Title: Gauge-Invariant Analysis of Curvature Perturbations and Gravitational Waves from Slow First-Order Phase Transitions

Speaker: Professor Ran Ding (Anhui University)

Time: 11:00am, June 4, 2026

Location: 3-201, PMO Xianlin Campus

Abstract: When strongly supercooled cosmological first-order phase transitions (FOPTs) proceed sufficiently slowly, superhorizon inhomogeneities can be generated. We compute these super-horizon curvature perturbations using a gauge-invariant multi-fluid formalism. We show that primordial black holes are unlikely to form from such inhomogeneities, and derive a fitting formula for the resulting curvature perturbations as well as the associated scalar-induced gravitational waves. In the second part of this talk, I will briefly present our recent work on the radio detection of the high-frequency gravitational wave background based on the Hongmeng Project.