https://doi.org/10.1140/epjc/s10052-023-12165-8
Regular Article - Theoretical Physics
Probing gluon saturation via diffractive jets in ultra-peripheral nucleus-nucleus collisions
1
Institut de physique théorique, CNRS, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
2
Department of Physics, Columbia University, 10027, New York, NY, USA
3
European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) and Fondazione Bruno Kessler, Strada delle Tabarelle 286, 38123, Villazzano, TN, Italy
4
Key Laboratory of Particle Physics and Particle Irradiation (MOE), Institute of frontier and interdisciplinary science, Shandong University, 266237, Qingdao, Shandong, China
Received:
1
June
2023
Accepted:
20
October
2023
Published online:
25
November
2023
We argue that semi-inclusive photo-production of a pair of hard jets via coherent diffraction in nucleus-nucleus ultra-peripheral collisions at high energy is a golden channel to study gluon saturation. The dominant contribution is the diffractive production of three jets in an asymmetric configuration. Two of the jets are hard and propagate at nearly central pseudo-rapidities. The third jet is semi-hard, with transverse momentum comparable to the nuclear saturation momentum, and is well separated in pseudo-rapidity from the hard dijets. The emission of the semi-hard jet allows for strong scattering, thus avoiding the “higher-twist” suppression of the exclusive dijet production due to colour transparency. We compute the trijet cross-section using the diffractive TMD factorisation which emerges from the CGC effective theory at high energy. The cross-section is controlled by gluon saturation, which leaves its imprints on the structure of the final state, notably on the rapidity distribution.
© The Author(s) 2023
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