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
University of Michigan, Ann Arbor, Michigan 48109, USA.
Phys Rev Lett. 2002 Mar 18;88(11):111801. doi: 10.1103/PhysRevLett.88.111801. Epub 2002 Feb 28.
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.
利用1997年费米实验室固定靶运行期间使用HyperCP（E871）光谱仪收集的数据，我们首次观测到了K⁻→π⁻μ⁺μ⁻衰变，并对K⁺/⁻→π⁺/⁻μ⁺μ⁻的分支比进行了新的测量。通过结合K⁺→π⁺μ⁺μ⁻和K⁻→π⁻μ⁺μ⁻衰变的分支比，我们测得Γ(K⁺/⁻→π⁺/⁻μ⁺μ⁻)/Γ(K⁺/⁻→所有衰变) = (9.8±1.0±0.5)×10⁻⁸。两种衰变模式速率之间的CP不对称性为[Γ(K⁺→π⁺μ⁺μ⁻) - Γ(K⁻→π⁻μ⁺μ⁻)]/[Γ(K⁺→π⁺μ⁺μ⁻) + Γ(K⁻→π⁻μ⁺μ⁻)] = -0.02±0.11±0.04。
