Neutrino Mass Sum-rule and Neutrinoless Double Beta Decay

Neutrino mass sum-rule is a very important research subject from theoretical side because neutrino oscillation experiment only gave us two squared-mass differences and three mixing angles. We review neutrino mass sum-rule in literature that have been reported by many authors and discuss its phenomenological implications especially on neutrino mass and neutrinoless double beta decay by plotting effective Majorana mass $<m_{ee}>$ as function of the lightest neutrino mass both for normal and inverted hierarchy by using the central values of reported mixing angles and reported squared-mass differences as input