The first measurement at the LHC of charge-dependent directed flow ($v_1$) relative to the spectator plane is presented for Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. Results are reported for charged hadrons and ${\mathrm{D}}^0$ mesons for the transverse momentum intervals $p_{\mathrm{T}}>0.2\mathrm{GeV}/c$ and $3<p_{\mathrm{T}}<6\mathrm{GeV}/c$ in the 5%–40% and 10%–40% centrality classes, respectively. The difference between the positively and negatively charged hadron $v_1$ has a positive slope as a function of pseudorapidity $\eta$, $\mathrm{d}\mathrm{\Delta }{v}_1/\mathrm{d}\eta =[1.68\pm 0.49(\mathrm{stat})\pm 0.41(\mathrm{syst})]\times {10}^{-4}$. The same measurement for ${\mathrm{D}}^0$ and ${\overline{\mathrm{D}}}^0$ mesons yields a positive value $\mathrm{d}\mathrm{\Delta }{v}_1/\mathrm{d}\eta =[4.9\pm 1.7(\mathrm{stat})\pm 0.6(\mathrm{syst})]\times {10}^{-1}$, which is about 3 orders of magnitude larger than the one of the charged hadrons. These measurements can provide new insights into the effects of the strong electromagnetic field and the initial tilt of matter created in noncentral heavy ion collisions on the dynamics of light (u, d, and s) and heavy (c) quarks. The large difference between the observed $\mathrm{\Delta }{v}_1$ of charged hadrons and ${\mathrm{D}}^0$ mesons may reflect different sensitivity of the charm and light quarks to the early time dynamics of a heavy ion collision. These observations challenge some recent theoretical calculations, which predicted a negative and an order of magnitude smaller value of $\mathrm{d}\mathrm{\Delta }{v}_1/\mathrm{d}\eta$ for both light flavor and charmed hadrons.

We demonstrate a versatile, state-dependent trapping scheme for the ground and first excited rotational states of ${}^{23}\mathrm{Na}{}^{40}\mathrm{K}$ molecules. Close to the rotational manifold of a narrow electronic transition, we determine tune-out frequencies where the polarizability of one state vanishes while the other remains finite, and a magic frequency where both states experience equal polarizability. The proximity of these frequencies of only 10 GHz allows for dynamic switching between different trap configurations in a single experiment, while still maintaining sufficiently low scattering rates.

In many physics fields, the radio emission of a composite system composed of a large number of randomly occurring but similar emission sources is encountered. In general, the composite system lasts longer than each individual component and individual source currents vary much more rapidly. This Letter presents a theory to understand the electromagnetic radiation spectrum of such a system. If the temporal distribution of the random occurrence of the component and the distribution to describe the relevant emission source properties are known, the spectrum of the composite system can be readily found from this theory. There are two main terms that define the spectrum: one term results from the coherent summation of the contributions from individual sources and is proportional to the square of the total number of the components in the system; the other term results from an incoherent summation and is proportional to the first power of that number. This can lead to drastically different spectral magnitudes in different spectral regions, typically with the spectral magnitude in the lower frequency region many orders of magnitude stronger than that in the higher frequency region.

We perform a statistical study of the turbulent power spectrum at inertial and kinetic scales observed during the first perihelion encounter of the Parker Solar Probe. We find that often there is an extremely steep scaling range of the power spectrum just above the ion-kinetic scales, similar to prior observations at 1 A.U., with a power-law index of around $-4$. Based on our measurements, we demonstrate that either a significant ($>50\%$) fraction of the total turbulent energy flux is dissipated in this range of scales, or the characteristic nonlinear interaction time of the turbulence decreases dramatically from the expectation based solely on the dispersive nature of nonlinearly interacting kinetic Alfvén waves.

