Liquids equilibrated below an onset condition share similar inherent states, while those above that onset have inherent states that markedly differ. Although this type of materials memory was first reported in simulations over 20 years ago, its physical origin remains controversial. Its absence from mean-field descriptions, in particular, has long cast doubt on its thermodynamic relevance. Motivated by a recent theoretical proposal, we reassess the onset phenomenology in simulations using a fast hard sphere jamming algorithm and find it to be both thermodynamically and dimensionally robust. Remarkably, we also uncover a second type of memory associated with a Gardner-like regime of the jamming algorithm.

We show how rigidity emerges in experiments on sheared two-dimensional frictional granular materials by using generalizations of two methods for identifying rigid structures. Both approaches, the force-based dynamical matrix and the topology-based rigidity percolation, agree with each other and identify similar rigid structures. As the system becomes jammed, at a critical contact number $z_c=2.4\pm 0.1$, a rigid backbone interspersed with floppy, particle-filled holes of a broad range of sizes emerges, creating a spongelike morphology. While the pressure within rigid structures always exceeds the pressure outside the rigid structures, they are not identified with the force chains of shear jamming. These findings highlight the need to focus on mechanical stability arising through arch structures and hinges at the mesoscale.

Quantum annealing (QA) and the quantum approximate optimization algorithm (QAOA) are two special cases of the following control problem: apply a combination of two Hamiltonians to minimize the energy of a quantum state. Which is more effective has remained unclear. Here we analytically apply the framework of optimal control theory to show that generically, given a fixed amount of time, the optimal procedure has the pulsed (or “bang-bang”) structure of QAOA at the beginning and end but can have a smooth annealing structure in between. This is in contrast to previous works which have suggested that bang-bang (i.e., QAOA) protocols are ideal. To support this theoretical work, we carry out simulations of various transverse field Ising models, demonstrating that bang-anneal-bang protocols are more common. The general features identified here provide guideposts for the nascent experimental implementations of quantum optimization algorithms.

Weakly interacting Fermi gases simulate spin lattices in energy space, offering a rich platform for investigating information spreading and spin coherence in a large many-body quantum system. We show that the collective spin vector can be determined as a function of energy from the measured spin density, enabling general energy-space resolved protocols. We measure an out-of-time-order correlation function in this system and observe the energy dependence of the many-body coherence.

We calculate the axion emission rate from reactions involving thermal pions in matter encountered in supernovae and neutron star mergers, identify unique spectral features, and explore their implications for astrophysics and particle physics. We find that it is about 2–5 times larger than nucleon-nucleon bremsstrahlung, which in past studies was considered to be the dominant process. The axion spectrum is also found be much harder. Together, the larger rates and higher axion energies imply a stronger bound on the mass of the QCD axion and better prospects for direct detection in a large underground neutrino detector from a nearby galactic supernova.

ANITA’s fourth long-duration balloon flight in 2016 detected 29 cosmic-ray (CR)-like events on a background of ${0.37}_{-0.17}^{+0.27}$ anthropogenic events. CRs are mainly seen in reflection off the Antarctic ice sheets, creating a phase-inverted waveform polarity. However, four of the below-horizon CR-like events show anomalous noninverted polarity, a $p=5.3\times {10}^{-4}$ chance if due to background. All anomalous events are from locations near the horizon; ANITA-IV observed no steeply upcoming anomalous events similar to the two such events seen in prior flights.

We present a new bound on the ultralight axion (ULA) dark matter mass $m_{\mathrm{a}}$, using the Lyman-alpha forest to look for suppressed cosmic structure growth: a 95% lower limit $m_{\mathrm{a}}>2\times {10}^{-20}\mathrm{eV}$. This strongly disfavors ($>99.7\%$ credibility) the canonical ULA with ${10}^{-22}\mathrm{eV}<m_{\mathrm{a}}<{10}^{-21}\mathrm{eV}$, motivated by the string axiverse and solutions to possible tensions in the cold dark matter model. We strengthen previous equivalent bounds by about an order of magnitude. We demonstrate the robustness of our results using an optimized emulator of improved hydrodynamical simulations.

