Search for the rare decay K+ -> pi+ gamma

Abstract

We have performed a search for the angular-momentum forbidden decay K+ -> pi+ gamma with the E787 detector at BNL. No events were observed in the pi+ kinematic region around 227 MeV/c. An upper limit on the branching ratio for the decay is determined to be 3.6 x 10^{-7} at 90% confidence level.

15 pages, LaTex, 5 figures; revised manuscript, no change in the results, to be published in Physical Review D as a regular article