Light Sterile Neutrinos, Left-Right Symmetry, and 0νββ Decay*

We investigate neutrinoless double beta (0νββ) decay rates in minimal left-right symmetric models in the presence of relatively light right-handed neutrinos. Using an effective field theory approach, we systematically include all contributions in the model as well as the dependence of the decay amplitude on the masses of right-handed neutrinos. In type-I and type-II seesaw scenarios, we analyze the impact of right-handed neutrinos heavier than about 10 MeV, showing that this effect can lead to a detection of 0νββ decay in the next-generation experiments even for the normal hierarchy and a relatively large right-handed scale set by the mass of hypothetical right-handed gauge bosons. Finally, we comment on a possible connection between light right-handed neutrinos and the strong CP problem.