}$-neutron system, whereas no particle-bound ${}^{100}\mathrm{Sn}$-proton state has been observed. With time-dependent three-body calculations, the $1^{+}$ ground state of ${}^{102}\mathrm{Sb}$ is suggested as a possible proton emitter. This conclusion is reached by assuming a weakening effect on the proton-neutron $\left(pn\right)$ interaction with respect to a bare deuteron. An analogous phenomenon is necessary to reproduce the empirical binding energies of ${}^{42}\mathrm{Sc}$ and ${}^{18}\mathrm{F}$. Continuous shift from the unbound to bound regions by changing the $pn$-interaction strength is demonstrated. The lower limit of lifetime is evaluated as $\tau \gtrsim 4.4\times {10}^{-18}$ s in the no-$pn$-interaction limit. However, the actual lifetime is expected as longer with a finite $pn$ interaction. Observation of a resonant state in ${}^{102}\mathrm{Sb}$ and its decay would provide a benchmark of the $pn$-pairing correlation.

Precise mass measurements of the ground and isomeric states of the odd-odd ${}^{108,110,112,114,116}\mathrm{Rh}$ were performed using the Canadian Penning Trap at Argonne National Laboratory, showing good agreement with recent JYFLTRAP measurements. A new possible isomeric state of ${}^{114}\mathrm{Rh}$ was also observed. These isotopes are part of the longest odd-odd chain of identical ground-state spin-parity assignment of $1^{+}$, spanning ${}^{104–118}\mathrm{Rh}$, despite being in a region of deformation. Realistic phenomenological mean-field calculations using the “universal” Wood-Saxon Hamiltonian were performed, which explained this phenomenon for the first time. In addition, multiquasiparticle blocking calculations were performed to study the configuration of low-lying states in the odd-odd Rh nuclei, elucidating anomalous isomeric yield ratio observed for ${}^{114}\mathrm{Rh}$.

Radiative processes, where a photon/neutrino is emitted as a result of a collision or decay of a particle, play a central role in atomic, nuclear, and particle physics. Their rate is determined by certain off-diagonal matrix elements between different initial and final states. We propose a method to compute them using quantum computers. It relies on a single extra qubit that, in a certain sense, represents the photon/neutrino. The generic formula relating this matrix element to the amplitude and frequency of oscillations of the extra qubit is derived for the near-resonance case. We demonstrate the feasibility of the method by using it in actual quantum computations and simulations of simple systems.

Drag and diffusion coefficients of the heavy quarks (HQs), such as charm and bottom, are one of the prime tools for discerning the properties of the deconfined quantum chromo-dynamics (QCD) medium created in heavy-ion collision experiments. The innate nonperturbative nature of the QCD medium renders it imperative to estimate the transport coefficients in that domain. The present work evaluates the drag and diffusion coefficients of the moving HQs interacting with the medium particles via two-body collisional and three-body radiative processes to the first order in opacity by employing the Gribov mechanism for the nonperturbative regime. We proffer the latest results of the HQ transport coefficients computed for the nonperturbative and noneikonal gluon radiation off the HQs. The calculations show significant increments of the transport coefficients with the increasing noneikonality by juxtaposing the results with those of the perturbative and eikonal regions. We hope to shed fresh light on explaining the experimental data on the nuclear modification factor $R_{AA}$ and the elliptic flow $v_2$ of the HQs by advocating for the importance of the noneikonality of the gluon radiation off the HQs.

Collective flow coefficients and spin polarization are valuable probes of the geometry and flow velocity field of the quark-gluon plasma (QGP) produced in relativistic heavy-ion collisions. Using a modified TRENTo initial condition coupled to a ($3+1$)-dimensional [(3+1)D] viscous hydrodynamic model CLVisc, we study the directed flow and elliptic flow coefficients of hadrons, together with the global polarization of $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ hyperons in asymmetric $\mathrm{Cu}+\mathrm{Au}$ collisions. We extend the 2D TRENTo model to the 3D space, and find that the initial tilted geometry of the QGP fireball with respect to the longitudinal direction leads to a decrease of directed flow from positive to negative values with increasing pseudorapidity, an enhancement of elliptic flow at forward and backward pseudorapidities, and a nonmonotonic dependence of global polarization on the transverse momentum of hyperons. The initial longitudinal flow velocity gradient further enhances the values of directed flow and global polarization. Our model calculation provides a satisfactory description of the rapidity, transverse momentum, and centrality dependences of the directed flow of charged hadrons in $\mathrm{Cu}+\mathrm{Au}$ collisions for the first time, and we propose that such asymmetric heavy-ion collisions create a better environment for studying the initial tilted geometry and longitudinal flow field of the QGP than symmetric $\mathrm{Au}+\mathrm{Au}$ collisions do.

