Dense nucleonic matter is of vital importance for understanding compact stars and inferring the transition into deconfined quark phase. We present ab initio exact calculations of infinite nucleonic matter with the state-of-the-art full configuration-interaction quantum Monte Carlo method, enabling us to rigorously benchmark many-body methods and assess the degree to which the nucleonic matter is correlated. Our method has been numerically validated against exact diagonalization within a small model space. Calculations of nucleonic matter using chiral nuclear forces reveal that symmetric nuclear matter is strikingly strongly correlated, raising questions on previous ab initio calculations of nuclear matter with many-body expansion truncations and offering insights into simultaneous descriptions of finite nuclei and infinite nucleonic matter from first principles.

The applicability of hydrodynamics in small collision systems remains controversial due to the small size and short lifetime of the system. In this Letter, we employ viscous anisotropic hydrodynamics (VAH), which incorporates large pressure anisotropies, to study the collectivity in $\mathrm{p}+\mathrm{p}$ collisions at $\sqrt{s}=13\mathrm{TeV}$. VAH provides a good description for $v_2\{2\}$ and $v_3\{2\}$ over a wide range of multiplicities and correctly reproduces the experimentally observed negative $c_2\{4\}$. Traditional second-order viscous hydrodynamics (VH), on the other hand, can describe the measurements, in particular the negative $c_2\{4\}$, only with model parameters for which the bulk of the evolution is characterized by large values of the shear Knudsen number. It also cannot capture the large pressure anisotropy between the longitudinal and transverse directions during the early evolution. These demonstrate the failure of traditional viscous hydrodynamics in small collision systems and establish viscous anisotropic hydrodynamics as a more reliable framework to describe the bulk evolution and the observed anisotropic flow in p–p collisions at the LHC.

High-precision multireflection time-of-flight mass spectrometry has been applied at BigRIPS-SLOWRI of the Radioactive Isotope Beam Factory (RIBF). The atomic mass of ${}^{50}\mathrm{Ar}$ was measured for the first time, and the mass value of ${}^{49}\mathrm{Ar}$ was determined to be 674 keV lower than the one from a previous $B\rho -$ TOF measurement, with a precision improved by a factor of 250. The new mass data enable us to determine the empirical proton-neutron interaction strength in the unconventional doubly magic nucleus ${}^{52}\mathrm{Ca}$. This strength exhibits a conspicuous variation across shell closures, analogously to what observed in classical doubly magic nuclei. Meanwhile, our measurements support the existence of a weak shell effect at $N=32$ in Ar isotopes. To supplement these experimental findings, theoretical calculations were performed for the isotopes of interest, which, compared with data, illustrate the capacity of ab initio expansion methods to capture key quadrupole correlations in doubly open-shell nuclei via an explicit account of nuclear deformation.

The precise quantification of fusion suppression in heavy-projectile induced reactions is obscured by dominant noncompound processes, limited data, and uncertain models. Mass-total kinetic energy (MTKE) distributions for the reaction ${}^{54}\mathrm{Cr}+{}^{209}\mathrm{Bi}$ were measured at three beam energies, $E_{\mathrm{beam}}=261$, 271, and 278 MeV. The fission fragments were detected using the newly developed TOSCA spectrometer setup. This Letter reveals, for the first time, two asymmetric mass modes at $\sim 80\mathrm{u}$ (complementary $\sim 183\mathrm{u}$), and $\sim 105$ u (complementary $\sim 158\mathrm{u}$), likely associated with the spherical $N=50$ shell and the deformed $Z\approx 42/N\approx 94$ shells, respectively. At the lowest energy, the symmetric mode exhibits a narrow, super-short-like width and high correlated TKE caused likely by $Z=50$, $N=82$ shells. The fusion probability (${\mathrm{P}}_{\mathrm{CN}}$) from multi-Gaussian fits to gated mass (and TKE) distributions using a refined tail-subtraction approach to remove the quasifission background remains robust despite model dependence. $P_{\mathrm{CN}}$ peaks near the barrier and decreases on either side, with a slower decrease at the above-barrier energy, differing from the sub-barrier fusion enhancement reported in [Phys. Rev. Lett. 122, 232503 (2019)] and indicating an open question for further study.

