Speaker
Fazlollah Hajkarim
(University of Oklahoma)
Description
We study how an early matter dominated (EMD) epoch affects the thermal history and first-order phase transitions (FOPT) in the early Universe. A heavy scalar with field-dependent decay width drives reheating, producing non-adiabatic cooling and heating phases. These transitions change the expansion of Universe, shaping the primordial gravitational wave (GW) spectra from FOPT, which can exhibit single or multiple peaks. Our analysis connects scalar properties such as mass and coupling to GW observables, showing how these parameters affect peak frequency and amplitude while remaining consistent with cosmological bounds, thereby offering a probe of beyond Standard Model physics through future GW detections.
Author
Fazlollah Hajkarim
(University of Oklahoma)