Quantum gas microscopy has emerged as a powerful new way to probe quantum many-body systems at the microscopic level. However, layered or efficient spin-resolved readout methods have remained scarce as they impose strong demands on the specific atomic species and constrain the simulated lattice geometry and size. Here we present a novel high-fidelity bilayer readout, which can be used for full spin- and density-resolved quantum gas microscopy of two-dimensional systems with arbitrary geometry. Our technique makes use of an initial Stern-Gerlach splitting into adjacent layers of a highly stable vertical superlattice and subsequent charge pumping to separate the layers by $21\mu \mathrm{m}$. This separation enables independent high-resolution images of each layer. We benchmark our method by spin- and density-resolving two-dimensional Fermi-Hubbard systems. Our technique furthermore enables the access to advanced entropy engineering schemes, spectroscopic methods, or the realization of tunable bilayer systems.

The Peierls instability toward a charge density wave is a canonical example of phonon-driven strongly correlated physics and is intimately related to topological quantum matter and exotic superconductivity. We propose a method for realizing an analogous photon-mediated Peierls transition, using a system of one-dimensional tubes of interacting Bose or Fermi atoms trapped inside a multimode confocal cavity. Pumping the cavity transversely engineers a cavity-mediated metal-to-insulator transition in the atomic system. For strongly interacting bosons in the Tonks-Girardeau limit, this transition can be understood (through fermionization) as being the Peierls instability. We extend the calculation to finite values of the interaction strength and derive analytic expressions for both the cavity field and mass gap. They display nontrivial power law dependence on the dimensionless matter-light coupling.

Exploiting simple yet remarkable properties of relativistic gravitational scattering, we use first-order self-force (linear-in-mass-ratio) results to obtain arbitrary-mass-ratio results for the complete third-subleading post-Newtonian (4.5PN) corrections to the spin-orbit sector of spinning-binary conservative dynamics, for generic (bound or unbound) orbits and spin orientations. We thereby improve important ingredients of models of gravitational waves from spinning binaries, and we demonstrate the improvement in accuracy by comparing against aligned-spin numerical simulations of binary black holes.

We report observations of coherent optical transition radiation interferometry (COTRI) patterns generated by microbunched $\sim 200\text{−}\mathrm{MeV}$ electrons as they emerge from a laser-driven plasma accelerator. The divergence of the microbunched portion of electrons, deduced by comparison to a COTRI model, is $\sim 9\times$ smaller than the $\sim 3\mathrm{mrad}$ ensemble beam divergence, while the radius of the microbunched beam, obtained from COTR images on the same shot, is $<3\mu \mathrm{m}$. The combined results show that the microbunched distribution has estimated transverse normalized emittance $\sim 0.4\mathrm{mm}\mathrm{mrad}$.

Diffractive photonic devices manipulate light via local and nonlocal optical modes. Local devices, such as metasurfaces, can shape a wave front at multiple selected wavelengths, but inevitably modify light across the spectrum; nonlocal devices, such as grating filters, offer great frequency selectivity but limited spatial control. Here, we introduce a rational design paradigm using quasibound states in the continuum to realize multifunctional nonlocal devices: metasurfaces that produce narrow band spatially tailored wave fronts at multiple selected wavelengths and yet are otherwise transparent.

Many types of cells require the ability to pinpoint the location of an external stimulus from the arrival of diffusing signaling molecules at cell-surface receptors. How does the organization (number and spatial configuration) of these receptors shape the limit of a cell’s ability to infer the source location? In the idealized scenario of a spherical cell, we apply asymptotic analysis to compute splitting probabilities between individual receptors and formulate an information-theoretic framework to quantify the role of receptor organization. Clustered configurations of receptors provide an advantage in detecting sources aligned with the clusters, suggesting a possible multiscale mechanism for single-cell source inference.

Thermal noise associated with the mechanical loss of current highly reflective mirror coatings is a critical limit to the sensitivity of gravitational-wave detectors. Several alternative coating materials show potential for reducing thermal noise, but cannot be used due to their high optical absorption. Multimaterial coatings have been proposed to enable the use of such materials to reduce thermal noise while minimizing their impact on the total absorption of the mirror coating. Here we present experimental verification of the multimaterial concept, by integrating aSi into a highly reflective ${\mathrm{SiO}}_2$ and ${\mathrm{Ta}}_2{\mathrm{O}}_5$ multilayer coating. We show a significant thermal noise improvement and demonstrate consistent optical and mechanical performance. The multimaterial coating survives the heat treatment required to minimize the absorption of the aSi layers, with no adverse effects from the different thermomechanical properties of the three materials.

