Neutrinos and atoms shed light on neutral currents

Over the past three years, evidence for the existence of neutral currents has grown ever stronger. Such currents are generally required by various gauge theories that have been developed in an attempt to unify the weak and electromagnetic interactions. Many observations of neutrino interactions are consistent with the model proposed a decade ago by Steven Weinberg and by Abdus Salam. However, two experiments cast a small shadow of doubt on the minimal model: the so‐called “high‐y anomaly” in antineutrino inelastic scattering and preliminary results on parity violation (or lack of it) in atomic physics.