Observation of the decay K- --> pi(-)mu(+)mu(-) and measurements of the branching ratios for K+/- --> pi(+/-)mu(+)mu(-).
Using data collected with the HyperCP (E871) spectrometer during the 1997 fixed-target run at Fermilab, we report the first observation of the decay K--->pi(-)mu(+)mu(-) and new measurements of the branching ratios for K+/--->pi(+/-)mu(+)mu(-). By combining the branching ratios for the decays K+-->pi(+)mu(+)mu(-) and K--->pi(-)mu(+)mu(-), we measure Gamma(K+/--->pi(+/-)mu(+)mu(-))/Gamma(K+/--->all) = (9.8+/-1.0+/-0.5)x10(-8). The CP asymmetry between the rates of the two decay modes is [Gamma(K+-->pi(+)mu(+)mu(-))-Gamma(K--->pi(-)mu(+)mu(-))]/[Gamma(K+-->pi(+)mu(+)mu(-))+Gamma(K--->pi(-)mu(+)mu(-))] = -0.02+/-0.11+/-0.04.
Park
H K
HK
University of Michigan, Ann Arbor, Michigan 48109, USA.
Burnstein
R A
RA
Chakravorty
A
A
Chan
A
A
Chen
Y C
YC
Choong
W S
WS
Clark
K
K
Dukes
E C
EC
Durandet
C
C
Felix
J
J
Gidal
G
G
Gu
P
P
Gustafson
H R
HR
Ho
C
C
Holmstrom
T
T
Huang
M
M
James
C
C
Jenkins
C M
CM
Kaplan
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Lederman
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LM
Leros
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N
Longo
M J
MJ
Lopez
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F
Lu
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L
Luebke
W
W
Luk
K B
KB
Nelson
K S
KS
Perroud
J P
JP
Rajaram
D
D
Rubin
H A
HA
Teng
P K
PK
Volk
J
J
White
C
C
White
S
S
Zyla
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P