The muon anomalous magnetic moment (g–2) reports tantalising tensions with the Standard Model. But what about tau g–2? Remarkably, tau g–2 remains poorly constrained but can be 280 times more sensitive to new physics than the muon. Recently, CMS and ATLAS announced groundbreaking measurements of tau g–2 competitive with LEP using the landmark observation of tau pairs created via photon collisions in LHC heavy-ion data. Beyond colliders, limitations with existing searches for axions motivate the Broadband Reflector Experiment for Axion Detection (BREAD) proposal at Fermilab. Recent quantum sensing progress enables BREAD to open multi-decade discovery sensitivity to axion dark matter above microwave frequencies that has long eluded cavity haloscopes. BREAD provides an exciting nexus for interdisciplinary science bridging astronomy, particle physics, and quantum technology.
Costas Andreopoulos; Jan Kretzschmar