Summer Institute 2025 (Aug 17 - 22, 2025)

Session

Parallel session 6

21 Aug 2025, 14:00

Utop Marina Hotel & Resort, Yeosu, Korea

Conveners

Parallel session 6

• Jeong Han Kim (Chungbuk National University)

6. Gravitational wave signatures of dark sector portal leptogenesis

Indrajit Saha (Indian Institute of Technology Guwahati, Assam, India)

21/08/2025, 14:00

Parallel talk

We study the possibility of probing leptogenesis via stochastic gravitational waves (GW) arising from a dark sector assisted first-order electroweak phase transition. The same dark sector, with non-trivial transformation under an unbroken $Z_2$ symmetry is also responsible for providing the only source of CP asymmetry via one-loop interference with the tree level decay of a heavy right-handed...

7. Leptogenesis from a Phase Transition in a Dynamical Vacuum

Dipendu Bhandari (IIT Guwahati)

21/08/2025, 14:20

Parallel talk

We show that a phase transition may take place in the early Universe at a temperature $T_*$ resulting a temperature dependent mass for right handed neutrinos (RHN) which finally relaxes to a constant value after electroweak symmetry breaking (EWSB). As a result, a requisite amount of lepton asymmetry can be produced near $T_*$ satisfying the observed baryon asymmetry of the Universe via...

9. Thermal leptogenesis in SO(10)× U(1)_A GUT

Kei SHIBATA (Nagoya Univ.)

21/08/2025, 14:40

Parallel talk

In this study, we show that thermal leptogenesis can be realized within the framework of the $SO(10)\times U(1)_A$ grand unified theory(GUT). Furthermore, by including flavor effects, we have found that the second-lightest right-handed neutrino makes a significant contribution. As a result, the mass derived in this study is approximately six times larger than the mass predicted for the...

14. Decoherence of primordial perturbations in the view of a local observer

Fumiya Sano (Tokyo Institute of Technology / Institute for Basic Science)

21/08/2025, 15:00

Parallel talk

We study quantum decoherence of curvature perturbations at superhorizon scales caused by the gravitational nonlinearities. We show that cubic gravitational couplings, constrained by the spatial diffeomorphism invariance, lead to infrared (IR) and ultraviolet (UV) divergences in the decoherence rate at one loop. These divergences arise from fluctuations of deep IR modes which look like a...

16. Detectability of the phase transition gravitational waves in the DFSZ axion model

Ms AiDi Yang (Sun Yat-sen University)

21/08/2025, 15:20

Parallel talk

In recent years, an increasing number of studies have focused on using gravitational waves to explore axions and the dynamics of Peccei-Quinn symmetry breaking at high energy scales in the early universe. To accurately quantify the capability of specific gravitational wave experiments to probe the axion properties, it is crucial to perform precise calculations of gravitational wave signals...

17. Refining Gravitational Wave and Collider Physics Dialogue via Singlet Scalar Extension

Van Que Tran (NCTS, National Taiwan University)

21/08/2025, 15:40

Parallel talk

Employing effective field theory techniques, we advance computations of thermal parameters that enter predictions for the gravitational wave spectra from first-order electroweak phase transitions. Working with the real-singlet-extended Standard Model, we utilize recent lattice simulations to confirm the existence of first-order phase transitions across the free parameter space. For the first...