{"@context":"http://schema.org","@id":"https://doi.org/10.17182/hepdata.158317.v1","@reverse":{"isBasedOn":[{"@type":"ScholarlyArticle","identifier":{"@type":"PropertyValue","propertyID":"URL","value":"https://inspirehep.net/literature/2842103"}}]},"@type":"Dataset","additionalType":"Collection","author":{"@type":"Organization","name":"ALICE Collaboration"},"creator":{"@type":"Organization","name":"ALICE Collaboration"},"datePublished":"2025","description":"In this Letter, the first evidence of the ${}^4_{\\bar{\\Lambda}}\\overline{\\mathrm{He}}$ antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number $A=4$, specifically (anti)${}^4_{\\Lambda}\\mathrm{H}$ and (anti)${}^4_{\\Lambda}\\mathrm{He}$. In addition, the antiparticle-to-particle ratios for both hypernuclei (${}^4_{\\bar{\\Lambda}}\\overline{\\mathrm{H}}$ / ${}^4_{\\Lambda}\\mathrm{H}$ and ${}^4_{\\bar{\\Lambda}}\\overline{\\mathrm{He}}$ / ${}^4_{\\Lambda}\\mathrm{He}$) are shown, which are sensitive to the baryochemical potential of the strongly-interacting matter created in heavy-ion collisions. The results are obtained from a data sample of central Pb--Pb collisions, collected during the 2018 LHC data-taking at a center-of-mass energy per nucleon pair of $\\sqrt{s_{\\mathrm{NN}}} = $ 5.02 TeV. The yields measured for the average of the charge-conjugated states  are found to be $[0.78 \\; \\pm \\; 0.19  \\; \\mathrm{(stat.)} \\; \\pm \\; 0.17 \\; \\mathrm{(syst.)}]  \\times 10^{-6}$ for the (anti)${}^4_{\\Lambda}\\mathrm{H}$ and $[1.08 \\; \\pm \\; 0.34  \\; \\mathrm{(stat.)} \\; \\pm \\; 0.20  \\; \\mathrm{(syst.)}]  \\times 10^{-6}$ for the (anti)${}^4_{\\Lambda}\\mathrm{He}$, and the measured antiparticle-to-particle ratios are in agreement with unity. The presence of (anti)${}^4_{\\Lambda}\\mathrm{H}$ and (anti)${}^4_{\\Lambda}\\mathrm{He}$ excited states is expected to strongly enhance the production yield of these hypernuclei. The yield values exhibit a combined deviation of 3.3$\\sigma$ from the theoretical ground-state-only expectation, while the inclusion of the excited states in the calculations leads to an agreement within 0.6$\\sigma$ with the present measurements. Additionally, the measured (anti)${}^4_{\\Lambda}\\mathrm{H}$ and (anti)${}^4_{\\Lambda}\\mathrm{He}$ masses are compatible with the world-average values within the uncertainties.","hasPart":[{"@id":"https://doi.org/10.17182/hepdata.158317.v1/t1","@type":"Dataset","description":"average pT-integrated yield of particle and antiparticle of both analyzed (anti)hypernuclei in Pb-Pb collisions in 0-10% V0M centrality class","name":"Corrected measured yield"},{"@id":"https://doi.org/10.17182/hepdata.158317.v1/t2","@type":"Dataset","description":"mass measurement of both analyzed (anti)hypernuclei in Pb-Pb collisions in 0-10% V0M centrality class","name":"Measured masses"},{"@id":"https://doi.org/10.17182/hepdata.158317.v1/t3","@type":"Dataset","description":"antiparticle-to-particle ratio of the analyzed (anti)hypernuclei in Pb-Pb collisions in 0-10% V0M centrality class","name":"Antiparticle-to-particle ratio"}],"identifier":[{"@type":"PropertyValue","propertyID":"HEPDataRecord","value":"https://www.hepdata.net/record/ins2842103?version=1"},{"@type":"PropertyValue","propertyID":"HEPDataRecordAlt","value":"https://www.hepdata.net/record/158317"}],"inLanguage":"en","name":"First measurement of A = 4 (anti)hypernuclei at the LHC","provider":{"@type":"Organization","name":"HEPData"},"publisher":{"@type":"Organization","name":"HEPData"},"url":"https://www.hepdata.net/record/ins2842103?version=1","version":1}