The electromagnetic polarizabilities of the nucleon are fundamental properties that describe its response to external electric and magnetic fields. They can be extracted from Compton-scattering data—and have been, with good accuracy, in the case of the proton. In contradistinction, information for the neutron requires the use of Compton scattering from nuclear targets. Here, we report a new measurement of elastic photon scattering from deuterium using quasimonoenergetic tagged photons at the MAX IV Laboratory in Lund, Sweden. These first new data in more than a decade effectively double the world data set. Their energy range overlaps with previous experiments and extends it by 20 MeV to higher energies. An analysis using chiral effective field theory with dynamical Δ(1232) degrees of freedom shows the data are consistent with and within the world data set. After demonstrating that the fit is consistent with the Baldin sum rule, extracting values for the isoscalar nucleon polarizabilities, and combining them with a recent result for the proton, we obtain the neutron polarizabilities as αn=[11.55±1.25(stat)±0.2(BSR)±0.8(th)]×10−4 fm3 and βn=[3.65∓1.25(stat)±0.2(BSR)∓0.8(th)]×10−4 fm3, with χ2=45.2 for 44 degrees of freedom.
Digital Object Identifier (DOI)
The Lund group acknowledges the financial support of the Swedish Research Council, the Knut and Alice Wallenberg Foundation, the Crafoord Foundation, the Swedish Institute, the Wenner-Gren Foundation, and the Royal Swedish Academy of Sciences. This material is based upon work supported by the National Science Foundation under Grant No. 0855569; the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No. DE-FG02-93ER40756, No. DE-FG02-95ER40907, and No. DE-FG02-06ER41422; and the UK Science and Technology Facilities Council under Grants No. ST/F012047/1 and No. ST/J000159/1.
Myers, L. S.; Annand, J. R. M.; Brudvik, J.; Feldman, G.; Grießhammer, H. W.; Hansen, K.; Henshaw, S. S.; Isaksson, L.; Jebali, R.; Kovash, Michael A.; Lundin, M.; McGovern, J. A.; Middleton, D. G.; Nathan, A. M.; Phillips, D. R.; Schröder, B.; and Stave, S. C., "Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities" (2014). Physics and Astronomy Faculty Publications. 320.