Using $(10087\pm 44)\times {10}^{6}J/\psi$ events collected with the BESIII detector, a full angular analysis is carried out on the process $J/\psi \to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\to n{\pi }^0\overline{p}{\pi }^{+}+\mathrm{c}.\mathrm{c}$. The decay parameters ${\alpha }_0$ for $\mathrm{\Lambda }\to n{\pi }^0$ and ${\overline{\alpha }}_0$ for $\overline{\mathrm{\Lambda }}\to \overline{n}{\pi }^0$ are measured to be $0.668\pm 0.007\pm 0.002$ and $-0.677\pm 0.007\pm 0.003$, respectively, yielding the most precise test for $CP$ symmetry of neutral decays of $\mathrm{\Lambda }$, $A_{CP}^0=({\alpha }_0+{\overline{\alpha }}_0)/({\alpha }_0-{\overline{\alpha }}_0)$, to be $-0.006\pm 0.007\pm 0.002$. The ratios ${\alpha }_0/{\alpha }_{-}$ and ${\overline{\alpha }}_0/{\alpha }_{+}$ are determined to be $0.884\pm 0.013\pm 0.006$ and $0.885\pm 0.013\pm 0.004$, where ${\alpha }_{-}$ and ${\alpha }_{+}$ are the decay parameters of $\mathrm{\Lambda }\to p{\pi }^{-}$ and $\overline{\mathrm{\Lambda }}\to \overline{p}{\pi }^{+}$, respectively. The ratios, found to be smaller than unity by more than $5\sigma$, confirm the presence of the $\mathrm{\Delta }I=3/2$ transition in the $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ decays, which is expected to improve the theoretical calculations for isospin amplitudes, and $A_{CP}$, in hyperon decays. In all results, the first and second uncertainties are statistical and systematic, respectively.

We compute for the first time the production rate for four jets in electron-positron annihilation at next-to-next-to-leading order. Our calculation exhibits the highest final-state jet multiplicity considered at this perturbative accuracy to date. The cancellation of infrared singularities is achieved in the antenna subtraction scheme, relying particularly on generalized antenna functions. The evaluation of the two-loop virtual corrections is enabled by the construction of a new basis of transcendental special functions tailored to four-particle decay kinematics. Our results are compared with LEP data, finding improved agreement with respect to the next-to-leading order calculation. In the region where perturbative predictions are most reliable, we observe a significant reduction of theory uncertainties, which now fall below the experimental ones.

Based on $334{\mathrm{pb}}^{-1}$ of photoproduction data collected with the GlueX detector at Jefferson Lab, we have measured for the first time the cross section of the exclusive reaction $\gamma +p\to \varphi (1020){\pi }^{+}{\pi }^{-}p$ by reconstructing the final state $K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}p$ produced with a photon beam of energies between 8.0 and 11.6 GeV. Based on the measured differential cross section, we have performed a search for the strangeoniumlike exotic candidate $Y(2175)$, recently renamed to $\varphi (2170)$. This state has been reported by different $e^{+}{e}^{-}$ annihilation experiments and it is addressed here for the first time in a photoproduction experiment. We do not find evidence for this state when using the resonance parameters quoted by the Particle Data Group and provide upper limits on the photoproduction cross section. Instead, we find a structure at a mass of $m(\varphi {\pi }^{+}{\pi }^{-})=2.24\mathrm{GeV}/c^2$ with a statistical significance of about $5\sigma$. The parameters of this structure differ from those quoted by the Particle Data Group for the $\varphi (2170)$ and are consistent with a previous observation in $e^{+}{e}^{-}$ annihilation. In addition, there is evidence for a second structure at $1.82\mathrm{GeV}/c^2$.

The production of identified hadrons inside jets in $e^{+}{e}^{-}$ annihilation allows for detailed studies of parton-to-hadron fragmentation functions in a clean environment. We compute hadron-in-jets production cross sections for $e^{+}{e}^{-}\to 2\text{jets}$ and $e^{+}{e}^{-}\to 3\text{jets}$ to next-to-next-to-leading order (NNLO) in perturbative QCD. By comparing with data from the ALEPH experiment, we demonstrate the implications of the newly computed theory predictions for precision phenomenology.