Energy correlators have recently attracted significant attention in the study of heavy ion collisions due to their potential to robustly connect experimental measurements with an underlying quantum field theoretic description. While theoretical studies have so far primarily focused on the simplest two-point correlator, mapping out the dynamics of the quark-gluon plasma (QGP) will require developing a theoretical understanding of multipoint energy correlators. In this Letter, we present a systematic theoretical study of multipoint energy correlators for jets fragmenting in a dense quark-gluon plasma, accounting for both the medium’s perturbative modification to the jet and its hydrodynamical backreaction. We consider both the scaling behavior of projected correlators, as well as the shape dependent three-point correlator, highlighting how both provide insight into interactions with the QGP. We discuss the parametric dependence of modifications on the medium scales, opening new opportunities to experimentally separate jet modifications from the medium response. Our results open the door to a systematic exploration of multipoint energy correlators in heavy ion collisions.

According to quantum chromodynamics, at sufficiently high energy, the structure of hadrons reveals a dynamic equilibrium between gluon splitting and gluon recombination—a phenomenon known as saturation. The process of diffractive photonuclear production of a $J/\psi$ vector meson provides a direct insight into the gluon composition of hadrons. The $J/\psi$ production as a function of momentum transferred in the interaction, quantified by the Mandelstam-$t$ variable, serves as an excellent probe for studying the structure of hadrons within the impact-parameter plane, because different ranges in $t$ are sensitive to the dynamics of the gluon field at varying spatial size scales. The ALICE Collaboration has measured the energy dependence of incoherent photonuclear production of $J/\psi$ mesons off lead ions, at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$, for three Mandelstam-$t$ intervals. The energy dependence of the photonuclear cross section at the highest $|t|$ range measured, $(0.81<|t|<1.44){\mathrm{GeV}}^2$, is sensitive to subnucleonic structures of the Pb target. The increase of the cross section with energy at large $|t|$ shows evidence of suppression with respect to the increase seen at low $|t|$. The observed pattern of the energy evolution in data is similar to that of gluon saturation models.

An important validation of nucleosynthesis models of core-collapse supernovae is the comparison of radioisotope predictions to abundances inferred from observations of $\gamma$ rays emitted in remnants. One such isotope, ${}^{44}\mathrm{Ti}$, is especially sensitive to the ${}^{57}\mathrm{Ni}(p,\gamma ){}^{58}\mathrm{Cu}$ reaction rate. Despite this importance, no experimentally constrained rate exists for this reaction. It is thus crucial to determine this rate. GRETINA ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS) was used along with the first use of the Enge split-pole spectrograph at Notre Dame to measure structure properties of ${}^{58}\mathrm{Cu}$ via the ${}^{58}\mathrm{Ni}({}^3\mathrm{He},t){}^{58}\mathrm{Cu}$ reaction. The combined analysis of these complementary data sets allows for precise determination of ${}^{58}\mathrm{Cu}$ level energies, and spins are constrained from analysis of the $\gamma$-ray decay. ${}^{44}\mathrm{Ti}$ yields were found to change by over 25% compared to previous estimates in model calculations using the new experimentally constrained reaction rate.

Our understanding of the origin of heavy elements beyond iron relies on the rapid neutron capture process ($r$ process), which accounts for roughly half of their cosmic abundance. However, the extreme neutron-rich conditions required for the $r$ process involve many nuclei that remain experimentally inaccessible, making theoretical predictions essential. We explore the impact of nuclear masses calculated with the ab initio valence-space in-medium similarity renormalization group, focusing on the region around the $N=82$ shell closure. We show for the first time that such ab initio mass calculations can be used to refine $r$-process predictions compared to global, but more phenomenological mass models. With the ab initio masses, the waiting point of the second $r$-process peak is strengthened, which leads to an overall slower nucleosynthesis flow, lower abundances of nuclei beyond the peak, and a stronger shift of the third $r$-process peak.

