We present quantum Monte Carlo calculations of magnetic form factors in $A=6–10$ nuclei, based on Norfolk two- and three-nucleon interactions, and associated one- and two-body electromagnetic currents. Agreement with the available experimental data for ${}^6\mathrm{Li}$, ${}^7\mathrm{Li}$, ${}^9\mathrm{Be}$, and ${}^{10}\mathrm{B}$ up to values of momentum transfer $q\sim 3{\mathrm{fm}}^{-1}$ is achieved when two-nucleon currents are accounted for. We present a set of predictions for the magnetic form factors of ${}^7\mathrm{Be}$, ${}^8\mathrm{Li}$, ${}^9\mathrm{Li}$, and ${}^9\mathrm{C}$. In these systems, two-body currents account for $\sim 40\%–60\%$ of the total magnetic strength. Measurements in any of these radioactive systems would provide valuable insights on the nuclear magnetic structure emerging from the underlying many-nucleon dynamics. A particularly interesting case is that of ${}^7\mathrm{Be}$, as it would enable investigations of the magnetic structure of mirror nuclei.

In this Letter we report on effects of nucleon-nucleon correlations probed in nucleon transfer reactions with heavy ions. We measured with high efficiency and resolution a complete set of observables for neutron transfer channels in the ${}^{206}\mathrm{Pb}+{}^{118}\mathrm{Sn}$ system employing a large solid angle magnetic spectrometer, which allowed us to study a wide range of internuclear distances via a detailed excitation function. The coupled channel theory, based on an independent particle transfer mechanism, follows the experimental transfer probabilities for one- and two-neutron pick-up and stripping channels. The experimental two-neutron transfer cross sections indicate that in reactions between pair-vibrational (closed shell) and pair-rotational (open shell) nuclei, correlations manifest via pair-addition and pair-removal modes, which constitute one of the elementary modes of excitations in nuclei.

The shape phase transition for certain isotope or isotone chains, associated with the quantum phase transition of finite nuclei, is an intriguing phenomenon in nuclear physics. A notable case is the Xe isotope chain, where the structure transits from a $\gamma$-soft rotor to a spherical vibrator, with the second-order shape phase transition occurring in the vicinity of ${}^{128–130}\mathrm{Xe}$. In this Letter, we focus on investigating the $\gamma$-soft deformation of ${}^{129}\mathrm{Xe}$ associated with the second-order shape phase transition by constructing novel correlators for ultrarelativistic ${}^{129}\mathrm{Xe}+{}^{129}\mathrm{Xe}$ collisions. In particular, our iEBE-VISHNU model calculations show that the correlation between elliptic flow $v_2$ and mean transverse momentum $[p_T]$, denoted as ${\rho }_2$, as well as the $[p_T]$ fluctuation ${\mathrm{\Gamma }}_{p_T}$, which were previously used to claim the evidence of the rigid triaxial deformation of ${}^{129}\mathrm{Xe}$, can also be well explained by the $\gamma$-soft deformation of ${}^{129}\mathrm{Xe}$. We further propose two novel correlators ${\rho }_{4,2}$ and ${\rho }_{2,4}$, which carry nontrivial higher-order correlations and show unique capabilities to distinguish between the $\gamma$-soft and the rigid triaxial deformation of ${}^{129}\mathrm{Xe}$ in ${}^{129}\mathrm{Xe}+{}^{129}\mathrm{Xe}$ collisions at the LHC. The present study provides a novel way to explore the second-order shape phase transition of finite nuclei with ultrarelativistic heavy ion collisions.

Utilizing a comprehensive $(3+1)D$ relativistic hydrodynamic framework with multiple conserved charge currents and charge-dependent lattice-QCD-based equation of state, we study the baryon and electric charge number deposition at midrapidity in isobar $\mathrm{Ru}+\mathrm{Ru}$ and $\mathrm{Zr}+\mathrm{Zr}$ collisions at the center of mass energy $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$. Comparing our predictions with upcoming experimental data from the Relativistic Heavy Ion Collider will shed light on the existence of baryon junctions.

Nuclear energy levels are usually calculated using conventional diagonalization methods in the framework of the configuration-interaction (CI) shell model but these methods are prohibited in very large model spaces. The shell model Monte Carlo (SMMC) method is a powerful technique for calculating thermal and ground-state observables of nuclei in very large model spaces, but it is challenging to extract nuclear spectra in this approach. We present a novel method to extract within SMMC low-lying energy levels for given values of a set of good quantum numbers such as spin and parity. The method is based on imaginary-time correlation matrices (ITCMs) of one-body densities that satisfy asymptotically a generalized eigenvalue problem. We validate the method in a light nucleus that allows comparison with exact diagonalization results of the CI shell-model Hamiltonian. The method is broadly applicable to quantum many-body systems in other disciplines.

