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

Fuente: arXiv
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Main Authors: Guo, Qian-Qian, Zhou, Hai-Qing
Format: Preprint
Published: 2023
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author Guo, Qian-Qian
Zhou, Hai-Qing
author_facet Guo, Qian-Qian
Zhou, Hai-Qing
contents The weak charge of the proton $Q_{\textrm{w}}$ is one of the most fundamental quantities in physics. It can be determined by measuring the parity asymmetry $A_{\textrm{PV}}$ 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 $Q_{\textrm{w}}$.
format Preprint
id arxiv_https___arxiv_org_abs_2306_16294
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Corrections to the Forward Limit Dispersion Relations for $γZ$-Exchange Contributions
Guo, Qian-Qian
Zhou, Hai-Qing
High Energy Physics - Phenomenology
Nuclear Experiment
Nuclear Theory
The weak charge of the proton $Q_{\textrm{w}}$ is one of the most fundamental quantities in physics. It can be determined by measuring the parity asymmetry $A_{\textrm{PV}}$ 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 $Q_{\textrm{w}}$.
title Corrections to the Forward Limit Dispersion Relations for $γZ$-Exchange Contributions
topic High Energy Physics - Phenomenology
Nuclear Experiment
Nuclear Theory
url https://arxiv.org/abs/2306.16294