Di- production and generalized distribution amplitudes at future electron-ion colliders

Bing’ang Guo; Jing Han; Ya-Ping Xie; Xurong Chen

doi:10.1140/epjc/s10052-025-14227-5

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2025) 85: 506
https://doi.org/10.1140/epjc/s10052-025-14227-5

Regular Article - Theoretical Physics

Di- $π^{0}$ $\pi ^0$ production and generalized distribution amplitudes at future electron-ion colliders

Bing’ang Guo¹^,2^a, Jing Han³, Ya-Ping Xie¹^,4 and Xurong Chen¹^,2^,5

¹ Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
² School of Nuclear Science and Technology, University of Chinese Academy of Sciences, 100049, Beijing, China
³ School of Physics, Zhengzhou University, 450001, Zhengzhou, Henan, China
⁴ University of Chinese Academy of Sciences, 100049, Beijing, China
⁵ Southern Center for Nuclear Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences, 516000, Huizhou, Guangdong, China

^a guobingang@impcas.ac.cn

Received: 13 January 2025
Accepted: 24 April 2025
Published online: 8 May 2025

Abstract

Generalized distribution amplitudes (GDAs) offer valuable insights into the three-dimensional structure of hadrons, delineating the amplitudes associated with the transition from a quark–antiquark pair to a hadron pair. Currently, hadron GDAs can be probed in electron–positron collisions, with experimental feasibility demonstrated at facilities such as Belle and BESIII. In this study, we put forth the proposition that hadron GDAs can also be investigated in electron–hadron collisions at forthcoming Electron-Ion Colliders (EICs), specifically through the subprocess $γ^{*} γ \to h_{1} h_{2} .$ $\gamma ^*\gamma \rightarrow h_1 h_2.$ In this framework, a quasi-real photon, emitted by the ion, exhibits a photon flux proportional to the square of the ion’s electric charge. Consequently, we anticipate that the cross sections in EICs will be substantially larger than those in electron–positron collisions. We present numerical calculations pertaining to di- $π^{0}$ $\pi ^0$ production employing the equivalent photon approximation (EPA). Our findings suggest that, within the same kinematic region, electron-proton (e-p) collisions at the EIC could yield an event rate comparable to that of Belle II, while electron-gold (e-Au) collisions are expected to generate an even greater number of events. This enhanced event rate facilitates a high-precision examination of di- $π^{0}$ $\pi ^0$ GDAs at the EIC.

© The Author(s) 2025

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