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 $\sim 20–35\%$.

We describe a spin interferometer using ultracold YbF molecules and develop the complete set of techniques needed to measure the electron’s electric dipole moment, $d_e$, with this apparatus. The molecules are cooled in an optical molasses and prepared in a single internal quantum state. A Raman transition prepares a spin superposition that evolves in parallel magnetic and electric fields before a second Raman transition maps the phase onto the populations of two hyperfine states. These populations are read out using detectors that have spatial and temporal resolution and approach unit efficiency. We characterize the efficiencies and fidelities of all these steps and evaluate the sensitivity of this approach to measuring $d_e$.

Turbulence enhances momentum transport in classical fluids, effectively increasing their viscosity. We investigate an analogous effect in a superfluid by measuring the damping of collective oscillations in an atomic Bose-Einstein condensate (BEC) containing stationary spin-superflow turbulence. Using continuous spin driving to maintain turbulence in a spin-1 ${}^{23}\mathrm{Na}$ BEC, we excite its quadrupole mode and measure the damping rate over a range of temperatures. The damping consistently exceeds the Landau-damping rate expected for an equilibrium, nonturbulent BEC. The enhancement likely originates from two complementary processes: direct energy transfer from the mode to turbulent condensate fluctuations and turbulence-induced modification of the thermal cloud that amplifies Landau damping. These results establish collective-mode damping as a sensitive probe of momentum transport in superfluid turbulence.

Optical crosstalk due to imperfect addressing in trapped-ion entangling gates generates unwanted nonlocal entanglement between target ions and their combined set of neighbors that is difficult to mitigate using standard quantum error correction. We present a method to design entangling operations that are inherently insensitive to crosstalk by engineering the effective qubit-qubit coupling matrix. By controlling the geometric phases generated in the motional modes of the ion string, we engineer a coupling matrix that selectively excludes coupling between target and neighbor ions from the entangling operation. This approach requires no knowledge of the amount of crosstalk present and avoids the need for additional gate operations or modifications to the optical setup. We numerically demonstrate the construction of crosstalk-insensitive entangling pulses for target ion pairs within an equispaced 20-ion string and provide experimental validation of coupling matrix engineering for crosstalk-insensitive entanglement in a 3-ion string.

On-chip generation of high-purity single photons is essential for scalable photonic quantum technologies. Spontaneous parametric down conversion (SPDC) is widely used to generate photon pairs for heralded single-photon sources, but intrinsic spectral correlations of the pairs often limit the purity and interference visibility of the heralded photons. Existing approaches to suppress these correlations rely on narrowband spectral filtering, which introduces loss, or exploiting different polarizations, which complicates on-chip integration. Here, we exploit higher-order spatial modes to enable spectrally separable photon-pair generation in thin-film lithium niobate nanophotonic circuits, with all interacting fields residing in the same polarization. Spectral separability is achieved by engineering group-velocity matching using higher-order transverse-electric modes, combined with a Gaussian-apodized poling profile to further suppress residual correlations inherent to standard periodic poling. Subsequent on-chip mode conversion with efficiency exceeding 95% maps the higher-order mode to the fundamental mode and routes the photons into distinct output channels. The resulting heralded photons exhibit spectral purities up to 94% inferred from joint-spectral intensity and 89% from unheralded $g^{(2)}$ measurement. This approach enables flexible spectral and temporal engineering of on-chip quantum light sources for quantum computing and quantum networking.

