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

• Published in: Physical review letters Vol. 88; no. 11; p. 111801
• Main Authors: Park, H K, Burnstein, R A, Chakravorty, A, Chan, A, Chen, Y C, Choong, W S, Clark, K, Dukes, E C, Durandet, C, Felix, J, Gidal, G, Gu, P, Gustafson, H R, Ho, C, Holmstrom, T, Huang, M, James, C, Jenkins, C M, Kaplan, D M, Lederman, L M, Leros, N, Longo, M J, Lopez, F, Lu, L, Luebke, W, Luk, K B, Nelson, K S, Perroud, J P, Rajaram, D, Rubin, H A, Teng, P K, Volk, J, White, C, White, S, Zyla, P
• Format: Journal Article
• Language: English
• Published: United States 18-03-2002
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.88.111801

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.