Electromagnetic polarizabilities and the excited states of the nucleon

Martin Schumacher

doi:10.1140/epja/i2006-10235-1

paper

Electromagnetic polarizabilities and the excited states of the nucleon

arXiv:0704.0200 · doi:10.1140/epja/i2006-10235-1

Abstract

The electromagnetic polarizabilities of the nucleon are shown to be essentially composed of the nonresonant $α_{p} (E_{0 +}) = + 3.2$ , $α_{n} (E_{0 +}) = + 4.1$ ,the $t$ -channel $α_{p, n}^{t} = - β_{p, n}^{t} = + 7.6$ and the resonant $β_{p, n} (P_{33} (1232)) = + 8.3$ contributions (in units of $1 0^{- 4}$ fm $^{3}$ . The remaining deviations from the experimental data $Δ α_{p} = 1.2 \pm 0.6$ , $Δ β_{p} = 1.2 \mp 0.6$ , Δα_n=0.8\pm 1.7 $an d$ Δβ_n=2.0\mp 1.8 $a r eco n t r ib u t e d b y a l a r g er n u mb er o f r eso nan t an d n o n r eso nan tp r ocesses w i t h c an ce l l a t i o n s b e tw ee n t h eco n t r ib u t i o n s . T hi sr es u l t co n f i r m s t ha t d o minan t co n t r ib u t i o n s t o t h ee l ec t r i c an d ma g n e t i c p o l a r i z abi l i t i es ma y b er e p r ese n t e d in t er m so f tw o - p h o t o n co u pl in g s t o t h e$ σ $- m eso nha v in g t h e p r e d i c t e d ma ss$ m_σ=666 $M e V an d tw o - p h o t o n w i d t h$ Γ_{γγ}=2.6$ keV.

Electromagnetic polarizabilities and the excited states of the nucleon

Abstract

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