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arXiv · 1102.5334

New formulation of gamma-Z box corrections to the weak charge of the proton

P. G. Blunden·W. Melnitchouk·A. W. Thomas
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Abstract

We present a new formulation of one of the major radiative corrections to the weak charge of the proton -- that arising from the axial-vector hadron part of the $γZ$ box diagram, $\Re{\rm e}\, \Box_{γZ}^{\rm A}$. This formulation, based on dispersion relations, relates the $γZ$ contributions to moments of the $F_3^{γZ}$ interference structure function. It has a clear connection to the pioneering work of Marciano and Sirlin, and enables a systematic approach to improved numerical precision. Using currently available data, the total correction from all intermediate states is $\Re{\rm e}\, \Box_{γZ}^{\rm A} = 0.0044(4)$ at zero energy, which shifts the theoretical estimate of the proton weak charge from $0.0713(8)$ to $0.0705(8)$. The energy dependence of this result, which is vital for interpreting the Q$_{\rm weak}$ experiment, is also determined.

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P. G. Blunden, W. Melnitchouk, A. W. Thomas. 2011-07-21. New formulation of gamma-Z box corrections to the weak charge of the proton. https://doi.org/10.1103/physrevlett.107.081801

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