Brod Joachim, Gorbahn Martin, Stamou Emmanuel
Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221, USA.
Department of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL, United Kingdom.
Phys Rev Lett. 2020 Oct 23;125(17):171803. doi: 10.1103/PhysRevLett.125.171803.
The parameter ε_{K} describes CP violation in the neutral kaon system and is one of the most sensitive probes of new physics. The large uncertainties related to the charm-quark contribution to ε_{K} have so far prevented a reliable standard-model prediction. We show that Cabibbo-Kobayashi-Maskawa unitarity enforces a unique form of the |ΔS=2| weak effective Lagrangian in which the short-distance theory uncertainty of the imaginary part is dramatically reduced. The uncertainty related to the charm-quark contribution is now at the percent level. We present the updated standard-model prediction ε_{K}=2.16(6)(8)(15)×10^{-3}, where the errors in parentheses correspond to QCD short-distance, long-distance, and parametric uncertainties, respectively.
参数εₖ描述了中性K介子系统中的CP破坏，并且是新物理最灵敏的探针之一。到目前为止，与粲夸克对εₖ的贡献相关的巨大不确定性阻碍了可靠的标准模型预测。我们表明，卡比博-小林-益川（Cabibbo-Kobayashi-Maskawa）幺正性强制|ΔS = 2|弱有效拉格朗日量具有一种独特形式，其中虚部的短程理论不确定性显著降低。与粲夸克贡献相关的不确定性现在处于百分之几的水平。我们给出更新后的标准模型预测值εₖ = 2.16(6)(8)(15)×10⁻³，其中括号内的误差分别对应于量子色动力学（QCD）短程、长程和参数不确定性。
