Study of Neutrinoless Double Beta Decay & Lepton Flavour Violation in Standard Model Extended with Sterile Neutrinos

Abstract

Existence of non-interacting fermion singlets, known as sterile neutrinos, are contextualised in be­yond standard model physics. From accommodating oscillation anomalies to play a role of messen­ger for neutrino mass generation mechanism through type-I seesaw, they have blossomed as a key ingredient with their several mass variants. In addition, being a standard model singlet, they are accessible to acquire majorana type mass and hence triggers lepton number violation (LNV} and charged lepton flavour violation (cLFV) processes. Driven by this fact, we are intended to work with incorporation of 3 sterile states N;, i = 1, 2, 3 with mass IV!;, i = 1, 2, 3 along with the standard model active neutrinos, thus presenting a 3+3 model for calculation of the effective mass lmee I of neutrino less double beta (Ov{:3(:3) decay which comes as prior of interest in the context ofLNV pro­ cess. We have derived the analytical forms for the added sterile states using exact seesaw relation. In this context, the additional cp violating (CPV) phases and active-sterile mixing angle values are also explored. Following the experimental limit of lmeel, we have obtained the involved sterile states in the KeV-MeV range. Interestingly, most of the KeV range sterile stated are found to follow the hierarchical pattern i.e., for NH (M1 > lvI2 > !11[3) and for IH (/v/1 < !11[2 < /tl[3). We have also checked the reliability of our result by calculating the branching ratio ofµ 􀀁 eAf, a prominent cLFV process, in the 3+3 framework. Significant results on BR(µ 􀀁 e"f) are found for KeV range sterile neutrinos with their corresponding CPV phase and active-sterile mixing angle values.