论文标题
$ \ varepsilon'/\ varepsilon $：$η_0$的影响在2020年代黎明时的影响
Isospin-breaking in $\varepsilon'/\varepsilon$: Impact of $η_0$ at the Dawn of the 2020s
论文作者
论文摘要
对于$ k \toππ$衰减中的直接CP侵略，百分比级别的普通issospin破坏效果会被$ΔI= 1/2 $规则的动态放大，并且常规编码为$ω_{\ rm Ib ib ib} $参数。更新的预测$ω_ {\ rm ib}^{（8）} =（15.9 \ pm 8.2）\ times 10^{ - 2} $的手性扰动理论对强烈的issospin threking for $π_3-η_8$混合所导致的趋势是相当敏感的，但对敏感的趋势确认了构成的敏感性，该趋势是有价值的，有价值的有价值，该趋势是有效的。 flavour-singlet $η_0$在此截断的八位章方案中交换捐款。 We rather exploit the phenomenological $η_8-η_0$ mixing as a probe for the non-negligible flavour-singlet component of the physical $η$ pole to find $Ω_{\rm IB}^{(9)}=(35\pm7)\times 10^{-2}$ in a complete nonet scheme.因此，非ET方案中的一个大中心值被替代了八位位置中的较大不确定性。包括实验性$π^+-π^0 $质量差为主要的电磁等异种破裂，我们获得了输入比率$ε'/ε$的有效参数，改进的结果$ \hatΩ_{\ rm eff} $ \hatΩ_ {\ rm eff}^{（8）} =（17 \ pm9）\ times 10^{ - 2} $在最近分析的$ε'/ε$中使用。因此，我们从$（ε'/ε）_ {\ rm sm}^{（8）} =（17.4 \ pm 6.1）\ times 10^{ - 4} $到$（ε'/ε）_ {\ rm sm}^（9）=（9）} =（9.9）=（13.9 $ 5.2）相对于最近的RBC-UKQCD值，通过ISOSPIN破坏校正对$（ε'/ε）_ {\ rm sm} $的抑制。
For direct CP-violation in $K\toππ$ decays, the usual isospin-breaking effects at the percent level are amplified by the dynamics behind the $ΔI=1/2$ rule and conventionally encoded in $Ω_{\rm IB}$ parameters. The updated prediction $Ω_{\rm IB}^{(8)}=(15.9\pm 8.2)\times 10^{-2}$ of the Chiral Perturbation Theory for the strong isospin-breaking due to $π_3-η_8$ mixing confirms such a tendency but is quite sensitive to the theoretical input value of the low-energy constant corresponding to the flavour-singlet $η_0$ exchange contribution in this truncated octet scheme. We rather exploit the phenomenological $η_8-η_0$ mixing as a probe for the non-negligible flavour-singlet component of the physical $η$ pole to find $Ω_{\rm IB}^{(9)}=(35\pm7)\times 10^{-2}$ in a complete nonet scheme. A large central value in the nonet scheme is thus substituted for a large uncertainty in the octet one. Including the experimental $π^+-π^0$ mass difference as the dominant electromagnetic isospin-breaking, we obtain for the effective parameter entering the ratio $ε'/ε$ an improved result $\hatΩ_{\rm eff}^{(9)}=(29\pm7)\times 10^{-2}$ to be compared with $\hatΩ_{\rm eff}^{(8)}=(17\pm9)\times 10^{-2}$ used in recent analyses of $ε'/ε$. Accordingly, we get a reduction from $(ε'/ε)_{\rm SM}^{(8)}=(17.4\pm 6.1)\times 10^{-4}$ to $(ε'/ε)_{\rm SM}^{(9)}=(13.9\pm 5.2)\times 10^{-4}$ and thereby an effective suppression of $(ε'/ε)_{\rm SM}$ by isospin-breaking corrections as large as $40\%$ relative to the recent RBC-UKQCD value.
