We conduct an indirect dark matter (DM) search in the vicinity of the Galactic Center, focusing on a square region within $\pm 9°$ in Galactic longitude and latutide, using 2865 days of data ($\sim 8\mathrm{yr}$) from the High-Altitude Water Cherenkov (HAWC) Observatory. We explore DM particles within the weakly interacting massive particles framework with masses from 1 TeV to 10 PeV. Analyzing three annihilation channels ($b\overline{b}$, ${\tau }^{+}{\tau }^{-}$, $W^{+}{W}^{-}$) and three density profiles (Navarro-Frenk-White, Einasto, Burkert), we find no significant excess and set 95% CL upper limits on the velocity-weighted annihilation cross section. Our results provide the first constraints on DM particles well above 100 TeV using gamma-ray data from the vicinity of the Galactic Center, with the strongest limits $\mathcal{O}({10}^{-24}){\mathrm{cm}}^3/\mathrm{s}$, from the ${\tau }^{+}{\tau }^{-}$ channel and the Einasto profile.

We perform the first high-throughput search and evaluation of materials that can serve as excellent low-mass dark matter detectors. Using properties of close to 1000 materials from the Materials Project database, we project the sensitivity in dark matter parameter space for experiments constructed from each material, including both absorption and scattering processes between dark matter and electrons. Using the anisotropic materials in the dataset, we further compute the level of daily modulation in interaction rates and the resulting directional sensitivities, highlighting materials with prospects to detect the dark matter wind. Our methods provide the basic tools for the data-driven design of dark matter detectors, and our findings lay the groundwork for the next generation of highly optimized direct searches for dark matter as light as the keV scale. This represents a major step in the application of results from condensed matter physics to dark matter search design.

By leveraging a recently developed slippage-compensation scheme in externally seeded free-electron lasers (FELs), we propose a method for generating few-femtosecond extreme-ultraviolet (XUV) pulse pairs with tunable topological properties and adjustable temporal delay. Simulations show that the topological charge $l$ of each pulse can be independently set to $l=-1$, 0, 1, while the delay between the pulses can be tuned from a few to several tens of femtoseconds. Compared with superradiance—the only other currently viable approach for producing XUV pulse pairs with these characteristics—the proposed scheme offers greater flexibility, as it does not require driving the FEL into saturation, which typically necessitates a cascade configuration. Furthermore, when combined with pulse-to-pulse polarization switching, this approach has the potential to extend XUV studies of circular and helical dichroism in chiral systems and magnetic materials, as well as high-resolution imaging, into the few-femtosecond regime.

We derive exact analytical expressions for higher-order correlations of Gaussian level-set interfaces, establishing a direct link between bulk field statistics and interface geometry. This framework enables efficient reconstruction of disordered media, detailed modeling of Gaussian foams—structured, double-thresholded interfaces with tunable morphology—and analysis of memory-enhanced anisotropy reflecting directional persistence in the surface structure. These results open new possibilities for characterizing complex transport, guiding stochastic reconstructions, designing materials with desired properties, quantifying the information content of correlation functions, and modeling directional processes on irregular boundaries.

We establish a set of exact sum rules that relate the interatomic force constants to the frequency-dependent electromagnetic susceptibility of a solid or molecule, thereby generalizing the long-established principles of rototranslational symmetry to the nonadiabatic regime. Crucially, we show that in practical numerical implementations, these sum rules are violated unless special precautions are taken in the treatment of the atomic pseudopotentials. We solve these issues once and for all by correctly adapting the pseudopotential to the motion of the corresponding nucleus with a velocity dependence of the nonlocal operator. This prescription restores the correct Galilean covariance of the Schrödinger equation and the expected identity between mechanical rototranslations and electromagnetic perturbations. These results conclusively fix a number of worrisome inconsistencies that were pointed out over the years in the context of linear-response theory, restoring, e.g., the validity of the Larmor theorem and the equivalence between the inertial and electrical definitions of the Drude weight in metals.

