Corrections to the Forward Limit Dispersion Relations for γZ-Exchange Contributions

2023/06/28 by Qianqian Guo, Guo, Qian-Qian, Haiqing Zhou +1
Mathematics · #Advanced Mathematical Physics Problems #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th)

paper · pdf · doi:10.48550/arxiv.2306.16294

openalex publication_date 2023/06/28 · openalex created_date 2023/06/30 · openalex updated_date 2026/07/28

Abstract

The weak charge of the proton Q_\textrmw is one of the most fundamental quantities in physics. It can be determined by measuring the parity asymmetry A_\textrmPV in elastic ep scattering, where the γZ-exchange contributions are crucial. For the past fifteen years, dispersion relations (DRs) in the forward limit have been widely used as a model-independent method to estimate these contributions. In this work, we study corrections to these forward-limit DRs. We first estimate these corrections using pointlike interactions as an illustrative example. We then estimate the γZ-exchange contributions for the upcoming P2 experiment through both direct calculation and the forward-limit DRs, within the framework of low-energy effective interactions. The results indicate that the correction to the forward-limit DR for \Box_γZ^V is around 47% for the upcoming P2 experiment, which will significantly modify the extracted value of Q_\textrmw.

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