This figure shows the analyzing power differences in elastic np scattering measured at TRIUMF [1,2] and IUCF [3]. The solid error bars reflect the statistical uncertainty and the dashed extensions the statistical and systematic uncertainties added in quadrature.

The calculations are by Iqbal and Niskanen [4] and Holzenkamp, Holinde, and Thomas [5]. The short dashed lines () are when only the electromagnetic contribution due to one photon exchange is considered; when the contribution due to the np mass difference in one boson exchange is included these calculations give values shown by the long dashed lines (, , and ). Including the contribution due to the exchange of a mixed meson are gives the solid lines (, , , and ). Clearly these models require the inclusion of mixing to describe the data at 183 MeV.


[1]
R. Abegg, et al. , Phys. Rev. Let. 56, 2571 (1986); Phys. Rev. D 39, 2464 (1989).

[2]
R. Abegg, et al. , Phys. Rev. Let. 75, 1711 (1995).

[3]
S.E. Vigdor, et al. , Phys. Rev. C 46, 410 (1992).

[4]
M.J. Iqbal and J.A. Niskanen, Phys. Rev. C 38, 2259 (1988).

[5]
B. Holzenkamp, K. Holinde, and G.A. Miller, Phys. Lett. B 195, 121 (1987).



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Richard T. Waters
28 August 1996