Abstract
We report the results of the first search for the decay B0s
→ π0π0 using 121.4 fb−1 of data collected at the
ϒð5SÞ resonance with the Belle detector at the KEKB asymmetric-energy eþe− collider. We observe no signal and set a 90% confidence level upper limit of 7.7 × 10−6 on the B0s
→ π0π0 decay branching fraction.