title: Improved branching ratio measurement for the decay K(0)(L) --> &mgr;(+)&mgr;(-)
abstract: We report results from Experiment 871, performed at the BNL AGS, of a measurement of the branching ratio K(0)(L)-->&mgr;(+)&mgr;(-) with respect to the CP-violating mode K(0)(L)-->pi(+)pi(-). This experiment detected over 6200 candidate &mgr;(+)&mgr;(-) events, a factor of 6 more than that seen in all previous measurements combined. The resulting branching ratio gamma(K(0)(L)-->&mgr;(+)&mgr;(-))/gamma(K(0)(L)-->pi(+)pi(-)) = (3. 474+/-0.057)x10(-6) leads to a branching fraction B(K(0)(L)-->&mgr;(+)&mgr;(-)) = (7.18+/-0.17)x10(-9), which is consistent with the current world average, and reduces the uncertainty in this decay mode by a factor of 3.
authors.affiliation: University of Texas, Austin, Texas 78712, USA.
authors.initials: D
authors.lastname: Ambrose
authors.initials: C
authors.lastname: Arroyo
authors.initials: M
authors.lastname: Bachman
authors.initials: D
authors.lastname: Connor
authors.initials: M
authors.lastname: Eckhause
authors.initials: S
authors.lastname: Graessle
authors.initials: AD
authors.lastname: Hancock
authors.initials: K
authors.lastname: Hartman
authors.initials: M
authors.lastname: Hebert
authors.initials: CH
authors.lastname: Hoff
authors.initials: GW
authors.lastname: Hoffmann
authors.initials: GM
authors.lastname: Irwin
authors.initials: JR
authors.lastname: Kane
authors.initials: N
authors.lastname: Kanematsu
authors.initials: Y
authors.lastname: Kuang
authors.initials: K
authors.lastname: Lang
authors.initials: R
authors.lastname: Lee
authors.initials: RD
authors.lastname: Martin
authors.initials: J
authors.lastname: McDonough
authors.initials: A
authors.lastname: Milder
authors.initials: WR
authors.lastname: Molzon
authors.initials: M
authors.lastname: Pommot-Maia
authors.initials: PJ
authors.lastname: Riley
authors.initials: JL
authors.lastname: Ritchie
authors.initials: PD
authors.lastname: Rubin
authors.initials: VI
authors.lastname: Vassilakopoulos