Tuesday, July 9, 2013

1307.2215 (Martin Schumacher)

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

Martin Schumacher
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 $\gamma^{(p)}_\pi=-36.4\pm 1.5$, $(-36.6)$, $\gamma^{(n)}_\pi=+58.6\pm 4.0$, $(58.3)$, $(\gamma^{(p)}_0=-0.58\pm 0.20)$, $\gamma^{(n)}_0=0.38\pm 0.22)$ in units of $10^{-4}$fm$^4$ [1]. The numbers given in parentheses are predicted values. Recently attempts to reanalyse low-energy Compton scattering data by making use of different versions of chiral effective field theory ($\chi$EFT) have led to sizable discrepancies between each other and with the {\it recommended} experimental data. An investigation is presented showing that these newly analyzed data should not be included in the {\it recommendation}.
View original: http://arxiv.org/abs/1307.2215

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