Abstract
Understanding the production mechanism of light (anti)nuclei is one of the key challenges of nuclear physics and has important consequences for astrophysics, since it provides an input for indirect dark-matter searches in space. In this paper, the latest results about the production of light (anti)nuclei in pp collisions at sqrt{s} = 13 TeV are presented, focusing on the comparison with the predictions of coalescence and thermal models. For the first time, the coalescence parameters B2 for deuterons and B3 for helions are compared with parameter-free theoretical predictions that are directly constrained by the femtoscopic measurement of the source radius in the same event class. A fair description of the data with a Gaussian wave function is observed for both deuteron and helion, supporting the coalescence mechanism for the production of light (anti)nuclei in pp collisions. This method paves the way for future investigations of the internal structure of more complex nuclear clusters, including the hypertriton.
Highlights
Understanding the production mechanism of lightnuclei is one of the key challenges of nuclear physics and has important consequences for astrophysics, since it provides an input for indirect dark-matter searches in space
The results presented in this paper are obtained from data collected in 2016, 2017 and 2018, both with minimum bias (MB) and high multiplicity (HM) triggers
The multiplicity classes used for this measurement are reported in Tab 2, together with the corresponding pT-integrated yields. (Anti)protons,deuterons andhelions are fitted with a Lévy-Tsallis function [52], which is used to extrapolate the yields in the unmeasured pT region
Summary
A detailed description of the ALICE apparatus and its performance can be found in refs. [38] and [39]. The multiplicity classes are determined from the sum of the signal amplitudes measured by the V0 detectors and defined in terms of the percentiles of the INEL > 0 pp cross section, where an INEL > 0 event is a collision with at least a charged particle in the pseudorapidity region |η|< 1 [45]. For this purpose, charged particles are measured with SPD tracklets, obtained from a pair of hits in the first and second layer of the SPD, respectively. A detailed description of the dNch/dη estimation can be found in ref. [46]
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