论文标题
$ \ varepsilon'/\ varepsilon $在2020年代黎明时的标准模型中
$\varepsilon'/\varepsilon$ in the Standard Model at the Dawn of the 2020s
论文作者
论文摘要
我们使用RBC-UKQCD合作中的最新HADRONIC MATRIX元素在标准模型（SM）中重新分析了比率$ \ VAREPSILON'/\ VAREPSILON $，并结合了最重要的NNLO QCD校正，以进行Electroweak Penguin贡献和Iseospin损坏的校正。我们通过使用手性扰动理论（CHPT）的最新估计来说明后者的重要性，该估计基于$ OCTAT $ $ lif-Lowing Mesons的近似值以及$ NONET $方案的最新估算值，该计划考虑了$η_0$的贡献。我们找到$（\ varepsilon'/\ varepsilon）^{（8）} _ \ text {sm} =（17.4 \ pm 6.1）\ times 10^{ - 4} $和$（\ varepsilon'/\ varepsilon'/\ varepsilon）分别为10^{ - 4} $。尽管与测量值$（\ varepsilon'/\ varepsilon）_ \ text {exp} =（16.6 \ pm 2.3）\ times 10^{ - 4} $相当良好，但在$（\ varepsilon'/\ varepsilon）_ \ varepsilon）_ \ sm sm sm sm sm sm sm vertical for nekial for nekial foragiation {我们为$（\ varepsilon'/\ varepsilon）_ \ text {bsm} $更新2018的主公式（\ varepsilon'/\ varepsilon）。我们提供企鹅参数的新值$ b_6^{（1/2）}（μ）$和$ b_8^{（3/2）}（3/2）}（μ）$在$μ$ -SCALES使用的$μ$ -SCALES，由RBC-UKQCD合作和较低的Scales $ \ Mathcal $ \ Mathcal {O} $ chpt and c \ by c \ f chst and c \ f text {我们为$（\ varepsilon'/\ varepsilon）提供半分析公式，以这些参数为例，$ \hatΩ_\ text {eff} $汇总了Isospin-Break-Break-Breaking-Breaking校正的比率。我们强调了$ \ MATHCAL {O}（α__\ text {em}）$对$ \ Mathcal {o}（α__\ text {em}）$ v vareps $ \ v v v v y \ v \ v \ v \ v v y \ v v v y \ v \ v v v y \ v v v v y的重要性的重要性。
We reanalyse the ratio $\varepsilon'/\varepsilon$ in the Standard Model (SM) using most recent hadronic matrix elements from the RBC-UKQCD collaboration in combination with most important NNLO QCD corrections to electroweak penguin contributions and the isospin-breaking corrections. We illustrate the importance of the latter by using their latest estimate from chiral perturbation theory (ChPT) based on the $octet$ approximation for lowest-lying mesons and a very recent estimate in the $nonet$ scheme that takes into account the contribution of $η_0$. We find $(\varepsilon'/\varepsilon)^{(8)}_\text{SM} = (17.4 \pm 6.1) \times 10^{-4}$ and $(\varepsilon'/\varepsilon)^{(9)}_\text{SM} = (13.9 \pm 5.2) \times 10^{-4}$, respectively. Despite a very good agreement with the measured value $(\varepsilon'/\varepsilon)_\text{exp} = (16.6 \pm 2.3) \times 10^{-4}$, the large error in $(\varepsilon'/\varepsilon)_\text{SM}$ still leaves room for significant new physics (BSM) contributions to this ratio. We update the 2018 master formula for $(\varepsilon'/\varepsilon)_\text{BSM}$ valid in any extension beyond the SM without additional light degrees of freedom. We provide new values of the penguin parameters $B_6^{(1/2)}(μ)$ and $B_8^{(3/2)}(μ)$ at the $μ$-scales used by the RBC-UKQCD collaboration and at lower scales $\mathcal{O}(1\,\text{GeV})$ used by ChPT and DQCD. We present semi-analytic formulae for $(\varepsilon'/\varepsilon)_\text{SM}$ in terms of these parameters and $\hatΩ_\text{eff}$ that summarizes isospin-breaking corrections to this ratio. We stress the importance of lattice calculations of the $\mathcal{O}(α_\text{em})$ contributions to the hadronic matrix elements necessary for the removal of renormalization scheme dependence at $\mathcal{O}(α_\text{em})$ in the present analyses of $\varepsilon'/\varepsilon$.