The late stages of the relaxation process of a black hole are expected to depend only on its mass and angular momentum and not on the details of its formation process. Inspired by recent analogue gravity experiments, which demonstrate that certain black hole processes take place in gravitational and hydrodynamical systems alike, we conduct an experiment to search for quasinormal mode oscillations of the free surface of a hydrodynamical vortex flow. Our results demonstrate the occurrence and hint at the ubiquity of quasinormal ringing in nonequilibrium analog black hole experiments.

We show that an axionlike field coupled to a new confining gauge group can generate the primordial density perturbation in the postinflation Universe. The axion decay constant and strong coupling scale are uniquely determined by observations of the density perturbation, which further suggest a temporal deconfinement of the gauge group after inflation. The resulting temperature-dependent axion potential, together with its periodic nature, gives rise to the red-tilted density perturbation, with a positive local-type non-Gaussianity of order unity.

We present the first search for bosonic superweakly interacting massive particles (super-WIMPs) as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-$\beta$ decay experiment which operates high-purity germanium detectors enriched in ${}^{76}\mathrm{Ge}$ in an ultralow background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from $60\mathrm{keV}/c^2$ to $1\mathrm{MeV}/c^2$. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above $120\mathrm{keV}/c^2$ have been set. As an example, at a mass of $150\mathrm{keV}/c^2$ the most stringent direct limits on the dimensionless couplings of axionlike particles and dark photons to electrons of $g_{ae}<3\times {10}^{-12}$ and ${\alpha }^{\prime }/\alpha <6.5\times {10}^{-24}$ at 90% credible interval, respectively, were obtained.

The modification of the ground state properties of light atomic nuclei in the nuclear and stellar medium is addressed, using chemical equilibrium constants evaluated from a new analysis of the intermediate energy heavy-ion ($\mathrm{Xe}+\mathrm{Sn}$) collision data measured by the INDRA Collaboration. Three different reactions are considered, mainly differing by the isotopic content of the emission source. The thermodynamic conditions of the data samples are extracted from the measured multiplicities allowing for a parametrization of the in-medium modification, determined with the single hypothesis that the different nuclear species in a given sample correspond to a unique common value for the density of the expanding source. We show that this correction, which was not considered in previous analyses of chemical constants from heavy-ion collisions, is necessary, since the observables of the analyzed systems show strong deviations from the expected results for an ideal gas of free clusters. This dataset is further compared to a relativistic mean-field model, and seen to be reasonably compatible with a universal correction of the attractive $\sigma$-meson coupling.

Alignment of OCS, ${\mathrm{CS}}_2$, and ${\mathrm{I}}_2$ molecules embedded in helium nanodroplets is measured as a function of time following rotational excitation by a nonresonant, comparatively weak ps laser pulse. The distinct peaks in the power spectra, obtained by Fourier analysis, are used to determine the rotational, $B$, and centrifugal distortion, $D$, constants. For OCS, $B$ and $D$ match the values known from IR spectroscopy. For ${\mathrm{CS}}_2$ and ${\mathrm{I}}_2$, they are the first experimental results reported. The alignment dynamics calculated from the gas-phase rotational Schrödinger equation, using the experimental in-droplet $B$ and $D$ values, agree in detail with the measurement for all three molecules. The rotational spectroscopy technique for molecules in helium droplets introduced here should apply to a range of molecules and complexes.

We present the detection of the highly forbidden $2{{}^{3}S}_1\to 3{{}^{3}S}_1$ atomic transition in helium, the weakest transition observed in any neutral atom. Our measurements of the transition frequency, upper state lifetime, and transition strength agree well with published theoretical values and can lead to tests of both QED contributions and different QED frameworks. To measure such a weak transition, we develop two methods using ultracold metastable ($2{{}^{3}S}_1$) helium atoms: low background direct detection of excited then decayed atoms for sensitive measurement of the transition frequency and lifetime, and a pulsed atom laser heating measurement for determining the transition strength. These methods could possibly be applied to other atoms, providing new tools in the search for ultraweak transitions and precision metrology.