Particle Theory Seminars

The particle theory seminars are organized by the Theory Group of the Laboratory for Particle Physics (LTP) at PSI.

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The last seminar took place on Friday, February 21 at 11:30 AM in WHGA/121

Speaker: Lisa Biermann (PSI)

Title: Aspects of the Electroweak Phase Transition

Abstract

The hot early universe might have been in a different ground state than our universe today. This opens the possiblity that our universe transitioned from a high-temperature vacuum (which for example restores the electroweak symmetry) to the low-temperature vacuum of today in which the electroweak symmetry is spontaneously broken via an electroweak phase transition (EWPT). Models beyond the Standard Model (BSM) can (unlike the Standard Model) encorporate a (strong) first-order EWPT while also reproducing all experimental collider data. This additional possibility of a strong first-order EWPT can then serve as the required departure from thermal equilibrium, allowing to explain the observed matter-antimatter asymmetry of the universe at the electroweak scale. Furthermore, a first-order EWPT sources a stochastic gravitational wave background to which e.g. the future space-bound gravitational wave observatory LISA might become sensitive.

In this talk, I will dive into finite-temperature field theory and present several BSM extensions of the scalar sector that allow for first-order electroweak phase transitions, as well as observable gravitational waves. I will highlight how EWPTs position these models at the intersection of collider phenomenology and cosmology, i.e. how they are tested from these two perspectives.