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arXiv 2203.01972nucl-th
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用有效场论和贝叶斯方法分析奇质量核转动带

Analyzing rotational bands in odd-mass nuclei using Effective Field Theory and Bayesian methods

I. K. Alnamlah, E. A. Coello Pérez, D. R. Phillips

摘要:

我们最近发展了奇质量核转动带的有效场论。在这里,我们使用EFT表达式对$^{99}$ Tc、${}^{155,157}$ Gd、${}^{159}$ Dy、${}^{167, 169}$ Er、${}^{167, 169}$ Tm、${}^{183}$ W、${}^{235}$ U和${}^{239}$ Pu的转动能级数据进行贝叶斯分析。在我们的贝叶斯分析的误差模型包括实验和EFT截断不确定性。它还解释了这样一个事实,即偶数阶和奇数阶的低能常数(LEC)预计具有不同的大小。我们使用马尔可夫链蒙特卡罗(MCMC)抽样,探索联合后验的EFT和误差模型参数,并显示LEC和扩展参数,$Q$,可以可靠地确定。我们提取的LEC四阶EFT,并发现,只要我们正确地考虑EFT截断误差在我们的可能性,结果为低阶LEC是稳定的,因为我们去高阶。LEC的结果也是稳定的,相对于添加更高的能量数据。我们提取了上述所有原子核的膨胀参数,并根据单粒子和振动能量标度找到了提取的和预期的$Q$之间的明确相关性。然而,实际上决定EFT展开收敛的$Q$明显小于基于这些尺度的天真预期。

英文摘要:

We recently developed an Effective Field Theory (EFT) for rotational bands in odd-mass nuclei. Here we use EFT expressions to perform a Bayesian analysis of data on the rotational energy levels of $^{99}$Tc, ${}^{155,157}$Gd, ${}^{159}$Dy, ${}^{167, 169}$Er, ${}^{167, 169}$Tm, ${}^{183}$W, ${}^{235}$U and ${}^{239}$Pu. The error model in our Bayesian analysis includes both experimental and EFT truncation uncertainties. It also accounts for the fact that low-energy constants (LECs) at even and odd orders are expected to have different sizes. We use Markov Chain Monte Carlo (MCMC) sampling to explore the joint posterior of the EFT and error-model parameters and show both the LECs and the expansion parameter, $Q$, can be reliably determined. We extract the LECs up to fourth order in the EFT and find that, provided we correctly account for EFT truncation errors in our likelihood, results for lower-order LECs are stable as we go to higher orders. LEC results are also stable with respect to the addition of higher-energy data. We extract the expansion parameter for all the nuclei listed above and find a clear correlation between the extracted and the expected $Q$ based on the single-particle and vibrational energy scales. However, the $Q$ that actually determines the convergence of the EFT expansion is markedly smaller than would be naively expected based on those scales.

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