Hard-scattered partons ejected from high-energy proton-proton collisions undergo parton shower and hadronization, resulting in collimated collections of particles that are clustered into jets. A substructure observable that highlights the transition between the perturbative and nonperturbative regimes of jet evolution in terms of the angle between two particles is the two-point energy correlator (EEC). In this Letter, the first measurement of the EEC at RHIC is presented, using data taken from 200 GeV $p+p$ collisions by the STAR experiment. The EEC is measured both for all the pairs of particles in jets and separately for pairs with like and opposite electric charges. These measurements demonstrate that the transition between perturbative and nonperturbative effects occurs within an angular region that is consistent with expectations of a universal hadronization regime that scales with jet momentum for a given initiator flavor. Additionally, a deviation from Monte Carlo predictions at small angles in the charge-selected sample could result from mechanics of hadronization not fully captured by current models.

With Bayesian inference, we investigate the impact of recent near-threshold $J/\psi$ production measurements by the $J/\psi 007$ experiment and GlueX Collaboration on the extraction of proton gravitational form factors. We apply the generalized parton distribution framework at the next to leading order and demonstrate a stable expansion for the near-threshold kinematics. We find that the experimental constraints are in good agreement with the state-of-the-art lattice simulations, where negative $C_q(t)$ and $C_g(t)$ are strongly preferred. This highlights a great potential to extract them from future high-precision experiments.

Analysis of neutron-capture cross sections in the resolved resonance range reveals that a large fraction of them (13 of 21, or 62%) exhibit highly significant ($>99.9\%$ confidence level) oscillations about their average value. Oscillations exceed a significance level of $5\sigma$ in nine cases (43%). Oscillations comprise $10.86\pm 0.64\%$ of the average cross section with periods ranging from 68.2 to 2380 eV. This contradicts random matrix theory (RMT), which predicts that fluctuations about the average cross section should be entirely random and demonstrates that deviations from RMT are common and widespread in neutron-capture data. These facts suggest there is a widespread physical mechanism that is missing from current nuclear physics models describing neutron-capture cross sections.

We investigate the residual energy distribution in the electron capture (EC) process of ${}^{159}\mathrm{Dy}$, emphasizing the role of subthreshold atomic states, which have typically been omitted in conventional spectral analyses. By incorporating these energetically forbidden hole states into the spectral function $P(E)$, we demonstrate a significant enhancement—over an order of magnitude—in the EC rate near the zero-momentum neutrino emission region. This enhancement increases further with larger $Q$ values, contrary to standard expectations. Our analysis shows that $P(E)$ can be experimentally determined, resolving ambiguities near the end point and enabling new approaches to “ultralow $Q$ value” EC reactions for neutrino mass studies.

A low-energy storage ring with an ultracold electron cooler has been coupled with a heavy-ion accelerator facilitating high-resolution electron-ion collision spectroscopy of the heaviest few-electron ions. In the present Letter resonant electron-ion recombination of berylliumlike ${\mathrm{Pb}}^{78+}$ ions was measured in the collision-energy range 9.3–16.5 eV and a value of 244.937(30) eV is derived for the ${\mathrm{Pb}}^{78+}(2s^2{{}^{1}S}_0-2s2p{{}^{3}P}_1)$ excitation energy. This result agrees with the most recent (less accurate) theoretical value of 244.942(52) eV [Malyshev et al., Phys. Rev. A 110, 062824 (2024)], which has been calculated by applying strong-field QED rigorously up to the second order. The present investigation suggests that further technical improvements can potentially increase the experimental accuracy by an order of magnitude.

After core ionization of ${\mathrm{CO}}_2$, typically an Auger-Meitner decay takes place, leading to the formation of a dicationic molecule that may dissociate into ${\mathrm{CO}}^{+}$ and ${\mathrm{O}}^{+}$. We demonstrate experimentally that the recoil momentum of the photoelectron determines which of the two equivalent bonds breaks during dissociation. At 20 keV photon energy, we observe an asymmetry of up to 25% for bond cleavage that depends on the emission direction of the photoelectron. Furthermore, we show that this effect leads to a significant nondipole effect in molecular dissociation in the laboratory frame: ${\mathrm{O}}^{+}$ fragments are more likely to be emitted in the direction opposite to the light propagation than along it.

