Limit on neutrinoless ββ decay of 136Xe from the first phase of KamLAND-Zen and comparison with the positive claim in 76Ge.

We present results from the first phase of the KamLAND-Zen double-beta decay experiment, corresponding to an exposure of 89.5 kg yr of (136)Xe. We obtain a lower limit for the neutrinoless double-beta decay half-life of T(1/2)(0ν)>1.