Speaker
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 $\delta$.