We extend the QCD Parton Model analysis using a factorized nuclear structure model incorporating individual nucleons and pairs of correlated nucleons. Our analysis of high-energy data from lepton deep-inelastic scattering, Drell-Yan, and $W$ and $Z$ boson production simultaneously extracts the universal effective distribution of quarks and gluons inside correlated nucleon pairs, and their nucleus-specific fractions. Such successful extraction of these universal distributions marks a significant advance in our understanding of nuclear structure properties connecting nucleon- and parton-level quantities.

Several protocols are proposed to build continuous energy surfaces of many-body quantum systems, regarding both energy and states. The standard variational principle is augmented with constraints on state overlap, ensuring arbitrary precision on continuity. As an illustration, the lowest energy and excited state paths relevant for the ${}^{240}\mathrm{Pu}$ asymmetric fission are studied. The scission is clearly signed, with a neutron excess in the neck, the ultimate glue before its rupture. Our approach can potentially connect any couple of Hilbert space states, which opens up new horizons for various applications.

To distill the essential elements of nuclear binding, we seek the simplest Hamiltonian capable of modeling atomic nuclei with percent-level accuracy. A critical aspect of this endeavor consists of accurately solving the quantum many-body problem without incurring an exponential computing cost with the number of nucleons. We address this challenge by leveraging a variational Monte Carlo method based on a highly expressive neural-network quantum state ansatz. In addition to computing binding energies and charge radii of nuclei with up to $A=20$ nucleons, by evaluating their magnetic moments, we demonstrate that neural-network quantum states are able to correctly capture the self-emerging nuclear shell structure. To this end, we introduce a novel computational protocol based on adding an external magnetic field to the nuclear Hamiltonian, which allows the neural network to learn the preferred polarization of the nucleus within the given magnetic field.

The excitation of the ${}^{181m}\mathrm{Ta}$ isomer in the laser-plasma scenario was claimed to have been observed more than two decades ago. However, the reported experimental findings—and the respective high excitation rate—were later questioned as they could not be reproduced theoretically. The controversy has remained open ever since. In this work, we reinvestigate both theoretically and experimentally the ${}^{181m}\mathrm{Ta}$ nuclear excitation in an optical laser-generated plasma. Experimentally we have found no evidence for such an excitation process as consistently predicted by previous and our theoretical models.

High-precision mass measurements of exotic ${}^{95–97}\mathrm{Ag}$ isotopes close to the $N=Z$ line have been conducted with the JYFLTRAP double Penning trap mass spectrometer, with the silver ions produced using the recently commissioned inductively heated hot cavity catcher laser ion source at the Ion Guide Isotope Separator On-Line facility. The atomic mass of ${}^{95}\mathrm{Ag}$ was directly determined for the first time. In addition, the atomic masses of $\beta$-decaying $2^{+}$ and $8^{+}$ states in ${}^{96}\mathrm{Ag}$ have been identified and measured for the first time, and the precision of the ${}^{97}\mathrm{Ag}$ mass has been improved. The newly measured masses, with a precision of $\approx 1\mathrm{keV}/{\mathrm{c}}^2$, have been used to investigate the $N=50$ neutron shell closure, confirming it to be robust. Empirical shell-gap and pairing energies determined with the new ground-state mass data are compared with the state-of-the-art ab initio calculations with various chiral effective field theory Hamiltonians. The precise determination of the excitation energy of the ${}^{96m}\mathrm{Ag}$ isomer in particular serves as a benchmark for ab initio predictions of nuclear properties beyond the ground state, specifically for odd-odd nuclei situated in proximity to the proton dripline below ${}^{100}\mathrm{Sn}$. In addition, density functional theory calculations and configuration-interaction shell-model calculations are compared with the experimental results. All theoretical approaches face challenges to reproduce the trend of nuclear ground-state properties in the silver isotopic chain across the $N=50$ neutron shell and toward the proton dripline.

Current bounds on the neutrino Majorana mass are affected by significant uncertainties in the nuclear calculations for neutrinoless double-beta decay. A key issue for a data-driven improvement of the nuclear theory is the actual value of the axial coupling constant $g_{\mathrm{A}}$, which can be investigated through forbidden $\beta$ decays. We present the first measurement of the 4th-forbidden $\beta$ decay of ${}^{115}\mathrm{In}$ with a cryogenic calorimeter based on indium iodide. Exploiting the enhanced spectrum-shape method for the first time to this isotope, our study accurately determines simultaneously spectral shape, $g_{\mathrm{A}}$, and half-life. The interacting shell model, which best fits our data, indicates a half-life for this decay at $T_{1/2}=(5.26\pm 0.06)\times {10}^{14}\mathrm{yr}$.

