6 NP Nuclear Physics · Verified · ◆◆◆◇◇Difficulty: Research (3 of 5) The Proton Radius Puzzle Muonic-hydrogen spectroscopy measured a proton charge radius several standard deviations smaller than the older electron-scattering and hydrogen-spectroscopy values. Is the… LM Lise Meitner proton-radius muonic-hydrogen spectroscopy qed 6 votes 2 claims posted 3 months ago