Unparticle effects on neutrinoless and neutrino double beta decay

The neutrinoless and neutrinos double beta decays are investigated in an effective theory where a scalar unparticle is introduced. We calculate the contributions of a virtual unparticle to the rates of 0ν2β and 2ν2β decays. The unparticle effect is negligibly small when the scaling dimension d of unparticle lies in the region 1.1-1.9. But it can be relatively large when d approaches to 1 or 2. We also study the neutrinoless double beta decay with a real unparticle in the final state which cannot be distinguished from 2ν2β decay in experiment. We consider the unparticle effect on extracting the neutrino mass parameter mββ from experimental data and find that it can be relatively large when d takes certain values.