Volume 17 Issue 7, July 2021

The ATLAS Collaboration has confirmed with top quark events that the coupling of charged leptons to the weak interaction is universal — showcasing the feasibility of performing high-precision electroweak measurements at proton–proton colliders.

Many aspects of gauge theories — such as the one underlying quantum chromodynamics, which describes quark physics — evade common numerical methods. Tensor networks are getting closer to a solution, having successfully tackled the related problem of a three-dimensional quantum link model.

Gradients in the concentration of a solute can drive particle transport by inducing interfacial flows via imbalances in the osmotic pressure near surfaces. Now it seems that this mechanism is directing traffic on the cell membrane.

Introducing non-local effects to metamaterials increases the complexity of their dispersion relation, which allows carefully designed elastic structures to mimic the peculiar roton behaviour of correlated quantum superfluids.

The patterning dynamics of confined immiscible fluids has inspired an elegant and versatile approach to building periodic three-dimensional multi-material architectures. The technique extends to triphasic composites, three-dimensional droplet networks and even biological tissues.

The two-fluid model of superfluids predicts a second, quantum mechanical form of sound. Ultracold atom experiments have now measured second sound in the unusual two-dimensional superfluid described by the Berezinskii–Kosterlitz–Thouless transition.

Cells moving on microprinted tracks reveal a preference for regions that they have already visited, suggesting an update to a century of dynamical models for cell trajectories.

Several cuprate superconductors were recently shown to have chiral phonons. Here second harmonic generation measurements show that antiferromagnetism breaks all mirror symmetries in a related compound, consistent with a chiral state.

The two-dimensional electron gas at an oxide interface is patterned to form a channel with a periodic potential imposed on top. This replicates the textbook Kronig–Penney model and leads to fractionalization of electron bands in the channel.

Transport and thermodynamic measurements on strongly correlated Kondo metal YbB₁₂ reveal the coexistence of charged and charge-neutral fermions in the material and the crucial role played by the latter in the quantum oscillations of resistivity.

The revelation that fluid–fluid interfacial energy can drive structure formation in micropillar scaffolds offers a scalable way of synthesizing soft composites, which may have applications in building materials that mimic biological tissue.

Previously, injections from a conventional accelerator into a plasma-based one suffered from low coupling efficiencies. Now electron bunches are injected with an efficiency of nearly 100% into a laser wakefield accelerator without loss of charge.

The solar wind affects the magnetosphere, but whether this holds true for solar flares was unclear. By combining geospace modelling with observations, solar flares are shown to influence the dynamics of the magnetosphere and its ionosphere coupling.

The ATLAS Collaboration reports a measurement of the ratio of the decay rates of W bosons to τ leptons and muons, in agreement with universal lepton couplings as postulated in the standard model of particle physics.

The ATLAS experiment at the Large Hadron Collider reports a search for charged-lepton-flavour violation in decays of Z bosons into a τ lepton and an electron or muon of opposite charge.

A study of the high-field Hall coefficient in thallium- and bismuth-based single-layer cuprates demonstrates a smooth evolution of this quantity from p to 1 + p over a wide doping range.

A terahertz spectroscopic study of the quasi-one-dimensional ferromagnet CoNb₂O₆ reveals bond-dependent interactions in this material that are similar to those of a one-dimensional version of the honeycomb Kitaev spin liquid.

Quantum systems make it challenging to determine candidate Hamiltonians from experimental data. An automated protocol is presented and its capabilities to infer the correct Hamiltonian are demonstrated in a nitrogen-vacancy centre set-up.

Topologically protected charge transport, known as Thouless pumping, is realized with cold atoms trapped in quasi-periodic disordered potentials. The pumping is disorder-dependent, illustrating the influence of disorder on the topological properties.

Protein oscillations linked to cell division in Escherichia coli are shown to localize unrelated molecules on the cell membrane via a diffusiophoretic mechanism, in which an effective friction fosters cargo transport along the fluxes set up by the proteins.

A computational framework draws analogy with foams to offer a comprehensive picture of how cell behaviours influence fluidization in embryonic tissues, highlighting the role of tension fluctuations in regulating tissue rigidity.

Initially used to measure the brightness of radio sources, the jansky has spread to other areas of astronomy, as Natasha Hurley-Walker recounts.