Observation of the decay K- --> pi(-)mu(+)mu(-) and measurements of the branching ratios for K+/- --> pi(+/-)mu(+)mu(-)

H K Park; R A Burnstein; A Chakravorty; A Chan; Y C Chen; W S Choong; K Clark; E C Dukes; C Durandet; J Felix; G Gidal; P Gu; H R Gustafson; C Ho; T Holmstrom; M Huang; C James; C M Jenkins; D M Kaplan; L M Lederman; N Leros; M J Longo; F Lopez; L Lu; W Luebke; K B Luk; K S Nelson; J P Perroud; D Rajaram; H A Rubin; P K Teng; J Volk; C White; S White; P Zyla; HyperCP Collaboration

doi:10.1103/PhysRevLett.88.111801

Observation of the decay K- --> pi(-)mu(+)mu(-) and measurements of the branching ratios for K+/- --> pi(+/-)mu(+)mu(-)

Phys Rev Lett. 2002 Mar 18;88(11):111801. doi: 10.1103/PhysRevLett.88.111801. Epub 2002 Feb 28.

Authors

Affiliation

¹ University of Michigan, Ann Arbor, Michigan 48109, USA.

PMID: 11909394
DOI: 10.1103/PhysRevLett.88.111801

Abstract

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.