English

New Spin Structure Constraints on Hyperfine Splitting and Proton Size

Nuclear Experiment 2024-09-04 v2 Nuclear Theory Atomic Physics

Abstract

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\Delta_\text{pol}. Data-driven evaluations of Δpol\Delta_\text{pol} have long been in significant tension with baryon chiral perturbation theory. Here we present improved results for Δpol\Delta_\text{pol} driven by new spin structure data, reducing the long-standing tension between theory and experiment and halving the dominating uncertainty in hyperfine splitting calculations.

Keywords

Cite

@article{arxiv.2406.18738,
  title  = {New Spin Structure Constraints on Hyperfine Splitting and Proton Size},
  author = {David Ruth and Karl Slifer and Jian-Ping Chen and Carl E. Carlson and Franziska Hagelstein and Vladimir Pascalutsa and Alexandre Deur and Sebastian Kuhn and Marco Ripani and Xiaochao Zheng and Ryan Zielinski and Chao Gu},
  journal= {arXiv preprint arXiv:2406.18738},
  year   = {2024}
}
R2 v1 2026-06-28T17:20:33.534Z