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| Main Authors: | , , , |
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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2603.09831 |
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| _version_ | 1866911503388508160 |
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| author | Danilkin, I. Pasquini, B. Ronchi, M. Vanderhaeghen, M. |
| author_facet | Danilkin, I. Pasquini, B. Ronchi, M. Vanderhaeghen, M. |
| contents | We present a once-subtracted dispersion relation (DR) formalism for the virtual Compton scattering (VCS) process from threshold up to the $Δ(1232)$ energy region. The formalism aims at extracting the nucleon's electric and magnetic generalized polarizabilities from the $e^- p \to e^- γp$ process, in view of the precision goals of the present and near future experiments at Jefferson Lab. The present work improves upon the existing unsubtracted DR formalism in several ways. The required $s$- and $t$-channel discontinuities in the subtracted dispersion integrals are obtained in a largely data-driven manner in this energy region. The $s$-channel dispersive integrals are reconstructed from $γ^\ast p \to πN \to γp$ using pion photo- and electro-production data, while the $t$-channel dispersion integrals are evaluated from $γ^\ast γ\to ππ\to N \bar N$ using recent dispersive analyses of both the $γ^\ast γ\to ππ$ and $ππ\to N \bar N$ processes. We compare our results to VCS data and show the sensitivity of the observables to the nucleon's scalar generalized polarizabilities, which enter the present formalism as subtraction constants. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_09831 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Subtracted Dispersion Relations for Virtual Compton Scattering off the Proton Danilkin, I. Pasquini, B. Ronchi, M. Vanderhaeghen, M. High Energy Physics - Phenomenology We present a once-subtracted dispersion relation (DR) formalism for the virtual Compton scattering (VCS) process from threshold up to the $Δ(1232)$ energy region. The formalism aims at extracting the nucleon's electric and magnetic generalized polarizabilities from the $e^- p \to e^- γp$ process, in view of the precision goals of the present and near future experiments at Jefferson Lab. The present work improves upon the existing unsubtracted DR formalism in several ways. The required $s$- and $t$-channel discontinuities in the subtracted dispersion integrals are obtained in a largely data-driven manner in this energy region. The $s$-channel dispersive integrals are reconstructed from $γ^\ast p \to πN \to γp$ using pion photo- and electro-production data, while the $t$-channel dispersion integrals are evaluated from $γ^\ast γ\to ππ\to N \bar N$ using recent dispersive analyses of both the $γ^\ast γ\to ππ$ and $ππ\to N \bar N$ processes. We compare our results to VCS data and show the sensitivity of the observables to the nucleon's scalar generalized polarizabilities, which enter the present formalism as subtraction constants. |
| title | Subtracted Dispersion Relations for Virtual Compton Scattering off the Proton |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2603.09831 |