In nuclear astrophysics, the accurate determination of nuclear reaction cross sections at astrophysical energies is critical for understanding stellar evolution and nucleosynthesis. This study focuses on the ${}^{12}\mathrm{C}(p,\gamma ){}^{13}\mathrm{N}$ reaction, which takes part in the CNO cycle and is significant for determining the ${}^{12}\mathrm{C}/{}^{13}\mathrm{C}$ ratio in stellar interiors. Data from various studies, including recent LUNA measurements, reveal high discrepancies in cross-section values, underscoring the need for robust fitting approaches. Utilizing the R-matrix theory, we compare different frequentist and Bayesian methodologies for estimating reaction cross sections and their uncertainties. The analysis evaluates the strengths and weaknesses of different statistical techniques, highlighting the importance of systematic uncertainty treatment and the estimate of covariance matrix estimation to enhance the reliability and reproducibility of uncertainty estimates in nuclear astrophysics.

Shape coexistence in Zr isotopes has been studied through the $\beta$ decay of isotopically purified beams of ${}^{98}\mathrm{Rb}$ and ${}^{100}\mathrm{Rb}$ at the Accélérateur Linéaire et TANDEM d'Orsay (ALTO) facility using the new setup COnversion electrons Chasing at Orsay (COeCO). The electric monopole transition strengths between first excited $0^{+}$ state and ground-state have been extracted from half-live measurements in ${}^{98}\mathrm{Zr}$ and ${}^{100}\mathrm{Zr}$. These experimental data were interpreted—along with $B\left(E2\right)$ values—in a two-state mixing model to extract mean-square charge radii of excited $0^{+}$ states and compared to existing data for ground states in the Zr isotopic line, showing quite unexpected and exceptional agreement. Comparison with beyond self-consistent mean field calculation sheds new light on the nature of the coexisting shapes around the $N=58\text{−}60$ transition region.

We investigate the properties of neutron stars with antikaon condensation in the framework of the relativistic mean-field (RMF) model with a $\sigma$-cut potential. The well-known RMF models, TM1 and TM1e, are used to analyze the structure and composition of neutron stars. The antikaon condensation part of the equation of state (EoS) is constrained from the experimental data of $K^{-}$ atomic and kaon-nucleon scattering. The $\sigma$-cut potential, which is known to make the equation of state stiffer at high densities, is modulated by a free parameter $f_s$. Our present analysis suggests that one can obtain neutron-star configurations heavier than $2M_{\odot }$ with antikaon condensates in most cases for $f_s=0.6$. The antikaon phase transition is second order for $f_s=0.6$ for both TM1 and TM1e parameter sets. The calculated global properties of neutron stars with antikaon condensates, i.e., mass and radius, seem to be in reasonable agreement with other theoretical and observational data.

The relativistic symmetry in the shell evolution in $N=32$ and 34 isotones from Si to Ni is explored based on the relativistic point-coupling model combined with the similarity renormalization group (SRG). Taking the proton pseudospin doublets $\pi 1\tilde{p}$ and $\pi 2\tilde{d}$ and the spin doublets $\pi 1d,\pi 1f,\text{and}\pi 2p$ as examples, the correlations of relativistic symmetry with subshell evolution, proton number, and quantum numbers of states are investigated. The origin and breaking mechanisms of pseudospin symmetry (PSS) and spin symmetry (SS) have been explored by the analytical decomposition of the Dirac Hamiltonian with SRG. The nonrelativistic term primarily determines the PSS quality, while the dynamical term and spin-orbit interaction significantly influence PSS. For SS, the spin-orbit interaction prevails. Despite substantial energy splittings within subshells, the pseudo(spin) doublets display similarities in their lower (upper) wave function components. Notably, PSS restoration is associated with bubblelike structures and subshell emergence/disappearance. A more diffuse potential in exotic nuclei facilitates improved PSS restoration, as demonstrated by the mean field potential $\mathrm{\Sigma }$ and its derivative ${\mathrm{\Sigma }}^{\prime }\left(r\right)$ analysis.