Subatomic, High Energy and Plasma Physics seminar: Nicklas Ramberg

Abstract: Gravitational waves probe hidden sectors through gravity’s universal coupling to energy, with first-order phase transitions in the early Universe or in compact astrophysical objects producing potentially observable signals. In this talk, I will discuss the confinement phase transition in pure SU(Nc) Yang–Mills theory at large Nc, studied within the framework of Improved Holographic QCD.
We construct a microscopic effective action for the confinement order parameter, incorporating both potential and kinetic contributions, and perform an ab initio calculation of confining bubble nucleation at large Nc. This enables a dynamical determination of the surface tension and a direct comparison with lattice QCD results, providing a rare quantitative bridge between holography, nucleation theory, and lattice gauge theory. We further analyze the bubble profile configurations across the entire metastable branch, and conclude by connecting these results to the predicted gravitational-wave signals from this class of theories, commenting on their relevance for ongoing research efforts.