Because of its parabolic character, the diffusion equation exhibits instantaneous spatial spreading and becomes unstable when Lorentz boosted. According to the conventional interpretation, these features reflect a fundamental incompatibility with special relativity. In this Letter, we show that this interpretation is incorrect by demonstrating that any smooth and sufficiently localized solution of the diffusion equation is the particle density of an exact solution of the relativistic Vlasov-Fokker-Planck equation. This establishes the existence of a causal, stable, and thermodynamically consistent relativistic kinetic theory whose hydrodynamic sector is governed exactly by diffusion at all wavelengths. We further demonstrate that the standard arguments for instability arise from considering solutions that admit no counterpart in kinetic theory and that apparent violations of causality disappear once signals are defined in terms of the underlying microscopic data.

In relativity, relaxation processes are often assumed to undergo time dilation under Lorentz boosts. We show that this intuition fails generically. Because of relativity of simultaneity, Lorentz boosts can split a single relaxation mode into a continuum of excitations, with a width set by the maximal signal propagation speed. Focusing on linearized relativistic (kinetic or rheological) theories with an Onsager-type symmetry, we derive rigorous bounds on relaxation spectra in arbitrary inertial frames, expressed solely in terms of rest-frame spectral data at zero wave number. As a consequence, nonhydrodynamic gaps, maximal relaxation rates, and the convergence radii of hydrodynamic modes obey nontrivial Lorentz-covariant constraints. These results provide a unified framework for understanding how relativity constrains relaxation dynamics in many-body systems.

Recent models of the rapid proton ($rp$) capture process indicate that a competition between the ${}^{59}\mathrm{Cu}(p,\gamma ){}^{60}\mathrm{Zn}$ and ${}^{59}\mathrm{Cu}(p,\alpha ){}^{56}\mathrm{Ni}$ reactions may result in the formation of a nickel-copper (NiCu) cycle that traps the flux of material between ${}^{56}\mathrm{Ni}$ and ${}^{60}\mathrm{Zn}$. Here, we report the identification of 15 proton-unbound levels in ${}^{60}\mathrm{Zn}$, populated via ${}^{59}\mathrm{Cu}(d,n)$ transfer, which govern the rate of the ${}^{59}\mathrm{Cu}(p,\gamma ){}^{60}\mathrm{Zn}$ reaction in XRBs. Precise excitation energies for levels in ${}^{60}\mathrm{Zn}$ were obtained from observed $\gamma$ decays, and spectroscopic factors were determined from angle-integrated cross sections. Incorporating these results into stellar-model calculations, we find that with experimentally constrained uncertainties a NiCu cycle in XRBs is indeed possible, though we limit its branching strength to less than 38%. While modest, such a branching has significant impact on the light curve, motivating further studies of the relevant rates. Our calculations also indicate that a significant NiCu cycle leads to an increase in the amount of odd-$A$ nuclei in the burst ashes, which may affect Urca cooling processes in neutron star crusts.

The multifaceted decay properties of ${}^{116}\mathrm{Cs}$ near the proton drip line have been studied at ISOLDE, CERN. More than six new unbound states of ${}^{116}\mathrm{Xe}$ have been identified. A novel phenomenon of low energy isoscalar octupole resonance has been observed. After proton decay, that state populates both ${11/2}^{+}$ and ${11/2}^{-}$ states of ${}^{115}\mathrm{I}$. First observation of delayed two protons is reported in the medium heavy region and this exotic decay mode is 3 orders of magnitude lower than the delayed single proton events. The fingerprint of long-range proton-proton correlation has been evidenced in the relative momentum of two protons. An indication of rare event, heavy cluster emission (${}^{12}\mathrm{C}$) in medium heavy nucleus is reported.

