New measurement of the rare decay K+ --> pi(+)&mgr;(+)&mgr;(-)
More than 400 K+-->pi(+)&mgr;(+)&mgr;(-) events were observed in a rare K+ decay experiment at the Brookhaven Alternating Gradient Synchrotron. Normalized to the K+-->pi(+)pi(+)pi(-) decay, the branching ratio is determined to be [9.22+/-0.60(stat)+/-0. 49(syst)]x10(-8). This branching ratio and the &mgr;&mgr; mass spectrum is in very good agreement with the measurement of the K+-->pi(+)e(+)e(-) decay, but deviates significantly from the previous measurement.
Ma
H
Brookhaven National Laboratory, Upton, New York 11973, USA.
Appel
R
Atoyan
GS
Bassalleck
B
Bergman
DR
Cheung
N
Dhawan
S
Do
H
Egger
J
Eilerts
S
Fischer
H
Herold
W
Issakov
VV
Kaspar
H
Kraus
DE
Lazarus
DM
Lichard
P
Lowe
J
Lozano
J
Majid
W
Menzel
W
Pislak
S
Poblaguev
AA
Rehak
P
Sher
A
Thompson
JA