Speaker
Yun Jiang
Description
We study cosmological phase transitions in the low-nucleation-rate regime, where standard bubble percolation fails. Two distinct mechanisms emerge: (i) a bubble-free transition, in which a higher-energy vacuum within domain walls classically decays into the true vacuum, and (ii) super-Hubble separated bubbles, leading to ultra-supercooled or reheated transitions. These scenarios reveal unconventional dynamical pathways with significant implications for early-Universe evolution and gravitational-wave phenomenology.