We propose a novel mechanism to test time variation of the propagation speed of gravitational waves (GWs) in light of GWs astronomy. As the stochastic GWs experience the whole history of cosmic expansion, they encode potential observational evidence of such variation. We report that, one feature of a varying GWs speed is that the energy spectrum of GWs will present resonantly enhanced peaks if the GWs speed oscillates in time at high-energy scales. Such oscillatory behavior arises in a wide class of modified gravity theories. The amplitude of these peaks can be at reach by current and forthcoming GWs instruments, hence making the underlying theories falsifiable. This mechanism reveals that probing the variation of GWs speed can be a promising way to search for new physics beyond general relativity.

We provide gauge/gravity dual descriptions of explicit realizations of the strong coupling sector of composite Higgs models using insights from nonconformal examples of the AdS/CFT correspondence. We calculate particle masses and pion decay constants for proposed Sp(4) and SU(4) gauge theories, where there is the best lattice data for comparison. Our results compare favorably to lattice studies and go beyond those due to a greater flexibility in choosing the fermion content. That content changes the running dynamics and its choice can lead to sizable changes in the bound state masses. We describe top partners by a dual fermionic field in the bulk. Including suitable higher dimension operators can ensure a top mass consistent with the standard model.

The MoEDAL trapping detector consists of approximately 800 kg of aluminum volumes. It was exposed during run 2 of the LHC program to $6.46{\mathrm{fb}}^{-1}$ of 13 TeV proton-proton collisions at the LHCb interaction point. Evidence for dyons (particles with electric and magnetic charge) captured in the trapping detector was sought by passing the aluminum volumes comprising the detector through a superconducting quantum interference device (SQUID) magnetometer. The presence of a trapped dyon would be signaled by a persistent current induced in the SQUID magnetometer. On the basis of a Drell-Yan production model, we exclude dyons with a magnetic charge ranging up to five Dirac charges ($5g_D$) and an electric charge up to 200 times the fundamental electric charge for mass limits in the range 870–3120 GeV and also monopoles with magnetic charge up to and including 5$g_D$ with mass limits in the range 870–2040 GeV.

We present for the first time complete next-to-next-to-leading-order coefficient functions to match flavor nonsinglet quark correlation functions in position space, which are calculable in lattice QCD, to parton distribution functions (PDFs). Using PDFs extracted from experimental data and our calculated matching coefficients, we predict valence-quark correlation functions that can be confronted by lattice QCD calculations. The uncertainty of our predictions is greatly reduced with higher order matching coefficients. By performing Fourier transformation, we also obtain matching coefficients for corresponding quasi-PDFs and pseudo-PDFs. Our method of calculations can be readily generalized to evaluate the matching coefficients for sea-quark and gluon correlation functions, making the program to extract partonic structure of hadrons from lattice QCD calculations comparable with and complementary to that from experimental measurements.

We present the next-to-next-to-leading order (NNLO) calculation of quark quasiparton distribution functions (PDFs) in the large momentum effective theory. The nontrivial factorization at this order is established explicitly and the full analytic matching coefficients between the quasidistribution and the light-cone distribution are derived. We demonstrate that the NNLO numerical contributions can improve the behavior of the extracted PDFs sizably. With the unprecedented precision study of nucleon tomography at the planned electron-ion collider, high precision lattice QCD simulations with our NNLO results implemented will enable to test the QCD theory and more precise results on the PDFs of nucleons will be obtained.

The yield of charged particles opposite to a $Z$ boson with large transverse momentum ($p_T$) is measured in $260{\mathrm{pb}}^{-1}$ of $pp$ and $1.7{\mathrm{nb}}^{-1}$ of $\mathrm{Pb}+\mathrm{Pb}$ collision data at 5.02 TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider. The $Z$ boson tag is used to select hard-scattered partons with specific kinematics, and to observe how their showers are modified as they propagate through the quark-gluon plasma created in $\mathrm{Pb}+\mathrm{Pb}$ collisions. Compared with $pp$ collisions, charged-particle yields in $\mathrm{Pb}+\mathrm{Pb}$ collisions show significant modifications as a function of charged-particle $p_T$ in a way that depends on event centrality and $Z$ boson $p_T$. The data are compared with a variety of theoretical calculations and provide new information about the medium-induced energy loss of partons in a $p_T$ regime difficult to measure through other channels.

