Reconstructing generalised parton distributions from the lattice off-forward Compton amplitude
| Autor: | Hannaford-Gunn, A., Can, K. U., Crawford, J. A., Horsley, R., Rakow, P. E. L., Schierholz, G., Stüben, H., Young, R. D., Zanotti, J. M. |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | We present a determination of the structure functions of the off-forward Compton amplitude $\mathcal{H}_1$ and $\mathcal{E}_1$ from the Feynman-Hellmann method in lattice QCD. At leading twist, these structure functions give access to the generalised parton distributions (GPDs) $H$ and $E$, respectively. This calculation is performed for an unphysical pion mass of $m_{\pi}=412\;\text{MeV}$ and four values of the soft momentum transfer, $t\approx 0, -0.3, -0.6, -1.1\;\text{GeV}^2$, all at a hard momentum scale of $\bar{Q}^2\approx 5\;\text{GeV}^2$. Using these results, we test various methods to determine properties of the real-time scattering amplitudes and GPDs: (1) we fit their Mellin moments, and (2) we use a simple GPD ansatz to reconstruct the entire distribution. Our final results show promising agreement with phenomenology and other lattice results, and highlight specific systematics in need of control. Comment: 20 pages, 14 figures. Minor updates to text. Version to appear in Phys. Rev. D |
| Databáze: | arXiv |
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