Author(s): Xing-Yu Yang (杨星宇), Tan Chen (陈坦), and Rong-Gen Cai (蔡荣根) We show that oscillating (real-scalar) boson stars generically host an oscillating radial caustic. Sources near this caustic cross it every half period, thereby producing periodic caustic-crossing lensing. The resulting observables are phase locked to the lens oscillation: image-pair creation or ann… [Phys. Rev. Lett. 137, 031403] Published Fri Jul 17, 2026