Programme

P.100 -- Posters, VCTP-50

Date: Thursday, 7 August 2025

Time: 08:30 - 10:00

Dark matter relic abundance in an extended scalar sector with vector-like quarks

Nguyen Minh Hien (1), Dao Thi Nhung (2)

(1) University of Science, VNU-HCM; (2) Phenikaa University

This thesis investigates a minimal extension of the Standard Model (SM) that incorporates a $Z_2$-odd inert scalar doublet, a real singlet scalar, and vector-like quarks (VLQs). The model provides a viable candidate for scalar dark matter and allows for additional heavy scalar states that mix via a real orthogonal rotation. Only the SM Higgs doublet acquires a vacuum expectation value, preserving the $Z_2$ symmetry and ensuring dark matter stability. Particular attention is paid to the scalar sector, where mixing effects and CP assignments are carefully implemented. We classify all relevant interaction vertices and analyze dark sector phenomenology through scalar pair annihilation and co-annihilation processes into SM particles. We compute the squared matrix elements, perform interference analysis, and study resonance structures in the total annihilation cross section, using the standard freeze-out method to determine the relic abundance. Our results focus on identifying model configurations that yield a relic density compatible with observational data, thereby providing a robust foundation for further exploration of dark matter dynamics in extended scalar sectors.

Presenter: Nguyen Minh Hien