Search for the radiative penguin decays B 0 → K 0 S K 0 S γ in the Belle experiment

Abstract

We report results from the first search for the rare penguin-dominated decay mode B 0 → K 0 S K 0 S γ , which can result from the production of tensor mesons f ( 1270 ) and f ′ ( 1525 ) in association with a photon. The search uses the full data sample of 772 × 10 6

B ¯ B pairs collected with the Belle detector at the KEKB asymmetric-energy e + e − collider. No statistically significant signals are observed in the K 0 S K 0 S invariant mass range 1

GeV / c 2 < M K 0 S K 0 S < 3

GeV / c 2 , and the following upper limits at the 90% confidence level are obtained: B ( B 0 → K 0 S K 0 S γ ) < 5.8 × 10 − 7 , B ( B 0 → f 2 γ ) × B ( f 2 ( 1270 ) → K 0 S K 0 S ) < 3.1 × 10 − 7 , and B ( B 0 → f ′ 2 γ ) × B ( f ′ 2 ( 1525 ) → K 0 S K 0 S ) < 2.1 × 10 − 7 . In addition, 90% confidence-level upper limits in the range of [ 0.7 – 2.9 ] × 10 − 7 are also obtained on the B 0 → K 0 S K 0 S γ branching fraction in bins of M K 0 S K 0 S .