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arXiv · 2506.18905

Relativistic corrections to exclusive photoproduction of Quarkonia near-threshold

Sarah K. Blask·Sean Fleming·Thomas Mehen·Jyotirmoy Roy·Iain W. Stewart·Fanyi Zhao
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Abstract

Non-relativistic QCD (NRQCD) is used to calculate the relativistic correction to the amplitude for exclusive photoproduction of vector Quarkonia in the near-threshold region within the generalized parton distribution (GPD) framework. The relativistic corrections are found to be large for $J/\psi$, and lead to a breakdown of the GPD moment expansion near threshold. Cross-sections for both $J/\psi$ and $\Upsilon$ are calculated with the former being compared to the data. We also demonstrate the presence of endpoint divergences for the relativistic correction away from the near-threshold regime.

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Sarah K. Blask, Sean Fleming, Thomas Mehen, Jyotirmoy Roy, Iain W. Stewart, Fanyi Zhao. 2025-06-23. Relativistic corrections to exclusive photoproduction of Quarkonia near-threshold. https://arxiv.org/abs/2506.18905

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