Single-photon pulses cannot be generated on demand, due to incompatible requirements of positive frequencies and positive times. Resulting states therefore contain small probabilities for multiphotons. We derive upper and lower bounds for the maximum fidelity of realizable states that approximate single-photon pulses. The bounds have implications for ultrafast optics; the maximum fidelity is low for pulses with few cycles or close to the onset, but increases rapidly as the pulse envelope varies more slowly. We also demonstrate strictly localized states that are close to single photons.

We present a metastructure architecture with a bistable microstructure that enables extreme broadband frequency conversion. We use numerical and experimental tools to unveil the relationship between input excitations at the unit cell level and output responses at the macrostructural level. We identify soliton-lattice mode resonances resulting in input-independent energy transfer into desired metabeam vibration modes as long as transition waves are triggered within the metastructure. We observe both low-to-high and high-to-low incommensurate frequency interactions in the metabeams, thus enabling energy exchange between bands 2 orders of magnitude apart. This behavior generalizes fluxon-cavity mode resonance in superconducting electronics, providing a general method to extreme frequency conversion in mechanics. Importantly, the introduced architecture allows for expanding the metamaterials design paradigm by fundamentally breaking the dependence of macroscopic dynamics on the unit cell properties. The resulting input-independent nature implies potential applications in broadband frequency regulation and energy transduction.

We solve the advection-diffusion equation for a stochastically stationary passive scalar $\theta$, in conjunction with forced 3D Navier-Stokes equations, using direct numerical simulations in periodic domains of various sizes, the largest being ${8192}^3$. The Taylor-scale Reynolds number varies in the range 140–650 and the Schmidt number $\mathrm{Sc}\equiv \nu /D$ in the range 1–512, where $\nu$ is the kinematic viscosity of the fluid and $D$ is the molecular diffusivity of $\theta$. Our results show that turbulence becomes an ineffective mixer when Sc is large. First, the mean scalar dissipation rate $⟨\chi ⟩=2D⟨|\nabla \theta {|}^2⟩$, when suitably nondimensionalized, decreases as $1/\log \mathrm{Sc}$. Second, 1D cuts through the scalar field indicate increasing density of sharp fronts on larger scales, oscillating with large excursions leading to reduced mixing, and additionally suggesting weakening of scalar variance flux across the scales. The scaling exponents of the scalar structure functions in the inertial-convective range appear to saturate with respect to the moment order and the saturation exponent approaches unity as Sc increases, qualitatively consistent with 1D cuts of the scalar.

We measure cross-beam energy transfer (CBET) saturation by ion heating in a gas-jet plasma characterized using Thomson scattering. A wavelength-tunable ultraviolet (UV) probe laser beam interacts with four intense UV pump beams to drive large-amplitude ion-acoustic waves. For the highest-intensity interactions, the power transfer to the probe laser drops, demonstrating ion-acoustic wave saturation. Over this time, the ion temperature is measured to increase by a factor of 7 during the 500-ps interaction. Particle-in-cell simulations show ion trapping and a subsequent ion heating consistent with measurements. Linear kinetic CBET models are found to agree well with the observed energy transfer when the measured plasma conditions are used.

Supercell models are often used to calculate the electronic structure of local deviations from the ideal periodicity in the bulk or on the surface of a crystal or in wires. When the defect or adsorbent is charged, a jellium counter charge is applied to maintain overall neutrality, but the interaction of the artificially repeated charges has to be corrected, both in the total energy and in the one-electron eigenvalues and eigenstates. This becomes paramount in slab or wire calculations, where the jellium counter charge may induce spurious states in the vacuum. We present here a self-consistent potential correction scheme and provide successful tests of it for bulk and slab calculations.

A recently developed formula for the Hall coefficient [A. Auerbach, Phys. Rev. Lett. 121, 066601 (2018)] is applied to nodal line and Weyl semimetals (including graphene) and to spin-orbit split semiconductor bands in two and three dimensions. The calculation reduces to a ratio of two equilibrium susceptibilities, where corrections are negligible at weak disorder. Deviations from Drude’s inverse carrier density are associated with band degeneracies, Fermi surface topology, and interband currents. Experiments which can measure these deviations are proposed.