13 Search Results

The first measurement of ³_ΛH and $$^{3}_{\overline{Λ}}$$$$\overline{H}$$ differential production with respect to transverse momentum and centrality in Pb–Pb collisions at √s_NN = 5.02 TeV is presented. The ³_ΛH has been reconstructed via its two-charged-body decay channel, i.e., ³_ΛH → ³He → π^-. A Blast-Wave model fit of the p_T-differential spectra of all nuclear species measured by the ALICE collaboration suggests that the kinetic freeze-out surface is consistent with that of other nuclei. The ratio between the integrated yields of ³_ΛH and ³He is compared to predictions from the statistical hadronisation model and the coalescence model, with the latter being favouredmore » by the presented measurements.« less

The production yields of antideuterons and antiprotons are measured in pp collisions at a center-of-mass energy of $$\sqrt{s}$$ = 13 TeV, as a function of transverse momentum (p_T) and rapidity (y), for the first time rapidity-differentially up to |y| = 0.7. The measured spectra are used to study the p_T and rapidity dependence of the coalescence parameter B₂, which quantifies the coalescence probability of antideuterons. The p_T and rapidity dependence of the obtained B₂ is extrapolated for p_T > 1.7 GeV/c and |y| = 0.7 using the phenomenological antideuteron production model implemented in Pythia 8.3 as well as a baryonmore » coalescence afterburner model based on EPOS 3. Such measurements are of interest to the astrophysics community, since they can be used for the calculation of the flux of antinuclei from cosmic rays, in combination with coalescence models.« less

This Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced $$ρ$$⁰ mesons. The $$ρ$$⁰ mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the cos(2φ) modulation, where φ is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral Pb–Pb collisions at a center-of-mass energy of $$\sqrt{s_{NN}}$$ = 5.02 TeV per nucleon pair. Different impact-parameter regions are selectedmore » by classifying the events in nuclear-breakup classes. The amplitude of the cos(2φ) modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations describe the measured cos(2φ) anisotropy and its impact-parameter dependence as the result of a quantum interference effect at the femtometer scale, arising from the ambiguity regarding which of the nuclei is the photon source in the interaction.« less