The dipole response of ${}^{102}\mathrm{Ru}$ has been investigated for the first time using nuclear resonance fluorescence, providing comprehensive and detailed information about the nucleus. The $M1$ strength, concentrated in the 3–4 MeV region, is consistent with a scissors resonance. As a surprising new feature, a pronounced $E1$ resonancelike structure at 4.5–5.5 MeV has been found. It is interpreted as an octupole resonance and provides evidence for low-spin octupole correlations in this excitation energy regime. The experimental results are compared with quasiparticle random phase approximation calculations, which reproduce the gross features of the cumulative strength. These observations support the coexistence of $M1$ scissors and octupole-induced $E1$ resonances as a general feature of deformed nuclei with octupole softness.

Nuclear time-dependent density functional theory is used to investigate spin generation and entanglement of fission fragments in spontaneous fission of ${}^{252}\mathrm{Cf}$, incorporating both axial and nonaxial deformations. Axially symmetric fission trajectories enforce strict constraints: counterrotation (twisting mode) along the fission axis and equiprobable bending and wriggling modes perpendicular to it. Nonaxial modes broaden the distributions of fission fragment spin projection on the fission axis, and allow for axial (tilting) collective rotations, which are forbidden on axially symmetric trajectories. Mutual information analysis reveals that axial-symmetry breaking reduces spin-spin correlations along the fission axis of symmetric cases, while perpendicular correlations remain more resilient. The effect of triaxial degrees of freedom on the opening angle distribution between the spins of the fission fragments is analyzed.

The observation of active ${}^{44}\mathrm{Ti}$ in supernova remnants offers the potential to solve one of the most debated questions in modern astrophysics, the exact underlying explosion mechanism of core collapse supernovae (CCSNe). In particular, a comparison between the predicted synthesized yield of ${}^{44}\mathrm{Ti}$ and the ejected flux is expected to allow for a determination of the mass cut of the star. Unfortunately, such comparisons are currently severely hindered by large uncertainties in the nuclear reactions governing the production and destruction of ${}^{44}\mathrm{Ti}$. On this note, the astrophysical ${}^{45}\mathrm{V}(p,\gamma ){}^{46}\mathrm{Cr}$ reaction is expected to play a decisive role. We present the first experimental information on resonant states in the ${}^{45}\mathrm{V}(p,\gamma ){}^{46}\mathrm{Cr}$ reaction. Excitation energies have been measured with high precision for ten previously unknown, low-spin, proton-unbound states in ${}^{46}\mathrm{Cr}$, and spin-parity-assignment constraints have been made using observed $\gamma$-decay patterns and shell-model calculations. We find that an $\ell =1$ resonance at 714 keV dominates the ${}^{45}\mathrm{V}(p,\gamma ){}^{46}\mathrm{Cr}$ reaction for the entire temperature range of $\alpha$-rich freezeout. Moreover, the nominal rate is found to be $\sim 25–50\%$ of previous estimates for $T>1.2\mathrm{GK}$, indicating an increase in ${}^{44}\mathrm{Ti}$ production in CCSNe of $\sim 20–35\%$.

Precise experimental information on hyperon-nucleon interactions is scarce but of paramount importance to our understanding of the inner structure of compact stars. In this Letter, we report the first experimental results of correlation functions between deuterons ($d$) and $\mathrm{\Lambda }$ hyperons in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=3.0\mathrm{GeV}$ measured by the STAR experiment at the Relativistic Heavy Ion Collider. A clear enhancement at small relative momenta has been observed in the correlation function. Through a Bayesian inference analysis, the source size parameters as a function of collision centrality and the spin-dependent strong interaction parameters (scattering length $f_0$ and effective range $d_0$) are extracted using the Lednický-Lyuboshitz formalism. The derived doublet spin state parameters ($f_0$, $d_0$) lead to a novel method to precisely determine $\mathrm{\Lambda }$ separation energy for the weakly bounded hypertriton ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$.