We study the half-filled Haldane-Holstein model, where a paradigmatic Chern insulator is coupled to fully dynamical phonons, and provide an unbiased characterization of how retarded electron-phonon interactions destabilize Chern topology. Using determinant quantum Monte Carlo, we find that increasing the coupling drives an abrupt, first-order transition from a Chern insulator to a staggered charge-density wave that acts as a dynamical sublattice (Semenoff) mass. The transition is simultaneously signaled by a nearly quantized many-body Bott index and a real-space local Chern marker constructed from the interacting Green’s function, both of which collapse as the charge order parameter becomes extensive. Spectral and open-boundary calculations reveal concomitant gap closing and the loss of boundary spectral weight at the critical coupling. Despite the generic phase problem induced by broken time-reversal symmetry, we show that it remains mild in the low-frequency regime and that the average phase factor sharply tracks the Chern insulator-charge density wave boundary. Our results establish a concrete route by which electron-phonon coupling can trigger a discontinuous collapse of Chern topology and provide experimentally relevant signatures for correlated topological platforms.

Correlated kagome metals host unique electronic states that enable exotic quantum phenomena. In the recently emerged ${\mathrm{CsCr}}_6{\mathrm{Sb}}_6$, these manifest through Kondo behavior from localized $\mathrm{Cr}\text{−}3d$ electrons and unprecedented band flattening near the Fermi level. Yet the intricate interplay among Kondo screening, magnetic frustration, and electronic correlations remains poorly understood—a fundamental gap we address through multifaceted experimental and theoretical approaches. Our angle-resolved photoemission spectroscopy measurements reveal electronic correlation-renormalized flat bands, and our muon spin relaxation study detects short-range magnetic order at $T_{\mathrm{N}}\sim 80\mathrm{K}$. Complementing these findings, density-functional theory and dynamical mean-field theory calculations identify a coherent-incoherent crossover at $T_{\mathrm{N}}$, with a remarkable restoration of coherence accompanying local moment suppression—an anomalous hallmark of Kondo behavior. Intriguingly, despite strong interlayer antiferromagnetic coupling, the system evades long-range magnetic order due to competing magnetic configurations separated by sub-meV energy differences. These insights establish ${\mathrm{CsCr}}_6{\mathrm{Sb}}_6$ as a prototypical platform for investigating dynamical Kondo screening in correlated flat-band systems, opening new avenues to study flat-band physics and frustrated magnetism in correlated kagome lattices.

The hallmark of Chern insulators is the unidirectional propagation of chiral edge states, which are immune to imperfections due to bulk topological protection. However, this robustness presents a fundamental challenge in pausing or spatially confining these information carriers on demand. Here, we propose a topological slot that enables spatial trapping and controlled release of these chiral modes. The trapping occurs at the interface between two topological domains that share the same Chern number but exhibit a polarization mismatch. We implement the topological slot in phononic crystals and directly observe acoustic waves that propagate or become trapped under different slot configurations. The proposed topological slot provides a new route to manipulating topological states and may provide a pathway toward topological information storage and encoding.

Non-Abelian topological insulators, arising from a non-Abelian gauge field, not only link to particle physics and the strong and weak forces of nature, but also create coveted topological phenomena with remarkable properties. Although significant efforts have been made to develop artificial non-Abelian gauge fields, few of them applied to momentum space to realize non-Abelian topological insulators. Here, we propose a scheme to create artificial SU(2) gauge fields in phononic crystals. By implementing this scheme to a non-Abelian Hofstadter model, we overcome the challenge of constructing an analog of the non-Abelian magnetic field in momentum space that opens nontrivial band gaps. We experimentally realize and observe such a non-Abelian topological insulating phase in a phononic crystal. Furthermore, we experimentally investigate the spin rotation and flipping phenomena of non-Abelian topological boundary states along a specific plane of the Bloch sphere, which are linked to the signatures of the underlying non-Abelian gauge field. Our Letter not only opens the door to the realization and characterization of non-Abelian topological insulators, but also provides a reconfigurable platform for exploring non-Abelian physics in a classical system.

