We study future lepton collider prospects for testing predictive models of leptophilic dark matter (DM) candidates with a thermal origin. We calculate experimental milestones for testing the parameter space compatible with freeze-out and the associated collider signals at past, present, and future facilities. This analysis places new limits on such models by leveraging the utility of lepton colliders. At $e^{+}{e}^{-}$ machines, we make projections using precision $Z$-pole observables from $e^{+}{e}^{-}\to {\ell }^{+}{\ell }^{-}+\cancel{E}$ signatures at large electron-positron collider and future projections for future circular collider (ee) in these channels. Additionally, a muon collider could also probe new thermal relic parameter space in this scenario via ${\mu }^{+}{\mu }^{-}\to X+\cancel{E}$, where $X$ is any easily identifiable standard model object. Collectively, these processes can probe much of the parameter space for which DM direct annihilation to ${\ell }^{+}{\ell }^{-}$ yields the observed relic density in Higgs-like models with mass-proportional couplings to charged leptons.

We investigate the Lieb-Liniger model of one-dimensional bosons subjected to periodic kicks. In both the noninteracting and strongly interacting limits, the system undergoes dynamical localization, leading to energy saturation at long times. However, for finite interactions, we reveal an interaction-driven transition from an insulating to a metallic phase at a critical kicking strength, provided the number of particles is three or more. Using the Bethe ansatz solution of the Lieb-Liniger gas, we establish a formal correspondence between its dynamical evolution and an Anderson model in $N$ spatial dimensions, where $N$ is the number of particles. This theoretical prediction is supported by extensive numerical simulations for three particles, complemented by finite-time scaling analysis, demonstrating that this transition belongs to the orthogonal Anderson universality class.

A novel technique for measuring plasma conditions using monochromatic pump-broadband-probe laser interactions has been experimentally demonstrated. Originally proposed in Ludwig et al. [Phys. Plasmas 26, 113108 (2019)], this method utilizes crossed-beam energy transfer between the broadband probe and the pump, mediated by plasma ion acoustic waves. The complete energy transfer spectrum can be captured in a single shot, enabling the inference of plasma parameters such as density, electron and ion temperatures, and flow velocity. Compared to Thomson scattering, this technique offers signal enhancements typically larger than 9 orders of magnitude, significantly reducing the required probe laser intensity and facilitating interactions that are linear and measurements that are nonperturbative of the plasma. Furthermore, it provides a powerful tool for advancing studies of crossed-beam energy transfer under conditions relevant to inertial confinement fusion experiments.

We develop a variational perturbation expansion around dynamical mean-field theory (DMFT) that systematically incorporates nonlocal correlations beyond the local correlations treated by DMFT. We apply this approach to investigate how the DMFT critical temperature is suppressed from its mean-field value and how the critical behavior near the finite-temperature phase transition evolves from the mean-field to the Heisenberg universality class. By identifying the symmetry breaking of paramagnetic diagrammatic expansions as a signature of the Néel transition, we accurately predict the Néel temperature of the three-dimensional cubic Hubbard model across all interaction strengths with low computational cost. Introducing a variational order parameter, our method can be applied to both paramagnetic and long-range ordered states, such as antiferromagnetic order. We compute magnetization and antiferromagnetic susceptibility, demonstrating minor corrections to DMFT solutions in the weak-coupling regime while revealing significant modifications to these properties in the intermediate correlation regime. From the analysis of critical exponents, we establish the emergence of Heisenberg critical behavior beyond the mean-field nature of DMFT.

Surface waves, the evanescent solutions of the wave equation at planar discontinuities, are of fundamental importance in surface physics, optics, phononics, electronics, and magnetism. Here, we predict that van der Waals antiferromagnets support surface spin waves that are unique by their extreme (nanoscale) confinement and high group velocity with application potential in ultrafast, nanoscale magnonic devices. These excitations reside within the bulk magnon band gap of type-A van der Waals antiferromagnets (antiferromagnetically coupled ferromagnetic monolayers). In contrast to conventional magnetostatic Damon-Eshbach modes, they are pure exchange modes owing to reduced interlayer exchange coupling at the surface layers, and thus persist in ultrathin multilayer stacks and at large wave numbers. We show that they can be efficiently excited by electromagnetic waves, with absorption power comparable to or even exceeding that of bulk modes. Moreover, their emitted magnetic stray fields exhibit pronounced even-odd oscillations with the number of monolayers that should be observable by nitrogen-vacancy-center magnetometry.

