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Abstract The interaction of $$\textrm{K}^{-}$$ K - with protons is characterised by the presence of several coupled channels, systems like $${\overline{\textrm{K}}}^0$$ K ¯ 0 n and $$\uppi \Sigma $$ π Σ with a similar mass and the same quantum numbers as the $$\textrm{K}^{-}$$ K - p state. The strengths of these couplings to the $$\textrm{K}^{-}$$ K - p system are of crucial importance for the understanding of the nature of the $$\Lambda (1405)$$ Λ ( 1405 ) resonance and of the attractive $$\textrm{K}^{-}$$ K - p strong interaction. In this article, we present measurements of the $$\textrm{K}^{-}$$ K - p correlation functions in relative momentum space obtained in pp collisions at $$\sqrt{s}~=~13$$ s = 13  Te, in p–Pb collisions at $$\sqrt{s_{\textrm{NN}}}~=~5.02$$ s NN = 5.02  Te, and (semi)peripheral Pb–Pb collisions at $$\sqrt{s_{\textrm{NN}}}~=~5.02$$ s NN = 5.02  Te. The emitting source size, composed of a core radius anchored to the $$\textrm{K}^{+}$$ K + p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the $${\overline{\textrm{K}}}^0$$ K ¯ 0 n and $$\uppi \Sigma $$ π Σ inelastic channels on the measured $$\textrm{K}^{-}$$ K - p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights $$\omega $$ ω , necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured $$\textrm{K}^{-}$$ K - p interaction indicates that, while the $$\uppi \Sigma $$ π Σ – $$\textrm{K}^{-}$$ K - p dynamics is well reproduced by the model, the coupling to the $${\overline{\textrm{K}}}^0$$ K ¯ 0 n channel in the model is currently underestimated. 

Abstract In our Galaxy, light antinuclei composed of antiprotons and antineutrons can be produced through high-energy cosmic-ray collisions with the interstellar medium or could also originate from the annihilation of dark-matter particles that have not yet been discovered. On Earth, the only way to produce and study antinuclei with high precision is to create them at high-energy particle accelerators. Although the properties of elementary antiparticles have been studied in detail, the knowledge of the interaction of light antinuclei with matter is limited. We determine the disappearance probability of $${}^{3}\overline{{{{\rm{He}}}}}$$ 3 He ¯ when it encounters matter particles and annihilates or disintegrates within the ALICE detector at the Large Hadron Collider. We extract the inelastic interaction cross section, which is then used as an input to the calculations of the transparency of our Galaxy to the propagation of $${}^{3}\overline{{{{\rm{He}}}}}$$ 3 He ¯ stemming from dark-matter annihilation and cosmic-ray interactions within the interstellar medium. For a specific dark-matter profile, we estimate a transparency of about 50%, whereas it varies with increasing $${}^{3}\overline{{{{\rm{He}}}}}$$ 3 He ¯ momentum from 25% to 90% for cosmic-ray sources. The results indicate that $${}^{3}\overline{{{{\rm{He}}}}}$$ 3 He ¯ nuclei can travel long distances in the Galaxy, and can be used to study cosmic-ray interactions and dark-matter annihilation. 

Abstract In particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD) 1 . These partons subsequently emit further partons in a process that can be described as a parton shower 2 , which culminates in the formation of detectable hadrons. Studying the pattern of the parton shower is one of the key experimental tools for testing QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass m Q and energy E , within a cone of angular size m Q / E around the emitter 3 . Previously, a direct observation of the dead-cone effect in QCD had not been possible, owing to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible hadrons. We report the direct observation of the QCD dead cone by using new iterative declustering techniques 4,5 to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics. 

Abstract The study of the production of nuclei and antinuclei in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this paper, the production of protons, deuterons and $$^{3}\mathrm {He}$$ 3 He and their charge conjugates at midrapidity is studied as a function of the charged-particle multiplicity in inelastic pp collisions at $$\sqrt{s}=5.02$$ s = 5.02 TeV using the ALICE detector. Within the uncertainties, the yields of nuclei in pp collisions at $$\sqrt{s}=5.02$$ s = 5.02 TeV are compatible with those in pp collisions at different energies and to those in p–Pb collisions when compared at similar multiplicities. The measurements are compared with the expectations of coalescence and Statistical Hadronisation Models. The results suggest a common formation mechanism behind the production of light nuclei in hadronic interactions and confirm that they do not depend on the collision energy but on the number of produced particles.