Ultrashort laser pulses carrying orbital angular momentum (OAM) have become essential tools in atomic, molecular, and optical studies, particularly for investigating strong-field light-matter interactions. However, controlling and generating ultrashort vortex pulses presents significant challenges, since their broad spectral content complicates manipulation with conventional optical elements, while the high peak power inherent in short-duration pulses risks damaging optical components. To address these challenges, we demonstrate a “molecular wave plate” as a promising way for generating and controlling broadband ultrashort vortex beams. By exploiting the nonadiabatic alignment of linear gas-phase molecules induced by vector beams, the interaction between the vector beam and the gas-phase molecules results in spatially varying polarizability, imparting a phase modulation to a probe laser. This process effectively creates a tunable molecular wave plate that adapts naturally to a broad spectral range. By leveraging this approach, we can generate ultrashort vortex pulses across a wide range of wavelengths. Under optimized gas pressure and interaction length conditions, this method allows for highly efficient, near unity, conversion of circularly polarized light into the desired OAM pulse, thus enabling the generation of few-cycle, high-intensity vortex beams. This molecular wave plate, which overcomes the limitations imposed by conventional optical elements, opens up new possibilities for exploring strong-field physics, ultrafast science, and other applications that require high-intensity vortex beams.

Modulational instability (MI) is a fundamental phenomenon in the study of nonlinear dynamics, spanning diverse areas such as shallow water waves, optics, and ultracold atomic gases. In particular, the nonlinear stage of MI has recently been a topic of intense exploration and has been shown to manifest, in many cases, in the generation of dispersive shock waves (DSWs). In this Letter, we experimentally probe the MI dynamics in an immiscible two-component ultracold atomic gas with exclusively repulsive interactions, catalyzed by a hard-wall-like boundary produced by a repulsive optical barrier. We analytically describe the expansion rate of the DSWs in this system, generalized to arbitrary intercomponent interaction strengths and species ratios. We observe excellent agreement among the analytical results, an effective 1D numerical model, full 3D numerical simulations, and experimental data. Additionally, we extend this scenario to the interaction between two counterpropagating DSWs, which leads to the production of Peregrine soliton structures. These results further demonstrate the versatility of atomic platforms toward the controlled realization of DSWs and rogue waves.

We experimentally and theoretically study collective emission of a dense atomic ensemble coupled to a single mode in a nanophotonic microring resonator. Because many cold atoms are localized in a small volume, these trapped atoms collectively couple not only to the guided resonator mode but also to the nonguided modes in free space. Through tuning the atom-photon coupling and by adjusting the number of trapped atoms, we demonstrate superradiant emission to the microring resonator. For photon emission via the nonguided modes, our study reveals signatures of subradiance and superradiance when the system is driven to the steady state and to the timed-Dicke state, respectively. Our experimental platform thus presents the first atom-light interface with selective collective emission behavior into a guided mode and the environment. Our observation and methodology could shed light on future explorations of collective emission with densely packed quantum emitters coupled to nanophotonic light-matter interfaces.

Previous work showed that thermal light with a blackbody spectrum cannot be decomposed into a mixture of independent localized pulses. However, we find that in the weak-source limit and under the assumption of a flat spectrum, the first nonvacuum term in the state expansion does form a mixture of such pulses. This decomposition is essential for quantum-enhanced astronomical interferometry, which typically operates on localized pulses even though stellar light is inherently continuous-wave. We present a quantum derivation of the van Cittert–Zernike theorem that incorporates finite bandwidth, thereby justifying the operations on localized pulses while processing continuous-wave thermal light. For general spectra in the weak-source limit, we establish a criterion under which correlations between pulses can be safely neglected. When this criterion is not met, we provide a corrected strategy that accurately accounts for both the spectral profile and the detector-defined pulse shape.

The discovery of superconducting states in multilayer rhombohedral graphene with spin and valley polarization [1] has raised an interesting question: how does superconductivity cope with time-reversal symmetry breaking? In this Letter, using Ginzburg-Landau theory and microscopic calculation, we predict the existence of a new superconducting state at low electron density, which exhibits a spontaneously formed lattice of vortices and antivortices hosting Majorana zero modes in their cores. We further identify this vortex-antivortex lattice state in the experimental phase diagram and describe its experimental manifestations.

In electride liquids, electrons detach from atomic orbitals and freely occupy the interstitial regions, forming quasiatomic electrons. Here, using dense electride potassium liquid as an example, we uncover a fast crystallization behavior at ultralow temperatures. By combining machine-learned molecular dynamic simulations and ab initio calculations, we demonstrate that this rapid crystallization is attributed to quasiatomic electron flexibility, i.e., self-accommodation of atom size with the help of the change of quasiatomic electrons, particularly the population of involved quasiatomic electrons that is enhanced at low temperatures. This effect not only accelerates atomic mobility but also softens the stiffness of the solid-liquid interface, triggering supercollective atomic motion and enabling rapid crystallization. Our findings challenge conventional views of crystallization kinetics and reveal a previously unrecognized mechanism where electronic contributions play a dominant role in dictating metallic solidification.

