Near-Threshold J/$ψ\to μ^+μ^-$ Photoproduction and the Gluonic Gravitational Form Factors of the Proton

007 Collaboration; S. Joosten; Z. -E. Meziani; S. Prasad; J. Swartz; B. Duran; M. K. Jones; H. Klest; M. Paolone; C. Peng; W. Armstrong; H. Atac; E. Chudakov; H. Bhatt; D. Bhetuwal; M. Boer; A. Camsonne; J. -P. Chen; M. Dalton; N. Deokar; M. Diefenthaler; J. Dunne; L. El Fassi; F. Flor; E. Fuchey; H. Gao; D. Gaskell; O. Hansen; F. Hauenstein; D. Higinbotham; S. Jia; A. Karki; C. Keppel; P. King; H. S. Ko; X. Li; R. Li; D. Mack; S. Malace; M. McCaughan; R. E. McClellan; R. Michaels; D. Meekins; L. Pentchev; E. Pooser; A. Puckett; R. Radloff; M. Rehfuss; P. E. Reimer; S. Riordan; B. Sawatzky; A. Smith; N. Sparveris; H. Szumila-Vance; S. Wood; J. Xie; Z. Ye; C. Yero; Z. Zhao

arXiv · 2602.14416

Near-Threshold J/$ψ\to μ^+μ^-$ Photoproduction and the Gluonic Gravitational Form Factors of the Proton

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Abstract

We report on the measurement of the two-dimensional differential cross section for near-threshold J/$ψ\to μ^+μ^-$ photoproduction from the J/$ψ$-007 experiment in Hall C at Jefferson Lab. Our results agree with the previously published J/$ψ\to e^+e^-$ results. We extract the integrated photoproduction cross section and find no evidence for open-charm contributions. A combined analysis of both decay channels following a Holographic QCD approach yields improved experimental constraints on the gluonic gravitational form factor $\mathcal{C}_g(t)$. Our results agree with recent lattice QCD calculations and we obtain $\mathcal{C}_g(t)$ with a comparable statistical precision to lattice QCD. Our results support a spatial picture where gluons dominate at larger radii with a confining inward pressure. This work provides new input for exploring the mechanical properties of gluons inside the proton.

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007 Collaboration, S. Joosten, Z. -E. Meziani, S. Prasad, J. Swartz, B. Duran, M. K. Jones, H. Klest, M. Paolone, C. Peng, W. Armstrong, H. Atac, E. Chudakov, H. Bhatt, D. Bhetuwal, M. Boer, A. Camsonne, J. -P. Chen, M. Dalton, N. Deokar, M. Diefenthaler, J. Dunne, L. El Fassi, F. Flor, E. Fuchey, H. Gao, D. Gaskell, O. Hansen, F. Hauenstein, D. Higinbotham, S. Jia, A. Karki, C. Keppel, P. King, H. S. Ko, X. Li, R. Li, D. Mack, S. Malace, M. McCaughan, R. E. McClellan, R. Michaels, D. Meekins, L. Pentchev, E. Pooser, A. Puckett, R. Radloff, M. Rehfuss, P. E. Reimer, S. Riordan, B. Sawatzky, A. Smith, N. Sparveris, H. Szumila-Vance, S. Wood, J. Xie, Z. Ye, C. Yero, Z. Zhao. 2026-02-24. Near-Threshold J/$ψ\to μ^+μ^-$ Photoproduction and the Gluonic Gravitational Form Factors of the Proton. https://arxiv.org/abs/2602.14416

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