DPF - PHENO 2024

Connecting low-scale and high-scale CP violation in Left-Right Symmetric Model with double seesaw

Not scheduled

15m

Lawrence Hall

Neutrino Physics Neutrino Physics

Speaker

Dr Purushottam Sahu (Indian Institute Of Technology Bombay, India)

Description

We study the link between low-scale CP-violating Dirac phase $(\delta )$ and high-scale leptogenesis in a Left-Right Symmetric Model (LRSM) with scalar bidoublet and doublets. The model's fermion sector includes one sterile neutrino $(S_L)$ for each generation, resulting in a double seesaw mechanism in the neutral fermion mass matrix. The double seesaw is achieved by implementing the type-I seesaw twice. The first seesaw generates the Majorana mass term for heavy right-handed (RH) neutrinos $(N_R)$, whereas the light neutrino mass becomes linearly dependent on $S_L$ mass in the subsequent one. In our approach, we use charge conjugation ($C$) as the discrete left-right (LR) symmetry. This decision helps to calculate the Dirac neutrino mass matrix ($M_D$) by taking into account the light and heavy RH neutrino masses, as well as the light neutrino mixing matrix $U_{PMNS}$ (which includes $\delta$). We demonstrate the possibility of unflavored thermal leptogenesis via RH neutrinos decay by employing the obtained $M_D$ and RH neutrinos masses as input parameters. In the unflavored regime, a thorough analysis of the Boltzmann equations describing the asymmetry evolution is performed, and it is demonstrated that, with or without Majorana phases, the CP-violating Dirac phase is sufficient to produce the required asymmetry in the leptonic sector within this framework for a given set of input parameters. Finally, we discuss the feasibility of constraining our model with current and near-future oscillation experiments to refine the value of $\delta$.