We propose the dynamical Casimir effect in a time-modulated near-field system at finite temperatures. The system consists of two bodies made of polaritonic materials that are brought in close proximity to each other, and the modulation frequency is approximately twice the relevant resonance frequencies of the system. We develop a rigorous fluctuational electrodynamics formalism to explore the produced Casimir flux, associated with the degenerate as well as the nondegenerate two-polariton emission processes. We have identified flux contributions from both quantum and thermal fluctuations at finite temperatures, with a dominant quantum contribution even at room temperature under the presence of a strong near-field effect. We have found that the Casimir flux can be generated with a smaller modulation frequency through the higher-order dynamical Casimir effect. We have conducted a nonclassicality test for the total radiative flux at finite temperatures, and we have shown that nonclassical states of emitted photons can be obtained for a high temperature up to $\sim 250\mathrm{K}$. Our findings open an avenue for the exploration of the dynamical Casimir effect beyond cryogenic temperatures, and may be useful for creating tunable nanoscale nonclassical thermal states.

I formulate a theory of the inverse Faraday effect in an impure two-dimensional metallic system with lifted spin degeneracy induced by Rashba spin-orbit coupling. Using the formalism of nonequilibrium quantum field theory, the static contributions to the current density up to the second order in powers of the external electromagnetic field are evaluated. For circularly polarized light one of the contributions describes the emergence of static magnetization. It is shown that the direction of induced magnetization may change depending on the frequency of the external radiation and disorder scattering rate. I also find that at large frequencies the leading contribution to the induced magnetization is proportional to the square of the spin-orbit interaction and is inversely proportional to the fifth power of the frequency of an external electromagnetic wave.

The classic lattice XY model is one of the universal models of statistical mechanics appearing in a broad variety of optical and condensed matter systems. One of its possible realizations is a system of tunnel-coupled spinor polariton condensates, where phases of individual condensates play a role of the two- dimensional spins. We show that the account of the polarization degree of freedom of cavity polaritons adds a new twist to the problem, modifying in particular the structure of the ground state. We formulate the corresponding classical spin Hamiltonian, which couples phase and polarization dynamics, and consider several particular geometries, demonstrating the principal differences between the scalar and spinor cases. Possible analog of spin Meissner effect for coupled condensates is discussed.

This Letter used speckle visibility spectroscopy to probe velocity fluctuations in three-dimensional granular heap flow. The mean velocity profile comprises a fast-flowing surface layer over a creeping layer. In both layers, velocity fluctuations are scale invariant and self-similar, and the velocity spectra demonstrate power-law scaling, $E(f)\propto f^{\alpha }$. In the surface layer, $\alpha$ is between $-1.0$ and $-0.8$, consistent with Hwa and Kardar’s “running” sandpile model, indicative of a dynamically self-organized critical state. In the creep layer, $\alpha$ decreases with depth, reaching $\approx -1.5$ at a sufficiently deep layer; its theoretical basis remains unclear. Analysis of the fluctuation velocity distributions provides further insight into the microscopic origins of the spectrum. These findings may help resolve the long-standing puzzle of flow localization in gravity-driven granular flows, despite a uniform shear stress-to-pressure ratio.

We describe channel flows in a continuum model of deformable nematic particles. In a simple shear flow, deformability leads to a nonlinear coupling of strain rate and vorticity, and results in shape oscillations or flow alignment. The final steady state can depend on initial conditions, and we explain this behavior by considering a phase space representation of the dynamics. In Poiseuille flow, particle deformability and nematic elasticity induce banding, where particles near the walls are aligned, and those near the center of the channel oscillate in direction and shape. Our results show that particle deformability can lead to complex behavior even in simple flows, suggesting new microfluidic experiments.

Resonant axion-plasmon conversion in the magnetospheres of magnetars may substantially impact the landscape of dark-matter axion detection. This Letter explores how resonant axion-plasmon conversion modify the expected radio signals from axion-photon conversions observed on Earth. Critically, the resonant conversion radius lies within the region expected for axion-photon conversion, introducing a nonradiative power loss that diminishes the anticipated photon flux. Our analysis demonstrates that this effect can reduce radio telescope sensitivities, shifting them into regions excluded by previous experiments. These findings compel a reassessment of experimental constraints derived from radio signatures of axion-photon conversions and highlight the necessity of accounting for plasmon effects in astrophysical axion searches. The presented corrections provide critical insights for refining the detection strategies of future telescope-based dark matter axion experiments.