The 1S hyperfine splitting in hydrogen is measured to an impressive ppt precision and will soon be measured to ppm precision in muonic hydrogen. The latter measurement will rely on theoretical predictions, which are limited by knowledge of the proton polarizability effect Δpol. Data-driven evaluations of Δpol have long been in significant tension with baryon chiral perturbation theory. Here we present improved results for Δpol driven by new spin structure data, reducing the long-standing tension between theory and experiment and halving the dominating uncertainty in hyperfine splitting calculations.

中文翻译：

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超精细分裂和质子 Zemach 半径的新自旋结构约束


氢中的 1S 超精细分裂测量精度令人印象深刻，很快将在 μ 子氢中测量到 ppm 精度。后一种测量将依赖于理论预测，而理论预测受到质子极化效应 Δpol 知识的限制。长期以来，Δpol 的数据驱动评估一直与重子手性扰动理论存在重大冲突。在这里，我们提出了由新的自旋结构数据驱动的 Δpol 的改进结果，减少了理论与实验之间长期存在的紧张关系，并将超精细分裂计算中的主要不确定性减半。