https://doi.org/10.1140/epja/s10050-021-00469-w
Regular Article - Theoretical Physics
On nuclear coalescence in small interacting systems
1
Institutt for fysikk, NTNU, Trondheim, Norway
2
D.V. Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, Russia
Received:
15
December
2020
Accepted:
17
April
2021
Published online:
18
May
2021
The formation of light nuclei can be described as the coalescence of clusters of nucleons into nuclei. In the case of small interacting systems, such as dark matter and 
annihilations or pp collisions, the coalescence condition is often imposed only in momentum space and hence the size of the interaction region is neglected. On the other hand, in most coalescence models used for heavy ion collisions, the coalescence probability is controlled mainly by the size of the interaction region, while two-nucleon momentum correlations are either neglected or treated as collective flow. Recent experimental data from pp collisions at LHC have been interpreted as evidence for such collective behaviour, even in small interacting systems. We argue that these data are naturally explained in the framework of conventional QCD inspired event generators when both two-nucleon momentum correlations and the size of the hadronic emission volume are taken into account. To include both effects, we employ a per-event coalescence model based on the Wigner function representation of the produced nuclei states. This model reproduces well the source size for baryon emission and the coalescence factor 
measured recently by the ALICE collaboration in pp collisions.
© The Author(s) 2021
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