We report the observation of an emergent charge order mode in the optically excited cuprate ladder ${\mathrm{Sr}}_{14}{\mathrm{Cu}}_{24}{\mathrm{O}}_{41}$. Near-infrared light in the ladder plane drives a symmetry-protected electronic metastable state together with a partial melting of the equilibrium charge order. Our time-resolved resonant inelastic x-ray scattering measurements at the upper Hubbard band reveal a collective excitation dispersing from the charge order wave vector up to 0.8 eV with a slope on the order of the quasiparticle velocity. These findings reveal a regime where correlated carriers acquire itinerant character at finite momentum, and charge order becomes dynamically fluctuating, offering a platform to explore light-induced pairing instabilities.

Measuring universal data in the strongly correlated regime of quantum critical points remains a fundamental objective for quantum simulators. In foundational work, Calabrese and Cardy demonstrated how these data govern the dynamics of certain global quenches to $1+1$-dimensional conformal field theories. While the quasiparticle picture they introduce has been widely successful in both theory and experiment, their seminal prediction that the critical exponents are simply encoded in the relaxation rates of local observables is challenging to investigate experimentally. In this Letter, we examine the critical quench dynamics of local observables from two types of readily accessible initial conditions: ground states and finite-temperature ensembles. We identify universal scaling collapses and scaling functions, utilizing a combination of conformal perturbation theory and tensor network numerics. For the finite-temperature quenches, we determine a regime in which the conformal field theory results are recovered, thereby allowing universal quantum critical data to be extracted from realistic quenches.

A search for pairs of light neutral pseudoscalar bosons ($A$) resulting from the decay of a Higgs boson is performed. The search is conducted using LHC proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$, collected with the CMS detector in 2016–2018 and corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$. The $A$ boson decays into a highly collimated electron-positron pair. A novel multivariate algorithm using tracks and calorimeter information is developed to identify these distinctive signatures, and events are selected with two such merged electron-positron pairs. No significant excess above the standard model background predictions is observed. Upper limits on the branching fraction for $H\to AA\to 4e$ are set at 95% confidence level, for masses between 10 and 100 MeV and proper decay lengths below $100\mathrm{\mu }\mathrm{m}$, reaching branching fraction sensitivities as low as ${10}^{-5}$. This is the first search for Higgs boson decays to four electrons via light pseudoscalars at the LHC. It significantly improves the experimental sensitivity to axionlike particles with masses below 100 MeV .

Rotation is a natural tool in ultracold gases to break time-reversal symmetry, yet its impact on the collective excitations of supersolids remains largely unexplored. We show theoretically that tuning the rotation frequency, rather than the interparticle interactions, can trigger the superfluid-to-supersolid transition in Bose-Einstein condensates. Computing excitation spectra in the presence of vortices and persistent currents, we uncover a vortex-driven desoftening mechanism whereby quantized vorticity elevates the gapless Goldstone mode to a finite-energy roton, restoring superfluidity. This effect results in reentrant supersolid phases as a function of rotation frequency, revealing a fundamental coupling between topological defects and crystalline order.

We demonstrate that nondiffusive, fluidlike heat transport, such as heat backflowing from cooler to warmer regions, can be induced, controlled, and amplified in extreme thermal conductors such as graphite and hexagonal boron nitride. We employ the viscous heat equations, i.e., the thermal counterpart of the Navier-Stokes equations in the laminar regime, to show with first-principles quantitative accuracy that a finite thermal viscosity yields steady-state heat vortices, and governs the magnitude of transient temperature waves. Finally, we devise strategies that exploit devices’ boundaries and resonance to amplify and control heat hydrodynamics, paving the way for novel experiments and applications in next-generation electronic and phononic technologies.

The sign problem is one of the central obstacles to efficiently simulating quantum many-body systems. It is commonly believed that some phases of matter, such as the double semion model, have an intrinsic sign problem and can never be realized in a local sign problem-free Hamiltonian due to the nonpositivity of the wave function. We show that this is not the case. Despite not being stoquastic, the standard criteria for the existence of a sign problem, the double semion model, and all twisted quantum double phases of matter for finite groups $\mathcal{G}$ can be realized in local Hamiltonians that are sign problem-free within a stochastic series expansion. The lack of a sign problem is not fine-tuned and does not require the Hamiltonian to be exactly solvable, with sign problem-free perturbations allowing access to a variety of topological phase transitions.