The van der Waals room-temperature ferromagnet ${\mathrm{Fe}}_5{\mathrm{GeTe}}_2$ has garnered considerable research interest due to its intriguing magnetic and transport properties, as well as its potential applications, yet their microscopic origin remains unclear. Using angle-resolved photoemission spectroscopy and density functional theory calculations, we resolve an electronic structure corresponding to the up-up-up-type configuration. Pronounced Fermi surface reconstruction and a 25 meV dispersion kink referring to the strong electron-magnon coupling have been observed near $T_1\sim 105\mathrm{K}$, coincident with anomalies in resistivity and magnetic susceptibility. Our calculations identify the emergence of Fe(1) sublattice spin order as the driving force behind both phenomena. These findings reveal the decisive role of sublattice-dependent magnetism in governing the coupled electronic and magnetic properties of ${\mathrm{Fe}}_5{\mathrm{GeTe}}_2$, establishing sublattice engineering as a pathway for tuning correlated behavior in two-dimensional magnets.

The identification of fractionalized excitations in quantum spin liquids (QSLs) remains a central challenge in condensed matter physics. In dipolar-octupolar (DO) pyrochlores, such as ${\mathrm{Ce}}_2{\mathrm{Zr}}_2{\mathrm{O}}_7$, the candidate $\pi$-flux quantum spin ice (QSI) state is predicted to host both gapless emergent photons and a continuum of spinons. However, resolving these modes at zero field is complicated by their spectral overlap and the presence of nonmagnetic scattering near zero energy. Here, we report neutron scattering experiments on ${\mathrm{Ce}}_2{\mathrm{Zr}}_2{\mathrm{O}}_7$ under a magnetic field along the [1, 1, 1] direction. In contrast to previous unpolarized studies at zero field that relied on high-temperature subtraction, we use a same-temperature high-field subtraction protocol to isolate the photon and spinon modes. Leveraging the selective coupling of the magnetic field to the dipolar degrees of freedom, we demonstrate the spectroscopic demarcation of these excitations. We observe that weak fields ($\approx 0.15\mathrm{T}$) suppress the low-energy photon weight while leaving the high-energy spinon continuum robust, albeit hardened. Our results, supported by gauge mean-field theory and exact diagonalization calculations, provide strong evidence for the $\pi$-flux QSI state and introduce a powerful field-tuning protocol for investigating DO-QSLs.

Altermagnetic order, characterized by the Néel vector, breaks time-reversal symmetry (TRS) even in the nonrelativistic limit. Although spin-polarized and anomalous transport phenomena emerge with this order, they are mutually compensated by TRS-connected antiphase domains with opposite Néel vectors. Here we employ polarized neutron diffraction to directly probe the altermagnetic order in MnTe. Pronounced nuclear-magnetic interference terms were observed, providing direct evidence of a net Néel vector in the bulk crystal. Moreover, a weak ferromagnetic moment (WFM), originating from relativistic spin-orbit coupling, was found to be coupled with the altermagnetic order. Both the altermagnetic order and the WFM can be switched by milli-Tesla-scale magnetic field cooling.

Strongly coupled light-matter exciton-polaritons constitute an on-chip solid-state platform where the macroscopic quantum phenomenon of condensation is not only achievable at elevated temperatures, but can also be optically controlled, including through their interaction with inaccessible “dark” states. A recent study has shown that polariton condensation can be established under nonlinear two-photon pumping, paving the way toward dark-state–condensate coherent control and highly efficient terahertz (THz) lasing. In this Letter, we show for the first time a temporal signature of dark exciton-induced bosonic stimulation by investigating one- and two-photon-pumped condensation with time-resolved photoluminescence spectroscopy. Our results show a clear difference in the detuning dependence of the buildup and relaxation rates of the condensate-induced blueshifts under one- and two-photon pumping. This difference is associated with the stronger exciton-fraction dependence expected for one-photon-pumped condensation, where polariton-polariton stimulation dominates, compared with two-photon-pumped condensation, where a 2p-exciton-to-lower-polariton THz transition can provide another stimulation channel, together with various spin-flip, electron-hole exchange, and phonon-based mechanisms. These observations indicate the presence of a new dark-state–originated stimulation channel that could facilitate highly-efficient THz lasing in semiconductor microcavities.