Physical Review D 75,3 (2007)
We present a measurement of the branching fraction of invisible Y(1S) decays, using 1.2 fb(-1) of data collected at the Y(2S) resonance with the CLEO III detector at CESR. After subtracting expected backgrounds from events that pass selection criteria for invisible Y(1S) decay in Y(2S) -> pi(+) pi(-) Y(1S), we deduce a 90% C. L. upper limit of B[Y(1S) -> invisible] < 0.39%.
Astronomy & Astrophysics;; Physics, Particles & Fields
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