Programme

O.1 -- Oral, VCTP-51

Date: Monday, 3 August 2026

Time: 11:10 - 11:30

Probing axion in the DFSZ model

Hoang Ngoc Long, Nguyen Hua Thanh Nha

Science and Technology Advanced Institute, Van Lang University, Ho Chi Minh City, Vietnam

We show that within new right-handed neutrinos $N_R$, the Peccei - Quinn (PQ) transformation in the DFSZ (Dine-Fischler-Srednicki-Zhitnitsky) depends only on PQ charge of scalar singlet $\phi$, it depends on just PQ charge of the scalar singlet $PQ_\phi$ but not in the latter and sine/cosine of $ \arctan (v_u/v_d)$. The model consists of four new scalars: charged $H^\pm$, CP-odd $A$ and CP-even with masses at the EW scale (few hundreds GeVs) and a super heavy inflaton $\Phi$. The invariance of the model under the PQ transformation leads to the form of axion state, in which VEVs lie in the nominators. The scalar fields have been presented in a form of unitary matrices in which there is no mixing among axion and Goldstone boson $G_Z$. As a result, there are two kinds of couplings between axion and fermions, namely Yukawa-like interactions and anomaly ones associated with derivative of the axion. The branching decay of Higgs boson into an axion pair is derived.

Presenter: Hoang Ngoc Long