Searches for double beta decay of Xe134 with EXO-200

Searches for double beta decay of ^(134)Xe were performed with EXO-200, a single-phase liquid xenon detector designed to search for neutrinoless double beta decay of ^(136)Xe. Using an exposure of 29.6 kg⋅yr, the lower limits of T^(2νββ_+(1/2) > 8.7×10^(20) yr and T^(0νββ)_(1/2) > 1.1×10^(23) yr at 90% confidence level were derived, with corresponding half-life sensitivities of 1.2×10^(21) yr and 1.9×10^(23) yr. These limits exceed those in the literature for ^(134)Xe, improving by factors of nearly 105 and 2 for the two antineutrino and neutrinoless modes, respectively.