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arXiv · 0811.3539

Contribution of Two-Boson-Exchange with $Δ(1232)$ Excitation to Parity-Violating Elastic Electron-Proton Scattering

Keitaro Nagata·Hai Qing Zhou·Chung Wen Kao·Shin Nan Yang
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Abstract

We study the leading electroweak corrections in the precision measurement of the strange form factors. Specifically, we calculate the two-boson-exchange (TBE), two-photon-exchange (TPE) plus $γZ$-exchange ($γZ$E), corrections with $Δ(1232)$ excitation to the parity-violating asymmetry of the elastic electron-proton scattering. The interplay between nucleon and $Δ$ contributions is found to depend strongly on the kinematics, as $δ_Δ$ begins as negligible at backward angles but becomes very large and negative and dominant at forward angles, while $δ_N$ always stays positive and decreases monotonically with increasing $ε$. The total TBE corrections to the extracted values of $G^{s}_{E}+βG^{s}_{M}$ in recent experiments of HAPPEX and G0 are, depending on kinematics, found to be large and range between 13% to -75% but small in the case of A4 experiments.

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Keitaro Nagata, Hai Qing Zhou, Chung Wen Kao, Shin Nan Yang. 2009-04-29. Contribution of Two-Boson-Exchange with $Δ(1232)$ Excitation to Parity-Violating Elastic Electron-Proton Scattering. https://doi.org/10.1103/physrevc.79.062501

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