• DOI:10.1126/science.aaf2468
• Corpus ID: 206647315

Laser spectroscopy of muonic deuterium

@article{Pohl2016LaserSO,
  title={Laser spectroscopy of muonic deuterium},
  author={Randolf Pohl and François Nez and Luis M P Fernandes and Fernando Domingues Amaro and Francois Biraben and Jo{\~a}o M. R. Cardoso and Daniel S. Covita and Andreas J Dax and S. K. Dhawan and Marc Diepold and Adolf Giesen and Andrea L. Gouvea and Thomas Graf and Theodor W. H{\"a}nsch and Paul Indelicato and Lucile Julien and Paul E. Knowles and Franz Kottmann and E-O Le Bigot and Yi-Wei Liu and Jos{\'e} A. M. Lopes and Livia Ludhova and Cristina Maria Bernardes Monteiro and Françoise Mulhauser and Tobias Nebel and Paul Rabinowitz and Joaquim Marques Ferreira dos Santos and Lukas A. Schaller and Karsten Schuhmann and Catherine Schwob and David Taqqu and Jo{\~a}o Veloso and Aldo Antognini},
  journal={Science},
  year={2016},
  volume={353},
  pages={669 - 673}
}

• R. Pohl, F. Nez, +30 authors A. Antognini
• Published 12 August 2016
• Physics
• Science

The deuteron is too small, too The radius of the proton has remained a point of debate ever since the spectroscopy of muonic hydrogen indicated a large discrepancy from the previously accepted value. Pohl et al. add an important clue for solving this so-called proton radius puzzle. They determined the charge radius of the deuteron, a nucleus consisting of a proton and a neutron, from the transition frequencies in muonic deuterium. Mirroring the proton radius puzzle, the radius of the deuteron was several standard deviations smaller than the value inferred from previous spectroscopic measurements of electronic deuterium. This independent discrepancy points to experimental or theoretical error or even to physics beyond the standard model. Science, this issue p. 669 The charge radius of the deuteron is several standard deviations smaller than the previously accepted value. The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron properties such as the root-mean-square charge radius rd and the polarizability serve as important benchmarks for understanding the nuclear forces and structure. Muonic deuterium μd is the exotic atom formed by a deuteron and a negative muon μ–. We measured three 2S-2P transitions in μd and obtain rd = 2.12562(78) fm, which is 2.7 times more accurate but 7.5σ smaller than the CODATA-2010 value rd = 2.1424(21) fm. The μd value is also 3.5σ smaller than the rd value from electronic deuterium spectroscopy. The smaller rd, when combined with the electronic isotope shift, yields a “small” proton radius rp, similar to the one from muonic hydrogen, amplifying the proton radius puzzle.