We report the first evidence of spin interference in exclusive $J/\psi \to e^{+}{e}^{-}$ photoproduction in ultraperipheral heavy-ion collisions at STAR at $\sqrt{s_{NN}}=200\mathrm{GeV}$. In $\mathrm{Au}+\mathrm{Au}$ collisions, a negative $\cos (2\varphi )$ modulation is found for $p_T<120\mathrm{MeV}/c$ with a significance of $3.2\sigma$, while the isobar data ($\mathrm{Ru}+\mathrm{Ru}$, $\mathrm{Zr}+\text{Zr}$) show a consistent negative modulation with a significance of $1.9\sigma$, opposite in sign to that in ${\rho }^0\to {\pi }^{+}{\pi }^{-}$ photoproduction. This establishes for the first time that the interference sign is controlled by the spin structure of the final-state daughters, resolving the ambiguity present in the all-boson ${\rho }^0$ channel. The compact $J/\psi$ probes gluon distributions at perturbative scales, resulting in a weaker modulation and providing stringent constraints on color glass condensate calculations. These findings demonstrate that spin-dependent interference in heavy vector mesons provides a new, experimentally accessible handle on gluon structure beyond traditional cross-section measurements.

A century ago, Wigner’s SU(4) symmetry was introduced to explain the properties of atomic nuclei. Despite recent revived interest, its impact on nuclear structure, transitions, and reactions has not been fully explored. Here, we show that a variety of high-fidelity nuclear interactions predict nuclear states that have $\ge 90\%$ probability of being in a single SU(4) irreducible representation. Meanwhile, our analysis of axial current operators in chiral effective field theory ($\chi \mathrm{EFT}$) reveals that one-body currents at low momentum transfer act only within SU(4) irreducible representations, while two-body currents connect different representations. These selection rules interfere with the expected convergence pattern of the $\chi \mathrm{EFT}$ expansion and explain key phenomenological observations, e.g., the unnaturally large two-body corrections to the axial-current matrix elements in eight-body nuclei.

The trace anomaly of dense matter, $\mathrm{\Delta }\equiv 1/3-P/ϵ$, defined through the ratio $w\equiv P/ϵ$ of pressure $P$ to energy density $ϵ$, quantifies deviations from conformal symmetry and provides a dimensionless measure of the stiffness of the equation of state (EOS) relevant for both neutron stars and heavy-ion collisions. While $\mathrm{\Delta }(ϵ)$ has recently been inferred from neutron star observations, we report the first Bayesian extraction of the trace anomaly from collective flow observables in intermediate-energy heavy-ion collisions. By employing transport-model simulations that explicitly decouple the cold matter mean-field potential from thermal effects, we directly constrain the EOS of cold dense matter. Remarkably, the trace anomaly inferred from laboratory flow data agrees quantitatively, within 68% credible intervals, with independent astrophysical posterior bands. This nontrivial agreement demonstrates that heavy-ion collisions and neutron star observations probe the same macroscopic properties in a mutually consistent way, establishing the dense-matter trace anomaly as a composition-insensitive macroscopic bridge observable across widely different physical environments.

Heavy flavor production serves as an ideal probe of the hadronization mechanism of the quark-gluon plasma created in relativistic heavy ion collisions. We study charm-quark hadronization using Langevin transport in the medium together with a sequential coalescence model. Since $D_s$ forms earlier than $D^0$, as obtained from the Dirac equation with an in-medium potential extracted from lattice QCD, the $D_s$ elliptic flow $v_2$ is smaller than the $D^0$ $v_2$ in the intermediate-$p_T$ region, in good agreement with the recent ALICE data. Incorporating sequential coalescence, charm-quark number conservation, and strangeness enhancement predicts a peak in the yield ratio $D_s/D^0$ at low $p_T$, which can be tested in future heavy-ion collisions.