Production of light (anti)nuclei in pp collisions at $$ \sqrt{s} $$ = 13 TeV

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 $$ \sqrt{s} $$ 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.

Production of light (anti)nuclei in pp collisions at $$\sqrt{s} = 5.02$$ TeV

“…It is evident that there is no single parameterisation of the system size that is able to fit both the measured B 2 and B 3 . However, as stated also in [24], charged-particle multiplicity is not a perfect proxy for the system size, because for each multiplicity the source radius depends also on the transverse-momentum of the particle of interest. Anyhow, the data corresponding to the different collision systems and energies confirm a trend with multiplicity, which can be interpreted as an effect of the interplay between the size of the system and that of the nucleus.…”

“…In particular, it is now understood that the increase with transverse momentum of the coalescence parameter in INEL > 0 collisions is, in large part, due to the change in shape of the transverse momentum spectra of protons in different multiplicity intervals [10]. It is also worth mentioning that in pp collisions at high multiplicity (HM) [24], where the system size is larger than the one resulting from INEL > 0 collisions, the raise with p T cannot be neglected even in fine multiplicity classes. In [24], it was shown that the B A as a function of transverse momentum can be described by coalescence predictions, assuming a Gaussian wave function for the nuclei.…”

“…It is also worth mentioning that in pp collisions at high multiplicity (HM) [24], where the system size is larger than the one resulting from INEL > 0 collisions, the raise with p T cannot be neglected even in fine multiplicity classes. In [24], it was shown that the B A as a function of transverse momentum can be described by coalescence predictions, assuming a Gaussian wave function for the nuclei.…”

“…The first important step in the analysis is the particle identification. As already shown in previous works [1,6,10,23,24], the identification of (anti)nuclei is performed with two different methods, depending on the particle species and on the transverse momentum. For (anti)protons and (anti)deuterons with p T < 1 GeV/c, the identification relies on the measurement of the dE/dx using the TPC.…”

Production of light antinuclei in $pp$ collisions by dynamical coalescence and their fluxes in cosmic rays near earth

“…Measurements are usually performed in pA or AA reactions [43][44][45][46][47]. Data in pp collisions are scarce and only available at TeV energies [17,48,49]. We thus do not have the chance to test our model calculation in lower collision energies below TeV.…”