Efficient transport of spin angular momentum is expected to play a crucial role in future spintronic devices, which will potentially operate at frequencies reaching the terahertz range. On the other hand, antiferromagnetic insulators exhibit significant potential for facilitating ultrafast pure spin currents by terahertz magnons. Consequently, we here use femtosecond laser pulses to trigger ultrafast spin currents across thin films of the model antiferromagnet NiO in $\mathrm{Py}|\mathrm{NiO}|\mathrm{Pt}$ stacks, where permalloy (Py) and Pt serve as spin-current source and detector, respectively. We find that the spin-current pulses traversing NiO reach a velocity up to $40\mathrm{nm}/\mathrm{ps}$ and experience increasing attenuation, delay, and broadening as the NiO thickness is increased. We can consistently explain our observations by ballistic transport of incoherent magnons. The relaxation length of 20 nm is 1 order of magnitude larger than for ballistic conduction-electron spin transport in metals and, thus, relevant for potential applications. Methodologically, our all-optical and contact-free spin-conductance approach has large potential to characterize terahertz magnon transport in insulators with any kind of magnetic order.

The material properties of polycrystals are strongly affected by the evolution and coarsening of their internal grain structures. Yet, studying this process is challenging due to the complex interactions within grain boundary networks. Here, we systematically investigate the shrinkage of isolated loop-shaped grain boundaries in 2D colloidal crystals using a combination of simulations and experiments. Unexpectedly, we find that shear coupling decreases with increasing grain misorientation, contrary to geometric predictions. This counterintuitive result is attributed to enhanced concurrent sliding driven by the annihilation of dislocations. Furthermore, by focusing on the evolution of the grain size, we reveal a transition in shrinkage kinetics between small and large loop sizes, providing an explanation for previously observed discrepancies in grain boundary mobility. These findings reveal a more intricate dependence of grain boundary behavior on curvature and misorientation than previously reported, offering new insights into polycrystal coarsening dynamics.

We construct linear and nonlinear entanglement witnesses, by tensoring and partial tracing existing states and witnesses. We show that little shared quantum resources allow one to employ decomposable witnesses to obtain larger ones detecting locally undistillable states and find analytic witnesses for multipartite entangled states that are undistillable across all bipartitions. Crucially, we show how to efficiently optimize multicopy witnesses to desired states, which is a current challenge. As an example of both theoretical and experimental interest, existing trace polynomial witnesses are significantly improved while preserving their symmetries and implementability with randomized measurements. In addition to detecting entanglement, we also find new witnesses detecting $k$-copy distillability. A recipe for the single-copy case is shown to be effective for generic and Werner states.

In most noninteracting quantum systems, the scaling theory of localization predicts one-parameter scaling flow in both ergodic and localized regimes. A corresponding scaling theory of many-body ergodicity breaking is still missing. Here, we introduce a scaling theory of ergodicity breaking in interacting systems, in which the divergent relaxation time follows from the Fermi golden rule, and the observable fluctuations in proximity of the ergodicity breaking critical point are described by the recently introduced fading ergodicity scenario. We argue that, in general, the one-parameter scaling is insufficient, and we show that the scaling theory predicts the critical exponent $\nu =1$ at the ergodicity breaking critical point. Our theoretical framework may serve as a building block for two-parameter scaling theories of many-body systems.