The optical excitation of a bright exciton may be followed by the formation of lower-energy dark states. In these formation and relaxation processes, nonequilibrium exciton and phonon populations play a dominant role but remain so far largely unexplored, as most states are inaccessible by regular spectroscopies. Here, on the example of homobilayer $2\mathrm{H}\text{−}{\mathrm{MoS}}_2$, we realize direct access to the full exciton relaxation cascade from experiment and theory. We find distinct changes in the time-, energy-, and in-plane momentum-resolved photoemission spectral function that can be explained only when considering the formation and subsequent thermalization of excitonic nonequilibrium occupation distributions. In agreement with microscopic many-particle calculations, we quantify the timescales for the formation of a nonequilibrium dark-excitonic occupation and its subsequent thermalization to 85 and 150 fs, respectively. Our results provide a previously inaccessible view of the complete exciton relaxation cascade, which is of importance for the future characterization of nonequilibrium excitonic phases and the efficient design of optoelectronic devices.

The catalytic extension of a discrete two-stroke engine employs a cyclic auxiliary system that remains thermally decoupled and performs no work, yet enhances power and efficiency beyond its noncatalytic counterpart. While discrete models are analytically tractable, they remain experimentally challenging due to the precise control required over individual strokes. Continuous engines, simultaneously coupled to heat baths and a driving field, offer a more experimentally feasible alternative. Here, we establish a unified framework connecting discrete and continuous machines—with and without a catalyst—by mapping unitary strokes and thermalization steps onto an interaction Hamiltonian and Markovian dissipation. Replacing probability flows with probability currents yields a continuous analog of catalytic Otto-like schemes. Focusing on the simplest catalytic extension, we demonstrate that catalytic enhancement persists in the continuous regime. Our results demonstrate how discrete models offer valuable insights for analyzing the performance of continuous thermal machines.

We investigate the propagation of ultraheavy (UH) nuclei as ultrahigh-energy cosmic rays (UHECRs). We show that their energy loss lengths at $\lesssim 300\mathrm{EeV}$ are significantly longer than those of protons and intermediate-mass nuclei, and that the highest-energy cosmic rays with energies beyond $\sim 100\mathrm{EeV}$, including the Amaterasu particle, may be UH-UHECRs. For the first time, we derive constraints on the contribution of UH-UHECR sources, and find that the current data are consistent with energy generation rate densities of UHECRs from collapsars and neutron star mergers. Our model predicts that the mean value of the depth of shower maximum is lower than that for iron nuclei beyond 100 EeV, which can be tested with future composition measurements, e.g., AugerPrime and the Global Cosmic Ray Observatory. In addition, the spectral tension between the Telescope Array (TA) and the Pierre Auger Observatory can be alleviated by considering the enhanced contribution of UHECRs—including UH nuclei—from a nearby transient.

We consider matrix quantum mechanics with multiple bosonic matrices, including those obtained from dimensional reduction of Yang-Mills theories. Using the matrix bootstrap, we study simple observables like $⟨\mathrm{tr}{X}^2⟩$ in the confining phase of the theory in the infinite $N$ limit. Exploiting the symmetries of these models and applying nonlinear relaxation, we impose constraints that include traces of words of length up to 14. Our results yield rigorous bounds on the large-$N$ ground-state dynamics, along with estimates of selected low-order observables to eight significant digits.

We present an inclusive search for anomalous production of single-photon events from neutrino interactions in the MicroBooNE experiment. The search and its signal definition are motivated by the previous observation of a low-energy excess of electromagnetic shower events from the MiniBooNE experiment. We use the Wire-Cell reconstruction framework to select a sample of inclusive single-photon final-state interactions with a final efficiency and purity of 7.0% and 40.2%, respectively. We leverage simultaneous measurements of sidebands of charged current ${\nu }_{\mu }$ interactions and neutral current interactions producing ${\pi }^0$ mesons to constrain signal and background predictions and reduce uncertainties. We perform a blind analysis using a dataset collected from February 2016 to July 2018, corresponding to an exposure of $6.34\times {10}^{20}$ protons on target from the Booster Neutrino Beam at Fermilab. In the full signal region, we observe agreement between the data and the prediction, with a goodness-of-fit $p$ value of 0.11. We then isolate a subsample of these events containing no visible protons, and observe $93\pm 22(\mathrm{stat})\pm 35(\mathrm{syst})$ data events above prediction, corresponding to just above $2\sigma$ local significance, concentrated at shower energies below 600 MeV.