Double DVCS amplitudes including kinematic twist-3 and 4 corrections - CNRS - Centre national de la recherche scientifique
Proceedings/Recueil Des Communications Proceedings of Science Année : 2025

Double DVCS amplitudes including kinematic twist-3 and 4 corrections

Résumé

Generalized parton distributions (GPDs) are off-forward matrix elements of quark and gluon operators that work as a window to the total angular momentum of partons and their transverse imaging (nucleon tomography). To access GPDs one needs to look into exclusive processes which are usually studied in a kinematic regime known as the Bj\"orken limit. In this limit, the photon virtualities are much larger than the hadron mass $M$, and the kick to the hadron measured by the Mandelstam's variable $t$. It turns out that this is not enough for the purposes of a precise GPD extraction and, in particular, of nucleon tomography for which measurements in a sizable range of $t$ are required. Deviation with respect to the Bj\"orken limit induces kinematic higher-twist corrections which enter the amplitudes with powers of $|t|/\mathbb{Q}^2$ and $M^2/\mathbb{Q}^2$, where $\mathbb{Q}^2$ denotes the scale of the process (basically, the sum of photon virtualities in the case of DDVCS). There are also corrections by the name of "genuine" higher twists which are a separate topic and are not the subject of this research study. In this manuscript, we present novel calculations of DDVCS amplitudes off a (pseudo-)scalar target including up to kinematic twist-4 corrections. These results are important for measuring DDVCS, DVCS and TCS through the Sullivan process and off helium-4 target at the future Electron-Ion Collider (EIC) and JLab experiments. Preliminary numerical estimates for the pion target are provided.

Dates et versions

hal-04629684 , version 1 (30-06-2024)

Identifiants

Citer

V. Martinez-Fernandez, B. Pire, P. Sznajder, J. Wagner. Double DVCS amplitudes including kinematic twist-3 and 4 corrections. 31st International Workshop on Deep Inelastic Scattering (DIS2024) 8–12 April 2024 Grenoble, France, Proceedings of Science, PoS(DIS2024) (PoS(DIS2024)), pp.205, 2025, ⟨10.22323/1.469.0205⟩. ⟨hal-04629684⟩

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