We introduce a framework for describing the real-time dynamics of quantum impurity models out of equilibrium which is based on the influence matrix approach. By replacing the dynamical map of a large fermionic quantum environment with an effective semigroup influence matrix (SGIM) which acts on a reduced auxiliary space, we overcome the limitations of previous proposals, achieving high accuracy at long evolution times. This SGIM corresponds to a uniform matrix-product state representation of the influence matrix and can be obtained by an efficient algorithm presented in this Letter. We benchmark this approach by computing the spectral function of the single impurity Anderson model with high resolution. Further, the spectrum of the effective dynamical map allows us to obtain relaxation rates of the impurity toward equilibrium following a quantum quench. Finally, for a quantum impurity model with on-site two-fermion loss, we compute the spectral function and confirm the emergence of Kondo physics at large loss rates.

We explore a model of free fermions in one dimension, subject to frustrated (noncommuting) local measurements across adjacent sites, which resolves the fermions into nonorthogonal orbitals, misaligned from the underlying lattice. For maximal misalignment, superdiffusive behavior emerges from the vanishing of the measurement-induced quasiparticle decay rate at one point in the Brillouin zone, which generates fractal-scaling entanglement entropy $S\propto {\ell }^{1/3}$ for a subsystem of length $\ell$. We derive an effective nonlinear sigma model with long-range couplings responsible for Lévy flights in entanglement propagation, which we confirm with large-scale numerical simulations. When the misalignment is reduced, the entanglement exhibits, with increasing $\ell$, consecutive regimes of superdiffusive, $S\propto {\ell }^{1/3}$, diffusive, $S\propto \ln \ell$, and localized, $S=\text{const}$, behavior. Our findings show how intricate fractal-scaling entanglement can be produced for local Hamiltonians and measurements.

We explore the fundamental limits on thermodynamic irreversibility when cooling a quantum system in the presence of a finite-size reservoir. First, we prove that, for any noninteracting $n$-particle reservoir, the entropy production $\mathrm{\Sigma }$ decays at most linearly with $n$. Instead, we derive a cooling protocol in which $\mathrm{\Sigma }\propto 1/n^2$, which is, in fact, the best possible scaling. This becomes possible due to the presence of interactions in the finite-size reservoir, which must be prepared at the verge of a phase transition. We further show numerically that an intermediate scaling of $\mathrm{\Sigma }\propto 1/n^{\delta }$ with $\delta \in (1,2)$ can be achieved using a star-network configuration for the reservoir. Our results open the possibility of cooling with a higher energetic efficiency via interacting reservoirs.

Entanglement, while central to quantum technologies, suffers from fragility when exposed to realistic noise. Conventional entanglement distillation tackles this by treating the noisy outputs of an entangling channel as static resources, applying local operations and classical communication after the fact. We challenge this static view. Our approach considers the entangling channel itself as a dynamic, consumable resource, actively purifying it by interposing optimally tailored local unitaries before the channel. We prove that preprocessing achieves entanglement fidelities fundamentally unreachable by any free postprocessing, exposing an intrinsic temporal asymmetry in distillation. Our experimental demonstration not only confirms these findings but also shows that preprocessing can elevate teleportation beyond the classical limit. By integrating theoretical framework with experimental realization, this Letter emphasizes the importance of embracing entanglement’s dynamic nature, paving a more efficient path for optimizing quantum information processing.

Axion dark matter coupled via QCD induces a nonzero differential acceleration between test masses of different composition. Tests of the equivalence principle, like the recent MICROSCOPE space mission, are sensitive to such a signal. We use the final released data of the MICROSCOPE experiment to search for this effect. We find no positive signal consistent with the dark matter model, and set upper limits on the axion-gluon coupling that improve existing laboratory bounds by up to 2 orders of magnitude for axion masses in the ${10}^{-17}$ to ${10}^{-13}\mathrm{eV}$ range.

We uncover late-time gravitational-wave tails in fully nonlinear $3+1$ dimensional numerical relativity simulations of merging black holes, using the highly accurate spec code. We achieve this result by exploiting the strong magnification of late-time tails due to binary eccentricity, recently observed in perturbative evolutions, and showcase here the tail presence in head-on configurations for several mass ratios close to unity. We validate the result through a large battery of numerical tests and detailed comparison with a perturbative evolution, which display striking agreement with full nonlinear ones in the ringdown regime, and very similar tail morphologies. Our results offer yet another confirmation of the highly predictive power of black hole perturbation theory in the presence of a source, even when applied to nonlinear solutions. The late-time tail signal is much more prominent than anticipated until recently, and possibly within reach of gravitational-wave detector measurements, unlocking observational investigations of an additional set of general relativistic predictions on the long-range gravitational dynamics.