This Letter presents the most precise measurement to date of the matter-antimatter imbalance at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. Using the Statistical Hadronization framework, it is possible to obtain the value of the electric charge and baryon chemical potentials, ${\mu }_Q=-0.18\pm 0.90\mathrm{MeV}$ and ${\mu }_B=0.71\pm 0.45\mathrm{MeV}$, with unprecedented precision. A centrality-differential study of the antiparticle-to-particle yield ratios of charged pions, protons, $\mathrm{\Omega }$ baryons, and light (hyper)nuclei is performed. These results indicate that the system created in Pb-Pb collisions at the LHC is on average baryon-free and electrically neutral at midrapidity.

Isomer spectroscopy of heavy neutron-rich nuclei beyond the $N=126$ closed shell has been performed for the first time at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. New millisecond isomers have been identified at low excitation energies, 985.3(19) keV in ${}^{213}\mathrm{Tl}$ and 874(5) keV in ${}^{215}\mathrm{Tl}$. The measured half-lives of 1.34(5) ms in ${}^{213}\mathrm{Tl}$ and 3.0(3) ms in ${}^{215}\mathrm{Tl}$ suggest spins and parities $11/2^{-}$ with the single proton-hole configuration $\pi h_{11/2}$ as leading component. They are populated via $E1$ transitions by the decay of higher-lying isomeric states with proposed spin and parity $17/2^{+}$, interpreted as arising from a single $\pi s_{1/2}$ proton hole coupled to the $8^{+}$ seniority isomer in the ${}^{A+1}\mathrm{Pb}$ cores. The lowering of the $11/2^{-}$ states is ascribed to an increase of the $\pi h_{11/2}$ proton effective single-particle energy as the second $\nu g_{9/2}$ orbital is filled by neutrons, owing to a significant reduction of the proton-neutron monopole interaction between the $\pi h_{11/2}$ and $\nu g_{9/2}$ orbitals. The new $ms$ isomers provide the first experimental observation of shell evolution in the almost unexplored $N>126$ nuclear region below doubly magic ${}^{208}\mathrm{Pb}$.

Excited states in ${}^{10}\mathrm{B}$ were populated with the ${}^{10}\mathrm{B}(p,p^{\prime }\gamma ){{}^{10}\mathrm{B}}^{*}$ reaction at 8.5 MeV and their $\gamma$ decay was investigated via coincidence $\gamma$-ray spectroscopy. The emitted $\gamma$ rays were measured using large-volume ${\mathrm{LaBr}}_3:\mathrm{Ce}$ and ${\mathrm{CeBr}}_3$ detectors placed in anti-Compton shields. This allowed the observation of weak $\gamma$-ray transitions, such as the $M3$ transition between the $J^{\pi },T=0^{+},1$ isobaric analog state (IAS) and the $J^{\pi },T=3^{+},0$ ground state and the $E2$ transition between the $J^{\pi },T=2_1^{+},0$ state and the IAS, i.e., performing measurements of branching ratios at the level of $\lambda \ge {10}^{-4}$. For the first time in ${}^{10}\mathrm{B}$, the competing $M1$ and $M3$ transitions from the decay of the IAS have been observed in a $\gamma$ spectroscopy experiment. The experimental results are compared with ab initio no-core shell model calculation using the newest version of the local position-space chiral ${\mathrm{N}}^3\mathrm{LO}$ nucleon-nucleon interaction. The calculations reproduce correctly the ordering of the bound states in ${}^{10}\mathrm{B}$, and are in reasonable agreement with the observed branching ratios and reduced transition probabilities.

We report a measurement of exclusive $J/\psi$ and $\psi (2s)$ photoproduction in $\mathrm{Au}+\mathrm{Au}$ ultraperipheral collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$ using the STAR detector. For the first time, (i) the $\psi (2s)$ photoproduction in midrapidity at the Relativistic Heavy-Ion Collider has been experimentally measured; (ii) nuclear suppression factors are measured for both the coherent and incoherent $J/\psi$ production. At average photon-nucleon center-of-mass energy of 25.0 GeV, the coherent and incoherent $J/\psi$ cross sections of Au nuclei are found to be $71\pm 10\%$ and $36\pm 7\%$, respectively, of that of free protons. The stronger suppression observed in the incoherent production provides a new experimental handle to study the initial-state parton density in heavy nuclei. Data are compared with theoretical models quantitatively.