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Montaña, G.

Publications and source records attributed to Montaña, G..

2025 EIC-France Workshop: Physics Highlights and Perspectives

This document presents a synthesis of the theory contributions and discussions from the 2nd EIC-France Workshop, held at IJCLab (Orsay) on 1-3 December 2025. The workshop brought together members of the French hadron-physics community to review recent theoretical developments relevant to the future Electron-Ion Collider (EIC) and to coordinate national efforts in preparation for its early physics program. The report first summarizes the collider's initial running conditions and luminosity performance, as outlined in the EIC Early Science Matrix. It then provides concise overviews of the theoretical presentations on inclusive, semi-inclusive, exclusive, heavy-flavor, and small-x physics. Based on these discussions, two measurements emerged as especially well suited for early EIC operation and strongly aligned with areas of established French expertise: inclusive diffraction and inclusive quarkonium production. These channels offer clean signatures, robust theoretical interpretability, and direct sensitivity to fundamental QCD phenomena such as gluon saturation, heavy-quark dynamics, and the small-x structure of hadrons and nuclei. In addition, the workshop identified longer-term physics opportunities that will benefit from the full capabilities of the EIC after its ramp-up phase. These include accessing the three-dimensional structure of the pion through the Sullivan process and a broader program of exclusive three-body final states, both of which represent high-impact avenues for exploring hadronic structure and non-perturbative QCD. Together, the elements summarized in this report provide a coherent overview of the strategic priorities and scientific ambitions shaping the French community's contribution to the EIC physics program.

FOS: Physical sciences↗

Reggeization of the Pion Exchange in Pion Photoproduction

At high energies, the production of light mesons induced by a photon beam interacting with a nucleon target is governed by the exchange of Regge trajectories in the t-channel. In charge-exchange reactions at small momentum transfer, unnatural parity exchanges, such as pion exchange, dominate. The point-like nature of the photon–pion interaction makes the pion photoproduction reaction an excellent way to study the pion exchange mechanism. However, the nucleon Born terms are required to ensure that the scattering amplitude is gauge invariant. The gauge invariance of the pion exchange amplitude is crucial in approaching its reggeization properly. Here we discuss a novel strategy to reggeize the pion pole which considers explicitly the exchange in the t-channel of all the mesons in the pion trajectory. Each of these exchanges contributes with a pole in spin, known as a Regge pole, and we perform their summation analytically.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