We report a study of the semileptonic decays $D^{+}\to K_S^0{\pi }^0{\ell }^{+}{\nu }_{\ell }$ ($\ell =e$, $\mu$) based on $20.3{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The $D^{+}\to K_S^0{\pi }^0{\mu }^{+}{\nu }_{\mu }$ decay is observed for the first time, with a branching fraction of $(0.896\pm 0.017_{\mathrm{stat}}\pm 0.008_{\mathrm{syst}})\%$, and the branching fraction of $D^{+}\to K_S^0{\pi }^0{e}^{+}{\nu }_e$ is determined with the improved precision as $(0.943\pm 0.012_{\mathrm{stat}}\pm 0.010_{\mathrm{syst}})\%$. From the analysis of the dynamics, we observe that the dominant ${\overline{K}}^{*}(892{)}^0$ component is accompanied by an $S$-wave contribution, which accounts for $(7.10\pm 0.68_{\mathrm{stat}}\pm 0.41_{\mathrm{syst}})\%$ of the total decay rate of the ${\mu }^{+}$ channel and $(6.39\pm 0.17_{\mathrm{stat}}\pm 0.14_{\mathrm{syst}})\%$ of the $e^{+}$ channel. Assuming a single-pole dominance parametrization, the hadronic form factor ratios are extracted to be $r_V=V(0)/A_1(0)=1.42\pm 0.03_{\mathrm{stat}}\pm 0.02_{\mathrm{syst}}$ and $r_2=A_2(0)/A_1(0)=0.75\pm 0.03_{\mathrm{stat}}\pm 0.01_{\mathrm{syst}}$. Based on the first comprehensive angular and the decay-rate $CP$ asymmetry analysis, the full set of averaged angular and $CP$ asymmetry observables are measured as a function of the momentum-transfer squared; they are consistent with expectations from the standard model. No evidence for violation of $\mu -e$ lepton-flavor universality is observed in either the full range or the five chosen bins of momentum-transfer squared.

In this Letter we calculate for the first time the next-to-next-to leading order (NNLO) QCD corrections to identified hadron production at hadron colliders. The inclusion of the NNLO correction has an important impact on all observables considered in this Letter. Higher order corrections reduce scale uncertainty and in almost all cases are moderate. Overall, good perturbative convergence is observed across kinematics and observables. The uncertainty due to missing higher orders is relatively small and, in many cases, smaller than the experimental uncertainty. The largest source of theoretical uncertainty at present is from the knowledge of the nonperturbative parton-to-hadron fragmentation functions (FFs), which dwarfs the scale uncertainty in most kinematic ranges. The inclusion of NNLO corrections demonstrates the precision studies potential of this class of observables. To fully realize this potential, however, a new generation of improved fragmentation functions may be needed. The results of the present Letter will enable global fits of FFs with NNLO precision.

Modern collider phenomenology requires unprecedented precision for the theoretical predictions, for which slicing techniques provide an essential tool at next-to-next-to-leading order (NNLO) in the strong coupling. The most popular slicing variable is based on the transverse momentum $q_T$ of a color-singlet final state, but its generalization to final states with jets is known to be very difficult. Here we propose two generalizations of $q_T$ that can be used for jet processes, providing proof of concept with an NLO slicing for $pp\to 2$ jets. We present factorization formulas that enable our approach to NNLO, calculate the NNLO collinear-soft function, and demonstrate slicing at this order for $e^{+}{e}^{-}\to 2$ jets. One of these generalizations of $q_T$ only applies to planar Born processes, such as $pp\to 2$ jets, but offers a dramatic simplification of the soft function. We also discuss how our approach can directly be extended to obtain predictions for the fragmentation of hadrons. This presents a promising path for high-precision QCD calculations with multijet final states.