Light antinuclei, like antideuteron and antihelium-3, are ideal probes for new, exotic physics because their astrophysical backgrounds are suppressed at low energies. In order to exploit fully the inherent discovery potential of light antinuclei, a reliable description of their production cross sections in cosmic ray interactions is crucial. We provide therefore the cross sections of antideuteron and antihelium-3 production in pp, pHe, Hep, HeHe, pp and pHe collisions at energies relevant for secondary production in the Milky Way, in a tabulated form which is convinient to use. These predictions are based on QGSJET-II-04m and the state of the art coalescence model WiFunC, which evaluates the coalesence probability on an event-by-event basis, including both momentum correlations and the dependence on the emission volume. In addition, we comment on the importance of a Monte Carlo description of the antideuteron production and on the use of event generators in general. In particular, we discuss the effect of two-particle momentum correlations provided by Monte Carlo event generators on antinuclei production.
Light (anti-) nuclei are a powerful tool both in collider physics and astrophysics. In searches for new and exotic physics, the expected small astrophysical backgrounds at low energies make these antinuclei ideal probes for, e.g., dark matter. At the same time, their composite structure and small binding energies imply that they can be used in collider experiments to probe the hadronisation process and two-particle correlations. For the proper interpretation of such experimental studies, an improved theoretical understanding of (anti-) nuclei production in specific kinematic regions and detector setups is needed. In this work, we develop a coalescence framework for (anti-) deuteron production which accounts for both the emission volume and momentum correlations on an event-by-event basis. This framework goes beyond the equal-time approximation, which has been commonly assumed in femtoscopy experiments and (anti-) nucleus production models until now. Using PYTHIA 8 as an event generator, we find that the equal-time approximation leads to an error of O(10%) in low-energy processes like ฮฅ decays, while the errors are negligible at LHC energies. The framework introduced in this work paves the way for tuning event generators to (anti-) nuclei measurements.
The production of light nuclei and antinuclei in particle collisions can be described as the coalescence of final state nucleons that are close in phase space. In heavy ion collisions, it is usually assumed that the formation probability is controlled by the size of the interaction region, while nucleon momentum correlations are either neglected or treated as a collective effect. Interestingly, recent experimental data on nucleus and hadron production in ๐ ๐ collisions at LHC show evidence for such collective behaviour. Here, however, we argue that such data are naturally explained using QCD inspired event generators if both nucleon momentum correlations and the size of the emission volume of nucleons are considered. In order to consider both effects simultaneously, we employ a per-event coalescence model based on the Wigner function representation of the nucleus state. The model predicts the size and ๐ ๐ dependence of the source volume measured at LHC, and it has therefore no free parameters. Finally, we comment on the validity of the underlying assumptions of the femtoscopy framework in small interacting systems and its relation to nuclear coalescence.
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