Reconstructing generalised parton distributions from the lattice off-forward Compton amplitude
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arXiv
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| Autori principali: | , , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| author | 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. |
| author_facet | 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. |
| contents | 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 $m_π=412\;\text{MeV}$ 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_06256 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Reconstructing generalised parton distributions from the lattice off-forward Compton amplitude 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. High Energy Physics - Lattice High Energy Physics - Phenomenology Nuclear Theory 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 $m_π=412\;\text{MeV}$ 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. |
| title | Reconstructing generalised parton distributions from the lattice off-forward Compton amplitude |
| topic | High Energy Physics - Lattice High Energy Physics - Phenomenology Nuclear Theory |
| url | https://arxiv.org/abs/2405.06256 |