Oklo对$α$变异限度的再评价
Reappraisal of the limit on the variation in $α$ implied by Oklo
摘要：
我们重新考虑中子共振能量$E_i$的$α$的变化的敏感性分析，以解决困扰早期治疗的不确定性。我们指出，更适当的选择核参数，标准估计（由于达穆尔和戴森）的灵敏度共振${}^{150}$钐增加了2.5倍。我们继续识别和计算激励，库仑和变形校正。为此，我们使用变形费米密度分布拟合的输出Hartree-Fock（HF）+ BCS计算（与SLy 4和SkM $^*$ Skyrme泛函），能量的表面扩散的核，和热性质的变形。我们还调用本征态热化假设，执行必要的微正则平均值与两个唯象的水平密度，通过leptodermous扩展的水平密度参数，包括增加表面扩散的效果。理论上的不确定性用Dobaczewski等人的\emph{inter-model}公式[J. Phys. G：Nucl. Part. { \bf 41}，074001（2014）]。校正降低了修订后的${}^{150}$ Sm灵敏度，但不超过25%。由于对自Oklo反应堆活跃以来$m_q/Λ$的变化（相对于$α$的变化）有一个弱的和可测试的限制（$m_q$是$\text{u}$和$\text{d}$当前夸克质量的平均值，$Λ$是量子色动力学的质量标度），我们推断出$|α_{\text{Oklo}}-α_{\text{now}}|<1.1\times 10^{-8}α_{\text{now}}$（95\%置信水平）。目前$α$的时间变化的相应界限比原子钟实验迄今为止的最佳界限更紧。
英文摘要：
We reconsider the analysis of the sensitivity of neutron resonance energies $E_i$ to changes in $α$ with a view to resolving uncertainties that plague earlier treatments. We point out that, with more appropriate choices of nuclear parameters, the standard estimate (due to Damour and Dyson) of the sensitivity for resonances in ${}^{150}$Sm is increased by a factor of 2.5. We go on to identify and compute excitation, Coulomb and deformation corrections. To this end, we use deformed Fermi density distributions fitted to the output of Hartree-Fock (HF) + BCS calculations (with both the SLy4 and SkM$^*$ Skyrme functionals), the energetics of the surface diffuseness of nuclei, and thermal properties of their deformation. We also invoke the eigenstate thermalization hypothesis, performing the requisite microcanonical averages with two phenomenological level densities which, via the leptodermous expansion of the level density parameter, include the effect of increased surface diffuseness. Theoretical uncertainties are assessed with the \emph{inter-model} prescription of Dobaczewski et al. [J. Phys. G: Nucl. Part. Phys. {\bf 41}, 074001 (2014)]. The corrections diminish the revised ${}^{150}$Sm sensitivity but not by more than 25\%. Subject to a weak and testable restriction on the change in $m_q/Λ$ (relative to the change in $α$) since the time when the Oklo reactors were active ($m_q$ is the average of the $\text{u}$ and $\text{d}$ current quark masses, and $Λ$ is the mass scale of quantum chromodynamics), we deduce that $|α_{\text{Oklo}}-α_{\text{now}}|<1.1\times 10^{-8}α_{\text{now}}$ (95\% confidence level). The corresponding bound on the present-day time variation of $α$ is tighter than the best limit to date from atomic clock experiments.
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