Dispersion theory of nucleon polarizabilities and outlook on chiral effective field theory

Abstract

Based on Compton scattering and meson photoproduction data the polarizabilities of the nucleon are precisely studied and well understood due to recent experimental and theoretical work based on nonsubtracted dispersion relations. The {\it recommended} experimental values are ${\alpha }_p=12.0\pm 0.6$, $(12.0)$, ${\beta }_p=1.9\mp 0.6$, $(1.9)$, ${\alpha }_n=12.5\pm 1.7$, $(12.7\pm 0.9)$, ${\beta }_n=2.7\mp 1.8$, $(2.5\mp 0.9)$ in units of $10^{-4}$fm${}^3$ and ${\gamma }_{\pi }^{(p)}=-36.4\pm 1.5$, $(-36.6)$, ${\gamma }_{\pi }^{(n)}=+58.6\pm 4.0$, $(58.3)$, $({\gamma }_0^{(p)}=-0.58\pm 0.20)$, ${\gamma }_0^{(n)}=0.38\pm 0.22)$ in units of $10^{-4}$fm${}^4$ [1]. The numbers given in parentheses are predicted values. It is shown that all versions of chiral effective field theories applied in analyses of nucleon polarizabilities and Compton scattering ignore essential effects of $\omega$, $\rho$ and $\sigma$ exchanges and of pseudoscalar $\pi$N coupling.

Contribution prepared for the workshop "Compton scattering off Protons and Light Nuclei pinning down the nucleon polarizabilities" ETC* Trento Italy, July 29 . Aug. 2,2013

References in corpus (6)

• Compton scattering from the proton in an effective field theory with explicit Delta degrees of freedom
• Separation of proton polarizabilities with the beam asymmetry of Compton scattering
• What different variants of chiral EFT predict for the proton Compton differential cross section - and why
• The Quark-Level Linear σ Model
• Dispersion theory of nucleon Compton scattering and polarizabilities
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