### Abstract

We study Compton scattering in systems with A = 1 and 2 using chiral perturbation theory up to fourth order. For the proton we fit the two undetermined parameters in the O(Q^{4}) γp amplitude of McGovern to experimental data in the region ω, t ≤ 180 MeV, obtaining a χ^{2} /d.o.f. of 133/113. This yields a model-independent extraction of proton polarizabilities based solely on low-energy data: α_{p} = (12.1 ± 1.1 (stat.)) _{-0.5} ^{+0.5} (theory) and β_{p} = (3.4 ± 1.1 (stat.))_{-0.1} ^{+0.1} (theory), both in units of 10^{-4} fm^{3}. We also compute Compton scattering on deuterium to O(Q^{4}). The γd amplitude is a sum of one- and two-nucleon mechanisms, and contains two undetermined parameters, which are related to the isoscalar nucleon polarizabilities. We fit data points from three recent γd scattering experiments with a χ^{2} /d.o.f. = 26.6/20, and find α_{N} = (13.0 ± 1.9 (stat.))_{-1.5} ^{+3.9} (theory) and a β_{N} that is consistent with zero within sizable error bars.

Original language | English (US) |
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Pages (from-to) | 311-361 |

Number of pages | 51 |

Journal | Nuclear Physics A |

Volume | 747 |

Issue number | 2-4 |

DOIs | |

State | Published - Jan 24 2005 |

### ASJC Scopus subject areas

- Nuclear and High Energy Physics

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## Cite this

^{4}).

*Nuclear Physics A*,

*747*(2-4), 311-361. https://doi.org/10.1016/j.nuclphysa.2004.09.068