# Investigating two heavy neutral leptons neutrino seesaw mechanism at SHiP

## TL;DR

This paper explores the potential of the SHiP experiment to investigate a minimal type-I seesaw model with two heavy neutral leptons, focusing on active-sterile mixing and implications for neutrino mass generation.

## Contribution

It analyzes the sensitivity of SHiP to a minimal seesaw model with two heavy neutral leptons, highlighting the role of active-sterile mixing and phase correlations.

## Key findings

- High active-sterile mixing angles require phase correlations.
- Current neutrinoless double beta decay limits are not restrictive for SHiP.
- SHiP can probe parameter space relevant to neutrino mass models.

## Abstract

One of the main purposes of SHiP experiment is to shed light on neutrino mass generation mechanisms like the so-called seesaw. We consider a minimal type-I seesaw neutrino mass mechanism model with two heavy neutral leptons (right-handed or sterile neutrinos) with arbitrary masses. Extremely high active-sterile mixing angle requires a correlation between the phases of the Dirac neutrino couplings. Actual experimental limits on the half-life of neutrinoless double beta decay $0\nu\beta\beta$-rate on the active-sterile mixing angle are not significative for SHiP.