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arXiv · 2404.03875

Photo-production of $\eta_{c,b}$ near Threshold

Wei-Yang Liu·Ismail Zahed
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Abstract

We analyze the photo-production of $\eta_{c,b}$ off a proton in the threshold region, in terms of C-odd gluonic correlations in the off-forward proton matrix element. Near threshold, the skewness is large leading to a production amplitude that is dominated by four C-odd twist-3 gluon GPDs. We use the QCD instanton vacuum to estimate these C-odd contributions in the proton. The results are used to estimate the differential cross sections for coherent photo-production of $\eta_{c,b}$ in the threshold region, at current electron facilities.

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Wei-Yang Liu, Ismail Zahed. 2024-04-05. Photo-production of $\eta_{c,b}$ near Threshold. https://doi.org/10.1103/physrevd.110.054025

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